Aileron configuration?
08-12-2014, 01:59 PM
#2
Perhaps you question is part answered by the considering the aerodynamics of ailerons.
For any given size aileron the further out from the fuselage it is the more effective it becomes.
Put another way for a full span strip aileron the outer 1/3 provides 2/3 of the effect, however the drag it creates when it is deflected is more or less constant along its full length.
From this you can see that a 1/3 span aileron mounted from the wing tip is more 'efficient' in doing what it does although a full span strip aileron will be that bit more powerful.
So where aerodynamic efficiency is important (eg a glider) limited length ailerons mounted at the wing tip are used. On a plane intended for 'full house' aerobatics full span ailerons are used. This applies to full size as well as models.
Of course if you want a plane to 'prop hang' the ailerons must go right up to the fuselage to provide control purely from the prop wash.
There are of course issues of the construction of the aileron and how it is moved that can influence their size and how they are mounted.
I hope this helps.
For any given size aileron the further out from the fuselage it is the more effective it becomes.
Put another way for a full span strip aileron the outer 1/3 provides 2/3 of the effect, however the drag it creates when it is deflected is more or less constant along its full length.
From this you can see that a 1/3 span aileron mounted from the wing tip is more 'efficient' in doing what it does although a full span strip aileron will be that bit more powerful.
So where aerodynamic efficiency is important (eg a glider) limited length ailerons mounted at the wing tip are used. On a plane intended for 'full house' aerobatics full span ailerons are used. This applies to full size as well as models.
Of course if you want a plane to 'prop hang' the ailerons must go right up to the fuselage to provide control purely from the prop wash.
There are of course issues of the construction of the aileron and how it is moved that can influence their size and how they are mounted.
I hope this helps.
08-12-2014, 03:13 PM
#4
It seems that if they are more effective at an outer location of the wing, then they would be more efficient, as less would be needed.
I am not building anything, or looking into a new design, I was just asking the question.
Personally, I do not like strip ailerons as structurally they can be tricky. By that I mean, things need to be done to keep them from flexing and not fluttering. Barn door style are harder to build, but they look so much better.
I have a Sun FLy 5 that I added Barn door ailerons too, as opposed to the stock Strip ailerons and have been very happy. It does not seem to perform any better necessarily than my old Kaos did with the strips though.
I am not building anything, or looking into a new design, I was just asking the question.
Personally, I do not like strip ailerons as structurally they can be tricky. By that I mean, things need to be done to keep them from flexing and not fluttering. Barn door style are harder to build, but they look so much better.
I have a Sun FLy 5 that I added Barn door ailerons too, as opposed to the stock Strip ailerons and have been very happy. It does not seem to perform any better necessarily than my old Kaos did with the strips though.
08-13-2014, 06:32 AM
#5
vertical grimmace
Just be careful. More efficient does not necessarily mean more powerful.
The choice of the size and position of the ailerons does depend on quite a number of things.
To determine if one is better than an other would require a careful comparison between two otherwise identical planes.
If your are building a scale design you end up with barn door style ailerons simply because that is what the majority of full size planes use. There must be a reason why that is so.
Just be careful. More efficient does not necessarily mean more powerful.
The choice of the size and position of the ailerons does depend on quite a number of things.
To determine if one is better than an other would require a careful comparison between two otherwise identical planes.
If your are building a scale design you end up with barn door style ailerons simply because that is what the majority of full size planes use. There must be a reason why that is so.
08-13-2014, 05:46 PM
#6
I really got to thinking about ailerons when returning to pylon racing years ago. The wings had changed to have a smaller barn door aileron mid span. The idea was to create a more constant speed aileron, eliminating the need for dual rates as much. A little bit wider chord than had been used previously as well. I am sure, some adverse yaw played a part in this idea as well. Helping to maintain that constant bank around the pylons, without yawing out with slight aileron corrections. I found this design idea has worked great.
08-14-2014, 10:29 AM
#7
My Feedback: (1)
If your are building a scale design you end up with barn door style ailerons simply because that is what the majority of full size planes use. There must be a reason why that is so.
08-14-2014, 09:41 PM
#10
I am going to go out on a limb here and say that by and large (in my experience) Flaps are used mostly to create drag in model airplanes than anything else. Granted, many heavier scale models require them, but I will assert that many of these planes could be landed still without flaps.
08-14-2014, 11:54 PM
#11
It seems that if they are more effective at an outer location of the wing, then they would be more efficient, as less would be needed.
I am not building anything, or looking into a new design, I was just asking the question.
Personally, I do not like strip ailerons as structurally they can be tricky. By that I mean, things need to be done to keep them from flexing and not fluttering. Barn door style are harder to build, but they look so much better.
I have a Sun FLy 5 that I added Barn door ailerons too, as opposed to the stock Strip ailerons and have been very happy. It does not seem to perform any better necessarily than my old Kaos did with the strips though.
I am not building anything, or looking into a new design, I was just asking the question.
Personally, I do not like strip ailerons as structurally they can be tricky. By that I mean, things need to be done to keep them from flexing and not fluttering. Barn door style are harder to build, but they look so much better.
I have a Sun FLy 5 that I added Barn door ailerons too, as opposed to the stock Strip ailerons and have been very happy. It does not seem to perform any better necessarily than my old Kaos did with the strips though.
08-15-2014, 02:30 PM
#12
10-13-2014, 10:43 AM
#14
1. Barn-door (B-D) ailerons allow one to adjust for wing wash-out which can provide tremendous favor over strips where the angle-of-attack (AOA) can be set to decrease the chance of the so-called "tip stall" which can provide a lot of heart-burn for the heavy scale model, or even the sport models, and not just for T.O. and landings.
a. Way back when I did some serious Scale Warbird racing, I had a small little Spitfire. It was a beautiful model and flew great except for Take-offs which were very "squirrely". Landings good until just before touchdown when snaps could happen. I finally got about 8* up in the ailerons. What a difference? Smooth Easy and Easy!
That did not happeen when a Bear-Cat came up and removed the aft fuselage from the Trailing Edge of the wing. Darn, all squirrly again!
2. For a time local clubs had a pylon-racing thing going. 4-star racers. Take-offs and landing with the required 9-7 props and ST 40s were generally BAADD! Finally they allowed a 5" taper on the outer part of the ailerons. The "squirrels" had to move out to other places.
3. For all my Scale models I use about 3/4 inches aileron-UP to start. Work from there.I have suggested such to many scale-model fliers. They all LIKED it right off. One big (about 70" w/s) Corsair pilot was having trouble with his Corsair. I suggested rolling up the ailerons for about 3/8". It was a sport model. I suggested he set the aileron-up on different flights. He said that the way it was flying, he was not touching anything.
4. Strip Ailerons giving you some bad? Cut the ends off a few inches from the end. Start setting the strips back on using some UP. Then adjust to your liking. Depending on your flying, say significant aerobatics, you may find that simply having a non-moving strip of several inches will do the trick. Different models - different strokes.
10-13-2014, 12:50 PM
#16
Barn door ailerons can use more. Test gently.
Strip ailerons have to be cut near the end depending on wing span, and glued into place. I usually use 4-6" depending on wingspan.
DO NOT just raise strip ailerons as that is not the trick. The trick is to get some wash-out out close to the wing's outer space. Let us know what you find.
In free flight we twisted the wing a bit. Made the model much more stable.
If you have the chance to look at any real large airplane look from the back and look at the trailing edge. It TWISTS big time from root to end.
Most man-carrying machines have a twisting wing. Many have lifting airfoils at the base of the wing and symmetrical at the end. Also flaps that can be let out in small increments giving more and more twist during the landing and take-off times. At least mine did,
. T-37, T-33, T-38, T-29, B-47, C-123, Lear-Jet, 737, 727, DC-8, DC-10.
10-13-2014, 03:44 PM
#17
I was wanting to see how it may calm my DR1 triplane on take off and landing. For some reason, this one, ( i have built 2) is more difficult on the ground. I would like to calm it down some. Obviosly, the ailerons on this aircraft are very much concentrated on the tips of the top wing.
10-13-2014, 06:37 PM
#18
I was wanting to see how it may calm my DR1 triplane on take off and landing. For some reason, this one, ( i have built 2) is more difficult on the ground. I would like to calm it down some. Obviosly, the ailerons on this aircraft are very much concentrated on the tips of the top wing.
I asked the instructor why was that. He said that the airplane was not flying worth a "Shoot" so he wanted to add more lift. Each attempt to fly resulted in a snap and spin-out. I don't know how the model stayed together.
I finally convinced them to redo the linkages and place all 4 ailerons slightly UP, about 5* or so. The instructor made some words but the student wanted to try it. We balanced out the model a bit better, checked the CG again and I explained the aeronautical situation. The first flight was great. It took off very well, flying smooth and soon was doing basic maneuvers very well. They shot several landings and all was well. I went on about my business. They made several flights and the student took home a very good flying machine. It was some type that I did not recognize, certainly not scale. That was several years ago, maybe 5 or more. The model did show up now and then for more fun flying.
10-13-2014, 06:56 PM
#19
Aerodynamics are not very well understood generally by club members. No biggie, that is why we have the forum!
Your instructor obviously had an aileron confused with a flap. Hence why you need to be careful with the strips. I knew that something would come out of this thread of some benefit.
When I was flying combat, with the long wings, we had flutter problems with the strip ailerons. The fix was to clip back the aileron at the tip, tapering them back around 3"-4". The other solution was as you mentioned, gluing fixed trailing edge material at the tip. I would assume that the tip vortices add or create the flutter issue here. You could here the sound when you went fast. Slow down and it went away. Tapering the ailerons eliminated it, and that became the standard.
Your instructor obviously had an aileron confused with a flap. Hence why you need to be careful with the strips. I knew that something would come out of this thread of some benefit.
When I was flying combat, with the long wings, we had flutter problems with the strip ailerons. The fix was to clip back the aileron at the tip, tapering them back around 3"-4". The other solution was as you mentioned, gluing fixed trailing edge material at the tip. I would assume that the tip vortices add or create the flutter issue here. You could here the sound when you went fast. Slow down and it went away. Tapering the ailerons eliminated it, and that became the standard.
10-14-2014, 07:11 AM
#20
Senior Member
Calming the tips down often gets rid of snaps. When they've got ailerons right out to the tips, they contribute to the possibility one side is going to snap. It's going to be the side with the down going aileron about 10 out of 10 times.
Washout is good on approach, no matter how you help it to happen. Washin isn't.
Washout is good on approach, no matter how you help it to happen. Washin isn't.
05-08-2015, 09:58 PM
#21
Strip vs Barn Door Ailerons.
Back in the old days almost all Precision Aerobatic models used strip ailerons rather than barn door type. The main reason for this was that the old servos didn't center very well, and this centering problem only caused a minor deflection on a strip aileron. If used on a barn door aileron this same centering problem caused a larger deflection due to a lot wider barn door aileron. Also contributing to the problem was the fact that no body had thought of moving the servos outboard in the wing panel. Everyone was still putting the aileron servo in the center of the wing and using bellcranks to work barn door ailerons. The servo centering problem along with the slop in the old style linkages associated with bellcranks really exaggerated the poor centering of a barn door type aileron. Now days we have servos that center near perfectly, along with moving the servos outboard in the wing panels, and excellent control linkages. Now barn door ailerons can be made to center perfectly making for more precise flying. Just some more of my Ancient Knowledge.
JERRY
05-08-2015, 11:29 PM
#22
My Feedback: (1)
Well the real reason for strip ailerons was ease of building. While Hal deBolt used them on his 1962 Viscount design, he may not have been the first. The was also at least one designer from the mid-60's that used dual aileron servos, but since servos cost $40 back then (about $250 to 300 bucks in today's dollars), nobody jumped on the bandwagon back then.
05-13-2015, 10:21 PM
#23
Hi Bob...wasn't it Ed Izzo that "invented" strip ailerons?
I know he has been credited with the first use of foam wings...and I recall pitting next to him and his wife Louise at a few pattern meets back in the 70's...telling tales...seems to me, IIRC that it was either Ed or Pappy...?
I know he has been credited with the first use of foam wings...and I recall pitting next to him and his wife Louise at a few pattern meets back in the 70's...telling tales...seems to me, IIRC that it was either Ed or Pappy...?
05-14-2015, 07:46 AM
#24
My Feedback: (1)
It might be. Both most likely attended the same contests in the early 60's. Got to remember that 8 channel, then 10 channel reed systems were only about 3 or 4 years into production at that time, and not too many being flown due to costs and complexity. They didn't even have six frequencies on the 27 mega-cycle band until 1958.
04-07-2016, 05:29 AM
#25
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how much of this issue is contributed ease of building ?......strip elevators are so much easier to build onto a wing than barn doors and if they work reasonably well, I think there is a lot of incentive for designers of planes to include them in the design, instead of barn doors.
that's not to say they are better in any way,....just that their design is allot more "novice builder friendly", which sells more kits or plans, to any level of builder, for that matter.
that's not to say they are better in any way,....just that their design is allot more "novice builder friendly", which sells more kits or plans, to any level of builder, for that matter.