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Larry,
See interspersed remarks below. Looking forward to more adjustment
info.
Grayhawk
In a message dated 2/19/2010 12:18:13 P.M. Central Standard Time,
LHenney@charter.net writes:
Grayhawk,
Always the deep
thinker. You are correct to note the roll error. However, after working
with several 320/ 360 series roll errors I contend to have a better fix.
The flap lowering drag thing is too inefficient, ugly, and fails to
address the root problem (imho). I believe wings are to make lift. By
contrast, flap lift in cruise flight adds only to unwanted twisting
moments....
The flap is part of the wing as designed until it goes lower than
being taken out of reflex - then it is a flap. There was one thing (only
one?) I did not check carefully whilst building - the lateral relationship
betwixt the outboard trailing edge (corner) of each fuselage fairing
to flap since I was depending on the moldings. If I remember correctly
(and post build), the left one was 1/2" higher than the right when the
aircraft was leveled laterally. Since the flap and aileron were built
so that their trailing edge was on a straight line from that fairing to the
wingtip TE when the wing was positioned on its jig, it is possible that left
wing heavy occurred because the faired flap is too high on the left wing
(or a little twist is built in). Thus, frequently the level flight
position is achieved by adjusting the flaps (left down a bit, right up a
bit) and cosmetically fixing the mismatch at the
fuselage with bondo (uh, micro). However, note that if one is
flying solo (assuming internal components have been placed so that the empty
weight is almost evenly split between the mains), the left wing needs slightly
more lift. For a reasonably weighted pilot and almost full wing tanks
(standard design), 4 gallons more in the right wing than the
left pretty much balances the aircraft around the centerline. Of
course, equal wing fuel and a similarly weighted right seat
occupant accomplishes the same. It is up to the builder on whether to
bias the wing lift for solo or dual flight - anyway, that is easily handled by
aileron trim. The flap adjustment is so minor as to not affect overall
flight characteristics other than remove the "heavy" wing component. Think
of it as less reflexed unlift.
We removed the trailing
spar attach strap. Then we offset the two outboard holes on a new strap
by 90 thousandths. After flying flight two today, the ailerons sit
perfectly flat with no roll component. There was no adjustment to the
flaps. They look good on the ramp (especially when you look at them
simultaneously!).
Clever!
Now the real
ponderance. Should I make both left and right new trailing edge straps
with 45 thousandths correction on each side? This of course
would minimize that finger nail thickness of body work
error.....
Regarding flap
reflex...... This is a vintage 1987 glacially slow build 320. I
remember a long time ago that you almost convinced me that my FB 360 circa
1996 had the fillets set to the 7 deg reflex. "almost" because
my manual still said to set them 5/8" high (or so). I thought you were
working the FB aspect. Are you saying ALL 320/ 360 vintage fillets are
molded correct to 7 deg reflex? So only the 235s were to be
reflexed? Could Lancair maybe mention this manual / blue print error in
a SB?
It is 7 degrees. The 235 fillets matched the unreflexed wing
design and the recommendation was to raise the flaps to -7 degrees when
over certain speeds (140 or 160 KIAS, I forget) because of the severe wing twist
if left in the 235 "faired" position. I am sure you feel the terrific
pitching moment when the flaps are moved. The 320 slow build fillets were
molded to the cruise position. My instructions did not contain anything
about adjusting them above the faired in position. I know you tested
performance by trying to reduce drag from lift at high speed by raising the
flaps higher than normal and you reported that no improvement resulted (of
course this was information passed to other competing racers and may have been,
uh, adjusted for their consumption). I tried the same and also found no
improvement and I am still willing to take on any NA 320 side-by-side regardless
of their flap position. It is true that if the flaps are adjusted to the fillet
at 0 KIAS, they will fly higher at >0 KIAS - easily checked by
hand lifting them and noting that they will be above the fillet.
Maybe the instructions you saw were to correct for badly molded
fillets.
But alas Mark and I
both concur that about 3 degrees vs. 7 is indeed faster. Anyway, yes
they are reflexed and surely they are supposed to be back in 1987, no?
Convince me.
Hmmmm, Are you saying that at rest they are another 3 degrees above the
fillet? At high speed cruise, say 180 KIAS or so, with the extra reflex,
what is the position of the elevator horns? Is it difficult to
trim nose down? What is the horizontal stab angle of incidence?
BTW, the VEP up pressure switch lasted 2.2
hours. Not bad from what I hear. Lucky to have a spare new style switch
in my parts bin. More data collection tomorrow.
Larry
Rick,
Congrats!
Uh, the 320 slow build kit contained at least 121,432 parts, not to
mention all the extra hardware obtained from Ace and various race shops.
It also consumed 19,123 sheets of sandpaper.
Comments:
The flaps are flying too high in pic # 1 and 2.
In all pix, the left aileron is below the wing tip fairing usually
indicating a heavy left wing (very common). Re-rigging the flaps can
help with the heavy wing condition.
Grayhawk
In a message dated 2/17/2010 1:39:41 P.M. Central Standard Time,
LHenney@charter.net writes:
Lancair
Friends,
Put your hands together
for Rick Cathriner's most excellent 1st Flight. N41LA Certification occurred
earlier today with a very complimentary "no squawks" report from his DAR
Dave Eby.
N41LA took to the sky's
today after a 22 year gestation. Lady's and Gentleman I suspect
we have a record. Airborne initial testing shows again, no gripes,
fast and true. Builds Slow, Flies Fast! Does anyone remember how many
pieces came in the original 320 slow build kit?!!!
Still wishing someone
would step up with a Riechal Trim system. Anyone, anyone?
Bueller? I think we'll reverse engineer one from a local 320
flyer......
Congratulations Rick on
a Job Well Done! To you builders out there, never give up! To
the flyers, meet Rick for lunch sometime. He's earned at least one
free trip to the Hard Eights BBQ in Stephenville
(SEP).
Way to Go
Rick!
Larry
Henney
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