The ERPS has several engine projects in the works. These represent an evolving design philosophy that builds experience and expertise incrementally with lots of testing and tinkering along the way. The old "build a little, test a little" philosophy used so well by people like Kelly Johnson of the Lockheed Skunk Works is the foundation of the program.
These are the engines of the ERPS development test program:
The Bazooka is a monopropellant test engine that started life as the rocket motor for a
classic Bazooka Anti-tank weapon. It turned out that one we picked up at a surplus sale had almost
exactly the right throat diameter and could be cut down to give the proper expansion nozzle size.
This engine was used in the early "silver screen" tests of existing catalyst technology
but was replaced by newer engines custom built by ERPS as the test program proceeded.
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50 lb Monopropellant Engine
The M50 is a monopropellant test engine with supports for a load cell to permit measuring thrust.
Several of these engines were used in developing and testing performance of the catalyst and of peroxide
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M50-2 Instrumented Engine
The M50-2 is a sturdier variant of the M50 engine with multiple taps to provide ports for
thermal sensors as well as a support point for the load cell. This engine is also of ERPS design
The M250 is a stainless steel spun engine designed to provide 250 lbs thrust when configured
with a monopropellant feed head. This engine will be used in testing rapid cycling of the firing valves
and throtle-down capability and cycle rates for use in the Protina class vehicle as landing thrust.
The B500 is a stainless steel spun engine designed to provide 500 lbs thrust when configured
for bipropellant feed. It is the test engine for bipropellant operations and will likely power the
Protina class small, reusable test vehicle during ascent phases of flight.
The M750 is a stainless steel spun engine designed to test scalability of engine performance
and to be used in early flight test vehicles. A number of these were manufactured at the same time to
ERPS specifications and then modifications were made to test specific aspects of performance:
catalyst pack size, thermal and restart cycling, and burn duration.
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B1200 Bipropellant Engine
The B1200 is the first bipropellant design, made by modifying one of the M750 engines to use
a wrapped catalyst pack and a kerosene spray head for injection of the fuel. It is used to do initial
bipropellant testing and spray head optimization plus mix ratio tests, performance tests and throttling
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B5000 Bipropellant Engine
The B5000 is the main bipropellant design goal. By scaling up the B1200 design to
a full-sized, flight-weight engine, we plan to do extensive performance optimization testing before
licensing the engine for commercial production and sale.