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


 

Posts: 341
Joined: 9/26/2007
From: San Francisco Bay Area, CA, USA
Status: offline 		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
       Post #: 1

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


 

Posts: 2015
Joined: 4/17/2006
From: Cundletown, NSW, AUSTRALIA
Status: offline 		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.

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Good Flyin Mate. Keep Thyne Airspeed up, lest the ground arise & smite thee, Allan.

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


 

Posts: 341
Joined: 9/26/2007
From: San Francisco Bay Area, CA, USA
Status: offline 		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

(in reply to alan0899)
       Post #: 3

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


 

Posts: 63
Joined: 2/7/2002
From: Mt. Pleasant, PA, USA
Status: offline 		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 .

MTY

(in reply to alan0899)
       Post #: 4

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


 

Posts: 589
Joined: 11/16/2006
From: Memphis, TN, USA
Status: offline 		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.

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


 

Posts: 341
Joined: 9/26/2007
From: San Francisco Bay Area, CA, USA
Status: offline 		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

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


 

Posts: 106
Joined: 10/21/2006
From: Bryant Pond, ME, USA
Status: offline 		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.

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


 

Posts: 735
Joined: 2/8/2002
From: Houston, TX, USA
Status: offline 		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

(in reply to crasherboy)
       Post #: 8

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



Posts: 8888
Joined: 10/4/2002
From: Burnaby, BC, CANADA
Status: offline 		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.


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Proudly wasting balsa since 1965.

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


 

Posts: 45
Joined: 10/14/2005
From: Grand Rapids, MI, USA
Status: offline 		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.

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.

(in reply to BMatthews)
       Post #: 10

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



Posts: 4630
Joined: 6/23/2002
From: Palmdale, CA, USA
Status: online 		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.

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



Posts: 213
Joined: 2/11/2002
From: St. Marys, GA, USA
Status: offline 		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

< Message edited by Capt. Crackup -- 2/26/2008 11:56:12 AM >

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



Posts: 9930
Joined: 12/12/2001
From: slc, UT, USA
Status: online 		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 .

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Libby

(in reply to Capt. Crackup)
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RE: Flaperons may cause tip stalls? - 2/27/2008 4:35:28 AM   
Wine Country Flyer


 

Posts: 123
Joined: 9/21/2003
From: Santa Rosa, CA, USA
Status: offline 		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

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


 

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