https://www.youtube.com/watch?v=fTD7RxlxJ5k
A short XB-70 Valkyrie storyThe North American Aviation XB-70 Valkyrie was the prototype version of the planned B-70 nuclear-armed, deep-penetration supersonic strategic bomber for the United States Air Force Strategic Air Command. Designed in the late 1950s by North American Aviation (NAA), the six-engined Valkyrie was capable of cruising for thousands of miles at Mach 3+ while flying at 70,000 feet (21,000 m).At these speeds, it was expected that the B-70 would be practically immune to interceptor aircraft, the only effective weapon against bomber aircraft at the time. The bomber would spend only a brief time over a particular radar station, flying out of its range before the controllers could position their fighters in a suitable location for an interception. High speed also made the aircraft difficult to see on radar displays and its high-altitude and high-speed capacity could not be matched by any contemporaneous Soviet interceptor or fighter aircraft.The introduction of the first Soviet surface-to-air missiles in the late 1950s put the near-invulnerability of the B-70 in doubt. In response, the United States Air Force (USAF) began flying its missions at low level, where the missile radar’s line of sight was limited by terrain. In this low-level penetration role, the B-70 offered little additional performance over the B-52 it was meant to replace, while being far more expensive with shorter range. Other alternate missions were proposed, but these were of limited scope. With the advent of intercontinental ballistic missiles (ICBMs) during the late 1950s, manned bombers were increasingly seen as obsolete.The USAF eventually gave up fighting for its production and the B-70 program was canceled in 1961. Development was then turned over to a research program to study the effects of long-duration high-speed flight. As such, two prototype aircraft, designated XB-70A, were built; these aircraft were used for supersonic test-flights during 1964–69.On 8 June 1966, XB-70A No. 2 was in close formation with four other aircraft (an F-4 Phantom, an F-5, a T-38 Talon, and an F-104 Starfighter) for a photoshoot at the behest of General Electric, manufacturer of the engines of all five aircraft. After the photoshoot, the F-104 drifted into the XB-70’s right wingtip, flipped and rolled inverted over the top of the Valkyrie, before striking the bomber’s vertical stabilizers and left wing. The F-104 then exploded, destroying the Valkyrie’s vertical stabilizers and damaging its left wing. Despite the loss of both vertical stabilizers and damage to the wings, the Valkyrie flew straight for 16 seconds before it entered an uncontrollable spin and crashed north of Barstow, California. NASA Chief Test Pilot Joe Walker (F-104 pilot) and Carl Cross (XB-70 co-pilot) were killed. Al White (XB-70 pilot) ejected, sustaining serious injuries, including the crushing of his arm by the closing clamshell-like escape crew capsule moments prior to ejection.The USAF summary report of the accident investigation stated that, given the position of the F-104 relative to the XB-70, Walker, the F-104 pilot, would not have been able to see the XB-70’s wing, except by uncomfortably looking back over his left shoulder. The report said that it was likely that Walker maintained his position by looking at the fuselage of the XB-70, forward of his position. The F-104 was estimated to be 70 ft (21 m) to the side of the fuselage of the XB-70 and 10 ft (3.0 m) below. The report concluded that from that position, without appropriate sight cues, Walker was unable to properly perceive his motion relative to the Valkyrie, leading to his aircraft drifting into the XB-70’s wing.[100][112] The accident investigation also pointed to the wake vortex from the XB-70’s right wingtip as the reason for the F-104’s sudden roll over and into the bomber.Specifications (XB-70A)North American XB-70A Valkyrie Ser. No 62-0001 General characteristics:Crew: 2Length: 185 ft 0 in (56.39 m)Wingspan: 105 ft 0 in (32.00 m)Height: 30 ft 0 in (9.14 m)Wing area: 6,297 sq ft (585.0 m2)Airfoil: Hexagonal; 0.30 Hex modified root, 0.70 Hex modified tipEmpty weight: 253,600 lb (115,031 kg)Gross weight: 534,700 lb (242,536 kg)Max takeoff weight: 542,000 lb (245,847 kg)Fuel capacity: 300,000 pounds (140,000 kg) / 46,745 US gal (38,923 imp gal; 176,950 l)Powerplant: 6 × General Electric YJ93-GE-3 afterburning turbojet, 19,900 lbf (89 kN) thrust each dry, 28,000 lbf (120 kN) with afterburnerPerformanceMaximum speed: 1,787 kn (2,056 mph, 3,310 km/h)Maximum speed: Mach 3.1Cruise speed: 1,738 kn (2,000 mph, 3,219 km/h)Combat range: 3,725 nmi (4,287 mi, 6,899 km)Service ceiling: 77,350 ft (23,580 m)Lift-to-drag: about 6 at Mach 2Wing loading: 84.93 lb/sq ft (414.7 kg/m2)Thrust/weight: 0.314
