twinbrother

My Feedback: (7)

Has anyone experienced this effect with their planes? I've flown a few planes and have noticed different response behaviors with the type of ailerons on the planes.

On my GP Super Sportster EP, I originally had it around 3.25 lbs, the stock weight of the plane with a .25 size motor on it. It handled well and responded quickly. This plane has thin ailerons about the length of the entire wing. I'd say the ailerons are about .6 inches wide. When I converted the same plane into a faster one, with a .46 size motor, the weight increased to about 4 lbs, and now the plane responds sluggishly when I use the ailerons. It just doesn't respond the way it did was lighter with the smaller motor. Wingspan is 49".

I also have a .46 size P-51 with a .46 size motor in it. The wingspan is about 58" and weighs in at about 5.5 lbs. This plane too has long thin ailerons, the length of the entire wing, but only about an inch wide. So the ailerons are considered thin. When I turn the plane with ailerons, the response is also sluggish.

In my fleet is also a .46 size Spitfire, 55" wingspan, with a .60 - .70 size motor in it. The ailerons on this plane only span half of the wing, but are wider, about 1.75". The plane is 7 lbs total. However, the ailerons respond very well when I turn the plane.

My .25 size Spitfire with the .46 size motor turns very well. It has the same wingspan as the Sportster EP, 49", about the same weight, 4 lbs, but has the wider ailerons only half the length of the wing. The turning response is very good when I turn the plane with the ailerons.

I thought maybe increased speed would make the ailerons respond better, but that isn't the case with the Sportster EP. The ailerons still responds sluggish. I can only conclude it's the thickness of the ailerons that cause the better response in turns. Seems heavier planes with the long thin ailerons do not like the excess weight it needs to turn in flight. Does anyone with a bit more experience have input on this subject?

Mike Connor

My Feedback: (5)

Ailerons will be more effective if:
They are put out towards the wing tip.
Larger area.
More travel.
Gap is sealed.
Aircraft is lighter or faster.

Jetdesign

My Feedback: (8)

The further away the aileron is from the fuselage, the more it will affect the plane. If you had, say for one wing, .5" aileron spanning the whole length of one 30" wing, you would have 15" of aileron area. However, the aileron portion closest to the wing does virtually nothing, and the portion furthest from the wing has the greatest affect.

Now, if you had a 1" aileron that only spanned the outer half of the wing, 15", you would still have the same amount of aileron area. However, since the entire surface is concentrated further from the fuselage, the whole surface area will be effective.

This is the reason that flaps are generally installed right next to the fuselage, so there is much less force causing the plane to roll.

I forget the science behind it, but I know that there are two ways to increase the effect of a control surface: increasing the speed of air acting on the surface, or increasing the surface area itself while keeping the airspeed the same. The larger surface area with the slower wind speed will have a greater affect.

Tall Paul

I converted my Dyna-Flite P-51 with strip ailerons and a too-rapid roll rate to scale sized ailerons, and flaps.
The roll rate is still too rapid, but the plane looks better.
Barn door ailerons move the moment arm for the surface further out from the longitudinal axis, making them more effective, relative to strip ailerons.

pimmnz

Way back in the early 1960's when 'strip' ailerons first appeared on aerobatic aircraft, this same question was posed. Some even went to the extreme of building two wings, with each setup. the empirical answer was that you couldn't really tell the difference, while flying the model. That being the case, the simplicity of the build of the strip aileron meant that it then went on to appear on most models. And that is probably the biggest difference between the two.
Evan.

rmh

The practical differenceit was easy to hook one central servo to both ailerons -Highly desireable even now - th practical methods for barn door linkages is difficult for some to get right - so next step was two servo a lousy setup at best but easier to do
I have seen guys claim their ailerons stopped working in a dive ( flutter they could not hear) using long thin strip stuff.
as for performance - eithe works
I like full length tapered ailerons thick to thin and wide to narow -
structurally much stiffer and provide excellent response -I also counterbalance the tip shown here is solid lead, forward the hinge line

twinbrother

My Feedback: (7)

After building 10+ arfs and flying them, I'll take the barn door type ailerons over the strip ones anyday. And I rather use the two servos, one for each aileron. The strip ailerons respond way too slow for heavier loads. Thanks for the info. Learn something everyday.

Montague

A lot of plane with strip ailerons also have the servo driving the surface from the root via torque rods. While these days, the barn door ailerons are often driven by two servos. The problem is that long, thin ailerons driven from the root can often flex and twist, and that flex will act to reduce throw at the wingtips, where the ailerons are most effective. Just going to two servos, with the horns mid-way out on the wing will often make the same ailerons with the same bench-measured throw feel a lot more effective in the air for that reason alone.

mjfrederick

The reason they got sluggish is because, like monatgue pointed out, since the airplane is moving faster, the ailerons are able to be twisted by the airflow because they are controlled by torque rods from the center of the wing. The only way to fix the problem in this case (since you can't cut new ailrons out of the wing) is to put mirco servos centered in each wing panel, and put a control horn in the center of each aileron. You'll notice a montstrous improvement. Keep in mind, ailerons work by changing the angle of attack of each individual wing panel, causing one to produce more lift, and the other to stop producing lift. The area of the ailerons is not the only determining factor because you could have barn-door style ailerons on the wingtips of this airplane that are the same area as the ones you have now that would be more effective (and not just because they are on the wingtips). This is because the aileron would be able to change the angle of attack more than the small strip ailerons.

dignlivn

Mr. Hanson

Could you explain " counterbalance the tips" ?

I am going to start a Astro Hog build soon, but would like
to go with "Barn door ailerons ". This will be my 4th build
but the first using these type ailerons. I need to order the "Berkley"
plans, as the plans I have use strip ailerons.

Thanks in advance for your time.


Bob


dignlivn

(edit to correct display of quote)

mjfrederick

Hope these pictures are clear enough to see what has been done. I believe these illustrate what Dick was talking about when he mentioned counterbalanced ailerons. In this case, these are a wing and stab from a Quest pattern airplane designed by Bryan Hebert. The tip of the control surface is angled forward putting some of its mass forward of the hinge line.

dignlivn

Thanks mj,

Pic #3 gave me the idea. I'm researching Barn door
ailerons and read about counter balancing. All for my
Astro hog btw. Thanks again,


Bob

victorzamora

The reason that shorter, wider ailerons placed near the tips of the wing are more effective than strip ailerons is because the center of force is farther out and has the same amount of area. The same area=same force. Same force x farther out from the plane's cg = more torque. The more torque there is , the faster a plane will roll under the same circumstances. That's why people use crowbars. It's just me, though.

da Rock

Counter balance............. two types.

Mass balance
Aero balance


Flutter is caused by magic. The magic happens more often to heavier ailerons. The mass of the aileron contributes to the problem. In most cases, 100% of the mass is on one side of the hinge line. Once the magic starts to push the aileron in one direction the mass of the aileron adds to the problem by giving that movement momentum. So one solution to the problem is to reduce the mass. Another is to balance it. Mass balance addresses that solution. If you weigh the aileron and discover it weighs 1 ounce and you can tell it's CG is one inch from the hinge line, you'd have all the info you need to start that mass balance solution. Your next step is to attach something to the aileron that will carry a 1oz weight 1 inch on the other side of the hinge. The ideal for a perfect balance is just that, perfectly balance the mass of the aileron on that hinge line. You seldom need a perfect balance. Change the amount of unbalanced mass and the flutter speed changes. Change it enough and the airplane can't go fast enough to reach that somewhat balanced surface's flutter speed. Often you only need some percentage of the mass balanced.

One simple way to add a mass balance on ailerons that have an exposed end is to glue an end plate to that exposed end. The plate sticks forward and is outboard of the wingtip. You see those mostly on wings that have chopped off, flat wingtips. OK, wings that don't have wingtips, that just stop at a rib. And the front of that aileron plate might have a strip of lead glued to it. LEAD???!!! you say!!!!! Yeah, it doesn't take much lead, and you're not balancing the entire mass of the aileron, and you ought to be building light ailerons anyway.

The aero balanced surface is illustrated above in those pictures. Those forward projections would also be perfect places to place a small lead weight. But aero balance is usually done with appreciably larger forward area. Look at the elevator of any 3D model. Compare the area ahead of the hinge line to the area behind. The idea is to reduce the aero load on the surface by having the aero load behind the hinge pushing one way at the same time the aero load ahead of the hinge is pushing the other. (Those also benefit greatly by having less slop in the rigging.) Since we're talking about ailerons here, a lot of 3D models have those forward projections on their ailerons too.

It is said that everything has a flutter speed, even a bowling ball. The idea in a lot of cases is to simply move the flutter speed out of the airplane's speed envelope. That works until you let slop into the rigging.

Anyway....... thems the two kinds of counter balances you gonna see mostly.

(And what we usually need is simply less slop in our rigging.)

pipercub6

My Feedback: (16)

Hey Everybody,

No one has brought up the subject of adjusting differential into the ailerons. That may help him without having to change a lot.

Pipercub6

mjfrederick

Differential is not his problem. He's not complaining that the airplane does a barrel roll when he rolls (the result of differential... it probably is, but that's not the issue). He's complaining that the ailerons are not effective enough. Differential is when one aileron direction is more effective than the other aileron (up vs down effectiveness, not left vs right), causing a "differential" in the lift changes. If you meant exponential... well, that's probably not his problem either unless he programmed it in to begin with. If that was a problem, I would hope he'd be smart enough not to be in the aerodynamics forum speculating as to what caused it.