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General control line discussion => Open Forum => Topic started by: Bob Hunt on May 01, 2018, 06:47:24 AM
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It is time to revisit the discussion about the rule governing the weighing of CL Stunt models as it now exists in the AMA rule book, I fully realize that this may soon - or eventually - get booted over to the rules discussion forum here. But, I wanted to let everyone know how I feel about the current rules and give them a chance to voice their opinions here on the main forum. Not everyone visits the rules forum here because not everyone is interested in competition. The rules regarding weighing models affects everyone here in some manner, so everyone here should be aware of what’s going on.
As the rules read now, a CL Stunt model with a glow engine gets weighed without the fuel on board, while an electric powered model must be weighed with the battery on board. There is a terrible inequity here, and a huge safety issue. Glow models can add as much as 7 to 8 ounces of fuel after the weigh in process and their takeoff weight goes up that much because a fluid ounce of fuel weighs nominally an ounce. So, a glow model that weighs in at 64 ounces gets to legally fly on thinner lines than an electric model that weighs in at 65 ounces (the line size break is 64 ounces…), even though it may weigh as much as 72 ounces or more at takeoff! This is just wrong, it's unsafe, and it needs to be changed.
If the rule regarding airplane weight versus line diameter is meant for safety, how is it safer to allow a glow model to become airborne at a higher weight than an electric model, while also allowing it to fly on thinner lines?
This is not a new discussion, but it is one that needs to be resolved for the sake of safety and fairness. I intend to bring this up with the CLACB as a potential emergency rule change item. There is no valid argument that I can see to allow a glow model to exceed the weight limits for a given line size at takeoff. Sure, the fuel burns off, and hence the weight burns off, but at takeoff many glow models are exceeding the 64 ounce line size break point; sometimes by a lot!
The rub is how do we then enforce this rule. Will we have to ask the flier to present his or her model for weigh-in with a full tank of fuel? Will we work on an honor basis and allow the flier to just tell the weigh in person how big the tank is and then the weight of the fuel can be calculated and added? I’m certain that some of you will come up with brilliant ideas to answer this question. I’m equally certain that there will be many who will vehemently oppose what I am proposing. My question to them would be, “Are you opposed to this because my math or my reasoning about safety an fairness isn’t correct, or are you just trying to keep your competition advantage?”
Thanks - Bob Hunt
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All great points Bob.
My belief is that any lessening of weight requirements will not "fly" with the Academy. The powers that be there perceive that reducing pull tests will result in safety issues......
You "honor system" of tank size sounds good, but may be easily circumvented by someone on the margin of being able to use smaller lines.
I would wager that planes around the weight break for line size (64 ounces. I believe) consume more than 4 ounces of fuel. The next line size break is 90 ounces, I believe.
Rather than argue the economy of a belchfire .79, adding 4 four ounces to the weight of IC contenders might do the trick?
Whatever is done (if anything), I hope that there can be full agreement prior to involving the AMA, as I feel that they would only compound the problem (if there is one).
Good thoughts!
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Hi Rich:
Nowhere in my missive did I propose any lessening of weight requirements. I only proposed that all models in the Stunt event be weighed at takeoff weight. And, I've already discussed this at length with Tony Stillman at AMA. He is in total agreement that the models should all be weighed at takeoff weight. He suggested that I first go through proper chain of command channels and propose this as an emergency rule change proposal to the CLACB (Control Line Aerobatics Contest Board). He said if that fails to yield fruit, then I should make the emergency rule change proposal to the AMA Safety Committee and he would back me up.
Thanks for your thoughts. - Bob
If all you are going to do is raise the weight for IC engines, I don't see why it is necessary or what it accomplishes, either for safety or for competitive balance. It's not like people are building their bellcrank mounts to make, say, a 41-lb pull test but not a 44-lb pull test (just using my own airplane as an example). And, for the most part, most pull test devices are probably not accurate to better than about 5 lb.
As far as line sizes go, you get no advantage to using .015 vs .018 if you are anywhere close to the break point; you are driven to use .018s for precision reasons alone. I won the NATs using what would now be considered "oversize" lines, that is, .018 on a 62 ounce airplane.
In any case, this certainly doesn't meet the criteria for an emergency rule change. This is more-or-less the same situation we have had for 50-60 years, since pull tests were required, and the current line size and break points were designed based on the current situation, and no one thinks the current situation is in any way unsafe or even marginal. In fact, it has a huge margin, roughly 4x, which hardly changes if you add 6 ounces to everyone's airplane (again, this if FAR inside the usual tolerances of weighing and testing).
And how far are you going to take this? Fill the tank and dribble fuel everywhere? Just take someone's word for it? What if someone says they run 6.5 ounces, and it's really 7.2? Is that really going to make a difference where people are weighing airplanes with fish scales to +-4 ounces, or having their postal scale change by 10% due to temperature effects on a load cell?
The only thing I see this accomplishing is to slightly annoy IC fliers with an irrelevant pull test change, mostly to make electric fliers to feel better about the ridiculous "weigh-in pissing contest" that a few engage in, based on the premise that how heavy your airplane is somehow says something about one's skills as a builder (which is doesn't), or try to impress others with the half an ounce you saved so you improved performance (which means nothing).
I really don't care about this change, add 4 lb to my pull test, what difference does it make? I strongly suggest this stems from pissing contest aspect, and some electric fliers are embarrassed about reporting 73 ounces while IC fliers report 64, because there are still some nitwits who think their airplane weight is some sort of measure of their building skills. It's not changing the competition any and no one is going to build their airplanes any differently. It makes no difference at all for safety, since this is far inside the existing tolerances and far inside the existing margins
No one (or only a few people) will end up on different size lines, and those who are forced from .015 to .018 will almost certainly be better off for it, even if they don't know it now.
Brett
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I agree with what Brett said here! Also the Term "line break point", seems very arbitrary to me since there is actually some safety margin included in that number!
I currently have a IC airplane that weighs 63 ounces on my electronic scale at home, 63 ounces on a scale at the post office and 63 ounces on a scale at my butchers shop. When I take it to a contest both here and in CA and they weigh it on one of their funky fish scale it always seems to weigh 64 to 65 ounces.
While it's really not problematic for me because I would fly it on .018 lines anyway for the difference in line stretch it does show the silliness in being so worried about a couple of ounces of weight at a supposed "line break point".
If we are really so worried about this issue we should demand the use of certified scales for weighing!
<= <= <= <= HB~> HB~>
Randy Cuberly
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I'm showing up with an Evo .60 powered 63 ounce plane and a 4 ounce Du-Bro plastic tank. What kind of static can I expect?
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Hi Brett:
You and I don't often disagree these days, and I'm certainly not trying to "pick a fight." Your thoughts are good ones, but consider the legal ramifications of the current AMA rules in respect to weight of models. Should a glow engine model that weighs in at, say, 63 ounces without fuel on board then have fuel added to exceed the weight limits for .012 solids or .015 cables, and then have an accident just after takeoff... Well, if a lawyer got hold of this there could be serious repercussions.
I am not sure how you get that, since the pull test was defined (since I helped defined it) based on the empty weight of an IC airplane and has effectively been in use for something over half a century. And in any case, the difference in weight is in the noise of the measurement errors. I did an eyeball tolerance stackup analysis and it's on the order of 5 lbs or so when you get to the test. That includes the likely bias and scale factor errors in the weighing scale, the bias and scale factor errors of the range of pull test devices, and a guess at the tolerance on the line strength. With everything right down the middle of the error bars, there is roughly a 4x safety factor. It goes down to about 3x when you consider all the errors. That's the difference between a 30 and a 40 lb pull test. The only way to improve that is to start specifying the required performance of the scale and the pull test device. Even without improving the system, you have a 1.5x factor of safety even after a line break and you are flying on one line. That is a typical aerospace specification for structural margin in weight-critical systems. None of this was an accident.
I also don't agree with you about the performance difference between .015 cables and .018 cables. I once said that if I were compelled to have to fly on .018 cables that I would just opt to not fly at all. That's how much of an advantage I feel there is with the thinner lines. Personal preference I guess. I never flew with an abundance of line tension; just enough to do the job. I guess if I had set up my planes to pull harder then I might see the problems you have described. But, this rule proposal is not about that... It's about safety and insuring that we don't have legal action taken against us due to a model flying on the thinner lines in an overweight condition.
Since you didn't quote the analysis or the margins you used in your analysis, I can't assess what you assessed. It's not a legal problem, or if it is, it's the same legal problem we have had for more than half a century. If anything, weighing the electric models with the 10x the battery weight included reduces the legal exposure.
Tony Stillman at AMA agrees with me on this point...
Tony Stillman was not involved when the current 10G and line size break points were established, and I am not sure what his background in aerospace engineering of life-critical systems might be. So, aside from the fact that you went to him before mentioning this supposed problem to the rest of us and getting in your shot first, I am not sure how that affects the engineering issue involved.
The point about .015 vs .018 performance is a reasonable one (although I think you are wrong), but your change doesn't change it for electric, only for IC, which seems to reveal the real motivation - to "even up the playing field" for electric. OK, swell, but as far as I can tell, almost everyone that is potentially affected is *already using .018 lines*, so it changes absolutely nothing in regard.
If someone competitive wants to fly their PA75 airplane on .015 lines, I will happily supply them for free and even hook them up for them, free of charge. Hey, Derek, buddy, do I have a deal for you...
Hey, old buddy, let's not let this become anything more than it is. I highly respect you and your thoughts. All I ask is the same.
No problem here, I am willing to be entirely frank with you because you *do* listen and respond, and generally know what you are talking about. But I don't think this change has anything to do with "safety" or legal exposure, because it has no consequential effect on either. I think it has to do with the feeling of it being "unfair" to have to pull electric 4 lb more than IC, and whatever that stems from.
I don't significantly object to this almost entirely irrelevant change (it changes the pull test by about 4 lbs for IC models) but I do somewhat object to the characterization as a "safety" issue because a lot of actual work and electrons were expended coming up with the current chart based on full-scale aerospace standards, and a consideration of all the factors, and I object strenuously to characterize it as a legal problem. Show your work, let's see the numbers and see the tolerance stackup analysis.
And anticipating the next argument, no, it is not a good idea to "always improve safety" because the best way to improve safety is to shut down the event. You trade off safety margins for performance, and some trades are not sensible. It would be safer, for instance, to require 1/32" 19-strand wire rope, and a 40G pull test. You would have a 8x margin instead of 2x, every single current airplane would be destroyed attempting the 160 lb pull test (although my bellcrank handled 205 for a while) but I am pretty sure you won't have a lot of line-break-induced flyways, think how safe we will all be.
Brett
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Again, I agree with Brett.
I do however agree that from a fairness point of view it does seem unfair to have a different standard of takeoff weight for electrics and IC aircraft.
I would propose that the rules change to include the weight of the fuel at take off based on the quantity of fuel permitted by the onboard tank.
I have never thought it was fair to base pull tests on different "takeoff weights" between Electrics and IC aircraft.
The pull generated is based on their respective flight weights not their fuel types!
I definitely do not think there is anything to be gained by potentially creating problems over perceived "safety issues" which probably do not exist based on past history of our event!
Rather than just increasing the pull test requirement for IC aircraft perhaps a different formulation should be explored for both IC and Electric to determine a common requirement. If a lower requirement is adequate for IC aircraft it is likely also adequate for Electric aircraft based on past experience with IC aircraft.
Randy Cuberly
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I doubt there is any concern about how we pull IC airplanes but in order to have more parity perhaps the electrics could use a sort of K factor- and I’ve done no math- but something like .9 X what the IC would pull. Just an idea.
Dave
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Bob, what were you using on the Saturns, were those lines solids or stranded?
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Take this for what it's worth from a mid pack advanced flyer. I'm new to the full size stunters this year and I've been flying an ARF electric on .018" that's 69 ounces. It pulls pretty good and just seat of the pants experience of 57 years of flying I wouldn't want to fly this thing on .015". Now think of a PA 75 or other big glow engine on a run away flight at 69oz and I can see the danger.
Motorman 8)
Hi Motorman,
I too am a middle (lower) of the pack advanced flyer. My (best) stunter weighs 64 oz's with a VF 46 on a pipe and I feel the .018's are best for me. But that's just me. Someone else might argue that I could fly on .015....... Not me!
Brett & Bobby, I think you guys are having too much fun with this non problem! LL~ LL~ LL~
See you in Woodland Brett, Jerry
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Where was the line of people with IC planes flying away on broken lines and wanting to weight them with fuel onboard before E-Power came along? Oh, there weren't any, and there still aren't. Line maint is still the key, and pull tests aren't max, which will do more long term damage than good, they are only enough to weed out line's about to fail.
Let's not re-write history folks. I "think" part of the issue was at the inception of E-Power, that most of the viable batteries available for stunt weighed over 1Lb (even Brodak shipped the original Electric Clown with a gigantic 3200 or 3600 battery that was big enough to haul a Strega nowadays) As battery weights come down, this is becoming more and more of a non-issue.
I'm not inclined to like compromises (since they make both sides of an argument unhappy) but since the current IC rules were written with a safety margin for a typical max 8 Oz of fuel which is ~7.2 oz (at ~.9 oz per fluid oz) Then I'd think a more sensible compromise would be to only add the difference of a battery that weights more than 7.2 Oz (.9 x 8.0 ) from the weight of a competitors battery for E-Power planes. :!
EricV
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Much ado about nothing, best to leave it alone and not give lawyers any fodder
and by the way I am like most everyone, I use 018 on a 59 ounce stuntship, a 60 size piped stuntship is spongy feeling on 015s ,
so I am not saying this for the advantage of using 015s, that is a non issue for me and most people flying, others use 014 solids
Randy
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I have not personally witnessed a line failure in flight of a stunt model that has already passed a pull test, other than perhaps a model that free flighted across the circle due to a wind gust, and then snapped a line at the opposite end.
Maybe a potential remedy could incorporate two amendments. One - Increase the maximum model weight to 71 ounces (ie. 64 + 7 = 71) at which point the line size requirement increases to .018” minimum (it seems to have been working so far) and; Two - IC flyers self declare their fuel load at weigh in. Yeah, some may report a less than actual fuel requirement, but with the added line stretch of a model over 71 ounces, .015” lines would be more a detriment than an advantage, in my humble opinion.
Be nice, I’m Canadian... (and we now utilize AMA rules...)
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Electric powered ships are definitely being placed at a disadvantage with having to be weighed with their fuel source in place.
Impact to the lines - solid "fuel" battery vs. IC wet ?
Zero difference on takeoff and through at least the first quarter of the tank.
Now that's apples to apples.
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Respectfully, Eric, I was in at near the ground floor of competitive electric stunt. None of my batteries even back then (4,000 mAh packs) weighed anywhere near 1 pound! They were around 10 ounces if memory serves. But that is not the issue I'm "discussing" here. The issue is airborne weight versus weigh-in-room floor weight. A 64 ounce electric model will still be 64 ounces when it becomes airborne; a glow model that weighed in at 64 ounces will weigh significantly more wheat becomes airborne. There is no "fuel" added after the weigh in process in electric; why should glow models be allowed to fly at a weight that is much higher and on thinner lines? No one has answered that question adequately for me. There seems to be a lot of smoke (please pardon the obvious glow power pun...) coming from one camp without addressing my question.
I fully expected a "lively" discussion on this issue, but I certainly don't want it to degrade into a mud slinging contest. Can't we just simply agree to weigh the models at takeoff weight, do the pull test and get on with our fun?
Again, respectfully - Bob
But Bob, your building a straw man that says there is a crisis that needs solving for IC... when there is none, and IC has nearly a century of data under it's belt to prove it. You are asking IC to take a hit to accommodate the new kid on the block... safety margins are built into the current rules to accommodate your straw man and why is that YOU cannot just bend?... Why is it the other guys? Because it is YOU that is asking? I have the highest respect for your accomplishments and sweat equity you have put into the event over the years, but it seems like you think it's your way or the highway, and expected a bunch of accolades to your current request. Well, I'm here to tell ya, it's not a great idea, no matter who suggested it.
AND... I stand by my comments on the early days of E-Power... maybe you had access to cutting edge product and were ahead of the curve, but down in the trenches where I was helping trim/observing "regular" people with their early E-power setups, 15-17 oz was NOT uncommon battery weight to power a 60 size ship in the early days, and great gains have been made since then to reduce that. Eventually, I foresee a time when E-power batteries will be lighter than glow fuel, heck, they are almost there now.
I still stand by my comment that this is a non-event, and if anything, do an offset equation based on the safety margin already built into glow and do an additive for the difference to E-Power depending on battery weight if you MUST do something, not the other way around and have fuel dripping in the 180 building... But that said, I strongly feel that anything you do to raise this with the AMA will have a higher potential to hurt the event in the long run than help it. Leave sleeping dogs lie Bob, that's my .02, and I'm out.
EricV
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Why this all of sudden out of nowhere? I could see this when you were competitively flying but you have retired some time ago and now you want to level the field in the name of safety for a compitition you no longer compete in... You even alerted the AMA to a problem we don’t have... What is really going on here? I don’t understand..
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Hi Eric:
Well, I'm not sure where the vitriol came from, and, no, I'm not expecting any "accolades." Actually I was expecting just exactly what you sent, but not from you. Nothing you wrote even came close to answering my question about why it is so bad to have a level playing field and have the models all weighed at takeoff weight and pulled accordingly. It seems that everyone on the IC side of this discussion is bound and determined to belittle my simple request without actually addressing my questions, and some are making it personal. That's fine; I've been in such situations before. I'm just very surprised to find a personal character attack from you on this. That's fine, too. I won't do the same in return; I still regard you very highly. I don't agree with you, sometimes, but I will never make it personal.
Bob
Personal? Vitriol? I am sorry a strong disagreement feels that way to you Bob. I guess this is what happens in discussions where we only see our own side.
I have seen it written that anything other than glowing praise in the world of Stunt can be taken as an attack, and I do apologize if my comments felt like one.
No offense intended, but I did state facts, I DID answer your questions, even if you refuse to see my answers or discount them as non-answers.
I said I was out, and I think I pretty much am on this subject, but I didn't want to leave you with that bad taste, even though this post probably didn't do much to help that.
Peace! H^^
EricV
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Maybe a compromise solution would be to allow electric models to be weighed without the battery. The pull test would then be based on the weight of the model plus half the weight of the battery. For example, the pull test for an airframe that weighs 55 ounces and uses a 12 ounce battery would be 61 ounces, not 67 ounces. This, of course, would require an extra step at the weigh in process. This would allow the weigh in process of a glow model and the already established line diameter brackets to remain unchanged.
Jason
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Why this all of sudden out of nowhere? I could see this when you were competitively flying but you have retired some time ago and now you want to level the field in the name of safety for a compitition you no longer compete in... You even alerted the AMA to a problem we don’t have... What is really going on here? I don’t understand..
I don't think it is necessary to assign sinister ulterior motives, and in particular, in this case, the effect on competition is literally and exactly *0* - your airplane isn't going to be built any differently, it's not really going to weigh more, so it will fly exactly the same way it does now.
This change doesn't matter enough to competition to make an issue of it. I do object to characterizing the current situation as a safety issue - since we have more than half a century of data indicating otherwise and absolutely nothing has changed about the topic. And we just done doing a fairly good and valid analysis to establish the break points. Going straight to the AMA and declaring a safety problem when there is none, and with no consultation, it irritating, but hardly a unique situation.
But ultimately it is irrelevant and doesn't change anything you would do otherwise.
It alters the post-weigh-in "weight bragging contest", but anyone who has nothing better to do but argue about that really needs to find a new hobby. I recall several notables (whose names I decline to mention) at some TT bragging about being lightest by 1/2 an ounce and another who swore up and down his 67 ounce airplane actually weighed 56, but the scales were wrong. The heaviest airplane at the contest, at 72 oz, won the contest by a large margin.
If anything, I would have expected this change to be deferred until now *because* Bobby is retired from competitive flying - because he didn't want to be seen to be manipulating the rules to his personal advantage. I did the same with the "2.4 GHz proposal"- I probably would have outlawed any form of RC or IR control in the mid-90s, but I didn't want to be seen taking advantage of rule changes to "get Windy".
Brett
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This change doesn't matter enough to competition to make an issue of it. I do object to characterizing the current situation as a safety issue - since we have more than half a century of data indicating otherwise and absolutely nothing has changed about the topic. And we just done doing a fairly good and valid analysis to establish the break points. Going straight to the AMA and declaring a safety problem when there is none, and with no consultation, it irritating, but hardly a unique situation.
Brett
This, and Brett's previous statements, pretty much sum up how I feel about it. I'm not sure why Brett is so eager to attach .015 lines to my plane though. You would think I beat him out of a spot on a US team or something.
While Eric and Doug's statements were blunt, I didn't find them particularly offensive. Maybe I'm a poor judge.... A lot gets lost in text, and you of all people should know that Bob. The question; Why this, and why now is a valid one. I'm also in agreement with Brett on the fact that it makes zero difference, other than a few people's feelings. The electric pilots "fuel" is heavier than my engine, and thier motors are significantly lighter, so some comprise had to be reached, in the name of fairness. That compromise was, electric guys have to carry the battery for weigh in.
If it's really that big of a deal, (and I don't think it is)) I'll compromise again and meet you half way. Add 3.5 oz to my weight, and call it even.
Derek
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Are you saying that just because I'm not actively competing that I should have no say in the event in which I spent 50 years? Please tell me that's not your position, Doug.
Of course that is not my position. I didn't say that either. Maybe I have been out of the loop on this but this all seems to come out of nowhere and to say it needs an emergency change makes it sound as if this is a dire situation.
I still revere this event highly, and I am helping a number of fliers to design, build, fly and compete. I'm looking out for their interests, as well as the interests of many other fliers that I don't actively work with. I speak with many fliers, and this subject comes up very often. Many of them are too worried about being bullied by the "opposition," and keep their silence. I'm not so bashful, and I'm certainly not going to be bullied.
I have seen plenty of stunt bullying over the years. Its not good. Anyone with an active AMA can make a rule change request. Scrutiny of such a change request should not be taken as bullying.
I do see a problem, and I do think that open, civil discussion is needed on this matter. Many who've posted on this thread understand that and have offered up some great suggestions. Please do not try to get all the IC guys to just gang up on me and defame me over a simple question. Better yet, do that; I want to know people's true character, and I want everyone here to see how one group here can go "main stream media" to try and silence someone.
That is nonsense and for you to think I would do that shows me just what you think of me... :(
As far as AMA is concerned, I also have the right to speak with them about my thoughts on any matter concerning safety, and, yes, fairness. You want my guns, too?
Bob
Wow...just wow.
I simply asked you why all of sudden is this such an urgent need and this is the reply.... maybe I am the one being pushed down...
On the topic of safety. There is are no current situations that show a change to the current way the IC planes are weighed at this time warrants a needed change. That is not a very good sentence but I think you get my point. There are no planes snapping off the end of lines due to the lines being being to weak at the beginning of the pattern when the tank is full. It's not happening and hasn't been happening. The history isnt there to say this is a safety issue.
Is it a fairness in competition issue? There are two sides to the coin. IC view and the ECL view. I would say there is not an unfair advantage, imagine that, due to the fact the rules clearly state ECL planes will be weighed with battery on board. IC planes will be weighed with an empty tank on board. If you don't want to take that hit on the scale then don't build an electric plane. :)
The battery 100% charged is the same weight as the battery 20%. Since 80% of the battery is gone at the end of the flight and 100% of the fuel is gone at the end of the flight for IC planes. We could add back 20% of the weight of the stated fuel load to make it fair. That way both models are considered to be sitting at the end of the flight in the same condition with 20% of the fuel load on board.
Now.....what if an ECL flier decides to weigh in with a little battery on board to beat the scales and put in the big battery afterward...... S?P
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Yeah, Brett, there's no way I want to open us for more "exposure" by outsiders than necessary, and I certainly don't want any "additional" constraints put on the event.
I guess I am a bit guilty of just wanting to "level the playing field." There is still in my mind a safety issue, but there is also most certainly a "fairness" issue. Why can we not level the playing field for all concerned - even if it is a "perceived" advantage/disadvantage? Is there a way we can just weigh all the models flown at an event at their takeoff weight and do the pull testing accordingly?
Well, by merely broaching the subject, now anyone can argue that there is a "controversy" over the pull test rules. You created one.
And anyway, as I suspected, this has nothing to do with safety, and everything to do with "fairness" - whatever that means. In this case, it means exactly nothing, because *absolutely nothing will be changed* about how the airplanes are built or how they fly. The effect of this will be to raise the pull test requirement for IC models by around 4 lb. I know for certain, having tested it, that at least parts of my system will take more than 220 lbs (guess where that comes from...) since I put 220 lbs on it and it didn't break. So adding 4 lbs will make *no*, repeat, *no* difference.
If anything, marginal systems will see more stress during the test and be more prone to fatigue failure. Great safety innovation - that's one of the things you have to consider when you define margins for testing parts. If you require a 10x test instead of a 4x test on the flight parts, you create failure scenarios that wouldn't have occurred otherwise.
So changing this will not "level" any playing fields, if anything, at most it might cause an occasional additional IC failure either during test or flight, but not enough to bother worrying about - because you had darn well better have more than 4 lbs of margin on a 40 lb test. Otherwise, *the airplanes will be exactly like they were before* in all respects. So what have you changed from a competitive standpoint?
I could live with the alternative - take the battery out for weighing. It accomplished the "level" goal equally well, by ALSO NOT CHANGING ANYTHING that matters. I guarantee you and no one else is going to be able to take advantage of a 4-5 lb lighter pull test by designing the system to be slightly weaker and in any case, if you save an ounce of control system weight on a 72 ounce airplane and think you can tell the difference, you need a better design.
I am sure that the latter will appeal to you, because then you won't have to report you built a 62 ounce airplane anymore, you can say it is 55. Why that makes any difference is beyond me but I know that this is a point of directed urination during the week. Using that as a figure of merit for construction skills is a relic of 1975, but then again...
Note also that now you have probably *torpedoed* that option, because you claimed it was a safety problem, and it's going to be really hard to go back and argue that to solve your safety problem, you are now going to *reduce* the pull test for electric rather than raise it for IC.
Brett
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I will not go to the AMA to effect these changes; I will work through the CLACB.
Bob Hunt
Well, considering who you are, and knowing that you will do an excellent job of writing the rule proposal, I think you have a good chance of accomplishing your goal, and winning the vote with the CLACB. Congratulations in advance.
My take off weight does change from flight to flight, considering weather conditions, and if I can remember how much fuel to use, so..... We are splitting hairs anyways, aren't we? 😉
Hope you are doing well Bob,
Derek
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I just went to my shop and weighed one of my PA65's with a header pipe, Carbon pipe, a rubber duckie, and a 6 oz typical metal tank (empty). They weighed 18.4 oz. (These are actual parts that came out of my Whitely Shoestring).
Can one of the electric whiz guys please tell me what a typical similar (modern) electric power set up with motor battery and assorted electric gizmos weighs. Please, no guesses, weigh the parts!
I suspect the difference is heavily in favor of the IC system but would like to know how much would have to be added to the IC sys (fuel) to make them approximately equal!.
Thanks,
Randy Cuberly
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Perhaps I have misunderstood the impact of a rule change. In light of the thread on Ukraine lines, the weight cutoff of 64 ounces becomes more interesting. A couple of ounces weight plus for IC, or minus for electric could change who is allowed the 0.016 Ukraine lines.
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Randy,
I’m by no means an electric whiz, but I happen to have some pieces in my shop that would power a typical 60 size electric model. The component weights, in ounces, are as follows:
Motor 6.3
Battery 12.8
Esc 1.9
Timer 0.3
Total: 21.3
You didn’t mention if your weight included the spinner and propellor, so I didn’t include them.
Jason
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Fred you hit it pretty close ...
The issue is the line size break .... some are treating the issue as if some planes have to fly with an increased weight ... a big blob of clay that some have to fly with and others don't ..... the issue is the 64 oz break from 0.015 to 0.018's. Although many say that they wouldn't fly with the smaller lines, they really would like to have the option and those 4 to 6 extra ounces make a difference. A bit extra on the pulltest isn't a deal "breaker". Not being able to take advantage of thinner lines is.
Which brings me to my argument ...
.... since we re-did the rules for electric with the 10g pulltest and kept the line size requirement, we are very much "over specifying" the line safety requirements. 10 g's is a bunch of pull, too much in my opinion, but then on top of that we still specify line diameter, a hangover from ic only. 10g's is enough with no specification on diameter, just like FAI. Keep the 0.015 and 0.018 and 0.021 diameter words as "recommendations only" and not requirements.
... if the rule says 10g's only, then there is no diameter advantage, use what you like. Yes there will be a slight pulltest difference for ic and electric, but the consequences are only in the pull.
The issue here isn't safety, its that everyone wants to hit the sweetspot in weight that will allow smaller lines.
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The issue here isn't safety, its that everyone wants to hit the sweetspot in weight that will allow smaller lines.
I agree that the line size breaks don't make any sense, and I would go with "if it passes the pull test, its OK".
But I slightly dispute the concept that we are trying to hit the magic number to use .015s. After the 2003 NATs, where I could feel my 63 ounce airplane stretching the lines and deflecting the bellcrank at the bottoms of the round loops - on .018s, and Allen Goff's airplane broke away completely, there is no way I am flying a 63 ounce tuned pipe airplane on .015 stranded. And, every time I try it, I find myself having to put control input in about half-a-second early just so the controls move by the time I need them. My airplane flies much better and is much easier to control and more precise when I run on .018s.
Brett
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This, and Brett's previous statements, pretty much sum up how I feel about it. I'm not sure why Brett is so eager to attach .015 lines to my plane though. You would think I beat him out of a spot on a US team or something.
The +0.04 would turn into about a -15.
Brett
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Hi Brett
In 2003 I switched to 0.014 solids in the wind. The fact that 0.015 stretch in the wind is a fact. Yours didn't break though. Alans I think was a shortcut across the circle. Without a diameter specification, 10g's only is plenty safe.
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As I tried to say earlier, I do not think safety is an issue. My only point, and Frank confirmed that point, was that I am not able to fly the .015” lines with my 65 ounce electric plane, whereas an IC model that weighs in at 63 ounces can then add 6 or 7 ounces of fuel and still use the .015”lines. (The weights I just threw out there were examples only). I would like to have the option to try the lighter lines, but under the current rules I can not, and clearly it is not because of a safety concern.
Again, as Frank alludes to, is line diameter even an issue if they meet the 10g pull test? Has there been a higher line breakage percentage at FAI based contests? Don’t think so.
And after all that, I may still very well opt to use the .018” lines to avoid line stretch by the 15 thou lines..., but it would be nice to have the option.
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I agree with the 10g only pull. I have always thought that is a great way to do it. It makes sure the ship is airworthy for the next flight and there is no need to worry about diameter.
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Hi Derek:
Thanks for the kind words. I suspect this is a lot of noise for nothing. Several of my friends who happen to fly electric have groused about the real or perceived inequities of the pull test situation glow versus electric. I was just wanting to voice their opinions as well as my own. Obviously it got out of hand. From here on in I'll only make posts about building and innovation in construction techniques. That certainly can't get me into trouble... :-\
Hope you and your family are doing great. How's the house renovation coming along? Hope also that you have a great flying year and finally take it all home. You are quickly becoming like my favorite NASCAR driver, Chase Elliott. Always second. I'll root for you this year no matter what type of power you have in the nose...
Bob
Hey Bob,
I hope that you will always voice your opinions, as well as those who you consider friends. This is still America, right? In this time of great division, those of us who value freedom need to be able to have vigorous debate. Many of us are on edge, mainly, because we are always defending what seems to be a common sense point of view. Just know, that you are among friends, and don't take offense to strong opposition. It's what makes this country great, and creates friendships that can't be broken. You and I have had many disagreements, but we still connect on the important stuff...
As for the house, construction is ongoing.... We have looked at buying another house, and coming back to this one many times. There really is no rush, and our family is very close, literally and figuratively. Thanks for asking, and thank you for your support. I'm not sure how this year will go, as far as competition is concerned. I haven't had much time for airplanes, with work, and other life stuff, but we will see. I enjoy the fellowship as much as anything else, winning is just a bonus.
Derek
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Hi Brett
In 2003 I switched to 0.014 solids in the wind. The fact that 0.015 stretch in the wind is a fact. Yours didn't break though.
Mine were .018s! If it was that bad with .018, what is going to happen with .015 with 70% of the cross-section? I don't care to find out.
Brett
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I'm gonna poke my head in here.
As I'm seeing things the real result of the proposed change would simply be requiring some to use 018 lines which almost everyone flying one of those behemoths is already gonna do?
Seems like a lot of sturm and drang over minutia.
I must say that I saw no vitriol or denigration in any posts. I can tell you guys that the Free Flight Community is in another battle where a guy who does not and cannot fly an event is trying to initiate rules that are beyond stupid. Be thankful that ukie stuff isn't dealing with that sort of B.S.
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I'm gonna poke my head in here.
As I'm seeing things the real result of the proposed change would simply be requiring some to use 018 lines which almost everyone flying one of those behemoths is already gonna do?
Seems like a lot of sturm and drang over minutia.
The effect of the change itself is trivial to non-existent. It would have been just as good to remove the battery from electrics, which lets everybody go on the same basis - but also has trivial to non-existent effect on competition. The big issue I had with it (specifically, treating this like an emergency safety issue, which is assuredly is not), Bobby is going to now drop. So I have no real objection.
Steve Yampolsky is going to propose removing the line size restrictions (again) and if that passes it makes this change entirely moot.
There is a very unfortunate tendency to immediately suspect everyone of sinister ulterior motives with these things, but for the most case, the motivation is entirely irrelevant, it's either a good idea, a bad idea, or irrelevant. This one is almost irrelevant, with very minor effect in a few corner cases.
Brett
p.s. I got an off-line PM about "new Ukrainian lines". These sorts of lines have been available in various forms for at least 50 years, the latest versions may be better but I have similar lines that originated with the Yatsenkos. As above, you might be able to get away with these and get a small improvement in a few corner cases, but as long as the line size requirements remain, the cases where you get substantial improvement are, I think, pretty narrow.
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Bob, and all...
I have been following this thread during my breaks from the WSR grass circle sprinkler improvement. It got quite boring digging trenches for new sprinkler lines. During one of those mind numbing sessions I got an idea.
Brett is right about all the data we have that the line sizes are right for IC. Based on some of the discussion I realized that the information we need is already available!
For instance, consider a 64 (-) ounce IC plane. Figure it has a 6 ounce tank. So the average fuel load is 3 ounces. So data suggests that a 64+3=67 ounce plane on 0.015 braided lines is safe. To make electric and IC "equivalent" in a safety aspect, a 67 ounce electric plane would be just as safe.
So, to get the equivalence you are looking for, why not have separate line size requirements for electric and IC? Instead of 64, electrics would be 67. The other "break" points would also be slightly higher for electric. The pull test would be unaffected by this as it would still be 10x of the weight.
Does this not get the equivalence you are looking for Bob?
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Yep , and a seperate devision for Elec. in intl. comp. S?P S?P and a CONSTRUCTORS Championship ( Make ) seeing its no longer ' Home Made .
maybe . We can get too carried away about ' Equality ' . If All People were equal , Adolf Hitler , Attila the Hun , Col. Idi Amin ( curtosey the British Army ) LL~ :-[ :o
and a few otheres , would bbe equal to say Muhatma Coat Gandi , Mother Tarresa , John Lennon , and Hillary Clinton. What, wrong group there )
LL~ :-X ;D
Parity and Equality , maybe . but other things to consume thought , thanks .
Have a book of quotes , one of which is " Anyone who thinks everone is equal is clearly insane "
Biblicly its ' Equal in the Eyes of God ' which aint neccesarily ' The Same ' .
Also as EVERYTHING was CREATED at the Beginning of Time ! , some ' beings ' have been / become more aligned ,
than say the TV producers and Hollywood . H^^ n1
Anyway . the Pre Advertising , 60s Grand Prix , when it was more a Gentlemans Sport . Than a COMERCIAL RACKET ,
the rules were less overwhelming and restricting .
The Pre War ' 750 Kilo ' formular had 200 mph plus BACK THEN .
Nailing the big jump in dia. at 65 Oz or whatever it is , if it hasnt been done , should be .
Again I think it was sore loosers who put the 2 mitre span restriction in FAI as they couldnt do a P W B-17 themselves .
A WEIGHT RESTRICTION O.A. of say 2 Kilo , might have been sane. a Span Limit is a Restriction .
Incidently , if you full your plane with helium or hydrogen , itll still have a MASS / Inirtia of Its Weight , even though ' negative ballasted .
Really I think ELECTRIC is a SEPERATE Formular Matematically , regarding many things , its pulling the I.C.E. stuff around with it ,
in the regulations , as the 4 strokes did with capacity . Not that it matters a stuff .
As long as it dosnt bind things up rather than stimulate actual ( aerodynamic ) progress .
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The Can Am Racing was the most Rule Free & Spectacular . ( The Kiwi's Winning . VD~)
(http://4.bp.blogspot.com/-3tEvLjONxog/To6hvSCX_kI/AAAAAAAAAus/KJk18eVPNr0/s1600/McLaren-M6GT-Chevrolet_11-a.jpg)
We dont need to get to carried away and pedantic , until the prize moneys equal to Wimbleton . Wrong Flushing Meadow :( apparently .
( Thats a road car . The Real one sat at McClaren Motors . The Bloke said he couldnt find the keys , when I asked if I could have a drive )
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As an interesting aside, when we were pulling based on engine sizes, a lot of us got 45 lb pull tests on 45 ounce ST46 airplanes - 16Gs instead of 10.
Brett
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(Clip)
Which brings me to my argument ...
we are very much "over specifying" the line safety requirements. 10 g's is a bunch of pull, too much in my opinion, ------
(Clip)
Hi Frank,
I am not really taking exception to any of your statements on this thread. One point though regarding the "adequacy" or efficacy of the 10G pull test. Yes, it is a lot, but well within the bounds of properly built control systems with the specified line diameters. However, I offer two observations. Several years ago, I attended the Nats and was helping one of the competitors on the top 20 day. He has been in the top 5 before and is an excellent builder. One of his leadouts failed on the pull test not even when it was at its required 10G pull test. The leadout failed where it had rubbed against the internal landing gear wire after countless flights. He only lost the leadout wire and maybe some slight damage to the controls when the one line failed. If this had happened during the next flight, the entire model would have been lost.
The 10G pull test requirement is to test the control system with a certain safety factor even if one line fails in flight. I lost a cable in the control handle just before an official flight at VSC several years ago. The up cable failed on an outside square. The model then continued to do outside loops until the inevitable happened and pancaked upside down on the pavement. Sort of gave a helpless feeling. The one line/cable still kept the model in the circle. Maybe a pull test prior to that practice flight would have shown that cable was ready to let go before I lost the entire model.
Keith
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There is doubt that we have accurate history on IC airplanes. Possibly the separate pull test categories could work. But, as said by many the safety factor on lines is already there.
Personally I have no use for solid lines. I've been doing this for 50 years and the only line break I have ever had was with solids! Legal diameter, and no free flighting across the circle with a snap at the end. They were not old lines either.
Then adding the solid lines sticking in humid weather and that they are almost impossible to keep clean, I just don't trust solid lines.
That aside, 10G pull is probably the best way to go.
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The 10G pull test requirement is to test the control system with a certain safety factor even if one line fails in flight.
It is certain, and well-known - the pull test is a factor of about 2 over the load of one line in steady-state flight, which not coincidentally is also about half the industry-standard test strength of the line. The pull is about 2.5Gs, and the test is 10Gs, so about a factor of 4 over the flight loads.
I think that is about right, it weeds out the worst cases where it is about to fail in-flight, and still provides restraint of the model with some margin if one line does fail in flight - without imposing a significant performance burden. It's also consistent with the very extensive historical range of experience, with some refinement that prevents the sort of thing I mentioned above (16G pull tests due to a mere quirk in the rules).
Brett
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Which brings me to my argument ...
.... since we re-did the rules for electric with the 10g pulltest and kept the line size requirement, we are very much "over specifying" the line safety requirements. 10 g's is a bunch of pull, too much in my opinion, but then on top of that we still specify line diameter, a hangover from ic only. 10g's is enough with no specification on diameter, just like FAI. Keep the 0.015 and 0.018 and 0.021 diameter words as "recommendations only" and not requirements.
I would be curious what you would consider a pull that is not excessive. For years, we were pulling quite a bit more than 10Gs in many cases, so if anything, the 10G VS engine size change probably made it go down, not up, for most current airplanes. I would be pulling 45 lbs under the old rules, now I pull 41. I kind of like a factor of 2 as a goal and a reasonable compromise.
I think we all agree on the need for line size requirements, i.e, there is no engineering justification for requiring particular sizes as long as you don't also specify the strength (which we DO NOT want to do, since it's effectively impossiblel to check in the field). But I think that the idea that you are shooting for 63 ounces or whatever so you can use .015s is not much of an argument - although I won't be rushing to stop anyone from shooting themselves in the foot that way.
Brett
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When I read the initial post of this thread, I had to check its date twice: I was pretty sure it had to be April 1.
Mind you, I am accustomed to a sport that has half a dozen or so flyaways per contest. Yes, I was there at the horrid Allen Goff Nats flyaway. I was on Circle 3 flying a 69 oz. airplane on .015" cables.
If you want a rule change, I suggest one that provides adequate safety with reduced bother. Dropping line size minima should accomplish that.
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Yep , and a seperate devision for Elec. in intl. comp. S?P S?P and a CONSTRUCTORS Championship ( Make ) seeing its no longer ' Home Made .
maybe . We can get too carried away about ' Equality ' . If All People were equal , Adolf Hitler , Attila the Hun , Col. Idi Amin ( curtosey the British Army ) LL~ :-[ :o
and a few otheres , would bbe equal to say Muhatma Coat Gandi , Mother Tarresa , John Lennon , and Hillary Clinton. What, wrong group there )
LL~ :-X ;D
Parity and Equality , maybe . but other things to consume thought , thanks .
Have a book of quotes , one of which is " Anyone who thinks everone is equal is clearly insane "
Biblicly its ' Equal in the Eyes of God ' which aint neccesarily ' The Same ' .
Also as EVERYTHING was CREATED at the Beginning of Time ! , some ' beings ' have been / become more aligned ,
than say the TV producers and Hollywood . H^^ n1
Anyway . the Pre Advertising , 60s Grand Prix , when it was more a Gentlemans Sport . Than a COMERCIAL RACKET ,
the rules were less overwhelming and restricting .
The Pre War ' 750 Kilo ' formular had 200 mph plus BACK THEN .
Nailing the big jump in dia. at 65 Oz or whatever it is , if it hasnt been done , should be .
Again I think it was sore loosers who put the 2 mitre span restriction in FAI as they couldnt do a P W B-17 themselves .
A WEIGHT RESTRICTION O.A. of say 2 Kilo , might have been sane. a Span Limit is a Restriction .
Incidently , if you full your plane with helium or hydrogen , itll still have a MASS / Inirtia of Its Weight , even though ' negative ballasted .
Really I think ELECTRIC is a SEPERATE Formular Matematically , regarding many things , its pulling the I.C.E. stuff around with it ,
in the regulations , as the 4 strokes did with capacity . Not that it matters a stuff .
As long as it dosnt bind things up rather than stimulate actual ( aerodynamic ) progress .
Matt : Please allow me to suggest that you start in earnest, like today, to go play elsewhere.
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Instead of "what size tank" How much fuel do you take off with? would be better.One of my planes has a 6 ounce tank and I use 4 ounces per flight.
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. Why should we not also accept their word about tank size? If someone is flying a model powered by a .75 and they claim they have a four ounce tank on board, well...
Just a suggestion.
Bob Hunt
My .77 needs 2,8oz per flight Bob..:) L
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Goodness,
There is a lot of heat over something which can be handled simply which would affect all gas flyers equally and with a fair approximate weight not too far from actual weight. Simply add one ounce for each .10 of displacement to the scale weight of the airplane. My F-51,s would add 6 ounces to its scale weight. My Bearcats and Critical Mass would add 7 ounces to their scale weight. Fox .35 airplanes would add 3 ounces and so forth.
If Brett and Bob think think that we have a problem with catching cheaters by adding unnecessary complication to the rules, how would they respond to flyers removing tipweight prior to being weighed in? We can't guard against every possibility for cheating and shouldn't dignify the efforts of cheaters by making rules solely to catch them..
Al
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This may be a moot point, but at only one contest in the last 20 years has this actually been done, mainly checking with a micrometer, the size of my flying lines during the pull test and this was at St Louis ten years ago. Never before nor since has anyone ever checked my lines for size. Just pulled based on engine size and now pulled on the models weighed in weight, on some very inaccurate scales in most cases, out side in the wind with the weight all over the place. FWIW D>K
The point about tolerances is right on the mark, the rusty, 60-year-old fish scales commonly used for pull tests and sometimes for weighing the airplane is hardly precise enough to consider the fuel mass variation. Take the stated bias and scale factor stability of a common post office scale when used outdoors when it is 105 degrees, or when it is 45 degrees, and then multiply that by 10. Then throw +-5 lbs at best for a 60-lb fish scale.
However, the line sizes are spot-checked at times, almost every year at the NATs, and not uncommonly at local contests. Just like everything else, if there is a clear rule, people will follow it whether they might be able to get away with cheating most of the time. If nothing else, if you get caught cheating just once, your reputation is bad forever, because everyone will find out - and the entire point of the event is to gain the respect of your fellow competitors. But for the most part, people will not cheat because they are basically honest, particularly so in the stunt event.
Brett
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My .77 needs 2,8oz per flight Bob..:) L
This I gotta see! LL~ LL~ LL~
Jerry
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Goodness,
There is a lot of heat over something which can be handled simply which would affect all gas flyers equally and with a fair approximate weight not too far from actual weight. Simply add one ounce for each .10 of displacement to the scale weight of the airplane. My F-51,s would add 6 ounces to its scale weight. My Bearcats and Critical Mass would add 7 ounces to their scale weight. Fox .35 airplanes would add 3 ounces and so forth.
Al
That’s a good idea. Simple and straight forward.
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There is a lot of heat over something which can be handled simply which would affect all gas flyers equally and with a fair approximate weight not too far from actual weight. Simply add one ounce for each .10 of displacement to the scale weight of the airplane. My F-51,s would add 6 ounces to its scale weight. My Bearcats and Critical Mass would add 7 ounces to their scale weight. Fox .35 airplanes would add 3 ounces and so forth.
Yes, that would be a potential "solution". That of course presumes that there is a problem to solve in the first place (which, given the other tolerances, there isn't). And as soon as you did that, the people who are worried about the problem will want to either measure everyone's engine (he said it was a 46 but it's really a 75), and/or argue that 7.5 ounces is not enough for a 75, since David runs about 8.5 ounces in his, not 7.5.
If this was a real safety issue, then it might be worth considering, but when you have the same airplane being weighed from 62 ounces to 67 ounces (which is the range I have gotten over the last few year (and its really 66.5)) and using a rusty fish scale with a calibrated eyeball deciding when to release the pull, these variations are all in the noise. To significantly improve it you would need some sort of calibration program for the measuring equipment, which we don't need to do nor are we going to do.
This is more about the electric fliers feeling aggrieved over having to weigh with the battery in. A simpler solution would be to allow them to weigh the airplanes without the battery, and counting on the margin to cover the difference. I am not sure what Frank has in mind for a "reasonable" pull test, but his point is that 10G is too much. Leave out the battery, and it's 7.5gs or something for electric, and about 1.6x over the flight loads instead of the (by design) 2x. I can live with that, it's not like IC airplanes are flying off the ends of the lines with an *actual* 1.7x (once you add 8 ounces of fuel).
Brett
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Im looking at this in a little different perspective, as I see a tie with the Ukraine line thread. My electric plane comes in at 63.5 oz ready to leave the ground. Im waiting for the one time im weighed in and im over. So, Im Flying the 4 strand 016 lines. The day i come in overweight my lines are now illegal. Yet, the guy with the IC engine that weighs 62 oz.dry, fuels his plane and takes off at 67 oz legally with 016 lines. Thats my issue. I couldnt care less if me or IC Joe pulls an extra 5 pounds .
My 2 cents
Thanks
Tom
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It is 2018 and we are still using stainless steel wire? How long has stainless steel wire be around? Didn't we at one time use wooden bellcranks connected to stainless steel wire? If you have noticed we don't use wooden bellcranks anymore but we are still using stainless steel wire. We have modern and sophisticated model airplanes connected to old technology. Do you realize all the technological gains made in fishing line industry? If we used modern technology to connect to our handles and airplanes we all could benefit from using thinner and better lines. Wouldn't the “line break” point be elevated to the point where both IC and electric models could both be flown on the same thin lines because there actual take off weight would be well below the “line break” of the same thin lines?
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Although I am new to stunt, I do not understand why we would not have the same playing field? To me it should be equal. I did like Paul’s idea about adding weight to equal the playing field. This is much like NASCAR they make all the cars weigh the same and in the top series’s they also figure the weight of the driver so that they level the playing field. The lower ranks they simply weigh the car with the driver in it and make all cars equal for the most part. This is just my opinion, I agree with what Bob is trying to do and I think it is the right thing to do.
Thanks
Joe
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I would be more in favor of weighing/pulling the electric battery free, or a little less knowing we have a substantial safety factor built in. I have nothing under 70 ounces and always use .018 and always feel like I need to tie my butt to a tree to pull the planes. It will take it for sure but I can't see having to pull any more when it has nothing to do with me. I'd rather make whatever adjustments the other direction.
Dave
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I would be curious what you would consider a pull that is not excessive.
But I think that the idea that you are shooting for 63 ounces or whatever so you can use .015s is not much of an argument - although I won't be rushing to stop anyone from shooting themselves in the foot that way.
Brett
I don ‘t necessarily feel that 10 g’s is too much, but ten 10 g’s with also an imposed “stair step” line diameter minimum is over specified I feel. The “stairstep” diameter specification is a remnant of the previous ic rule. Nominal flying g’s are 3, a runaway ic is probably about 5 g’s. Simply a 10 g pull is satisfactory.
At present I’m shooting for 63 oz’s …. Yes, not so much to use 0.015 stranded, although some planes will tolerate them, but to take advantage of the 0.012 solids. 10g pull before you fly and you’re ready to go. Maybe a =/- delta for ic/elec if needed.
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At present I’m shooting for 63 oz’s …. Yes, not so much to use 0.015 stranded, although some planes will tolerate them, but to take advantage of the 0.012 solids.
.012 SOLIDS! Wow, that is not something I would have contemplated as an issue.
Brett
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It is 2018 and we are still using stainless steel wire? How long has stainless steel wire be around? Didn't we at one time use wooden bellcranks connected to stainless steel wire? If you have noticed we don't use wooden bellcranks anymore but we are still using stainless steel wire. We have modern and sophisticated model airplanes connected to old technology. Do you realize all the technological gains made in fishing line industry? If we used modern technology to connect to our handles and airplanes we all could benefit from using thinner and better lines. Wouldn't the “line break” point be elevated to the point where both IC and electric models could both be flown on the same thin lines because there actual take off weight would be well below the “line break” of the same thin lines?
GSUMP lines are something being experimented with in other venues, so far, no one has proposed them for stunt (along with the necessary engineering evaluation) and termination requirements. I don't know enough about them to do it myself.
Stainless steel stranded lines have the advantage of 70-ish years of experience with very-well-understood characteristics. That is not irrelevant to the discussion.
Brett
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Seems to me that this issue is mainly centered on the line diameter requirements. I agree with Brett that a few pounds, more or less, in the pull test doesn’t matter very much. However, the line diameter requirement does have an effect on the way the plane flies. Whether you like the reduced drag of smaller diameter lines or the stiffer more responsive feel from larger diameter lines, shouldn’t it be left up to the pilot to decide what they like?
Rick
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Seems to me that this issue is mainly centered on the line diameter requirements. I agree with Brett that a few pounds, more or less, in the pull test doesn’t matter very much. However, the line diameter requirement does have an effect on the way the plane flies. Whether you like the reduced drag of smaller diameter lines or the stiffer more responsive feel from larger diameter lines, shouldn’t it be left up to the pilot to decide what they like?
Rick
Yes, especially if the smaller diameter lines are stronger (or just as strong), and stretch less as in the case of some of the currently available stuff!
Unfortunately, most safety provisions while suggested by engineers are most often decided by lay politicians!
Randy Cuberly
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Point taken, Lauri! H^^
Bob
Bob,
Have you ever seen one of Lauri's engines. They are a masterpiece of machining and they run extremely well.
Keith
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One thing that is lost in this discussion, is that , yes, an IC model takes on 4 to 8 ounces of fuel for take off, typically. But as soon as the engine is started, that weight starts coming off and continues to come off until the end of the flight. Electric models weigh the same throughout the flight. Yes, that is all very obvious but I'm gonna guess that whoever was involved in the new pull test rules took that into consideration. When does everyone think that the most stress is on the lines, the beginning, middle or end of the pattern? Some may say that the most stress is in the latter half of the pattern after the triangles, and by that point, about half the fuel/weight or more is gone. When it comes to the idea of fairness or who has an advantage, I would say it is all in the electric court. They can build a model that weighs the same and balances the same throughout the flight. I think that would kind of "balance" against having to pull a few pounds more. Some where in the concept of trying to get an electric model weight down to where you can use smaller diameter lines is the right size/wing area/wing loading to achieve that. The answer to that question may lay entirely in a new model design to best use the consistent dead weight that is the electric power plant. So far, most people are just converting existing design with slight modification to mount the equipment. With as much success that the electric stunt model has had, I feel that there is no disadvantage to the extra weight. You just have to learn to work with what you have and design an air frame to give you want you want, not just "build a lighter model." I hope that makes sense.
Type at you later,
Dan "Gimme My Nitro" McEntee
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Seems to me that this issue is mainly centered on the line diameter requirements. I agree with Brett that a few pounds, more or less, in the pull test doesn’t matter very much. However, the line diameter requirement does have an effect on the way the plane flies. Whether you like the reduced drag of smaller diameter lines or the stiffer more responsive feel from larger diameter lines, shouldn’t it be left up to the pilot to decide what they like?
Rick
I agree 100% The pull test should be the qualifier and you should be able to fly on sewing thread if it will pass the pull test. I for one would like to see a bit more lbs added to the test. When these big heavy planes lose tension overhead and hit the lines on the other side of the circle they pull a whole lot more than any pull test. Why do you think we have to wear that sill noose around our wrists. Most everything I fly has a floating bellcrank and properly mounted it can take double the required test. I say up the pull test and drop the line size requirement entirely but that's just me and I could be wrong!
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This I gotta see! LL~ LL~ LL~
That is perfectly plausible, he is using very advanced techniques to maximize the specific output, and can do it because he is building the engine from scratch. I also expect that he is running a very efficient propellor. We take existing engines and figure out how to make them run, and sometimes that means using very inefficient systems and just building a bigger fuel tank.
Brett
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While I really don't care even a little bit about making it either "fair" or "equal" for electron burners, I am somewhat shocked that you all seem to agree and accept that one fluid ounce of high alcohol content fuel would equal one ounce of weight. It seems to me like the proposal is for one fubar to replace another fubar in the rules. Since I have no idea how much your battery measures in fluid ounces...leave it alone. y1 Steve
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While I really don't care even a little bit about making it either "fair" or "equal" for electron burners, I am somewhat shocked that you all seem to agree and accept that one fluid ounce of high alcohol content fuel would equal one ounce of weight. It seems to me like the proposal is for one fubar to replace another fubar in the rules. Since I have no idea how much your battery measures in fluid ounces...leave it alone. y1 Steve
Steve our methanol is something like .82 oz. weight per ounce fluid-less oil. For discussion purposes it's close enough 1-1. What is strange about that is I can readily feel 1/2 oz. of lead nose weight on the planes. I don't seem to notice losing 7 oz. in the nose while I fly.
Dave
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While I really don't care even a little bit about making it either "fair" or "equal" for electron burners, I am somewhat shocked that you all seem to agree and accept that one fluid ounce of high alcohol content fuel would equal one ounce of weight. It seems to me like the proposal is for one fubar to replace another fubar in the rules. Since I have no idea how much your battery measures in fluid ounces...leave it alone. y1 Steve
I was figuring about 6 ounces for my 7.1 ounce tank, which seems pretty close to me.
Of course, if you accept the concept that the tolerance stackup leads to about a 5 lb tolerance in the actual pull test, the difference is completely lost and moot.
Brett
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Steve our methanol is something like .82 oz. weight per ounce fluid-less oil. For discussion purposes it's close enough 1-1. What is strange about that is I can readily feel 1/2 oz. of lead nose weight on the planes. I don't seem to notice losing 7 oz. in the nose while I fly.
Try doing the hourglass first.
One of the things I notice when flying Classic airplanes, even with 4 ounces of fuel, they go from too sluggish to too sensitive from beginning to end because the tail volume is so small.
Brett
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I think we did the right thing a few years back when we retired the pull test based on engine displacement and introduced the pull test based on model weight. However, we ALSO defined minimum line sizes at different weight points.
The point that Bob made in his original post was essentially that we did not quite complete the deal. The criteria we use for weighing electric models makes perfect sense. We would have an awful hard time explaining to a third party why we would not treat an IC airplane by the same criteria.
However, I want nothing to do with bringing fueled models into the "180" building for weighing!
Since our minimum line sizes and pull test are based on weight, there is an opportunity to simply use DIFFERENT weight tables to drive the minimum line size requirement. I suggest using the current weight schedule for electric models with batteries installed and use a different (lighter) weight schedule for IC powered models with empty fuel tanks. To show how that would work I prepared the example below, based on modifying the table we have in the rule book.
We could argue (discuss) whether the weight differentials correct, but I think something in this format is a workable solution that would be easy to administrate. NOTE: had a devil of a time getting column alignments - please pardon the mess!
Electric Powered IC Powered Required Minimum Diameter of Each Line Pull Test
w/Battery Installed w/Fuel Tank Empty Single Strand Multi Strand
(ounces) (ounces) 1 Line 2 Lines 2 Lines Electric IC Powered
--------------------- ---------------------- ------- -------- -------- --------- ------------------------------------------
0 - 14.0 0 – 12.0 0.014" 0.008" 0.008" 10 g 10g based on model weight plus 2 oz
14.1 - 40.0 12.1 – 36.0 0.014" 0.010" 0.012" based on 10g based on model weight plus 4 oz
40.1 - 64.0 36.1 - 58.0 0.014" 0.012" 0.015" model 10g based on model weight plus 6 oz
64.1 - 80.0 58.1 - 72.0 0.016" 0.014" 0.018" weight 10g based on model weight pus 8 oz
80.1 - 123 72.1 - 113 0.021" 0.018" 0.021" 10g based on model weight plus 10 oz
I admit the weight differential would over-compensate for the fuel load on Lauri's magnificent engine!
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It would seem that the airframe on and electric airplane, especially the fuselage could be build significantly lighter than on an IC airplane. There is far less vibration stress on the airframe. Wood in the fuselage could be thinner and even lighter. I would think less hardwood and plywood would be required.
I know for a fact that a couple of the nicely finished electrics here in Tucson weigh less than some of the similar sized IC airplanes. That would mean that the airframes would have to be very light.
John Callentine's 650 sq in electric for instance weighs 61 oz with battery installed. most of the similar sized IC planes here weigh at least that much with no fuel on board!
Or am I all wet about this! I have very little real electric experience but it just seems logical that they could be built lighter!
Randy Cuberly
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One thing that is lost in this discussion, is that , yes, an IC model takes on 4 to 8 ounces of fuel for take off, typically. But as soon as the engine is started, that weight starts coming off and continues to come off until the end of the flight. Electric models weigh the same throughout the flight. Yes, that is all very obvious but I'm gonna guess that whoever was involved in the new pull test rules took that into consideration. When does everyone think that the most stress is on the lines, the beginning, middle or end of the pattern? Some may say that the most stress is in the latter half of the pattern after the triangles, and by that point, about half the fuel/weight or more is gone. When it comes to the idea of fairness or who has an advantage, I would say it is all in the electric court. They can build a model that weighs the same and balances the same throughout the flight. I think that would kind of "balance" against having to pull a few pounds more. Some where in the concept of trying to get an electric model weight down to where you can use smaller diameter lines is the right size/wing area/wing loading to achieve that. The answer to that question may lay entirely in a new model design to best use the consistent dead weight that is the electric power plant. So far, most people are just converting existing design with slight modification to mount the equipment. With as much success that the electric stunt model has had, I feel that there is no disadvantage to the extra weight. You just have to learn to work with what you have and design an air frame to give you want you want, not just "build a lighter model." I hope that makes sense.
Type at you later,
Dan "Gimme My Nitro" McEntee
My 60s sized ships use just under 5 ounces for the VECTRA and just over 5 ounces for the KATANA , average that weight it is 2.1/2 ounce . I think t s funny so many people think we all are using 7 to 8 1/2 ounces of fuel, and some want to add a minimum of 6 ounces to your IC plane?
I agree if we fly the 2 type planes together the field should be level, HOWEVER as I have been told by several people flying Electric, they have a huge set of advantages over IC as it stands now.
Like the advantage to start the motor and the pattern, Big one for Electric
Run time, big advantage when you can get every flight almost to the second, advantage electric
Program the computer controlled motor to help you with certain maneuvers, like a burp, followed by 5 seconds of FULl Blast power to increase the speed to help with placing the plane better where you want it on landings.
Being able to programs in more or less simulated 4/2 break instantly.
Being able to have the motor shut itself down automatically if you hit the prop on the ground on takeoff
There are several more but the point is made, and not to mention being able to get much more practice at many more sites. And there is NO telling what else people will be doing in the future ,with computer controls to help fly your maneuvers
I develop, sell, planes and equipment for both systems, and I would not want one to have more advantages over the other, no matter what is motivating the plane. In my mind all is NOT level now.
Randy
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I agree if we fly the 2 type planes together the field should be level, HOWEVER as I have been told by several people flying Electric, they have a huge set of advantages over IC as it stands now.
Like the advantage to start the motor and the pattern, Big one for Electric
Run time, big advantage when you can get every flight almost to the second, advantage electric
Program the computer controlled motor to help you with certain maneuvers, like a burp, followed by 5 seconds of FULl Blast power to increase the speed to help with placing the plane better where you want it on landings.
Being able to programs in more or less simulated 4/2 break instantly.
Being able to have the motor shut itself down automatically if you hit the prop on the ground on takeoff
I more-or-less agree with this assessment, and to me it is clear that the advantage will grow with time and experience. We have about 70 years of IC engine experience, and 30 with the definitive and probably final configuration. They are more-or-less optimized at this point and at least a fair number of people are able to achieve nearly ideal performance most of the time.
Having said all that, I still think that IC in perfect shape has advantages over electric in the current state of development in a few conditions, specifically, heavy but smooth wind. Electric has advantage in most other conditions, particularly light to dead air, or light turbulent air.
I don't think the rules should drive you to a solution, but at the same time, if something its better, it's better, and trying to change the rules to even up the odds by favoring one over the other is something I wouldn't have much enthusiasm for. Electric is not the sort of leap forward that happened when we went from ST60s and the like to tuned pipes, and we didn't change the rules to try to help them keep up (or as Windy suggested, start a different event to separate them out).
The issues discussed here are really just about feeling aggrieved, with some justification, but don't make any difference from a competitive or engineering standpoint. It's not really worth fixing, but by the same token it doesn't hurt anything if they are "fixed".
The line size requirements don't make a lot of sense a long as we are weighing the models and pulling 10gs. and if we can, we should get rid of them. Last time I broached the subject, I was told they would never go away, but maybe that has changed.
Brett
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good morning i have been following this thread as i wait for ome weather to go testing my latest model i fly f a i so if you pass the pull test you can use any size line you care to but what causes me some concern is that only oficciall flights are pulled for a pull test to be valid every flight at a contest ought to be pulled including all test and practist flights if their are any safty concerns other wise to me it seems pointless roy
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As I wrote earlier, I think this is much ado about nothing, just let people pull 10 gs and run whatever lines they want, as long as they test OK
Simple solution, it will work, and gets us past calling IC guys bullies, and insinuating they are liars , that we DO NOT need, and does not serve us well
Randy
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Without a doubt this is a simplest and best solution to the problem at hand. 10g pull only.
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I disagree. In general people are smarter than you think. FAI flyers don't seem to have a problem.
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I disagree. In general people are smarter than you think. FAI flyers don't seem to have a problem.
Yep this is right the rest of the world has been doing this for many years, and you will not find anyone flying a 64 ounce ship on 008s, I think you would be hard pressed to find one flying on 012s, Even 015s are lines I personally would not use on a 64 ounce 60 sze ship, too spongy, better control and feel is much more important than the .003 difference, and if you have to , you can run 014 solids.
I do not think 008s would even pass the 10 G pull test, and if you are doing 10 G pull test, then your lines break while flying pulling 3 Gs, something else seems wrong
Randy
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In all my time in this sport, the very few failures I’ve seen were all, save one, were where the wire got damaged, mostly where the ends were made by either working back and forth at a hard point where the cable exits the ferrule or a kink. The only other failure was a brand new set of Sullivan’s from years ago shredded in the middle on the first flight- an obvious flaw in the cable. The line weight really wouldn’t have mattered very much other than the heavier line will hold with more damage not yet seen. Line condition I think is more important than weight. You can only hope a pull test will find the weak point on the ground.
Dave
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Brett you may not be aware of this per your comment but Gsump lines have been submitted by Tom Hampshire for a rule change to allow for the use in CLPA on 5/2/18. Proposal and initial vote links. Looks like it passed initial vote 6 to 5. https://www.modelaircraft.org/files/CLA19-02.pdf https://www.modelaircraft.org/files/CLAerobatics2018InitialVoteResults.pdf Dennis Adamisin, Bob Hunt, Phil Cartier, and Frank Williams also signed the proposal.
"Gsump lines"? I assume you mean Spectra or MicroDeema fishing lines, but I've never heard those referred to as "Gsump". I have not tried either, but I know there is some information in the AMA rulez about how they are to be fastened at the end....but there have been reports that it doesn't work. I figured that there would need to be some improvements in the rules there before further applications would be allowed. But maybe I figured wrongly. D>K Steve
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I apologize for posting bad info. I didn’t look at the date close enough. It appears this proposal was dropped. So I deleted the post.
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In all my time in this sport, the very few failures I’ve seen were all, save one, were where the wire got damaged, mostly where the ends were made by either working back and forth at a hard point where the cable exits the ferrule or a kink. The only other failure was a brand new set of Sullivan’s from years ago shredded in the middle on the first flight- an obvious flaw in the cable. The line weight really wouldn’t have mattered very much other than the heavier line will hold with more damage not yet seen. Line condition I think is more important than weight. You can only hope a pull test will find the weak point on the ground.
Right - we are hardly treading new ground here. This sort of issue is a common one in the aerospace industry - trading off increased safety/margins for performance. You can't build spaceflight pressure vessels to the same margins as a stationary steam boiler, for example.
I think that the line pull test/line size requirements follow common safety factor rules for performance (roughly a factor of two after a single failure) and that's a good standard to use in this case. The previous chart had some real anomalies, in both directions, so the latest change was to even that up. It just happened that the most critical break point fell right in the middle of the current range of airplane weight at 64 ounces. That's what the engineering said, so that's what it is.
If people are willing to move past the requirement (apparently mandatory in the past, maybe not mandatory now) line size requirements, then the issue essentially goes away - from an *engineering* standpoint.
I dispute the "fairness" aspect as it appear to have more to do with looking bad to some people for some reason. Weigh the airplanes with or without the battery or fuel, you are barely affecting the safety due to the other tolerances in the system, and if if makes someone feel better to say the airplane weighs 55 ounces than 64, then fine with me. It's entirely cosmetic, and if someone is all hot to fly their 60-sized electric at a liftoff weight of 64 ounces on .015 stranded, or .012 solids, breaking loose and hitting someone is not the biggest issue.
Brett
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Just out of curiosity, has anybody ever devised a method of measuring line pull in the air? Other than combat I have only seen two in flight line failures and both of them had just passed a pull test. We pull both lines together yet the "ah sh**" situation usually hits one line full force. If you don't break a line you sure do put a lot of stress on the bellcrank and flap horn. I am sure there is a reason but why don't we use "stops" on the bellcrank to limit movement if one line is yanked. How many of our ships could stand the pull test if each line were done separately, even at lower lbs.
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I have also been curious about measuring the line pull in the air. With the proper equipment (instrumentation?) I suppose it could be done if someone wanted to go thru the steps. But, is it worth the time spent? Maybe, for some, but for me, it is easier to do the math. I know the weight (mass) of the plane, the radius of the circle, and with a standard lap time (5 seconds, give or take a few tenths?), I plug the numbers into the formula.
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I apologize for posting bad info. I didn’t look at the date close enough. It appears this proposal was dropped. So I deleted the post.
No need to delete your post. The basic proposal to allow GSUMP lines (spectra) did pass the initial vote of the Contest Board 6-5, where a simple majority is needed to pass the initial vote.
Keith
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Just out of curiosity, has anybody ever devised a method of measuring line pull in the air? Other than combat I have only seen two in flight line failures and both of them had just passed a pull test. We pull both lines together yet the "ah sh**" situation usually hits one line full force. If you don't break a line you sure do put a lot of stress on the bellcrank and flap horn. I am sure there is a reason but why don't we use "stops" on the bellcrank to limit movement if one line is yanked. How many of our ships could stand the pull test if each line were done separately, even at lower lbs.
A stop on the bell crank wouldn't limit the force on the line when it hit the stop. It would simply make it occur sooner...and possibly more often!
Further, if one line breaks when it hit the end of travel the other usually does NOT. I have see stunt planes do a dozen or more loops on one line before crashing or in a couple of cases run out of fuel! Of course if it's the up line that breaks there is probably not enough time left before the crash to even blink....still NO flyaway!
I'm of the opinion that all of this is a non problem but would be highly in favor of a simple pull test requirement like the FAI has...If it passes the pull test...It flies! Simple and effective in my opinion.
In other words a line diameter requirement is unnecessary. If you can find lines that are strong enough to pass the pull test requirement why should anyone besides the pilot care if they stretch, etc, etc, etc...
What's next lines can't be too shiney because they'll blind the pilot or judge... HB~> HB~> HB~>
Randy Cuberly
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A stop on the bell crank wouldn't limit the force on the line when it hit the stop.
Randy Cuberly
I was thinking more in line with damage to the rest of the control system if there is no practical limit on bellcrank movement. You are right about the 2nd line not usually breaking but once the loops start there is little or no centrifugal force to break it. There is however a very valid reason to keep the line size rules. Without stupid rules like that one to argue about we would have to do something constructive. My vote goes to pulling the "cr**" out of the plane then fly on the lines you did it with, even if it is dirty kite string.
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I've been pondering......
A tuna piped IC set-up weighs around a pound (or more) when all is said and done....
I was told that an electric motor of similar power weighs 6 ounces....and a battery that is probably too much weighs 10 ounces....
Same same water buffalo....
EXCEPT that batteries are always getting lighter.
Who has the advantage?
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I've been pondering......
A tuna piped IC set-up weighs around a pound (or more) when all is said and done....
I was told that an electric motor of similar power weighs 6 ounces....and a battery that is probably too much weighs 10 ounces....
Same same water buffalo....
EXCEPT that batteries are always getting lighter.
Who has the advantage?
Yeah and don't forget the empty fuel tank weighs up to about 1 3/4 oz.
Personally I believe that on the larger competitive setups on both sides the difference is insignificant with possibly the advantage going to the electric! In fact I think I pointed that out, with the actual weights, in a previous post that received NO comments!
Plus the fact that it's easier to build an electric lighter since the vibrations loads are much lower on the fuselage!
I'm beginning to believe that we are being Conned guys! LL~ LL~ LL~
Whatever happened to common sense?
Randy Cuberly
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Whatever happened to common sense?
Randy Cuberly
[/quote]
It went out with the Obummer administration! LL~ LL~ LL~
Jerry
PS: What's common cents? HB~>
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Yup Randy...the con is on.....
Checked weights (WITH Battery v. dry IC) at the recent contest.....very close....PLUS the 6 or so ounces of fuel....I reached out to Paul Winter....his electric Yatsenkos with battery weigh what empty IC versions of the commie planes.....Have fun!
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Composite aircraft can weigh less than traditional wood /painted finishes.
Can't say I agree that building lighter aircraft is easier ; IC or electric.
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Yup Randy...the con is on.....
Checked weights (WITH Battery v. dry IC) at the recent contest.....very close....PLUS the 6 or so ounces of fuel....I reached out to Paul Winter....his electric Yatsenkos with battery weigh what empty IC versions of the commie planes.....Have fun!
I know I will regret it, but what "con" are we talking about now? There is virtually no one flying today at a competitive level that thinks Electric is at a disadvantage in any way, if anything, Electric has an advantage. Great, something works slightly better than the last thing, that's a wonderful thing. Most people are completely incapable of even evaluating it in either direction, because they can't get either one to work properly and optimally, so they are comparing the mistake they make with the mistakes someone else is making, not comparing a perfect working system to another.
No one cares, it's not important, and it's not a "con".
Brett
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Brett
My examples demonstrate that electric has NO disadvantage as far as weight...more likely, IC engines are heavier at take off.
Just sayin
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Brett
My examples demonstrate that electric has NO disadvantage as far as weight...more likely, IC engines are heavier at take off.
Just sayin
Suppose they are (in fact the current rules more-or-less guarantee that they take off with less margin over the pull test than electric - something everyone has long accepted and was designed into the rules) - who cares? What difference does that make and why is it relevant?
Brett
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The thread began with a thought that an EMERGENCY safety proposal be made....
It morphed into proposing a rule change that would compensate for the "weight advantage IC engines had over electric"....
My statement of fact is that there is no real weight advantage for IC engines.....
Just sayin
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Think over this ' PARITY ' is the word , I think .
With all the supposed ( reported ) advantages of Electric , I.C.E. need ' the Boost ' .
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The thread began with a thought that an EMERGENCY safety proposal be made....
It morphed into proposing a rule change that would compensate for the "weight advantage IC engines had over electric"....
My statement of fact is that there is no real weight advantage for IC engines.....
Just sayin
There is certainly no emergency and if you dismiss that, the rest of it is a "don't care"/"in the noise"/irrelevant. Change the weight for electric, change the weight for IC, it doesn't make any consequential competitive or safety difference either way.
And as always, you have immediately jumped to the conclusion that this is a "con", again spewing nonsensical accusations over a minor difference of opinion, and alluding to some sort of plot or conspiracy. One would have though you had learned your lesson in the 93-2005 time frame, but I guess not.
Brett
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There is certainly no emergency and if you dismiss that, the rest of it is a "don't care"/"in the noise"/irrelevant. Change the weight for electric, change the weight for IC, it doesn't make any consequential competitive or safety difference either way.
And as always, you have immediately jumped to the conclusion that this is a "con", again spewing nonsensical accusations over a minor difference of opinion, and alluding to some sort of plot or conspiracy. One would have though you had learned your lesson in the 93-2005 time frame, but I guess not.
Brett
I must take the blame (credit) for first mentioning the term "Con". I did it however as a joke indicating that the reason for the requested change was simply to provide an advantage for the "Evil" Electric Guys! it wasn't intended to be a serious challenge!
I believe this whole fact that we have required line diameters and a pull test to be just more belt and suspenders "seudo" safety regulations that have no real foundation in fact or necessity! Of course I really don't think Electric guys are "Evil"...well maybe one or two of them... and they know who they are! But I have many friends and good nice people that have gone to the dark side and still remain NICE PEOPLE! I certainly confess that I don't believe that the electric systems are better than the best IC systems but that they do have the technical advantage to become so! I don't believe they are there yet however. There is some small experimentation going on with IC engines that may level the playing field again. Experimentation with air boxes and potential fuel injection systems while expensive could easily advance IC beyond the electrics and give more consistency...potentially of course! Electrics are cheap and easy so they will have the high ground for a while. It may simply happen that there is not enough remaining energy or desire in the old crowd that has an interest in Stunt to really worry about future advancement! I would think if there are any real advances in either it will likely be from the Europeans. They seem right now to have a bit more development interest!
Right now even R/C Competition other than the stupid drones (and certainly the commercial usage for those has a determined place in the future) is highly questionable and on a big down turn!
Personally, I find disappointment in the fact that my period of greatest interest so far in stunt also comes at a time when my physical abilities due to age are also on a steep down slide! RATS! Nothing ever seems to come together...such is life! Oh well I've hopefully got a few more years wiggleing the handle even if I don't ever actually win anything!
Randy Cuberly
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This post is in reply to several comments regarding the actual weights of a full size/competitive electric model. I thought I’d add a few real world examples of my last few completed electric model weights. These models were built per the plans with no extreme measures to save weight. For example, the engine bearers were left out of the fuselage construction, but no other structural changes were made. All of the wood used to construct these models was purchased from Tom Morris. These weights include the battery and are ready to fly.
Geo-XL built in 2011: 53 ounces (5 cell battery)
Impact built in 2013: 53 -54 ounces (5 cell battery)
Impact built in 2016: 57 ounces (6 cell battery)
All of these models were finished with monokote except for the 2016 model. It has a silkspan/doped fuselage and monokote covered flying surfaces.
I shared the component weights of a typical 6 cell 60 size electric power system in an earlier post. These are actual numbers weighed on a trustworthy scale.
Please note that I don’t personally have any issue with how we are currently weighing/pull testing electric models. The purpose of this post is to simply inform the guys who have no experience with electric power systems of the true weights of a typical ready to fly electric model.
Jason
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This post in reply to several comments regarding the actual weights of a full size/competitive electric model. I thought I’d add a few real world examples of my last few completed electric model weights. These models were built per the plans with no extreme measures to save weight. For example, the engine bearers were left out of the fuselage construction, but no other structural changes were made. All of the wood used to construct these models was purchased from Tom Morris. These weights include the battery and are ready to fly.
Geo-XL built in 2011: 53 ounces (5 cell battery)
Impact built in 2013: 53 -54 ounces (5 cell battery)
Impact built in 2016: 57 ounces (6 cell battery)
All of these models were finished with monokote except for the 2016 model. It has a silkspan/doped fuselage and monokote covered flying surfaces.
I shared the component weights of a typical 6 cell 60 size electric power system in an earlier post. These are actual numbers weighed on a trustworthy scale.
Please note that I don’t personally have any issue with how we are currently weighing/pull testing electric models. The purpose of this post is to simply inform the guys who have no experience with electric power systems of the true weights of a typical ready to fly electric model.
Jason
Hi Jason,
Thanks for the post! It confirms what I basically have believed to be fact.
My Geo XL built in 2006 weighed 54 ounces with no fuel in the 4.5 ounce tank (no nitro fuel) and the wood was very carefully selected to be as light as possible. It used a Belko long shaft .56 which is a fairly light engine at 11.5 ounces with the rear exhaust muffler. It was finished in the traditional silkspan Dope finish on the entire airframe with considerable fiberglass reinforcement on the fuselage and internal areas of the engine compartment.
Had it used a typical tuned pipe arrangement on a PA65 it would have weighed significantly more. Probably as much as 6-7 ounces more plus the weight of the fuel!
It was a terrific flying airplane at that weight and perfectly matched to the power! I still miss it! It was unfortunately stolen from the flying field!
Randy Cuberly
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Offline Jim Svitko
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Re: A weighty situation
« Reply #105 on: May 03, 2018, 01:11:20 PM »
Quote
"I have also been curious about measuring the line pull in the air. With the proper equipment (instrumentation?) I suppose it could be done if someone wanted to go thru the steps. But, is it worth the time spent? Maybe, for some, but for me, it is easier to do the math. I know the weight (mass) of the plane, the radius of the circle, and with a standard lap time (5 seconds, give or take a few tenths?), I plug the numbers into the formula."
Yes, there was at least one in-situ measurement of line tension. The results were published back in probably the early 1960's. As I recall, it was done by the racing guys. They probably used load cells at the handle, or less likely, strain gages on the lines. (I remember looking at the photos and trying to decide what type of transducer was being used. I couldn't tell, other than there were electrical lead wires to some electronics strapped the pilot's belt.) They plotted the loads and compared them to the straight "centrifugal force" calculation. Their conclusion was that the actual loads were higher than the simple mass/centrifugal force calculation. I would have to find the article to see if they characterized the uncertainty of the test results. The biggest question I would have is whether they grabbed random instantaneous values or were able to collect max/max value.
A few other cautions: pilots often whip at times, which increases the line load temporarily beyond the simple centrifugal force calculation. Also, I suspect that trim can cause a significant offset in the straight and level line tension. Lots of line rake, rudder offset, engine offset, etc. These cause aerodynamic loads that are not accounted for in the simple centrifugal force calculations. Bob mentioned in one of his posts that he could show us how to reduce the excessive line tension--I liked his oil painter metaphor. I used a different one when I tried to describe motor skills and strength to guys at work: try holding a suitcase in one hand and then try to take the cap off a tube of Chapstick and apply to lips. The extra weight demolishes your fine control. Go ahead, no one is looking, try it!
Also note that increased line tension in the wind--which everyone can relate to--occurs from two sources: so-called wind-up where the plane speeds up, and also from the "crosswind drag" on the plane. Planes are not very streamlined along the lateral axis, and you can feel it. So the first one is mass related and the second is aero related.
The team race (F2C) guys experimented years ago with engine in-thrust and banana fuselages to try to reduce the in-flight drag. Not sure how much that achieved--but it made the planes a real #$@%?! to take off. Not sure anyone is still building/trimming that way. However, I know that racers trim for least out-thrust of any of the events that I have participated in. Zero everything and then push the leadouts forward until you have trouble on takeoff. Not sure how the old B-TRs in the study were trimmed, but I would start by assuming a stunter would have more aerodynamically generated line tension.
One of the other posts implied that a centrifugal force calculation wasn't valid during maneuvers. I disagree: the component of force that is solely due to the accelerating mass is always valid--if you put in the correct velocity and other inputs. However, as I tried to list above, it is only one of the vector components.
Dave