Reading level:

Boeing 2707

Boeing Commercial Airplanes · Supersonic Transport · United States · Cold War (1970–1991)

The Boeing 2707 was the United States' attempt at a supersonic transport (SST), and one of the most expensive aerospace programme cancellations in American history. The Federal Aviation Administration selected Boeing's design in December 1966 over rival proposals from Lockheed and North American. The aircraft was meant to leapfrog the Anglo-French Concorde and Soviet Tu-144: 277 passengers against Concorde's 120, Mach 2.7 cruise against 2.04, and a swing-wing variable-geometry layout to combine low-speed handling with high-speed efficiency.

The technical hurdles proved overwhelming. Mach 2.7 cruise demanded titanium construction, with all the manufacturing difficulties Lockheed had encountered building the SR-71 a few years earlier — but at airliner volumes, where Boeing had no titanium experience. The variable-geometry wing added so much weight that the airline-required 250-plus passenger capacity could not be met. Boeing abandoned the swing-wing in 1968 in favour of a fixed tailed-delta layout (the 2707-300), but the programme was already $1.4 billion over budget by then.

Public opinion turned decisively against the SST during 1969–70 over sonic-boom and stratospheric-emissions concerns. The Senate killed federal SST funding 51–46 on 24 March 1971, and the House followed on 18 May 1971. Production tooling was scrapped. The 122 airline letters of intent — 26 firm orders plus 96 options from Pan Am, TWA, BOAC, Air France, Lufthansa and others — were all cancelled.

Cancellation of the 2707 ended American interest in supersonic civil aviation for half a century. Concorde entered service five years later in 1976 but was banned from American mainland routes until 1977 over noise concerns. As of 2026, no American supersonic passenger aircraft has reached flight, though Boom Supersonic's Overture programme aims to break that drought.

For Kids — a shorter, friendlier version

The Boeing 2707 was a super-fast passenger jet that America tried to build in the 1960s. It was designed to fly much faster than today's airplanes. Sadly, it was never finished.

The plane was meant to carry 277 passengers at once. That is more than twice as many as the famous Concorde could carry. It would have cruised at Mach 2, which is faster than a rifle bullet!

Building the plane was very hard. Flying so fast makes a plane extremely hot. That meant engineers had to use a special metal called titanium. Boeing had never used titanium for an airliner before, and it was very tricky to work with.

The wings were designed to swing back like an arrow at high speed. But those moving wings made the plane too heavy. Boeing tried a new fixed-wing design in 1968, but the project was already way over budget.

In 1971, the American government decided to stop paying for the project. People were also worried about loud sonic booms and damage to the sky. The Boeing 2707 never got to fly, and America would not try to build a supersonic airliner again for about 50 years.

Fun Facts

The Boeing 2707 would have carried 277 passengers — more than twice as many as the Concorde!
It was designed to fly at Mach 2.7, faster than a rifle bullet.
The plane needed a special metal called titanium because flying that fast makes things incredibly hot.
Its swing wings could change shape in flight, folding back like an arrow at high speed.
Boeing dropped the swing-wing idea in 1968 because the wings made the plane too heavy.
The project cost way more than planned — it went over budget by a huge amount before it was cancelled.
The American government cancelled the project in 1971 after people worried about sonic booms rattling their homes.
No American supersonic passenger jet has been built in the roughly 50 years since the 2707 was cancelled.

Kids’ Questions

How fast would the Boeing 2707 have flown?

It was designed to cruise at Mach 2.7, which means about two and a half times the speed of sound. That is faster than a rifle bullet travels. No passenger jet today flies anywhere near that fast.

Why did the Boeing 2707 never get built?

There were two big problems. First, the plane was too hard and too expensive to build. Second, people were upset about sonic booms and worried the plane could harm the upper sky. So the American government stopped the project in 1971.

What is a sonic boom?

When a plane flies faster than sound, it creates a huge wave of pressure in the air. That wave hits the ground like a giant thunderclap. People below can hear and even feel it, which made many folks unhappy about supersonic planes flying over land.

How did the Boeing 2707 compare to the Concorde?

The Boeing 2707 would have been bigger and faster than the Concorde. It could carry 277 passengers, while the Concorde only carried about 120. It was also designed to fly faster than the Concorde could.

Variants

Boeing 2707-100: Initial 1966 winning design. Variable-sweep swing wing, Mach 2.7 cruise, 277 passengers.
Boeing 2707-200: 1968 redesign with a smaller swing wing, intended to address weight problems.
Boeing 2707-300: 1969 final design. Fixed tailed-delta wing, 234 passengers. Cancelled before any prototype was completed.

Notable Operators

(Cancelled): No 2707 ever flew. 122 airline letters of intent (firm orders plus options) from Pan Am, TWA, BOAC, Air France, Lufthansa and others were cancelled when the programme ended in 1971.

Frequently Asked Questions

Why was the Boeing 2707 cancelled?

The US Senate killed federal SST funding on 24 March 1971 by a 51–46 vote, and the House confirmed the cancellation on 18 May 1971. Drivers included cost overruns of $1.4 billion above budget, engineering challenges with titanium construction at airliner scale, sonic-boom and emissions concerns, and growing public opposition.

Was the Boeing 2707 ever built?

No flight-capable Boeing 2707 was ever completed. Three full-size non-flying engineering mock-ups were built. Components and tooling for the first prototype were partially constructed before the 1971 cancellation; all materials were scrapped.

How fast was the Boeing 2707 supposed to fly?

The 2707 was designed for Mach 2.7 cruise — faster than Concorde (Mach 2.04) or the Tu-144 (Mach 2.15). That speed required titanium construction rather than aluminium because of kinetic heating, which became one of the programme's hardest engineering challenges.

Boeing 2707 vs Concorde: how would they have compared?

The 2707 would have carried 277 passengers against Concorde's 120, cruised at Mach 2.7 against 2.04, and flown farther. It might have offered better economics per seat, but its higher development cost — and the same sonic-boom restrictions that confined Concorde to overwater routes — would have squeezed the same market.

Will America build a supersonic airliner?

Possibly. Boom Supersonic is developing the Overture, a Mach-1.7 airliner targeting service entry in the late 2020s. NASA's X-59 QueSST programme is flight-testing low-boom supersonic flight to inform regulatory changes.

Sources

Boeing 2707 — Wikipedia — Source text adapted under CC BY-SA 4.0