Ракета-носитель Delta: История и Этапы Развития

Rocket family

The Delta rocket family was a versatile range of American rocket powered expendable launch systems that provided space launch capability in the United States from 1960 to 2024. Japan also launched license built derivatives (N I, N II, and H I) from 1975 to 1992. More than 300 Delta rockets were launched with a 95% success rate. The series was phased out in favor of the Vulcan Centaur, with the Delta IV Heavy rocket's last launch occurring on April 9, 2024.

The original Delta rockets used a modified version of the PGM 17 Thor, the first ballistic missile deployed by the United States Air Force (USAF), as their first stage. The Thor had been designed in the mid 1950s to reach Moscow from bases in Britain or similar allied nations, and the first wholly successful Thor launch had occurred in September 1957. Subsequent satellite and space probe flights soon followed, using a Thor first stage with several different upper stages. The fourth upper stage combination of the Thor was named the Thor "Delta", reflecting the fourth letter of the Greek alphabet. Eventually the entire Thor–Delta launch vehicle came to be called simply "Delta". NASA intended Delta as "an interim general purpose vehicle" to be "used for communication, meteorological, and scientific satellites and lunar probes during 1960 and 1961". The plan was to replace Delta with other rocket designs when they came on line. From this point onward, the launch vehicle family was split into civilian variants flown from Cape Canaveral, which bore the Delta name, and military variants flown from Vandenberg Air Force Base (VAFB), which used the more warlike Thor name. The Delta design emphasized reliability rather than performance by replacing components that had caused problems on earlier Thor flights; in particular, the trouble prone inertial guidance package made by AC Spark Plug was replaced by a radio ground guidance system, which was mounted to the second stage instead of the first. NASA made the original Delta contract to the Douglas Aircraft Company in April 1959 for 12 vehicles of this design:
Stage 1: Modified Thor IRBM with a Block I MB 3 engine group consisting of one Rocketdyne LR 79 main engine and two Rocketdyne LR 101 vernier thrusters for roll control, producing a total of thrust, including LOX/RP1 turbopump exhaust. Stage 2: Modified Able. Pressure fed UDMH/nitric acid powered Aerojet AJ 10 118 engine producing This reliable engine cost US$4 million to build and is still flying in modified form today. Gas jet attitude control system. Stage 3: Altair. A spin stabilized (via a turntable on top of the Able) at 100 rpm by two solid rocket motors before separation. One ABL X 248 solid rocket motor provided of thrust for 28 seconds. The stage weighed and was largely constructed of wound fiberglass. These vehicles would be able to place into a LEO or into GTO. Eleven of the twelve initial Delta flights were successful, and until 1968, no failures occurred in the first two minutes of launch. The high degree of success achieved by Delta stood in contrast to the endless parade of failures that dogged West Coast Thor launches. The total project development and launch cost came to US$43 million, US$3 million over budget. An order for 14 more vehicles was made before 1962.

From 1969 through 1978 (inclusive), Thor Delta was NASA's most used launcher, with 84 launch attempts. (Scout was the second most used vehicle with 32 launches.) Satellites for other government agencies and foreign governments were also launched on a cost reimbursable basis, totaling 63 satellites. Out of the 84 launch attempts there were 7 failures or partial failures, a 91.6% success rate. The Delta was a launch success, but it has also been a significant contributor to orbital debris, as a variant used in the 1970s was prone to in orbit explosions. Eight Delta second stages launched between 1973 and 1981 were involved in fragmentation events between 1973 and 1991 usually within the first 3 years after launch, but others have broken apart 10 or more years later. Studies determined that explosions were caused by propellant left after shutdown. The nature of the propellant and the thermal environment occupied by the derelict rockets made explosions inevitable. Depletion burns were started in 1981, and no fragmentation events for rockets launched after that have been identified. Deltas launched before the 1970s variant have had fragmentation events as long as 50 years after launch.

The Delta II series was developed after the 1986 Challenger accident and consisted of the Delta 6000 series and 7000 series, with two variants (Lite and Heavy) of the latter. The Delta 6000 series introduced the Extra Extended Long Tank first stage, which was 3.66 m longer, and the Castor 4A boosters. Six SRBs ignited at takeoff, and three ignited in the air. The Delta 7000 series introduced the RS 27A main engine, which was modified for efficiency at high altitude at some cost to low altitude performance, and the lighter and more powerful GEM 40 solid boosters from Hercules. The Delta II Med Lite was a 7000 series with no third stage and fewer strap ons (often three, sometimes four) that was usually used for small NASA missions. The Delta II Heavy was a Delta II 792X with the enlarged GEM 46 boosters from Delta III.

As part of the Air Force's Evolved Expendable Launch Vehicle (EELV) program, McDonnell Douglas / Boeing proposed Delta IV. As the program name implied, many components and technologies were borrowed from existing launchers. Both Boeing and Lockheed Martin were contracted to produce their EELV designs. Delta IVs were produced in a new facility in Decatur, Alabama. The first stage changed to liquid hydrogen fuel. Tank technologies derived from Delta III upper stage, but widened to 5 metres. The kerosene engine replaced with Rocketdyne RS 68, the first new, large liquid fueled rocket engine designed in the United States since the Space Shuttle Main Engine (SSME) in the 1970s. Designed for low cost, it had lower chamber pressure and efficiency than the SSME, and a much simpler nozzle. Thrust chamber and upper nozzle was a channel wall design, pioneered by Soviet engines. Lower nozzle was ablatively cooled. The second stage and fairing were taken from the Delta III in smaller (Delta IV Medium) models; widened to 5 metres in Medium+ and Heavy models. Medium+ models had two or four GEM 60, solid boosters. The plumbing was revised and electrical circuits eliminated need for a launch tower. The first stage was referred to as a Common Booster Core (CBC); a Delta IV Heavy attached two extra CBCs as boosters.