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Delta II 7000 Series |
DELTA
II 7000 SERIES Fact Sheet
Written and Edited by Cliff Lethbridge
Classification: Space Launch
Vehicle
Length: 128 feet
Diameter: 8 feet
The version of Delta II launch vehicles currently in use, the Delta II 7000
Series improved performance by employing new solid rocket boosters.
Lightweight Hercules (later Alliant Techsystems) Graphite Epoxy solid rocket
boosters, larger and more powerful than previously employed Castor solid rocket
boosters, improved the overall vehicle thrust. The solid rocket boosters are
called Graphite Epoxy Motors (GEM).
Each GEM is 42 feet, 6 inches long and has a diameter of 3 feet, 4 inches.
Each GEM burns HTPB solid fuel. The GEM's ignited on
the ground, or "ground-lit" GEM's, can each
produce a thrust of about 112,200 pounds. The GEM's
ignited in the air, or "air-lit" GEM's, can
each produce a thrust of about 116,100 pounds.
A Rocketdyne first stage engine can produce a
liftoff thrust of about 200,000 pounds. Like previous Delta variants, the first
stage burns a combination of liquid oxygen and RP-1 (kerosene) liquid fuel.
An Aerojet second stage engine burns a combination
of nitrogen tetroxide and Aerozine-50 liquid fuel.
The second stage engine can produce a thrust of about 9,815 pounds. Several
Delta II 7000 Series rockets are available with two stages only, and are used
for carrying payloads into low-Earth orbit.
Payload capability of the two-stage variants depends on the number of GEM's employed and the size of the payload fairing, which
is offered in diameters of 9 feet, 6 inches or 10 feet. The heaviest payloads
can be carried using the smaller, lighter payload fairing.
The Delta II 7320 employs three GEM's and with the
9-foot, 6-inch diameter payload fairing can carry a maximum 6,320-pound payload
to low-Earth orbit.
The Delta II 7420 employs four GEM's and with the
9-foot, 6-inch diameter payload fairing can carry a maximum 6,970-pound payload
to low-Earth orbit.
The most powerful of the two-stage Delta II 7000 Series rockets, designated
Delta II 7920, employs nine GEM's and can carry an
11,330-pound payload to low-Earth orbit using the 9-foot, 6-inch payload
fairing.
A number of three-stage versions of the Delta II 7000 series are available
to meet diverse mission applications. All of the three-stage variants employ a
Thiokol solid-fueled third stage that can produce a thrust of about 14,920
pounds.
As with the two-stage variants, performance of the three-stage Delta II 7000
Series rockets depends upon the number of GEM's
employed and the size of the payload fairing, which is offered in diameters of
9 feet, 6 inches or 10 feet. The heaviest payloads can be carried employing the
smaller, lighter payload fairing.
The Delta II 7325 employs three GEM's, and with
the 9-foot, 6-inch diameter payload fairing can carry a maximum 2,210-pound
payload to geostationary transfer orbit or a maximum 1,615-pound payload to
Earth-escape trajectory.
The Delta II 7425 employs four GEM's, and with the
9-foot, 6-inch diameter payload fairing can carry a maximum 2,490-pound payload
to geostationary transfer orbit or a maximum 1,770-pound payload to
Earth-escape trajectory.
The Delta II 7925 employs nine GEM's, and with the 9-foot, 6-inch diameter payload fairing can carry a maximum 4,120-pound payload to geostationary transfer orbit or a maximum 2,900-pound payload to Earth-escape trajectory.
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