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Bill,
I was just pulling your main gear leg. However, consider this:
Reflexed flap wings have a significant pitching moment. Note their
use in tailless airplanes where the "flap" completely controls the pitch.
Referring to only 200/300 Lancairs and specifically the 300 series, the flap in
reflex creates so much nose up pitch that the elevator is trimmed to
unload its negative lift as speed increases. As that negative
lift is reduced, so is induced drag reduced - thus the aircraft
becomes more efficient. If one looks at the horizontal as an upside down
wing, one might even say that thru a certain range of the elevator
unloading the tail puts the elevator in reflex.
At high speeds, the AOA of the main wing is siginificantly reduced to
maintain the same lift (unload the tail) and the reflexed flap may allow
the laminar flow to re-attach at the flap, further reducing drag.
Also, consider also that most canard pushers with air
cooled aircraft engines use updraft cooling that is inherently
inefficient as the cooling air passes over the exhaust pipes first (picking up
heat) and that its return to the slip stream suffers from the drag
induced by the aft openings of pushers.
Scott AKA Grayhawk
In a message dated 1/13/2013 1:29:22 A.M. Central Standard Time,
super_chipmunk@roadrunner.com writes:
Hi Scott-
I was exaggerating for effect- However, my understanding is that canards are
theoretically more efficient because the canard provides a lift component as
opposed to a horizontal stabilizer that has to create negative lift. In both
cases the aircraft is balanced so the nose drops during a stall. In practice,
the canard *has* to stall before the main wing. The “deep stall” experienced
during a flight test on the Velocity is a case in point. That plane entered a
stable vertical descent- I think it was 500 FPM- and couldn’t be gotten out of
it. The pilot actually opened the door and tried to shift CG by leaning
forward. Fortunately it landed in water and the pilot survived with back
injuries. The factory did some innovative testing to try to understand what
happened.
I had one of the first Velocity kits (a very early RG), and after
some time we received cuffs that we were told to put on the elevator LE. I
wasn’t thrilled- I already had everything built and carefully adjusted. I
never heard an explanation, just that it was to adjust the gap and decrease
the lift of the canard. From this, I’d speculate that during the incident the
main wing partially stalled while the canard kept flying. Under those
circumstances the nose couldn’t drop and the wing couldn’t regain lift. So the
fix was a compromise that reduced efficiency in return for an extra margin of
safety.
I never finished mine as I saw enough fatalities over the years and found
too many construction aspects that I didn’t like. In the end I decided the
plane was too limited in terms of fuel capacity and payload so I abandoned it.
My understanding is that as a stall approaches the canard stalls first due to
higher loading, dropping the nose and regaining airspeed. If the conditions
continued, the process would repeat. -Bill Wade
Sent: Saturday, January 12, 2013 4:36 PM
Subject: [LML] Re: Fw: [LML] Re: Purchase Advice
LNC2
Bill,
Recently there have been many canards on this list - Oh, maybe you meant
aircraft with canards. I challenge your statement that they are more
efficient. However, they do operate well in the ETE as long as the
canard remains clean as a smutty canard causes loss of lift on that crucial
wingy-thingy. Only Klaus has an efficient canard aircraft although you
may have to find out how much power he wrings out his engine and what that
funny skinny prop is doing. BTW, they are good airplanes that avoid main
wing stalls and just mush on down.
Grayhawk
In a message dated 1/12/2013 12:18:16 P.M. Central Standard Time,
super_chipmunk@roadrunner.com writes:
In this discussion I’m surprised that Canards haven’t been
mentioned. It’s well known they’re more efficient- surely that’s due to the
fact that they were designed from the ground up to fly backwards.
Also, given the fact that there’s a reversal of the Coriolis
effect between the two hemispheres why hasn’t there been a discussion of
ETE- Equitorial Transition Effect? That’s the warping of the space/time
continuum as you approach the Equator and then experience the reversal
during passage. This is distinct from ETA- Everyone’s Talking Australian, a
spatial and temporal dissonance caused by situations such as:
What’s a Goanna- is that what’s eating my Marmite (a cute, fuzzy
marsupial).
Is it polite to play your Didgeridoo in public or it only for
consenting adults?
You get the idea... Cheers- Bill Wade
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