I am building a Great Planes Super Stearman and having trouble with slaving the top wing ailerons. I have located the control horns as shown in the construction manual. With the push rod installed I cannot get the recommended throws. Has anyone else ran into this problem? Is the manual wrong?. With the push rod removed I can move all four ailerons up and down much more than the recommended throws, so the ailerons themselves are ok. But when I connect the push rod between the lower and upper aileron and try to move the lower aileron up and down I only get less than a half inch. of throw. I am using two servos in bottom wing only and slaving the top ailerons.[] Can anyone help?

Thanks
j3cubflyer

It's a matter of mechanics (linkages). The arm is actually a line from the aileron hinge line to the pivot point on the control horns of the slave link. The motion between the upper and lower ailerons is not equal. If you've done any mechanical drawing, you can sketch the action.

Regards,
DrGO

That's correct. It's a geometry issue. We've flown one now with top wing throws nowhere near the recommendations, and you can't tell the difference one bit between it and one with perfect throws. I wouldn't sweat the issue--just get it set up as close as possible with good slop-free connections, and you will be good to go. The plane flies great and you should love it!

The other way people seem to be getting around this is to use four servos...probably what I would do if/when I build this airplane, but not necessary from a torque perspective to be sure.

As per R/C Report, page #60, first column. Move the control horn on the upper aileron back until the mounting base was 7/8 " from the trailing edge. This eliminated the binding and it flew great.

There have been many comments about the aileron binding problem on the GP Super Stearman being caused by "geometry" but nobody has identified what the specific problem is. The problem relates to the location of the pivot points for the aileron connecting link. To achieve ideal geometry these pivot points would have to meet two conditions: 1) Both pivot points are the same distance from the hinge line. 2) Both pivot points are on the aileron chord line (inside the aileron!). A modeler could probably achieve the second condition with a little ingenuity, but there is a practical (non-ideal) solution. Note that the manual has you cut the aileron control horn between the second and third hole and attach the clevis to the second hole. This places the pivot points too far from the aileron. Instead cut the control to leave only about 5/16" of the lever arm. Drill a new hole as close to the control horn base as possible while leaving sufficient clearance for the clevis. Mount the control horns equi-distant from the hinge lines. There will still be some slight difference in throw between the upper and lower aileron, but the difference will be minimal and the ailerons won't bind.

Removed duplicate entry

Was this ever resolved? what did you wind up doing? I have the same problem and inquiring minds want to know. from what I see, disreguard the plans and do something else all together. why hasn't there been a plan change?

If you build the Great Planes Stearman ARF per the instructions, the upper ailerons will have different throw than the bottom ones. It does not affect how the model flies by any noticeable amount. Set the throws at the bottom ailerons and let the top ones take care of themselves.

i understand the different throws but does it matter if the book says 1.25" on the upper and 1.0" on the lower and my actuals are 1.25" on the upper and .5" on the lower?
.

Reference page #17, Step #4....Change the distance from 1 3/8" to 7/8" this will correct the binding problem & the difference to a minimum. AS PER R/C Report's review..

actually I did that with no real improvement. hence the first set of holes in the aileron. there is no real binding problem. the link arm at the upper horn straightens out and therefore won't push the lower aileron any lower. I don't know if I am overreacting and it will fly just fine or what. I should just put 4 servos in and forget it but it won't be scale like I want it to be.

stuffer i have one and never measured any throws i never do she flys perfect. just make sure they dont bind and lock full left or right.

I'm not directly worried about throws other than the differential in the upper verses the lower. maybe it doesn't matter. I don't know. I just know its not like the book says and this is my first bi plane. (being a full size aircraft mech doesn't help all this!) I live by the book and this is the first time I haven't been able to make something match the specs called out for.

where is this RC report?

R/C Report is a magazine that doesnot pull any punches...if it is good, they will tell you...If something is bad they will tell you why.....it is a great magazine
The review appeared in the June 2004 edition.

Codimasta
AMA 11269

TRY: www.rcreport.ws

I built my Stearman exactly per the manual. The planes flies fantastic. Very smooth. Don't worry about the maximum throw on the lower ailerons. You'll never need that much. Mine does beautiful slow axial rolls on low rates. About 1/2" on lowers.

You'll notice that the upper ailerons are half the size of the lowers. The factory set-up gives you twice the throw on the upper ailerons than you have on the lowers to compensate.

Just measure horn locations and assemble as per the manual and your plane will fly great!

If you notice on page 7 step 5 of the manul, it states to leave a very small gap between the leading edge of the aileron and the wing. Without this gap there could be a binding issue. Did you leave that small gap? Just enough to slip a piece of paper through!

Regards,
John

thanks to all for the information provided. it was the reinforcement I needed. I finished mounting the new G-26 last night and moving on to the cowl and false radial. should have it done by next weekend. could be this weekend but don't want to rush.