J-3 New Cross
Members
----- Original Message -----
From:
Mike Midkiff
To:
Tandy C. Walker
Sent: Thursday, September 20, 2007 4:22 PM
Subject: Re: 4 J-3 Provisions for Burst Tube
Tandy
I would take out the arches and instead install horizontal 1/16 x 1/4 balsa
strips
against all top formers aft of the cabin. Install approx 1/2 way up on ea
one ahead of the
rear tube. Overlap these so that they are o/side to o/side. These will add a
lot
to the compression strength of the rear fuse and give plenty of motor
clearance( tube )
Mike
In the message above, Mike Midkiff provided me
with an excellent recommendation on a sudo cross member structure for the
top longerons in the aft part of the fuselage. The picture below shows the 4
added cross members as per Mike's suggestion. Thanks Mike!
As the picture below shows, the cross members
were kept as low as possible on the bulkhead legs, but still provided upper
clearance for the blast tube. Notice the thin section of fuel tubing keeping
the 3/16" aluminum motor peg in place
(an input from Gene Wallock).
For additional support, I added the 4 small
gussets to tie in the bottom of the two bulkheads on either side of the
fuselage side's vertical truss member to the top longeron. This adds very
little weight, but a lot of support.
Finally, I think I can move on with construction
now, but let me take this opportunity to thank all of you that have provided
me with valuable input. Especially Ed DeLoach who recommended the blast tube
in the first place. I hope you guys are enjoying my reports. Any time you do
not want the reports anymore, just let me know and I will remove your name
from the distribution list........Tandy