Made by Orbital Sciences Corporation, the Pegasus XL launcher is the first commercially developed
space launch system. The
Pegasus is a three-
stage winged
rocket weighing approximately 23,130 kg without
payload, and measuring 16.9 m in
length, 1.5 m in
diameter and 6.7 m as of
wingspan. It is
dropped from a Stargazer L-1011
aircraft at an
altitude of about 38,000 ft and at a
speed of about 235 m/s (845 km/h, 525 mph,
pick your favorite units) and falls for about 5 seconds before its first stage rocket (Orion 50S XL motor, 43,586 kNs of
specific impulse) sends it on an
arched
trajectory. After about 76 s, the first stage is
jettisoned, and stage two ignites soon after (Orion 50S motor, 11,218 kNs). Stage three (Orion 38 motor, 2,185 kNs) ignites after 400 to 600 seconds of
flight. During the pull-up
maneuver,
centripetal acceleration can reach up to 3.7 g.
Depending on the desired orbital parameters and launch location (which can be either California, Virginia, Florida, the Canary Islands or the Marshall Islands), the Pegasus XL rocket can launch a 425 kg payload on a 200 km low earth orbit, or a 125 kg payload on a 1400 km orbit. Payload is delivered in only 8 to 11 minutes to the desired orbit due to the rocket's initial speed and altitude.
Since 1996, Pegasus rockets conducted 30 successful missions, sending more than 70 satellites into orbit. Pegasus also happens to be the first winged vehicle to reach a speed of Mach 8. Before 1997 though, there was at least 5 failures; two of them beign called failures because the payload was delivered outside the 3-sigma normal dispersion range.
Primary source: www.orbital.com