In a message dated 9/23/2004 8:59:35 AM Central Standard Time,
MikeEasley@aol.com writes:
Why am I bringing this up in a discussion about stalls? I think
this kind of stuff will affect how a specific plane behaves in a stall.
One guy has very symmetrical wings and he breaks straight ahead, another guy
has some uneven twist and he gets a significant wing
drop.
Mike,
This is why I believe each hand built Lancair is different.
On my slow-built 320:
1. While the wing jigs were very carefully and exactly positioned,
one point was not verified. The trailing edge of the fuselage wing fillet
was later found to be different by 1/2" (from lateral level) from one side
to the other. Thus the flap construction and the chord line differ
slightly from side to side with some builders seeing a "heavy" wing. This
can be altered by rigging the cruise flaps to account for this. If
there was any variance in the angle of setting the stub wing flap bell cranks
(differing from 63 degrees, off in tilt, etc?), the extension flap travel may
differ from side to side. Thus the airplane may stall differently with
flaps retracted or at any extension position (-7 thru 45 degrees) because
of roll tendencies. If I remember correctly, Mark Ravinski adjusted the
flap rigging on his 360 to make it behave better in stalls. I think
some builders spotted this problem during construction and adjusted the
fillets before completing the flaps and ailerons. I know that
when I slooow down in the pattern with flaps at about 15 degrees and rudder
trim adjusted, I should re-trim the ailerons.
2. The next time a gaggle of 320/360s are sitting around, go stand at the
prop spinner of each and, using both eyes, look at the top of the vertical
stabilizer. When I last did that some years ago, about 50% are like mine,
slightly twisted. After all, in some cases I believed the molded part was
"accurate" (well, I was a tyro). I must do a survey and relate this to
slow or fast built. I don't know how much this twist affects stall/spin
recovery. There is evidence of differences by the way people have
described rudder trim management at cruise and slow speeds. Please
remember that, like most builders, I am an "untrained" test pilot. I do
read a lot though.
Then, are you sure the "ball" instrument is orthogonal to the aircraft
axes?
Scott Krueger
AKA Grayhawk
N92EX IO320 Aurora, IL (KARR)
Some Assembly Required
Using Common Hand Tools.