Orbital Sciences Corp. / US Air Force Pegasus Pegasus-H Pegasus XL
Overall
Vehicle
Operational from 05.04.1990 03.04.1995 27.06.1994
  to 03.08.1994 09.10.2000 13.06.2021
Orbital flights   6 4 35
Payload weight t LEO 0.455 LEO 0.455 LEO 0.544
Gross liftoff weight t 19.20 19.20 22.65
Gross propellant weight t 16.02 16.02 19.78
Total length m 15.43 15.43 16.94
Max. diameter (span) m 6.71 6.71 6.71
Total liftoff thrust (s.l.) kN 500 500 647.5
Total impulse (vac) MN*s 46.0 46.0 56.8

Fairing

Total length m 4.41 4.41 4.41
Diameter m 1.27 1.27 1.27
Total weight t 0.17 0.17 0.17

Stage 4

Name   (HAPS) (HAPS) (HAPS)
  Length m 0.71 0.71 0.71
Diameter m 0.40 0.40 0.40
Liftoff weight t ? ? ?
Propellant weight t 0.072 0.072 0.072
Engines   MR-107N (3) MR-107N (3) MR-107N (3)
Propellant   Hydrazine Hydrazine Hydrazine
Total thrust (vac) kN 0.67 0.67 0.67
Specific impulse (vac) N*s/kg 2265 2265 2265
Burn time s 245 245 245
Total impulse (vac) MN*s 0.16 0.16 0.16
Stage 3

Name

  Orion 38 Orion 38 Orion 38
  Length (+Avionic) m 1.34 (1.76) 1.34 (1.76) 1.34 (1.76)
Diameter m 1.27 (0.96) 1.27 (0.96) 1.27 (0.96)
Liftoff weight (+Ad.. Av.) t 1.180 1.180 1.180
Propellant weight t 0.771 0.771 0.771
Engines   ATK ATK ATK
Propellant   solid HTPB solid HTPB solid HTPB
Total thrust (vac) kN 32.2 (av) 32.2 (av) 32.2 (av)
Specific impulse (vac) N*s/kg 2834 2834 2834
Burn time s 67.7 67.7 67.7
Total impulse (vac) MN*s 2.18 2.18 2.18

Stage 2

Name   Orion 50 Orion 50 Orion 50XL
  Length m 2.04 (2.85) 2.04 (2.85) 2.19 (3.00)
Diameter m 1.27 1.27 1.27
Liftoff weight t 3.379 3.379 4.342
Propellant weight t 3.025 3.025 3.924
Engines   ATK ATK ATK
Propellant   solid HTPB solid HTPB solid HTPB
Total thrust (vac) kN 114.6 (av) 114.6 (av) 160.6 (av)
Specific impulse (vac) N*s/kg 2865 2865 2855
Burn time s 75.6 75.6 69.7
Total impulse (vac) MN*s 8.7 8.7 11.2

Stage 1

Name   Orion 50S Orion 50S Orion 50SXL
  Length m 8.98 8.98 10.34
Diameter m 1.27 1.27 1.27
Liftoff weight t 14.020 14.020 16.386
Propellant weight t 12.163 12.163 15.024
Engines   ATK ATK ATK
Propellant   solid HTPB solid HTPB solid HTPB
Total thrust (s.l.) kN 500.0 (max) 500.0 (max) 647.5 (max)
Specific impulse (s.l.) N*s/kg 2590 2590 2591
Burn time s 75.3 75.3 69.1
Total impulse (vac) MN*s 35.0 35.0 43.3