L 400

The L400 is a liquid bipropellant rocket engine using isopropanol as a fuel and 50% hydrogen peroxide as an oxidiser. Potassium permangante is solved in the fuel and acts as a catalyst. The motor is ignited by a cartridge of potassium nitrate/sorbitol pellets.The motor is ablatively cooled by a fiberglassed phenolic liner. Its outer layer consists of two layer of Kynol felt. Kynol felt is used in fireproof suits, and is designed to withstand heats up to 700 C for up to two minutes (click here for a picture of the felt exposed to burning black powder). As the chamber temperature lies at 2052 C, there will be plenty time before the flame front burns through the felt and actually touches the chamber wall. For the regression rate, see the Static Test section. The liner will be thick enough to protect the chamber walls for a maximum burntime of approximately 20 sec.

Engine parameters:

Fuel: Isopropanol (95%) Oxidiser: Hydrogen Peroxide (50%)

O/F rate: 9:1

Isp: 221s (GDL GUIPEP data)

Thrust: 400 N

Burntime: 10 s

Impulse: 4000 Ns

Chamber pressure: 300 PSI

Chamber temperature: 2052 C

Fig. 1 Assembly without the ablative liner

Click here to see the injector and the injector cap.

Fig. 2 Nozzle

Click here to see the nozzle and o-rings

Fig. 3 Ablative liner

And finally, all parts together and the assembled engine.


I would like to thank Mr. Reinhold Wegener for his commitment, expertise and excellent machining skills during the construction of the engine as well as his patience and guidance throughout the design phase.

Excellent and prompt service was also given to me by Julia Willer and the staff at Kynol Europa, Hamburg in providing the necessary heat resistant materials at no charge. More info on that company can be found at their webpage (see Links section).

All metals were supplied by Schmitt Metalle.

Phenolic liner by Public Missiles.

Graphite by Aerocon Systems Co.

Solenoid valves by END Armaturen