NASA HL-20

from Wikipedia, the free encyclopedia
1: 1 model of the HL-20

HL-20 (HL for Horizontal Lander and the serial numbering 20) was a project of the US space agency NASA to develop a manned reusable space glider at the Langley Research Center and within NASA's Personnel Launch System (PLS) studies in the 1980s and to Beginning of the 1990s. HL-20 should use the principle of the lifting body for re-entry and atmospheric flight . In addition to extensive aerodynamic studies, full-scale models were also made to a. to optimize the interior design, and flight simulator tests carried out. Airworthy prototypes were not built, but since 2005 with the Dream Chaser a spaceship has been developed on the direct basis of research work and in the form of the HL-20.

Development history

HL-20 is in a long series of US attempts with lifting bodies. One of the direct predecessors is the Northrop HL-10 . In terms of the external shape, the NASA M2-F1 , Northrop M2-F2 , Northrop M2-F3 , Martin-Marietta X-23 and the Martin-Marietta X-24A should also be mentioned

In the course of various NASA projects and studies, the HL-20 developed from a pure lifting body test vehicle to the HL-20 PLS, the Personnel Launch System , a space glider for transporting people into space and back.

Soviet influence

BOR-4 at the MAKS 2005

In addition to our own findings and research on the US side, mutual espionage was also the order of the day during the Cold War . Research into lifting bodies was also carried out in the Soviet Union. For example, the MiG-105 Spiral project from the 1960s is worth mentioning . In the case of HL-20, they were images of a Soviet test with a re-entry vehicle on June 4, 1982. An Australian P-3 Orion sea ​​reconnaissance aircraft was able to observe the recovery of the Soviet model BOR-4 (Kosmos 1374) in the Indian Ocean. Top secret photo and video recordings of this incident were made on both sides. The recordings have now been approved and are now also accessible on the Internet.

The photos, which the Australian Navy handed over to the CIA and finally to NASA, showed the US space experts a form of lifting body, the design of which, in their opinion, had excellent properties for a space glider. With this knowledge and further investigations, the shape of BOR-4 flowed into the design of HL-20.

Aerodynamic studies

Wind tunnel model (1988)

Part of the HL-20 development included extensive aerodynamic studies. The result was large amounts of research. In addition to computer analyzes, wind tunnel tests up to Mach 20 were carried out. The design showed very good natural trim and stability properties.

In 1991 it was reported that in the course of the development of the last two years the glide ratio in the subsonic range had been increased from 3.2 to 4.2.

During the flight simulations it was determined that only 13.6 kg of the maneuver engine reaction mass is required for normal re-entry. With a shifted focus and strongly differing conditions in the upper atmosphere, 90.7 kg was calculated as the maximum amount. A specially created flight simulator allowed pilots to simulate the final approach with a sidestick and to prove the controllability and precision landing ability. It was used by pilots who were already familiar with other lifting-body aircraft or high-speed aircraft such as the X-15 . It was determined that a landing speed of approx. 325 km / h (175 kn) is sufficient to land the HL-20 safely and at approx. 550 km / h (200 kn) there is sufficient safety margin for landing in cross winds. Further attempts concerned the proof of the ability to land automatically.

1: 1 model and interior dummy

Interior dummy

In 1990, students at North Carolina State University and North Carolina Agricultural and Technical State University made 1: 1 mock-ups of the exterior and interior. The Langley Research Center carried out studies on ergonomics. Among other things, entry and exit scenarios were tested in a horizontal and vertical position. Emergency exit scenarios were also run through. In the vertical starting position, it was planned that the occupants should escape into the open through the hatch that swings up to form a platform and a ladder attached to the inside of the cabin roof. The hatch was located between the pilot and passenger seats. A room of 1.65 m³ (58 cft) was allocated to each of the maximum 10 occupants.

Investigations of the field of vision for the pilots in 1991 showed that there was still a slight need for optimization in the nose area, with no impact on aerodynamics expected.

Personnel Launch System

Investigation of the accessibility in the starting position

For the Personnel Launch System (PLS), NASA examined two different aerodynamic concepts. One requirement was that the PLS should fit into the space shuttle's payload bay. On the one hand, this was the lifting body concept of the HL-20 with folding wings developed in Langley. In contrast, a space capsule concept in the form of a truncated cone was set, which was developed in the Johnson Space Center . It was intended to land the capsule on a paraglider on runners. With a capsule, loads of 3–4 g are common during re-entry, while with HL-20 they could be limited to 1.3–1.5 g. The high glide ratio of the HL-20 also enabled greater flexibility in the selection of the landing site and alternative options.

Building on the PLS studies, Rockwell presented a study on the production-ready design, operation and maintenance with the associated certification processes based on commercial aviation processes at the end of 1992 . Lockheed started a feasibility study in October 1991. Boeing also prepared a contract study.

Three start options were considered for the Personnel Launch System:

  • on the tip of a Titan 4 rocket that is to be qualified for manned use
  • Advanced Launch System
  • Adaptation of liquid fuel-powered boosters that were planned for the space shuttle

In the event that the launch was aborted on the launch pad or immediately after the launch, a rescue system was provided that would take the spaceship away from the rocket and land on a parachute system. For this purpose solid rocket rockets were planned, which should carry HL-20 up to an altitude of about 1.3 km (4,000 ft). At a start z. B. from Cape Canaveral with a trajectory over the Atlantic, a waterfall would then have been practically inevitable and appropriate precautions were taken to keep the rear hatch above water.

The heat shield should be constructed similarly to that of the space shuttle, but one expected significantly less maintenance. This and processes that are based on the work philosophy in commercial aviation should significantly reduce man-hours on the ground. The use of non-toxic rocket fuels , which would make the use of commercial aviation infrastructure, i.e. normal take-off and landing sites , possible without special equipment , was repeatedly emphasized as a further advantage over the existing systems (including space shuttle) . The crew should be able to disembark immediately after landing and access to cargo, such as time-sensitive or surveillance-critical experiments, would have been possible.

Technical specifications

Three-sided view of the HL-20
  • Length: approx. 8.8 m (29 ft)
  • Span: 7.16 m
  • Total weight: between 9,979 kg and approximately 10,900 kg (24,000 lb), depending on the source and level of development
  • Crew and Payload: 2 pilots and 8 passengers with 545 kg (1200 lb) cargo or up to 1,800 kg (4,000 lb) cargo with reduced number of passengers

HL-42 in the Access-to-Space study (1993–1994)

In 1993/1994, the Access to Space Study examined various strategies for the further development of manned US space travel. A main point was to reduce the immense costs of the manned US space flight, which mainly consisted of the space shuttle, and to propose a strategy for the further development of space vehicles. Part of the study was the HL-42 , an enlarged version of the HL-20. The 42 in the name resulted from the 42 percent enlargement of the HL-20 in order to be able to meet the requirements for the transport capacity.

A recommendation of the study was that developments can be implemented more efficiently by industrial partners than by NASA itself. For this was the term "Skunk Works" type approach ( " Skunk Works " approach ) that the on the good experience in the construction U-2 and the SR-71 built, embossed. This paved the way for the further subsequent commercialization of US space travel.

As a result of the study, the greatest long-term savings potential was located in new technologies, which, however, in contrast to the further development of the space shuttle or the implementation of the HL-42 concept, which is considered to be more conventional, required very high initial investments and entailed a high technical risk. The work on the HL-20, as well as the HL-42 concept, was not pursued any further. NASA turned to new projects. This was followed by developments such as the single-stage systems of the Delta Clipper and the Venture Star derived from the X-33 , as well as other projects such as the X-34 . Neither of these projects resulted in an operational spacecraft.

Further development

In the 1990s, NASA was working on the development of a rescue spaceship, the Crew Return Vehicle , for the space station. The lifting body concept was used with the NASA X-38 (1995–2002), albeit with a significantly simplified operational concept. This program was also canceled before the completion of the first space-suitable model.

In 2006, NASA launched the Commercial Orbital Transportation Services (COTS; German " Commercial Transport Services in Earth Orbit") program. This funding program was intended to initiate the transport of equipment, supplies and experiments to and from the International Space Station (ISS) with the help of private companies. With the decommissioning of the space shuttle in 2011, the US temporarily lost its own access to manned space travel and the ability to bring cargo to the ISS itself.

Dream Chaser (from 2005)

Dream Chaser, hanging from a helicopter (2013)

In the run-up to the official start of the COTS program in 2005, SpaceDev announced, after reviewing various spacecraft studies, that it would use HL-20 as a basis for its future spacecraft Dream Chaser . In addition to the right concept, one of the main reasons was that a lot of development work and budget had been flowing into the HL-20 over many years and therefore very detailed data was already available. The following year, SpaceDev acquired the license rights to HL-20 from NASA.

In 2008 SpaceDev was taken over by Sierra Nevada Corporation (SNC) and development of the Dream Chaser continued there. The manned version was developed from 2004 to 2014. In 2011, SNC organized an event to honor the former employees on the HL-20 project. In 2013, the first drop test was carried out with an airworthy prototype in its original size. However, this variant was not considered in the final rounds of tenders for several NASA programs, despite NASA development budgets in the three-digit million range and the often expressed "sympathy bonus". Dream Chaser was the only “real spaceship”, while all other final designs used the space capsule concept. Only the unmanned cargo version, which was presented in 2014 for the Commercial Resupply Services program , received an order from NASA for six cargo flights to the International Space Station from the beginning of the 2020s.

Prometheus (2010-2011)

As part of the NASA CCDev program ( Commercial Crew Development ), in 2010, in addition to SNC, the Orbital Sciences Corporation also applied for the Prometheus , a concept that was also based on the HL-20. Prometheus failed in the tender against the Dream Chaser. Work on it was therefore stopped again the following year.

literature

  • Jim Hodges: The Dream Chaser: Back to the Future . In: ASK magazine . Issue 44, November 2, 2011, p. 24–28 (English, online [PDF; accessed January 1, 2019]).
  • Howard W. Stone and William M. Piland: The HL-20 Lifting-Body Personnel Launch System . In: SAE Transactions . Vol. 100, Section 1: JOURNAL OF AEROSPACE, Part 2 (1991), November 2, 2011, pp. 1955-1968 , JSTOR : 44548056 (English).
  • Carl F. Ehrlich: HL-20 concept - Design rationale and approach . Rockwell International Study. In: Journal of Spacecraft and Rockets . Vol. 30, No. 5, September – October 1993, 1993, pp. 573-581 , doi : 10.2514 / 3.25568 (English).

Web links

Commons : NASA HL-20  - collection of pictures, videos and audio files

Individual evidence

  1. a b c d e f g h HL-20 Model for Personnel Launch System Research: A Lifting-Body Concept. NASA Langley Research Center, June 22, 2011, accessed December 29, 2018 .
  2. General Mikoyan SA: The SPIRAL Orbital Plane and the BOR-4 and BOR-5 Flying Models. (DOC / ZIP; 275 kB) May 26, 2001, accessed on December 29, 2018 (English).
  3. a b 50 years to orbit: Dream Chaser's crazy Cold War backstory. Ars Technica, September 7, 2012, accessed December 25, 2018 .
  4. James R. Asker: NASA Design for Manned Spacecraft Draws on Soviet Subscale Spaceplane . In: Aviation Week & Space Technology . Volume 133, Number 13, September 24, 1990, pp. 28 (English, [behind the registration barrier: http://archive.aviationweek.com/issue/19900924/#!&pid=28 Online] [accessed December 30, 2018]).
  5. a b c d e f g h i j Edward H. Phillips: Langley Refines Design, Begins Human Factors Tests OF Personnel Launch System . In: Aviation Week & Space Technology . Volume 135, Number 2, July 15, 1991, pp. 52–53 (English, [behind registration barrier: http://archive.aviationweek.com/issue/19910715/#!&pid=52 Online] [accessed December 30, 2018]).
  6. ^ Edward H. Phillips: Modified Pilot Simulator Refines HL-20 Handling . In: Aviation Week & Space Technology . Volume 134, Number 24, June 17, 1991, pp. 199 (English, behind the registration barrier: * 1991 flight simulator http://archive.aviationweek.com/issue/19910617/#!&pid=198 [accessed December 30, 2018]).
  7. ^ Carl F. Ehrlich: HL-20 concept - Design rationale and approach . Rockwell International Study. In: Journal of Spacecraft and Rockets . Vol. 30, No. 5, September-October 1993, pp. 573-581 , doi : 10.2514 / 3.25568 (English).
  8. ^ Office of Space Systems Development, NASA Headquarters: Access to Space Study: Summary Report . January 1994, p. 30 (English, online [PDF; accessed December 31, 2018]): “The applicable HL-20 design data base includes extensive NASA […] research, as well as results of contracted studies with Rockwell, Lockheed, and Boeing in defining efficient manufacturing and operations design. "
  9. a b Office of Space Systems Development NASA Headquarters: Access to Space Study: Summary Report . January 1994 (English, 86 pp., Online [PDF; 4.8 MB ; accessed on February 10, 2020]).
  10. Giuseppe De Chiara and Dr. Theodore A. Talay: HL-42 “Personnel & Logistics Vehicle The might have been. (PDF; 5.1 MB) Presentation slides with a summary of the HL-42 concept. June 1, 2013, accessed February 10, 2020 .
  11. ^ A b Private Spacecraft Developer Settles on New Design. Space.com, November 23, 2005, accessed December 25, 2018 .
  12. 50 years to orbit: Dream Chaser's crazy Cold War backstory. Ars Technica, September 7, 2012, accessed December 25, 2018 (English): "In 2006, SpaceDev went on to execute a licensing agreement with NASA to use the HL-20's design for its new Dream Chaser suborbital spacecraft."
  13. NASA Engineers Honored for Past Work's Impact to Future Commercial Space Vehicle Design. June 20, 2011, accessed January 3, 2019 .
  14. Amanda Miller: Dreaming big. 2018, accessed on January 3, 2019 (English, July / August 2018): "SNC won four Commercial Crew Development contracts in all, for a total of $ 363.1 million, to design and build the Dream Chaser test vehicle [...]"
  15. Stephen Clark: NASA splits space station cargo deal three ways. Spaceflight Now, January 14, 2015, accessed December 25, 2018 .
  16. ^ Businesses Take Flight, With Help From NASA. New York Times, January 31, 2011, accessed December 30, 2018 .
  17. ^ Orbital may wind down its commercial crew effort. NewSpace Journal, April 22, 2011, accessed December 30, 2018 .