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So I wanted a BIG rocket, cheap. I'd
seen Dave Flynn's Quik Rush and decided that Quik Tube was the perfect
material to build out of. It was cheap ($5 / 4 feet), light, and
relatively strong. I, of course, decided not to glass it in the
interest of time and money. The next best thing to do was to
cover the tubes in Polyester resin. I got some polyester resin from
the local marine supply, and proceeded to peel the tubes and coat them
with the stuff. First problem: POLYESTER STINKS! Think plastic
cement about 100x. It was so bad that I had to wrap the tubes in a
tarp and stick them outside, because the smell permeated into the house if
stored in the garage. Thankfully, the stink went away after the
tubes cured.
I sanded the outer surface briefly with a
power sander to smooth out some of the lumps. That was the basic
tube. The next question was where to get a cheap motor mount
material. I went down to the local Staples and bought a 3"
mailing tube for about $1.50. I checked it with a 3" to 54mm
adapter, and it fit. Presto, a 3" motor mount. I cut
centering rings with a RotoZip and a hole saw. After a day of
practice, I had the rings cut. The last step was to cut the
fins. I printed out a VCP template and sawed the four fins from
1/2" plywood left over from a cabinet project.
What to do about beveling these fins?
There was no way that I would bevel them by hand (it would take forever)
and my fin beveling jig wasn't up to the task of 1/2" fins. So
I went down to the hardware store and bought a 1/2" dowel in a flash
of inspiration. I then took a Dremel and a fiberglass cutoff wheel,
and after a couple of painful hours (can you say "flaming wood
chips"?), I had two halves of a dowel. Then I cut these to
length and attached them to the leading edge of the fins using #6
screws. A little wood filler and sanding later and I had my fins.
The motor mount was assembled with the
tube, rings, and four pieces of 1/4" all-thread, washered and nutted
at each ring. This was done so that the recovery forces would be
transferred directly to the aft ring of the rocket, and thus made the
outer tube only serve as a skin. I attached the rings with West
105/205 and Colloidal Silica. I then cleaned up the fillets and
attached the fins. They were tacked in place with 5-minute epoxy,
then filleted with West 105/205 and some milled glass fiber. To make
sure they didn't go anywhere, I also laid a strip of 9 oz. glass over the
fin fillet and onto the fin and tube.
I slotted the booster tube using a jigsaw,
and slid the fin can in. This got a cup of West 105/205 on the front
and rear centering rings, as well as a treatment on the two interior
rings. Couplers were created from another section of tubing, sliced
down the side and fitted to the tube. This would become the
anti-zipper coupler. In case of odd torquing forces on the coupler
at apogee, I attached it with (5) 6-32 tee nuts and screws. That
way, I can replace the coupler if need be. There is no bulkplate in
the bottom of the booster, to allow room for the HyperTek Hammerhead L
tank/M grain combo.
The coupler is also the location of the
electronics bay. I am flying this sucker with a MissileWorks RRC2
and an old Adept ALTS2 for backup. A single Rocketman R14C
Pro-Experimental is serving recovery duties. Since this rocket is so
simple, I just decided upon apogee deployment. Maybe I'll convert it
to same-end dual deployment later. The recovery tube is a single-walled piece of Quik
Tube reinforced with more polyester resin. And the nose cone is borrowed from
my Bruiser.
That's how to build a BIG rocket for $50
bucks.
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You start with this...
...and end up with this. |
