>>E builders and riders:<<
I am muddling through chapter 23 right now. Busy cutting out the access
hatches and the "viewing hole" in the rear of the fuselage.
The forward hatch is too far away. At this time, I have no idea why the lower
hatch is even necessary.
Am I missing something here? Have any of you considered enlarging the
viewing hole for easier access to the things that will need future attention?
Perhaps I am missing some revelation a few chapters away?
You comments and wisdom please!
>>Brian Skelly<<
Brian
you aren't wrong. IMHO the view hole needs to be much bigger. If you do this,
make
sure all inspection holes are structural, ie capable of taking all the loads
in the skin across the hole. That means 6 screws in the larger holes.
A structural rule of thumb is " calculate the amount of glass cloth removed when
cutting out the hole, then add four times that area to make the flange around
the hole. Then the hole should be almost as strong without its cover as it was
before you cut it out." (I'm quoting the late much respected Barry Mellars
here, he did the original stress calcs for Ivan.)
Use the piece you cut out to make the cover, at least it will be the right
shape!
It pays to make the flanges before cutting the holes;
Release wax inside over the place for the hole,
Layup the flange, 4 ply BID
Drill 2 or 3 Cleco holes outside the hole position for location, also the screw
holes in the still imaginary cover
Crack the flange off then cut out the hole, I use a Stanley knife and a small
toffee
hammer. A fretsaw blade might do it even more nicely
Now the flange can be floxed back in place, the edges of the cover filled with
flox to a depth of maybe 4 mm.
Finally the fixing holes coutersunk and floxed in the same way, then screwed in
place with Tinnermen and allowed to cure.
Graham
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