What Happened to the American SST?


The golden age of American aerospace prowess had to be the decade of the 1960s.  So many advances were being made across so many fields of aviation endeavor.  The Space Race demonstrated how the United States could safely and reliably place both manned and unmanned spacecraft into low earth orbit, to the Moon, and even to the planets.  In earth’s atmosphere, superb military aircraft such as the McDonnell F-4 Phantom II series and Lockheed’s incomparable A-12/SR-71 dominated the technological race in the air.  Commercial aircraft like Boeing’s  Model 707 series and its Douglas competitor, the DC-8, ruled the air miles between major cities around the globe.  However, the decade also became known for more than its share of aerospace failures, and among those failures lies the story of the American Supersonic Transport or SST.

The President’s Advisory Committee on Supersonic Transport

Only part of this story can be told by the records the NDC will be releasing shortly.  There are five boxes from the Robert McNamara Collection at the National Archives in College Park containing documents from 1964 to 1965 that date from Secretary of Defense McNamara’s participation on the President’s Advisory Committee on the Supersonic Transport. Established by Executive Order 11149 of April 1, 1964,  the Committee’s charter appeared in Section 2 of the Order:

“The Committee shall study, and shall advise and make recommendations to the President with regard to, all aspects of the supersonic transport program.  The Committee shall devote particular attention to the financial aspects of the program and shall maintain close coordination with the Director of the Bureau of the Budget in this regard.”

As represented by much of the discussion documented in this record series, President Johnson’s concern about “the financial aspects of the program” soon became the overriding concern.

SST Origins

Although the story the MacNamara Papers tell unfolds only in 1964, the American SST program had a longer history.  The aircraft industry had been examining supersonic passenger transport designs since the 1950s.  With the onset of the new administration of President John F. Kennedy, the young President tasked the Federal Aviation Administration (FAA) in looking into the future of civil aviation.  As the traveling world moved at a high subsonic speed with Boeing 707s, DC-8s, and Convair 880s, it would take a considerable technological achievement to surpass the day’s commercial airliner successes.  Upping an airliner’s speed to supersonic velocities fit the bill; however, there were those within the aerospace and airlines communities who recognized the significant risks in developing and operating a supersonic airliner.

The FAA played an unusual role in the American SST saga.  Normally a regulatory agency, the FAA actually issued a contract to investigate the possibility of a supersonic airliner.  The motivation to move quickly on this ambitious project was simple–Great Britain and France announced a partnership to build their own SST in November 1962. By May 1963, Pan American Airlines, still under the leadership of the indefatigable Juan Trippe, had confirmed an option to buy the Franco-British plane, now known as the Concorde.  Pan Am, the United States’ premier overseas airline,  had been the launch customer for the Boeing 707 in 1955 and would again be the launch customer for the Boeing 747 in 1966.  Trippe’s action on the Concorde sent a clear signal to the American aerospace industry that it needed to compete in the arena of supersonic commercial air travel.

As a result, the FAA issued a request for proposals to the aviation industry in mid-1963, not long after President Kennedy announced the establishment of a National Supersonic Transport Program during his Graduation Day speech at the U.S. Air Force Academy on June 5th.  Three aerospace giants responded: Seattle-based Boeing, Burbank-based Lockheed, and Los Angeles-based North American.  Three jet engine contractors responded as well to the search for high performance engines to power the new transport: General Electric, Pratt and Whitney, and Curtiss-Wright.  The proposals appeared in Washington DC in January 1964, and evaluation began immediately.  The irony is that the FAA’s evaluation of SST proposals began before President Johnson’s appointed Advisory Committee had its first meeting.

The FAA quickly eliminated one airframe and one engine contractor–North American’s proposal based on its futuristic XB-70 Valkyrie bomber failed along with Curtiss-Wright’s engine proposal.  The two remaining competitors for airframe and engines began their work in earnest.  The engine manufacturers both relied on previous work but chose different jet propulsion concepts for their entries.  General Electric relied on its experience in producing the J93 turbojet engine for the XB-70 program.  The J93 had a good pedigree, being an enlarged version of GE’s highly successful J79 series of engines.  Pratt and Whitney initially proposed to use a turbojet engine based off its J58 powerplant that pushed Lockheed’s secretive A-12 and SR-71 to Mach 3+ speeds.  However, P&W later changed its proposal to an immature turbofan engine design in the hopes of keeping the SST’s fuel consumption figures down to achieve the desired range and payload.

The airframes were very different as well.  The Lockheed design combined a long, thin tubular fuselage coupled with a tailless compound delta win.  The four engines were underslung in individual nacelles.  The ultimate effect was to produce a design very much like its European competitor.  The Seattle-based Boeing design had been refined over a number of years.  Boeing fell for an aerodynamic gimmick that promised its design good performance through all phases of the airliner’s flight.  For an aircraft that had to approach Mach 3 in performance, the long, thin fuselage was de rigour.  Attached to that fuselage, though, was a variable sweep wing, an expensive characteristic of many high performance aircraft designs of the 1960s.  A variable sweep wing promised optimal aircraft performance throughout its entire flight profile.  However, outside of the very experimental Bell X-5 and the Grumman XF10F-1 Jaguar, both of which were hardly success stories, variable sweep wings had not proven themselves to be practical technology on a production aircraft.  The Air Force’s newest fighter bomber, the General Dynamics F-111A, also incorporated variable-sweep wings, but its first flight took place only in December 1964.

Boeing’s Model 733-197 SST in landing configuration

What the Records Have to Say

Which brings us to the story of our records, the documents from the President’s Advisory Committee on Supersonic Transport.  The Committee had some notable members: Robert S. McNamara, Secretary of Defense; James E. Webb, NASA Administrator; Luther H. Hodges, Secretary of Commerce; Najeeb E. Halaby, FAA Administrator; John A. McCone, Director, CIA; Stanley DeJ. Osborne, Chairman of the Board for Olin Mathieson Chemical Company; and Eugene R. Black, Director, Chase Manhattan Bank.  The Executive Secretary of the Committee was Joseph A. Califano, Jr., Special Assistant to the Secretary of Defense and a Deputy Secretary of Defense.  McNamara, Webb, and Halaby had already worked together on a joint DoD-NASA-FAA study on supersonic travel initiated in 1961, so the arguments seen in the minutes do not cover much new ground.  The members of the Advisory Committee met on a regular basis to determine whether an American SST program was worthwhile.  Of all the participants, Najeeb Halaby, the enthusiastic head of the Federal Aviation Administration (and later president of Pan Am), was the main proponent of the SST program.  In reading the minutes of their meetings, one gets the impression that the President appointed all the other Committee members to keep a tight reign on Halaby.  The first question before the Committee: to which airframe/engine manufacturers should an SST development contract be awarded?

From the first meeting of the Committee on April 13, 1964, economics dominated the discussion about the SST program.  An aircraft that had to carry 30,000-pound payload for 4,000 miles at Mach 2.2 or higher would be an expensive design to build and operate.  That idea brought out the skeptics in the Committee, Chairman McNamara being the strongest.  A  McNamara quote from the first Committee meeting provides and example of the chairman’s concerns:

“But I do know that the figures that have been presented to date show the unprofitability of the supersonic to be so great that I have no confidence that following down this course of design development will ever lead to a profitable airplane.”

To which  Halaby optimistically replies: “…our (FAA) analysis of that , plus what we think to be an — a realistic evolution of that (Boeing) proposal suggests that it could, in realistic progression, probably earning 8 or 9 percent on their investment.”

A second problematic issue dealt with the sonic boom associated with supersonic aircraft.  Economy of scale came into play for keeping the costs of an SST down, and with the potential for many supersonic aircraft plying the skies over the continental United States, the impact of many sonic booms over metropolitan areas could be both dangerous and expensive.  A 1961/62 study dealing with the sonic booms associated with the U.S. Air Force’s supersonic B-58A Hustler strategic bomber flying over St. Louis, Missouri, found that the city’s population was not terribly happy with regularly occurring sonic booms, although “…overpressures of 2.6 psi were not sufficient magnitude to cause damage to sound plaster and good quality glass to break.”

Inboard profile of Boeing’s Model 733-197


After four meetings, the Advisory Committee came to four conclusions:

  1. The project is one of high technical risk.
  2. Financing the development, production and operation of the supersonic transport will require huge sums of money, will involve unusually heavy commercial risks, and will necessitate major participation by the government.
  3. Despite the high technical risks involved in this program, supersonic transport must show a potential over their lifetime to operate at costs and fares which equal or closely approximate those of future subsonic aircraft.
  4. The proposals submitted to the FAA failed to meet the established economic and technical standards.
  5. It is essential at this time to optimize the characteristics of the supersonic transport that affect commercial profitability.

With these very unsure conclusions came four recommendations:

  1. The Federal Aviation Agency should be authorized to place contracts with two airframe companies to examine the effect on aircraft purchase price, direct operating costs, and sonic boom of variations in the aircraft’s speed, size and range.
  2. The Federal Aviation Agency should be authorized to place contracts for component development and performance demonstration with the two engine companies preferred by the airframe manufacturers.
  3. The Department of Commerce should be authorized to conduct systematic economic studies to relate different types and sizes of aircraft, including advanced subsonic transports, to actual route  structures, future possible fare structures, and the varies consitions that airlines encounter.
  4. The sonic boom study should be expanded under the guidance of the National Academy of Sciences.

When the FAA awarded the airframe and engine manufacturers the recommended contract on January 1, 1965, it also mandated that Lockheed and Boeing evaluate a NASA design called SCAT(Supersonic Commercial Air Transport) 15F in an effort to address range/payload and sonic boom concerns.  SCAT 15F was a considerable departure from both previous Boeing and Lockheed designs, being both larger and more aerodynamic than the earlier efforts.

The SCAT 15F model in a NASA Langley Research Center wind tunnel (image not in McNamara record series)


By the time of the Second Interim Report of the Advisory Committee, May 8, 1965, significant progress had been made on all four of the Committee 1964 recommendations.  The recommendations in the Second Interim Report were not all that surprising–extend the contracts another 18 months for the all of the involved manufacturers (Lockheed and Boeing for the airframes and General Electric and Pratt and Whitney for the engines).  The Commerce Department economic studies determined that the SST program was still a very risky program, and sonic boom continued to be a significant problem that had the potential to limit SST air routes to overwater ones only, which would have a tremendous impact on airline profitability.  In essence, the contracts extensions to the four manufacturers were made so that they could address the technical and economic problems through engineering and manufacturing improvements to the airframe and engines.

While the McNamara records contain documents dated later than the Second Interim Report, they act more as background information as do most of the documents in the record series.  Actual records from the Advisory Committee itself appear to be limited to the first two boxes in the five box series.   The final Advisory Committee document appears to be the Second Interim Report.

SST Legacy

The story of the American SST continues on for another desultory six years after the Second Interim Report.  A down-select of the new airliner was made in December 1966 with the declared winner being Boeing’s Model 2707-390, a variation of the earlier Model 733-197.  Continuing design problems led Boeing to give up its precious variable-sweep wing as well as to shrink the design to accommodate 240 passengers, down in size from its 300 foot-long predecessor that could seat more than 270 passengers.

During the inordinate amount of time needed to design the American SST, feelings toward the new American technological triumph cooled.  Having landed a man on the moon in July 1969, the push for expensive American aerospace accomplishments lessened.  And sonic booms, which in the mid-1960s were of moderate concern, became the focus of loud and frequent ecological protests by the early 1970s.  Although the administration of Republican President Richard M. Nixon was committed to seeing an American supersonic transport fly in the decade of the Seventies, the Democrat-controlled 92nd Congress of the United States did not share the administration’s enthusiasm.  By May 1971, both Houses of Congress cancelled funding for the SST program, thus ending the saga that began with John F. Kennedy’s speech at the U.S. Air Force Academy in 1963.

The effects on Boeing were devastating to say the least.  As Boeing had more than 120 SST orders on its books, the cancellation of the SST program along with the termination of some production lines and a general downturn in civilian aircraft orders led to the loss of tens of thousands of jobs.  Although the SST’s European competitor, the Concorde, did manage to enter commercial service in 1976, only 14 of the elegant aircraft ever flew from an order book that exceeded 100 units at one point.  Concorde proved to be economically viable in the niche market it serviced–a small and dedicated customer base that gladly paid for the more expensive ticket.  In regular British service Concorde flights cost a little more than subsonic airliner first class tickets and yet made money for the British Overseas Airways Corporation and its successor, British Airways.  For a variety of reasons Air France could not keep its Concorde operations in the black.  Both countries retired their aircraft in 2003 for a number of reasons, but the maintenance costs and issues with a 30-year-old airframe had much to do with it.  The huge Franco-British effort to design and build the Concorde proved that international efforts in aerospace design and manufacture could be quite successful and pointed the way towards a more commercially viable effort that became Airbus Industries.

The Soviet Union also developed a supersonic air transport in the 1960s, beginning their design effort shortly after that with the Concorde began.  The Tupolev Tu-144 bore a similarity to the Franco-British design, but had none of the Concorde’s luck.  To judge from the McNamara documents, the threat of a Soviet SST did not play a role in the development of the American program.  First flown in 1968 (only weeks before Concorde’s first flight) to promote a political agenda touting Soviet technical superiority, the Soviet SST had a very public crash at the Paris Air Show in 1973, and a second, improved model crashed in 1978.  As a result, the Tu-144 flew only 55 flights as a passenger aircraft, although it did fly a slightly small number of flights as a freighter.  The Tu-144 was an inferior SST,  having a much shorter range than the Concorde as well as having a significantly higher landing approach speed and component reliability issues.  Political factors overruled common sense safety considerations as authorities ordered passenger flights continued despite all of the reliability problems in order to give the impression of the Soviet Union possessing a regularly scheduled supersonic air route.   All of these factors led to the construction of only 16 examples, although many more were planned.  By 1983, the Tu-144 no longer flew in commercial service.

NASA continued to fund research into supersonic transports with a variety of aerospace firms through the 1970s, although it was clear that no manufacture of an American SST was ever intended at the time.  In more recent years interest in a second generation American SST led to the ironic situation of NASA leasing one of the Russian Tu-144 survivors for a series of tests supporting the new SST research project.  Although that 1990s effort did not result in a viable research and development program, commercial interest in both supersonic business jets and passenger airliners continues to this day.  Today there is even a private company called Boom Technologies that is looking to develop its own supersonic transport–pending the gathering of good data for (you guessed it…) predicting sonic booms.  For now the only tangible reminders of the fleeting American SST program are the remains of the Boeing 2707 mockup at the Museum of Flight in Seattle, Washington, and the Seattle Supersonics professional basketball team, founded in 1967, back when Boeing’s winning design was considered a great American aerospace achievement.

2 thoughts on “What Happened to the American SST?

  1. The records of the committee are at the LBJ Library (118 boxes, most of them available for research)

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