I was wondering if there is any negative effects from adjusting the ailerons so that at neutral they are both slightly lower then the trailing edge of the wing. would this act as a flap or not really do anything at all. they measure 1/16 of an inch lower then the wing. they have more throw going down then up. I haven't flown it like this yet, but I was hoping this would help a little to shorten take offs and slow the landing speed a little. also which direction has the bigger effect the aileron thats down or up? I would like to make the plane more responsive.

what plane?

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.

Can't you adjust it so that is truly neutral? There should be enough adjustment in the threads on the clevis end to adjust this out on both sides.

If you don't know how to do that, let us know what the plane is, flat bottom wing, semi, or symetrical, whatever the design is, and if you have two servos's (one on each wing half) or one (in the center operating both ailerons).

CGr.

As long as the droop is kept small it won't be a problem at all. As you said, it will act like flaps and increase lift a little. I often do this on planes when I add floats to help carry the extra weight

thanks for the replies, it's on my Multiplex Magister. one servo operates the ailerons. I had them adjusted level with the wing and wanted to try this out. I was thinking about modifying the wings for two servo ailerons so I could program flaperons in my TX mainly to shorten the take offs, but if I can get more lift like this that would be nice.

Minnflyer, how much droop do you normally give your planes when doing this? is 1/16 enough or should I give it a little more?

My rule of thumb is 3 turns of the clevises - That way I know how much to turn it back when I'm done.

But 1/16" doesn't sound unreasonable - and you may want more that what I use.

But I DO recommend counting the turns - this way they will both be even and you can keep track of it if you want to un-do it.

the control surfaces on the magister have the wire clamps on the control horns, so I have to shoot it by eye. when I origanally set up the plane I used a straight edge to set the surfaces for the maiden flight then just adjusted with trim from there. I'll give my new setting a try and see if it helps. thanks for the help.

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.

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.

The best thing about more up than down (differential) is that it reduces the "adverse yaw" effect. This can be done with a single servo too.

I have found that the model will usually respond much better if both ailerons are slightly up (not down), especially if the airfoil is flat bottom or Clark Y type. You may find it quite interesting to experiment a bit with aileron position. I'll bet you find the plane flys better with both ailerons slightly up.

unfortunately it's way to windy to fly today, I guess I'll have to wait for a calm day so I can play with the adjustments and see how they effect the plane. I guess it will come down to which I want more agility or shorter take offs.

I agree: In my experience so far, up aileron effects the model quite a bit more than down aileron.

I am not familiar with your specific model and therefore I have no clue as to how your ailerons are configured, i.e. strip, barn-door or what. If they are conventional barn-door ailerons on the outside of the wing wiith flaps/flap area inside you are asking for some "Experiences" in your pursuits.

Listen to Rodney above. He has broken the code.

Full length flaperons or outside ailerons / flaprons can get you into a world of hurt, even if you are a well experienced flier. They attract tip-stalls like flowers attract bees. I don't even try to keep the inexperienced "warbird" drivers, (second airplane) that snap that ARF warbird even though aerodynamically it is nothing but a pure sport (Kaos) model because they will not seek or listen to common advice. Just last year, a fair pilot had a Corsair, .90 or so at the field. He had been trying for several weeks to get decent flights and it was showing considerable repairs. While expressing all his troubles, I suggested the up-aileron using a bunch, about 1/8" at the TE of the ailerons. Then he had a trainer. 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."
Flaperons on the outboard ailerons Not in my fleet.[8D]

Of course, you do as you please.

edited to add "...or outside ailerons / flaprons.."

after reading everything posted, I'm going to change the ailerons to 1/16 up instead of down before I fly it. they are on the outside edge of the wing. I don't want to cause tip stall. thanks for the lesson! there is so much to learn about this hobby. I think aside from the flying part, the maintenance and repair (hopefully more maintenance!!!) as well as learning everything are what make this hobby so addicting. even tho you guys already know, I let you know how my next flight with the magister goes with the aileron slightly up. I'm hoping for good things!!!

thanks again for the help, it's amazing how much money you can save by listening to the voices of experience [)]

Just curious, but the original post was about decreasing take-off roll and decreasing landing speed. Won't having the ailerons raised a bit increase take-off and landing speed?

You mentioned that you can program it into your TX, surely if that's the case for the cost of 1 Servo I can't see why you'd be considering doing it any other way.
Put the flaperons on a switch and if you don't like it or you find it's great for take off and landing but horrible for general flying - problem solved just flick the switch back !!!!!!!!
Not only that but if you're not sure how it's going to react, fly it up high as you normally do and then flick the switch and bring the speed right back and see what happens - again don't like it flick the switch !!!!!!!
Also if it's not enough, land adjust rates on your TX accordingly 20 seconds later you're taking off again !!!!!!!!!!!
Just my pennies worth but I would have thought it's a no brainer ??????

Not enough to notice but may make the plane respond better at slow speeds which is always nice. Actually slightly less likely to stall if takeoff is done at too slow of a speed.

I might be just used to flying my trojan or Super Cub, they both will take off in short distances. the magister takes quite a bit longer. I don't have a lot of stick time on the magister, so maybe with some more practice I'll become more proficent at flairing the plane on landing to scrub off the unwanted landing speed. off hand whats the average take off distance for a 40 size high wing plane? it takes the magister about 80-100 feet. the climb rate has to be fairly shallow or the plane looks like it wants to stall. the tail tends to hang low until the speed picks up, once it's up and gets up to speed it's fine. I set the CG according to the manual, Ive tried moveing the CG forward but it made the take offs longer so I put it back to where it should be.

I agree with those abovepitch em up about 1/16. Kirk (Montague) above is an experience combat pilot and know his stuff. We always flexed the ailerons up a little for more stable flyingall the things he said.

As far as differential is concerned, the aileron needs to travel up a bit more than down. On a sigle servo set up use one of the star shaped control arms and use the two toward the top. That will give you a little more travel in the "push" direction which is "up" on most trainer type planes.

aileron adjustment update:

today I finally flew my magister with the ailerons adjusted upward 1/16 of an inch.
the result was mixed, both good and bad. the distance required to take off was ridiculous. it took the plane almost 200 feet to get enough lift to creep into the air. where I was flying I normally have a margin to abort if I get squirrelly on takeoff, but I used every bit of it to get the plane up to speed and for a minute I thought things were going to get ugly as I was well beyond my point of turn back and still the plane wouldn't lift. just as I was about to hit the big shrubs out in the desert about 50 feet past where the pavement ends I gave it full elevator and missed the bushes by inches. so I noticed a big difference in the distance it took to get the plane in the air. on the good side the plane was so agile in the air it was like flying a different model!!! this thing will throw pure barrel rolls unbelievably quick and is a lot more fun to fly!!! the landing I had today was good, I was able to slowly cut throttle and increase the elevator and flared the plane nicely for one of the best landings I've had with the plane ever. so now I have a new dilemma, I HATE the distance it takes now (I thought the plane took to long to take off before) to take off, but I LOVE the way the plane acts in the air. so how can I fix this??? maybe time for a bigger motor? or does anyone think if I changed the prop from the stock APC 12x8 to a 13x6 that would do the trick of getting this thing off the ground. (I'm thinking of either going brushless or glow) the flight speed is good it's just stupid how long it takes to get in the air. I await your wisdom!!!!

Without going back and reading the whole thread to see what setup you have...

IF you have two servos and a computer radio, you could program them to drop back to their original position for takeoff.

It sounds like you are waiting for the plane to float off the runway without any elevator input. If this isn't what you are doing, correct me.

I can't imagine raising the ailerons 1/16inch would extend a takeoff that much. Don't be afraid to pull the elevator. Most planes can lift the front wheel in 50ft. As you build ground speed, introduce more and more elvator. Just as the plane lifts (6inches), reduce the elevator to keep the nose down and avoid a stall and she should climb nice and easy.

Also, did you notice your elevator trim was off after you adjusted the ailerons?

A lower pitch, larger diameter prop will make a huge differnece in take-off roll. Depending on the RPM of your motor, you're probably not getting the prop to an efficient AOA until the plane gets moving, which makes it accelerate slowly. You'll get better climb as well. So, DO play with props. The more props the better (I think, anyway). If you're using a 12x8, try a 12x7, 12x6, 13x6 at least to start with. I bet you'll like the 12x7 if you can get one. You'll have very little drop in top end airspeed, but you'll have a shorter take off roll.

You can also try using short field take-off technique if you really want to go up quickly. It's a bit tricky, but fun to do.

What's that? Holding slight up elevator while you taxi or something?