Extreme Punchout: The Ejection Seat of the X-15

The hypersonic speed and extreme altitude performance of the North American X-15 demanded one of the most complex ejection seats ever put into service. Earlier NASA research rocket aircraft like the Douglas D-558-2 Skyrocket and the Bell X-2 featured ejectable nose sections that the pilot would then bail out of conventionally once it had separated from the aircraft and stabilized. However, the weight and volume restrictions on the X-15 made such a system impractical and North American in conjunction with engineer/test pilot A. Scott Crossfield, North American Aviation designer Jerry Madden and the David Clark Co. (who had long made pressure suits for the military and NASA) designed an integrated system that combined the pressure suit design along with an advanced ejection seat.

The X-15 ejection seat in the aircraft
(USAF Museum)

David Clark's MC-2 pressure suit was the key to making an open-faced ejection at high Mach and high altitudes possible. It not only protected the pilot from the extreme windblast of hitting the airstream at Mach 3+, it also functioned as a pressure suit to protect the X-15 pilot at altitudes in excess of 250,000 feet. Despite the advanced nature of the pressure suit, it was understood that kinetic heating during a high-Mach ejection would probably result in mild burns to the head, knees, and toes which in effect projected into the airstream.

Because the rocket motor of the X-15 ejection seat had to be powerful to propel the pilot clear of the X-15's hypersonic shockwave, a novel means was used to transfer loads from the pilot's rear end to the seat pan. Each X-15 program pilot sat on a weather balloon filled with plastic beads and wiggled into it like a bean bag. A vacuum was applied which held the shape of the balloon. Once the pilot stood up, plaster of Paris was poured into the depression, creating an exact copy of the pilot's rear end. A block of Balsa wood was then carved to precisely fit the mould and this became the seat cushion of the X-15's ejection seat- not only was it custom fit which allowed the optimum transfer of shock loads from the pilot's body to the seat pan, it also made for a very comfortable seat!

Scott Crossfield in the MC-2 pressure suit
(NASA/Dryden Flight Research Center)

To prevent the flailing of the arms and legs during a high-Mach ejection, special articulated restraints would protect the pilot's legs and feet (also acting as a windblast deflector to minimize heat burns on the feet) as well as to the arms and hands. The articulated arms deployed gauntlets to protect the pilot's hands from aerodynamic heating as well.

Once the articulated arms deployed into place, the emergency oxygen supply took over pressurization of the suit and a heating unit activated to keep the pilot's helmet visor clear of ice. Once the canopy was blown off and the seat traveled up the rails, special wings on the sides of the seat deployed to stabilize the seat in the high-Mach airstream. In a conventional ejection seat, a drogue chute would be deployed to slow the seat down but at the X-15's speeds, such a chute would have melted instantly, so the X-15's seat deployed a pair of telescopic booms that projected aft and outward from the bottom of the seat to provide aerodynamic braking and helped the wings stabilize the seat.

Rocket sled test of the X-15 seat- note the deployed booms
(Boeing)

If ejection took place over 15,000 feet, a built-in barostat kept the pilot attached to the seat which allowed use of the seat's emergency oxygen supply. Once 15,000 feet was reached, the seat automatically released the pilot and activated his parachute. If ejection took place below 15,000 feet, a three second timer allowed the wings and drogue booms to deploy and stabilized the seat before separating from the pilot.

One little-known fact was that the X-15 cockpit was pressurized with nitrogen instead of oxygen as was used in the Mercury and Gemini spacecraft. The pilot breathed oxygen from the his suit which was only pressurized upon ejection. This meant the cockpit was fireproof, something that NASA tragically learned with the launch pad fire on Apollo 1.

The X-15s set an absolute speed record of Mach 6.7 and an absolute altitude record of 354,000 feet which qualified several of its program pilots for astronaut wings. Fortunately the ejection system was never needed and the one fatality, Michael Adams, occurred when his X-15 lost control and broke up on re-entry into the thicker levels of the atmosphere and the X-15's complex ejection system might not have saved him.

Interestingly, the David Clark MC-2 pressure suit served as the basis for the space suits for the Mercury and Gemini programs. The aluminized fabric exterior of the MC-2 suit carried over to the space programs and heavily influenced Hollywood cinematic depictions of space suits well into the 1970s.

Related reading: 

Lockheed's Contribution to the Space Shuttle Program
The Boeing 747 SCA Shuttle Carrier Aircraft
Flight Testing on the Cheap: The Groundbreaking M2F1 Lifting Body
How the Shuttle Orbiter Lost Its Jet Engines

Source: Eject!: The Complete History of U.S. Aircraft Escape Systems by Jim Tuttle. MBI Publishing, 2002, p136-143.

Martin, the Titan I, and the Titan II Ballistic Missiles

Titan I ICBM elevated out of its silo for laugh
(USAF Museum)

When George M. Bunker took over the reins of Martin Aircraft from Glenn Martin in 1952, Bunker wanted to diversify Martin which up to that point had produced only aircraft. With an able group of lead engineers that Glenn Martin had literally hand picked in the years prior to his retirement from his company, Bunker moved some of Martin's engineering and research efforts into the rocket and missile arena that bore first fruit with the Viking research rocket and the Vanguard light satellite launcher built for the Navy. While many in the growing rocket and missile division were focusing their efforts on the Vanguard program, it was Jess Sweetser, Martin's VP for Sales and Requirements, who pushed the company to bid for the second USAF ICBM contract. At the time, General Bernard Schriever was heading the Western Development Division (WDD) in Los Angeles which directed the ICBM effort that started off with the Atlas ICBM built by Convair. Schriever wanted a second ICBM system fielded as a backup to the Atlas and the WDD issued a requirement that spelled out the range, guidance and throw weight (the payload of the missile, which was the nuclear warhead). Left up to the contractors would be the missile configuration, liquid vs. solid propellants, staging and number of engines.

Sweetser got to know General Schriever so well they became golfing buddies* in their free time and as a result, he was able to anticipate the need for a second ICBM program from his conversations with the general. As a result, when the WDD issued the requirement, Martin's team of engineers was already doing preliminary work in addition to their work on the Vanguard launcher for the Navy. It became clear from further directions from the Western Development Division as well as the operator of the ICBMs, the Strategic Air Command, that not just a backup ICBM was wanted, but one that was a true alternative to the Atlas ICBM and if possible, more advanced. With both Boeing and Lockheed in the competition for the alternative ICBM contract, George Bunker split the rocket and missiles team into two parts- one group stayed on the East Coast and worked on the Vanguard launcher, the other group set up shop in Los Angeles next to the WDD to work on their ICBM design. Martin's design was based on work that had been already done for the Vanguard launcher- instead of the thin, pressurized balloon skin arrangement used on the Atlas, the Martin proposal used two liquid propellant stages made of a rigid framework of copper-aluminum alloy with the tank wall integral to the rocket walls for weight savings as had been done on the Vanguard. The first stage would use two powerful 150,000 lb thrust engines and the second stage used a single 80,000 lb thrust engine that would be ignited in zero-gravity in near-space, a first for such a large engine. The Vanguard had proved that near-space ignition of the second stage was possible, but this would be the first large-scale application. 

In addition, Martin's ICBM design would be modular, allowing the design to be enlarged over time for heavier payloads. The sweetener of the proposal that would win the USAF contract for Martin in December 1955 was the creation of an all-new development, testing, and production facility in one location at the base of the Rocky Mountains in Littleton, Colorado. This was chosen for two reasons- first, the valleys in some of the mountains could house engine test stands with the mountains acting as natural sound insulators for the surrounding area, and secondly, Martin pointed out that a mid-continent facility was furthest away from the coasts which could be vulnerable to Soviet submarine missile launches and bomber attacks. Ground was broken on the Littleton facility outside of Denver in February 1956 for the missile that the USAF christened the Titan. As a result of the USAF's requirement that everything that went into the Titan missile be thoroughly tested, the first facilities built were the test stands, some of which replicated full size launch pads were complete Titan missiles could be tested. 

Just three years after the start of construction on the facility itself, the first Titan I missile was flight tested from Cape Canaveral on 6 February 1959. The second, third, and fourth test flight were a success, unprecedented in a new rocket or missile program. The fifth and sixth flights were failures with explosions on the launch pad, but the seventh flight was a success and by 1960 Martin had 11 more successful Titan I test flights. Out of 18 test flights, only two Titan I test flights failed, a success rate that was stunning and groundbreaking given the technology of the time. 

Titan I 3x3 ICBM base layout
(USAF Museum)

The first Titan I silos were built in 1959 in the Lowry AFB gunnery range just east of Denver. The first Titan I ICBMs went on nuclear alert on schedule in August 1962 at Lowry AFB. As the Titan I used liquid oxygen as an oxidizer, the missiles were kept the silos until the launch order was given. At this point a massive elevator lifted the Titan I out its silo to an above ground position where it was fueled for launch. All of the necessary facilities were deep underground, even the propellant storage tanks. Each ICBM squadron had nine Titan Is in groups of three. Each group of three missiles were part of a single launch complex. Once the missiles were fueled, the radio guidance domes also were elevated from their own silos. The radio guidance system tracked the missiles after launch and fed the necessary course corrections, much like the guidance system used on the Atlas ICBMs. 

With advances in Soviet ICBMs, though, while the Titan I flight test program was taking place, Martin's engineers were already working on a successor, Titan II. Titan II had an even bigger warhead and the modularity of the Titan design paid off as the engineers merely had to fatten the second stage to the same diameter as the first stage and then lengthened both stages for a bigger missile. To replace the radio guidance system on the Titan I, AC Delco and MIT created a new inertial guidance system that set the standard for ICBMs. No longer would radio signals from the launch site be necessary, minimizing the Titan II's vulnerability to a counterstrike. The liquid oxygen was also replaced as the oxidizer and Titan II now had non-cryogenic storable liquid propellants- Aerozine-50, which was a mix of hydrazine and unsymmetrical dimethylhydrazine (UDMH) and dinitrogen tetroxide as the oxidizer. As a result, no fueling process was needed. 

Titan II silo "hot launch"
(USAF Museum)

The simplification of the Titan II launch complexes compared to the Titan I was dramatic. Major underground structures dropped from 42 to just 18 structures, 6,000 feet of service tunnels were reduced to just 945 feet, the power requirements dropped from 12,000 kilowatts per squadron to just 2,700 kilowatts. Only half the wiring connections were needed and the need for periodic checkout of missile systems dropped by an astounding 90%.  As a result, the silos could be more widely dispersed. With a formal contract awarded in 1960, the Titan II flight test program went smoothly- of 33 test launches, 25 were successful- in fact, the last 13 test launches were so successful and reliable, the Titan II was selected by NASA to be the launcher for Project Gemini. 

With this reliability came the need to solve the basing issue. The Titan I was housed in silos, but it was lifted out of the silo for launch. Martin's engineers argued that it was possible to launch the Titan II right out of its silo, dramatically reducing its response time. Significant debate ensued about the feasibility let alone the safety of launching the 110-foot Titan II with its 430,000 lbs of first stage thrust right out of a silo. On 19 February 1963, a test Titan I was successfully launched from a Titan II test silo at Vandenberg AFB in California, validating the concept so clearly that the USAF had Boeing incorporate silo-launch on its Minuteman ICBM. The first Titan II missiles went on nuclear alert in 1963 just one year after the first Titan I missiles went on alert! 

The Titan I missile squadrons were operational from 1962 to 1965 at Lowry AFB in Colorado, Ellsworth AFB in South Dakota, Beale AFB in California, Larson AFB in Washington, and Mountain Home AFB in Idaho. Only Lowry AFB was home to two Titan I missile squadrons while the other bases only hosted a single squadrons. The Titan II missile squadrons were grouped three squadrons to a missile wing and were operational from 1963 to 1987 at McConnell AFB in Kansas, Little Rock AFB in Arkansas, and Davis-Monthan AFB in Arizona. The modularity of the Titan design, though, made it a versatile heavy-lift space launcher. Not only did the Titan II launch the manned Gemini missions, but it was also used as a satellite launcher until 2003. Titan III and Titan IV were exclusively space launchers, with the last Titan IV launch in 2005. In 1995, when Lockheed merged with Martin Marietta, the Colorado facility became part of the Lockheed Space and Missiles Division. Since the retirement of the Titan IV launcher, the Littleton facility is now the headquarters of United Launch Alliance, the joint venture of Lockheed Martin and Boeing for the Delta and Atlas launch vehicles. Although no production takes place there any longer, ULA still has its mission control, testing and engineering facilities at the same location that was the birthplace of the Titan missile when ground was broken over fifty years ago.

Historical tangent: 

I had mentioned above how Martin Aircraft's VP for Sales and Requirements Jess Sweetser, had become a golfing buddy of USAF General Bernard Schriever. Before he came to work for Martin Aircraft, Jess Sweetser was a championship golfer in the 1920s. While a student at Yale, Sweetser had won the National Intercollegiate Championship in 1920, placed 11th at the US Open the following year despite his youth, and won the Metropolitan Championship  in 1922 in his junior year at Yale. He then won the US Amateur Championship that same year and then became the first American to win the British Amateur Championship in 1926 despite having the flu. He played on the first Walker Cup team (a trophy for amateur golfers in the United States, Great Britain and Ireland) in 1922 and five more teams in years following. After graduation from Yale, he worked as a stockbroker and played golf on weekends. His first job in aviation was with Curtiss-Wright before he came to Martin Aircraft. 

Source: Raise Heaven and Earth: The Story of Martin Marietta People and Their Pioneering Achievements by William B. Harwood. Simon and Schuster, 1993, p299-325

How a Lot of Airbus Jets Were Born on Boeing Wings

A340 fuselage barrel being loaded into 377SGT No. 3

With the formation of Airbus Industrie and the launch of the Airbus A300 jetliner, the different consortium partners finalized their workshare of the project- the tail section was the responsibility of the Spanish, the British were responsible for the wings, the Dutch fabricated all the moving surfaces of the wing, the Germans built the forward and aft fuselage along with the top section of the center fuselage, and the French were responsible for the nose, flight deck, control systems, the lower section of the center fuselage and final assembly of the A300. Splitting up the construction of a commercial aircraft in this manner wasn't necessarily new to the aerospace industry- after all, Boeing had about 65% of the Boeing 747 farmed out to various subcontractors with over 20,000 companies in just about every one of the fifty US states and some foreign nations. But what was novel in what Airbus was doing was that it was the very heart of the enterprise with the partner nations assuming near-equal risk. This would be how every Airbus jet would be built and each partner nation would build their sections to as near complete as possible. For Boeing, they retained oversight and control over what their 747 subcontractors would be doing and providing. For the A300, each Airbus partner wasn't overseeing each other- they were more or less having to trust that each partner would provide a finished product that met the specifications and could be easily integrated into final assembly in France. This required each firm to work in near-perfect harmony and coordination with the other consortium members. There was no margin for error- it has been said that if a Swiss watch were scaled up to the same diameter as the A300's fuselage, the tolerances on the A300 were much tighter than that of the Swiss watch!

Parts were designed in such a way to facilitate this process, but other steps were necessary for proper coordination. At the Hawker Siddeley plant in the UK that built the wings, for example, they had special jigs that the wings could be "plugged" into that replicated the fuselage center section that they would join up with in the final assembly hall in Toulouse. More difficult was getting each nation to adopt the same production techniques. During the early days, engineers at Airbus joked how easy it was to tell whether a particular join in the aircraft was done by the French or Germans. But it had to work and with great perseverance, the A300 was coming to shape. 

Surprisingly, in the early days of Airbus, the biggest problem they faced in getting the A300 into production was the logistics of having factories in France, Germany, Spain, Great Britain and the Netherlands all separated by significant distances. The straight line distance from Germany's Hamburg production facility to the final assembly hall in Toulouse was 900 miles. It was originally planned that all the large sections would be transported by sea- this was why the German Airbus facilities were in Bremen and Hamburg which had easy sea access and the Hawker facility had good road links to the port at Liverpool. Toulouse, however, is about 100 miles inland with no sea access. The original plan was to transport the fuselage and wing sections up the Garonne River from Bordeaux on the Atlantic coast. Because of the depth of the river and the size of the components, they would only be able to up about 50 miles from Bordeaux at which point the components were transferred to a road convoy- to minimize disruption along the route to Toulouse, it had to be done at night and numerous telephone poles, trees and power lines would have to be relocated. Some of the transport vehicles would be near 100-feet in length and it wasn't long before Airbus officials came to their senses and realized that this was a very inefficient and time-consuming process to get airframe components to final assembly. 

Airbus Skylink, Felix Kracht's solution for Airbus' logistical problem

The A300 production manager was a German engineer named Felix Kracht. Before joining the nascent Airbus in 1968, Kracht had worked on harmonizing production methods and standards on the Franco-German C160 Transall military transport program. About the time that the A300 program had been launched, Kracht was familiar with Aero Spacelines and its founder, Jack Conroy. Aero Spacelines was established by Conroy to convert Boeing 377 Stratocruisers into outsize cargo transports for NASA. Not only did ASI design and convert the aircraft, they also operated the aircraft as well. The first conversion was done in 1962 using a retired Stratocruiser and was called the Pregnant Guppy which transported both Titan II stages for the Gemini program and Saturn stages for the Apollo program. By 1970 a bigger and more capable Guppy had made its first flight- longer and more capacious than any of Conroy's other designs, the new Super Guppy Turbine (377SGT) was turboprop-powered. The first 377SGT made its first flight after conversion on 24 August 1970 and the second 377SGT first flew on 24 August 1972. By this point, however, ASI was in financial trouble and that's where Felix Kracht and Airbus stepped into the picture. He astutely realized its capacious fuselage and swing-nose loading were the perfect solution to the logistical problem of getting large airframe sections to Toulouse for final assembly. In 1970, Kracht had arranged for Airbus to purchase the first 377SGT with delivery in 1971. The purchase deal included a contractual commitment from ASI to build a second 377SGT as a back up for Airbus to serve as a back up for the first 377SGT. With ASI in dire financial straits in 1973 as the Apollo program was winding down, Airbus purchased the second 377SGT built. Plans then evolved once A300 production had been launched for a third and fourth 377SGT to be built for Airbus. By this point ASI was in no position to complete construction of two more aircraft, but they did complete sub-assemblies which were then completed in France. The third 377SGT first flew in 1979 and the fourth and final 377SGT first flew in 1980. 

Operating the Super Guppy fleet wasn't cheap, but in terms of time savings and efficiency, the cost was worthwhile compared to any sea/ground-based transport option. As the battle with Boeing heated up in the late 1970s, Boeing criticized what was called the Airbus Skylink program but Airbus responded by overlying a map of Boeing's subcontractors over a map of the Airbus partners to show the distances flown by the Super Guppies was shorter than the distances from Boeing's subcontractors to final assembly in Seattle. By the 1980s, though, the age of the Super Guppy fleet was becoming a significant cost center for Airbus. In 1991, the French company Aerospatiale and the German company DASA formed a joint enterprise to develop and build a replacement for the venerable Super Guppy fleet, ironically based on the A300. Construction of the Airbus Beluga began in September 1992 with the first flight taking place in 1994. A total of five Belugas have been built with the last one completed in 1999 which allowed for the retirement of the Super Guppy fleet. 

377SGT No. 4, now N941NA operated by NASA

Super Guppy No. 1 was retired in 1996 and resides at the British Aviation Heritage Museum at Bruntingthorpe awaiting proper restoration. Super Guppy No. 2 was also retired in 1996 and is on display at the Airbus facility at Toulouse and is under the care of the group Ailes Anciennes Toulouse ("Toulouse Old Wings"). The Musée de l'Air et de l'Espace at Le Bourget was offered Super Guppy No. 2 initially, but they had to decline on account of space considerations. Super Guppy No. 3 was retired in 1997 and is on display at the Deutsche Airbus facility at Hamburg Finkenwerder, Germany. Super Guppy No. 4, however, continues to earn its keep, but no longer for Airbus. In an International Space Station barter agreement, Super Guppy No. 4 was transferred to NASA in exchange for delivery to the ISS by the Space Shuttle components from the European Space Agency. Now with tail number N941NA, the NASA Super Guppy transported ISS modules destined for in-orbit assembly and currently transports launch payloads. 

As an interesting note on Super Guppy No. 4/N941NA- when Aero Spacelines was building the sub-sections for Airbus, the company found that there were no more spare Boeing 377 Stratocruisers that could be cannibalized to form the lower aft fuselage. The dismantled original Pregnant Guppy that first flew in 1962 was still available and was purchased for its lower aft fuselage which was incorporated into Super Guppy No. 4/N941NA. Now here's what's interesting- the Pregnant Guppy was converted from the third Boeing Stratocruiser prototype that made its first flight in 1948! That means that not just a significant portion of Airbus jets produced made their "first flight" on the third Stratocruiser prototype (so to speak), but so did some of the modules of the ISS. 

Further reading: 

How American Airlines Shaped the A300

How Rolls Royce Scuttled British Participation in Airbus

The Early Days of Airbus Industrie and How the A300 Got Its Name

Franz Josef Strauss: The Bavarian Politician Who Saved Airbus

Related reading:

American Airlines Picks the DC-10 (American's pick of the DC-10 is intertwined with the early history of Airbus)

Sources: Close to the Sun: How Airbus Challenged America's Domination of the Skies by Stephen Aris. Agate Books, 2002, pp 56-62. "All About Guppys" at www.allaboutguppys.com. Photos: Wikipedia, Airbus.

How the Shuttle Orbiter Lost Its Jet Engines

The McDonnell Douglas design with a large flyback booster

As design work by various aerospace companies began on the Space Shuttle program in the late 1960s, it was a given that the Orbiter would have its own jet engines. Having its own air breathing engines offered three advantages- they would allow atmospheric flight testing much like any other aircraft was tested and pilots could practice landings in the run up to an orbital mission. The engines also facilitated ferry flights, repositioning the Orbiter amongst various facilities (landing, launch, overhaul, etc.). Having its own jet engine propulsion also gave the Orbiter cross range capability upon return from orbit. Some designers envisioned the Orbiter rendezvousing with a tanker for additional jet fuel. But in the ascent and in orbit, jet engines and fuel for those engines was dead weight that subtracted from potential payload. Even if designers went with an Orbiter design that was unpowered on its landing, the 1970 and 1971 design studies prominently featured a fully reusable two stage Space Shuttle with a big flyback booster that would have to have its own jet engines. Some of the designs for the flyback booster were massive with a need for as many as twelve jet engines. Soon the design of the flyback booster itself began to take on technical challenges that rivaled that of the Orbiter design itself. The weight of up to twelve jet engines and the necessary jet fuel cut into the payload of liquid hydrogen and liquid oxygen for the booster's rocket engines. Many of the flyback booster designs would need approximately 150,000 lbs of jet fuel (for comparison, a Boeing 777-200ER has a fuel capacity of roughly 300,000 lbs). Consideration was then given to using liquid hydrogen as fuel for the jet engines which would cut out the need for jet fuel tanks. In June 1970, NASA issued contracts to GE to study the feasibility of using liquid hydrogen in the F101 engine being developed for the B-1 bomber. Pratt and Whitney also got a similar contract to study the use of liquid hydrogen fuel in the F401 engine, the planned naval derivative of the USAF's F100 engine planned for the F-15 Eagle. Both companies showed that liquid hydrogen fueled jet engines saved about 2500 lbs of weight per jet engine compared to conventionally-fueled jet engines. The weight savings was modest at best. 

A typical high-key to low-key unpowered approach to landing

At the same time these studies were going on on how to save weight with Orbiter and flyback booster-mounted jet engines, with NASA there was a group at the Flight Research Center at Edwards AFB where unpowered landings were routine for many high speed research aircraft going back to the X-1 (the X-15 program being the most recent one at the time) and the graduates of the co-located Aerospace Research Pilot School had as a requirement that students demonstrate proficiency in unpowered landings using the school's Lockheed F-104 Starfighters which were throttled down to idle for the practice sessions. Even more demanding were the unpowered landings made by the lifting body program aircraft that lacked wings and derived their lift from their tubby fuselage designs. Regardless of what sort of aircraft was used, USAF test pilots and the NASA-FRC pilots used what was called "energy management" where they traded altitude for airspeed on the descent and used turns to bleed off speed in preparation for final approach. The first step in unpowered landings was the arrival at the "high key" which was high above the touchdown point. From the high key, a gradual 180 degree turn was made that allowed speed reduction and descent to the "low key" which was usually abeam the touchdown point. From the low key, the turn continued allowing more speed to bleed off and the descent to continue until lined up for final approach. If at any point the speed was excessive, speed brakes or gentle S-turns could be used to get down to the necessary airspeed. The lifting body pilots found that on final approach, diving at the runway touchdown point 15 degrees or more improved their accuracy as the speed improved the stability and the speedbrakes could be used to moderate the speed build up on final approach. An assessment by one of the experienced lifting body pilots in September 1970 showed that in 30 landings on a 10,000 foot runway from altitudes as high as 90,000 feet and speeds as high as Mach 2, the dispersion of the landing points was only 250 feet. 

However, the astronaut office in Houston at the Manned Spaceflight Center headed by Deke Slayton felt that unpowered landings for the Orbiter were too risky. Slayton was concerned that the test pilots were more proficient at unpowered landings than his astronauts would be, especially if they were returning from a 7-10 day orbital mission. The astronauts' views carried considerable weight for good reason and it took the USAF to swing the design work in favor of unpowered landings. 

I had posted previously that the Space Shuttle program's development phase was taking place during a period of budget austerity. One of the keys to navigating the budgetary climate of the day was to be sure to secure as much political support as possible since Congress determined the program budget. But in 1970 the program had some close calls, narrowly avoiding funding cuts in both the House and Senate. The Air Force offered to lend its support as it saw opportunity in the Shuttle program to launch heavy reconnaissance satellites. But NASA had baselined the Orbiter design at the time with a 25,000 lb payload to orbit. The USAF wanted to put its heavy reconnaissance satellites into polar orbit and the Orbiter needed a payload capacity of 40,000 lbs. That much payload weight into polar orbit (and unable to take advantage of the Earth's rotation for additional boost) was equal to a 65,000 lb payload launched for the Kennedy Space Center. NASA informed the USAF that the payload had to be baselined at 25,000 lbs due to the weight of the jet engines and their fuel. But it was apparent from the Congressional battles that NASA needed a strong ally like the USAF, so the jet engines were dropped from the Orbiter design and that allowed the payload capacity to orbit to meet the USAF requirements. 

The idea of onboard jet engines didn't end, though. NASA shifted towards the idea of removable kit that could be used for flight testing, ferry flights, and for return from orbit if the payload wasn't maxed out. This also coincided with the 1971-1972 time frame when the flyback booster was dropped as too much of a technical risk and the Space Shuttle began to look more like its final design- an Orbiter with an external tank and solid rocket boosters in what was called the TAOS configuration- Thrust Assisted Orbiter Shuttle. The significant weight savings by going to a TAOS configuration also helped cut development risk as there was a considerable amount of experience already with solid rocket boosters and large external tank structures to hold cryogenic fuels. 

The test pilots at NASA-FRC persisted in their opinion that jet engines were completely unnecessary in the Orbiter design. They had their long experience of over 10,000 unpowered landings since the X-1 program as their proof, but the astronauts insisted that the Orbiter was a much bigger aircraft than many of the X-planes. Another round of tests then were held by NASA-FRC, this time using their B-52 Stratofortress carrier aircraft. Set up in a high drag configuration with the engines at idle, pilots successfully and accurately landed the B-52. NASA-FRC then got some lifting body pilots who had never flown anything as big as the B-52 and had them fly the bomber through a simulated unpowered landing using energy management. They were able to land successfully and when the same pilots were asked to land the B-52 using a conventional powered low angle approach, none of them were able to do so. The test pilots the FRC even brought into two United Airlines pilots to fly the B-52 in simulated unpowered landings and they had no issue doing so, reporting that such landings were much easier than conventional landings. The test pilots then followed up the B-52 tests with the same tests using NASA's Convair 990 which could simulate the Orbiter aerodynamics on landing. 

The final iteration of a jet-engine powered Shuttle Orbiter (from the Dennis Jenkins book)

NASA finally got agreement to go to exclusively unpowered landings on return from orbit for the Shuttle Orbiter, but the jet engines still didn't go away. At the time of Rockwell's award in 1972, the Orbiter design featured two engines that deployed from the payload bay and two more engines that could be mounted on struts. Less than six months later, the Orbiter design dropped the internally mounted jet engines completely and they were to be mounted as a kit on the flat underside when needed for flight testing and ferry missions. It finally took the ferry range to kill the engines completely from the Orbiter design. The Orbiter was similar in size to a Douglas DC-9 but had twice the weight. It had a lot of drag since it wasn't optimized for atmospheric flight and the delta wing was highly loaded. With five jet engines mounted in pods on the underside and tank of jet fuel in the payload bay, the Orbiter had a ferry range of only 500 miles. With Space Shuttle sites across the nation and contingency fields overseas, a 500 mile range was simply unacceptable. NASA looked at aerial refueling during ferry, but this added complexity to a design that was already experiencing cost overruns. In February 1974, NASA deleted the jet engine requirement completely. As a result, both for flight testing and ferry flights, the Orbiter would need a carrier aircraft, but fortunately that was a lot more straightforward a development process!

The Buran analog with its four AL-31 jet engine nacelles

Interestingly in the Russian Buran Shuttle program, there was an aerodynamic test analog designed OK-GLI that made 25 atmospheric test flights with four Lyulka/Saturn AL-31 jet engines mounted in nacelles in the aft fuselage. A fuel tank sat in the payload bay. The AL-31 is the jet engine that is used on the Sukhoi Su-27 Flanker. Nine taxi tests and 25 test flights were made using the Buran analog from December 1984 to December 1989. The engines were used to takeoff and then were throttled back on the descent to landing. All of the flight testing took place at the Baikonur Cosmodrome. The operational Buran, however, would not have jet engines at all and the Antonov An-225 Myria was developed as the carrier aircraft to ferry the Buran orbiter. 

Source: Development of the Space Shuttle 1972-1981: History of the Space Shuttle, Volume Two by T.A. Heppenheimer. Smithsonian Institution Press, 2002, pp85-92. Space Shuttle: The History of the National Space Transportation System- The First 100 Missions by Dennis Jenkins. Specialty Press, 2008, pp187-192. Photos: NASA, Wikipedia, Dennis Jenkins. 

The Industry Cooperation in the Lockheed Electra Investigation.

The outboard nacelle- the Achilles heel of the Lockheed Electra

In my previous blog entry, I had discussed how subcontracting was a way of building goodwill between aerospace competitors, the example from I talked about was in reference to the Space Shuttle program. However, even aside from financial incentives, there have been times in aviation history that corporate rivals have cooperated beyond that of a joint venture and one unheralded example of such cooperation was the extensive investigation into the loss of two Lockheed L-188 Electras shortly after the type went into service. The first loss was on 29 September 1959 when Braniff International Airways Flight 542 went down near Buffalo, Texas, on a flight from Houston Hobby Airport to Dallas Love Field. The second loss was on 17 March 1960 when Northwest Airlines Flight 710 went down near Tell City, Indiana, on a flight from Chicago Midway to Miami. 

The cooperation of Lockheed's competitors began after the Braniff crash. A Dallas warehouse was used to reassemble the wreckage as part of the investigation. Using a chicken wire frame, pieces were added in a gigantic jigsaw puzzle from October into November. In January 1960, the investigators with the Civil Aeronautics Board (CAB) were no closer to determining the cause of the loss of Braniff 542 and invited representatives from Eastern Airlines and American Airlines, both operators of large Electra fleets, along with NASA to join the investigation. The following month Lockheed invited engineers from Boeing, Convair, and Douglas to review what had been done so far in the investigation. But the loss of the second Electra when Northwest 710 went down shook the airline and aviation industry as aircraft like the Electra were the leading edge of the jet turbine age that would revolutionize air travel. There was near unanimous sentiment in American aviation that the cause of the loss of two Electras in passenger service had to be found and rectified for the good of the entire industry. 

NASA immediately put its resources at Lockheed's disposal (the decision to ground versus speed restrict the Electra will be subject of a future post for this blog). Allison, the maker of the Electra's engines, initiated its own flight test program with its own company Electra. Boeing and Douglas made their resources also available to Lockheed- with both companies fielding their own advanced jetliner designs for the day, helping Lockheed determine the cause of the Electra crashes was vital to confidence in both the Boeing 707 and the Douglas DC-8. With Lockheed engineering staff getting pulled from various projects to the Electra investigation, Boeing's chief Bill Allen dispatched his own engineers and his best aerodynamicists from Seattle to assist Lockheed in Burbank. The investigation and any fix needed had a name- Lockheed Electra Achievement Program, or LEAP. To everyone involved, it became Operation LEAP. 

Part of Operation LEAP was the use of a specially instrumented Electra that was flown by Lockheed and government test pilots over the Sierra Nevada range looking for mountain wave turbulence that would shake the test aircraft as no airliner had ever before been punished in-flight. Lockheed had actually pioneering the methods for testing inflight loads on structures back in 1949 that became the industry standard in flight testing. Sixty nine flights into the rough air offered a clue- the load instruments noted that the outboard nacelles were taking a rougher beating than expected. Flutter of some sort became the suspect cause- every aircraft has some degree of flutter, the air moving over various parts and imposing loads can cause them to vibrate and if unchecked, those vibrations increase in amplitude until structures fail. Aircraft structures are designed in part to dampen these oscillations. 

With flutter as the suspect, Douglas had sent over to Lockheed a vane exciter that was basically an actuated vane mounted on the wingtip that could move quickly to induce flutter in the wings. Even in smooth air, the vane exciters could really dole out some punishment to the wing structure. Douglas had used the device in the DC-8 flight test program and put them at Lockheed's disposal. The devices in combination with the rough air flight testing showed the outboard engine nacelles were the source of the flutter and a review of the wreckage from the Braniff and Northwest crashes showed that the outboard nacelle structure in combination with the wing structure allowed an obscure type of flutter called "whirl mode"- in short, gyroscopic movements of the propeller caused oscillations in the nacelle which were then transferred to the wing which caused the wing to fail. 

Though commercial rivals, Boeing and Douglas were only keenly aware that Lockheed was well respected in the business and its engineering and design methods were top notch. Much of how Lockheed went about the design and testing of the Electra wasn't all that dissimilar to how Boeing and Douglas went about the design and testing of their jetliners. If there was something Lockheed had missed, then it was something that left their designs  and the processes used open to question as well. 

On 12 May 1960, Lockheed chairman Robert Gross announced the cause of the loss of Braniff 542 and Northwest 710 as unstable whirl mode. Think about the technology of that day as this was well before computer modeling was available. Now think about the time frame- Braniff 542 went down at the end of September 1959. Northwest 710 went down in the middle of March 1960. And by the middle of May 1960 the cause had been identified. It's one of the great herculean efforts of American aviation that an obscure flutter mode was found to be the cause in just seven months. That amazing time frame wouldn't have been possible if Lockheed didn't have the cooperation of its commercial rivals as well as NASA, Allison, and the airline operators of the Electra. 

Source: The Electra Story: Aviation's Greatest Mystery (Bantam Air & Space Series No. 9) by Robert Serling. Bantam Publishing, 1962, 1991. Illustration: Flight Simulator X screenshot.

Rockwell Builds the Shuttle by Farming Out the Work

The Grumman Shuttle Orbiter design

On 26 July 1972, NASA announced that Rockwell International had been selected as the prime contractor for the Space Shuttle (specifically the Shuttle Orbiter) after an intense competition with Lockheed, Grumman, and McDonnell Douglas. Each contractor proposal also had to detail management of the complex program as well as its technical aspects and the lengthy proposals then went to a specially convened selection board at NASA which evaluated each submission. The top two proposals belonged to Rockwell and Grumman and showcased the effect that a good management proposal could have in winning the competition. From a technical standpoint, NASA scored the Grumman proposal the best, with Rockwell's orbiter design coming in second. Rockwell's submission, however, impressed the NASA selection board with its management system. With the cost overruns on several military programs like the Lockheed C-5 Galaxy on everyone's mind, Rockwell's management proposal stressed cost controls for what was to be the biggest aviation contract in years. With a technical design not much more inferior that the Grumman design, Rockwell was awarded the contract. 

In the industry slump as Vietnam was winding down, the Orbiter contract was a very big prize for any firm that could clinch the award. At the time of the selection, Rockwell had 6,200 employees in their Space Division and with the award, plans were in place to hire as many as 16,000 by 1975. Priority would given to anyone who had worked on the Apollo program. Despite the buoyant mood at Rockwell, things were considerably more glum at the losing contenders, Grumman, Lockheed, and McDonnell Douglas. Grumman had been a mainstay of the US space program from its early days, best known for its work on the Apollo Lunar Module. Company officials made plans for Grumman to be out of the space business by December 1972 along with the attendant layoffs. 

McDonnell Douglas (via McDonnell) had built the Mercury and Gemini spacecraft and was in the midst of winding down its work as the prime contractor for Skylab. The company was also suffering from a downturn in the world commercial aviation market that was affecting most greatly its Douglas DC-9 program. 11,000 layoffs were planned at McDonnell Douglas by 1973.

While Lockheed didn't have as prominent a role in the US manned spaceflight program in the 1960s as McDonnell Douglas or Grumman, their expertise in high speed flight as well as thermal protection systems was unparalleled in the industry at the time. 

Rockwell, however, recognized two realities that came with winning the Shuttle Orbiter contract. The first one was the limitations of its in-house expertise. Quite simply, Rockwell would need other aerospace companies for their skills and expertise to bring the Orbiter to fruition. The second reality was a bit more prosaic but nonetheless vital. Keep in mind that in the early 1970s there was an atmosphere of budget austerity and NASA was no less exempt from financial realities than any other government agency at the time. Subcontracting work on the Orbiter to other companies in effect would spread the footprint of the endeavor across the districts of multiple Congressional representatives who would be routinely voting on NASA's budgetary allocations for the Space Shuttle program. Subcontracts were a common way as well in the industry of building goodwill- by farming out work to competitors and keeping them active and in business, today's winner might one day become tomorrow's loser on a another program and could hope for subcontract work from a rival. 

Rockwell planned to subcontract at least 53% of the work on the Shuttle Orbiter and this had NASA's blessing as a means of preserving the American industrial base for spaceflight. Just weeks after winning the contract as the prime, Rockwell was already conducting seminars across the nation for potential subcontractors. By March 1973 Rockwell began selecting subcontractors for the program with NASA's approval. Grumman would work on the delta wing, McDonnell Douglas got the OMS (Orbital Maneuvering System), Fairchild Republic got the vertical fin, and the Convair Division of General Dynamics got the mid-fuselage/payload bay. Rockwell would be responsible for the nose and crew compartment as well as the aft fuselage that would house the three Rocketdyne SSME (Space Shuttle Main Engine) packages. Lockheed would get the External Tank while Thiokol got the contract for the SRB (Solid Rocket Booster). 

By the summer of 1975, 34,000 workers across 47 states and a broad host of companies across the American aerospace industry were working on the Space Shuttle program. The peak would be in 1977 with 47,000 workers. The post-Vietnam slump, the Space Shuttle program was very much the crown jewel of the US aviation industry. 

Source: Development of the Space Shuttle 1972-1981: History of the Space Shuttle, Volume Two by T.A. Heppenheimer. Smithsonian Institution Press, 2002. Illustration: Aerospace Projects Review

The 747 Shuttle Carrier Aircraft (SCA)

The Boeing 747 was one of two choices for the SCA

During the design and development of the Shuttle Orbiter, air breathing jet engines were a part of the design for some time until cost and technical considerations in early 1974 led to their deletion from the concept. No longer able to "self-ferry", NASA now faced the problem of how to get the Orbiter from the remote landing sites to the launch locations. At the time NASA Langley had a study ongoing on a large aircraft design called VIRTUS that would have carried the Orbiter under the center wing flanked by twin fuselages and a twin boom tail with power coming from four Pratt & Whitney JT9D turbofans. Design work had proceeded on VIRTUS as far as wind tunnel tests with a 1/34 scale model, but sheer size, long development time and costs involved for an aircraft that would be built in very small numbers resulted in end of the VIRTUS project. At the time, Jack Conroy, the developer of the Super Guppy concept that NASA was using to transport rocket stages, had suggested using a jumbo-class aircraft to carry the Orbiter on its back. Proposals were issued to the industry and Lockheed offered up a twin-fuselage aircraft based on the C-5 Galaxy with the Orbiter suspended underneath a new center wing section- but, like the earlier VIRTUS program, it was eliminated from consideration due to cost, development time and that the design was so wide, no runway available could accommodate the design. Boeing offered a modified version of the 747 that carried the Orbiter on its back that presented a much lower risk approach. Boeing at the time even suggested that the large external tanks could be carried on the back of a 747, but wind tunnel studies showed the idea to be less practical than initially thought. Lockheed had subsequently reworked its design to a simple modification of a C-5 Galaxy to carry the Orbiter on its back much like Boeing's proposal. 

By mid-1974 Boeing's 747-based proposal and Lockheed's simpler C-5 Galaxy-based proposal were the only serious contenders to become the new Shuttle Carrier Aircraft (SCA). On 24 April 1974 NASA selected the C-5 Galaxy proposal from Lockheed based on it having the least acquisition expense and a C-5 Galaxy would need less structural modification than a Boeing 747. Accordingly, NASA approached the United States Air Force with the proposal and a request to make three to five C-5s available. The USAF was very receptive to the idea and the Lockheed proposal only added 400 to 600 pounds of modifications to the Galaxy without adversely affecting its cargo carrying capacity when not being used to transport the Orbiter. An arrangement was set up whereby NASA would pay for the modifications and then lease the modified C-5s as needed from the Military Airlift Command. One Galaxy was agreed to be bailed to NASA full-time for development into the SCA and for use in the atmospheric flight tests with the planned first Orbiter (which would become the Shuttle Enterprise). Despite some lingering concerns about the effects of the Orbiter's wake on the C-5's T-tail, both NASA and the USAF had worked out an acceptable arrangement for both parties.

N905NA conducted the atmospheric landing tests with Enterprise

The downturn in the American economy in the early 1970s led numerous US airlines to release their 747 aircraft which were too large for the market at the time. As a result, the acquisition cost of the Boeing 747 as the SCA dropped much lower than that of the Lockheed proposal. With the ready availability of low-time 747s on the market, NASA abandoned plans for using the Galaxy as it was decided it was much easier in the end to have complete control of the SCA than to have to compromise with military priorities for use of the C-5 Galaxy. On 18 July 1974 NASA purchased a used Boeing 747-123 (N9668, msn 20107) from American Airlines. It was the 86th 747 off the production line at Everett and was delivered to American on 29 October 1970. By the time of the NASA purchase, it had only logged 8,999 flight hours and 2,985 cycles flying primarily transcontinental services between New York JFK and LAX. NASA re-registered the aircraft as N905NA. Before modification into the SCA configuration, N905NA was used for in-house studies with NASA Ames on wake vortices. Following conclusion of the wake vortex research program, Boeing initiated the $30 million conversion program on N905NA on 2 August 1976. 

Not often seen is the sense of humor NASA has with the SCA

Boeing installed new bulkheads to strengthen the fuselage with skin reinforcement at critical stress areas. The horizontal stabilizer structure was also beefed up along with the addition of telemetry and transponder test equipment, fittings for the Orbiter support struts, and the installation of a 747-200 rudder actuator system. Boeing also developed a set of removable modifications for the SCA- the first one was a telescopic forward support assembly that was used only during the atmospheric flight tests with the Shuttle Enterprise. This support would hold the Enterprise at a six-degree angle of attack to facilitate release during the flight tests. A fixed assembly was also developed for use during SCA ferry missions that held the Orbiter at a three-degree angle of attack, which induced less drag during the ferry flights. The aft support assemblies (there were two) were common to both the atmospheric flight tests and ferry flights and finally 10 foot by 20 foot vertical endplates were added to the end of the horizontal stabilizer to provide additional stability when carrying the Orbiter- in practice, though, NASA never removed the endplates. 

The 747's trim system was also modified to allow a greater range of trim in pitch to counteract the downwash off the Orbiter's wing on to the horizontal stabilizer. Most of the main deck interior was stripped out, but some seats were retained for support personnel during the ferry flights. The JT9D engines were also converted to allow a thrust increase from 43,500 pounds to 46,950 pounds of thrust. The current JT9D engines on the current incarnation of the 747 SCA are rated at 50,000 pounds of thrust. Since each Orbiter has a different empty weight, an adjustable ballast system using standard cargo containers in the forward underfuselage cargo compartment had to be developed to maintain the center of gravity. On 14 January 1977 Boeing finished the modification work and after a period of flight testing, it was delivered to NASA. 

Concerns about flight crew safety during the atmospheric flight tests with the Shuttle Enterprise led NASA to incorporate an escape system on N905NA since the flight crew of the Enterprise had ejection seats. The escape system was based on what was used on the 747 prototype during Boeing's 1969 flight tests- in the event of an emergency, a handle was pulled that blew out thirty fuselage windows to facilitate rapid decompression of the aircraft. Three seconds later an emergency egress hatch on the lower forward fuselage was blown out with extendable spoiler being deployed. The crew would make their way back from the flight deck to the middle of the upper deck lounge area where a hole leading to a 16 foot escape slide would lead them out the blown hatch and clear of the aircraft. Testing showed the flight crew could bail out of the 747 within 11 seconds. The atmospheric flight tests will be the subject of a future blog post, so stay tuned. 

N905NA has three upper deck windows, N911NA has five

In 1988 NASA acquired a second 747 to act as a back up to N905NA. Part of this was driven by the recommendations following the Challenger accident that a significant portion of Shuttle flights would still be landing at Edwards AFB. The first 747-100SR was purchased from Japan Air Lines where it had flown as JA8117, msn 20781. Boeing purchased the aircraft from JAL on behalf of NASA and conducted the necessary modification work to bring it up to SCA standards with the new tail number N911NA. On 20 November 1990 it was delivered to NASA and in 1995-1996 both of the 747 SCAs were repainted in NASA's new colors. 

During a ferry mission the SCA' smaximum speed it 250 KIAS (Mach 0.6) at an altitude of 13,000-15,000 feet with a range of approximately 1,150 miles. Without the Orbiter, the SCA cruises at 24,000-26,000 feet with a range of 6,300 miles. During ferry flights the usual crew is two pilots and two flight engineers, but only one flight engineer is needed on non-ferry flights. At one point NASA looked at inflight refueling of the SCA as the equipment was readily available as it was installed on a handful of the USAF's 747s- the E-4 airborne command posts and the two VC-25A presidential transport aircraft. Proximity flight tests were even carried out with N905NA and a KC-135 tanker minus the Orbiter, but the discovery of cracks at the base of N905NA led to the termination of the studies as it was feared that wake turbulence from the tanker may have been possible. Plans were in motion to fly the proximity tests with an Orbiter, but the costs involved and wake turbulence concerns led to the quiet abandonment of the idea. 

Source: Space Shuttle: The History of the National Space Transportation System- The First 100 Missions by Dennis R. Jenkins. Specialty Press, 2001, p195-202.

Flight Testing on the Cheap: The Ground-Breaking M2F1 Lifting Body

In the early 1960s NASA's research work into lifting body designs was in full swing with the X-23/PRIME program testing lifting bodies in the re-entry regime from orbit. I had previously blogged about the PRIME program and the data that it provided the aerospace industry. But while the unmanned X-23 program answered the question of a lifting body's flight characteristics at the high speeds encountered during re-entry, questions still remained about the suitability of a lifting body in subsonic flight- would a lifting body design be controllable and stable in the low speed flight regime upon return to Earth of a reusable space vehicle? At the time, Dale Reed, an engineer at NASA's Flight Research Center (FRC) at Edwards AFB, had been following the lifting body research in his free time. Being an avid remote-control aircraft model builder, Reed built a 24-inch flying model of what was designated the M2 shape- the M1 shape was the product of research at NASA Ames which started out as a 13-degree half cone with a rounded nose. The M1 shape was refined into the M2 shape which added twin vertical fins, a canopy for a pilot, and horizontal control surfaces. This M2 shape was what Dale Reed modeled in his free time and dropped it from a 60-inch remote control "mothership" while his wife Donna would film the M2 model flight with an 8mm camera. He later showed the films to the director of the FRC, Paul Bikle, and Alfred Eggers, one of the pioneering researchers on lifting body work. They were suitably impressed with Reed's work that in November 1962 Bikle authorized a six-month program paid out of the FRC's discretionary fund to build a manned glider version of Reed's M2 model. 

The M2 glider had a steel tubular frame to which was attached the pilot's seat and landing gear (taken from a Cessna 150)- the exterior would be a light wooden shell this way different shapes could be tested. As it was, work on the lifting bodies within NASA would eventually settle on the M2 shape as the most ideal and the glider was designated the M2-F1. Space was set aside in the main hangar at the FRC which was cordoned off and nicknamed "Wright's Bicycle Shop". A local glider builder was contracted to help construct the outer shell while NASA engineers and technicians, many of whom were members of the Experimental Aircraft Association (EAA), lent their time and talents to the construction of the M2-F1. As many of them did it in the free time, it ended up costing NASA only $30,000 to build the M2-F1 when it was finished in early 1963! One of the reasons Paul Bikle funded the program out of FRC's discretionary fund was that he feared NASA headquarters in Washington would disapprove, or worse, take control of the project and make it excessively complex and expensive. 

The finished M2-F1 was 20 feet long, 10 feet high, and 14 feet wide. At the aft ends of the blunt half cone it had twin fins that mounted horizontal control surfaces nicknamed "elephant ears". The main body itself had two flaps at the end that were for trimming the glider in flight. Complete with the pilot, the M2-F1 weighed only 1,138 pounds. Later in the flight test program a Weber zero-zero ejection seat was fitted, but for the first set of flights, no ejection seat was used. By March 1963 the full scale wind tunnel tests at NASA Ames were completed with encouraging results and back at Edwards AFB tow runs were made with various vehicles pulling the M2-F1, the first captive flight taking place 5 April 1963. For these initial flights, the M2-F1 was suspended below a Rogallo wing as the vehicles weren't fast enough to pull the M2-F1 to its rotation speed. 

The engineers wanted to a faster vehicle to get the M2-F1 airborne before pulling it aloft behind a tow aircraft to higher altitudes. A 1963 Pontiac Catalina convertible was procured and stripped down. It had a 455-cubic inch engine, four barrel carburetor, and was a five speed stick shift. The engineers enlisted the help of famed California hot-rodder Bill Straup in Long Beach to replace the street tires with racing tires and to tune and tweak the engine for maximum performance. Rollbars and radio equipment were installed and the right hand front passenger seat was turned around to face aft. Adorned with the suitable high visibility markings and NASA logos, the FRC's hot rod pulled the M2-F1 for the first time airborne in June 1963. Satisfied with the near-ground/low altitude peformance, a Douglas R4D (Navy version of the DC-3/C-47) pulled the M2-F1 glider aloft for the world's first piloted lifting body free flight on 16 August 1963 when NASA test pilot Milt Thompson cast off from the tow plane at 10,000 feet and landed smoothly onto Rogers Dry Lake below. Six other test pilots flew the M2-F1 glider after casting off from the R4D towplane- Bill Dana, Capt. Jerauld Gentry, Don Mallick, Bruce Peterson, Donald Sorlie, and Col. Chuck Yeager. Bruce Peterson and Milt Thompson flew the majority of the M2-F1 flights. The M2-F1 eventually got a proper ejection seat and a small rocket was added which was fired before landing to assist with the pre-landing flare. Eventually modifications and test equipment required the M2-F1 to trade in its Cessna 150 landing gear for the gear of a Cessna 180. 

The last M2-F1 flight took place on 16 August 1966 after just over 100 flights and 400 ground tows. It was donated to the Smithsonian Institution and was restored years later and returned to NASA Dryden (what the FRC is today known as) for display. Proving that a lifting body shape could be safely flown at subsonic speeds, NASA proceeded to develop the M2-F2, a heavier, alumimum, rocket powered version that was dropped from the NB-52A and was capable of supersonic flight. Plans were to build two M2-F2s, but eventually one M2-F2 was built to supersede the M2-F1 and a competing lifting body design was built by Northrop as the HL-10. As an interesting bit of television trivia, the crash depicted in the opening of the "Six Million Dollar Man" is Bruce Peterson crashing in the M2-F2 on 10 May 1967, which he did survive. 

Source: Space Shuttle: The History of the National Space Transportation System- The First 100 Missions by Dennis R. Jenkins. Specialty Press, 2008, p36-38.

The Chrysler SERV: Thinking Out of the Box for Space Travel

Chrysler SERV ascends on its aerospike engine

By the late 1960s, the groundwork was being laid down that would eventually evolve in the Shuttle Transportation System that today is in the twilight of its career. The NASA-led studies that involved the major aerospace contractors of the day was divided into "phases" and at each phase candidate contractors had to demonstrate their concepts to the Manned Spacecraft Center (MSC) at the Johnson Space Center outside of Houston. Apollo was run out of the NASA headquarters in Washington, but the technical reach of a reusable spacecraft meant that NASA wanted the program leadership to be at a field center run by engineers- and at the time, only Houston and the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, had the technical expertise for such an undertaking. Not wanting to put its eggs in one basket, though, NASA established on 6 July 1970 the Alternate Space Shuttle Concepts (ASCC) study to evaluate alternative concepts and proposals to what was already under development in cooperation with the aerospace industry and the MSC in Houston. Given that the MSC had it hands full, program leadership of the ASCC was assigned to the MSFC in Huntsville. Over 29 configurations were studied and millions in funding were provided. A joint submission by Grumman/Boeing was evaluated, along with one from Lockheed and one from Chrysler, which at the time had a thriving space division that had been in business since 1962 building the first stages for the Saturn I rocket and Saturn IB rocket. Chrysler's ASSC proposal was the recipient of a $1.9 million study contract for what has to be one of the most unorthodox if not outright unique space shuttle concepts ever taken seriously by NASA. 

Schematic diagram of the Chrysler SERV

Chrysler's design was called the SERV- Single-stage Earth-orbital Reusable Vehicle- and it looked like nothing else under study at the time. It was a large conical vehicle that looked like a supersized Apollo command module. It was 65 feet high and 90 feet in diameter with a central payload bay 23 feet wide and 60 feet long. Liquid hydrogen and liquid oxygen tanks then surrounded the payload bay to fill the rest of the volume of the SERV. Its propulsion engine was highly innovative and developed with assistance from Rocketdyne- the SERV had a 12-module liquid oxygen/liquid hydrogen aerospike engine integral to the base of the SERV that was 87.4 feet in diameter and just over 8 feet long. The engine developed an astounding 5.4 million pounds of thrust (by comparison, each Space Shuttle Main Engine develops about 400,000 lbs of thrust at launch). Each of the 12 modules were interconnected and each had a set of turbine driven fuel pumps that could run as high as 120% to compensate for the failure of any pair of pumps in the 12 modules. The engines designed were so powerful, that the SERV's aerospike had to be throttled back to 20% just before reaching "max-Q"- the point of highest aerodynamic stress to prevent overstressing the SERV during its ascent to orbit. A series of doors could close over the aerospike modules to protect them during re-entry. 

SERV with the MURP spaceplane. Note the doors for the jet engines.

At launch, the SERV weighed in at approximately 4.5 million lbs and different modules could be attached to the top of the SERV- the most studied were an external extension to the payload bay and the other was what was called the MURP- Manned Upper Reusable Payload, which was a small orbiter design with flick-out wings on return to Earth. The MURP could carry up to ten astronauts. Launches would have taken place from large concrete pads as the SERV had its own landing legs to support its weight. To return to the Earth, the SERV would re-enter the same way as the Apollo command module did, with the blunt end first and protected by thermal tiles. But instead of a water landing, at an altitude of 25,000 feet, a set of intakes and exhaust ports opened and four banks of seven jet engines (that's right, twenty eight engines!) powered by JP-4 fuel would start up and provide deceleration and maneuver capability that would bring the SERV back home for a soft landing on its own landing legs. The planned landing site for the SERV would have been on the skid strip at Cape Canaveral adjacent to the Kennedy Space Center. 

Chrysler's space division would have built the SERV at the Michoud facility that today has been responsible for the Space Shuttle's external tank. A specially-modified transport ship would then take the completed SERV to the Kennedy Space Center. Chrysler estimated that each SERV would cost $350 million each. However, by the time the ASCC studies were winding down, the Chrysler SERV got little attention as the design submissions from Lockheed and Grumman/Boeing were decidedly much more "conventional" than the SERV- but the SERV is a fascinating exercise in aerospace development when preconceived notions are cast aside and an innovative solution is found to meet an exacting set of requirements! 

Source: Space Shuttle: The History of the National Space Transportation System- The First 100 Missions by Dennis R. Jenkins. Specialty Press, 2001, p123-125.