Pegasus |
Orbital Sciences
Corporation * Alliant Techsystems
Pegasus
is a small commercial launch vehicle developed by Orbital Sciences Corporation.
Pegasus is an air-launched, solid-propellant booster with wings. It is launched
from B-52 (Pegasus) and than L-1011 aircraft (Pegasus H and XL). The current version
of Pegasus is the Pegasus XL,
which is longer than the original Pegasus (-H) configuration.
The first stage of Pegasus consists of an Orion 50S solid motor, a delta planform
composite wing, and an aft skirt assembly with three composite aerodynamic control
fins. The Orion family of motors was developed by Hercules (now part of Alliant
Techsystems). The Orion 50S-XL motor for Pegasus XL contains 24% more propellant
than the Orion 50S used on the original Pegasus.
The second-stage motor Orion 50 is very similar in design to the first-stage motor
and includes a similar core burning grain and forward dome igniter. The Orion 50-XL
motor for Pegasus XL contains 30% more propellant than the Orion 50 used on the
original Pegasus.
The third-stage motor incorporates a head-end grain design to maximize propellant
density. The third stage also uses a flexseal nozzle and electro-mechanical actuators
for TVC and employs a toroidal igniter. The third-stage Orion 38 motor has not been
stretched from the original Pegasus configuration.
There is an optional liquid fourth stage for the Pegasus and Pegasus XL, the HAPS.
The HAPS uses a hydrazine propulsion subsystem located inside the existing avionics
deck to increase launch vehicle accuracy above an altitude of 600 km. HAPS is restartable.
The payload fairing consists of a two-piece
carbon-composite shell structure, a nose cap integral to one of the shell halves,
and a separation system. The fairing maintains the 1.27 m outside diameter
of the second-stage motor and completely encloses the smaller diameter third-stage
motor, payload, and avionics subsystem.
Dimensions of Pegasus XL