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North American XB-70 Valkyrie — History, Specs & Stories

North American XB-70 Valkyrie prototype in flight
Aircraft Museum › Experimental › XB-70 Valkyrie

North American XB-70
“Valkyrie”

A six-engine, 250-tonne stainless-steel delta built to cruise at Mach 3 on its own shock wave — the ultimate Cold-War bomber, rendered obsolete before it ever carried a weapon, and remembered for one of aviation’s most tragic accidents.

Mach 3.1Design top speed · ~2,056 mph
2 builtPrototypes only · a third unfinished
6 enginesGeneral Electric YJ93 turbojets
1964–1969First flight · final flight to museum
Photo: NASA · Public domain
RoleExperimental strategic bomber prototypeEraCold Warمحرك6 × General Electric YJ93OriginUSA · North American AviationStatusPrototype (museum)Want to fly a fighter jet yourself?
القصة

The bomber that flew too late

In the mid-1950s the US Air Force wanted a bomber that could do what no interceptor could stop: cruise at Mach 3 and 70,000 feet, drive deep into the Soviet Union and deliver nuclear weapons faster than anything could climb to meet it. North American Aviation — makers of the P-51 Mustang and the X-15 — won the development contract in 1957. The result, the XB-70 Valkyrie, was one of the most extraordinary machines ever built: a 57-metre, six-engine stainless-steel delta finished in gleaming white, designed to ride its own shock wave across a continent.

Its central trick was compression lift. At Mach 3 the wedge-shaped forward fuselage threw a powerful shock wave, and the wing was shaped to trap that high-pressure air beneath it — so the aircraft was held up, in part, by its own sonic boom. To make it work the outer wing panels, each the size of a fighter’s entire wing, folded down as much as 65 degrees in flight, sealing the shock under the wing and restoring the directional stability a slender delta loses at high Mach.

But the world shifted underneath the programme. On 1 May 1960 an SA-2 surface-to-air missile knocked Gary Powers’ U-2 out of the sky over Sverdlovsk. If a missile could reach 70,000 feet, then flying high and fast was no longer a defence — it was a target. At the same time the intercontinental ballistic missile arrived: cheaper, faster and unstoppable, with no crew to lose. In 1961 the Kennedy administration and Defence Secretary Robert McNamara cancelled the B-70 as a bomber. Only two airframes were completed, and they flew on as pure research aircraft.

The Valkyrie’s public story is inseparable from tragedy. On 8 June 1966 the second aircraft flew a tight formation of General Electric-powered jets for a company publicity photograph near Edwards Air Force Base. An F-104 chase plane, caught in the bomber’s powerful wingtip vortex, rolled into the Valkyrie, sheared off both of its vertical tails and sent it into an unrecoverable spin. NASA test pilot Joe Walker in the F-104 and Air Force co-pilot Carl Cross in the Valkyrie were killed; pilot Al White escaped in the aircraft’s encapsulated ejection seat. It is remembered as a needless loss on a flight that existed only for a photograph.

The surviving aircraft flew on for NASA, gathering the high-speed data that fed America’s supersonic-transport research, before making its final flight to the National Museum of the US Air Force on 4 February 1969. It has stood indoors at Dayton, Ohio ever since — the only XB-70 in the world, a monument to an idea that was brilliant, beautiful and obsolete almost before it left the ground.

A machine built to outrun every threat — overtaken instead by a missile and a change of strategy.The Valkyrie paradox — the fastest bomber never meant for war
01The XB-70 Valkyrie’s cancellation: why America built only two Mach 3 bombers

The Valkyrie grew out of the 1950s Weapon System 110A requirement for a Mach 3 intercontinental bomber to replace the B-52. It was a triumph of ambition — and it was overtaken by two technologies at once. High-altitude surface-to-air missiles, proven when an SA-2 downed a U-2 in 1960, erased the safety of flying high and fast. And the intercontinental ballistic missile offered the same nuclear reach without risking a crew. Facing a bomber that was expensive, vulnerable and arguably redundant, Robert McNamara cut the B-70 to a two-aircraft research programme in 1961. The Valkyrie never carried a weapon or entered squadron service; its value, in the end, was the flight-test data it produced.

Design & Engineering

What makes it special

01

It rode its own shock wave

The Valkyrie was designed around compression lift: at Mach 3 its wedge-shaped forebody generated a shock wave whose high pressure pushed up on the underside of the wing, supplying a large share of cruise lift almost for free. Its folding wingtips — drooping to 25° subsonic and a full 65° at high Mach — sealed that pressure under the wing and clawed back the directional stability a slim delta loses near Mach 3.

02

Six engines and a skin of steel

Thrust came from six General Electric YJ93 afterburning turbojets clustered in the rear fuselage — roughly 28,000–30,000 lbf each, and one of the loudest aircraft ever flown. To survive Mach 3 heat the airframe was built largely of brazed stainless-steel honeycomb sandwich panels, with titanium — only about 9% of the structure — reserved for the hottest areas.

03

Fighting the heat of Mach 3

At Mach 3.1 the nose and leading edges reached around 330 °C and the whole airframe grew measurably longer from thermal expansion. The fuel doubled as a heat sink, soaking up heat before it was burned; a special high-stability fuel, JP-6, resisted cooking, and empty tank space was filled with inert nitrogen so the hot fuel vapours could not ignite.

02The XB-70 Valkyrie’s folding wingtips: the largest movable surfaces ever flown

Each of the Valkyrie’s outer wing panels was, on its own, about the size of a fighter’s entire wing — and they were hydraulically hinged to fold downward in flight. Subsonic they hung at roughly 25°; above about Mach 1.4 they drooped to the full 65°. This did three jobs at once: it trapped the high-pressure air of the aircraft’s own shock wave under the wing to boost compression lift, it reduced drag, and it added side-area aft to restore directional stability at Mach 3. No aircraft before or since has flown movable surfaces on this scale.

03The XB-70 Valkyrie’s honeycomb skin: the manufacturing nightmare behind Mach 3

Building an aircraft that could survive sustained Mach 3 meant inventing a structure to match. North American turned to brazed stainless-steel honeycomb sandwich panels — two thin steel skins bonded to a honeycomb core — light, stiff and heat-tolerant in theory. In practice it was punishing to build: panels could delaminate and shed under heat and stress, and at least one Mach 3 flight ended with skin peeling away from the airframe. The technique was as much art as engineering, and its difficulties were among the reasons the Valkyrie stayed a two-aircraft experiment.

Technical Data

Full specifications

Airframe & Performance

طاقم
2 (the planned bomber was to carry 4)
طول
~57 m (185 ft 10 in)
طول الجناحين
32 m (105 ft)
ارتفاع
~9.4 m (30 ft 9 in)
Max takeoff weight
~246,000 kg (~542,000 lb)
Max speed
Mach 3.1 · ~2,056 mph (~3,309 km/h)
Demonstrated top speed
Mach 3.08
سقف الخدمة
~23,000 m (~75,000 ft)
يتراوح
~6,900 km (~4,290 mi) design figure

Propulsion & Systems

Engines
6 × General Electric YJ93-GE-3
Thrust (each)
~28,000–30,000 lbf with afterburner
Structure
Brazed stainless-steel honeycomb; ~9% titanium
Fuel
JP-6, high-thermal-stability
First flight
21 September 1964
Number built
2 (a third airframe unfinished)
Programme cost
~$1.5 billion (1960s, estimate)
Cost per flight hour
No reliable public figure
04The XB-70 Valkyrie’s cost: what a cancelled Mach 3 bomber was worth

Because the Valkyrie was a government research programme and never sold, no clean flyaway unit price exists. The research effort is commonly cited at around $1.5 billion in 1960s dollars, while the original full-scale bomber programme — development plus a planned operational fleet — was estimated near $2.5 billion before cancellation; per-aircraft figures around $700 million are also quoted. All of these should be read as estimates, not audited costs. No credible cost-per-flight-hour figure for the type exists in open sources.

Timeline

From Mach 3 dream to museum piece

1954

The requirement

The USAF frames Weapon System 110A: a Mach 3, high-altitude intercontinental bomber to replace the B-52.

1957

North American wins

North American Aviation is selected to build the B-70, beating Boeing for the most ambitious bomber contract of the era.

1961

Cancelled as a bomber

SAMs and ICBMs make a high-fast bomber vulnerable and redundant; McNamara cuts the B-70 to a two-aircraft research effort.

1964

Rollout and first flight

AV-1 (62-0001) is rolled out on 11 May and makes its first flight on 21 September.

1965

First Mach 3

On 14 October AV-1 reaches Mach 3.02; the refined AV-2 would go on to nine Mach 3 flights and the programme’s top speed of Mach 3.08.

1966

The mid-air collision

On 8 June a chase F-104 strikes AV-2 during a formation photo shoot; the second Valkyrie is destroyed and two airmen die.

1966–68

Research for the SST

The surviving AV-1 flies sonic-boom, turbulence and high-speed handling research that feeds the US supersonic-transport programme.

1969

Final flight to the museum

On 4 February AV-1 makes its last flight, straight to the National Museum of the US Air Force, where it remains today.

Stories & Eyewitnesses

From the programme: twelve Valkyrie stories

Origin

The bomber that outran everything

WS-110A demanded a Mach 3 bomber that no interceptor could catch at 70,000 ft.

Read the full story
In the mid-1950s the US Air Force set out to replace the subsonic B-52 with something no defender could stop: a bomber cruising at Mach 3 and 70,000 feet. That requirement, Weapon System 110A, drove North American Aviation to design the most ambitious aircraft of the age — a jet meant to sprint across the Soviet Union faster than any fighter could climb to meet it.
Aerodynamics

Riding its own shock wave

Compression lift let the Valkyrie be held up, in part, by its own sonic boom.

Read the full story
The Valkyrie’s defining idea was compression lift. At Mach 3 the wedge-shaped forward fuselage generated a strong shock wave, and the wing was shaped so that the high-pressure air behind that shock pushed up on its underside. The aircraft was, in effect, surfing the pressure wave it created — getting a meaningful share of its cruise lift for free.
Engineering

The 65-degree folding wingtips

Outer panels the size of a fighter’s wing folded down in flight.

Read the full story
To make compression lift work and to stay stable at Mach 3, the Valkyrie’s huge outer wing panels hinged downward — about 25 degrees subsonic, a full 65 degrees at high speed. Folding them trapped the shock wave under the wing, cut drag, and restored the directional stability a slender delta loses near Mach 3. They remain the largest movable aerodynamic surfaces ever flown.
Powerplant

Six engines, one wall of noise

A cluster of six GE YJ93 turbojets made it one of the loudest aircraft ever.

Read the full story
Six General Electric YJ93 afterburning turbojets were packed into the rear fuselage, each producing roughly 28,000 to 30,000 pounds of thrust. Together they gave the Valkyrie the power to sustain Mach 3 — and made it, by many accounts, one of the loudest aircraft ever to fly, a physical wall of sound across the Mojave.
Construction

The honeycomb-skin nightmare

Brazed stainless-steel honeycomb was cutting-edge — and hard to build.

Read the full story
Surviving Mach 3 meant a new kind of structure. North American built the Valkyrie largely from brazed stainless-steel honeycomb sandwich panels, light and heat-tolerant in principle. In practice they were troublesome: panels could delaminate under heat and stress, and at least one Mach 3 flight ended with pieces of skin peeling away. The manufacturing challenge helped keep the aircraft a two-ship experiment.
Thermodynamics

Fuel as coolant, nitrogen as fireguard

At Mach 3 the airframe cooked, so the fuel absorbed the heat.

Read the full story
At Mach 3.1 the nose and leading edges reached about 330 °C and the airframe grew measurably longer from thermal expansion. The Valkyrie routed its fuel through the hot structure to soak up heat before burning it, used a special high-stability fuel called JP-6 so the heated kerosene would not cook off, and filled emptied tank space with inert nitrogen so the hot vapours could not ignite.
Strategy

Obsolete before it entered service

SAMs and ICBMs erased the case for a high-fast bomber.

Read the full story
The Valkyrie was overtaken by two technologies. The 1960 downing of a U-2 by an SA-2 missile proved that high altitude was no longer safe, and the intercontinental ballistic missile promised the same nuclear reach faster and cheaper, with no crew at risk. The result was the classic case of the right aircraft arriving in the wrong decade.
8 June 1966

The collision that shocked the programme

A publicity photo shoot ended with a chase plane in the Valkyrie’s tails.

Read the full story
On 8 June 1966 the second Valkyrie flew a tight formation of General Electric-powered jets for a company publicity photograph near Edwards Air Force Base. An F-104 chase plane, caught in the bomber’s powerful wingtip vortex, rolled into it, sheared off both vertical tails and destroyed the aircraft. It is remembered soberly as a loss that occurred on a flight flown only for a photograph.
Joe Walker

The pilot in the chase plane

NASA’s chief research pilot and a spaceflight veteran died in the F-104.

Read the full story
The F-104 that struck the Valkyrie was flown by Joseph “Joe” Walker, NASA’s chief research test pilot and an X-15 veteran who had flown to the edge of space. Drawn in by the bomber’s wingtip vortex, his aircraft rolled across the Valkyrie’s back before both went down. Walker was killed instantly — a heavy loss to American flight research.
Survival

The capsule that saved Al White

The Valkyrie’s encapsulated ejection seat sealed a pilot into a survivable pod.

Read the full story
The XB-70 used individual encapsulated ejection seats, folding the occupant back into a sealed clamshell before firing clear. In the 1966 collision, pilot Al White ejected in his capsule and survived, though his egress went badly and he was seriously injured. His co-pilot, Carl Cross, on his first flight in the aircraft, never activated his capsule and was killed.
Legacy

Grandfather of the supersonic transport

The survivor’s research fed America’s SST programme.

Read the full story
After the loss of the second aircraft, the surviving Valkyrie flew a research programme measuring sonic booms, structural response to turbulence and high-speed handling. That data fed directly into the US supersonic-transport effort and later high-speed studies — the bomber that never served ended up shaping how engineers understood sustained supersonic flight.
The survivor

The last Valkyrie in the world

AV-1 flew its final flight straight into the museum in 1969.

Read the full story
On 4 February 1969 the surviving Valkyrie, AV-1 (62-0001), made its last flight directly to the National Museum of the US Air Force at Wright-Patterson AFB in Dayton, Ohio. It has stood indoors ever since — the only XB-70 left in existence, and one of the most striking aircraft any visitor will ever stand beneath.
Gallery

The Valkyrie in pictures

The Valkyrie cruising high over the desert a jet designed to ride its own shock wave at Mach 3.
The Valkyrie cruising high over the desert — a jet designed to ride its own shock wave at Mach 3.Photo: NASA · Public domain
Seen from above with its outer wing panels drooped the folding tips that trapped the shock wave.
Seen from above with its outer wing panels drooped — the folding tips that trapped the shock wave.Photo: NASA · Public domain
The business end: the six General Electric YJ93 exhausts packed between the twin tails.
The business end: the six General Electric YJ93 exhausts packed between the twin tails.Photo: NASA · Public domain
AV-1 lifting off on a research flight with a chase aircraft alongside.
AV-1 lifting off on a research flight with a chase aircraft alongside.Photo: NASA / North American · Public domain
The 8 June 1966 mid-air collision that destroyed the second Valkyrie and killed two airmen.
The 8 June 1966 mid-air collision that destroyed the second Valkyrie and killed two airmen.Photo: U.S. Air Force · Public domain
The sole surviving XB-70A on display at the National Museum of the US Air Force in Dayton, Ohio.
The sole surviving XB-70A on display at the National Museum of the US Air Force in Dayton, Ohio.Photo: Jud McCranie · CC BY-SA 3.0
Operations

Where the Valkyrie flew

The Record

A prototype that never went to war

The Valkyrie has no combat record — it never carried a weapon, never flew a mission and never entered squadron service. Its story is written instead in flight-test numbers: the speed it demonstrated, the altitude it held, and the research data it left behind. Two were built; one survives.

Mach 3.08Top speed demonstrated in flight test
~75,000 ftResearch cruise altitude
0Weapons ever carried — a bomber that never bombed

See how aircraft that did reach the front line compare in the combat record of every military aircraft.

Questions & Answers

Everything people ask about the XB-70

Can I fly in an XB-70?
No. Only one XB-70 survives, and it is a static, non-flying exhibit at the National Museum of the US Air Force — there is no way to fly in a Valkyrie. You can, however, fly in several genuine military jets today — see migflug.com/flights-prices/.
How fast was the XB-70?
Its design top speed was about Mach 3.1 (~2,056 mph / ~3,309 km/h) at altitude. The fastest speed actually demonstrated in flight test was Mach 3.08 — making it one of the fastest large aircraft ever flown.
Why were only two XB-70s built?
The operational B-70 bomber was cancelled in 1961 after high-altitude surface-to-air missiles and intercontinental ballistic missiles made a high-fast bomber vulnerable and redundant. The two completed aircraft were kept purely as research prototypes; a third was never finished.
What happened on 8 June 1966?
During a General Electric publicity photo formation near Edwards AFB, an F-104 chase plane was caught in the Valkyrie’s wingtip vortex and collided with the second aircraft, shearing off both tails. NASA pilot Joe Walker and Air Force co-pilot Carl Cross were killed; pilot Al White survived by ejecting in the encapsulated escape seat.
Where is the XB-70 now?
The sole surviving aircraft, AV-1 (62-0001), is on display at the National Museum of the US Air Force at Wright-Patterson AFB in Dayton, Ohio, where it has stood since its final flight on 4 February 1969.
Was the XB-70 ever operational?
No. It was always a prototype and research aircraft. It never entered service, never carried weapons and never flew an operational mission — the bomber programme was cancelled before any operational aircraft were built.
How much did the XB-70 cost?
The research programme is commonly cited at around $1.5 billion in 1960s dollars, while the original full bomber programme was estimated near $2.5 billion before cancellation. These are estimates rather than audited figures, and no reliable cost-per-flight-hour number exists.
The part of the collection you can touch

You can’t fly the XB-70.
These, you can.

Some legends only live in museums — others are fuelled and waiting. MiGFlug has put civilians in real military jet cockpits since 2004.

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Related Aircraft

Continue the tour

The ContemporarySR-71 BlackbirdThe Mach 3 reconnaissance jet that actually entered service — the aircraft the Valkyrie’s speed pointed toward.Read the SR-71 storyThe PredecessorB-58 HustlerAmerica’s first Mach 2 bomber — the high-fast strategic jet the Valkyrie was meant to succeed.Read the B-58 storyThe DescendantB-1 LancerThe supersonic bomber that did reach service — by flying low and fast rather than high and fast.Read the B-1 story
Sources & Further Reading

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