Hi Andrew,
>What I often find confusing with the manual is that it says what to do, but
it doesn't say why. As a scientist,
> I hesitate to do something until I understand why.
I am the same way, and predict many other builders out there are as well. It
makes for a lot of thinking testing and preplanning before assembling. Many
times one can create better ways (than what is in the manual) to put this
thing together but it also eats up a lot of time. I find myself asking this
question often when starting up a new task...Whats more important, precision
or time? Most often, precision wins out. It is an airplane after all, and
one can't expect to 'pull over' up there in the big blue skyways. Oh well,
long precise build it is :) .
When building the module up, one needs to check for clearances between the
controls (plywood strengtheners, fuel lines, etc), and the bottom of the
fuselage ..many times. The bearings (or the flange lips) for the control
arms (or the lower side of the control arm bracket) can hit the bottom of
the fuselage. The manual tells you to get them as low as possible ..but they
can be too low. I also remember needing to grind the top layer glass and
PVC away from the bottom of the fuse. (and re-glass to add the strength
back) in the rear where the controls were binding, because they needed
another 1/8" (or so) clearance (Bud has seen this too, apparently ..notice
his reference to CS08). ...other things needed nips and tucks to get to fit
properly. A builder could easily miss these small clearance issues if they
are not careful, resulting in a lot of binding (and a bunch more unexpected
work) once the module is sucked up to the fuse while clecoe-ing or strapping
pre-gluing. During the process of populating the module with controls (and
stuff), I found it convenient to finalize the position of the module at an
early state. If that is not done, the module can slide around too much, and
it just makes it difficult to know where to do the nips and tucks to get
everything to work well together. I am sure you can wait until just before
bonding the cockpit module to the fuse before drilling the placement holes,
if you were very careful to realign it over and over again during the
clearance checks. I opted for aligning it just once in the beginning. There
are sure to be other methods, and possibly better ones out there....but this
one worked well.
The two holes were placed up front where the module would not deform over
time. It is very strong up in the front around the tunnel area. The lower
part of the tunnel was positively contacting the inside of the fuselage, so
the small bolts went through the forward, lower flange of the module and
through the firewall in that area. The top of the tunnel was not a good
candidate for the bolts, because there was a slight clearance between the
tunnel top and the firewall (other planes might be different?). Putting a
positioning bolt there would cause instability and straining on the module
and the firewall. Better to let the glue fill that in when the big day
arrives.
I hope that covered it a little better..
Greg Fuchs
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Andrew Sarangan
Sent: Wednesday, August 17, 2011 9:32 PM
Subject: Re: Europa-List: Trial fitting cockpit module
I think my question may have been misunderstood. I realize the importance of
CM alignment to the fuselage. My question is, isn't this alignment best done
after the control tubes and fuel tank are installed rather than on an empty
CM? I was thinking that some deformations to the CM may creep in during the
work, so drilling the alignment holes through the firewall may be best done
when the CM is nearly finished. Or, is the empty CM is significantly lighter
and hence easier to align?
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