By Nick Esselman
Feeling a little bit like Rocky (you know, "I did it Adrian,
I did it!"), I completed my 29mm Mercury Transport. I originally planned
on building this rocket, but built an
version first just to test out the design. It worked and so did this 29mm
I actually built this almost two years ago, but there hasn't been an
appropriate Descon to enter it into, so ta-da....
The Mercury Transport's main purpose is to transport 4 passengers the 91.8
Million Kilometers to the planet Mercury for observation, study and
experimentation in a high temperature, zero gravity, high sun-radiation
environment. The Mercury Transport has fins that are suspended over the inner
Fusion Proton Rod Reactor Core. The fins are in a test configuration for future
interstellar travel and to assist in cooling the core as the ship passes close
to stars (such as our Sun). The ship is primarily designed for long distance
travel. In fact, 95% of the entire ship is a reactor to allow the ship to
travel the distance needed.
The 29mm (should be 38mm) Mercury Transport is made from components of the
Fat Cat Rockets'
rocket. I purchased the following from Fat Cat Rockets (now OOP):
- (2) Lower 4" Body Tubes (7.5" long)
- (2) Balsa Transitions
- (1) 2.6" Body Tube
The motor mount was a custom build with 4" centering rings for a
central 29mm and (3) 24mm motors. The 29mm motor tube was 12" long and
extended into the 2.6" tubing and had a 2.6" centering ring. This
effectively focused the 29mm ejection charge up the 2.6" tubing. (picture
is after last flight, even grass from the landing)
The recovery system consisted of an eye-bolt on the upper motor mount
(2.6") centering ring. Tied to that was 15 feet of 1/2" Kevlar.
The nose cone was one of
RGM's 4" Rounded Nose
I hand cut the fins from 3/8" Plywood. The long strakes are Walmart
Yard sticks with an angle cut from the corner to the 3" mark on each side.
Hey, these were a lot cheaper than buying wood and ripping it.
For recovery, I used a 50" rip-stop nylon parachute.
The build on this rocket is fairly straight forward. The transitions are
glued onto the 2.6" tubing until the tube is flush with the large end. I
used TiteBond Original Wood Glue for this. I then used the TiteBond glue and
spread it all over the outside of the balsa transitions to seal and strengthen
I then glued the two 4" tubes on each end using TiteBond. The shoulder
on the Fat Cat transitions is really short, but for both their Centaurus
and my Mercury Transport it is strengthened with external structures. In my
case, the 29mm motor tube extends into the 2.6" tube from the bottom and
the strakes attach to the outside of both sections of the 4" tubing.
Next, I built the motor mount and installed it using ProBond Polyurethane
comments about ProBond Polyurethane glue)
I marked the body tube using an old BSD guide that came with my
after extending the lines to convert from three fins to six. I marked the lines
on both 4" tube sections using a door jam.
At this point, I covered the 4" tubes and then used Plastic-Kote primer
to prepare the inner tube (2.6") for finishing. After the transitions and
inner tube were smooth, I painted them with Florescent Orange by Krylon. To my
disappointment, it did not come out as "bright" as my 18mm version.
The reason? I painted the 18mm right over the white body tube, whereas, on this
one it was over the gray primer. Lesson learned.
After a couple days for thorough drying, I taped and covered the inner tube
with paper to protect it.
Next was to prepare the strakes. After cutting the Walmart yardsticks from
the corner to the 3" mark on each end, I attached them to the body tubes.
I scuffed up the tube and then used TiteBond for this attachment.
I cut my six fins with through-the-wall tabs. Three had to be longer to
reach the 29mm motor tube, while three where shorter to attach to the 24mm
tube. I also had to ensure that the upper root section was cut at an angle to
match up with the yardsticks (strakes). After complete, I attached the fins to
with TiteBond and used a clamp on the fin to yardstick interface to keep them
I next used
Epoxy Putty sold by
Components for the fin fillets. All I can say is Wow! I like it! This stuff
was good to work with. I used water to dip my finger in for smoothing out the
epoxy fillets. I didn't think this would bond terribly well to the body tube or
wood as I didn't think it would penetrate, but after suffering flight damage on
the rocket, NONE of the breaks were on the epoxy bonds. Nice stuff.
After everything was dry, I used Plasti-Kote primer and Dark Navy Blue by
Krylon to finish it.
Lastly, I checked the center of gravity in proportion to my 18mm rocket and
determined that I needs some nose weight. I added nose weight based on my
RockSim file (which did not calculate the CP correctly as expected). I did this
by drilling two fill holes in the shoulder base and put in BB's. Then I poured
epoxy into the holes, shook it, and poured more, until I couldn't hear any BB
movement. I then capped it with another pouring of epoxy.
The final empty weight of my Mercury Transport was 70 ounces (4
lbs, 6 ounces)
For the first flight I decided to use an H165 plus three (3) F24's. I set it
up without any ejection charge in the F24's and was ready to go. A lot of nice
comments from others at the 2002 NYPower (see the picture someone took of me?)
so that was fun. I had trouble getting it onto the rail as I was the first one
to use this particular rail. I ran the rocket up and down multiple times, which
"cleaned" the rail. Then, I waited for the LCO to count down. And
waited, and waited. Finally it came time and the button was pushed and nothing
happened! I had to recycle it. There goes 1 hour. The next rocket on the same
pad (#30) failed to ignite too and therefore that pad was taken out of the
I went back the next day and tried again. This time something happened at
the "launch" command. The H165 lit and off she went. Ejection on the
"Short" delay was very early. The nose cone went a flying one way
while the rocket under 'chute descended nicely. The nose cone landed within 50
feet of the pad with no damage. The rocket landed a few hundred feet away with
That night I discovered that indeed (1) of the F24's lit too.
The next day, I loaded it up with an H238 plus the remaining two
(2) F24's and threw an E18 into the empty slot. After another hour and a failed
ignition. The Head Range Officer recognized that I needed a booster-battery to
light this combination, he "guaranteed" me an ignition and we
On the next cycle, I was loaded with a booster-battery and upon
"launch" my "guarantee" was satisfied. The rocket leapt off
the pad under the power of the H238 and at least one of the 24mm motors (as
seen in the picture) and at about 100 feet I heard/saw the remaining one or two
24mm motors ignite. I used
Burst Ignitors. I used a Fat Boy in the H238 and Twiggys in the 24mm
motors. The Twiggys had to be built into the motor as they did not fit through
the F24 or E18 nozzles. So, my guess, the H238 and E18 lit, while the two F24's
delayed a bit. The nice thing is that those ignitors stayed in the motors after
the H238 pushed the rocket off!
Well, again the ejection on the "Short" delay was very early. This
time the nose cone seems to explode. Several parts floated down. I never found
the nose weight. Don't really know what happen, but I have a guess. My guess is
that the BB-epoxy nose weight fell upon ignition and then upon ejection, at the
limit of the shock cord (non-elastic), slammed into the top the nose cone and
The rest of the rocket descended and hit hard, hard
ground. It broke one fin and strake off. But notice that it did not break the
epoxy, so again, I am very pleased with the
Epoxy Putty. I have decided to R.I.P. this rocket and move on to my next
project. This was fun!
In hindsight, I would recommend that this be built with a 38mm motor mount
and forget about the cluster. And that is it, really!