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October
14th, 1965 (Part
Two).
Feeling secure that
AV/2 would not have the same skin separation problems of
AV/1, extensive performance and control testing at speeds
above Mach 2.7, but below Mach 3 were the next step. This
data was important for determining what the handling
abilities of the SST (intended to cruise at around Mach 2.7)
would be like. Already, it had become obvious that no SST
could be expected to use the established approach routes to
airports! Some sonic boom testing (although not as extensive
as later on) was also conducted. The viability of the SST
depended on high-altitude sonic booms being greatly
dissipated as compared to lower altitude sonic boom effects.
To the dismay of many, early tests indicated this would not
be the case.
At this point in
March, 1966, AV/1 was getting ready for her 37th flight,
with Van Shepard as pilot, and Joseph Cotton as co-pilot.
Control and performance tests were on the flight plan -- but
soon it was a different performance being tested.
Halfway through the
planned flight, BOTH hydraulic systems -- primary and
secondary -- began to fail. Shepard quickly brought the
Valkyrie home as Cotton extended the landing gear. No green
indicators came on, followed by a call from the chase plane
that there was trouble with both sets of main gear. On the
left side, the gear hadn't fully lowered before rotating to
meet the direction of travel, leaving her rear wheels
higher, rather than lower, than the front set of
wheels.
The right side gear
was in worse shape -- it hadn't lowered at all before
rotating. Even more alarming, it hadn't rotated completely
in line with the direction of travel, although it was close.
The emergency backup system failed to correct the problem,
and with overall control of the aircraft rapidly coming into
question, engineers on the ground had to think quickly, or
face losing an aircraft that was a half-billion dollar
investment.
After what must have
seemed like hours in the cockpit, engineers on the ground
called up to the pilots with their plan. Shepard would land
the Valkyrie on the dry lake bed, so there would be plenty
of room to ease to a stop. It was felt that, on touchdown,
the left side gear would level itself out, the sheer weight
of the XB-70 forcing the gear into its normal position. As
for the right gear... being behind the centreline of the
main strut, it was unlikely that the gear would level out,
but hopefully the landing would at least cause the gear to
finish swinging into the direction of travel, and the
wingtip would still clear the ground, although the right
side would be much lower than the left.
Van Shepard gingerly
set AV/1 down on the lake bed, and each main gear did what
the engineers expected. So now, the plane was down and
rolling, but she wanted to turn sharply to the right --
threatening to ground loop, which, although likely not fatal
to the pilots, would likely destroy the aircraft. So Shepard
kept applying power to the number six (farthest right side)
engine to help keep the XB-70 somewhat straight, but at the
same time, he couldn't use too much power, or the plane
would never stop!
Finally, after
rolling almost three miles, the XB-70 completed her landing
run, which, when viewed from above, looked like an
upside-down letter "J" because the XB-70 had not just swung
over half a mile to the right side, but by the time she came
to a stop, she had turned 110 degrees, almost pointing in
the direction she had come from! Only the huge size of the
lake bed made this landing possible --anywhere else, the
XB-70 would have been far off the runway and likely into
buildings and hangars (another decidedly undesirable
event).
Later that same
month, to the joy of a great many Texans, it was decided
that AV/2 would be flown down to Carswell AFB for the
airshow there. It was to be the only airfield that Ship Two
would fly to and return.
With Fitz Fulton at
the controls, the Valkyrie spent only 13 minutes at Mach 2.6
before slowing up, winding up at 6,000 feet over Carswell
AFB just 59 minutes after takeoff! For the next half hour,
AV/2 thundered around the skies of Texas before landing. The
return flight two days later was the only flight during the
entire program where performance data was not recorded, as
Cotton (in the pilot's seat) and White flew back at subsonic
speeds, taking a little over three hours to return to
Edwards.
Then AV/2 was off to
heat soak for even longer times -- over 30 minutes -- at
speeds of Mach 2.8 and 2.9, as well as flights of 16 and 20
minutes at Mach 3. Flights 35 and 36 were used to get a
better look at the causes and ways to remedy unstarts at
speeds above Mach 2.5.
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