altitude-capable, SA-5 ‘Gammon’ SAM
system, which was deployed to defend
the important naval port.
If technical details could be obtained of
the missile’s radar frequency, modulation,
pulse-repetition frequency (PRF),
pulse-repetition interval (PRI) and other
factors, it might be possible to develop
an e ective ECM device to reduce or
even negate its capabilities. To capture
the new signal characteristics, the SR-71’s
AR-1700 ELINT recorder was modi ed
by one of the 9th SRW’s electronic data
processing specialists, enabling the pulse
receiver’s ltering system to receive the
required signal band.
On the night of September 27, 1971,
as Maj Bob Spencer and his RSO Maj
Butch She eld sliced through the night
air with 980 in full afterburner, their
projected inbound track would carry
them over the Khrebet Sikhote Alin’
mountain region before exiting into
the Sea of Japan. The ruse worked, as
dozens of Soviet radars were switched
on to record the imminent internationalincident. Aircraft 980’s autopilot rolled
the jet into a 35° banked turn, and it
remained in international airspace
throughout. But inbound to the target
the right engine’s oil pressure dropped
to zero, forcing Spencer to decelerate
and descend immediately after the ‘take’.
They were now ‘sitting ducks’ for
any Soviet fast jets that might be
scrambled to intercept the oil-starved
‘Habu’. To make matters worse, extreme
headwinds rapidly depleted its fuel
supply, dictating a diversion into
South Korea.
Monitoring 980’s progress, the det
commander was informed by US
listening posts that several MiGs had
launched from Pyongyang, North Korea,
on what appeared to be an intercept
attempt. USAF F-102 Delta Daggers were
scrambled from a base (believed to be
Osan) in South Korea, and vectored into
a position that put them between the
MiGs and the SR-71. However, it was later
established that the MiG launch had
been unconnected with the spyplane’sOn its very fi rst operational sortie,
the SR-71 had proven its value, as it
would on countless other occasions over
the coming years.
By late summer 1968, the rst three
SR-71s deployed to OL-8 had each
amassed close to 300 ying hours from
Kadena. Although routine maintenance
of these extremely complex aircraft was
conducted at the det by dedicated, highly
quali ed maintenance teams it was time
for heavy, depot-level maintenance, which
lay beyond the capability of OL-8. At this
early stage in the SR-71’s career, it required
approximately 735 maintenance man-
hours per ight hour, which by the end of
the program had been reduced, through
experience and an increase in systems
reliability, to around 125 hours.
Thus began the rst aircraft swap-out
exercise. Codenamed Glowing Heat,
between September 12-19, 1968, serials
964, 974 and 978 were replaced by 980,
970 and 962. This complex e ort involved
more than a dozen KC-135Q tankers and
continued on a six-monthly basis for two
years. Following this, as the tempo of the
Vietnam War increased, from December
1970 until June 1973, a fourth SR-71
was deployed to the det. Advances in
aircraft reliability, and an enhanced
maintenance capability, increased an
SR-71’s deployment time to 14 months,
and these were staggered over a month
to reduce the impact on operations.Back to the USSR
Although at this time South-east Asia
remained the SR-71’s primary theater of
operations, this wasn’t exclusively the
case. When US intelligence obtained
details of a large Soviet naval exercise
to be held near Vladivostok, they
calculated that such an event would
generate a rich source of intelligence
data, and an SR-71 was the ideal vehicle
to stir the Soviet eet’s defense systems
into action. In addition, national security
o cials were interested in obtaining
fresh data on the signal characteristics
of the Soviet Union’s new, ultra-high-Above: Once the
compressed air
system spooled
the engine up, the
pilot moved the
applicable throttle
forward to the idle
position, checked
for immediate
fuel fl ow increase
and ignition
occurred within
20 seconds as
the specially
developed
triethylborane
(TEB) lit the fuel,
as seen from the
emerald-green
fl ash.
Paul F. Crickmore
Below: With
throttles fully
forward, both
afterburners
rarely lit
simultaneously,
and opposite
rudder was
required to keep
the aircraft on the
centerline.
Paul F. CrickmoreFEATURE ARTICLE // ‘SKUNK WORKS’ AT 75
104 April 2018 //^ http://www.combataircraft.net
100-109 SR-71 Skunk C.indd 104 16/02/2018 10:12