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Author Topic: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?  (Read 1101 times)

Offline Dennis Toth

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I know this will likely get some people up set but looking at rule 2.6 in the PA section it specifically seem to limit a the use of "wireless" system (not those controlled through the lines or timers onboard) used for engine shutoff to a 2.4 MHz radio. Why is this? If you only allow the shutoff system to control only irreversible engine shutoff or retracts what difference does it make as to what type of system you use to execute this? 

To me this is like setting an 85dba sound limit and saying you must use a tube type muffler when the objective is to reach 85dba.

It seems that the objective of rule 2.6 is to limit the functions of what can be controlled independent of the control lines and autonomous  onboard controls. So why does it matter how this is achivied? If the contestant has the burden of proof that should allow demonstration of any system used if asked. If someone has a simpler, cheaper idea to do an engine cutoff that doesn't use 2.4MHz radio but still only irrevserably shuts off the engine or activates the gear what difference does it make how they did it?

It seems this rule should be revised to read "Wireless..." in place of "2.4 GHz spread spectrum radio".


Best,   DennisT


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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #1 on: November 25, 2018, 08:16:07 AM »

(Clip)

It seems this rule should be revised to read "Wireless..." in place of "2.4 GHz spread spectrum radio".

Best,   DennisT

So, just what kind of "wireless" system do you have in mind?

The rule was written to prevent any other type of "wireless remote control" to be used for our CLPA models.  The rules specifically allows that the 2.4 GHz spread spectrum can only be used for the engine shutoff and/or operation of a retracting landing gear.  Rather than write the rule for what the 2.4 GHz system could not be used for, it was written to permit only these two functions.  The rule does not prevent either of these two functions to be actuated by some other on-board system or by some physical manipulation of the control lines themselves.

Keith

Offline Brett Buck

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #2 on: November 25, 2018, 08:19:08 AM »
I know this will likely get some people up set but looking at rule 2.6 in the PA section it specifically seem to limit a the use of "wireless" system (not those controlled through the lines or timers onboard) used for engine shutoff to a 2.4 MHz radio. Why is this? If you only allow the shutoff system to control only irreversible engine shutoff or retracts what difference does it make as to what type of system you use to execute this? 

To me this is like setting an 85dba sound limit and saying you must use a tube type muffler when the objective is to reach 85dba.

It seems that the objective of rule 2.6 is to limit the functions of what can be controlled independent of the control lines and autonomous  onboard controls. So why does it matter how this is achivied? If the contestant has the burden of proof that should allow demonstration of any system used if asked. If someone has a simpler, cheaper idea to do an engine cutoff that doesn't use 2.4MHz radio but still only irrevserably shuts off the engine or activates the gear what difference does it make how they did it?

It seems this rule should be revised to read "Wireless..." in place of "2.4 GHz spread spectrum radio".

  Well, you would be wrong on that one. The *only* permitted radio control function from the CL General rules is 2.4 GHz. :


2. General
A Control Line model is flown on one or more steel or GSUMP, commonly referred to as Spectra or Dyneema, lines steel wire line(s) or metal line(s) of equivalent strength, attached to the model in a manner providing aerodynamic control of the modelís elevation through manipulation of the control surfaces during flight. Movement of control surfaces, and any other of the modelís operational features, may be accomplished by mechanical means, by electrical impulses transmitted through the line(s), or by any other control system that does not interfere with the control of any other model or present a safety hazard to competitors or spectators. The use of radio control to accomplish any control functions on Control Line models is specifically prohibited except as follows. The use of 2.4 GHz (utilizing spread spectrum, 47 CFR Part 15) radio control to accomplish functions other than providing aerodynamic control of the modelís elevation on Control Line models is allowed, but only to the extent and in the manner specifically allowed by the rules of the individual event. All control functions must be under the direct control of the pilot and only the pilot.


This rule existed before the stunt rule. The stunt rule (which I wrote at the behest of someone else) limited the one available radio control method to the functions we discussed for purposes of stunt. The alternative was to make all radio control including 2.4GHz completely illegal for CL Aerobatics, which I might still propose.

    The general rule (which I more or less agree with) defines CL models as models controlled through the lines, with minimal/trivial use of radio. I could support (and did in the past for FAI) defining control line as using "control via the lines", which excludes radio or other parts of the EM spectrum as a transmission medium entirely. If people want to use radio control, there is a very large rule book for that.

   The intent when it was proposed for FAI was to remove the possibility of control external to the pilot in flight, like the "back rooms" used for Formula 1 races, where the car is continually monitored and adjusted during the race with the team at the site not even being aware of most of it. Of course we aren't going to have it on that scale, but lots of people would really like to have EGT telemetry and then adjust the compression screw on their TR model to keep it from burning down, and you could easily do live needle or throttle tweaks on a stunt plane (including ground-based  control loops) for any number of functions.

    You may consider that absurd, but think what people like Igor or Howard (or even worse, Brett) could do if they weren't limited to making their control algorithms fit in the teeny on-board processor. Given that the transport delay could be milliseconds, you could do almost anything.
 
   The permitted functions were intentionally chosen to be trivial with minimal impact on the performance (although you could argue that the retracts matter a little bit - but I am not sure whether it helps or hurts to clean up the parasitic drag) so that 2.4 GHz. does not become mandatory to remain competitive.

   Brett

p.s.     As an aside, note that this also refers to "GSUMP" which is not a defined term by anyone (it stands for Gel Spun (ultra-high) Molecular (weight) Polyethylene), and specific brand names, both of which should be removed, since they are undefined. I don't think we should be using "enthusiast" or proprietary terms for a what amounts to a specification document. Since no one seems very close to writing a sensible rule for Stunt use of plastic lines, I don't see a big rush to change the General rule.

On the topic of retracts, it would probably help on the electric and hurt on IC. On electric, cleaning up the drag would give you more margin on the power for a given weight, which would permit you to use the energy thus saved in a more useful way, like less pitch and more RPM, to get permit a less efficient prop.
   

Offline bob whitney

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #3 on: November 25, 2018, 08:28:42 AM »
 Z@@ZZZ this is a no Brain er,  before 2.4 they had 2 sets of frequency's, one for ground and water and the other for air . so they wouldn't interfear with each other .AMA clubs had a frequency board and when you got ready to fly u removed the clip with your frequency you were using on it .it was hard to control if two diff groups were flying close to each other  another problem was someone in the pits checking out there plane on the same frequency u were flying on, instant crash. 2.4 is almost mandatory in all sanctioned RC car and plane competitions . how would u feel if u were in the middle of a maneuver and some one turns on their transmitter and shuts off your engine???
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Offline Dennis Toth

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #4 on: November 25, 2018, 09:08:40 AM »
The type other than 2.4MHz could be a simple car key-fob, might be a light beam, sound pulse,  or other similar devise. Just seems that we want to limit the operations it can control not the means of activation. 

I understand that if using radio, from an interference point the 2.4 is superior to any other radio frequency. But that is the pilots problem if they choose to use something else.

I still didn't read any specific reason why we allow only 2.4MHz type radio when a wireless system is employed. I agree with the limits on the "what" can be controlled this way just not the how.


Best,    DennisT

Offline Tim Wescott

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #5 on: November 25, 2018, 02:27:55 PM »
2.4GHz spread spectrum because that's what's known to work without requiring a transmitter impound area at a CL meet.  Yes, there's a lot of other ways to skin this particular cat, but 2.4GHz spread spectrum systems are known to work, and don't require CDs to either be radio engineers or lawyers.

Give the number and variety of good cheap 2.4GHz RC systems out there, I don't think it's too onerous to allow only them.
« Last Edit: November 25, 2018, 03:49:21 PM by Tim Wescott »
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Offline Brett Buck

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #6 on: November 25, 2018, 03:41:41 PM »
2.4GHz spread spectrum because that's what's known to work without requiring a transmitter impound area at a CL meet.  Yes, there's a lot of other ways to skin this particular cat, but 2.4GHz spread spectrum systems are known to work, and don't require CDs to either be radio engineers or lawyers.

Give the number and variety of good cheap 2.4GHz RC systems out there, I don't think it's too onerous to require them.

  Well, to be entirely accurate, they aren't required at all. The stated allowable uses aren't worth doing for the most part and certainly not necessary, which was intentional.

     Brett

Offline Tim Wescott

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #7 on: November 25, 2018, 03:49:34 PM »
  Well, to be entirely accurate, they aren't required at all. The stated allowable uses aren't worth doing for the most part and certainly not necessary, which was intentional.

     Brett

Post edited for clarity.
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Offline Dennis Toth

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #8 on: November 25, 2018, 04:24:31 PM »
I understand that 2.4MHz is available and reliable and doesn't require impound. All well and good but since the allowable control functions are not life threatening. The rules should not be there to protect one from bad decision. The rules lays out what can and cannot be done, not how you chose to achieve that end. 

What is the specific concern with having other wireless types of actuation as long as they only activate an irreversible engine shutoff and/or operation of a retracting landing gear? It is just irrelevant as to what carries out the function as long as the function is what is prescribed in the rules. Why shouldn't be revised?

Best,    DennisT

Offline Brett Buck

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #9 on: November 25, 2018, 04:58:58 PM »
I understand that 2.4MHz is available and reliable and doesn't require impound. All well and good but since the allowable control functions are not life threatening. The rules should not be there to protect one from bad decision. The rules lays out what can and cannot be done, not how you chose to achieve that end. 

What is the specific concern with having other wireless types of actuation as long as they only activate an irreversible engine shutoff and/or operation of a retracting landing gear? It is just irrelevant as to what carries out the function as long as the function is what is prescribed in the rules. Why shouldn't be revised?

   So, you are debating the rule from CL General that defines CL models as only permitting 2.4 GHz and nothing else, rather than stunt? Because to change that, you have to make sure there are no conflicts with any other rules or any other events that permit it, not just stunt. Note that before the rule you mentioned in stunt, the CL General rule had the effect of *completely outlawing any form of remote control*, because, when it was added, stunt had not put in any rules at all about it. Adding this rule permitted it again, but only for the functions mentioned.

   Before the CL General rule was passed, it was a gray area, and everyone had erred on the side of permitting literally anything, including Antonio Zigras' ZTron IR system.

    To change it the way you want, you will have to change the CL General rule, along with the stunt rule, which I predict will prove extremely difficult. But it for sure won't happen if you don't try. That will give you two years, before someone removes the current stunt rule and outlaws all forms of remote control.

    Brett

Offline Dennis Toth

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #10 on: November 25, 2018, 05:30:37 PM »
Why not just change the stunt rule to allow wireless control of only the functions already in the stunt rule?

What was wrong with the use of the ZTron IR system, again, if it only controlled the functions defined in the rules?

Best,    DennisT

Offline Brett Buck

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #11 on: November 25, 2018, 05:52:51 PM »
Why not just change the stunt rule to allow wireless control of only the functions already in the stunt rule?

  Because then the stunt rule would be in conflict with the rule in CL General! This is not hard or tricky, we can't allow something that the general rule explicitly prohibits.

   The "2.4 GHz only" comes from the "General" section, not the stunt rules. I just wrote the rule to be compatible with the (already existing) CL General rule.

     I will make an anonymous "I Told You So!" to the person who requested I add the rule in question. My original inclination was to prohibit ALL forms of remote control for ANY function,  since it is not consistent with the definition of "control line". 

      Brett

   

Offline Dennis Toth

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #12 on: November 25, 2018, 06:22:31 PM »
OK, I see were the 2.4MHz comes from in the General Rule, sec 2. Since this covers more than just CL stunt it might be a bit more complicated to get the wording to cover other events. Anyway now I understand and can think about it a little more.

Best,   DennisT

Offline Dan Berry

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #13 on: November 25, 2018, 08:10:22 PM »
https://airtekee.wordpress.com/rdt/

Why wouldn't this be allowed to move a servo and kill the engine?

Offline Ken Culbertson

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #14 on: November 25, 2018, 11:29:30 PM »
Timers have all but eliminated overruns in electric power.  I had two last season using IC, one cost me a "trophy".  I spent years learning how to measure fuel, change the nitro, tweak needle valves, change plugs and use the proper profanity all to get our little show to fit in the 8 minutes we are allotted to dazzle the judges.

That is one part of the sport I will actually miss moving to electric.  I can understand IC wanting to have the same edge that electric now has in this area BUT, the rules are the rules.  You can either build and fly under them or work to change them.

Every time we go out to get an edge it soon becomes difficult to win without it and those that need an edge start looking for a new one.  What this does is gradually increase the cost in $$$ and time just to be competitive. My recommendation if you can't get down under 8 min is to use less fuel and learn when you need to.

Ken
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Offline Lauri Malila

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #15 on: November 25, 2018, 11:39:11 PM »
https://airtekee.wordpress.com/rdt/

Why wouldn't this be allowed to move a servo and kill the engine?

I use it. Ken made me a special version of stand alone rdt that I use to squeeze fuel line. Works well. I don't care about it in contests but it's an excellent aid in testing and trimming.

This discussion is another example of how you should not base any rules to an existing technology. Same with Dyneema, copper wire wrapping, 2,4GHz.. L

Offline Brett Buck

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #16 on: November 25, 2018, 11:54:17 PM »

Every time we go out to get an edge it soon becomes difficult to win without it and those that need an edge start looking for a new one.  What this does is gradually increase the cost in $$$ and time just to be competitive. My recommendation if you can't get down under 8 min is to use less fuel and learn when you need to.

   That's an interesting observation, but since we have had more advanced systems, the cost and time seem to have gone down. You could easily and safely get by with a single PA or RO-Jett engine (I only had 1 PA61 for the entire time I ran it). And the amount of time you have to spend practicing has gone down drastically, it's a tiny fraction of the time.

    What dominates my cost and time is travel, even a weekend trip costs upwards of $400-500, and getting back and forth to Muncie is 6 full days just for the driving, plus gas and hotels along the way.

      Brett

Offline Chuck_Smith

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #17 on: November 26, 2018, 04:40:49 AM »
As mentioned, no impound is required. I'd sure as heck not like having to wait for a frequency pin to fly, much less the logistics effects of a contest.

I can't speak for the rest of you, but if my engine shuts off unexpectedly it can be catastrophic. Given the cheap price of a receiver, a 2s and a servo these days I doubt I could build anything better myself for twice the price.

Chuck
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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #18 on: November 26, 2018, 04:50:34 AM »
https://airtekee.wordpress.com/rdt/

Why wouldn't this be allowed to move a servo and kill the engine?

$300 is kind of steep.
You can do the same thing with 2.4 for way less than that.
Some of us in the Mi/Ont combat group have been using an electronic system for F2D for several years now.
Airborne unit is <$30. Transmitter (that fits in a pill bottle) <$60
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Offline Ken Culbertson

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #19 on: November 26, 2018, 06:56:50 AM »
   That's an interesting observation, but since we have had more advanced systems, the cost and time seem to have gone down. You could easily and safely get by with a single PA or RO-Jett engine (I only had 1 PA61 for the entire time I ran it). And the amount of time you have to spend practicing has gone down drastically, it's a tiny fraction of the time.

    What dominates my cost and time is travel, even a weekend trip costs upwards of $400-500, and getting back and forth to Muncie is 6 full days just for the driving, plus gas and hotels along the way.

      Brett
What you are referring to is improvements in existing technology for which I 100% agree and Amen to the travel.  That is probably the largest problem we face.  What I was referring to, and probably did not explain properly, is when a new technology or gizmo becomes the norm.

I was shocked at the cost of the "state of the art" piped engines when I came back from the wilderness but I was told I needed one to be competitive.  Probably true.  I could afford the LA46 size ship, which was a doubling of power compared to what I knew, but the performance of the piped ships in the hands of the better fliers is simply out of reach.  I am not a big fan of flying other peoples planes so I have not had the opportunity to fly one.  That is probably a mistake and I may relax that a bit if asked to try it but I will never be the one to ask.

I am still perplexed why we are constantly trying to eliminate the non-flying skills we use to have to acquire to win but it is not my turn any longer to define the sport.

Ken
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Offline Paul Smith

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #20 on: November 26, 2018, 07:40:06 AM »
You could use a 27 or 52 or 72 to shut off your engine and nobody would know or care.

Since I'm not an old time RC'er, I just buy 2.4 three-channel car controllers for $30 and receivers for $4.
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Offline Brett Buck

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #21 on: November 26, 2018, 10:09:11 AM »
What you are referring to is improvements in existing technology for which I 100% agree and Amen to the travel.  That is probably the largest problem we face.  What I was referring to, and probably did not explain properly, is when a new technology or gizmo becomes the norm.

I was shocked at the cost of the "state of the art" piped engines when I came back from the wilderness but I was told I needed one to be competitive.  Probably true.  I could afford the LA46 size ship, which was a doubling of power compared to what I knew, but the performance of the piped ships in the hands of the better fliers is simply out of reach.  I am not a big fan of flying other peoples planes so I have not had the opportunity to fly one.  That is probably a mistake and I may relax that a bit if asked to try it but I will never be the one to ask.

I am still perplexed why we are constantly trying to eliminate the non-flying skills we use to have to acquire to win but it is not my turn any longer to define the sport.

    I am not sure what the last bit is about, I don't see very many people trying to do that, if anything, we are continually fighting to keep it more-or-less the same way. The stunt rule in question was intentionally crafted to make the entire idea fall into the "neat, but more-or-less useless" category. I would probably support a proposal to eliminate ALL RC means in control line, and I have been surprised that no one has made any effort to eliminate on-board feedback control of the aerodynamic controls. I am OK with it on the engine/motor, because all Igor's system does is even up the odds between electric and IC, where such feedback control has long been part of the event, back to the 4-2 break.

     I know I have spent less in "constant" dollars on equipment like engines/pipes/props than I used to, and it has the added advantage of having some notion that it will work when you need it to. The biggest waste of time and money I can imagine is spending $500 going to a weekend two-day contest, and then having your engine not run properly, or only once in a while, and also having everyone else in the same boat, generating random results. If anything, current systems *save* money and time on wasted activity. Fuel was relatively expensive in the good old days, and you burned it like it came from a tap, with the competitive fliers taking a thousand or more flights a year- which at ST46 rates, it something like 50 gallons a year.

   I wouldn't deny, however, that modern equipment and techniques have changed the nature of the competition. Many more people are able to be competitive than they were before, because the former winning approach of the black art of making engines work and the extreme amount of effort and practice required to learn how to work around performance limitations made it so only a few people who adopt stunt as a way of life could possibly compete. Now, you can just buy a system, and if you follow the directions* you are going to have something with so much performance margin, all you have to do is stand there and fly it around. That only happened on rare special moments back in the "Good Old Days", and on those days, whoever managed it usually won. That makes it so almost anyone can do it, as long as they approach it logically and rationally.

     I might also suggest, gently, that you might be jumping to conclusions about the nature of current competition. I am not sure who you are flying with on a regular basis, and which big contests you have attended and been deeply engaged in, to be able to see what is really going on and what the likely winners are actually doing. If you haven't had those types of exepriences, I would ask you to reserve judgement.

    Precisely because of the widespread availability of "overkill" power and trim knowledge, many people can be *very good* stunt fliers without actually knowing much about what they are doing, whereas before, you had to master a huge array of things even to be reasonably good. These guys fly better than their equivalents from ancient times - but they have the same chance against David and Paul that their counterparts did against McFarland and Gialdini- that is, *no chance at all*.

     Brett


*note that a large number of people still fail to or refuse to follow the directions, and *still* shoot themselves in the foot, the "engine setup tips" forum being a case in point. Its' like going back in time to 1975.

Offline Tim Wescott

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #22 on: November 26, 2018, 11:11:40 AM »
    Precisely because of the widespread availability of "overkill" power and trim knowledge, many people can be *very good* stunt fliers without actually knowing much about what they are doing...

That would be me.  Or at least, I'm pretty good (Expert, but not top 20 day good), and I can feel profoundly ignorant sometimes.
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Offline Ken Culbertson

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #23 on: November 26, 2018, 01:22:27 PM »
    I am not sure what the last bit is about, I don't see very many people trying to do that, if anything, we are continually fighting to keep it more-or-less the same way. The stunt rule in question was intentionally crafted to make the entire idea fall into the "neat, but more-or-less useless" category. I would probably support a proposal to eliminate ALL RC means in control line, and I have been surprised that no one has made any effort to eliminate on-board feedback control of the aerodynamic controls. I am OK with it on the engine/motor, because all Igor's system does is even up the odds between electric and IC, where such feedback control has long been part of the event, back to the 4-2 break.

     I know I have spent less in "constant" dollars on equipment like engines/pipes/props than I used to, and it has the added advantage of having some notion that it will work when you need it to. The biggest waste of time and money I can imagine is spending $500 going to a weekend two-day contest, and then having your engine not run properly, or only once in a while, and also having everyone else in the same boat, generating random results. If anything, current systems *save* money and time on wasted activity. Fuel was relatively expensive in the good old days, and you burned it like it came from a tap, with the competitive fliers taking a thousand or more flights a year- which at ST46 rates, it something like 50 gallons a year.

   I wouldn't deny, however, that modern equipment and techniques have changed the nature of the competition. Many more people are able to be competitive than they were before, because the former winning approach of the black art of making engines work and the extreme amount of effort and practice required to learn how to work around performance limitations made it so only a few people who adopt stunt as a way of life could possibly compete. Now, you can just buy a system, and if you follow the directions* you are going to have something with so much performance margin, all you have to do is stand there and fly it around. That only happened on rare special moments back in the "Good Old Days", and on those days, whoever managed it usually won. That makes it so almost anyone can do it, as long as they approach it logically and rationally.

     I might also suggest, gently, that you might be jumping to conclusions about the nature of current competition. I am not sure who you are flying with on a regular basis, and which big contests you have attended and been deeply engaged in, to be able to see what is really going on and what the likely winners are actually doing. If you haven't had those types of exepriences, I would ask you to reserve judgement.

    Precisely because of the widespread availability of "overkill" power and trim knowledge, many people can be *very good* stunt fliers without actually knowing much about what they are doing, whereas before, you had to master a huge array of things even to be reasonably good. These guys fly better than their equivalents from ancient times - but they have the same chance against David and Paul that their counterparts did against McFarland and Gialdini- that is, *no chance at all*.

     Brett


*note that a large number of people still fail to or refuse to follow the directions, and *still* shoot themselves in the foot, the "engine setup tips" forum being a case in point. Its' like going back in time to 1975.
Brett:
I think we are talking past each other.  I do not disagree with anything in your last post which means I was not clear in mine.  The 2.4 rules are perfectly fine as is.  If you want an engine cutoff or retracts for an IC plane you have a way to do it.  If you want to go electric, both are built in.  I do not have the luxury of going to any of the larger meets anymore mainly for the travel $$$ that you have clearly identified as the biggest problem we have. I do follow who wins and what they were flying.   Names you would recognize that I fly locally with now include Mike Scott, Phillip Nichols and on occasion one or both of the Moon brothers.  My best years were 1975-81.  I don't remember us having all of those engine problems but then the crowd I flew with then knew what they were doing.  I see just as many bad runs with the new engines as I did back then but my experience may not be typical.  All I had for competition were two 35's; a Fox that I got from Duke at the '64 NATS and an OS that came from "Big Art" around '76.  I still run the OS.

One thing that is clear from following all of this is that a lot of people don't bother reading the General Rules.

Ken

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Offline phil c

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #24 on: January 25, 2019, 02:34:01 PM »
OK, I see were the 2.4MHz comes from in the General Rule, sec 2. Since this covers more than just CL stunt it might be a bit more complicated to get the wording to cover other events. Anyway now I understand and can think about it a little more.

Best,   DennisT

The bottom line Dennis is that spread spectrum 2.4GHz radio is pretty much immune to interference.  That means some cannot accidentally or on purpose shut off the engine or do something else to interrupt the flight.  There's also no need to impound transmitters for frequency control.  It's also unlikely the government will change the radio frequency it is only a tiny sliver of the radio spectrum.  It will never interfere with any other uses except possibly some esoteric science experiment.
phil Cartier

Offline Lauri Malila

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #25 on: January 25, 2019, 02:59:11 PM »
So is the beforementioned Airtek RDT-unit pretty much immune to interference.
As I said before, the rule should simply allow or not the use of wireless shut-off, without going to details.
If it fails to work well, it's pilots problem and lines take care of safety of others. L

Offline Fredvon4

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #26 on: January 26, 2019, 12:38:55 PM »
ASKED>>>>>>>Airtek RDT-unit pretty much immune to interference??

yes and no....but moot as it is NOT spread spectrum 2.4Ghz   thus illegal to use in competition....fine for sport use

That said, the Airtek RDT 800~990 Mhz frequencies and low power ----make it basically immune to interference at a typical flying site

Unless deployed in a neighbor hood with a lot of Baby monitors or other consumer electronics in those  frequency ranges...Senheiser Wireless head phones as another example

As noted above; the Airtek RDT is way over priced for that function...

I have a very good similar system custom built for $100

As noted above any cheap RC car Trans ($18~$35) and very very cheap $4~$6 orange receiver...one or two 5 or 9 gram servos are under $10....and low density adaquat bats can also be had under $10....I can easily build a fuel cut system from on hand items in my shop for under $45
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Offline Lauri Malila

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #27 on: January 31, 2019, 03:42:32 PM »
ASKED>>>>>>>Airtek RDT-unit pretty much immune to interference??

yes and no....but moot as it is NOT spread spectrum 2.4Ghz   thus illegal to use in competition....fine for sport use

That said, the Airtek RDT 800~990 Mhz frequencies and low power ----make it basically immune to interference at a typical flying site

Unless deployed in a neighbor hood with a lot of Baby monitors or other consumer electronics in those  frequency ranges...Senheiser Wireless head phones as another example

As noted above; the Airtek RDT is way over priced for that function...

I have a very good similar system custom built for $100

As noted above any cheap RC car Trans ($18~$35) and very very cheap $4~$6 orange receiver...one or two 5 or 9 gram servos are under $10....and low density adaquat bats can also be had under $10....I can easily build a fuel cut system from on hand items in my shop for under $45

Well, I have propably used the Airtek unit more than anyone in this forum. I have about a dozen of them and they have a flawless track record over last 15 years I've had them, that is over 10000 flights, easily.
I've only had 2 or 3 unwanted DT's or cases when DT failed to work but that was long ago and all of them in extreme cold/wet weather, then we quickly learned to protect the electronics from weather elements.
Of course, that's in free flight but during the couple of years I've had the shut-off system based on it in stunt, it has also worked flawlessly. Reliability of these systems depends more on the mechanical parts.
I'm sorry that I stick my nose to this, it's not my business. I'm just curious to know why the wording in your rule is what it is.
And I repeat (maybe 3rd time) again, this kind of rules should never be based on some spesific technology. 2,4ghz is handy now, some time ago it was PCM, before that FM or AM. What comes next?
While not absolutely necessary in contest use, remote shut-off also improves safety and partially also levels the playground when flying against electrics. And in case of a bad engine run, it's a nice gesture to others to eliminate unwanted noise and waiting. L

Offline Brett Buck

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #28 on: January 31, 2019, 08:09:26 PM »
I'm sorry that I stick my nose to this, it's not my business. I'm just curious to know why the wording in your rule is what it is.
And I repeat (maybe 3rd time) again, this kind of rules should never be based on some spesific technology.

   The CL General rule came about to eliminate the need to have frequency-control at control line contests, and to eliminate any issues with attempted or claimed jamming, which (rightly or not) 2.4 GHz. seems to preclude. The General rule removes all the other options.

   The CL Stunt rule came about after 2.4 GHz was already the only option. In that rule (which I wrote and proposed), the only options I seriously considered were:

 
  • Secondary functions that do not affect performance enough to make them a de facto requirement
  • not permitted at all.

    I was leaning heavily towards banning RC completely, given that there are a 100+ RC events already. I know a lot of people think the same. I did eventually propose only retracts and engine shut-off, because neither of those will make any significant difference in the performance.

     Banning it completely certainly solves the problem of choosing specific technology, it eliminates any form or wireless communication at all, which is pretty solidly defensible since "control line" actually literally means control through the lines.

    If anyone thinks otherwise, then, nothing is stopping them from proposing whatever they want, including changing the CL general rule. I predict that will fail due to lack of support, but, it sure won't happen if it is never proposed.

    Brett
   
 

   

Offline Ken Culbertson

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Re: Why is "only" a 2.4 MHz wireless system allowed for engine shutoff?
« Reply #29 on: January 31, 2019, 08:57:57 PM »
   
 
  • Secondary functions that do not affect performance enough to make them a de facto requirement

 

Thank You - I was concerned where we were headed when the "Ultra Scale" planes started becoming popular.  Fortunately they did not dominate and you can still win with classical designs and if you have the time and resources to go that route, good for you but you don't have to go that route to win.  Of all the things RC could do for us, I only think that a fuel shutoff is a good thing.  Even retracts don't do as much as you would expect for performance and they really complicate things.  Nothing wrong with that rule

ken

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Offline IdRatherBeBuilding

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I'm new to CL but I do see the argument about 2.4 exclusively. 2.4 is good, especially for CL which always has a line of sight and is only 60' max distance. But there are lots of other systems just as good, and more keep popping up.

I wouldn't think banning wireless completely would be an answer for this debate. That wouldn't seem to serve a progressive movement in the hobby. Which is what we want right. I mean, that would be the whole reason for even allowing wireless in the first place.

As far as being able to cheat. Transmitters have wireless trainer systems now. So it would be possible to cheat with the way the rules are now. On 2.4ghz.

Accidental tx power ups happen on 72mhz. Like All the time. Impounding isn't too frustrating, but it is one more thing to deal with. That time and energy could be spent elsewhere to create a more pleasant experience for all. I get that Completely.. More than I'd like yo actually.
A simple answer is to ban 72, 75, 27 and 53 mhz systems from contests.

I actually was considering doing a plane up with wireless controls. I have about 30 plus RC systems from tubes to futaba 14mz. But my first choice for CL would be using my phone on bluetooth with an arduino rec. in place of a timer for my esc on electrics. I just figured it would be easier to touch my screen and go.

David
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