Re: The difficulty of high-lift devices for tandem wing aircraft (long)


Arthur & Margaret <warreen@...>
 

Jeff,Great opportunities come to those who make the most of small ones.
Arthur

----- Original Message -----
From: "Jeff Quinn" <quinnj@...>
To: <Q-LIST@...>
Sent: Monday, November 07, 2005 1:25 PM
Subject: [Q-LIST] Re: The difficulty of high-lift devices for tandem wing
aircraft (long)



Well I got permission to access the q performance group and crossed
upon information about tri-foil concepts. Yeow, what a different
approach to trimming the lift machine. In my R/C past, flying
neutrally stable highly precise aerobatic planes which would always be
in trim as long as it was where the pilot left it, the concept of
center of pressure vs. center of lift became a big deal.

Anynow, the cp of the Q2 is a ways back from the CG and the resultant
inefficient loading of the rear wing vs. the canard becomes an induced
drag vice compared to an optimized conventional craft. My crazy mind
began wondering about installing a trimming device atop the vertical
stabilizer of a Q2 and reducing the front incidence angle on the canard.

Long story short, I tried this on a tandem wing freeflight model. The
result is that both the canard flaps as well as the former ailerons on
the main wing can be deflected down to serve as flaps, trim being
maintained by the T tail horizontal stab. The model flies slower and
can take a further aft CG with this (very small) added flying surface.

Question becomes, is the parasitic drag of the tiny horizontal
stabilizer less than the induced drag of a trimmed canard system?
Barnaby Wainfan of Kitplanes wrote an excellent article on this subject
some years ago, conclusion being the so called drag advantage of canard
platforms (trimming surface lifts rather than applies weight) erodes
due to the induced drag disadvatage of having one wing always stall
well before the other.

The tri-foil concept removes the canard induced drag vice , but how
would it work on a tandem wing, rather than traditional Buck Roders
style canard? Piaggio knows the answer to the latter, perhaps I should
pursue the answer to the former........ muahahahahaha
--- In Q-LIST@..., "Peter Harris" <peterjfharris@b...>
wrote:

Unfortunately it takes a quantum leap to move from concept to
application. >
Peter
----- Original Message -----






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