Dear Collective Wisdom-
I'm about to attach the lift pin sockets to my Classic (with MTOW mod) and
have a couple of questions:
1. The manual states that you may need plywood shims under the W26 & W27
sockets. The gap between the fuselage side and the sockets are about 12 mm
with the greatest one 14 mm. This seems excessive, but that's what they
measure. Is this normal? Also, the manual doesn't mention it, but I assume
that you have to grind a relief in the root rib flange to allow insertion
of the pip pin.
2. The washout of the two wings differs! (with my meticulous--read SLOW--
building, I can't figure how this happened!!!). The 70% span starboard wing
incidence measures 1.4 deg. when the root is at 2.5 deg. Not bad! But when
the port wing 70% span section is set for 1.5 deg. its root incidence is 2.1
deg. Much less twist. So, I programmed an Excel spreadsheet to sum the
sectional lifts and moments at 1 ft. intervals, and diddled the incidence
until
the lift moments of the two wings balanced. The best result is when the
stbd.
wing is set for 2.55 deg. at the root, which gives 1.45 deg. at 70%, and the
port wing root at 2.1 deg., which gives 1.5 deg. at 70% span. The sums of
the lift-moments are exactly equal with this setup. Any comments pro or
con?
3. Now, the tough problem--it is REALLY hard getting the spar pins in! I had
easy pin insertion before converting to the MTOW 1/2" pins and bushings. I
very carefully transferred the geometry to the new bushings, using 1/2"
bolts
to cast in place the new bushings using the old bushings as jigs. The two
wings
alone allow easy pin insertion. When I insert the port wing alone, the pins
slide
in with no problem. I then slide in the stbd. wing and the port pin--no
problem. Then, the stbd. pip pin gives me fits getting it in, even with
grease,
etc. I can barely get it inserted, but the pin will barely rotate once it
is in. Way too tight! I'm afraid that I will never be able to rig the
wings
once all of the lift pins, flap pins, etc. are in place. I believe that the
bushing spacing must be off by a half mm or so in the stbd. wing.
I have pondered on this, and have come to the conclusion that I will have to
either remove the stbd. bushings in the wing and try recasting them in situ.
Or, another scheme would be to assemble the wings, substituting a 1/2" OD
tube for
the pip pin, brute force into into place, and insert a heating element
inside to
soften the Redux in the stbd. wing bushes, allowing some time to relieve
stresses,
i.e. to have the Redux flow or creep slightly. This seems like it might
work.
What do you think?
Thanks for any suggestions!
Pops
A036
-----Original Message-----
From: forum-owner@europaclub.org.uk
Subject: Re: Wing angle of incidence
Cleve,
Yes, unless for some reason the bushings that you glued into the module are
very out of line. Which would be hard to do. The bushings allow for at
least the required amount of play to get the 2.5 degree angle of Incidence.
Bill McClellan
A164
----- Original Message -----
From: <clevelee@cswebmail.com>
Subject: Wing angle of incidence
> Collective Wisdom,
>
> I'm about to go about setting the wing incidence. I am puzzled by an
aspect of
> the mechanics.
>
> The pin busings that were bonded into the cockpit module did not have a
specific
> wing angle of incidence associated with the installation.
>
> Does it really work, that with those bushings already bonded in place, I
can
> expect to rotate the wing spar relative to the outside of the fuselage to
obtain
> the 2 1/2 degrees incidence, and still expect the pin passing through the
> cockpit bushing to slide smoothly into the spar bushings?
>
> What am I not realizing?
>
> Thanks,
>
> Cleve Lee
> Mono XS A198 N396ST
> Detroit, MI
>
>
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