ORIGINAL: BaldEagel
Two theories have been banded about on this:
1. High speed air under the tail???? Benoli's
2. Semi semetrical airfoil section increases lift at faster speed, therefore downthrust needed to counteract.
Don't ask me, I have no down thrust on my Falcon 120, or on the Boomerang Sprint and never did on the Elan, but everyone told me I needed downthrust??? Mick Reeves Reapear and my C-ARF Rookies did not need any thrust adjustment either, the one thing all of these have in common is no thrust tube and a turbine stuck on the back of the fus, the other thing they have in common is a rearward C of G, because that's how I like it.
Mike
Don't like popcorn can I have some peanuts. LOL
I should have said
Wing Semi Semetrical airfoil section, as the speed increases so does the lift, those that have a pronounced SS airfoil Like the Falcon 120 need a lot of downthurst to compensate, the Boomerang range do not have a pronounced SS airfoil in conparason, therefore need less compensation, combine all this with the high speed air passing under the tail and we have a pitch up, Look how close the tailplane is to the efflux on the Falcon and others that need the up thrust and how far away the tail is in comparison on the Boomers
Mike