COBRA

COBRA is a liquid oxygen/hydrogen single-preburner, fuel-rich-staged-combustion engine scaleable from 200k-1000klbf.
Pratt & Whitney and Aerojet have teamed to provide the widest range of main propulsion options in support of second generation, reusable launch vehicles (2GRLV). Pratt & Whitney’s strengths in reusable rocket turbo-machinery and health and maintenance management systems used for jet engines complement Aerojet’s strengths in combustion devices and the integration and production of large propulsion systems such as those used for Titan.

Propulsion systems offered by Pratt & Whitney-Aerojet Propulsion Associates cover a wide range of thrust, for both hydrogen and hydrocarbon propellants, allowing the greatest flexibility for vehicle customers and NASA to select and execute optimum 2GRLV architecture.

One of these propulsion systems is the COBRA, a long-life, moderate-to high-thrust, reusable booster engine that incorporates a safe, low-cost, low-risk, LH2/LOX single burner, fuel-rich, staged combustion cycle. Mature, flight proven Space Shuttle Main Engine alternate turbopumps reduce technical, schedule, and programmatic risk while at the same time meet safety and reliability goals.

Description

Single pre-burner, fuel-rich staged combustion cycle
Double containment, failsafe powerhead, hot gas system
Incorporates flight-certified SSME Block II turbopumps
Long-life, robust, milled-channel nozzle construction eliminates hot side weld joints
Smooth start transients avoid life-limiting thermal stress
Blanch-shielded, formed-platelet liner technology reduces hotwall stress
Turbine inlet temperature reduced 500°F relative to the SSME, promotes longer life
Integrated engine controls and health management system enhance safety and maintainability
Low development cost/risk based on use of flight-qualified hardware and mature technologies

Characteristics

Thrust (vac): 200,000-1,000,000 lbf

Dry Weight (at 600k thrust): 8,000 lbm

Specific impulse (vac): 455 sec

Cycle: Staged combustion

Propellants: Liquid hydrogen / liquid oxygen

Mixture ratio: 5.5:1 to 6.5:1

Shutdown reliability: 0.9995

Catastrophic reliability: 0.999995

Mission life: > 100 missions

Time between overhauls: > 50 missions

Scheduled maintenance per flight: < 100 man-hours

Turnaround between flights: < 16 hours

Books:

- Modern Engineering for Design of Liquid-Propellant Rocket Engines (Progress in Astronautics and Aeronautics, Vol 147
from Amazon.com, Amazon.co.uk

- Rocket Propulsion Elements, 7th Edition by George P. Sutton (Author), Oscar Biblarz (Author)

- Rocket Exhaust Plume Phenomenology by Frederick S. Simmons
from Amazon.com, Amazon.co.uk

- Amateur Rocket Motor Construction: A Complete Guide To The Construction Of Homemade Solid Fuel Rocket Motors
from Amazon.com

COBRA Links

Cobra - Pratt and Whitney: Information and picture source (19 August 2007)

Goto Rocket Engines Guide

Goto Propulsion Guide Home Page

Goto Space Projects and Info Home Page