Yeah, those bulkhead frames are a real pain to make and I'd like to find
a way to make them simpler. There are two concentric rings with a web in
between and the inner one has built up pads with dog point set screws.
Those mate up with small holes in the heel of the tanks to hold them in
place and for the design to work, the two rings have fairly stiff
relative to each other. I thought about having them 3D printed but the
design was flagged as "low chance of success" when I uploaded it. I
machined those by hand but I may have access to a CNC mill which would
make it much easier next time. The hardest part was machining the thin
sections. I used modeling clay as a backstop around the outer edge
while cutting out the inside.
-Bob
On 08/12/2018 10:25 PM, Ray Rocket (Redacted sender ar0cketman for
DMARC) wrote:
Really nice work, Robert. Have you considered building the ring from sheet
instead of carving it out of billet?
--------------------------------------------
On Sat, 8/11/18, Robert Watzlavick <rocket@xxxxxxxxxxxxxx> wrote:
Subject: [AR] Rolled aluminum fuselage
To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
Date: Saturday, August 11, 2018, 1:54 PM
To follow up on our discussion a few months
ago, I finished a test part
using 0.016 inch 2024-T4 sheet over
stringers for a 6 inch OD fuselage.
It turned out pretty nice and is plenty
stiff enough. The slip roll I
had access to at the Dallas Makerspace
had rollers too large so I ended
up rolling it by hand over a piece of
1.5 inch schedule 40 PVC pipe. It
wasn't completely round after rolling
but it was better than trying to
bend a flat sheet at assembly time. I
made some drill jigs for the skin
and stringers and used a single #30
slip fit bushing to drill the
holes. I probably don't need flush
fasteners for this rocket but I
wanted to try it anyway so I dimpled
the skin and then used a
countersink on the holes in the
stringer to accommodate the skin. The
fasteners were AACS-04-02 blind
rivets. I plan to use this arrangement
for the tank sections where I don't
need access and then use nutplates
for the other sections.
Photos:
http://www.watzlavick.com/robert/rocket/rocket1/photos/dsc_7257m.jpg
http://www.watzlavick.com/robert/rocket/rocket1/photos/dsc_7253m.jpg
http://www.watzlavick.com/robert/rocket/rocket1/photos/dsc_7251m.jpg
http://www.watzlavick.com/robert/rocket/rocket1/photos/dsc_7248m.jpg
There's some more detail on the main
page.
-Bob
