Hypersonic Air-Launching Option (HALO) spaceplane

[Vahe231991]

I bought a copy of Scott Lowther's bookazine Lockheed SR-71 Blackbird: Origins and Evolution last summer, and on pages 123-124 there is an entry about the proposed Hypersonic Air-Launching Option (HALO) hypersonic aircraft, along with  drawings of the HALO on page 125. The HALO was conceived by the NASA Ames Research Center in Silicon Valley as a less risky alternative to the X-30/NASP program, intended for air-launch from an SR-71 Blackbird at 80,000 feet. It was powered by a scramjet engine beneath the fuselage and a linear aerospike rocket engine at the chopped-off rear end of the fuselage, and after release from the SR-71, it would ignite its rocket engine in order to reach Mach 9 at 140,000 feet and eventually run  on scramjet power for two minutes, descending to around 100,000 feet while attaining Mach 10. Like the X-15, the HALO would have glided back to earth to a horizontal landing, and the HALO's nose was similar to that of the final design iteration of the X-30/NASP in being platypus-shaped. Despite being seen by NASA Ames as having less development risk than the NASP given that the latter ran into developmental problems, the HALO concept didn't reach the hardware phase.

Link:
https://www.secretprojects.co.uk/threads/national-aerospace-plane-nasp-x-30.250/page-2

[AmigaClone]

I bought a copy of Scott Lowther's bookazine Lockheed SR-71 Blackbird: Origins and Evolution last summer, and on pages 123-124 there is an entry about the proposed Hypersonic Air-Launching Option (HALO) hypersonic aircraft, along with  drawings of the HALO on page 125. The HALO was conceived by the NASA Ames Research Center in Silicon Valley as a less risky alternative to the X-30/NASP program, intended for air-launch from an SR-71 Blackbird at 80,000 feet. It was powered by a scramjet engine beneath the fuselage and a linear aerospike rocket engine at the chopped-off rear end of the fuselage, and after release from the SR-71, it would ignite its rocket engine in order to reach Mach 9 at 140,000 feet and eventually run  on scramjet power for two minutes, descending to around 100,000 feet while attaining Mach 10. Like the X-15, the HALO would have glided back to earth to a horizontal landing, and the HALO's nose was similar to that of the final design iteration of the X-30/NASP in being platypus-shaped. Despite being seen by NASA Ames as having less development risk than the NASP given that the latter ran into developmental problems, the HALO concept didn't reach the hardware phase.

Link:
https://www.secretprojects.co.uk/threads/national-aerospace-plane-nasp-x-30.250/page-2

Is there any clue when that proposal was made?

The reason for the question relates to the M21 (a modified A12 - which was the basis for the SR-71) collision with a D21 drone after a failed launch of the same on 30 July 1966.

Any proposal that involved launching a drone (or crewed aircraft for that matter) from a M21 or modified SR-71 after that date might not have received as much support as previously.

[libra]

You have a point. Orient Express was announced in Reagan state of the union adress in 1986, so 20 years to the day after the D-21 collision.

[Whisper-stream]

NASA was looking at the SR-71 as a potential mothership for experimental hypersonic vehicles as early as 1971, when the agency requested a feasibility study from Lockheed's Skunk Works. Lockheed engineers Henry G. Combs and John R. McMaster ultimately submitted the results of a study on the feasibility of mounting the HT-4 (a subscale model of a NASA concept for a high-speed transport) on the Blackbird. They examined both dorsal and ventral mounting options, separation methods, and launch and landing profiles. Combs and McMaster recommended wind tunnel studies to determine launch parameters, as well as development of operating restrictions to avoid exceeding the Blackbird's structural load limits. Required structural modifications to the Blackbird would have included hardpoints for mounting the launch pylon and fuel system modifications for controlling aircraft center-of-gravity.

The HT-4 would have been about 50 feet in length, more than 7 feet longer than the D-21. It was to be powered by a Pratt & Whitney RL-10 engine, and (like the D-21) was designed to be launched at standard Blackbird cruise and altitude conditions. Although the Lockheed study declared the concept technically feasible, Kelly Johnson noted that he wished to "talk to NASA about safety aspects before concrete action is taken to implement any construction."

[Vahe231991]

I bought a copy of Scott Lowther's bookazine Lockheed SR-71 Blackbird: Origins and Evolution last summer, and on pages 123-124 there is an entry about the proposed Hypersonic Air-Launching Option (HALO) hypersonic aircraft, along with  drawings of the HALO on page 125. The HALO was conceived by the NASA Ames Research Center in Silicon Valley as a less risky alternative to the X-30/NASP program, intended for air-launch from an SR-71 Blackbird at 80,000 feet. It was powered by a scramjet engine beneath the fuselage and a linear aerospike rocket engine at the chopped-off rear end of the fuselage, and after release from the SR-71, it would ignite its rocket engine in order to reach Mach 9 at 140,000 feet and eventually run  on scramjet power for two minutes, descending to around 100,000 feet while attaining Mach 10. Like the X-15, the HALO would have glided back to earth to a horizontal landing, and the HALO's nose was similar to that of the final design iteration of the X-30/NASP in being platypus-shaped. Despite being seen by NASA Ames as having less development risk than the NASP given that the latter ran into developmental problems, the HALO concept didn't reach the hardware phase.

Link:
https://www.secretprojects.co.uk/threads/national-aerospace-plane-nasp-x-30.250/page-2

Is there any clue when that proposal was made?

The reason for the question relates to the M21 (a modified A12 - which was the basis for the SR-71) collision with a D21 drone after a failed launch of the same on 30 July 1966.

Any proposal that involved launching a drone (or crewed aircraft for that matter) from a M21 or modified SR-71 after that date might not have received as much support as previously.

The HALO design was a 1990s proposal. It would have been a manned hypersonic aircraft combining the linear aerospike system similar to that of the X-33 and VentureStar with the scramjet of the X-30/NASP.

[Hog]

M-21 breakup-Narrated by Kelly Johnson

[Vahe231991]

I bought a copy of Scott Lowther's bookazine Lockheed SR-71 Blackbird: Origins and Evolution last summer, and on pages 123-124 there is an entry about the proposed Hypersonic Air-Launching Option (HALO) hypersonic aircraft, along with  drawings of the HALO on page 125. The HALO was conceived by the NASA Ames Research Center in Silicon Valley as a less risky alternative to the X-30/NASP program, intended for air-launch from an SR-71 Blackbird at 80,000 feet. It was powered by a scramjet engine beneath the fuselage and a linear aerospike rocket engine at the chopped-off rear end of the fuselage, and after release from the SR-71, it would ignite its rocket engine in order to reach Mach 9 at 140,000 feet and eventually run  on scramjet power for two minutes, descending to around 100,000 feet while attaining Mach 10. Like the X-15, the HALO would have glided back to earth to a horizontal landing, and the HALO's nose was similar to that of the final design iteration of the X-30/NASP in being platypus-shaped. Despite being seen by NASA Ames as having less development risk than the NASP given that the latter ran into developmental problems, the HALO concept didn't reach the hardware phase.

Link:
https://www.secretprojects.co.uk/threads/national-aerospace-plane-nasp-x-30.250/page-2

Is there any clue when that proposal was made?

The reason for the question relates to the M21 (a modified A12 - which was the basis for the SR-71) collision with a D21 drone after a failed launch of the same on 30 July 1966.

Any proposal that involved launching a drone (or crewed aircraft for that matter) from a M21 or modified SR-71 after that date might not have received as much support as previously.

I've attached a drawing of the Hypersonic Air-Launching Option (HALO) project for convenience.

The book The X-43A Flight Research Program: Lessons Learned on the Road to Mach 10 (of which a PDF file is available here) explains on pages 38 to 40 how the HALO concept would have worked:

Despite the rejection of an incremental development approach for NASP, various subscale proposals were still made over the years. The most ambitious was the hypersonic air-launch option (HALO). This was a Dryden proposal for a piloted vehicle launched from the back of an SR-71. The HALO concept and the flight plan reflected Dryden’s experiences with rocket planes since the late 1940s. The influence of Dryden’s past was apparent in the HALO’s planned mission profile, which was similar to that of the X-15 of the 1960s.

The profile called for the SR-71/HALO to take off from Edwards and fly to the Boise, Idaho, area. The launch would be made at Mach 3 and 70,000 feet. The HALO would be boosted to test speeds – from Mach 8 to Mach 10 – by a liquid hydrogen-fueled RL-10 rocket engine. The nose of the vehicle was detachable, so the ramp angle of the inlet could be altered according to the tests being made. Different modular scramjet engine designs would be fitted to the HALO’s underside. The engines would be tested during a two-minute cruise at test conditions. During this period, the scramjet’s response to variations in the angle of attack and sideslip, as well the effects of different yaw, pitch, and roll rates. The results from each of the scramjet designs could then be compared. Once the speed run was completed, the HALO would pitch up to reduce dynamic pressure and heating on the vehicle. The HALO would glide south across Utah, then make a sweeping turn across California before landing back at Edwards.

The goal was to show that scramjets could operate at varying conditions, could avoid unstarts, and could operate while maneuvering. In addition, the profile would test different injector designs. Data on the physics of hypersonic flight, such as the real gas, catalytic, and boundary layer effects would be collected, and the thermal protection system also would be tested. About 50 to 100 flights would be made during the program.

To keep costs down, off-the-shelf equipment such as actuators, landing gear systems, and the pilot’s ejection seat would be used. The RL-10 rocket engine was well proven and very reliable as evidenced from its use in the Centaur upper stage. Costs to build the HALO were very roughly estimated by Dryden engineers at around $300 million. To refine this further, Ben Rich of Lockheed’s Skunk Works was asked by Dryden managers to review the HALO design, assess its feasibility, and provide a cost estimate for the vehicle.

[tyrred]

I bought a copy of Scott Lowther's bookazine Lockheed SR-71 Blackbird: Origins and Evolution last summer, and on pages 123-124 there is an entry about the proposed Hypersonic Air-Launching Option (HALO) hypersonic aircraft, along with  drawings of the HALO on page 125. The HALO was conceived by the NASA Ames Research Center in Silicon Valley as a less risky alternative to the X-30/NASP program, intended for air-launch from an SR-71 Blackbird at 80,000 feet. It was powered by a scramjet engine beneath the fuselage and a linear aerospike rocket engine at the chopped-off rear end of the fuselage, and after release from the SR-71, it would ignite its rocket engine in order to reach Mach 9 at 140,000 feet and eventually run  on scramjet power for two minutes, descending to around 100,000 feet while attaining Mach 10. Like the X-15, the HALO would have glided back to earth to a horizontal landing, and the HALO's nose was similar to that of the final design iteration of the X-30/NASP in being platypus-shaped. Despite being seen by NASA Ames as having less development risk than the NASP given that the latter ran into developmental problems, the HALO concept didn't reach the hardware phase.

Link:
https://www.secretprojects.co.uk/threads/national-aerospace-plane-nasp-x-30.250/page-2

Is there any clue when that proposal was made?

The reason for the question relates to the M21 (a modified A12 - which was the basis for the SR-71) collision with a D21 drone after a failed launch of the same on 30 July 1966.

Any proposal that involved launching a drone (or crewed aircraft for that matter) from a M21 or modified SR-71 after that date might not have received as much support as previously.

I've attached a drawing of the Hypersonic Air-Launching Option (HALO) project for convenience.

The book The X-43A Flight Research Program: Lessons Learned on the Road to Mach 10 (of which a PDF file is available here) explains on pages 38 to 40 how the HALO concept would have worked:

Despite the rejection of an incremental development approach for NASP, various subscale proposals were still made over the years. The most ambitious was the hypersonic air-launch option (HALO). This was a Dryden proposal for a piloted vehicle launched from the back of an SR-71. The HALO concept and the flight plan reflected Dryden’s experiences with rocket planes since the late 1940s. The influence of Dryden’s past was apparent in the HALO’s planned mission profile, which was similar to that of the X-15 of the 1960s.

The profile called for the SR-71/HALO to take off from Edwards and fly to the Boise, Idaho, area. The launch would be made at Mach 3 and 70,000 feet. The HALO would be boosted to test speeds – from Mach 8 to Mach 10 – by a liquid hydrogen-fueled RL-10 rocket engine. The nose of the vehicle was detachable, so the ramp angle of the inlet could be altered according to the tests being made. Different modular scramjet engine designs would be fitted to the HALO’s underside. The engines would be tested during a two-minute cruise at test conditions. During this period, the scramjet’s response to variations in the angle of attack and sideslip, as well the effects of different yaw, pitch, and roll rates. The results from each of the scramjet designs could then be compared. Once the speed run was completed, the HALO would pitch up to reduce dynamic pressure and heating on the vehicle. The HALO would glide south across Utah, then make a sweeping turn across California before landing back at Edwards.

The goal was to show that scramjets could operate at varying conditions, could avoid unstarts, and could operate while maneuvering. In addition, the profile would test different injector designs. Data on the physics of hypersonic flight, such as the real gas, catalytic, and boundary layer effects would be collected, and the thermal protection system also would be tested. About 50 to 100 flights would be made during the program.

To keep costs down, off-the-shelf equipment such as actuators, landing gear systems, and the pilot’s ejection seat would be used. The RL-10 rocket engine was well proven and very reliable as evidenced from its use in the Centaur upper stage. Costs to build the HALO were very roughly estimated by Dryden engineers at around $300 million. To refine this further, Ben Rich of Lockheed’s Skunk Works was asked by Dryden managers to review the HALO design, assess its feasibility, and provide a cost estimate for the vehicle.

This is... Just how would a pilot even work in this jalopy?

[CameronD]

That's what the ejection seat is for.  To bale out at the earliest opportunity.

To keep costs down, off-the-shelf equipment such as actuators, landing gear systems, and the pilot’s ejection seat would be used.

[Vahe231991]

I found this illustration of the HALO design from a January 1993 issue of Popular Mechanics, and it will give you a visual idea of how the HALO would have flown in action after piggyback launch from an SR-71.