HYBRID ROCKET MOTORS
R.A.T.T.Works Hybrid Rocket Motors
- Motor Casing
- Nozzle and Nozzle O-rings
- Tank Bulkhead, vent line and O-ring
- Floating Injector head, Injector and O-ring
- Threaded closures
- Fuel Grain
- Fill tubes
Introduction to R.A.T.T.Works Hybrid Rocket Motors
The R.A.T.T.Works hybrid rocket motors were the first hybrid motors to become commercially available in the U.K. They use a through-the-injector fill method, where the igniter burns through the fill tube to release the oxidiser into the combustion chamber. The R.A.T.T.Works hybrid rocket motors range from H-class to M-class performance, and are available in 29mm, 38mm and 64mm diameter.
The R.A.T.T.Works hybrid rocket motors are monotube hybrids, with both the combustion chamber, oxidiser tank, injector and nozzle contained within a single tube. The tubes are constructed from anodised aluminium. Generally, the R.A.T.T.Works hybrid rocket motors are anodised a deep purple colour.
Nozzle and Nozzle O-rings
The nozzles on the R.A.T.T.Works hybrids are designed to be used once only, and are fitted during the fuel grain / ignition assembly. The assembly is retained by an external knurled thrust ring which has a machined thread which after light greasing with Krytox Nitrous safe grease, enables it to be screwed onto the external screw thread on the monotube hybrid motor casing.
Tank Bulkhead, vent line and O-ring
The Tank bulkhead and integral vent line assembly has a screw thread machined into it, enabling it to be simply screwed into the top of the monotube casing. A groove below the screw thread allows the O-ring to be fitted. Before screwing into the monotube casing, the tank bulkhead and vent line assembly is lightly greased with Krytox Nitrous safe grease.
Floating Injector head, Injector and O-ring
The floating injector head is an anodised aluminium assembly containing 2 O-ring grooves and a brass screw thread to attach the compression gland and olive to retain the plastic fill line.
The injector doubles up as the flow valve - this system being known as the Urbanski-Colburn valve, after its inventors. The R.A.T.T.Works use of this system when introduced, represented the first commercial use of the Urbanski-Colburn valve in a hybrid rocket motor.
Each end of the monotube casing of a R.A.T.T.Works hybrid rocket motor is fitted with a screw thread. The tank bulkhead end has an internal screw thread, and the nozzle end has an external screw thread.
A polyethylene fuel grain is lightly greased with Krytox Nitrous safe grease,and slid into the combustion chamber.
A plastic fill tube is used to fill the oxidiser tank, with the plastic fill line passing through the combustion chamber and screwed into a brass compression gland and olive. In the R.A.T.T.Works hybrid rocket motors, the brass compression glands are fitted on the combustion chamber face of the hybrid rocket motor, facing into the combustion chamber.
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