CubMan1950

i recently purchased a used, but with only a few flights, Tiger Moth. I took it out of the maiden and it floats and floats. I am in the process of checking the incidence, without a manual, and I have come up with the following results. The horizontal reads 1 degree, the lower wing reads 3 degrees and the upper wing reads 4 degrees. I have no manual for this aircraft and after researching the web, I am more confused. This guy says 0-0-0, that guy says 4 all around and I even had one say something like, 1.2 neg on the upper wing and 3.o on the lower wing. Does anyone have the proper settings or is there a formula to make this happen right. BTW, it's a 54 inch fus and a 72 inch wings.

UStik

No practical experience with biplanes here, just "theoretical":

That looks like an "original" setup, at least similar, see here. The TM was a floater, the Wikipedia article says "parachute wings" (here), its 130 hp was not exuberant.

I think big wing incidence is meant for cruise flight, after all it was a trainer in the first instance and not an aerobat. The big wings produce quite a downwash, so the stab has positive incidence lest there's too much decalage.

For best efficiency, one would make the lower wing's incidence bigger (because it's in the upper wing's downwash). The opposite (like here) is often done to aerobats, which would not have that big incidence (see here), though.

I don't know any hard rules, it depends on your intentions. That leaves us with the question what the designer and/or builder of your model thought.

UStik 1951

Rodney

I have found that all the bipes I've had (some dozen or more) all fly best when the upper wing is about 1.5 to 3 degrees less angle of attact than the lower wing is.

All Day Dan

My Feedback: (5)

Cub, I use 0-0-0 and am very satisfied with it. You can't go wrong with it. Dan.

CubMan1950

Thanks for all the input guys, I changed the top wing to 2 degrees tonight. Gonna have to wait for better weather to test her out, hopefully this Friday. I'm a fairly new pilot, 2 1/2 years, but the guys at the field say I'm a fast learner and I've had some great mentors. Lets all pass our knowledge forward to the youth.

RAPPTOR

My Feedback: (41)

+1

BMatthews

0-0-0 is more what you want on a seriously hot aerobatic setup. Something the TM most certainly isn't.

On a model with positive stagger such as the TM has it's normal to rig the upper wing to be slightly less positive an angle than the lower wing. So I think you're going the right way. The gain is mostly in avoiding the upper wing stalling first and the high amount of drag pulling the nose up to a deeper stall of the overall airframe.

If the model is very "floaty" I'd think that is due more to a super light wing loading than anything else. And if it's that light and if it's over powered with a glow engine you might be having an issue with the power at idle being too much and it just wants to keep flying. If it's electric this isn't a factor of course.

Bax

My Feedback: (11)

Yep, BMatthews is right. Float, float, float is all in the pilot's control, and not in the setup of the incidences and decalage. A lightly-loaded model will need to be well slowed on final approach to prevent floating. The float is a result of too much airspeed. If your airplane is particularly light, and the engine's power at idle is high enough, then the plane just won't slow enough for good landings. It all needs to be checked out. Then you fly, fly, fly and practice those approaches and landings. It's all too common for RC pilots to land too fast.