Ailerons and flaps/anybody figured out what they are for yet?

More dumb questions rolling around in my mind. My craft is a Bushmaster from the late 1980's. Supercub airfoil, wings one bay longer than Supercub, squared off tips. My flaps and ailerons are nearly equal in length. As I am sitting here, I cannot remember exactly the measurements. but around 90 inches or a bit more each. The roll rate when slowed down on approach, and just above stall, right before touchdown, seems sluggish to me. Feels a little slow to pick up a wing that is not wanting to stay level. I am wondering if anyone has experimented with flaps and ailerons, that are increased in dimension. from leading edge to trailing edge, and how much difference it would make. Further, I am wondering if changing the shape of the flaps and ailerons, would screw up the airfoil of the wing, unless you also built different wing ribs. To the uneducated, it seems to me that one might have to make shorter wing ribs, to accomplish making more of the wing trailing edge as aileron. I am wondering if one would have to make a large change in the front to back dimension of the aileron, or if a small change would result in appreciable changes in performance. Obviously I am not an aeronautical engineer. I keep thinking of another project, which might improve upon what I have. I've been tempted to create another set of ailerons, with provision to attach a metal tab onto the trailing edge and then go out and see what happens. This would obviously increase the loading on the hinges. Any of you guys out there with lots of experience and intuition, willing to take the time to comment? Thanks! Ed

First, are your ailerons extended out to the tips? If not, that will create precisely the condition you describe. Many modifiers for years would extend the wings, square the tips, and leave the stock ailerons in place. That really slows the roll rate.

Bear in mind, though that longer wings in and of themselves will slow roll rate.

MTV

Ailerons are extended to the tips. I may be all wet here. Years ago, I flew a stock 150 SC, with a Sorenson belly tank and spray booms. As I remember it, heavily loaded, its roll was quite responsive. Climbing over the hills of the Palouse, in Washington, spray on, often it was close to stall, and yet ailerons felt comfortably responsive. It's a long time ago, and I have not flown an SC in recent times. Maybe the only issue is the memory. Ed

You didn't mention VG's on your plane. I have a C-90 powered J-3 and I could get off the ground before I really had aileron effectiveness. I installed the Micro Systems VG's and was amazed at how much more effective the ailerons were at low speed. Now, if it's flying, have good roll control. Simple, light, and effective. Several other benefits too. In my experiance, increasing the cord of the ailerons make them even heavier on the controls, and produce more adverse yaw. As a last resort I would conside spoilers as an alternative. Much lighter and probably less work. Check out the Heilo Courier or Stallion series aircraft. They use spoilers and ailerons for roll control. But I would try the VG,s first if you don't have them.

Steve

VG's, definitely... also, the aileron-wing gap is too large on Super cub wings. Making sure your wing is rigged with the right amount of dihedral will give you more roll response with rudder input.

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Jerry Burr did a lot of work on this...

VGs are probably easiest. I wonder if spades would help?

Remember the slower you get the more you need to use the rudder to lift a wing, long after the ailerons quit the rudder is still your friend.

Glenn

aviationinfo said:

VGs are probably easiest. I wonder if spades would help?

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Maybe Tim will jump in, he added spades to his 2 + 2

Glenn

me $ 00.02 here ->

The Scout has strong lateral stability (i.e. 37' high wing) Have VGs, and alieron spades. Crosswinds, slips. etc do not require "a lot" of stick force.

Your milage may vary.

I appreciate the responses. I have thought of VG's. Not for those reasons though. Ive been told that a set of VG's would make the stall characteristics nicer, and that a set under the horizontals along with a gap seal, would increase the effectiveness of the elevators. At present I have a nice slow stall, and adequate elevator authority. I think I will take the advice given, and install a set of VG's, and go flying. Using the rudder to level the wings, as suggested, is kind of intuitive for me, but my rudder is very effective and it is easy to get out of sync between the power of the ailerons and the rudder, and quickly I am going in a direction that is not entirely parallel with the runway.

I have seen ailerons with extended chord that had a fence on both ends ie, at the wing tip (squared off wing) and at the inboard end of the aileron. Had lots more effectiveness at slow speeds. Experimental airplane, of course.

Interesting; I would sure like to see a picture or example of aileron fences. At first blush it seems like that could be an idea that would be easy to try on the experimental.

Extending the chord on the aileron will effect the aileron center of gravity in relationship to the hinge point. You might get flutter. Wider chord ailerons may also increase adverse yaw.

Some images from google.

Aileron spades will help lighten stick forces, but will not improve the roll authority.

VG's are the first order, here.

On a long Cub wing, roll spoilers such as the HelioCourier are very effective for improved roll authority and also balancing yaw forces when using drooped ailerons. I have done this on an extended, squared-off wing with long flaps and ailerons, aileron droop, and Wayne Mackey slats. Pure joy to fly, actually very easy to fly very slow....and it doesn't care if the a/c is empty or at gross weight. It is a sweetheart either way.

I have tried aileron stall fences...simple......aluminum sheet that is fastened to the aileron end-ribs. I tuft tested and didn't find any great reason to keep them...this was on a round tip, unflapped Cuby with very good roll-authority to begin with...so......

"Aileron spades will help lighten stick forces, but will not improve the roll authority."

I was "told" spades do... several aerobatic pilots say. It is not a lot (but adds small amounts) of lateral force. My fear is that an aileron spade may be hit by a bird. Spades just do not look right to me, but I "grin and bear it". Leaving them on, I hope.

8GCBC said:

"Aileron spades will help lighten stick forces, but will not improve the roll authority."

I was "told" spades do... several aerobatic pilots say. It is not a lot (but adds small amounts) of lateral force.

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.................Okay.

Dave Calkins said:

.................Okay.

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A friend was test pilot for a company that builds aerobatic and normal category aircraft. I asked him about spades. He responded that he'd flown the airplanes with one spade only, and saw no effect at all, except stick forces were a bit higher. But, no uncommanded roll.

MTV

mvivion said:

A friend was test pilot for a company that builds aerobatic and normal category aircraft. I asked him about spades. He responded that he'd flown the airplanes with one spade only, and saw no effect at all, except stick forces were a bit higher. But, no uncommanded roll.

MTV

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That makes me feel better about my bird strike paranoia. If the alieron spade gets ripped off or bent I can still fly home!

8GCBC said:

That makes me feel better about my bird strike paranoia. If the alieron spade gets ripped off or bent I can still fly home!

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As long as it doesn't take the rear spar and aileron with it.

Glenn

A better way to get light feel would be re-locating the hinge-line on an extended chord Cub Aileron.

Spades are an "easy" way to achieve the light controls. Again, I do not believe they will augment authority, but will lighten the forces at the stick.

cubdriver2 said:

As long as it doesn't take the rear spar and aileron with it.

Glenn

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On a MASSIVE strike, true the spar/aileron MIGHT go with the spade into never never land! Anyway, I felt good for a moment.

Not sure how this would apply but an engineer friend told me about micro Vg's that NASA has been experimenting with on flaps. The size he mentioned was something like 7/16" long and I think just 1/16" high; 1/3 the cord distance from the leading edge of the flaps. It increased the efficiency of the flaps and lowered stall speed. Here is an article I found from NASA on the subject. Sounds interesting; wonder what it would do for ailerons.
http://www.nasa.gov/centers/langley/news/factsheets/Micro-VG.html
Marty57

Dave Calkins said:

I have tried aileron stall fences...simple......aluminum sheet that is fastened to the aileron end-ribs. I tuft tested and didn't find any great reason to keep them...this was on a round tip, unflapped Cuby with very good roll-authority to begin with...so......

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I tried the same thing on my 185 flaps. I screwed an aluminum fence with a 2" flange top and bottom on the outboard end of one flap. I figured that one wing should be heavier than the other at some phase of flight. Absolutely nothing. Total waste of time other than increasing my personal knowledge base.

If you seal the wing-aileron gap, (on a cub wing) you will increase roll response.

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Extend the flap gap seals to the outboard end of the ailerons.

You guys are the best!! Thanks for all the help. You all have taken the time to really be helpful. Gap seals are installed properly. I never thought about the possibility of creating flutter in flaps and ailerons, by altering their dimensions relative to the hinge axis. Probably not smart to go hanging some tabs on the trailing edges to see what it would do. I haven't felt that control pressures were troublesome. What I am able to take away from this discussion so far is that some VG's s will be installed as soon as possible. It is also an intriguing idea to try mini VG's on the movable surfaces themselves. Unless I am missing something, there would not be a lot of downside to experimenting with that. I have had a lot of fun with this airplane. Initially it had a ford v6 hanging on the front. It worked fine for 140 nose heavy hours, but I just could never trust it. In going to the lycoming 360 with constant speed prop, I took a couple of hundred pounds off of the nose. It went from being way nose heavy to acting like a cub. It also went from being a 105 to 110 mph airplane to 125 to 130 with the power pulled back some. I have to pay attention and pull it back if descending at all or it wants to go 140 plus, and I start wondering what is a reasonable VNE and what might come loose and fly off. I am just not sure how fast a person should let those extended supercub wings go. When I compare the published speeds of the pacers to the supercubs there is a significant difference. I can't figure out why the bushmaster is so much faster, and I'd really like to avoid that velocity where something could come apart in turbulence, or start fluttering. It's interesting to read here and sense the passion people have for their airplanes. I am a tall, stiff old guy that should push back from the table a little sooner. Getting into a supercub for me is not all that easy. The bushmaster is for me at this time the cat's meow. I will get busy implementing some of these great suggestions, and really do thank you all again for the excellent and helpful comments. Ed

If you put VG's just forward of the flaps, make sure you first have them along the leading edge of the wing, so that some laminar flow can get to the rear VG's....

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You've got me interested in the Bushmaster, now....

My testing of VG's on the leading edge of the flaps resulted in no slow speed improvement. There may be ways to get improvement, but I did not find any.

Also, consider that a vortex spinning off the "normal" leading edge of the wing VG's, might be "unspun" by another set of VG's aft of them......probably a small thing, but just an idea to look at.

Dave Calkins said:

might be "unspun" by another set of VG's aft of them

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Very good point.
As we know, toilets flush backward south of the equator, so it follows that counter-rotating vortexes could well be a problem. Of course, it also makes a difference whether we're in US or Canuck air (like the O.M. thing) or if we're flying/turning up/down wind. So much to consider! A Doctorate opportunity is looming here!
[/smartass]

Dave, Where on the leading edge of the flap did you install the VGs? How far back? It stands to reason that they ought to help the flaps since they do deflect at a considerable angle to the relative wind. In my view they should work here as well as on the wing. Do you think that mounting them upside down in the cove above the flap would make any difference? Have you taped any yarn to the trailing edge as part of your test to observe the airflow both with and without the VGs? I find it interesting that your test did not show any enhancement. Perhaps the Cub in not enough of a high performance airplane for the flap VGs to be effective?