- Soon after the "Verein Fur
Raumschiffahrt" (VFR: Society for Space travel) moved into the
Raketenflugplatz in September 1930, they decided to build what Rudolf Nebel
suggested be called a Minimum RAKete - MIRAK rocket series. Klaus Riedel
designed the rocket, bearing in mind the materials he had to hand.
- The copper engine, "a few inches
long", was based on Hermann Oberth's KEGELDUSE (Cone Engine), successfully
fired in July and August 1930. The engine was placed in the bottom of the
bullet-shaped Liquid Oxygen 5LOX) tank. A valve at the base of the LOX tank led
into the side of the engine. The gasoline tank was a slender Magnesium alloy
pipe fitted opposite the LOX valve. Somehow Nebel had managed to scrounge a
whole load of Magnesium piping, by persuading a stockiest of future large orders
when rocketry really took off.
- A Carbon Dioxide capsule was fitted to
the bottom of the gasoline tank. The gasoline supply pipe extended from the
bottom of the tank to the engine. The LOX tank was about 0,305 m long and 0,10 m
in diameter, while the "stick" was about 1,0 m long and 0,03 m in
- MIRAK-1 was set up on a stand at the
Raketenflugplatz for static test and fired late September 1930. Loading the
gasoline was straight forward enough. After the LOX tank was charged, its
pressure built up by its own expansion. At the appropriate moment, the gasoline
was pressurized and started flowing into the engine, after which the LOX valve
was opened and the little engine would have sprung into life. however at some
point in the proceedings, the LOX pressure rose too high, bursting its tank and
wrecking the rocket. Obviously the LOX tank was left pressurized too long.
- MIRAK-2 embodied considerable
improvements over MIRK-1, most notably a LOX pressure release valve on the head,
and also a larger capacity gasoline tank. The rocket was about 2,75 m long. Also
the engine was cooled more efficiently by having larger area in contact with the
LOX. A special static launching frame was built. In the spring of 1931, during a
number of static tests, thrust of about 32 kg were developed during the 10
second burn time. Later the engine burned through, and the rocket exploded
during a static test.
- MIRAK-3 was built while MIRAK-2 was
still under test in the spring of 1931. It had the same size 0,1 m LOX tank
head, but had four 0,03 m "sticks"; two for gasoline and two for
compressed Nitrogen. The engine was in the base of the LOX tank now. It was
between the "sticks" surrounded by a water jacket. Although this
quickly boiled, it kept the engine around 100 degrees centigrade on the water
side. Launch weight was 4,1 kg, and the engine had a thrust of between 9,1 and
8,2 kg, and could burn for 32 seconds. It made the VFRs first liquid propellant
flight on May 10, 1931 and rose to 18,3 m altitude. It was subsequently repaired
and launched as REPULSOR-1 on May 14, 1931.
Nr Vehicle Date Notes
1 MIRAK-1 Sept. 1930 Oxygen tank burst after loading, during static test
2 MIRAK-2 spring 1931 Exploded during a static test
3 MIRAK-3 10.05.1931 Success launch, rose to 18,3 m altitude
Note: all flights from the "Raketenflugplatz"