All The Crazy Proposed Variants Of The B-70 Valkyrie Super Bomber
The different adaptations of the B-70 included recon planes, tankers, transports, and even motherships to launch hypersonic vehicles and spacecraft.
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The Air Force's supersonic B-70 Valkyrie bomber, designed and built by North American Aviation, already holds a place of great prominence in discussions about advanced military aircraft that never made it into service and what might have happened if they did. Now, the service has published a fascinating review of proposed variants of the B-70 for use in various roles, including as a reconnaissance platform, an aerial refueling tanker, a supersonic transport, and as a mothership for launching ballistic missiles, hypersonic test vehicles, and to help get payloads into space, among others.
Air Force Material Command's (AFMC) History Office released the document, titled NAA B-70 Valkyrie Variants: A Future That Never Was..., on Nov. 23, 2020. This office regularly publishes works that provide a more in-depth look at past advanced aviation developments and other historical topics.
"Like flying cars, human colonies on Mars and so many other futuristic ideas, the 1950’s vision of the tomorrow was filled with grand ideas that are just now coming to fruition," the B-70 variant historical monograph offers by way of introduction. "As expected, aircraft engineers of the time had similar visions as they began taking their ideas from their minds, placing them on paper, then asking manufactures to bend steel and other exotic materials to create the planes of the future."
"Engineers hoped that one vehicle, one that they perceived as the last manned bomber, could change the future of aerial bombardment," it continues. "Yet, politics, money, and technological advancements put an end to the B-70 Valkyrie, a Mach 3+, nuclear-capable super-bomber. Those varying factors killed the dream even before the first vehicle rolled out of the North American Aviation assembly plant."
Some of the concepts the Air Force historians put into their compendium were put forward in support of the B-70's primary mission as a long-range strike platform. One of these is a self-contained "Alert Pod" that go underneath the rear fuselage and obviate the need for various heavy ground equipment to get the aircraft started ahead of a mission. This would have been useful, as the name implies, for aircraft sitting on short-notice alert or if Valkyries were to be dispersed to other locations with more limited support assets.
There's artwork included in the document of a B-70 fitted with an Alert Pod and also armed with a pair of Skybolt air-launched ballistic missiles, a weapon you can read about in more detail in this past War Zone feature. Another concept shows a Valkyrie carrying no less than 14 "General Purpose Missiles," a proposed common missile design that looks like a mini-B-70 and that could have accommodated different kinds of warheads optimized for different target sets.
There's a diagram showing a B-70 fitted with rotary bomb racks in its bomb bay, something that became standard on Air Forces bombers, including the B-52, B-1, and B-2, decades later. This same proposed variant, dubbed the RSB-70, with RSB standing for "reconnaissance/strike bomber," would have also had an integral reconnaissance camera package, enabling it to collect bomb damage assessment imagery itself after striking a target.
Another graphic depicts the installation of a terrain avoidance system for B-70 bombs "as surface-to-air missile capabilities of hostile countries improved, the high and fast mission of the bomber fleet became obsolete. Low-level terrain-following missions had become the new standard," according to the document. This shift in bomber concepts of operation very much went on to inform the development of the subsequent B-1.
The document also has a picture of a wind tunnel model of a B-70 fitted with a retractable parasail, a device that the Air Force, as well as other branches of the U.S. military, explored as a way to improve the short takeoff and landing capabilities of various aircraft. The parasail in this case looks much like a wing-shaped parachute, which would have provided extra lift at low speeds.
The document covers a number of non-bomber variants, as well. Some of these make good sense, at least in principle, such as a tanker version, which would have been able to top up other fuel-hungry B-70s during missions. Robert Hopkins, an Air Force veteran, author, and contributor to the War Zone, with flying time on numerous C-135 variants, including KC-135 tankers, tweeted out "Not sure, however, if I'd want to try A/R [aerial refueling] at M=3.0 [Mach 3]" after seeing this new Air Force history. "Remember Pitch X Mach = VVI [Vertical Velocity Indicator], so a sneezing while refueling would be catastrophic!"
There were also proposals for passenger and cargo transports, including a medical version "configured to include a nurses station along with patient litters for forty-eight wounded personnel." This is hardly surprising given the interest in supersonic airliners and similar aircraft at the time, which eventually gave rise to various commercial projects, including Boeing's SST and the Anglo-French Concorde.
AFMC's historians note that it's not clear if the technology at the time would have made it cost-effective to turn the B-70 into an airlifter. "In an attempt to sell a pure cargo variant, engineers truly embellished their findings by attempting to show that the cargo capacity of their supersonic transport was equal to, or better than, larger transports such as the C-133 or KC-135," the document says. "Loading of cargo through a swinging nose similar to a Lockheed C-5 or Super Guppy, or the use of access doors in the bottom and sides were just some of the problems to be overcome. The use of a detachable pod appeared to be the most logical solution."
The document also notes that the B-70 was proposed as an engine testbed to support the development of other supersonic transports or other advanced designs. One graphic shows how various kinds of engines could be mounted in the bomb bay, ranging from ramjets and pulsejets to solar, ionic, and even nuclear-powered jet engines.
The Air Force monograph also covered a number of more radical proposed variations of the B-70 design that were focused on turning into a mothership for launching various kinds of payloads inside modified bomb bays, underneath the fuselage behind specialized fairings, on top of the fuselage, or under the wings.
One such concept envisioned turning the bomber into an airborne launch platform for the Minuteman I intercontinental ballistic missile (ICBM).
It's worth noting that the Air Force actually did a real-world test of this basic idea in 1974, dropping a Minuteman missile out of the back of a C-5 Galaxy airlifter. After the missile left the C-5's cargo bay, parachutes caused it to fall into a near-vertical orientation, at which point its rocket motors fired in midair and sent it hurtling on its way to a mock target in the Pacific Ocean.
The B-70s could have been used to launch multiple kinds of hypersonic vehicles, including test platforms, such as variants of the X-15. At the same time as the Valkyrie was in development, the Air Force was also looking at hypersonic aircraft designs, such as the X-20 Dyna-Soar, that it hoped would be capable of performing various mission types in an actual operational environment.
One of these mothership proposals was interestingly referred to as the M-70 Hypersonic Experimental Launch Platform (HELP), a nomenclature similar to the M-21 version of the Lockheed SR-71 Blackbird spy plane. Lockheed developed the M-21 to launch the D-21 high-speed spy drone, which you can read about in more detail in this past War Zone piece.
The air-launched mothership version of the B-70 was also considered as a way to potentially launch payloads into space, a concept also known as two-stage-to-orbit, a role that was also proposed for the SR-71's predecessor, the A-12 Oxcart. You can read more about this general concept and the proposed AP-12 variant of the Oxcart in these past War Zone pieces, respectively. The AFMC monograph includes artwork showing modified versions of the Valkyrie launching rockets carrying spy satellites, as well as a Gemini space capsule.
"Some fanciful proposals went so far as to propose launching NASA’s Gemini manned missions from the Valkyrie mothership," the document says. "It appears engineers were desperate to come up with a mission for the aircraft and if a space-bound vehicle was small enough to be carried in this fashion, then a report was created to launch it from the B-70."
It's worth pointing out that there have been persistent rumors for decades that some form of follow-on aircraft to the B-70 was also developed for this role. This is something the War Zone has previously explored in depth.
AFMC's History Office also notes that the B-70 appears to have had at least some influence on various supersonic transport designs that came afterward, as well as other proposed hypersonic vehicle or space-launch motherships. The document highlights very broad similarities between the B-70 and concept art of an unmanned hypersonic aircraft that Boeing released more recently. North American Aviation had merged with Rockwell in 1967 to form North American Rockwell, which eventually morphed into Rockwell International. Boeing acquired various components of Rockwell International, including its aviation division, in 1996.
The Valkyrie program, as already noted, was ultimately canceled due to a wide array of factors, including technological challenges, cost growth, the Soviet Union's expanding surface-to-air missile arsenal, and subsequent changes in Air Force bomber doctrine. The Air Force only ever acquired two prototype examples of this impressive aircraft, officially designed XB-70As, one of which was infamously lost in a tragic fatal midair collision with NASA F-104 Starfighter. The remaining aircraft was subsequently used for experimental aerospace research by both the Air Force and NASA, before its retirement in 1969. It is now on display at the National Museum of the U.S. Air Force at Wright-Patterson Air Force Base in Dayton, Ohio.
Altogether, this historical monograph is a fascinating overview of the high hopes and ambitious plans the Air Force, as well as North America's engineers, once had for what has gone down as one of the most fascinating aircraft of all time, the B-70.
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