Re: REFLECTOR: Aluminum Instrument Panel

[mhadley1@juno.com (Martin A Hadley)]

On Thu, 17 Sep 1998 14:10:21 +0900 Eung Tai Kim <eungkim@kari.re.kr>
writes:

>Is there any special reason that an aluminum panel is not recommended?

>All the certified airplane uses aluminum panel and the aluminum panel 
>is easy for the ground.

I will pass on a few reasons why I would not consider using aluminum for
an instrument panel in a Velocity.

Flexibility...while this may seem like an undesirable property, in the
event of an accident, I would rather accidentally hit my head on
something that is likely to give a little. Something that might absorb
some of the shock. 

Weight...weigh a Velocity molded fiberglass panel (approx. .100+ 
thickness) and a piece of .090 aluminum with the same surface area. While
weight and balance seems to always dictate the need for  weight in the
nose of a Velocity, anything that adds to the empty gross takes away from
the useful load! 

Ease of working...Scratch or incorrectly drill a new aluminum panel and
it time to start over , make a big compromise, or spend a lot of time and
effort welding and finishing a patch. With fiberglass, scratches and
patches are done in no time. Professionally, an Aluminum panel takes me
about 4 to 6 hours more to complete over a comparable fiberglass panel.
Layout, cutting, getting ready to paint, precautions while handling
aluminum all consume more time.

Cosmetic...a molded, canted fiberglass panel is far better looking than a
flat panel any day in my book!

As far as the comment about grounding, the only thing that should be
grounded on an instrument panel itself is the post lights for the
instruments. Radios, flight instruments, none of these should be grounded
to the instrument panel itself. I have not seen any of the production
aircraft that I have worked on wired up in this fashion.. Since most
Velocitys do not use post lights, but rather flood or ring type lighting,
there is no need for a 'ground' surface at all on the panel.

One other thing, if the aluminum panel edges starts to vibrate and rub
against the fiberglass, it could and probably would wear down the epoxy
and start to cut through the fiberglass. Unchecked, this could lead to a
long term disaster. Two like materials rubbing on each other greatly
reduces that potential problem.

The manual says it is not recommended. It is ultimately your choice.

One reason fiberglass hasn't been used for instrument panels in
production aircraft is because of the lack of quantitative analysis on
strength, quality assurance standards, etc. etc. for fiberglass by the
FAA. One of the reasons the Beech Starship became the pig it became was
because of the FAA's lack of understanding about the properties of
composite materials. I believe I read somewhere  that Rutan said that
plane could have been considerably lighter, and faster, if the Fed's
hadn't tried to apply archaic metal standards to composite material. And
the FAA is notorious for delaying or shooting down all together ideas
that are NIH (not invented here), meaning 'by the FAA'. 

Safe and Speedy Construction

Martin

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