History
of the RB-70C
With the complete success of the Soviet Union
’s invasion of Afghanistan and subsequent bloodless conquest of Iran
in the closing years of the 1980s, the Cold War had never been hotter.
American strategic planners recognized the increased likelihood of a
nuclear exchange if the threatened closure of the
Strait of Hormuz
cut off the flow of oil to the West from the
Persian Gulf. The START II treaty was worthless
paper, and the Soviets had expanded deployment of their SS-24 “Scalpel”
rail-mobile ICBM system, taking advantage of the thousands of miles of railroad
track deep in the Siberian interior, with the missile trains hiding in tunnels
and specially-designed bunkers all along the tracks.
Thus the immediate US Air Force need for a manned bomber to act as a
“hunter-killer” of these mobile ICBM’s was met by the quick return to
production status of the B-70, which had been designed thirty years earlier, but
cancelled as an unnecessary waste of money in the 1960s.
The new aircraft was named the RB-70C Valkyrie II.
Many of the old airframes’ systems were
updated, especially its six more powerful and more fuel-efficient General
Electric J93-GE-9 engines, which allowed increased flight time at a cruise speed
in excess of Mach 3, and at an increased altitude of over 100,000 feet.
This largely eliminated the risk of Soviet surface-to-air missiles, as
had been observed with the SR-71 overflight program years earlier.
Air-to-air refueling capacity was added, although there was still a need
for a high-Mach tanker to accompany the attack aircraft.
Computerized flight and engine inlet controls and advances in the
understanding of the “compression lift” concept allowed the updated B-70 to
have much greater maneuverability at Mach 3, permitting a more varied course to
be flown during a loitering patrol high over Soviet airspace.
A 5 degree wing dihedral as originally produced in the second prototype
was retained. The final
modification to reduce the risk of air defense counterattack was a
radar-absorbent coating applied to the bottom only of the aircraft.
There were stations for four aircrew
members, each with escape capsules in the event of a need to eject from the
bomber. The pilot was also aircraft
commander; the co-pilot managed communications and the limited defensive
systems; and the two back-seaters dealt with the complex flow of data from the
onboard reconnaissance systems. One
offensive systems operator also doubled as bombardier, tasked with targeting
decisions and settings for the bombs, as well as primary photoreconnaissance
analysis, while the other operator handled radar data systems and assisted with
the photographic data. All these
systems were heavily computer aided, and real-time links with satellite recon,
other patrolling RB-70Cs, and SAC were utilized to keep the attackers
coordinated and assist in targeting the widely dispersed SS-24s.
Onboard reconnaissance systems to accomplish
this represented a real break-through in manned bomber mission strategy.
Photographic data was collected initially with a wide-field ultra-high
resolution digital camera system mounted just under the cockpit, using both the
visible and infrared spectra. The
job of more detailed imaging could then be handed off to narrower field, more
highly magnified cameras in four windows farther aft on the front fuselage.
This optical viewing port setup was very similar to that used in the
SR-71 Blackbird, although the imaging equipment and processors were all newly
developed. Truly revolutionary,
however, was the ability to include a suite with 2D X-band active aperture
radar, inverse synthetic aperture radar, and a moving target indicator mode (as
modeled by the JSTARS system) in a long pod directly under the rear portion of
the upper fuselage. With this
sophisticated radar high over enemy territory, any and all railroad tracks could
be monitored continuously, with trains mapped and sighted in, watching for any
sign of missile container pre-launch activity, with the capability to respond
immediately.
Offensive response involved the ability to
launch B61 Mod 7 thermonuclear bombs each with guidance equipment similar to the
JDAM device. Up to eight of these
were carried internally in fore and aft bomb bays located in the center of the
lower fuselage. Bay doors opened by
sliding back or forward to avoid the door entering the supersonic air stream.
Each free-fall bomb allowed variable yield from 10 kilotons to 340
kilotons, and was individually targetable using rough GPS coordinates calculated
by onboard computers linked to the reconnaissance package. There was no real
need for very high delivery accuracy, as the intended target was certainly not
hardened. As a counter to the
possibility of missile launch before the bomb could fall to the low altitude
required for destruction of the train, the bombardier was able to reprogram the
device to detonate at whatever altitude was calculated for the crossing of the
ICBM’s and the bomb’s opposite trajectories, enabling the resultant shock
wave to destroy the missile during the boost phase.
The anticipated mission profile involved
launching from USAF bases in the continental United States at the first sign of a possible nuclear attack.
The aircraft would move quickly to staging areas just outside Soviet
airspace, refuel, and dash at high Mach to their respective patrol zones,
establishing satellite communication links with SAC HQ and each other.
Each RB-70 would be accompanied by two pairs of F-12B’s (the new
fighter version of the SR-71) picked up from air bases farther north and
assigned the escort role ahead of and behind the Valkyrie II at lower altitude
to fend off any potential MiG-25 sortie. A
random search track would be flown while monitoring for evidence of trains
bearing SS-24 missiles, and, if found, those trains could be eliminated.
Recovery would be at any available air base.
The first operational unit equipped with the
RB-70C was the 97th Bombardment Wing at Eaker AFB,
Arkansas. This assignment aborted the
planned closure of the base and reversed the redesignation plan for the unit to
become the 97th Air Mobility Wing.
The 96th Bomb Squadron was shifted from Barksdale AFB,
Louisiana, to Eaker AFB to assume this vital alert mission – the unit emblem of a red
devil holding a bomb and thumbing its nose at the enemy below truly representing
the task assigned these aviators.
Click on
images below to see larger images
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The
Kit
Many if not most of you are familiar with
the venerable AMT/Ertl 1/72 XB-70 injection molded kit.
Long out of production now, it nonetheless can be found with only a
moderate amount of effort, as even the “limited edition” version, with its
poster and cheesy little plaque, had a production run of 15,000.
Make plenty of room for this momma – it is 33 inches long, joining the
ranks of the 1/72 B-36 and B-52 as one of the largest kits in this, or any
other, scale. Panel lines are
raised and detail is pretty restricted, but it’s not unacceptable; options
include a raised or lowered windshield ramp and wingtips that can be posed up or
dropped to the full supersonic angle – be aware that the landing gear will not
keep the wingtips off the surface it the tips are down, although certainly the
wings would never be in this position in reality except in flight or on stands
in a hanger. No provision for a
bomb bay or other weapon carriage is included.
Every
example of this kit I’ve seen built is a replica of the first prototype, Air
Vehicle Number 1 (A/V-1), which survives today at the
USAF
Museum
in
Dayton
,
Ohio
. They are therefore finished in
the all-white paint scheme used on both airframes built, and typically show
decals as provided in the kit. I
wanted to do something completely different.
Kit
Modifications
My first task was to try to duplicate the 5
degree dihedral of the wings which was built into A/V-2 and would have been in
all subsequent airframes. To do
this I penciled a line along the junction between the lower fuselage box and the
wing panels, and then deeply scribed a groove in the inner surfaces of both
upper and lower wings, such that it was not visible on the outside.
Then keeping the central part of the piece flat, I folded the outer part
of the panel up or down the desired 5 degrees and then smeared fast-curing epoxy
into the groove to hold its bent shape. Next
I glued the top and bottom panels together on each side to keep the dihedral
intact before cementing the right and left wings together (opposite the
order from the directions). This
did open gaps at the elevon seams and especially along the lower central seam,
but the lower fuselage box almost completely covers the large gap, and filler
took care of the others.
The next job was creating a bomb bay in that
lower fuselage box. A rectangular
section in the area set aside for bomb carriage was cut out with my Dremel and
trimmed to size with a sharp knife and sanded smooth.
Thick sheet styrene was fashioned to represent the bay door slid back to
open the bomb bay, and walls were cut from the same sheet and cemented in place
to box in the cavity. Spare parts
from a 1/72 Italeri B-58 were used for the modified nuclear bombs and their
mounting racks glued to the top of the bay.
Next I opened cut-outs for the camera
windows in the bottom of the forward fuselage and fitted slightly curved clear
styrene ports from a cast-off paint jar into the openings after polishing and a
coat of Future. The radar
“canoe” was made from styrene tube cut in half lengthwise and then capped by
half-round pieces of large diameter sprue.
Putty was used to smooth these contours, and the antenna housing glued to
the centerline of the fuselage. Other
small antenna pieces and blisters were attached, and a refueling door scribed in
the top of the fuselage.
Wing tip panels were folded down as they
would be in Mach 3 flight just because I think they look cool that way – a
foam block painted black holds the tips off the table as the model sits on its
landing gear. Since the wingtips
were down, I chose to put the windshield ramp in the up position.
The color scheme is an attempt to depict a
natural stainless steel appearance on the topside, and a gray, low visibility,
radar absorbent finish on the bottom. Decals
are a mish-mash of kit supplied markings and spares.
Wing-walk stripes are from the 1/48 Monogram B-58 and by chance fit
perfectly. A SAC shield is still proudly displayed on the fuselage port
side; other emblems are for the 97th BW and 96th BS.
Conclusion
This beast was a lot of work, but it was
great fun to modify and complete a truly unique model aircraft, and to dream up
a (sort of) plausible mission for what was an unfortunately disrespected
would-be warbird. Perhaps my
example will stimulate others to pull their XB-70 kit out from the back of the
closet and try their own version.
Dave
Click on
images below to see larger images
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