The Ugly Bug
May 19, 2001
My first true 'scratch-built' model rocket was the Ugly Bug. It is based on the
Estes Mosquito, but built for an Estes 'D' (24mm) motor rather than the standard
mini-motor. This is actually not the first time I've built a scaled-up Mosquito, but I
don't really count the first time as a rocket. Back in grad school a fellow student
who had never seen a model rocket was curious about them. I didn't have any built
models, but did have a spare D booster motor sitting around and had an idea. We added
some balsa fins, a wooden nose cone, and a launch lug made from paper and glue formed
on a drill bit. This little assembly went like stink off the pad and we promptly lost
track of it. We found it sitting in the parking lot later, and the other grad student
repainted it, plugged the burned-out motor with glue, and hung it on the wall of his
office.
Years later, I was working on a true scaled-up Mosquito design about 14" in length with a
full parachute recovery system. However, I wasn't finished with it by the time a
NDRA launch came around. Not wanting to
bring only mundane models to the launch, I decided on a thursday night that I should build
another of the 'flying motor' D birds to get rid of some D12-3 motors I had. The delay
on these was too short for my only D rocket at the time, so they seemed good candidates
for glued-on fins. Part-way into building the first one, I thought, "Heck, why go to
all this trouble when I could add a body tube and have a real, reusable rocket?" Thus
the Ugly Bug project was born.
It was thursday night, and the launch was saturday morning. I had less than 48 hours to
actually build a rocket. "No problem," I figured, "I'll just use whatever I can find and
keep it super-simple." Since I had no actual kit parts, I'd have to scrounge and
scratch-build everything. I decided to keep to the original Mosquito recovery system, which
is 'featherweight'. This means the rocket ejects its spent motor and is so light it won't
be harmed by the fall. This works fine for a model barely bigger than a mini-motor, but
looking back on it was probably wishful thinking for a D bird. In any case, I started
scrounging around the garbage and my rocket shop and gathered the needed materials.
For the bigger scaled-up Mosquito, I had been toying with the idea of using corregated
cardboard wrapped in paper that had been soaked with wood glue (sort of like a composite
structure without using fiberglass and resin). I had gone as far a building a test
piece with this method, but had concluded it probably wasn't strong enough to build the
large fins of the 14" Mosquito. However, the test piece was the perfect size to cut
three fins out of for the Ugly Bug. I used the TLAR (That Looks About Right) engineering
method to determine fin size and shape, cut them out and sanded them to profile. Now
some form of body tube was needed. I located a hunk of dowel just slightly larger than
the 24mm D motor to use for the nose cone, and decided to use it as the form for building
a body tube. Back to the garbage for an old brown paper sack. I cut a strip of this,
rubbed it with yellow wood glue, and rolled it on to the dowel (which I had protected
with a wrap of plastic sheet to keep the glue from sticking). After the tube was formed
and rolled to remove excess glue, I slipped it off the form and set it aside to dry.
Next I sanded one end of the dowel to a nose-like shape using a belt sander. After a bit
of finishing hand-sanding, I used a bandsaw to cut the end off, leaving a 1/2" straight
section for gluing into the body tube. Finally, I formed a launch lug out of more
brown paper soaked with glue and wrapped around a drill bit. All these were set out to
dry overnight.
The next day, I used the bandsaw again to trim the ends of the tubes square and clean.
I used a D motor to measure how long the body needed to be, and trimmed it again. Then
all the parts were glued together and left to dry. Here is the result:
Now is when the name of the rocket suggested itself. Definately not my finest work, but
it would do for a 'throw away' rocket. When the glue had dried, I applied three coats of
blaze orange spraypaint. If you've ever flown a Mosquito, you know how easy it is to
lose them. I figured the paint was the only color that gave it a fighting chance of
being found. It took until 1:30 am that night, and the use of a hair dryer to speed
drying, but I finished the Ugly Bug and went to bed.
Here is the rocket (and its creator) at the third NDRA launch (May 13, 2001), about 30 miles north of
Michigan, North Dakota:
I had to build up some masking tape on the D motor to get it to fit inside the body
properly. Not having a recovery system or motor retention really simplified design
and building, but if I did it again I'd include a streamer for safety.
The first flight on a D12-3 went as I expected: the rocket shot off the pad to a very
impressive altitude, the ejection charged popped the motor out in a puff of smoke, and
the rocket vanished into the blue sky. The Range Safety Officer wasn't entirely
impressed with this, but knew the chances of it actually hitting someone and hurting
them was very low. We launched other rockets, then went looking for the UB.
Incredibly, it was found about 1/2 mile from the launch site. One fin had broken off
on landing, but was easily reattached with some quick-drying glue. Two fins had some
scorch marks on them where the exhaust gas had burned little holes in the paper
covering, but were still structurally strong. The UB was flightworthy again!
I debated if I should just count myself lucky and put the UB on my shelf, but then
rememberd I had expected to lose the little bugger and it was constructed more for
amusement of the spectators than anything else. I therefore decided to fly it again.
This time, I wanted to see just how high I could get it to fly. I had just flown
my Estes Snitch (plastic saucer) with a chad-staged D12-0, so I figured, "What the
heck?" I grabbed my last D12-3, taped it to fit the Ugly Bug, then taped a
D12-0 on the tail in the staged configuration:
The burned-out motor lying on its side on the blast plate is being used as a spacer to
keep the booster's ignitor from being shorted out. This is (surprise!) the last picture
ever taken of the Ugly Bug. Unfortunately, the center of gravity had been moved so far
back by the booster that the rocket was unstable during the first bit of its flight.
No loops or spins, but the rocket wandered around until most of the booster's propellent
had burned out. Just before staging, the CG had moved far enough forward to become
stable. At staging, the rocket was nearly horizontal and about 200' high. Staging
went fine, and the Ugly Bug shot off in an arc to the north west. At that altitude
and speed, the ejection charge puff wasn't visible, and we didn't even bother to go
look for the little rocket.
Thus was the end of my first scratch-built and aptly-named rocket. The 14" Mosquito
is nearly complete, and will be dubbed '
Big Ugly Bug', but will fly and return to the
ground in a much more sane manner (at least that was the plan. Select the Big Ugly
Bug link above to get the real story).