I finally got to plug in the aileron servos of my .40 sized Miles Sparrowhawk. It is a dual servo setup. When I turned the radio on, both of the ailerons neutral throws are about 1/4 of an inch above the TE of the wing on the fuselage side. This plane has been flown before by another owner, but I have never seen it in flying condition and I had to put my own reciever and Y-harness in it. Are the throws of the ailerons OK or should I move them so they are level to the TE of the wing? If I don't how will it effect the flight characteristics?

probably be best to put them in line with the TE of the wing to start with.

probably also get more answers in the "questions and answers" forum

Possibly raised to give a bit of 'washout' effect, Miles aircraft known to be a bit 'tip stally' if a bit overweight, or else your radio has a slightly different centre pulse than the previous owners. Seems a bit much, reduce 'washout' to 1/8" and fly, assuming movement and centering is ok. Remember the bit about the tip stalls if the model is heavy, land with a bit of airspeed, do 'wheeler' type landings, don't attempt to 3 point until you have a handle on the actual characteristics of the thing.
Evan, WB #12.

I "maidened" the plane today, and it flew great. Even with the 1/4" washout it was still 'tip stally' on landing. This was my first flight of a plane with a high wing loading though, so that may be most of the problem.

If it's tip stalling, you have an incidence issue with one wing tip. IE a warped wing. Tip stall is just that, tip stall. Not tips stall. One tip is stalling before the other one does causing one wing to drop suddenly. This is caused by the leading edge of one wing being at a higher angle of attack than the other. Put an incidence meter on the tips and be sure they are reading the same. If they read the same, then one wing is heavier than the other.

Hope this helps,

Tip stall does not necessarily mean there is anything out of kilter
If themodel is slowed to minimums -then yawed or simply eing held in a slight crab - the one panel is flying faster than the other - at least IT thinks it is .
so one panel drops first
You can check this out very easily and safely doing straight ahead stalls then bumping in rudder
On pattern planes in the past, it was almost always the case that a new model would "break" right -or sometimes "left " going into a spin.
In practice it was easy to decide which then, holding slight opposite rudder the break would occur straight ahead -or the thing would mush along. depends on the setup
anyway light plane heavy plane - all the same - even a perfectly straight model will break one way if there is some bias to EXACT straight ahead flight.

Mr. Hanson: Your post is very accurate. BsSmith's post #4 does not mention any bias influences other than vanilla landing. I assumed he just lined up with the threshold and flared. IE slipping the plane in was not mentioned by BsSmith when the tip stall happened.

It always a great read to take in your post and give them thought. We share a common interest. My thoughts on tip stalling in a crab do not involved one wing flying faster than the other. One wing flys faster only for a second when the rudder is applied, and the forward wing moves into position. If the plane does not tip stall at that point, you have enough airspeed over both wings to survive that rudder input at such a slow speed. If your plane tip stalls after that the wing in the rear postion stalled due to two (2) factors:

1. The leading edge of the rear wing is more swept than the forward wing (depending on design). Most Extra's, Yak's, Caps, etc have 5 degrees of sweep per wing. In a crab the forward wing becomes a straight leading edge wing, while the rearward wing goes to 10 degrees sweep. Assuming a 5 degree crab.

2. Part of the rearward wing (inboard part) is hidden by the fuse as seen by the flight path. That makes for less squares lifting on the rearward wing.

Put 1 and 2 together and we get stall of the rearward wing at slow speeds. Both wings are traveling through the air at the same speed once the crab is established since both are attached to the same fuse.

Just my thinking on this, I do love to read and take in Mr. Hanson's post on these "flight" questions.

My addition would be that if simulated washout is used, it might be mixed at lower throttle only so as not to disturb full power flight.

I agree with the mixing, the plane was very squirrely during some of the faster passes, but that may have been because the plane is more sensitive than I'm used to. The radio I'm using now is a basic 4 channel radio, but I have a computer radio coming and I will mix it. This was my first plane with a high wing loading, so that is most of the problem with the stall prone landing, I tried to glide it in like I would do with a trainer and it didn't like it. I will have to try using a higher throttle on landing next time.

If the sink rate is very poor, it might be effected somewhat by the spoileron configuration. The up trimmed ailerons are in fact spoilerons as well as they are simulating wash out.

Also keep in mind that they are simulated wash out only to the extent that the plane is kept fairly level. If roll axis is commanded that brings the aileron neutral to the wing, the simulated washout has temporarily disappeared leaving the wing possibly open to tip stalling.

I'm not sure whats going on with this plane so I'll just offer some suggestions to the owner to help improve the performance from where it is currently. It's important to keep in mind that the designer never intended the ailerons to be neutral at 1/4" above the trailing edge. Flying it like this drastically changes the flight characteristics so you'll want to get the plane configured the way it was intended as soon as possible.

If you know the manufacturer and have the CG location and suggested incidence setup for stab and wing verify they are in the range recommended and that the plane is not overweight. Check lateral balance. Check to see the wing is not warped or twisted as has already been suggested. (Folks on this thread can help you measure the incidence without any fancy tools btw).

Next, adjust the ailerons flush with the trailing edge and take off after building plenty of speed on a calm day. After attaining some altitude slow the plane down while feeding in up-elevator until you stall it. I suspect it will behave without drama as a normal plane but if it snaps you will know the slowest speed you can use to land it.

Land it and come back and tell us how it behaved and we can then continue with more testing and changes if necessary. Good luck.

The plane was designed and built by the previous owner. I have no list of control throws, only the throws on the plane. There are marks on the wing for trimming the ailerons, which show that the washout is included into the trim.

Sounds like you've figured it all out then. Enjoy your airplane.

I'm sorry, I never meant to sound like that.[] I have no idea of what I am doing.

All I know is that the plane was trimmed like this for a reason, and I don't want to put myself into a position where I won't be able to control it. Right now this is my only flyable plane, so if I lose it I won't be able to fly. I barely know how to land the plane now, how will I be able to land it even faster?

Having just gone through a rather hairy maiden myself I can empathize with that. Perhaps some explanation behind some of the comments floating around will help ease the nerves.

First, lets look at tip stall. Sometimes a wing shape with taper will begin to stall at the tips first because of the shorter chord and lower Reynolds number. The tips never stall in perfect unison so as one tip seperates the plane falls off to one side uncontrollably due to the lever arm distance between the tip and the CG of the plane. It usually happens at the slowest speed of a normal flight which is just before touchdown when there is no room to recover.

Most of the time designers will just opt for a lower wing load or less tapered wing shape but in the case of high aspect ratio gliders and scale powered planes like yours they're kinda stuck with it. Washout is an attempt to compensate for the tendency of the wing tip to stall at low speed. The wing is twisted from the root near the fuselage out to the wingtip so that at any attitude the root is always at a higher angle of attack than the tip. This guarantees the roots will stall before the tips at low speeds. When the roots stall you don't have the moment arm effect so the plane tends to fall straight forward, not to one side.

Now lets look at ailerons. Normally, when the pilot gives the plane "right aileron" the control surface on the left wing panel goes down at the trailing edge increasing the ability of that section to generate more lift (more camber). At the same time the control surface on the right wing panel deflects up at the trailing edge spoiling the local lift and decreasing the ability of that section to generate lift. When combined, the two panels create a strong torque about the fuselage and the plane rolls to the right.

Because both of your ailerons are currently deflected up when the sticks are neutral the wings are unable to generate as much "total lift" at any speed. In an attempt to prevent tip stall, the overall wing loading has been increased substantially. It's likely a third of the total wing area is generating very little lift which is causing the erratic behavior and difficulty controlling the plane at lower airspeeds.

So what can you expect by lowering the ailerons. The wing will be able to generate more lift at all speeds so you will actually be able to land slower. The tips are now "flying" however, so if the plane slows too much there may be a tendency to tip stall. That's why I suggested in my earlier post that you get the plane up high and try to stall it so you better understand it's personality.

Maybe you'll feel more comfortable with an incremental approach. Stall it at altitude with the ailerons in their current configuration. Crank them down about half way toward the trailing edge and try it again and so on. If the plane is found to have a nasty tip stall (which is totally hypothetical at this point) then we can help you put real washout into the wing rather than lift spoilers. Real washout will enable the tips to "fly" when you need them to land.

Cratecruncher... a very well written explanation.