Flaperons may cause tip stalls? (Full Version)

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Khatsalano -> Flaperons may cause tip stalls? (11/13/2007 1:52:00 AM)

Hi everyone.

I just finished building my E-flite P-47 and it's been super fun ( http://www.youtube.com/watch?v=6OxI9JNPc04 ). I currently have a Y-Harness for the ailerons but I have a 7-channel DX7 with an AR6200 Rx so I can definitely use the flaperon option as far as my hardware and software goes. But... I read here ( http://www.wattflyer.com/forums/showthread.php?t=4879 ) that flaperons are a bad idea on this particular plane because the ailerons are located so far out towards the tip of the wing -- the warning was tip-stalls at lower speed.

My question to you experts is, sure, if you get low enough speed on a fixed wing, you are likely to get a tip stall on any plane. But, will it increase or decrease the chances of a tip stall or other undesirable/unsafe effects, if I use the flaperon option instead of the standard Y-harness on this P-47? I don't really understand if using the flaperon function will make landing this plane easier or harder.

Thank you very much in advance!

- K



alan0899 -> RE: Flaperons may cause tip stalls? (11/13/2007 2:02:56 AM)

G'day Mate,
The flapperon function allows the use of 2 servos for the ailerons plugged into 2 separate channels of the RX, then the TX mixes them automatically, saves using a "Y" lead. BUT, there is no rule that says you must use the flap function, so just fly it without deploying the ailerons as flaps, & no problem.



Khatsalano -> RE: Flaperons may cause tip stalls? (11/13/2007 2:10:49 AM)

Indeed, that is true and it's nice to have the option... I'm still curious as to the effects on this particular wing configuration how it would affect the aerodynamics. : )

- K



Champ-RCU -> RE: Flaperons may cause tip stalls? (11/13/2007 2:13:56 AM)

Khatsalano, Using ailerons as flaps is a very bad Idea. Will cause tips to have an increased Angle of attack and therefore will stall before the root. That is why most heavier scale planes design in some washout in the tips. (Washout is with the tip trailing edge raised, therefore decreasing AOA and delaying tip stall till after the root has stalled. Giving a more controlled stall and some warning of an impending tip stall.)

If you want to try using the ailerons as flaps I would put a plastic bag in the fuse so you can get all the parts back in one trip[&o].

MTY



highhorse -> RE: Flaperons may cause tip stalls? (11/13/2007 2:20:39 AM)

If they were full-span ails then would be dffnt story, but w/ just at the outer 1/3 (?) or so, I agree w/ champ...bad BAD idea.



Khatsalano -> RE: Flaperons may cause tip stalls? (11/13/2007 2:23:37 AM)

Thank you for your feedback. The plane is very landable as you can see in the video without flaperons, but I wanted to know the effect of using this option. Your explanation was clear. I wish the wing was strong enough where I could cut out flaps on the 2 inches of the wing close to the fuselage, but it looks so thin I'm not sure if this is a good idea either.

- K



crasherboy -> RE: Flaperons may cause tip stalls? (11/13/2007 3:36:31 AM)

I am by no means an "expert",but IMHO regular flaps would be the best way to go. Other that that if the wing has a proper amount of wash out ,etc, then flaperons might work. But if it were me I would look at regular flaps.



beepee -> RE: Flaperons may cause tip stalls? (11/13/2007 6:14:42 PM)

Throw rocks at me if you like, but the proper way to use barndoor ailerons as flaps is to have them pitch UP (not much) in flap mode. That will reduce the tip stall tendancy and add washout to the wing.

Bedford



BMatthews -> RE: Flaperons may cause tip stalls? (11/13/2007 6:18:51 PM)

Even with some washout using standard tip located ailerons as flaperons is NOT a good idea. The drooping of the surfaces will raise the angle of attack over the area with the flaperons to a much higher positive angle that will totally counter the washout that you put in there to reduce tip stalling in the first place.

If you're looking for something to play with and want to add some drag to the model during landings try SPOILERONS as a mix instead. It's the opposite of flaperons. Deflect both ailerons up instead of down. This acts to add even more washout twist to the wing so it's even more tip stall resistant and it kills the lift at the tips so the center has to work harder to hold the model in the air and that adds the drag you want to steepen the glide slope to something that is easier to drop into place.



qwerty3 -> RE: Flaperons may cause tip stalls? (2/18/2008 3:21:28 PM)

My one experience with flaperons was not very good. I had (still have) a GP kit-built "Big-Stik 20" that was originally set up that way - 2 servos on the wing, 'flaperon' control on the transmitter.
Flying results: Helped some to slow down the landing - not a huge difference as I recall. I forgot to 'put the flaps back up' for a go-around: the airplane jumped up to about 15 feet in the air, and I had almost no aileron control - even at full power. I'm not sure if I'd throttled back, but ended up stalling in from about that 15 feet - one wing first. [:o]

After repairing that, I switched back to 'standard' ailerons.

I do want to try the 'spoileron' idea on a Spirit 100 glider, to see if that improves the 'tip stall"iness of it.



Tall Paul -> RE: Flaperons may cause tip stalls? (2/18/2008 5:44:33 PM)

Flaperons on scale planes are built-in tip-stalls.
On gliders, they'r quite useful... if you recognize that the roll response degrades rapidly with flap-down deflection.
The drag from the down going flap overwhelms the change in lift from the upgoing flap on the other side, so the plane will begin to turn opposite the commanded direction.
Quite confusing when first encountered, and of little use.
Inboard flaps on scale planes are much better.. these automatically increase the angle of attack at the wing ahead of the flap, making the outboard wing have "virtual" washout.
And the Jug needs the nifty look of gear and flaps down when approaching.



Capt. Crackup -> RE: Flaperons may cause tip stalls? (2/26/2008 11:54:12 AM)

I am here to tell you that Flaperons can be an effective option for your airplane. As with flaps, the flaperon function should be tested up high and also like flaps, flaperons are a low speed option. I currently us flaperons on 3 models and they make a hugh difference. I use them on a Tiger 60 with a 91 four stroke, a TwinStar with twin FX 25s, and a Dual Ace with twin TT pro 46s. On all 3 models the flaperons allow for slower approach and landing with a "flatter" attitude. You do not need much. Start with about 10-15 % and test from there. Also be advised that twins are MUCH MORE sensitive to flaperon trim so perform initial testing up high. one last thing, I also use them on a senior Telemaster for windy days only on the Telemaster they are Spoilerons. Skip D



dick Hanson -> RE: Flaperons may cause tip stalls? (2/26/2008 6:23:42 PM)

If you stick wit a typical scale P47-- the answer wil be different than if you have -for example a converted old NOBLER which is now an RC aircraft -- and stil very light

OR -if you are doing a profile version of a P47 with a 10 oz ft wing loading.
The rules -as you apply them -- are heavily dependant on wing loading.
Back to my "first law of aerodynamics".
If it is light enough , the rest of the rules don't matter .



Wine Country Flyer -> RE: Flaperons may cause tip stalls? (2/27/2008 4:35:28 AM)

I use flaperons on my H-9 P40. I only deloy them for landing and they do make it glide farther. but it sure sets down nice.
John



AA5BY -> RE: Flaperons may cause tip stalls? (3/2/2008 3:33:51 PM)

Very interesting discussion. As can be seen, there are those who find flapperons effective on some planes and those who've discovered peril for using them. My addition to the thread details two cubs.

One is an anniversary goldberg with a saito 50. Flapperons with only a slight bit of deflection for landings are used on still days without a headwind. Some rudder mix counters decreased roll response. The plane has no tip stall tendencies.

The other cub is a World models with a little longer wing and having a saito twin 100. It will tip stall fairly easily but is tamed by mixing a bit of up trim to both ailerons at lower throttle settings to simulate wash out. I wouldn't even consider configuring the ailerons as flapperons on it.

So... here are two varying models of the same plane that are treated quite differently in regards to the question in the thread.



skylark-flier -> RE: Flaperons may cause tip stalls? (3/4/2008 7:32:08 PM)

One quick note on the idea of "spoilerons" on the Spirit-100. I've had one flying in just exactly that mode for 5 years now and have never had the slightest problem with it.

My original idea for the spoilerons came from an old Aquila that I flew in the 1970's - which was originally built with just the standard spoilers. I wanted to see if I could combine the 2 functions and come up with an "aerobatic-capable" thermal sailplane. It's not really "aerobatic" in the true sense of the word but it DOES do rolls fairly decently as long as you use both the spoilerons and rudder to get through them (spoilerons lose near-total function once inverted - just ask any old WW-II P-61 Black Widow pilot).

Anyway, the Spirit will survive spoilerons, and it's kinda fun with it.

Dave



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