Encyclopedia Astronautica

Kayser N2O4/MMH rocket engine. 1 N. Satellite orientation. Isp=303s. Tangential Injection and Rotational Combustion, the world's smallest thruster burning monomethylhydrazine and nitrogen tetroxide.

Lutz Kayser invented, developed, and tested the TIROC rocket engine (Tangential Injection and Rotational Combustion). It was the world's smallest thruster burning Monomethylhydrazine and Nitrogen tetroxide. It delivered 1 newton thrust (0.2 lbf) with a minimum burning time of 1 milliseconds and a demonstrated maximum burning time of 1 million seconds (11 days). The valves had response times of under 1 millisecond and were capable of more than 1 million cycles at a 6 sigma confidence level. Kayser also developed one of the first capillary action gas-liquid separation systems. This guaranteed positive liquid flow from propellant tanks to the rocket engines in zero-gravity. Future applications were high performance satellite and space vehicle attitude control systems.

The TIROC was licensed by unknown US manufacturers and used in classified US DoD satellites. Characteristics were:

  • Propellants: N2O4/MMH
  • Thrust: 1 to 10 Newton
  • Tmin: 10^-3 Seconds
  • Tmax:>10^6 Seconds
  • ISP: 303 Seconds at 100 expansion ratio into vacuum
  • Valve response:10^-3 Seconds
  • Propellant inlet pressure: 40 bar to 10 bar range (600 psi)
  • Chamber material: Pt90-Rh10 or Be for the larger thrust
  • Dimensions incl. magnetic valves: 2x2x6 cm
  • Mass: 80 gram
  • Voltage: 24 VDC @ .5 A opening, .1 A holding current
  • Injector type: purely tangential leading to a rotating combustion with Bessel-function gas liquid separation.

This propulsion system was human-rated because the combustion chamber was unexplodable and could be fired handheld.

Because of the low thrust acceleration capillary action gas-liquid separation in the propellant was recommended

Bipropellant rocket engine (thruster) applications included: Satellite attitude and position control, re-entry systems, intra-orbit propulsion, docking, astronaut EVA, momentum gyro discharge.

Application: Satellite orientation..


Engine: 0.0800 kg (0.1760 lb). Area Ratio: 100. Restarts: 1000.

Unfuelled mass: 0.0800 kg (0.1760 lb).
Height: 0.0600 m (0.1960 ft).
Diameter: 0.0200 m (0.0650 ft).
Thrust: 1.00 N (0.20 lbf).
Specific impulse: 303 s.
Burn time: 1,000,000 s.
First Launch: Early 1960's.

More... - Chronology...

Associated Countries
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Associated Manufacturers and Agencies
Associated Propellants
  • N2O4/MMH Nitrogen tetroxide became the storable liquid propellant of choice from the late 1950's. Monomethylhydrazine (CH3NHNH2) is a storable liquid fuel that found favour in the United States for use in orbital spacecraft engines. Its advantages in comparison to UDMH are higher density and slightly higher performance. More...

  • Kayser, Lutz, Personal communication, 2005.,

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