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greg goebel (gvgoebel@earthlink.net) / public domain
* VECTORS is an original newsletter of fact and commentary on aerospace, technology, science, and historical topics.
* SOLOVYEV (AVIADVIGATEL) D-20P / D-30 / D-30K TURBOFANS: The first Soviet
turbofan to go into operation was the Solovyev (now Aviadvigatel / "Aircraft
Engine") "D-20P". This was a two-spool engine, with a three-stage fan;
eight-stage HP compressor; a cannular combustion chamber with twelve flame
tubes; a single-stage HP turbine; and a two-stage LP turbine. It included
inlet de-icing using hot bleed air, and a fire extinguishing system. MTO
thrust was 52.96 kN (5,400 kgp / 11,905 lbf). It went into service with the
twin-engine Tupolev Tu-124 airliner in 1962.
SOLOVYEV (AVIADVIGATEL) D-20P TURBOFAN:
_____________________ ____________________ ____________________
spec metric english
_____________________ ____________________ ____________________
diameter 97.6 centimeters 3 feet 2.3 inches
length 3.304 meters 10 feet 10 inches
dry weight 1,468 kilograms 3,236 pounds
thrust (MTO) 52.96 kN / 5,400 kgp 11,905 lbf
thrust (cruise) 10.79 kN / 1,100 kgp 2,425 lbf
pressure ratio 13:1
bypass ratio 1
TSFC (MTO) 20.4 mg / N-s 0.72 lb / lb-h
TSFC (cruise) 25.5 mg / N-s 0.90 lb / lb-h
airflow 113 kg / sec 249 pounds / sec
TWR (MTO) 3.68
fan 3 stage
HP compressor 8 stage
combustor cannular, 12 flame tubes
HP turbine 1 stage
LP turbine 2 stage
starter system electric
_____________________ ____________________ ____________________
The D-30 was introduced into service in the mid-1960s on the Tu-134
twin-engine jetliner, which was refitted with "D-30 Series II" engines in the
early 1970s, featuring a thrust reverser and other improvements.
SOLOVYEV (AVIADVIGATEL) D-30 TURBOFAN:
_____________________ ____________________ ____________________
spec metric english
_____________________ ____________________ ____________________
diameter 1.05 meters 3 feet 5.3 inches
length 3.983 meters 13 feet 1 inch
dry weight 1,550 kilograms 3,417 pounds
thrust (MTO) 66.68 kN / 6,800 kgp 14,990 lbf
thrust (cruise) 12.75 kN / 1,300 kgp 2,866 lbf
pressure ratio 17.4:1
bypass ratio 1
TSFC (MTO) 17.56 mg / N-s 0.62 lb / lb-h
TSFC (cruise) 21.81 mg / N-s 0.77 lb / lb-h
airflow 125 kg / sec 265 pounds / sec
TWR (MTO) 4.39
fan 4 stage
HP compressor 10 stage
combustor cannular with 12 flame tubes
HP turbine 2 stage
LP turbine 2 stage
starter system electric
_____________________ ____________________ ____________________
A downrated version of the D-30K, the "D-30KU-154-11" with 104 kN (10,600 kgp
/ 23,380 lbf) MTO thrust, was developed for the Tupolev Tu-154M three-jet
airliner, also replacing the NK-8s of earlier versions. An uprated version,
the "D-30KP" with 117.7 kN (12,000 kgp / 26,455 lbf) MTO thrust, was
developed for the Ilyusin Il-76 four-jet cargolifter.
SOLOVYEV (AVIADVIGATEL) D-30KU TURBOFAN:
_____________________ ____________________ ____________________
spec metric english
_____________________ ____________________ ____________________
diameter (max) 1.56 meters 5 feet 1.4 inches
diameter (inlet) 1.464 meters 4 feet 9.6 inches
length 5.7 meters 18 feet 8.4 inches
dry weight 2,650 kilograms 5,842 pounds
thrust (MTO) 108 kN / 11,000 kgp 24,250 lbf
thrust (cruise) 27 kN / 2,750 kgp 6,063 lbf
pressure ratio 20:1
bypass ratio 2.42
TSFC (MTO) 13.88 mg / N-s 0.49 lb / lb-h
TSFC (cruise) 19.83 mg / N-s 0.70 lb / lb-h
airflow 269 / sec 593 pounds / sec
TWR (MTO)
fan 3 stage
HP compressor 11 stage
combustor cannular, 12 flame tubes
HP turbine 2 stage
LP turbine 4 stage
starter system pneumatic
_____________________ ____________________ ____________________
Length and weight specifications are with thrust reverser.
The original basic civil "NK-8-4" was a two-shaft turbofan, with a two-stage fan with an attached two-stage LP booster; a six-stage HP compressor; an annular combustion chamber with 139 burners; a single-stage HP turbine; and a two-stage LP turbine. A thrust reverser was apparently an option. MTO thrust was 99.1 kN (10,100 kgp / 22,273 lbf), though this was later uprated to 103 kN (10,500 kgp / 23,150 lbf). The NK-8-4 was the original engine for the Ilyushin Il-62 four-jet airliner.
The downrated "NK-8-2", with 93.2 kN (9,500 kgp / 20,950 lbf) MTO thrust, was
used on early versions of the Ilyushin Il-154 three-jet airliner. The early
Il-154s were later reengined to uprated "NK-8-2U" engines with the same 103
kN thrust rating as the original NK-8-4. An improved version of the NK-8
series, designated the "NK-86" with 127.5 kN (13,000 kgp / 28,660 lbf) MTO
thrust, was used on the Ilyushin Il-86 four-jet widebody airliner.
SAMARA (KUZNETSOV) NK-8-4 TURBOFAN:
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spec metric english
_____________________ ____________________ ____________________
diameter 1.442 meters 4 feet 8.8 inches
length 5.1 meters 16 feet 9.7 inches
dry weight 2,100 kilograms 4,269 pounds
thrust (MTO) 103 kN / 10,500 kgp 23,150 lbf
thrust (cruise) 27.0 kN / 2,750 kgp 6,063 lbf
pressure ratio 23.22
bypass ratio 1.02
TSFC (cruise) 22.1 mg / N-s 0.78 lb / lb-h
TWR (MTO) 5
fan 2 stage fan with 2 LP boost stages
HP compressor 6 stage
combustor annular, 139 burners
HP turbine 1 stage
LP turbine 2 stage
_____________________ ____________________ ____________________
Length and weight is without reverser.
The Al-25 was introduced in the 1950s and is used on the Yak-40 short-takeoff
transports and, as the "Al-25TL", as the powerplant for the Czech Aero
Vodochody L-39 Albatros trainer.
___________________________________________________________________
IVCHENKO (ZMKB PROGRESS) AL-25 SMALL TURBOFAN:
_____________________ ____________________ ____________________
spec metric english
_____________________ ____________________ ____________________
width 82 centimeters 32.3 inches
height 89.5 centimeters 35.2 inches
length 1.993 meters 6 feet 6.5 inches
dry weight 290 kilograms 639 pounds
MTO thrust 14.71 kN / 1,010 kgp 3,307 lbf
cruise thrust 3.49 kN / 355 kgp 785 lbf
pressure ratio 8
bypass ratio 2
TSFC (MTO) 14.86 mg / N-s 0.56 lb / lb-h
TSFC (cruise) 23.71 mg / N-s 0.837 lb / lb-h
TWR (MTO) 5.18
fan 3 stage
HP compressor 8 stage
combustor annular
HP turbine 1 stage
LP turbine 2 stage
starter system external pneumatic or APU
_____________________ ____________________ ____________________
Bench testing of the smaller Lotarev D-36 began in 1971. It has a dry weight of 1,100 kilograms (2,425 pounds), a bypass ratio of 5.6:1, and an MTO thrust of 63.74 kN (6,500 kgp / 14,330 lbf). It is used on the twinjet Antonov An-72 and An-74 short-takeoff transports and the three-engine Yak-42 airliner.
The bigger Lotarev D-18T was developed after the D-36. The D-18T was introduced into service with the oversized four-jet Antonov An-124 transport in the early 1980s, and was later used on the six-engine An-225 derivative of the An-124.
The engine has a single-stage fan, with 33 titanium blades and a conical
spinner; a seven-stage IP compressor, with variable inlet guide vanes; a
seven-stage HP compressor; an annular combustion chamber with 28 burners; a
single-stage HP turbine with directionally solidified blades; a single-stage
IP turbine; a four-stage LP turbine; and a fan-duct thrust reverser. MTO
thrust is 229.8 kN (23,425 kgp / 51,655 lbf). Service life of the D-18T was
originally very poor, but over time the engine's service life was improved to
levels much more comparable to Western large high-bypass turbofans.
LOTAREV (ZMKB PROGRESS) D-18T HIGH BYPASS TURBOFAN:
_____________________ ____________________ ____________________
spec metric english
_____________________ ____________________ ____________________
fan diameter 2.33 meters 7 feet 7.73 inches
dry weight 4,100 kilograms 9,039 pounds
thrust (MTO) 229.8 kN / 23,425 kgp 51,655 lbf
thrust (cruise) 47.66 kN / 4,860 kgp 10,715 lbf
pressure ratio 27.5:1
bypass ratio 5.7:1
TSFC (MTO) 10.2 mg / N-s 0.360 lb / lb-h
TSFC (cruise) 16.14 mg / N-s 0.570 lb / lb-h
TWR (MTO) 5.71
fan 1 stage, 33 fans
IP compressor 7 stage
HP compressor 7 stage
combustor annular, 28 burners
HP turbine 1 stage
IP turbine 1 stage
LP turbine 4 stage
_____________________ ____________________ ____________________
The company also worked on a more advanced small turbofan, the "Astafan", which was a single-shaft turbofan derived from the Astazou turboprop engine. It does not appear that the Astafan actually entered production, and if it did, it wasn't successful. The Astazou and the Astafan will be described in more detail in a later installment in this series.
* Turbomeca also developed two turbofans in collaboration with other firms. The first, the Adour, was a collaboration with Rolls-Royce for the Jaguar strike fighter program, and has already been discussed. The second, the "Larzac", was a collaboration with SNECMA for the Franco-German Dassault-Dornier Alpha Jet twin-engined trainer program.
Bench testing of the Larzac began in 1972, leading to production in 1977. The Larzac is a two-spool turbofan, with a two-stage fan featuring an intake bullet; a four-stage HP compressor; an annular combustion chamber; a single-stage HP turbine; a single-stage LP turbine; a simple fixed jetpipe; and accessories mounted under the fan case.
The Larzac was designed in a modular fashion for easy maintenance and
produces relatively little noise and emissions. The initial production
"Larzac 04-C6" provides 13.19 kN (1,345 kgp / 2,966 lbf) MTO thrust; while
the "Larzac 04-C20", which went into service in 1984, provides 14.12 kN
(1,440 kgp / 3,175 lbf) MTO thrust. The Larzac does not appear to have been
used on any production aircraft except the Alpha Jet.
TURBOMECA-SNECMA LARZAC 04-06 LIGHT TURBOFAN:
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spec metric english
_____________________ ____________________ ____________________
diameter 60.2 centimeters 23.7 inches
length 1.179 meters 3 feet 10.4 inches
dry weight 290 kilograms 640 pounds
thrust (MTO) 13.19 kN / 1,345 kgp 2,966 lbf
pressure ratio 10.6:1
bypass ratio 1.13:1
TSFC (MTO) 20.1 mg / N-s 0.71 lb / lb-h
airflow 28 kg / sec 62 pounds / sec
TWR (MTO) 4.63
fan 2 stage
HP compressor 4 stage
combustor annular
HP turbine 1 stage
LP turbine 1 stage
_____________________ ____________________ ____________________
* MICROTURBO SMALL TURBOJET ENGINES: The French Microturbo firm was founded in 1961 and initially focused on design and production of starter turbines and auxiliary power units (APUs), then moved on to small turbojets. Microturbo later became part of SNECMA, as did Turbomeca, and in 1994 the Microturbo and Turbomeca became a single division inside the SNECMA group.
The initial Microturbo product offering was the "Noelle" starter turbine, which led to a number of starter / APUs such as the "Emeraude", "Espandon", and "Saphir". The Emeraude led to the company's first turbojet, the small and rock-simple "Eclair", intended for self-launching sailplanes.
The Eclair was almost a Whittle-type engine, with a single-stage centrifugal compressor, a reverse-flow annular combustor, and a single-stage turbine. It had a length of 60.7 centimeters, a height of 31.2 centimeters, and a width of 50.5 centimeters (23.9 by 12.7 by 19.9 inches); a dry weight of 35 kilograms (77 pounds); and a thrust of 0.78 kN (80 kgp / 176 lbf). It appears that it was not throttleable. It was followed by an improved derivative, the "Lynx", and then the "Cougar", which was intended for UAVs, neither of which, it seems, were built in volume if they ever reached production at all.
* The next-generation "TRS 18" turbojet was also originally designed to power self-launched sailplanes, but it proved more successful as a powerplant for UAVs, most notably the Italian Meteor Mirach 100 series and the British Flight Refueling Falconet. Development began in 1973, with the engine receiving certification in 1976.
The general configuration of the TRS 18 is much like that of the Eclair, with a single-stage centrifugal compressor; a reverse-flow annular combustion chamber with ten burners and two igniters; and a single-stage turbine. An electric starter / generator is fitted in the intake bullet, and the engine can be stopped and restarted in flight, though apparently it is not throttleable. It provides 1.13 kN (115 kgp / 254 lbf) thrust.
An uprated variant, the "TRS 18-1" with 1.5 kN (153 kgp / 337 lbf) thrust,
was certificated in 1986. Slightly downrated versions of both the TRS 18 and
TRS 18-1 were built for piloted aircraft, including the Italian twin-jet
Caproni C-22J, an appealing trainer derived from Caproni sailplanes; the
Microjet, another twin-jet trainer built by Microturbo itself; and the Bede
BD-5J single-engine sportplane. None of these aircraft were successful, and
in fact the BD-5J acquired a very bad reputation.
MICROTURBO TRS 18 TURBOJET VARIANTS:
___________________________________________________________________
relative
variant max thrust aircraft notes
___________________________________________________________________
TRS 18 Model 046 0.88 BD-5J 600 W generator
TRS 18 Model 046-1 0.88 Microjet 900 W generator
TRS 18 Model 075 1.00 Falconet,Mirach 100 1,500 W generator
TRS 18 Model 076 1.00 Falconet,Mirach 100 1,500 W generator
TRS 18-1 Model 081 1.28 C-22J,Microjet
TRS 18-1 Model 083 1.28 C-22J,Microjet
TRS 18-1 Model 201 1.33 Mirach 100
TRS 18-1 Model 202 1.28 C-22J
___________________________________________________________________
MIROTURBO TRS 18 MODEL 075 SPECIFICATIONS:
_____________________ ____________________ ____________________
spec metric english
_____________________ ____________________ ____________________
width 30.6 centimeters 12.05 inches
height 34.9 centimeters 13.74 inches
length 57.8 centimeters 22.75 inches
dry weight 37 kilograms 81.5 pounds
thrust 1.13 kN / 115 kgp 254 lbf
TSFC 34.5 mg / N-s 1.22 lb / lb-h
TWR 3.11
compressor 1 stage
combustor reverse flow annular, 10 burners, 2 igniters
turbine single stage
starter system electrical
_____________________ ____________________ ____________________
The initial production TRI 60-1 series engine features a three-stage axial
compressor; an annular combustion chamber; and a single-stage turbine. The
intake bullet contains an accessory gearbox and starter-generator, and the
engine provides 0.5% airflow bleed to drive aircraft systems. The TRI 60-1
is throttleable, with an MTO thrust of 3.5 kN (357 kgp / 787 lbf). In US
service, the engine is designated "J403" in some cases.
___________________________________________________________________
MICROTURBO TRI 60 SMALL TURBOJET VARIANTS:
___________________________________________________________________
relative
variant max thrust aircraft notes
___________________________________________________________________
TRI 60-1 1.00 Sea Eagle
TRI 60-2 1.06 Streaker,RBS-15
TRI 60-3 1.14 C.22
TRI 60-5 1.26 Streaker,Skua,Lakshya
TRI 60-30 1.57 Apache,Scalp,Storm Shadow
___________________________________________________________________
MICROTURBO TRI 60-1 SPECIFICATIONS:
_____________________ ____________________ ____________________
spec metric english
_____________________ ____________________ ____________________
diameter 33 centimeters 13 inches
length 74.9 centimeters 29.5 inches
dry weight 47 kilograms 103.6 pounds
thrust 3.5 kN / 357 kgp 787 lbf
pressure ratio 4:1
TSFC 34.5 mg / N-s 1.22 lb / lb-h
airflow 6.2 kg / sec 13.4 pounds / sec
TWR 7.6
compressor 3 stage
combustor annular
turbine 1 stage
starter system options for electrical, cartridge, etc.
_____________________ ____________________ ____________________
TO BE CONTINUED.
* US BOOSTER RENEWAL EFFORTS -- DELTA III / DELTA IV / ATLAS V: NASA Administrator Dan Goldin's entry into office was followed by efforts to revive the space station, planetary exploration, satellite technology -- as well as space launch capability.
As with much of the rest, the effort to develop improved space launch capabilities did not really start with Goldin. The destruction of Challenger had derailed, permanently, the idea that the space shuttle was going to be America's one-stop solution for launching payloads into space, and led to a resurgence in production of expendable boosters. However, the existing large expendable US boosters of the time -- the Delta, the Atlas, the Titan -- still left something to be desired, particularly in terms of cost. The worst example was the Titan IV, which provided the US with a heavy-lift space launch capability at several times the cost-per-kilogram of other boosters.
Of course, since new boosters were a matter of concern to both NASA and the military, collaborating was sensible, though as usual it proved troublesome. NASA and the military tried to hash out a cooperative effort to build improved boosters under the "Advanced Launch System (ALS)" effort in the late 1980s, but coming to an agreement on requirements proved impossible and ALS was abandoned.
The need didn't go away, however. In 1991, US Vice President Dan Quayle revived ALS as the "National Launch System (NLS)", pushing NASA and the Air Force to join hands on development of a family of new boosters that would be modular and scalable, with different assemblies of modules used to launch different classes of payloads. Unfortunately, the US Congress was not enthusiastic about NLS, refusing to authorize adequate levels of funding and then axing the program completely in 1992.
The need still didn't go away, of course, and no sooner had NLS been canned than studies began for a third attempt to build a new generation of expendable boosters. In 1994, this led to the establishment of the "Evolved Expendable Launch Vehicle (EELV)" program, a more conservative approach to NLS that would develop a modular, scalable family of expendable launchers based on existing US boosters. The Air Force took ownership of the EELV program, though the boosters developed by the program would have to also satisfy NASA requirements. In parallel, NASA was to to take ownership of a program to develop a "Reusable Launch Vehicle (RLV)", which was to be more or less a replacement for the space shuttle for NASA and military use. The RLV effort is discussed in a later section.
In response to a USAF request for proposals in 1995, McDonnell Douglas submitted a proposal for a "Delta IV" series of boosters as a follow-on to their existing Delta booster family. Lockheed Martin similarly submitted a proposal for an "Atlas V" series of boosters. The original intent was to select a single vendor, but the Air Force decided to encourage competition and awarded production contracts for both the Delta IV and the Atlas V in 1998.
* McDonnell Douglas had been improving the Delta booster family in the meantime, flying the first "Delta III" in 1998. The Delta III was an incremental improvement on the well-proven Delta II, featuring what amounted to a Delta II first stage with some modest improvements, but with improved solid-rocket boosters; a new and larger 4 meter (13 feet 1 inch) payload fairing; and in particular a new second stage, featuring an improved RL10B-2 version of the Pratt & Whitney RL10 engine, long used on the twin-engine Centaur upper stage.
The Delta III was merely an incremental step. The Delta IV was a big step forward, in fact such a big step that using the "Delta" name was merely cosmetic, as the new booster family was largely new technology.
The central component of the Delta IV family is the "Common Booster Core (CBC)", an entirely new first stage, which by itself is as tall as a complete Delta III and has a diameter of 5 meters (16 feet 3 inches), twice as wide as a Delta II first stage. Its only real connection to the older Delta boosters is use of construction techniques developed for the Deltas.
The CBC features an entirely new LOX-LH2 engine, the Rocketdyne "RS-68", the first major large engine developed since the shuttle SSME. The RS-68 has its ancestry in the SSME, but at 2,892 kN (295,000 kgp / 650,000 lbf) thrust it is 65% more powerful than the SSME, and also has 93% fewer parts than the SSME. Obviously the pain endured during SSME development taught Rocketdyne useful lessons. The RS-68 is gimbaled as were earlier Delta engines, but unlike the earlier powerplants it uses turbopump exhaust for roll control, eliminating the need for separate vernier engines.
Five different primary Delta IV models have been defined. Of course, as with the earlier Deltas, users can "mix and match" various features such as types and numbers of solid rocket boosters, types of upper stages, and types of payload fairings. However, all the upper stages are variations of the Delta III upper stage with the single RL10B-2 engine, which at least establishes one link with the older Deltas. The five members of the Delta IV family include:
Initial flight of the Delta IV was on 20 November 2001, when a Delta IV Medium Plus with two solid-rocket boosters and a 4 meter fairing put the Eutelsat W5 geostationary comsat into orbit. By this time, the booster was the Boeing Delta IV, since Boeing had bought out McDonnell Douglas in the meantime.
* The Lockheed Martin Atlas V was almost as big a departure from its ancestry. As with the Delta IV, Lockheed Martin had been working on improvements outside of the EELV program, beginning development of an interim booster, the "Atlas III", in 1995.
The major change from the earlier Atlas boosters was that the Atlas III adopted a Russian-built engine, an evolution that would have been completely astonishing to the original designers of the booster. The Soviets had developed a very powerful four-chamber LOX-kerosene engine for the Energia project, designated the "RD-170", and also built a two-chamber derivative, the "RD-180", with a thrust of 2,600 kN (265,300 kgp / 585,000 lbf).
The Atlas III uses a single RD-180, supplied by a partnership between Pratt & Whitney and the RD-Amross concern of Russia, with the new propulsion scheme eliminating the classic Atlas "half-stage" configuration. The Atlas III was otherwise similar to its immediate Atlas ancestors, with similar payload fairings, upper stages, solid rocket boosters, and the like.
That was not true of the Atlas V. The Atlas V retained the RD-180 engine but junked almost everything else from the Atlas family, even the old "balloon" tank scheme, developing a new "Common Core Booster (CCB)", wider and longer than the old Atlas main stage, and with far fewer parts. Other options included new, more powerful Aerojet solid rocket boosters; second stages with one or two Centaur engines; and a range of payload fairing options, up to a fairing 23.5 meters (77 feet) long.
Lockheed Martin was required by the terms of the EELV contract to develop an "Atlas V Heavy" booster that would gang three CCBs, but the Air Force focused procurement of EELVs on the Boeing Delta IV, and Lockheed Martin determined that the company would lose money on the Atlas V Heavy. After discussions with the USAF, Lockheed Martin was allowed to discontinue development of the Atlas V Heavy.
The first Atlas V was launched on 22 August 2002, putting the Eutelsat Hot Bird 6 geostationary comsat into orbit. Although Lockheed Martin had got the short end of the stick on orders from the Air Force, in mid-2003 the USAF decided to cancel a significant portion of the Delta IV order with Boeing, as the company had been caught in what was judged unfair business practices, and switched the orders to Lockheed Martin Atlas Vs.
* US BOOSTER RENEWAL EFFORTS -- PEGASUS / TAURUS / MINOTAUR: Well before EELV became a reality, the US had flown a new solid-fuel booster, the Orbital Sciences Corporation (OSC) Pegasus, a winged, air-launched, solid-fuel booster that in its original configuration could put 375 kilograms (825 pounds) into low Earth orbit.
OSC had been founded in 1982 by three Harvard Business School graduates who had worked on a class project in the commercialization of space. After graduation, they developed a small solid fuel upper stage, the "Transfer Orbit Stage (TOS)" for the NASA shuttle program. Having cut their teeth on this project, they went on to the more ambitious Pegasus, using company funds along with support from DARPA.
The idea for the Pegasus was derived from the Vought F-15-launched ASAT interceptor tested in the 1980s. The initial Pegasus design had a launch weight of about 18,600 kilograms (41,000 pounds). It had three stages, all of them solid-fuel, though a fourth storable liquid-fuel stage could be added. The airframe was made most of graphite-epoxy composites, with triangular wings mounted in the middle of the airframe and a conventional aircraft-type tail. Aerodynamic flight control was provided by the tail surfaces, since the wing had no control surfaces. The wing had an ablative layer of cork on the bottom to soak up atmospheric friction heating.
Air launch was seen as attractive because a booster launched at altitude has to plow through less of the atmosphere, and also gets a slight kick from the velocity of its launch platform. The flight profile taken by a winged booster is also gentler, and so the Pegasus did not have to be built as sturdily as a ground-launched booster. Finally, the booster could be launched from a wide range of locations, with the specific location chosen as most convenient for the mission requirements.
First launch of the Pegasus was on 5 April 1990. Initial launches of the Pegasus were with the old NASA B-52A, which had been originally acquired for the X-15 program. Later on, OSC acquired a Lockheed L-1011 Tristar jumbo jet and modified it to launch the Pegasus. The Tristar was given the name "Stargazer".
There were nine Pegasus launches into 1998, with eight being successful. The basic Pegasus was then completely phased out in favor of the "Pegasus XL", which was stretched and had more powerful first and second stages, allowing it to put 450 kilograms (1,000 pounds) into low Earth orbit. There were 21 launches of the Pegasus XL from 1994 into the summer of 2000, with three failures.
* In 1994, OSC introduced another member of the family, the "Taurus", which was a ground-launch booster consisting, essentially, a Pegasus XL without flight surfaces mounted on top of, initially, an MX ICBM main stage, designated "stage 0" to allow OSC to retain the traditional stage 1 / 2 / 3 nomenclature of the Pegasus upper stages. Stage 0 was quickly changed to a Thiokol Castor-120 stage, similar to the MX stage but with milder acceleration characteristics.
Taurus was developed by another collaboration between OSC and DARPA, with DARPA focused on a vehicle that could launch military payloads on short notice. It is substantially more powerful than the Pegasus XL, with the ability to put 1,400 kilograms (3,100 pounds) into low Earth orbit. There were six launches of the Taurus from 1994 to September 2001, including commercial launches, with one failure.
The Taurus was a demonstration of OSC's ability to "mix and match" different existing rocket stages to construct a new class of booster, and in 2000 the company flew another variation on the Taurus theme, the "Minotaur", or "Minuteman-Taurus", which featured the first two stages of the Minuteman ICBM, both stages being refurbished from retired Minutemen, and the second two stages from the Pegasus XL. The Minotaur can put up to 635 kilograms (1,400 pounds) into low Earth orbit.
The Minotaur is definitely a niche product, however. It was developed under the Air Force "Orbital / Suborbital Program (OSP)" to launch suborbital missile-defense targets and small military payloads. It is not intended for launch of commercial payloads, as the US Congress, in an effort to protect commercial booster development, put strong restrictions on the use of refurbished military missiles, or their components, for spacecraft launch.
* OSC has proven something of a success story in the commercial space business with their boosters and ambitious other projects, some of which will be described later. Other companies have tried to develop new small boosters and not met with similar success. Lockheed Martin built their own three/four stage ground-launch booster based on the Castor-120, named the "Athena" (originally the "Lockheed Launch Vehicle / LLV" and then the "Lockheed Martin Launch Vehicle / LMLV"), but it has only been flown a handful of times and is clearly less profitable than the Pegasus family, if it's profitable at all.
Other attempts to develop low-cost expendable launch vehicles during the 1990s went nowhere slowly or went bust. Although OSC has been enterprising, it is worth remembering that their booster strategy has been generally supported by government funding from DARPA, NASA, and the Air Force, and that is not a business model that can support a breakthrough in space commercialization along the lines of the Internet revolution.
* US BOOSTER RENEWAL EFFORTS -- DC-X / X-33 / X-34: In parallel with developments such as Pegasus, work continued on the elusive goal of reusable launch vehicles (RLVs).
Alongside the dead-end NASP effort, the Strategic Defense Initiative Organization had been interested in building a single-stage-to-orbit rocket reusable rocket vehicle to put SDIO payloads into orbit. After a sequence of studies and proposals, in August 1991 the SDIO awarded McDonnell Douglas a contract to build the "Delta Clipper Experimental (DC-X)" demonstrator vehicle. The "Clipper" in the name called back to the Clipper flying boats of the 1930s and 1940s, which pioneered international commercial passenger travel, and the DC-X was seen as a stepping stone to technologies that could similarly open up space travel to a wider audience.
The DC-X was completed in an amazingly short time, performing its first flight on 18 August 1993. It was strictly a demonstration vehicle and was not designed to perform flights anywhere near the threshold of space. It was instead meant to demonstrate enabling technologies for an operational vehicle, and in particular was to show how a space vehicle could be operated in a fashion similar to that of a commercial airliner, with modest support needs and a quick turnaround.
The DC-X was unmanned, and was a blunt, four-sided wedge about 12.2 meters (40 feet) tall. It launched and landed vertically on a set of four retractable landing legs, and was powered by four RL-10A5 LOX-LH2 engines, like those used on the Centaur upper stage. The Strategic Defense Initiative was pretty much dead by the time the first flight took place, and only three flights were conducted before the effort ran out of money.
Dan Goldin found the effort very interesting, however, and stepped in to rescue the program in January 1994. NASA went on to fund an improved and slightly larger version, the "DC-XA", also known as the "Clipper Graham", after Lieutenant General Daniel O. Graham, who had helped push through the original DC-X program. The DC-XA performed its first flight in the spring of 1996, but on 31 July 1996, on its fourth flight, it failed to extend a landing leg, tipped over, and exploded.
* By this time NASA had established a more formal RLV program that was pursuing two new experimental vehicles, the large "X-33" and the small "X-34".
There was strong industrial competition for the X-33 effort. McDonnell Douglas proposed a "Delta Clipper" vehicle that was effectively a scaled-up operational DC-X. Rockwell International submitted a design that resembled an unmanned version of the shuttle and, like it, took off vertically and landed horizontally. Lockheed Martin submitted a lifting body design that would also take off vertically and land horizontally, and featured an unorthodox "aerospike" engine concept.
Lockheed Martin won the competition, partly because its design was the most daring. The aerospike engine to be used by the X-33 would not have an external bell like that of a conventional rocket engine, instead simply having a central "spike", with the atmosphere providing thrust confinement. This in theory allowed efficient exhaust performance through the entire flight profile, in contrast to a fixed bell exhaust, which was optimized for only one segment of the flight.
The X-33 was to be a demonstrator, not an operational vehicle. It was hopefully to be followed by a scaled-up full operational vehicle, which eventually emerged on paper as the Lockheed Martin "VentureStar". The NASA plan assumed that the commercial sector would bear a considerable portion of the development costs, in return for a guaranteed set of government payload launches.
There was some skepticism over the X-33 from the outset. The X-33, as an SSTO vehicle, was up against the same obstacle that killed NASP: it required an extremely low empty weight that suggested extensive use of "unobtanium". Officials involved with the X-33 program also felt a need to be cautious about the prospects of building an operational follow-on vehicle, since they remembered the "voodoo economics" that were used to sell the shuttle and didn't want to make the same mistake again.
That was one the reasons to build the demonstrator: prove the idea and then take it from there. Had the shuttle program started off with a demonstrator, it might have gone a bit more smoothly.
* The X-34 program got off to a shaky start. Originally, it was defined as air-launched like the Pegasus, though it was to be reusable and have a liquid-fuel engine. OSC and Rockwell International collaborated on the original proposal, but NASA was proposing that full development be heavily supported by company funds, and the financial analyses of the accountants on the OSC / Rockwell side showed that it wouldn't pay off.
NASA swallowed their irritation over this, then recast the effort in a program to build a smaller and less ambitious suborbital demonstrator that would be built by OSC. NASA officials admitted that the original concept had been overly ambitious, since it was focused on a design for an operational system when a proof-of-concept vehicle was what was needed. First flight was scheduled for 1998.
* US BOOSTER RENEWAL EFFORTS -- COMMERCIAL PROJECTS: While the Air Force and NASA worked on their own new launch technologies, a number of commercial startups were also pursuing new expendable booster and RLV designs during the 1990s.
Beal Aerospace promoted the "BA-2", which was basically a "big dumb booster", designed to be as cheap as possible and completely expendable. It was to have three stages, a height of about 107 meters (236 feet), and a lift capacity of 5,800 kilograms (12,800 pounds) into geostationary orbit. It was to be built mostly of composite materials and would use simple, cheap pressure-fed engines.
The Kistler Aerospace Corporation "K-1", in contrast, was to use conventional LOX-kerosene propulsion, provided by Russian-built engines, but it was to be fully reusable, with its two stages guiding themselves back to a recovery area and landing with parachutes and airbags. Kistler hoped to be able to turn around a K-1 for relaunch in only two weeks.
The K-1 was sort of a simple, direct approach to an RLV. One of the more exotic other approaches was the "Roton", which was to be an "orbital helicopter". The Roton was to be an egg-shaped vehicle with four straight narrow wings sticking out from its sides. Each wing was tipped by a rocket engine.
On takeoff, the wings, actually rotor blades, would be turned so they were flat to the ground. The rockets would spin the blades and the vehicle would take off like a helicopter. Since the vehicle would be using lift instead of raw thrust, it would be actually relatively efficient. It would also be relatively quiet and could use simple launch facilities. Finally, the rotating rockets would generate a siphon effect that would draw propellant into them without using heavy, expensive turbopumps.
As the Roton ascended and the air grew thinner, the blades would generate less and less lift, and the rockets would be turned so that they provided direct thrust. The rotor would have to kept spinning to keep up the siphon effect, but only a slight amount of the total thrust would be required. On reentry, the vehicle would be mostly empty, and the rotors would provide an effective drag brake to allow the vehicle to hover down to a soft landing.
Another interesting scheme was promoted by Kelly Space & Technology, in which an RLV would be towed to high altitude by a Boeing 747, and then released to blast into orbit. The RLV could carry a heavy payload on a suborbital mission, or launch an expendable second stage to put a payload into low Earth orbit.
A third commercial RLV scheme was promoted by Pioneer Rocketplane Corporation, in which an RLV would take off in a mostly unfueled state from a normal runway using twin turbofan engines. The RLV would then top off with liquid oxygen from a tanker flying at high altitude. Once refueled, the RLV would then blast into orbit on rocket power.
All these ideas were very interesting, but the history of attempts to build commercial launchers to that time was dismal. Orbital Sciences was a significant exception to the long list of failures, but OSC was technologically conservative and closely tuned to the needs of the company's government clients. If the company's founders had broad visions of opening up the space frontier to business and the citizenry, they had clearly categorized them as a long-term matter.
* RUSSIAN SPACE IN RAPID DECLINE: In the early and mid-1990s, the US space program seemed to be undergoing a rejuvenation of sorts. The same could not be said about the Russian space program.
The collapse of the Soviet Union did lead to a consolidation of most of the often competing factions trying to run the civil space program into the single Russian Space Agency (RSA, or RKA in its Russian acronym), initially under Yuriy Koptev. It did have to deal with the Military Space Forces (MSF, or VKS in its Russian acronym), as well as the Energiya technical-industrial organization, the consolidated heir to Korolyev's original OKB-1 and the source, directly or indirectly, for Russian space technology.
Early on, the Energiya organization acted as though it was independent of the RKA, but after the privatization of Energiya in 1993 RKA managed to assert control over the award of government contracts and show Energiya just who the boss was. The RKA also had to deal with a number of other space-related organizations, such as the Moscow Academy of Science's Institute for Space Research (IKI in its Russian acronym), but in the bankrupt funding environment IKI and its like were mostly nonfunctional.
It wasn't like the RKA and the Russian space effort was overfunded, either. There was little money to pay for such basic things as facilities maintenance and salaries, and essentially the only people hanging on were the old experienced hands, in their 60s and 70s, who had no other place to go. There was attrition among these folk of course, some of them dropping out to find work elsewhere and some of them dying, and the knowledge base of the organization was gradually eroding.
In April 1995, Mir cosmonauts asked what the function of a device found on the station might be. After considerable hunting around, the people on the ground were forced to answer that nobody remembered and there was no record of it. This was not quite as extraordinary as it sounded, since anyone who has ever worked for a large industrial organization anywhere knows the long-term archiving of information can be surprisingly haphazard, but it still suggested the decay in the program.
The physical decay of the main civil launch center at Baikonur was obvious to anyone who visited it. Both the technical infrastructure and the living facilities for those who worked there were wretched. Homes lacked heat and reliable power, social services were sketchy, and the shelves of stores were bare.
The tracking ships that had supported the Soviet manned space program -- the KOMAROV, KOROLYEV, and GAGARIN -- ended up rusting at dock in Odessa since there was no money to operate them. The Soviets had launched the Altair / Luch comsats, their answer to the US TDRSS, to provide a space-based communications network for the station and other space missions, but for various reasons it was not an entirely satisfactory replacement. In fact, Mir cosmonauts would often end up relying on their amateur radio gear for communications.
The main ray of hope for the Russian space effort was the quality of the boosters that were developed during the Soviet era. The Proton, Soyuz, and other rockets were thoroughly developed, very reliable and capable, and highly competitive with launchers from other nations. There was the question of finding the funding to even keep the launchers in production, and that meant finding foreign partners.
In 1994, the Russian Khrunichev organization formed an alliance with Lockheed, soon to be Lockheed Martin, in the US, to sell and fly both American and Russian boosters. The "International Launch Services (ILS)" company was to prove very successful, and even give the Russian partners in the venture funds to work on improvements to the vehicles.
The partnership with NASA that was signed in 1993 also provided some hope for the Russian manned space program. By Russian standards, the funds NASA provided were generous. However, life remained grim in the Russian space program. On 16 November 1996, a Russian Proton booster launched the "Mars 96" probe, a highly ambitious Mars mission, built with considerable European assistance, featuring an orbiter that would drop two small landers and two surface penetrator probes onto the planet. Mars 96 never made orbit, an upper stage failure dropping it onto South America or in the Pacific Ocean to the west. It was a bitter thing, all the more so because the loss of the mission was due to a booster failure, and Russian boosters had a well-deserved reputation for reliability.
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