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Manufacturer TRW and McDonnell Douglas
Country of origin  United States
Used on Delta 1000
Delta 2000
Delta 3000
General Characteristics
Height 5.9 metres (19 ft)[1]
Diameter 2.4 metres (7.9 ft)[1]
Mass 6,954 kilograms (15,331 lb)[1]
Engine details
Engines 1 TR-201
Thrust 43.63 kilonewtons (9,810 lbf)[1]
Specific impulse 319 sec[1]
Burn time 431 seconds[1]
Fuel Aerozine 50/N2O4

The Delta-P is an American rocket stage, developed by McDonnell Douglas and TRW, first used on November 10, 1972 as the second stage for the Delta 1000 series. It continued to serve as the second stage for subsequent Delta 2000 and Delta 3000 flights for 17 years, with its last usage on March 24, 1989. It is propelled by a single TRW TR-201 rocket engine, fueled by Aerozine 50 and dinitrogen tetroxide,[1] which are hypergolic.

The Delta-P has a noble heritage to the USA Moon program as the Apollo Lunar Module Descent Propulsion System. The TR-201 engine is the Descent Propulsion System modified to be a fixed thrust engine.[2] The Descent Propulsion System was first fired in flight during the Apollo 5 mission, in a low Earth orbit test on January 22, 1968.

As the supply of these surplus Apollo engines was depleted, the Douglas/Aerojet Delta-K upper stage was introduced in the Delta 3000 program. The Delta-K was then exclusively used on the second stage for the Delta 4000, Delta 5000, and subsequent Delta II.


  1. ^ a b c d e f g Wade, Mark (1997-01-30). "Delta P". Encyclopedia Astronautica. Retrieved 2008-06-22. 
  2. ^ Wade, Mark. "TR-201". Encyclopedia Astronautica. Archived from the original on 6 July 2008. Retrieved 2008-06-22.