I have this theory that I haven't put a lot of thought into because it's mind-boggling. It comes down to all that P-Factor/prop wash stuff.

I'm thinking that due to the unequal effects that the prop blast sends over the wing and flying surfaces that the aircraft should not be exactly symmetrical. In what way I don't know, but for example, maybe the wing needs to be canted somewhat. In other words, the left wing tip may need to be a small degree behind the right wing tip.

I'm curious if anyone knows of any studies conducted on this and if there's any validity to my theory.

CafeenMan,

In principle, probably not. The fact that the prop constantly exerts a rolling torque on the airframe means that, in principle, you should have some compensation. In fact, you do. When you first fly your plane, you trim the ailerons, and that pretty well takes care of it. It probably makes more sense to take care of the torque this way than by trying to build a correction into the wings.

There are other asymmetries. The prop exerts torque on the airframe in a few other ways. Probably the main one is yaw as a result of propwash impinging on a vertical stabilizer that is not symmetric above and below the thrust line. This is most noticeable during takeoff, and can be minimized by balancing the vertical stabilizer above and below the thrust line. The gyroscopic forces due to the prop ( & other spinning mass ) and the 'P-factor' are also present, but probably negligible.

Overall, I think that trimming, and a few expediencies like adjusting the thrust angle of the engine on some planes, are adequate solutions to the inherent asymmetries.

banktoturn

Cafeenman,
Take a look here -

http://www.nurflugel.com/Nurflugel/n_o_d/index2.htm

All manner of ideas....

banktoturn - I agree that for all practical purposes that building a straight aircraft that is symmetrical in all respects (with thrust adjustments) is the way to go. In other words, when it comes time to actually build a model, I agree 100% with what you said.

However, I was asking from a strictly theoretical standpoint. I don't think any model manufacturer has the means or the research staff to do what I'm asking about so it's really a moot point. It's just something I'm curious about.

probligo - I'll check out that link. Thanks.

I didn't read probligo's link material but you may be interested to know that full sized prop planes often have some offset built into the vertical tail just for this reason.

It's been a while since I looked at this stuff so I can't tell you which direction the tail is offset but I believe it was a little right.

CafeenMan,

I understand what you mean. If it came to building a nonsymmetric airframe to compensate for the nonsymmetric effects of the prop, I suspect that you could only have 'neutral' behavior for a narrow range of operating conditions ( airspeed, engine speed, etc ). If you wanted to get that theoretically perfect neutral behavior from a prop plane, you might have to do something more fundamental, like counter-rotating props, or a twin with different directions of rotation.

banktoturn

Prop go right, fin go left...
.
Amusing anecdote about an RAF type shot down in a MkV Spit.... captured and escaped, and returned to his unit, which had switch to the MkIX... opposite rotation Merlin. On his orientation flight..the takeoff rudder trim for the MkV didn't work well!
An abrupt right turn and takeoff between a couple of hangars ensued

Cafeenman,
one of Burt Rutan's later designs is laid-out along the lines you are considering. Wish I could tell you where to go to get the low-down, but don't have a thing on file. Remember reading an article on it , but it made my head hurt, so I didn't clip it.
Rutan has become a quasi-recluse so good luck getting specifics. If you do find the specs, I think you'll the prject interesting.

ddubya

ddubya - You wouldn't have his home address would you? I could just go kick his door in and hold a tube of Ambroid under his nose until he explained it to me.

Good luck with that, cafeenman! Seriously, you might try checking-out the EAA, that is SPORT AVIATION., also, AIR PROGRESS. I doubt it was FLYING but could possibly be.
ddubya

Cafeenman,

after a half dozen beers and a platter of nachos, a friend and I managed to remember the name of Rutan's design....drum roll please. It's the Boomarang. We didn't have enough nachos to remember where the article ran. You are on your own.

ddubya

LOL... thanks ddubya. I guess I'll have to make the effort to type "rutan AND boomerang" into the google window. Oh the burdens I have to bear.... <heavy sigh>

And the instrument panel is juat a shelf that folds down to hold a laptop that becomes a glass (plastic?) cockpit display... That guy is just too smart. You look at the Boomerang and think he's just showing off, but then everything starts to make sense...

http://www.popularmechanics.com/scie...ng/index.phtml

I've seen it at Oshokosh, very cool plane!