Propane Tank Steam Rocket
This rocket is similar to the GREEN MONSTER, but made easier to set up and
launch. Any steam rocket with this fat type of propane cylinder and with a
1/2" nozzle throat has the highest acceleration of all these steam rockets.
The modified tank with exit cone and hold plate.
The 1/4" x 1/4" steel fin brace was welded to the hold plate. The hold
plate was welded onto the straight part of the propane tank fitting above the
threads. The exit cone is stainless, tapering from 1/2" to 1 & 5/8" diameter.
The seam was silver-soldered. The tank fitting was tapered inside with a pipe
reamer. The exit cone was then silver-soldered to the tank fitting and the
pipe reamer was used to smooth the steam flow. A brass disk was silver-
soldered over the relief valve fitting.
Everything is attached to the base, which is now smaller and lighter. It
is now easier to invert the base and to put the nozzle plug into the nozzle.
The rocket is 26 inches long. Weight without water is 2 & 1/4 lbs. Two pints
of rocket-fuel grade water adds two more pounds.
LEPRECHAUN on the base.
The hold-down force required at 600 PSI is 118 pounds. Chute choice is 30"
or 42", depending on wind. The chute is deployed after a 6 to 7 second delay
using 2 1/2" of fuse. The fuse exits the body tube and an ignitor is taped to
it. There is a bit of black powder to ensure that the ignitor lights the
fuse. The chute charge is a slightly rounded 1/4 tsp of Goex FFFFg.
The fuse-ignition switch.
The fine wire flips the switch to burn the fuse ignitor before the launch
lever knocks the hold fork support bolt away to release the rocket.
The primary and secondary chute savers.
The aluminum cup goes over the chute-eject charge upside down. The coffee
bag is taped to the aluminum cup. Together they form a chute-ejection piston.
The first frame after the launch of LEPRECHAUN.
The stool is a height reference in the video for speed measurements. The
umbrella is to block the wind.
The second frame.
The third frame.
The fourth frame.
LEPRECHAUN has gone 2.75 feet in 1/30 of a second, 82.5 feet/second, 56 MPH
in the first interval. It has gone 4 feet in 1/30 sec, 124 ft/sec, 85 MPH in
the second interval. Then 5.5 ft, 166 ft/sec, 113 MPH in the third
interval. The acceleration between frames 1 and 2 is 1254 ft/sec/sec, 42 g's
and 1242 ft/sec/sec or 39 g's in the second interval.
LEPRECHAUN launch video.
Under the chute.
This is a frame from a video of the launch shot by Jimmy Yawn which he very
graciously sent me. Jimmy is the sugar-rocket guru referred to on the
HOMEMADE FIREWORKS page.