Fred,
Watch out for the effects of the speaker's magnet on the compass.
Dave Simpson
-----Original Message-----
From: Fillinger@aol.com <Fillinger@aol.com>
Date: 18 May 1999 01:41
Subject: Re: Ceiling panel
>Lloyd owns asked --
>> ...Coming up to bonding on the fuselage top moulding, so does anyone have
>any hints/tips regarding ceiling panels?
>
>Lloyd --
>
>Just completed that task today. I fashioned a piece of scrap foam to fit
>into the recess. To lighten it up, I routed a series dados in the foam (a
la
>lightening holes), micro'd it in place, and sanded it flush with the door
>seal flanges after cure. Mine fills only the forward 2/3 of the recess.
The
>last 1/3 is a .012" aluminum sheet, epoxy-tacked into place prior to laying
>up 2 layers of uni cloth with peel ply. The reason for the aluminum is to
>stiffen the glass and create a hollow space to mount a $4.00, 4-inch, 4-ohm
>speaker, pilot/copilot headphone jacks, plus an intercom. Yes, I know
I'll
>have to drill thru the foam and glass to affix door hinge attachment nuts,
>but some little nylon "idiot plugs" will fill the holes. With the rear 1/3
>hollow, I'll get at the nuts thru the speaker mounting hole. The 4-inch
>speaker with small resonance box behind won't do much for Vivaldi, but it's
>near the ears and is a headphone backup only.
>
>I know of no commercial intercom that will fit the recess, but I will be
>designing my own. Especially after paying for the 914, I'm not inclined to
>pay $300 for a couple of 25-cent op amps, a $1 audio IC, and handful of
>garden-variety passive components. Will save weight too, wiring the jacks,
>which otherwise would be long runs of shielded stuff. RST Engineering
>(www.rst-engr.com) has several circuit suggestions for intercoms published
on
>their site, for those so inclined.
>
>The foam/glass/ali weighs in at about 10 ounces. I even tinted the resin
>gray (using white and black epoxy pigments sold by System III Resins, et.
>al.), so minimum gray finish paint will be required (trying to save weight
>everywhere!). I couldn't think of an alternative arrangement that would be
>much lighter and easier to do. Looks professional even.
>
>Regards,
>Fred Fillinger, A063
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