(Contributed - by Michael Wilkins - 09/27/04)
The EXB was my L3 project. Materials used to build this rocket were those in
the form of Carbon Fiber, S-Glass, Composite fin material and phenolic tubing.
The main technique in construction of the air frames was . Along
with the rocket I built a custom launch pad to make my L3 project complete. For
those that ask what is an EXB. The EXB is a 1/4 scale of the Nike Zeus
recognized by most as the Nike-X. It was built with several goals in mind.
First was to build it strong and durable so that it may last for a while and
get many flights. Second was to design it to handle the largest of 98mm motors
in commercial and experimental formulations. As for the name EXB, well you will
have to figure that one out on your own.
The parts list is pretty long but I will give you a list of the basics. The
tubing order consisted of three 48" long sections of 7.5" diameter
airframe, one 48" long section of 7.5" coupler tubing along with two
standard 12" couple tubes, one 48" long section of 3.9" motor
tubing. All tubing is phenolic. The fins are constructed from two materials.
The four lower fins are 3/8" thick Kevlar
composite material that were cut from two 12" x 36" sheets. The
remaining twelve fins are crafted from 3/8" thick birch plywood. There is
a total of 13 centering rings and bulk plates some of which are made of
composite material. The nose is fiberglass. Recovery is taken care of by an
RDAS, Altacc and two Skyangle Cert3 chutes attached by tubular Kevlar.
motor mount was first. All centering rings were trued and drilled for four
sections of all thread. A nut and washer is placed on both sides of each
centering ring and secured with Locktite.
The fins were measured and cut. The lower fins were trimmed with 3/8"
thick basswood. There is a total of 16 fins on this rocket. All fins are vacuum
bagged with one lay up of 5.7oz carbon fiber and one lay up of 4oz s-glass.
Once the fin can/motor mount was complete I started on the airframes. The
airframes were done in the same fashion as the fins. This time with a double
lay up of carbon and a double lay up of s-glass. After the air frames were in
their bags, they were placed into a curing oven. I would bag and cure one
section at a time. The airframe and nose cone were slotted with a router and
test fitted with the proper set of fins.
The avionics bay is a standard design. Flight computers are accessed via a
cover on the front of the rocket. The inside of the e-bay is bagged with a
triple lay up of carbon for extra protection.
After all subsections were assembled, any piece that had a fin joint got
filled. Fiberglass was then laid across the two lower fin groups. The
"make it look good" process was done in the automotive way. Filled
and blocked down with metal glaze, primed and sanded, base color sprayed, taped
off and the second color sprayed.
I now have a rocket with nothing to launch it off of. Remedy: build a
launch pad. My pad is built of steel square tubing. The base has a foot print
of fifteen feet and a deck height of three feet. The rail is two sections of
eight feet long 1515 T-slot. These are mounted to two sections of
1.5" square tubing. The tubing is then backed by twenty feet of antenna
lattice. The lattice rail assembly is attached to the base by four pillow
blocks with a one inch steel shaft. This enables the tower to be laid over for
the loading of rockets.
SUCCESSFUL LEVEL 3 FLIGHT!
June 20, 2004
Rocket - EXB
Weight - 100 lbs
Motor - Aerotech M2400
Altitude ~5,000 feet
Being a scratch design, the recommended motor for it was the bigger the
better. That holds true for this one.
First flight was at Wayside, Texas for my L3 cert flight. For my first M
flight, the Aerotech M2400T was chosen. The flight was a success and I made my
L3 cert. Altitude was measured as 4800' on the RDAS and 5200' on the Altacc.
Second flight was in Windom, Texas at the NTHP event. I decided I needed a
bigger motor this time around. An M1939W was called up for duty on this one.
Altitude for the bigger M was 6300'. There is an experimental N and possibly an
O in the near future for this rocket.