The Boeing 2707 Supersonic Transport

By | September 15, 2017

he 2707, Boeing’s contender for any supersonic transport, may seem like ancient history now, nonetheless it was advanced then both in concept and technology. Perhaps that it was too much so.

Because the jet race had been recently won because of the UK together with the de Havilland DH.106 Comet along with the then-designated USSR with all the Tupolev Tu-104, the US stayed without choice when it wished to turn the tides from the supersonic sector, especially considering that the same two countries were preparing to launch such designs of their very own, respectively from the form in the Aerospatiale-British Aerospace Concorde as well as the Tupolev Tu-144 inside early 1960s.

Consensus in this particular early pure-jet period was that supersonic flights would be the next logical evolution with the subsonic one.

Submissions to fill this segment were created by several aircraft manufacturers from the United States. Boeing, by way of example, considered a Mach 1.8 aircraft, accommodating 227 passengers. Lockheed’s concept was more ambitious and radical. It produced a design proposal incorporating an airfoil-shaped fuselage and also a doubly compounded delta wing projected to realize Mach 3 speeds. Capacity, however, had not been unlike that surrounding Boeing’s aircraft at 218. Designated NAC-60, North American’s concept closely resembled the military B-70 Valkyrie, itself a supersonic design with canards, a compoundly-swept delta wing, and four aft-mounted engines grouped in pairs. It was also slated to the Mach 3 speed realm.

Boeing’s 2707-100, numerically considered the first on the second supersonic generation of airliners after its 707, was ultimately selected on December 31, 1966. Unlike the UK and USSR aircraft, that it was intended, through the outset, to eclipse the boundaries of traditional configuration, structure, and speed, offering a long service life.

Featuring titanium construction to resist the 500-degree Fahrenheit structural temperatures generated through the friction of their intended, 1,800-mph/Mach 3 cruise speed, it sported an adjustable geometry delta wing, which pivoted on screw jacks and titanium bearings to appeal to the extreme velocity variations, between low subsonic approach speeds inside the extended position to high supersonic cruise ones within the retracted one. Trailing edge flaps were fitted for that former component of flight.

The tailplane, with separate vertical and horizontal surfaces, was otherwise conventional.

Power would have been to have been supplied by four General Electric, wing-underside attached engines.

A full-scale wooden mockup with the supersonic airliner, meant to carry 300 passengers, was built.

Although the 113 optioned orders placed by 26 worldwide airlines seemed promising in June of 1967, the ambitious design had exceeded the technological expertise to change it into reality. Aside on the inherent instability it demonstrated during wind tunnel tests, the weight with the swing-wing aircraft was prohibitively excessive, carrying a 40,000-pound penalty, thus leaving less available with the fuel had to provide the range that carriers sought.

The immediate passenger capacity/payload reduction and/or fuel/gross weight increase solutions proved inadequate.

Supersonic flight, other than within the limited, high-altitude military form, was little understood right at that moment, for routine, scheduled commercial operations, and obstacles existed far beyond your chance board in the design teams. Public reactions, sometimes bordering on hysteria, as an example, included protests in regards to the sonic boom, its resultant property damage on the surface, the exclusion of overland flights (which reduced the opportunity airline market on the aircraft), the rise in world temperatures, the melting from the polar caps, the destruction of land- and ocean-dependent nature, along with the reduction in radiation protection through the ozone layer.

Bureaucratically, this software was continually delayed by airframe and powerplant reassessments and also the granting on the necessary governmental funding on the design.

Because the kind, as envisioned n its initial version, didn’t offer acceptable payload and range capabilities, a 2nd, the 2707-200, was proposed. Although it featured an elongated fuselage and Tu-144-resembling canards above and behind the cockpit, it weighed in at 750,000 pounds, that has been 25 percent over envisioned and greater than those of a 500-passenger 747-100, and therefore did not meet the FAA’s finalized design submission deadline.

Even its 23,000-pound fat reduction program placed its gross weight 52,000 pounds higher than the target.

While its radical, swing-wing feature was technologically feasible, it did not offer the needed parameters, because Boeing was struggling to integrate the pivots, engines, and undercarriage within an efficient engineering package.

Forced to abandon this variable-geometry airfoil concept, it produced another version, the 2707-300. Featuring a 268.8-foot overall length, it incorporated the fixed, supersonic standard delta wing planform employed by Concorde and also the Tu-144, using a 141.8-foot span with an 8,497-square-foot area. The horizontal and vertical tailplane, using a 50.1-foot height, remained conventional.

Powered by four 60,000 thrust-pound General Electric GE4/J5P turbojets, it offered double capacity and one-third more speed than its UK and USSR competitors, however, and was designed to transport 234 passengers 5,000 miles at 1,890-mph speeds at 60,000-foot service ceilings. The prototype’s 640,000-pound gross weight was anticipated to increase to 710,000 pounds on production aircraft.

Simplicity, coupled having a size reduction and also the elimination from the variable geometry airfoil’s weight and aerodynamic obstacles, generated lower production and unit costs, which, subsequently, Boeing believed might have attracted greater sales. That figure was then envisioned to as high as 500.

In October of 1968, or five months before Concorde first flew, the definitive 2707-300 was chosen because US’s supersonic transport design and construction of the prototype commenced in September on the following year, provisioning it as being the third airliner in their class to go in the market. But it never would.

Continually exposed to a design and development program that’s, on occasion, more turbulent than Concorde’s, it fought for survival.

The obstacles, as befitting of early 1960s commercial supersonic technology, were numerous and insurmountable, including escalating research and production costs, increasing gross weights, decreasing ranges and payloads, rising seat-mile costs, excessive fuel burns and engine noise, the need for over subsonic fares, plus the fear that high quality passengers would plunge to the higher-speed transport, leaving the common, subsonic ones without worrying about yield where they depended for profitability.

Limited along the way application, what kind could basically economically viable with good load factors on extended range routes.

Innovative technology, it had become increasingly apparent, couldn’t support the supersonic concept over a commercial level. Yet, blinded at times because of the need to recapture the title lost in the subsonic race understanding that “pride-goeth-before-a-fall” dynamic necessitated because of the desire to regain national prestige, this program remained aloft while using continued, albeit obstacle-ridden, granting of federal funds.

Part with this buoyancy, of course, was airline interest from the product, but, as occurred with Concorde, this started to wane, from when they were already financially strapped with orders for widebody 747s.

Public, government, and aircraft manufacturer doubts in regards to the 2707-300’s capacity to ever economically achieve its fore-claimed noise, payload, and range design goals caused declining confidence to coincide with diminishing enthusiasm for your concept.

Presidential support for just a supersonic transport program fluctuated widely. Escalating development costs spawned by increasing technological hurdlers and requiring additional governmental funding only generated increasing opposition going without running shoes. Because Tupolev seemed struggling to solve its Tu-144 problems and Concorde’s fuel-burn generated initial sales of only ten aircraft to Air France and British Airways (lots too small to pose any competitive threat), continued 2707-300 funding could not justified.

On March 18, 1971, therefore, the House voted against it, echoed a couple of days later from the Senate. Although supporters attemptedto restart this system by rechanneling the $85.3 million due to its termination into further development, and although House itself voted in favor with this action on May 12, the Senate rejected it five days later.

Fifteen percent with the first 2707-300 airframe ended up being cut at the time plus a 296-foot stretched version, to allow for 321 passengers, was then envisioned.

All three US, UK, and USSR programs ended up plagued by unprecedented opposition to new technology that lots of believed would are actually detrimental on the atmosphere, earth’s environment, and humanity. Because of the company’s tremendous technological leap, exploding development costs, and irresolvable engineering difficulties, it never had become the hoped-for reality within the US and, soon after route proving flights, the Tupolev Tu-144 itself was withdrawn from service from the USSR.

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