An Up-Close Look at America’s Forgotten Supersonic Bomber – CNET [CNET]

The Valkyrie was born in era when it was thought that the best way to penetrate enemy airspace was to fly higher and faster than interceptor aircraft.

The Air Force wanted an aircraft with the speed of the supersonic B-58 Hustler, but a bomb load closer to the huge B-52 Stratofortress. North American Aviation won the design competition.

Top speed was Mach 3.1, or about 2,056 mph at over 70,000 feet. Few aircraft, even today, could keep up with the XB-70.

The XB-70 used afterburners to reach its top speed. Afterburners are highly inefficient at low speeds, but they’re excellent at Mach 3. 

The XB-70 had a range of more than 4,000 miles. Aerial refueling was planned, but the project never got that far.

Part of the XB-70’s supersonic cruise efficiency came from its adjustable wingtips, which tilted down to let the Valkyrie sit on its own shockwave. This increased lift and helped reduce drag.

The initial design was for a pilot, co-pilot, navigator and bombardier. The latter two positions were eliminated when it transitioned to a research aircraft.

As modern, futuristic even, as the aircraft looks, check out the cars in the background. The car in-between the two trucks looks like a 1953 Ford. On the left is a Ford Country Squire from about 1968.

There are tons of dials and levers to control this six-engine supersonic machine.

During its short career, only seven people flew the XB-70.

Here’s a closer look at the wingtip controls.

This is where the navigator and bombardier positions would have been. Behind the camera is the cockpit.

President John F. Kennedy canceled the B-70 program in 1961. By that point, the USSR had perfected supersonic surface-to-air missiles that could reach the high-flying XB-70. Two prototype aircraft were given to NASA for testing in the development of larger, supersonic aircraft.

The first XB-70 built had a few issues that led to instability at high speed. These were fixed with the second aircraft built. The majority of Mach 3 test flights were performed by the second XB-70.

Three drag chutes were used to slow the XB-70 down when landing. They were stored in the upper fuselage, just ahead of the engines. 

The Air Force and North American had grand ideas for the potential of a huge and fast aircraft. Here is an artist’s idea for using the XB-70 as a launch platform for orbital and sub-orbital spacecraft.

In this version, a lightly modified XB-70 would launch a Minuteman II missile. Typically, these were meant to be launched from fortified bunkers in the Midwest.

Much of the XB-70’s NASA testing was to study the possibility of an American-made supersonic transport (SST) to compete with the Anglo-French Concorde and Soviet Tu-144. North American pushed hard for its design, going so far as to add fake windows to an XB-70 during one maintenance period.

After the crash of the second and more capable XB-70, the original was put back in service for a few years. Lacking the performance of its sister aircraft, it was soon retired. Its last flight on Feb. 4, 1969, was to Wright-Patterson Air Force Base in Ohio. It was then towed on public streets to the National Museum of the US Air Force.

It’s easy to see here how huge the XB-70 is, compared to other supersonic and experimental aircraft. 

The canards, the small wings just aft of the cockpit, helped maintain control of the huge airframe. Below, the sharp air intakes helped create the shockwave crucial for compression lift.

Not only were the intake’s interior walls variable to alter the shockwave at speed, but also the walls were porous to vent turbulent air and help ensure the engines got smooth, supersonic air.

On the lower left is one of the aircraft used for research after the XB-70 was retired: a Lockheed YF-12.

The XB-70 featured six General Electric YJ93-GE-3 turbojet engines that provided 28,000 pounds of thrust each.

The use of compression lift on the XB-70 led to research on lifting-body aircraft, like the Martin X-24B here.