Montague
Posts: 4606
Joined: 4/19/2002
From: Laurel, MD,
Status: offline
|
As Minn said, you'll probably be fine.
However, you may run into some funny things if you aren't careful with it. I've seen more than one plane get "pitchy" in the air when the ailerons are lowered. Basically, the plane will feel like it won't hold elevator trim, or in the extreme, it will dart up or down for no apparent reason. Kinda like being tail heavy, but it doesn't feel quite the same on the sticks.
Some models will also develop a strong tendancy to baloon with the ailerons drooped like that.
The cause is a change to the pitching moment of the airfoil, and the effect depends on the airfoil and on the CG and horizontal tail surface and location.
For more acrobatic ability on planes with cambered airfoils (flat bottom and semi-semtrical, but NOT symetrical), doing the opposite, reflexing the ailerons upwards will often make the plane fly inverted better, decrease pitch changes with airspeed and sometimes help the plane track in pitch better.
So, make your changes slowly and carefully, and flight test them well at a safe altitude. Be sure to check out stall handling and what the plane does at high and low speeds and with quick speed changes. Fwiw, my preference on most non-symetrical planes is to put in a bit of aileron reflex, raising the ailerons.
Play with it and see you like with that model, messing around with such things can be a lot of fun.
quote:
Typical aileron differential is to have them travel 3 parts up to 2 parts down. Downward movement has more effect, because the airflow along the bottom of the wing is fastest. (yeah, yeah, Bernouli vs. laminar vs. boundary layer vs. whatever), downward movement has a greater effect. And as long as both are deflected the same amount, they will work like flaps.
I'm fairly sure that much of this is wrong. Airflow over the top of the wing is faster than airflow under the wing.
Also, the upwards moving aileron is much more effective. Having had aileron pushrods knocked off of many many airplanes during combat matches and continued to fly the match, you can really feel the roll rate in one direction become almost nothing, while in the other direction it's almost unaffected. And it's always the loss of the upwards-moving aileron that kills roll response. (losing an aileron is annoying, but far from fatal unless it locks hard over, then it's a bit more exciting).
The differential amount thing is ok, though I'm not sure there is a "typical" amount, as I see all kinds of values. But 3-2 isn't a bad place to start if you want to play with differential. I'd be willing to believe it might be typical in some types of aircraft in particular though.
_____________________________
Kirk Montague Adams
RCCA 560
|
Printable Version
All Forums >> RC Airplanes >> Beginners >> aileron adjustment? 
aileron adjustment? - 
RE: aileron adjustment? - 
After some readjustments he wound up at about 1/16", and he was flying that machine like a true sport aerobatic model. Guess he still does. He kept telling me, "I just don't believe that could make such a difference." 