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General control line discussion => Open Forum => Topic started by: Tim Wescott on May 16, 2012, 03:44:30 PM
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I don't know if I'm the only one that this has happened to, but I just had my 3rd or 4th crash for the same reason -- so I'm making a change.
The picture shows what happened: I'm using a Fancher-style hard point handle, with various lengths of line clips to tune the airplane response. In the square maneuvers, once in a great while, one line gets hooked in the clip for the other, and the plane starts looping. The first time that I know this happened I had to do a total rebuild on the plane (and heal up from minor cuts on my hand -- don't grab your lines when you have a control problem); the second time I did a high-speed inverted landing on the pavement at Delta Park (this was my Friday evening crash at the Spring Tuneup). Both of those times there were other things going on, and I blamed exceptional circumstances on the lines getting hooked.
Today, with absolutely nothing weird going on, I had it happen again. Fortunately I was able to do the "step in, step back" thing and bring it down with nothing worse than a broken prop -- but I'm getting tired of this!
When this happened to me at the contest I went over my handle design and my clip handling with Richard Entwistle, who uses the same method of line attachment: he reported no problems.
So, I don't know what I'm doing differently than all the folks who have used this method with great success, but from now on I'm putting the adjustment clips at the leadouts, and I'm using these at the handle:
http://brodak.com/control-line-parts/control-line-connectors/control-line-connector-extra-large-35-and-up.html
If anyone has suggestions about why this problem may be striking me and no one else, I'm all ears.
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take a 1" length of fuel tubing and push it onto your lines - when you clip your line to the clips - slide the tube over where they meet - problem solved
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take a 1" length of fuel tubing and push it onto your lines - when you clip your line to the clips - slide the tube over where they meet - problem solved
I was trying to figure out how to do that with heat-shrink tubing: your way sounds like it'll actually work.
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I use more like 3", and of 1/4"-OD rubber tubing. It's standard combat practice. I'll give you some if I go to Eugene.
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Make the terminations cleaner, no crimps with "tags" hanging out. Instead, wrap them and cover the wrap with heat shrink. Howard method on top of that is also a good idea. I see people getting away with "dirty crimps" all the time but it is just one more thing for Murphy to interfer with.
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I've had this happen on that set of crimped lines, but today's was on a nice, new set of lines with a tidy and neat wrapping job (albeit one without the heatshrink).
Howard, what do you mean if you come to Eugene?
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These are also available from Brodak and are much more secure than those with the metal wrap in the middle, which are longer and can pull apart. The price quoted is for a pair of clips.
http://brodak.com/control-line-parts/snap-connectors/110-lb-test-snap-connector.html
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Tim,
I propose again that you watch other experienced pilots,, I think perhaps you have your controls set up to numb,, ( requiring to much wrist motion) or that you are "yanking" for the squares. Perhaps even you maybe not following the plane with your handle , but I dont see with your setup, how you should be getting the lines close enough to the clips to actually snag,,
that said, I have seen the fuel tubing used effectivly,,
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Tim,
I propose again that you watch other experienced pilots,, I think perhaps you have your controls set up to numb,, ( requiring to much wrist motion) or that you are "yanking" for the squares. Perhaps even you maybe not following the plane with your handle , but I dont see with your setup, how you should be getting the lines close enough to the clips to actually snag,,
that said, I have seen the fuel tubing used effectivly,,
Yep, 100% correct!
Derek
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, but I dont see with your setup, how you should be getting the lines close enough to the clips to actually snag,,
that said, I have seen the fuel tubing used effectively
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Has happened to me at the third loop of the clover there was so much slack I used all the up I could and got tangled up like that. After that I bought the X-tra large fuel tubing works for me too. But I also try to be in the right spot to do the clover from now on HB~>
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This might be a root cause - twist in each individual line. Take the handle off the lines, then walk out the lines from the airplane to the handle end. if there are twists in the individual lines this will eliminate them.
Then do the fuel tubing trick too.
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If you slowed the control system at the bellcrank/control horns, you wouldn't need to run the line spacing at the handle so narrow that they catch on each other.
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Tim,
I propose again that you watch other experienced pilots,, I think perhaps you have your controls set up to numb,, ( requiring to much wrist motion) or that you are "yanking" for the squares. Perhaps even you maybe not following the plane with your handle , but I dont see with your setup, how you should be getting the lines close enough to the clips to actually snag,,
that said, I have seen the fuel tubing used effectivly,,
This might be a root cause - twist in each individual line. Take the handle off the lines, then walk out the lines from the airplane to the handle end. if there are twists in the individual lines this will eliminate them.
Then do the fuel tubing trick too.
I don't do it every time, but probably once every third or fourth time I hook up I make sure that the individual lines aren't twisted.
I don't think that I'm yanking on the lines -- but I'm not comfortable enough yet in the pattern to pay attention to such nuances. (Come to think of it, crash #1 involved the plane going slack on the lines and coming back tangled -- but I know that crashes #2 and #3 both happened with good line tension).
I think I'm going to do the fuel tubing or sleeve-type clevis thing, and see if I can pay attention to whether I'm really yanking things around. I don't want to try solutions without having some real guaranteed fix in place -- I don't have enough props for that, much less enough airplanes.
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If you slowed the control system at the bellcrank/control horns, you wouldn't need to run the line spacing at the handle so narrow that they catch on each other.
That's a good thought for the next plane.
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I've never had this occur..
I would suspect your jerking the lines - its the onyl way you can certainly be having them go slack and bind / snag.
I also put heat shrink over that section - to make it smoother.
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I guess I'm surprised others havent mentioned it directly but I think you are rotating your handle beyond the rotation of the bellcrank and generating a slack line. I would do what Howard suggested and work on limiting your control and handle throw. Maybe the plane is nose heavy and your pulling to hard to get the plane to corner. If the thing drops and doesn't glide well when the engine quits it may be nose heavy.
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They actually make a liquid black wire insulation you paint on with the included dobber. But the fuel hose works pretty good too.
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Your line clips look entirely too long to me; and are they strong enough? They look like paper clips. Having a bazillion holes for fine neutral adjustment - is it really necessary? Half the holes, larger holes, could allow a more substantial line clip, with adequate adjustment.
What diameter of flight lines are you using? The photo may be fooling me, but they look thin. Your terminations can be cleaned up - the use of shrink tubing over them is definitely a good idea. Even if those ends somehow overlap or touch, there shouldn't be any parts to catch on each other.
BTW, your handle has a fine grip and finish.
No more crashes due to the problem you describe!
Best,
L.
"Never let the fear of striking out get in your way." -Babe Ruth
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Tim , i had this happen last year on a windy day and got slack lines,busted my Barnstormer in half. Now i use 1/8 or 3/16 shrink tubing , down side black , up side red, both ends when making up lines. So far , so good. Good luck.
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Peter, PJ, Ray, et all:
I know that crash #1 involved the lines going slack, and thinking about yesterday (gusty wind) I think that could be the cause of crash #3 as well. The contributing cause of crash #2 was a severely nose-heavy plane: hanging on the up- or down-line, the thing would do a loop whose diameter projected out to about a 30 degree height, and at the time of the crash I was purposely giving it tons of input to verify that yes, I really did need to make a balance change and not a handle change.
Larry:
It's a 34 ounce plane and those clips have been pull tested. The line is 015, which is one step larger than the required 012 from the rule book. I can't remember the exact pull strengths, but the clips don't severely distort until I'm over the 21 pound pull for the whole plane, on one clip, and they don't distort permanently until I'm up around 50 pounds or so -- and even then, the permanently distorted clip carries the weight OK, it just looks Really Bad. I haven't had a flight -- even with some go-slack-and-bang events -- that has permanently distorted a clip, so I feel quite safe using them.
And, as I've mentioned elsewhere in this thread, I've had this trouble happen on lines with much nicer terminations. It is not the terminations that are catching -- it is the line itself that is getting caught up in the clip. So while I'm not going to build another set of lines with terminations that ugly, I don't think that's the problem in this case.
Peter:
If anything, the plane in its current trim is a bit tail-heavy (crash #3) -- but crash #2 certainly seemed to be brought on by a combination of nose-heavy and my ham-fisted diagnostic procedures.
I think that -- being a beginner -- I must be jerking on the lines when things get "interesting". I suspect that will go away with time, but in the near-term I think that some sort of anti-snag protection on the line clips itself is what I need to do: once I get better I can maybe toss them, but until that day I just need training wheels.
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Tim
Everyone has given you great info...all very applicable.
Noting, you are here in the northwest area, yesterday was very windy here in Salem ( yes I was out in the late PM tuning a new one). I'm a retread, but with fair handle time....I experience much the same thing when I'm doing Squares. Two very experienced flyer's have observed that my hand is jerking up to much and to hard.
Try rotating your wrist slightly, just before you "pull" for the square, may give a smoother application of control. I'm sure there are many ways to solve your problem....Good luck
Dave.
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Tim
Everyone has given you great info...all very applicable.
Noting, you are here in the northwest area, yesterday was very windy here in Salem ( yes I was out in the late PM tuning a new one). I'm a retread, but with fair handle time....I experience much the same thing when I'm doing Squares. Two very experienced flyer's have observed that my hand is jerking up to much and to hard.
Try rotating your wrist slightly, just before you "pull" for the square, may give a smoother application of control. I'm sure there are many ways to solve your problem....Good luck
Yup -- windy, and rolling over trees on its way to my flying circle.
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As mentioned earlier, or at least asked about, that handle and the line spacing being used is what we call a clue. With any model such as this within reasonable parameters your line spacing at the handle, and continuing "It won't turn!" comments pretty much nails it: You simply don't have much output at the 'crank.
As it can't get better, whack into the thing and move output to elevator pushrod away from the--never mind, you're a smart boy and I needn't describe required mods.
Shoulda left that factory-supplied hatch in operation instead of plastering it over!
Test flights can be made by simply covering your new access hatch with tape. Finish it nicely later.
Dan
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As mentioned earlier, or at least asked about, that handle and the line spacing being used is what we call a clue. With any model such as this within reasonable parameters your line spacing at the handle, and continuing "It won't turn!" comments pretty much nails it: You simply don't have much output at the 'crank.
That handle is for my SkyRay, used for illustration purposes only -- the spacing at the handle for the Streak is (currently) much narrower.
Besides, the stop-stop elevator travel on the thing is +/- 40 or 45 degrees -- I would assume that more than that will just give me a drag brake.
As it can't get better, whack into the thing and move output to elevator pushrod away from the--never mind, you're a smart boy and I needn't describe required mods.
Thus giving me more than +/- 45 degrees of elevator travel?!?!
Shoulda left that factory-supplied hatch in operation instead of plastering it over!
Test flights can be made by simply covering your new access hatch with tape. Finish it nicely later.
Nope, Mark or a previous owner glued it shut: I lovingly restored it to original factory condition, complete with two shiny stainless steel screws. (I didn't grow up reading Street Rodder magazine for nothin' -- the plane also has parts on it that are Hand Machined from Solid Billet, thereby making it cool).
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Sorry, I'm definitely not suggesting more travel - you've got plenty of that. What I am strongly suggesting is the rate of travel is whacked.
And the actual Flite Streak handle has an even narrower spacing?! Bingo!
I think the trees are obscuring the forest. With a 1 5/8" balance point or something at least close, a handle spacing of around 4 inches, and a 34-ounce/400-inch model it will groove nicely and bang purty good corners with what are not much more than flicks of the handle. At the handle the lines should never even come close to fouling each other. While I do not suggest doing so one could be reasonably sure of not snagging a line even if the clips were to be left open!
Assuming all else is real close - and let's face it, there is some challenge in screwing up even a second-hand ARF Flite Streak - then you can fly in the face of a lot of experience with CL's equivalent to a '57 Chivvy or continue down the path of inventing non-snagging line clips.
Or maybe look at the control system more closely.
I will tell you this answers a nagging question: Other CL guys in your area can't give decent advice? Ah, but they have been looking at the model. For whatever reason no one took the time to watch the pilot. Okay, not many of us go to that level; but some of us do.
I remember Keith Varley have a terrible time with the last corners of squares and triangles. It looked like a trim problem if one just focused on the model. Keith is an arm-pumper, pulling in some line with each sharp corner. Once I took the time to just watch Keith it was immediately apparent that by the time he had pumped through 2 or 3 corners he simply didn't have any arm left to make the last corner.
What was funny about the deal was that unknown to me Bruce Hunt was also checking Keith's actions at circle center. He turned to me and said, "Well, now we know the problem!" And I said, "Yup."
Dan
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If you have the time to take a look at it, or at me flying, or to fly the thing itself at Eugene (at whatever CG position you want), I'll be grateful.
In the mean time, this is not the only plane this happened to; I can only assume that I'm doing something wrong, so I'm going to go ahead with a positive fix so that I might find out what that wrong something is without having to spend all my time rebuilding planes.
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In the mean time, this is not the only plane this happened to; I can only assume that I'm doing something wrong, so I'm going to go ahead with a positive fix so that I might find out what that wrong something is without having to spend all my time rebuilding planes.
How many handles do you have? What is the spacing on each?
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Two: the one in the picture, which has a spacing of about three inches, and the Fright Streak which is at about 2 or 2-1/2 inches.
Crash #1 was on a different plane, with a line spacing of between two and three inches.
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Hi Tim
Sorry to here about your line problem. I too went through the same ordeal with my last Oriental but mine happened at the
plane end.
I was just getting a good feel of level flying and started to relax and get into the groove when the Oriental took off strait up.
I was shocked there was nothing i could do i tryed down /up shaking the line but the plane just came back down and slammed
strait in.
After close inspection we could see that the lines where snagged at the wing end.
Looks like i need to make better terminations or use some kind of rubber tubing that slides over the hookups. I did see somewhere
where Egor Burger a control line champion uses this kind of saftey device on his stunt planes. Good Luck Bryan
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It is interesting that Da Dirt mentioned having someone whatch Tim fly and not the airplane. I have say and watched many pilots fly, trying to see how I mayself could improve at one time. Most all the top notch pilots barely move their arm doing the maneuvers. One in particular, Billy Werwage, all I see is a little handle movement with him following the airplane. His hand and arm stay centered on his body it seems like. When a plane is balanced right, it takes very little handle movement.
In the day, I had two handles for flying. No. one was the Hot Rock, 4 inch spacing for racing and sport. I did not fly the stunt pattern yet. No. two was the E-Z Just, 5 inch spacing for flying combat and horsing around. The handle I use the most is one I got from Big Iron, which resembles the Hot Rock handle.
Now Tim, after someone does whatch you flying and not the plane, listen to them. It might help. I think Jim Lee gave up on me as I still over control at times. H^^
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Y'know, when I posted this originally I thought that the experts would glance at it and say "phhht!", and maybe a beginner or two would see an inspiration for "training wheels" that would keep them from crashing until they figured out their root cause.
Thanks guys -- I appreciate all the advise.
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If you slowed the control system at the bellcrank/control horns, you wouldn't need to run the line spacing at the handle so narrow that they catch on each other.
I think this is the crux of the matter. First, just try 4" spacing at the handle. It won't make it unflyable: the denominator of the transfer function between you and the airplane response won't change. If you do need the smaller line spacing to make it fly better (and I'll bet you don't if you are moving the handle far enough with the small spacing to snag the lines), then the control geometry on the airplane has inadequate line travel per control surface deflection, which will cause other troubles.
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Tim,
If you look closely at the photo, you'll see that the EYELET is keeping the 'scissors clip' from CLOSING
completely. That exposed end of the clip is what is snagging the opposite line.
A piece of the large hose is probably the easiest solution.
Cheers.
Warren Wagner
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I think the cut end of your "U" is too long. There is daylight between the end of the "U" and the body of the clip, likely enough to easily snag the other line should they come in contact with each other. In addition, if the clip were to have any give or stretch under load, the gap between the end of the "U" and the body of the clip would open farther. Commercial clips I have seen have the end of the "U" cut right at the radius, leaving little if any straight portion parallel to the body of the clip. If the end is cut at an angle away from the body this would also make it less likely that a line would get caught within the clip. This is one of the clips that came with my Fancher Handle kit from Carl Shoup.
(http://i104.photobucket.com/albums/m169/fourshipp/Control%20Line/2012-05-21_12-27-56_20.jpg)
That being said, I also think that if your airplane it trimmed correctly and the control geometry (bellcrank arms, horn arms, etc,) are correct, there should be no reason that one line should ever come into contact with the opposite line clip, barring an extreme recovery after getting blown out of a maneuver or similar situation.
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When talking about handle position, handle movement, body position and so on it is my view that while there are a lot of guys to watch and emulate--especially during the upcoming NWR--one simply cannot go wrong spending 6 minutes or so watching Brett. Yes, I mean the whole flight! Watching multiple flights would be better. I wouldn't find it out of the ordinary to videotape all his flights, whether practice or competition.
It would be worth considering positioning. While there would be something to be learned from the upwind position there is more to be seen and learned from both cross- and downwind positions.
Warning: Like a lot of things which look easy, Brett's rigid insistence on keeping the handle centered on his body and fairly close to his chest is more difficult than one would think in actual practice. For one thing your model must be in quite good trim; in particular, characteristics which cause the model to go slack on the lines all too often see the "solution" to this problem being to arm-pump the thing back into compliance. I am convinced that's the source of all the arm-waving we sometimes see at circle center, not crashing having been viewed as positive reinforcement when getting rid of the nastiness at the model would have been a much, much better plan.
Dan
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Good point. I can remember having to reel in ten feet or so of line during overhead eights.
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I think the cut end of your "U" is too long. There is daylight between the end of the "U" and the body of the clip, likely enough to easily snag the other line should they come in contact with each other.
True -- but I showed my handle to Richard Entwistle on the day that it happened, and he showed me his, and his line clips look not all that much better than mine.
That being said, I also think that if your airplane it trimmed correctly and the control geometry (bellcrank arms, horn arms, etc,) are correct, there should be no reason that one line should ever come into contact with the opposite line clip, barring an extreme recovery after getting blown out of a maneuver or similar situation.
That, and the pilot managing to keep his head on straight are, I think, the primary issue.
Like I said, I'm going to swap things around to prevent this from happening, so that I will be at leisure to figure out the true root cause and fix it. I suspect that if I'm jerking the handle or have some other bad habit, that it's going to take me time to figure out why I do it and stop.