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Pegasus: (1990) Privately-funded, air-launched winged light satellite launcher.
Pegasus HAPS: (1991) Pegasus launcher with optional HAPS stage 4.
Pegasus XL: (1994) Uprated version of Pegasus air-launched winged light satellite launcher.
Taurus: (1994) Pad-launched launch vehicle using Pegasus upper stages and Castor-120 first stage. First launch used slightly larger Peacekeeper ICBM first stage instead of Castor-120.


First launch: 5-Apr-1990
Number launched: 10 through Mar-1996
Launch sites: now hosted by L-1011 operating out of Vandeberg AFB, NASA Wallops and Cape Canaveral (Spain's Minisat will be from Torrejon AB near Madrid)
Principal uses: small payload to LEO
Vehicle success rate: 80.0%
LEO (463 km equatorial): 3-stage typically 288 kg (XL: 382 kg); payload fraction 2.2%
Polar (463 km): 200 kg (XL: 279 kg)
GTO: 165 kg capacity projected with XL + stage 4
Availability: 1 flight/45 days projected
Cost: $53,000/kg or $12 million for 227 kg payload
Number of stages: 3
Overall length: 15.51 m; XL: 16.8 m
Principal diameter: 1.27 m (wingspan 6.71 m)
Launch mass: 18,518 kg; XL: 22,583 kg
Guidance: autonomous autopilot forward of stage 3, with Oettle & Reicher's 68430-based flight computer containing mission-specific mission data load (MDL). Inertial/attitude data are provided from Litton LR-81 Inertial Measurement Unit (IMU). Flight #2 demonstrated a Trimble GPS receiver for navigation. It is now standard; IMU is retained for attitude data. XL carries upgraded avionics for increased payload mass/dynamic volume

Stage 1 incorporates a Scaled Composites Inc graphite composite wing with 45o sweptback leading edge and 6.71 m span. Subsonic L/D is 4.0. The airfoil is a double wedge with 2.5 cm radius leading edge. The wing thickness is truncated to 20.3 cm, with upper/lower parallel surfaces facilitating attachment to the motor case wing saddle.
Motor: Alliant Techsystems Orion 50S (stretched 137 cm for XL); fixed nozzle
Length: 9.39 m; XL: 10.76 m
Diameter: 1.27 m
Mass at ignition: 14,020 kg; XL: 17,157 kg
Propellant: HTPB solid
Propellant mass: 12,152 kg; XL: 15,051 kg
Thrust: 486.7 kN vac average, 583.7 kN vac max; XL: 619.9 kN vac average
Total impulse: 35.05 MNs; XL: 39.9 MNs
Burn time: 72.3 s; XL: 64.3 s
Attitude control: control during stage 1 burn is provided by three active aft fins as part of an aluminum assembly attached to the motor's skirt extension. Control is augmented at end of stage 1 burn by firing small fin-mounted motors
Separation: the forward skirt, which also serves as interstage adapter, incorporates two linear-shaped charges
Burn sequence: vehicle is released from L-1011, activating sequencer and autopilot. At 2 s, the arming sequence begins for stage 1 arming/ignition at 3/5 s, respectively. Burnout occurs at 76-84 s

Motor: Alliant Techsystems Orion 50 (stretched 45 cm for XL)
Length: 3.84 m; XL: 4.29 m
Diameter: 1.27 m
Mass at ignition: 3,370 kg; XL: 4,314 kg
Propellant: solid
Propellant mass: 3,024 kg; XL: 3,919 kg
Thrust: 113.9 kN vac avg, 131.7 kN vac max; XL: 160.1 kN vac avg, 195.3 kN vac max
Total impulse: 8.67 MNs; XL: 11.22 MNs
Burn time: 75.9 s; XL: 70.1 s
Attitude control: motor nozzle flexing provides pitch/yaw control during powered flight; roll control and 3-axis control during coast provided by six N2 thrusters on stage 3

Motor: Alliant Techsystems Orion 38 (XL uses same stage 3 as standard Pegasus)
Length: 2.08 m
Diameter: 0.965 m
Mass at ignition: 893 kg
Propellant: solid
Propellant mass: 771 kg
Thrust: 34.31 kN vac average, 38.69 kN vac max
Total impulse: 2.18 MNs
Burn time: 63.8 s
Attitude control: motor nozzle flexing provides pitch/yaw control during powered flight; roll control and 3-axis control during coast provided by six N2 thrusters in two modules

The HAPS Hydrazine Auxiliary Propulsion System is an optional stage carried to improve injection accuracy and performance by about 36 kg for 720 km, 82o. It occupies the payload adapter interior, replacing the N2 tank of the 3-stage version. The attitude jets are supplied instead from two high pressure (395 atm) N2 tanks on the adapter's outer surface.
Thrusters: three fixed blowdown monopropellant Olin Aerospace MR-107s
Propellant: hydrazine
Propellant mass: 72.6 kg
Thrust: each 222 N vac
Burn time: typically 2 burns of 131 + 110 s
Attitude control: nitrogen jets + differential firing of main thrusters

127 kg 2-piece composite fairing, which also covers stage 3 and the avionics packages (and stage 4 when carried), is jettisoned during stage 2 burn. The payload may remain attached to stage 3 or separated by clamp, following pointing to ±2o accuracy or spin-up. On the ground, air-conditioning maintains 21 ±5oC.
Payload volume: 1.17 m diameter, 2.13 m long for 3-stage; 1.76 m or 1.79 m long when HAPS carried
Acceleration load: 8 g longitudinal maximum at end of stage 1 burn (lighter payloads can exceed 8 g during stage 3 burn)

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