Spaceflight Now: Atlas Launch Report

The RD-180 engine
Posted: May 14, 2000

A two-nozzle RD-180 engine sits on display. Photo: Pratt & Whitney
The RD-180 is a two thrust chamber derivative of the RD-170. It packages the high performance, operability, and reusability features of the RD-170 in a size (933,400 lb thrust) to meet U.S. booster propulsion needs.

The RD-180 is a total propulsion unit with hydraulics for control valve actuation and thrust vector gimbaling, pneumatics for valve actuation and system purging, and a thrust frame to distribute loads, all self contained as part of the engine. The engine, employing a LOX lead start, staged combustion cycle and LOX rich turbine drive, delivers a 10 percent performance increase over current operational U.S. booster engines and provide clean reusable operation.

Lockheed Martin has selected the RD-180 engine to provide the booster propulsion for its Atlas 3 launch vehicle and its candidate for the U.S. Air Force's Evolved Expendable Launch Vehicle (EELV).

The RD-180 is a staged combustion cycle engine that burns liquid oxygen and kerosene propellants. The two thrust chambers can gimbal +-8 degrees. The engine has a health monitoring and life prediction system. Minimized interfaces are needed with launch pad and vehicle (pneumatic and hydraulic systems self contained, electrical panels consolidated, thrust frame to simplify mechanical interface).

The engine offers environmentally clean operations with staged combustion oxidizer rich preburner, and oxidizer start and shutdown modes that eliminate coking and unburned kerosene pollution potential.

Forty to 100 percent continuous throttling provides potential for real time trajectory matching and engine checkout on the pad before launch commit.

RD-180 facts  
Nominal thrust (sea level) 860,200 lb
(vacuum) 933,400 lb
Specific impulse (sea level) 311.3 sec
Vacuum specific impulse 337.8 sec
Chamber pressure 3,722 psia
Nozzle area ratio 36.87:1
Mixture ratio 2.72
Length 140 in.
Diameter 118 in.
Throttle range 40-100%
Total system dry weight 11,889 lb
Source: Pratt & Whitney/NPO Energomash

Flight data file
Vehicle: Atlas 3A (AC-201)
Payload: Eutelsat's W4
Launch date: May 24, 2000
Launch window: 2139-2358 GMT (5:39-7:58 p.m. EDT)
Launch site: SLC-36B, Cape Canaveral, Fla.

Pre-launch briefing
Launch preview - Read our story for a complete preview of the first Atlas 3A launch.

Launch timeline - Chart with times and descriptions of events to occur during the launch.

Atlas 3A vehicle data - Overview of the rocket that will launch W4 into space.

Eutelsat W4 - Description of the satellite to be launched on AC-201.

Launch windows - Available windows for future launch dates of AC-201.