I put some side force generators at about half span on my E-Flite Tribute and it seems to have made the roll couple with rudder even worse.

They're 2" high top and bottom, and go from L.E. to T.E. (actually they end at the ail. hinge line )

What do you guys think of maybe making the top one taller than the bottom one, or vice-versa?

You got any theory or idea(s) as to the changes in the center of pressure or center of lift along the length of the fuse. while in knife edge flight? And what changes do SFG's make?

Where would you put the SFG's span wise on the wing?
How about the shape and height...and top vs. bottom area wise?

I have a lot of questions and ideas...but not a lot of real knowlege about aerodynamics...I just like to experiment, but I'd like to know the reasons why things happen when I make a modification, ya know?



Back in the mid 70's I made an airplane (original design ) that had huge tip plates on it, because I liked to do knife edge the length of the runway. The plane was a (K&B) .40 sized what would now be called "fun fly" type w/ a Sullivan PDQ foam wing clipped to 42" and a fuselage that was of the absolute minimal size vertically and of width.
It had a flat top, kind of like a Kaos, but I put what I called a "knife edge ledge" all along the length of the top that was a 1/4" lip that acted like a chine to hold the air on the side of the fuse. while in K.E.

The H9 Showtime brought back memories, and spurred me on to adding SFG's to the Tribute, and seeing the G.P. Turmoil, with it's design of SFG's, I'm wondering what you guys might have to say about the subject...



Thanks...Tom

Its the tribute a T-Tail? It might be happier if it were, though the best small planes arent very stable. Another option might be canards but they have a very dramatic effect on the pitch rate of the airplane.

SFG mods do work - I had a Tribute and have a Tensor and a Showtime .
Ideally-- the plates simply add area at the CG you are using
IF--you add area forward the cg, the response in knife ege will become more sensitive.
When we did pattern models , it became obvious very quickly, lateral area placement changed knife edge flight.
The further forward the average of lateral area, the more balanced the lift in knife edge.
This must be weighed against stability in yaw .
The SFG additions are very high in drag-for the additional lift they add, but in foamies the loadings are extremely low and the angles of attack in knife edge are very low -so if you simply roll to knife -add no rudder - they can be setup to fly almost as flat as in level upright flight.
The Tensor turns with rudder -NOT from banking and adding elevator as many would assume.
Bank the plane --it just remains on heading-with wings tilted. Very strange visual.
just make up some plates and try em on the Tribute - the tail moment is way too long for my tastes so make the SFG's slant forward (try to ingrease lateral area forward.)
Ideally a simple increase of fuselage lateral area -forward -works better . more lift for far less drag induced.
This isn't from formulas -it is from flying em.

Thanks Dick...
The Tribute will pivot on a wing tip during a hard rudder turn...but I need to feed in substantial opposite aileron to keep it from flipping right over in sort of a snap.

Think I'm gonna remove either the top or bottom SFG's (one at a time ) to see what happens.
I'll let you know.

I had a Tipo for a little while, in the early 80's, so I know what you mean there

Hi Proptop

That extra ability to yaw may be so powerful you are stalling the inboard wing when you apply high rudder deflection. It still definitely worth experimenting a bit with moving the location or geometry of the SFG's though, as Dick suggests.

I think that's exactly what's happening DT
I flew it again last night (got a great, well lit parking lot ) and noticed that myself...
The SFG's certainly make for some interesting flight characteristics!