aircraft was used for an extended equipment
bay in the test aircraft.
As the cockpit, in its snake-neck forward
fuselage, was more than 17ft (5.18m)
above the ground, specially built boarding
steps were needed and the crew had a Sky
Genie abseiling device for use in a ground
emergency. The serpent-like configuration
also meant that the nose undercarriage
leg was located 65ft (19.8m) behind the
pilot’s seat. Consequently, accurate taxi
techniques had to be relearned.
As test pilot Don Mallick noted: “A big
problem was guessing the location of the
landing gear relative to the runway. We had
to wait until the cockpit was over the edge of
the taxiway before we actually initiated a turn.”
The long nose also gave the crew a
bouncy ride on the runway and in high-
speed flight. Each four-wheel main
undercarriage had heat-resistant, metal-
impregnated tyres with complex brakes
fitted with 41 discs. However, they still had
difficulty in coping with the aircraft’s colossal
weight, often reaching temperatures of
1,093°C (2,000°F) on landing and causing
several undercarriage fires.
The first XB-70, 62-0001, AV1 was rolled
out on May 11, 1964 resplendent in itsgleaming white heat-resistant paint. As the
world’s heaviest, fastest, most powerful and
most expensive multi-engine bomber, it took
flight on September 21.
Despite careful pre-flight tests the main
undercarriage units refused to retract fully
and pilots Al White and Joe Cotton had toabandon a supersonic first flight and head for
Edwards AFB in California where the brakes
locked on touchdown, starting a fire.
An attempt at Mach 1 on the second flight
was frustrated by further undercarriage and
hydraulic problems but on October 12 AV1spent 15 minutes at Mach 1.1, returning with
areas of bare metal where the thick white
finish had flaked off. Wing-tip lowering was
tested and on the eighth flight AV1 hit Mach 2
for 40 minutes in the longest-ever supersonic
flight, totalling 74 minutes above Mach 1.
As the five-year test programme of 129
flights continued, the speed was steadily
increased. On Flight 12, at 500,000lb
(226,796kg) all-up weight, White and
Fitzhugh Fulton sustained Mach 2 for over
50 minutes, but a section of the intake
splitter broke off, damaging five of the
six engines and necessitating a no-flaps
landing at 210kts. On October 14 the ‘white
goddess’ exceeded Mach 3 for the only time,
but the sortie was aborted when a section
of delaminated skin broke off the wing. AV1
was restricted to Mach 2.6 thereafter.SECOND PROTOTYPE
The second prototype, AV2 (62-0207),
did make a supersonic maiden flight and
improved skin structure enabled it to beat
Mach 3 for 15 minutes on February 17,
1966, extended to 30 minutes on May 19.
Undercarriage problems plagued AV1 again
on March 7, 1967 when the left gear did
not pivot, leaving the four-wheel truck in a64 Aviation News incorporating Jets June 2018“...by the mid-1950s
General Curtis LeMay
demanded a Mach
3 heavy bomber to
replace the B-52 in
his mighty Strategic
Air Command”
A Convair TB-58A Hustler chase plane usually flew an inside track on an XB-70 sortie, remaining at a lower altitude. It took off (often with an XB-70
pilot in the back seat) in advance of the Valkyrie, accelerating to keep up with the white bomber as it got airborne and climbed – yet it could still only
keep pace for part of the flight. At Mach 3 the XB-70 took 13 minutes to make a 180º turn, covering a 100-mile radius in the process. NASAValkyrie AV1 moving the short distance along State Route 444 to a new facility of the National Museum of the USAF at Wright-Patterson AFB in
the early 1970s. via the NMUSAF60-65_xb70DC.mfDC.mfDC.indd 64 02/05/2018 12:35