THE YELLOW BIRD
Mapp Gas Cylinder Steam Rocket
YELLOW BIRD benefits from all the other steam rocket designs. Use only a
Bernzomatic brand tank. Start by burning out every bit of Mapp gas when a tank
is nearly empty by lighting the torch and letting it burn out.
Check that the torch fitting is square with the tank body. If it isn't,
tap the high side with a hammer lightly and keep checking it until it is.
Drill out the tank fitting to 1/2" in the drill press. Tighten a hose clamp
on it and hold it with oil filter pliers. Blow out the metal chips. Pull out
the outlet valve by getting hemostats on the pin.
Hold plate, aluminum fins and stainless exit cone.
The hold plate is 3/16" steel with 59/64" and 1/4" holes drilled into it.
You may need to use a round file or a Dremel tool sanding drum to get the hole
to fit over the torch fitting. The rest is cut with a jigsaw or band saw.
The steel in the slots where the hold fork goes is bent back and forth until
it breaks free using a Crescent wrench with the plate in the bench vise. Then
use a 4 & 1/2" grinder with a 3/16" grinding disk or use a file to get the
hold plate to its final shape.
The tank with hold plate and exit cone.
A brass piece was silver-brazed over the relief valve after sanding off the
paint and fluxing. The hold plate was welded onto the tank fitting and the
center was pipe-reamed to smooth it out. About 3/8" is left straight for the
nozzle plug O-ring seat in the nozzle throat.
The 3 & 1/4" long exit cone was formed into a cone so that the joint was
overlapped 1/8". It was tack-brazed at the wide end to hold it closed. Then
the cone was precisely aligned and silver-brazed to the hold plate. Two MAPP
gas torches will be required. (It is VERY important to get the nozzle throat
and exit cone precisely aligned with the tank axis.) Then the cone seam is
fully brazed. See the STEAM ROCKETS page for tips on silver-brazing.
How the cone was held precisely for brazing.
This is the exit cone held in precise alignment for brazing to the hold
plate of YELLOW JACKET.
The fin mounts.
The fin mounts are 1/8" x 1/2" x 1/2" by 4 & 1/2" steel. They were TIG-
welded to the hold plate. The 1/16" aluminum fins are pop-riveted to the fin
mounts. The fin mounts push against the hose clamp tighteners while thrusting.
The body can and nose cone.
The primary and secondary chute savers.
The primary chute saver is an aluminum muffin tin. The secondary is a
coffee bag cut to 8 & 1/2" by 12 & 1/2" and then formed over a bottle into a
cup 2 & 3/4" wide x 4" deep, then taped on the bottom. The two chute savers
are then taped bottom-to-bottom.
The YELLOW BIRD.
The black arrow points to where the fuse exits the body. Duct tape will be
put down on the body and hose clamp to insulate the Estes ignitor from the
metal. Finally fuse primer will be put over the fuse tip and ignitor head.
The weight is 2 lb, 10 oz. without the 2 pints of water. The 30 in. chute
is deployed by an eight second delay (3" of pyro fuse). The chute charge is a
rounded 1/8 tsp of FFFFg black powder. A smaller chute can be used on windy
days. The rocket lands on the body can which can easily be replaced if
The QUICKIE base was modified for YELLOW BIRD.
The guide rod was moved closer. There is now a spring-loaded switch with a
continuity tester (clear LED). The yellow cord lights the chute delay fuse
and primer smoke signal. A second cord launches the rocket. If a smoke puff
is NOT seen, a third cord swings the torch away from the tank. In the video
the smoke puff is seen first.
To the right of the guide rod are the ignitor wires. To the right of those
wires is the chute cable anchored down at the hold plate. The battery is
sealed into the jar. O-rings are silicone 1/16" x 1/2" O.D., Dash 012 from
MSC, stock no. #06840128.
The YELLOW BIRD out at the field.
The white board is 31" long and is a size reference for the video. The 31"
board is 3/8" on the frame when printed full-size. The cords from right to
left are fuse-and-smoke-puff ignition, release-rocket and finally one to pull
the torch away if no smoke puff is seen.
One frame of the video.
This shows perfect alignment of nozzle and fins.
The YELLOW BIRD launch.
Measurements from video frames show that the rocket was going 105 MPH, then
174 MPH then 246 MPH before going out of the frame.