THE BLUE BULLET
Water Bottle Steam Skyrocket
This skyrocket-type steam rocket was constructed after discovering that a
stainless steel water bottle could hold 600 PSI or more.
First stainless water bottle test.
The launch base is the same one used for the GREEN MONSTER and LEPRECHAUN.
To keep the weight and complexity to a minimum, a wooden guide stick was used
instead of fins. This required drilling a hole in the base for the stick plus
putting the launch base up on a stool.
The dry weight of the rocket is 11 oz. The smoke locator in the nose cone
was fused to ignite on the way down near the landing point or after landing.
BLUE BULLET stainless steel water bottle rocket.
The bottle closure is a brass disk silver-brazed onto the water bottle. The
nozzle throat is a brass fitting drilled 1/2" and silver-brazed to the disk.
The hold plate is 1/8" x 1" x 2" steel silver-brazed to the fitting. The exit
cone is 24 ga. stainless silver-brazed to the hold plate.
The guide stick is epoxied to the straight upper part of the bottle and
then wrapped with 24 ga. steel wire in case the heat softens the epoxy . A
coat hanger "fishook" on the hold plate aligns the guide stick at the bottom.
There is a tin flame guard between the rocket and the guide stick that is
pulled away right before launch.
BLUE BULLET on the base.
The hold-down force required at 600 PSI is 118 pounds. The launch base is
C-clamped to the stool and a 25-lb. hand weight anchors the stool. The battery
that burns the ignitor to light the smoke charge fuse is on the base and is
switched on by the pull cord after the flame guard tin is pulled out. Next the
hold fork support bolt is kicked out to launch the rocket.
NOTE: The smoke charge was 2/3 perc & 1/3 powdered sugar in a cardboard tube.
A smoke charge can also be made using the powder from a smoke cartridge.
The first video frame after release.
The next video frame.
The stool is 29 inches high. The rocket has gone 37" (3.08 ft.) in 1/30
second, the time between frames. That means it's going from zero to 93 ft/sec
(63 MPH) in 1/30 sec. which is 2784 ft/sec/sec or 87 g's.
We did not notice it at the time, but the high pressure caused the neck of
the water bottle to distort 7 degrees, plus the guide stick was broken early
on and so the flight path was a corkscrew.
The Blue Bullet II.
This new version has the nozzle assembly brazed directly onto the bottle
after the distorted part was cut off. A heavier guide stick (1/2") is hose-
clamped on. There is no nose cone. The smoke cartridge is duct-taped to the
guide stick above the bottle. The delay fuse goes through a hole in the side
of the smoke tube and is glued in. An Estes ignitor lights the fuse and a
black powder puff signal. (No puff, no launch). The weight of BBII is the
same, 11 oz. without water.
The first frame after launch.
The second frame after launch.
The third frame after launch.
The rocket has gone 6.2 feet from the first frame after launch to the next,
which is 186 feet/second or 127 MPH. From the second frame to the third frame
it has gone 9.31 feet, or 280 feet/second or 191 MPH. The acceleration between
the intervals is from 186 ft/sec to 280 ft/sec in 1/30 sec, or 2820 ft/sec/sec
which is 88 g's, even with the heavier stick.
BLUE BULLET II launch video.