REFLECTOR: Door Trim Sealing

["Joe Stack" <joestack@technologist.com>]

I also had a few ill fitting spots on the door where there is almost a 1/2"
discrepancy between the door and the fuselage wall.  I worked for hours to
try to get a better fit between the molded doors and the fuselage and this
was as close as I could get.  These I dealt with by patiently filling with
Super Fill and sanding and shaping.  It looks like the results will be
satisfactory but I was annoyed that the parts didn't fit better.

I've been ruminating over the seal problem for a while, and I think I'm
gravitating toward a solution that is a combination of the larger bulb in
addition to the filler on the inside door flange.  The more I think about
it, the more convinced that the tiny 3/8" bulb is the wrong part for the
job.  I think that for the places where there is the nominal (1/2" fit) gap,
a trim selection with a larger bulb size is required.  I believe that I can
add to the door flange in those places that need it for a uniform seal
without adding noticeable weight to the door and without making the door
look it has "orthopedic shoes".  As Greg observed, the addition has to be to
the flat part of the flange (as opposed to in the corner) so that the bulb
compression comes with inward pressure on the door; otherwise you won't be
able to get the door to close properly.

While I don't have any "before" measurements on the noise level, I do intend
to make a series of measurements when I fly.  Several months back I visited
the ANR web site of Texas Instruments and I saw that they had free software
available for engineering spectral analysis (all you need is a decent
microphone and a laptop).  This is used for folks who buy their Digital
Signal Processors.  There is lots interesting information about passive and
active noise reduction available, but the first (and easiest) step is to
deal with the obvious.

Finally, regarding the cost of noise reduction.  Let's see...
* High end Bose ANR headsets go for about 1K each: $4000.
* The good David Clark passive headsets go for about $300 each: $1,2000
* Velocity sound proofing kit: (call for quote)
* Your nerves & hearing: PRICELESS ;-)

There's no question that the high noise level in GA airplanes contributes to
pilot fatigue.  I think that the aft engine configuration in this design
offers an excellent opportunity to reduce noise levels to levels that could
make headsets unnecessary.  How much aggravation needs to be expended for a
reasonable return?  I don't know.  We will probably never get it as quiet as
your car (without it weighing that much)... but it seems that to get even
close would make it well worth the effort.

Regards,


Joe Stack
N983SC - XL/RG