SM-64 Navaho
The final design was capable of delivering a nuclear weapon to the USSR from bases within the US, while cruising at Mach 3 (3,700 km/h; 2,300 mph) at 60,000 feet (18,000 m) altitude.
The original 1946 project called for a relatively short-range system, a boost-glide weapon based on a winged V-2 rocket design.
Over time the requirements were repeatedly extended, both due to the US Air Force's desire for longer ranged systems, as well as competition from similar weapons that successfully filled the shorter-range niche.
This led to a new design based on a ramjet powered cruise missile, which also developed into a series of ever-larger versions, along with the booster rockets to launch them up to speed.
With the launch of Sputnik 1 in 1957 and the ensuing fears of a missile gap, Atlas received the highest development authority.
A version of the Navaho airframe powered by a single turbojet became the AGM-28 Hound Dog, which was carried towards its targets on the Boeing B-52 Stratofortress and then flew the rest of the way at about Mach 2.
Jet engines were already widely used after their introduction in the UK, but the V-1 flying bomb and V-2 rocket represented technologies that had not been developed elsewhere.
[1] Vannevar Bush of the USAAF's Scientific Advisory Board was convinced that manned or automated aircraft like the V-1 were the only possible solution for long range roles.
A ballistic missile capable of carrying even the smallest warhead was "at least ten years away", and when asked directly about the topic, noted: In my opinion, such a thing is impossible.
NAA chief designer, Dutch Kindelberger, was convinced missiles were the future, and hired William Bollay from the US Navy's Bureau of Aeronautics to run their newly formed research laboratory.
[2] In what became known as "the black Christmas of 1946", many of the original projects were cancelled, with the remaining companies working on a single design instead of two.
The Germans were never able to get this working due to combustion instability and continued using the earlier design in spite of lower performance.
[5] Meanwhile, aerodynamicists in the company discovered that the A-4b's swept wing design was inherently unstable at transonic speeds.
Examining the work to date, NAA abandoned the boost-glide concept and moved to the ramjet powered cruise missile as the primary design.
The N-1 INS system drifted at a rate of 1 mile per hour, so at its maximum range it would not be able to meet the Air Force's 2,500-foot (760 m) CEP.
The company began development of the N-2 to fill this need and provide considerable headroom if greater range was requested.
It was essentially the mechanism of the N-1 paired to a star tracker which would provide midcourse updates to correct for any accumulated drift.
Its success at Edwards AFB and then at Cape Canaveral set the stage for the development of the second vehicle: XSSM-A-4, Navaho II, or G-26.
It incorporated numerous new technologies, Titanium components, gimballed rocket engines, a Kerosene/LOX propellant combination, and full solid-state electronic controls.
The phase III engine, XLR-43-NA-1 (also called 75K), adopted a cylindrical combustion chamber with the experimental German impinging-stream injector plate.
These ballistic missiles however would not have been possible without the liquid fuel rocket engine developments accomplished in the Navaho program.
The launch of the Soviet Satellite Sputnik in October 1957 only finished Navaho as the Air Force shifted its research money into ICBMs.
The other remaining Navaho missile was previously displayed outside the south entrance gate of Cape Canaveral Air Force Station, Florida.
This survivor was damaged by Hurricane Matthew on 7 October 2016,[11] but was restored by the Space and Missile Museum Foundation and reinstalled in March, 2021.
[12] The 1960s series Men Into Space used footage of the SM-64 and X-10 tests at Edwards AFB to depict spacecraft landings on a desert runway.
