1/72 AMT/Ertl XB-70

by Dave Tietjen

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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.

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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

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Photos and text © by Dave Tietjen