Guy Norris/LOS ANGELES
TRW plans to make an aggressive bid for the future reusable launch vehicle market with a new, more powerful, version of the pintle rocket technology used in nearly all of its bipropellant liquid rocket engines, including the Lunar Module Descent Engine used in the Apollo programme.
The plan hinges on the success of final tests of TRW's Low Cost Pintle Engine (LCPE), and securing funding for more tests under NASA's second generation reusable launch vehicle risk reduction programme. The 650,000lb-thrust (2,900kN) engine, one of the largest liquid fuelled rocket engines built since the Apollo's Saturn F-1 engines, will be adapted to burn RP-1 kerosene in the next phase of the tests, "if we get the funding", says TRW.
Unlike conventional rockets in which propellants are introduced into the combustion chamber through thousands of machined holes, the TRW rocket feeds propellants through a large-diameter tube, or pintle. A plug in the base of the pintle forces the fuel to spray outwards in a thin, radial fan.
The propellant, in this case hydrogen, runs into the oxidiser at roughly a 90¹ angle, which is the optimum combustion angle, says TRW Propulsion Systems Center chief engineer Gordon Dressler, "This means we get a different geometry of forcing the two to mix and burn. So instead of producing a combustion zone, it forms a taurus cone which is much more efficient", he says.
The latest series of tests proved that an LCPE could handle varying propellant combinations and wide ranges of thrust levels and pintle configurations. TRW says the engine can be scaled to launch payloads ranging from 900kg to low Earth orbit, to heavyweight lifter class vehicles capable of carrying 90t to orbit.
Dressler adds that the concept has inherent combustion stability, and has proved this with more than 50 different pintle injector engine configurations, using more than 25 different propellant combinations. The LCPE "is a low tech route to low cost launchers", due to the use of off-the-shelf steel alloys, ablative cooling and the five-part pintle itself, allowing it to be offered at 10% to 20% of the cost of competing engines, says Dressler.
Source: Flight International
