I just built a SPAD. I read that the ailerons should be set so that when you look at the model from the side the ailerons are parallel to the same axis as the horizontal stab. Since my wing has a 2 deg angle of incidence, when set this way the ailerons on both sides jut up somewhat unnaturally compared to the trailing edge of the wing. What are the reasons for this? And since the ailerons are aft of the C of G would this not cause the aircraft to want to climb (like an up elevator setting)?

Also I have some down thrust on my model, about 2-3 deg. The model flies well at all speeds but wants to stay inverted when I roll inverted. All my previous models would loop for the ground when rolled inverted.

Could the Aileron setting and down thrust somehow be adjusted to compliment each other?

Thanks.

Hi Spad , Where did you read about ail; being parallel with stab? I always put ail; so that when i look at the wing from the tip it looks like a continuation of the airfoil section . Some WW1 planes have a 2-3 degree positive on the stab so that would look weird if ail; set the same . Why not put ail; as i suggest & try flying it again . 2 degrees down sounds right & i usually have 2 degrees right also .

I got the "critical" info from "SPADtothebone.com". plans-trainers-debonair-page30-note3.

It has led to better flying charicteritics in the past with other SPAD's. Does anyone know why?

I have a foamie combat plane that does this with the ailerons. I think delta wing planes (without a separate tail feathers) reflex the ailerons in the same way. My guess is, if it has a really short tail, it may need some "up" aileron to get the nose up. Otherwise you might run out of up elevator in some situations.


Carl

With a regular model this "reflex" just makes the lifting airfoil a bit less lift'y. It's not that critical at all as long as they are even but if you droop them so the upper surface is one long smooth curve then it's the same as putting in a lot of positive wing incidence and that would give you problems in that you would need a bucket load of down trim to make up for that. Just keep them so they are close to level near where the designer intended. It doesn't have to be dead nutz level with the stab but it should be close to level in your case apparently.

As for downthrust you just use what you need. There's no magic formula where the angle is keyed to any other angle.

Now as for the lack of down trim needed for inverted that IS odd. If it flies basically hands off and level both upright as well as inverted then that tells me that your CG is as far back as it should be or that the combination of reflex and downthrust has produced a magic mixture for you. The aileron reflex in combination with the airfoil is acting like a symetrical airfoil apparently. Just another example of SPAD magic I guess.

I have done some experimenting with aileron settings by using a computer radio with the ailerons set up as flaperons; i.e. you can trim in any amount of up or down on the ailerons simultaneously with the flap control yet have normal aileron control. Yes, minor changes can make a big difference in how the plane flys. You can usually find a sweet spot where performance is as you like it. I set it up so that, with change in throttle setting, little change in altitude--just increase or decrease in speed--and there is usually a spot where the trim doesn't need changing to fly level wether you are inverted or right side up. If you have a computer radio and two servos on the ailerons, it is an interesting experiment.

Having flown the same spad, the purpose is to stop the deadly tuck under when to much speed is attained. Acts like elevons at high speed to keep the nose up. CG is back far enough on mine to cause it to climb inverted. These planes are set up to fly slow and do 3d stuff. They do get out of shape, literally, at high speed. You can see the wing bending and the tail twisting.

I read all of this and then realized the topic was/ was not the WW1 fighter-
Time warp----

Hi Dick, I was the 1st one to reply to this site & like you being a scale flyer thought it was the WW1 spad . Hurri

um, Simple Plastic Airplane Design (SPAD) Sorry for the confusion fellas. But thanks for the input folks, it all makes a bit more sense now. i have experienced the deadly tuck with coro/ gutterpipe machines. The aileron setting smoothed that out.