valleyk

I have a BUSA 1/3 Pup and setup the wing incidences. I wanted to keep both wings at 1 degree positive incidence. The top wing came in good with rigging and struts uniform wing incidence of + 1 degree no twist. However the bottom wing has a twist on both sides of fuselage. The twist is symmetric on both sides and goes from zero incidence from fuselage to + 1 incidence to wing tip. Should I be concerned?

BobH

My Feedback: (2)

Seems as if you have a bit of wash in on the wing tips for what ever reason. Being that slight I don't think it'll be a problem. These WWI plans have lots of lift, you should be ok. Be prepared to put in some down trim during flight, you might need it.

vertical grimmace

My Feedback: (1)

Sounds like the wing saddle needs to be shimmed down at the trailing edge. Should not be an issue though. WW1 planes are so dirty, and it seems you fly them all the time even when trimmed out. If it makes you more comfortable, add 1/8" to the saddle at the trailing edge and re-check. That should get you close. Wash out is better than wash in.

valleyk

I got this plane built and the workmanship was not good. I had to strengthen wing with rib doublers and spars. The lower wings have a built in twist to them as described and I think a repair will just twist the upper wings. I'm in a corner and a hard place.....maybe I could live with it. So far no one seems to feel differently.

abufletcher

It seems to me that on such a large model, you can pretty much do everything with rigging. The angle of attach at the root is set by the saddle. But you should be able to adjust the outboard incidence with the strut cross-bracing wires.

valleyk

Again Abu you are right but vertical's approach makes sense to fix incidence at saddle but Ican't. Its a tongue and groove bonded to fuse connection and I'm stuck with that incidence. If i use the rigging cables to correct the best Icould do is have the lower wing at zero incidence no twist and upper wing +1 degree incidence no twist. I'd rather just leave it.

vertical grimmace

My Feedback: (1)

I think that it is almost always possible to add material or remove it. Especially before something is finished. If a tounge exists at the leading edge, maybe material can be removed here to lower the incidence. Once the root is squared away, Like Abu says, the tips can be adjusted with the interplane struts. The root must be corrected first.

abufletcher

If there's one lesson above all others that I've learned from RC building is that ANYTHING CAN BE DECONSTRUCTED! Razor saws and dremel tools are particularly helpful in this regard. Seriously, I've rebuilt the tongue and groove on my Puppeteer at least a half dozen times.

jeffo

My Feedback: (68)

Val,I'd give Dave Lewis a call at BUSA,He is a very knowledgeable and speaks in clear english.I know you don't want both wings at the same angle,if I were to guess on the set up
bottom wing 0*
top wing 1* pos.
stab 2* pos
Best to talk to dave
good luck jeffo

Steve Percifield

My Feedback: (14)

This is apparently a modification of the original kit. The original's wings are held on by the wires. There is no tongue and socket for neither wing, simply alignment pegs. The wires then hold the wings on. So maybe some error was built into the tongue assembly. But, honestly, 1 degree off isn't enough to make any difference. I've had 2 of these and assembled them at the field, tightened the wires and flew. I never measured incidence after the initial build setup.

If the wing is actually twisted, try taking the twist out by twisting in the oposite direction and shrinking the covering with a heat gun.

You should check a manual. I can't remember, but the numbers you quote don't seem what the manual says either.

JMO
steve

R/C Art

My Feedback: (38)

from what i am reading about your plane, without rebuilding something, what you have here is the best you can do.......I would go with this.

Either way, your pup will fly fine. The warps are equal and therefore will not require any trimming in flight to correct.

Here is my take on rigging the 1/3 pup......as per the kit instructions the wings are set at zero degrees relative to the stab - this is measured with a straight edge held under the bottom of the wing......and the stab is zero degrees. This flys fine but wiill require down trim to fly and the engine needs down thrust.

The rib has a raised leading edge and an unchambered air foil and when the kit settings are measured with a Robart incidence meter it show +3/4 of a degree.
I know because on my last pup build I checked and measured these items. With the meter I set my wings at 0 degrees and left the stab at 0 degrees, put in noticeable down thrust (I didn't measure) and, after playing with the center of gravity a little bit, the plane flew great. The elevator flew with no trim and the plane did not balloon (climb) when power was added.

Your pup set up like you when you received it, or adjusted to take out the twist in the bottom wing will fly the same. And like the first comment above, be ready to add some down trim.

Its just not as critical as most folks want to make it out to be. Once you get it flying, there is always trimming and adjusting of the flying surfaces and CG to fine tune the plane to your liking. Fly it first before you go off lthe deep end and do major reconstruction.

That's my two cents worth........Art

Tmoth4

My Feedback: (1)

I think I would set the lower wings at zero all the way accross. You can do that with the rigging, and leave the upper wings at the 1 degree positive. You'll have the upper wing stalling first when landing, which is a good thing. The plane should fly fine. Like Art suggests, a little down thrust (maybe 1 degree?) wouldn't hurt.

It seems every time I put one of my WW1 models together at the field they trim out different on the first flight. It's just the nature of them. And small incidence discrepencies don't seem to affect WW1 models like they would a WW2 type plane. The first flight of the day is always a trim flight!

Jim

vertical grimmace

My Feedback: (1)

"Here is my take on rigging the 1/3 pup......as per the kit instructions the wings are set at zero degrees relative to the stab - this is measured with a straight edge held under the bottom of the wing......and the stab is zero degrees. This flys fine but wiill require down trim to fly and the engine needs down thrust."

This is one of the problems with the BUSA kits instructions. This technique does not result in zero incidence. The measurement needs to be taken through the center of the airfoil, not simply throwing a straight edge on the bottom of the wing. The datum line of the airfoil passes through the center of the Leading edge. This is why so many of these models require down elevator.

That being said, it is no big deal having to carry down elevater, some would just prefer to have the it flat relative to the stab when sitting on the ground. My triplane carried quite a bit. Probably around a 1/4".


Valley, nice to hear you are plugging away on the pup. You will have to come up to love air and fly with me sometime.

gabriel voisin

"If the wing is actually twisted, try taking the twist out by twisting in the opposite direction and shrinking the covering with a heat gun."

I agree with Steve, that's the only right way,...even with dope it works.


Matz

ARUP

Raise the lower ailerons.

valleyk

Really good advice here. I’m in agreement with Vertical that Busa plans are little confusing on how to set up wing incidence with stabilizer. I don’t have the plans and don’t want to purchase them. I don’t think this is rocket science to set up incidence and I have done this on my GTM Fokker with success. I first place a level on the fuselage and zero it out so level. Then place wing incidence meter on wings and measure it…simple as that. I plan to do the same for the stabilizer, place meter on it and give some positive incidence with engine down thrust of 2 degrees (see pic). As far as the winner is concerned I’m going with Tim and RC/art to get the twist out on lower wing making it zero incidence and keep the top wing at +1 incidence.

Interesting little find on the net. Found authentic Sopwith Camel drawings. Get this it say’s. The angle of incidence of the top plane is 2 deg. at the center section, 3 deg. at tip. The botom plane has uniform angle of incidence of 3 deg. The tail plane, which is deeply cambered on both sides, is rigidly attached to the upper body longerons, with and angle of incidence of 1.5 deg. (I assume the incidence is measured from leveling out the fuselage…who knows)

Thanks again for the advice