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The Centaur upper stage, fuelled by
liquid oxygen and liquid hydrogen, was initially developed by General Dynamics
to place military communications satellites into orbit. When the programme was
cancelled, the launcher was handed over for civilian use by NASA. In 1994 the
rights to the Centaur upper stage were sold to Martin Marietta, which in 1995
merged with Lockheed to become Lockheed Martin. The Centaur upper stage was first
used on 27 November 1963 after a failure on 8 May 1962.
The Centaur upper stage was extensively used for the Atlas launch vehicle in
a range of versions. The Centaur was also used for the Titan-3E and Titan-IV
launch vehicles, in two versions.
The Centaur T of the Titan-IV based on the Centaur G and Centaur G-Prime, with
diameter of 4.32 m. The Centaur G / G-Prime were planned as future kick-stages
for payloads on the Space Shuttle.
|
Type
|
Length
|
Fuel (t)
|
Engine P&W
|
Thrust (kN)
|
Isp (sec)
|
Used
for
|
Launches
|
| Centaur A |
|
9.14 |
13.79 |
2x RL-10A-3-1 |
133.45 |
? |
SLV-3C |
1 |
| Centaur B, C |
13.79 |
2x RL-10A-3-2 |
133.45 |
? |
SLV-3C |
4 |
| Centaur D |
13.79 |
2x RL-10A-3-3 |
131.23 |
442.2 |
SLV-3C |
24 |
| Centaur D-1A |
13.79 |
2x RL-10A-3-3 |
131.23 |
444.4 |
SLV-3D |
6 |
| Centaur D-1T |
13.79 |
2x RL-10A-3-3 |
131.23 |
444.4 |
Titan-3E |
7 |
| Centaur D-1AR |
13.79 |
2x RL-10A-3-3A |
131.23 |
446.4 |
SLV-3D, Atlas-G |
33 |
| Centaur D-1B |
I |
13.79 |
2x RL-10A-3-3A |
131.23 |
446.4 |
Atlas I |
11 |
| Centaur T |
|
11.73 |
20.86 |
2x RL-10A-3-3A |
146.81 |
446.4 |
Titan-IVA, Titan-IVB |
16 |
| Centaur G |
7.10 |
? |
2x RL-10A-3-3A |
146.81 |
446.4 |
Space Shuttle |
0 |
| Centaur G-Prime |
11.73 |
20.86 |
2x RL-10A-3-3A |
146.81 |
446.4 |
Space Shuttle |
0 |
| Centaur D-2 |
II |
10.06 |
16.93 |
2x RL-10A-3-3A |
146.81 |
446.4 |
Atlas-II |
10 |
| Centaur D-2A |
IIA |
16.93 |
2x RL-10A-4 |
182.38 |
442.5 |
Atlas-IIA |
8 |
| Centaur D-2AN |
IIA |
10.52 |
16.93 |
2x RL-10A-4N |
182.38 |
446.4 |
Atlas-IIA, Atlas-IIAS |
10 |
| Centaur D-2A1 |
IIA1 |
10.06 |
16.93 |
2x RL-10A-4-1 |
185.18 |
446.4 |
Atlas-IIA, Atlas-IIAS |
5 |
| Centaur D-2A1N |
IIA1 |
10.52 |
16.93 |
2x RL-10A-4-1N |
185.18 |
449.0 |
Atlas-IIA, Atlas-IIAS |
30 |
| Centaur D-3A SEC |
IIIA |
16.93 |
1x RL-10A-4-2 |
99.16 |
450.5 |
Atlas-IIIA |
2 |
| Centaur D-3B SEC |
IIIB |
11.73 |
20.67 |
1x RL-10A-4-2 |
99.16 |
450.5 |
Atlas-IIIB |
3 |
| Centaur D-3B DEC |
IIIB |
20.67 |
2x RL-10A-4-2 |
198.32 |
450.5 |
Atlas-IIIB |
1 |
| Centaur D-3B SEC |
V |
20.83 |
1x RL-10A-4-2 |
99.16 |
450.5 |
Atlas-V400, AtlasV500 |
26 (>) |
Atlas Centaur
The Atlas IIIA and IIIB vehicles
use the RL-10A-4-1 engine version. This engine incorporates Direct Spark Ignition
(DSI) and helium ground chilldown features, providing improved reliability
and increased performance.
The Atlas V vehicles use the RL-10A-4-2 engine. The RL-10A-4-2
engine has the benefits of the RL-10A-4-1 engine, and also incorporates several
new features that improve engine reliability and performance. Several significant
operational features are incorporated into the RL-10A-4-1 and RL-10A-4-2 engines.
Before launch, a gaseous helium chilldown of the LH2 and LO2 turbopumps is
performed. During the boost phase, a pre-chill of the LH2 turbopump is accomplished
by flushing LH2 through the engine and overboard. Both of these operations
reduce the amount of propellants that are used immediately before main engine
start and the associated wait time after separation, and consequently increase
performance. These features were proven out on the first Atlas IIIA, IIIB,
and V launches. Another improvement for the RL-10A-4-2 engine was the addition
of a fourth solenoid valve with plumbing that allowed for independent control
of the OFCV bypass. This enables trickle cooldown of the engine before second
or third engine starts for increased vehicle performance.
The most significant change that is part of the RL-10A-4-2 engine is the incorporation
of Dual Direct Spark Ignition (DDSI) system. The DDSI is a fully redundant
electronic ignition system that has been fully qualified at the component and
system level to the more severe Atlas V environments.
The change to a new booster for the Atlas V program provided an opportunity
to pre-deploy or fix the Centaur engine nozzle extension before launch. The
Atlas II and III families use a deployable nozzle extension that must be actuated
just before main engine start. The Atlas V vehicles, all using the RL-10A-4-2
engine, have sufficient space in the interstage area to allow the nozzle to
be fixed, consequently removing a critical event from the flight sequence,
improving reliability and performance. The RL-10A-4-2 engine can accommodate
either the existing extendible nozzle extension or a fixed nozzle extension.
The engine is gimbaled during flight by using two different flight-proven systems.
EMAs for thrust vector control were developed for the SEC program and are used
on all single-engine Common Centaurs.
Dual-engine Common Centaurs use the hydraulic thrust vector control system
that has been used on all previous Centaurs.
Source: Thomas J. Rudman & Kurt L. Austad; Lockheed
Martin, Space Systems Company, Denver, Colorado USA
4th International Conference on Launcher Technology; December 2002 – Liege
(Belgium) |
|
|
no image
|
|
|
|
|
|
|
RL-10A-3-1
|
RL-10A-3-2
|
RL-10A-3-3
|
RL-10A-3-3A
|
RL-10A-3-3A
|
RL-10A-4
|
RL-10A-4N
|
|
no image
|
no image
|
 |
 |
 |
no image |
 |
| Centaur A |
Centaur B,C |
Centaur D,
D-1A |
Centaur D-1AR |
Centaur D-2 |
Centaur D-2A |
Centaur D-2AN |
| SLV-3C Centaur |
SLV-3C Centaur |
SLV-3C Centaur |
SLV-3D, Atlas-G,
Atlas-I |
Atlas-II |
Atlas-IIA |
Atlas-IIA,
Atlas-IIAS |
|
|
no image
|
no image
|
|
|
|
|
RL-10A-4-1
|
RL-10A-4-1N
|
RL-10A-4-2
|
RL-10A-4-2
|
RL-10A-4-2
|
RL-10A-4-2
|
 |
 |
 |
 |
 |
 |
| Centaur D-2A1 |
Centaur D-2A1N |
Centaur D-3A
SEC |
Centaur D-3B
SEC |
Centaur D-3B
SEC |
Centaur D-3B
SEC |
| Atlas-IIA,
Atlas-IIAS |
Atlas-IIA,
Atlas-IIAS |
Atlas-IIIA |
Atlas-IIIB |
Atlas-V (2002) |
Atlas-V (2009) |
Titan Centaur
|
|
|
-
|
|
|
RL-10A-3-3
|
RL-10A-3-3A
|
RL-10A-3-3A
|
RL-10A-3-3A
|
 |
 |
 |
 |
| Centaur D-1T |
Centaur T |
Centaur G |
Centaur G-Prime |
| Titan-3E |
Titan-IVA,Titan-IVB |
Space Shuttle |
Space Shuttle |
|
