When I gave Part 1, last week, as a talk in 1963 or 64 to the Scientific Society at my old school, repeated to the Ayr squadron of the Air Training Corps, the X-15 programme at Edwards Air Force Base in California was in full swing. Martin Caidin’s book Wings into Space (Holt, Rinehart and Winston,1964) gave ‘the History and Future of Winged Space Flight’ (Figs. 1 and 2), Scott Crossfield’s autobiography Always Another Dawn gave the story of the X-15’s development, operational experience with it had been described by Robert M. White (‘Higher than Man Ever Was: Story by X-15’s Pilot’, Life, 12th September 1960), and by Joseph A. Walker in the National Geographic Magazine (‘I Fly the X-15, Half Plane, Half Missile’, September 1962). Aldous Huxley, living under the flight path in southern California, wrote in praise of it for one of the UK colour supplements, but I haven’t been able to trace that.
Interestingly, Figs. 1 and 2 show different stages of the project. Wilf Hardy’s painting, which I’ve seen used to advertise the book, shows the prototype X-15 fitted with two X-1 rocket engines for early flight tests, before the big XLR-99 engine was installed for the research programme. On the book jacket, the X-15 has ‘NASA’ added on the tail, and extra fuel tanks for an experimental ramjet which was flown as a dummy but never fired up.
In Always Another Dawn, Crossfield described a proposal to put a flat-bottomed, delta-winged X-15B into orbit with a cluster of Navaho boosters (Figs. 3 and 4). “We were under orders not to discuss it beyond the confines of our secret workshop… if we did, the men in white coats would come after us”. The liquid-fuelled engine of the Navaho booster was also used for the first generation of the Atlas missile (see ‘Launcher Development’, ON, 19th November 2023), so the idea wasn’t all that crazy. There was a less ambitious plan for the X-15B to be launched on suborbital flights from the XB-70 supersonic bomber (Fig. 5), and that merged into design work for the orbital Boeing X-20 Dyna-Soar (see below). Ironically the XB-70 itself was to claim the life of an X-15 pilot in June 1966, when Joe Walker collided with it in an F-104 Starfighter during a publicity flight for North American Aviation (Fig. 6; James R. Hansen, First Man: the Life of Neil Armstrong, Simon & Schuster, 2005.)
It’s not often realised that Britain was still a contender at this stage. British interest in High Test Peroxide dated back to torpedo propellant tests in 1924, and in the intense competition with the USA, Russia and France to poach German talent and hardware at the end of the war, British teams were comparatively successful with the Walter aircraft and submarine development teams at Peenemünde and Kiel (J. Hazelwood, ‘German Rocket Engineers at Farnborough’; S. Reddin, lecture, ‘Capture and Exploitation of Walterwerke, Kiel’, British Rocketry Oral History Programme, 2006.) The technology was applied in the RAF’s Blue Steel, an air-launched, rocket-powered, hydrogen peroxide-fuelled Mach 3 cruise missile which was the core of the British independent nuclear deterrent from 1963 to 1970. Studies of rocket fighters began in 1949, and in 1953 the RAF issued an Operational Requirement for a Mach 2 rocket fighter with a ceiling of 100,000 feet and a ‘get-you-home’ jet engine, to be armed with two Firestreak air-to-air missiles (Fig. 7, © A. S. Ruth, Wikimedia Commons, 2008. Note the holes bored in the speed brakes, “which were otherwise too powerful”).
Its mission would be to intercept incoming Soviet bombers over the North Sea. Saunders-Roe Ltd. gained the contract to build three SR-53 prototypes (one later cancelled). By August 1955 ‘US interest’ had materialised with $1.5 million investment, and the first aircraft was rolled out in June 1956. Its de Havilland Spectre 1A motor burned High Test Peroxide and kerosene with 7.5 minutes endurance, with considerable input from German technology, including lorries and storage tanks “nicked from Peenemünde”. The aircraft could reach 60,000 feet in 3.5 minutes, or 160,000 feet “if you lost control of it at the top, which was the tricky bit.” (H. Matthews, A. Wood, The Saga of SR 53, HPM Publications, Beirut (1999). At 160,000 feet there could be real problems, because it had no thrusters for attitude control at that height – see comments on the A4B, and the X-15 fatality, in Part 1.
Flight testing began at Boscombe Down in May 1957, ending in October 1959, after the loss of one aircraft on takeoff with the death of Squadron leader John Booth. The Ministry of Supply issued a contract in September 1956 for 27 SR-177 aircraft, 9 for development, 9 for the RAF and 9 for Royal Navy carrier operations (Fig. 8), with a larger jet engine (Fig. 9). But the programme was overshadowed by a White Paper, ‘An Outline of Future Policy’, issued by Minister of Defence Duncan Sandys in April 1957, which announced that all manned fighter projects after the English Electric Lightning were to be cancelled in favour of guided missile development. No fewer than seven supersonic projects went down soon afterwards, including the Avro 720, another rocket aircraft (W. Green, “Supersonic Scrapheap”, RAF Flying Review, XVII, 1, 1960). At first the SR-177 was exempted because of its naval rôle, but it too was cancelled in December that year, and a potential order from West Germany fell through.
As a last-ditch effort to save the aircraft Saunders-Roe proposed building three SR-177s for research purposes, including a version for hypersonic research, to be air-launched from a Valiant or Vulcan bomber. Suitably redesigned, it could have explored the same speed and altitude range as the X-15. Young people of the time were led to expect that Britain would have a leading rôle: for instance Haunted Hangers, a 1960 boys’ novel by George E. Rochester, depicted a secret aerospace plane in which ‘the blue-clad officers and men of the Royal Air Force’ would go ever higher and faster, eventually reaching other worlds (Hutchinson, London (1960). In real life, many key personnel from the cancelled UK projects moved to Canada to work on the F105 Avro Arrow, and when that too was cancelled under pressure from the USA, many of them were recruited to work for the new NASA agency, and held top positions until the end of the Space Shuttle era. (George Abbey, Eric Brown, Joe Engle and Reginald Turnill (Chair): discussion, ‘Test Flying’, UK Space Conference, Charterhouse School, March 2008; D. Miller, Shoda Memorial Lecture, ‘A Historical Review of Pratt & Whitney Canada”, University of Glasgow, 16th May 2007; George Abbey, Charles Martin Lecture, ‘The Contribution of Britons to NASA’., BROHP 9th Annual Conference ‘Space Really Matters’, 2007.)
The sequel to the X-15 was to have been the Boeing X-20 Dyna-Soar (short for Dynamic Soaring, Fig. 10) whose name somehow got past an administration not known for its sense of humour in these matters. After the mildly boring names given to the Project Mercury capsules, the Gemini astronauts were forbidden to attach names to their spacecraft after Virgil Grissom called his The Unsinkable Molly Brown, in reference to the loss of his Liberty Bell 7 at sea. Dyna-Soar was a surprisingly whimsical name for a project which employed 10,000 people at its end, with $2 billion already spent. The name might have generated accusations that the project represented outmoded military thinking, because the much-vaunted object of inspecting other nations’ satellites in space seemed all too easy to counter with proximity fuses and booby-traps. Martin Caidin saw it as simply a bid by the Air Force to retain a human presence in space with winged vehicles, in case a need for them arose (Rendezvous in Space, Dutton, 1964 – Fig. 11).
The original concept was a boost-glide system, but if launched by a Titan IIIC booster (Fig. 12), it had “no place to land unless it went right around the Earth”. After air-drops from the NASA B-52 there was a plan for sub-orbital launches on the Titan II, with very large fins to counter the aerodynamic forces generated by the payload (Fig. 13), to land on downrange islands or in Brazil – developing a large cross-range capability was “a key reason for the programme”, for Inter-Operational Capability in military trials, to fly undisclosed weapons systems on much larger vehicles later. The large rocket motor (Fig. 14) would be discarded before atmosphere entry (Fig. 15), and the vehicle would land on skids like the X-2, with wire brushes at the rear.
Neither Titan II nor Titan III could put the X-20 into orbit, which would require a Saturn I, which had fins already, though they’d need to be enlarged (Fig. 16). Showing film of his Apollo 13 mission at the ‘View from Earth 1984’ seminar in Big Bear Lake, James Lovell said, “Poor Dr. von Braun couldn’t design a rocket without fins. It’s an appendage, like a bow tie.” But in fact the Saturn fins had two important rôles: to balance the aerodynamic pressures of the escape towers on the vehicles, and to hold them down while building thrust for launch – something given much more attention since Viking 4 ripped itself out of the test stand and took to the air in what was supposed to be a static firing (Milton W. Rosen, The Viking Rocket Story, Faber & Faber, 1956). The Titan-Gemini combination had no escape tower because its weight plus the compensating fins would have made it too heavy. Instead the crew had ejector seats, so powerful that if they were used, the astronauts might never walk again – no small factor in Walter Schirra’s decision not to eject from Gemini 6 after its premature engine shut-down. At the Smithsonian Air & Space Museum’s hypersonics history symposium in 1990, William (Bill) Lamar said that the X-20 design evolved in a context of 30-40% booster failure rate, which “wasn’t a nice thing to do to the astronaut”, and atmosphere entry from a launch abort would have generated an unacceptable g-load, so the Dyna-Soar had both an escape rocket and an ejector seat. A planned 1000 lb of research instrumentation would reduce Dyna-Soar’s payload still more.
Boeing favoured a Hot Structure approach, and a competing proposal from Bell advocated liquid cooling. Coming in to atmosphere at a very low angle, 0.75°, the temperature would nevertheless reach 4000° on the nose-cone, which would be made of graphite with zirconium rods and iridium fasteners, and would change shape due to expansion, while the underside would be made of molybdenum, with a chromium underbody. Six basic lifting bodies (half-cones with flattened wings on the bottom) called ASSET were launched from Cape Canaveral on Thor missiles (retrieved from RAF bases in East Anglia – see ‘Launcher Development’) to test the new exotic materials in flight, with interchangeable panels made by different companies, and water coolant instead of insulation.
Bill Lamar was Boeing’s chief of new bomber design, and with the X-20 his philosophy was “to go where the other guy couldn’t go without economically feeling the pain”, and as Napoleon said, ‘Meet the enemy’. At first there was big Congressional support, but the X-20 fell victim to oscillation in aims – military v non-military, orbital v. sub-orbital, with time and money wasted on evaluating the different configurations and sub-systems on different boosters. 15 air-launches were planned (4 of them powered), to be followed by two unmanned orbiters and 8 manned missions; but the programme was cancelled in December 1963, just before glide tests were due to begin. The atmosphere flight control system and Reaction Control System for attitude control in space were passed on to the Space Shuttle, but otherwise, in the view of X-15 and Shuttle pilot Joe Engle, 20 years’ worth of development was lost (‘Test Flying’, above).
The late Prof. Terence Nonweiler, (see Part 1) considered that the design philosophy and materials technology of the US space programme took a wrong turn with the cancellation of the Dyna-Soar, leaving it wedded to an approach for which his kindest word was ‘pragmatic’. Under pressure to beat the Russians, the Man in Space programme had begun with the question, “What’s an easy engineering shape to build?” ‘A cone.’ “Does it fly?” ‘Yes.’ (A 1986 exhibit at the Johnson Space Centre confirmed that the Mercury capsule originally was conical.) “If we truncate it to save weight, will it still fly?” ‘Yes.’ “If we make it biconic to save weight, will it still fly?” ‘Yes…’ And to fly on the existing Redstone and Atlas boosters, it had to be made of aluminium, so it had to have a ceramic heat shield on the blunt end, borrowing both technologies from the ICBM programmes. But once development had taken that line, the pressure of the race meant it had to be followed with Gemini, and then with Apollo, going back to the truncated cone, though in both the mass distribution was altered to give some aerodynamic control during atmosphere entry (Lectures, ‘The Apollo 13 Disaster’, Hamilton, April 1970; ‘The Future of the Space Shuttle’, Glasgow University Union, November 1973.).
The original lifting bodies were all half-cones. The first, the M1, a half-cone with trailing edge flaps, would be stable on atmosphere entry only down to Mach 6, and have problems with heating on the fins. The M2 had a flattened afterbody to allow trimming (Fig. 17); with fins added, it acquired a boat-tail like the early Nonweiler Waveriders (see ‘Waverider’, ON, November 27th 2022). A rear flap and elevons were added for pitch control, and after wind-tunnel tests at NASA Ames Research Center, the ‘F’ designation was added for flight models. The M2-F1 was built of wood, for tow launches; the M2-F2 was thought to have enough stability with upper surface flaps alone, a philosophy which Gordon Ross, the head of ASTRA’s Waverider project, later called “opening doors in the side of it”. The spectacular crash at the beginning of The Six Million Dollar Man happened when the pilot, Bruce Peterson, pulled up the M2-F2 to avoid a helicopter which got in the way while filming the landing, leaving him insufficient time to lower the undercarriage. Ross believes the accident may also have involved an elevator stall, a nasty event which cost the life of British test pilot Mike Lithgow, when it happened to the prototype BAC-111 airliner.
Two families of lifting bodies emerged, with the same XLR-11 rocket engine used in the X-1 and subsequent rocket aircraft, up to the first X-15. NASA Ames favoured ones with flat tops, like the M2-F2, HL-10 and SV-5P, later renamed X-24A (Fig. 18), while Martin and the Langley Research Center developed flat-bottomed ones. The Martin M-103 lifting body developed into the SV-5 (Space Vehicle-5), with aluminium body and ceramic heat shield, three of which were launched on Atlas boosters from Vandenburg Air Force Base into the Pacific in the PRIME project (Precision Recovery Including Manoeuvring Entry). The third PRIME mission was retrospectively named the X-23A, and the SV-5P manned vehicle became the X-24A, modified into the X-24B as a test vehicle for the Space Shuttle (Fig. 19). In basic shape the Space Shuttle was a lifting body, though with wings added at USAF insistence, so that it had the ‘cross-range capability’ to land at other airfields if military issues demanded it. Even so, at subsonic speeds the Shuttle flew like a brick: its steep approaches to Edwards and to Kennedy Space Center were at its natural glide angle (Fig. 20), not due to astronaut bravado, and if anyone had fallen out of it, the Shuttle would have landed before they did. On hearing of its flight characteristics, the late John Braithwaite remarked, “You’d be safer flying the box it came in”.
The X-24B flew complete simulations of the Shuttle’s approach, including its 300 feet-per-second descent and 200 mph-plus landing, and testing the effects of touchdown on the Shuttle tiles. Al Eggers said that flying simulations in the F-104 Starfighter beforehand helped, “because you know that guy’s got a good set of brakes” (A.J. Eggers, lecture, ‘NASA’s Evolution of the Lifting Body’, Smithsonian Air & Space Museum Seminar, op cit). The last pilot to fly it was Dick Scobee, who was to die just over ten years later as Commander of the Challenger on its final mission.
Among many shapes considered for the Shuttle was one by Lockheed for a 2-man military personnel transport, with extending wings to stabilise it for landing (Fig. 21). This evolved into a family including the Lockheed L-301 (informally called the X-24C), the MRS (Manned Reusable Spacecraft) and the FDL-5, intended for testing from the Shuttle. Small models of a version called Hyper-3, with four fins at the stern, were flown at Edwards Air Force base (renamed the Dryden Flight Research Center), where personnel built a half-size mockup on their own time in hopes to have it air-dropped from a helicopter, for which they failed to obtain funding (Fig. 22). Photographs of it began to circulate on the Internet in the 1990s, by way of Russian websites, and may be responsible for some of the suggestions that the USAF had a secret alternative space programme (see below).
In 1995, anticipating the end of Space Shuttle operations, NASA invited three aerospace companies to submit proposals for an unmanned cargo vehicle for deliveries to the Space Station, to complement the X-33 manned one in the RLV (Reusable Launch Vehicle) programme (not to be confused with my own RLV – see ‘My SF’, ON, 10th September 2023). The specification called for 11 tonnes’ delivery to the ISS, 18 tonnes to Low Earth Orbit, and horizontal runway landing. The one selected was the Orbital Sciences air-launched lifting body proposal, which was designated the X-34. It was cancelled at the stage of glide tests, but the USAF took it over and developed it into the X-40A, test-flown between 1998 and 2001, as a test vehicle for the X-37B (Fig. 23), which is delivered by Atlas V to long stays in orbit for purposes which the Air Force has so far declined to make public. (In Fig. 23, showing the X-34, X-40A and X-37B at Edwards Air Force Base, note the T-38 astronaut trainers at the rear.)
One of the more annoying claims, by space enthusiasts who got their information from right-wing US websites, was that the US military had an extra Space Shuttle codenamed ‘Black Horse’, launched and landed ‘in secret’. It’s only slightly sillier than the claim that the USA is still flying Saturn V in secret, to a base on the Farside of the Moon: nobody who has witnessed a Saturn launch, a Shuttle launch or even a Shuttle landing with its sonic boom, would imagine that any of them could happen without being seen or heard. Another version, even less probable, was that the fully crewed Black Horse was being air-launched into orbit from the back of an SR-71 Blackbird. A small satellite could be put up that way: the winged, unmanned Pegasus booster was initially launched by NASA’s B-52 and later by Orbital Sciences’ converted TriStar (see ‘Rockets, for November 5th’). But even to put the 20-foot X-37B into orbit unmanned takes a full-sized Atlas V launch; none of which prevented Black Horse believers from claiming, when it first flew, that they had been right all along.
The X-33 ‘Penguin’, proposed as the successor to the Space Shuttle (Fig. 24), was too ambitious, attempting too many new technologies at once. Its linear aerospike engine looked promising, but its composite fuel tanks with lithium alloys proved a step too far. Designs for even larger vehicle such as the Mixed-Mode Space Shuttle (Fig. 25), or the Rockwell Star-raker (Fig. 26), have to wait for a need to move larger numbers of people or big cargoes. The Star-Raker design had a new lease of life in the mid-1980s, when a single scramjet engine replaced its multiple turbojets (Fig. 27), but it was no coincidence that it was shown delivering guests to the Orbiter Hilton.
The Ansari X-Prize competition in the late 1990s generated multiple innovative designs; it was won in 2004 by Virgin Galactic’s Spaceship 1 (Fig. 28), with Burt Rutan’s highly original design, and Spaceship 2 is now conducting suborbital passenger flights, for research as well as tourism, but is about to be withdrawn pending development of a new ‘Delta’ variant. The other contenders have disappeared off the scene, and the loss of X-COR Aerospace is particularly to be regretted, because there was every chance that its Lynx vehicle would fly from Prestwick.
I have been an advocate of the Prestwick Spaceport since February 1956, when I was 10, and the Express Weekly published a feature showing a giant A4B carrying passengers from New York to Heathrow (Fig. 29). “Why not Prestwick,” I immediately asked, “when it’s obviously so much more suitable?” The Prestwick Spaceport is now officially part of the redevelopment plan for South Ayrshire. But early artwork for it in 2015 (Fig. 30) showed the Spaceport serving Virgin Galactic (currently preferring Cornwall, if it flies from the UK), the X-COR Lynx (cancelled in 2017), and Alan Bond’s Skylon, whose airframe won’t even be begun until its revolutionary Sabre engine is perfected. Prestwick Airport is under five miles from here in Troon, but winged, human spaceflight from there still looks to be a long way down the road.
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