In 1955 the USAF issued the specification GOR No. 48 calling for a supersonic bomber, with 6,000 miles range, to penetrate the Soviet air defense system. Six months later, the company North American Aviation Inc. proposed a six-engine canard-delta aircraft capable of cruising at Mach 3+ while flying at 70,000 ft. (21,341 m).
It was expected that the new bomber would practically be immune to the cannon-armed Soviet interceptors, but it had also been planned to install a five-element defensive system embodying active and passive warning devices to be capable of noise jamming 30 Soviet radars operating simultaneously, threat evaluation equipment, electronic countermeasures, infrared countermeasures as chaff dispersing rockets and plastic smoke to screen the engine exhaust.
In August 1958, the proposal had been approved by the USAF under the codename Weapons System 110A and was expected to enter service in 1963 as the B-70 Valkyrie.
On February 26, 1955, the Soviet CPSU Central Committee ordered the development of the weapons system Uragan-5, for the automatic guidance interception of enemy supersonic bombers flying at 82,000 ft. (25,000 m) and 1,234 mph (2,000 km/h).
The system was to be formed by 59 early warning ground radar stations with P-14 (Tall King) VHF radar sets and 400 km of detection range, digital control computer, IFF interrogation system, command data link and a point-defense interceptor with 120 km combat range.
The second generation of Soviet surface-to-air missile systems S-75 (SA-2 Guideline) was designed with the aim of correcting all the SA-1 shortcomings.
Each SA-2 launch site was capable of 360-degree coverage, to cope with the threat posed by a single bomber and consisted of six launcher pads deployed in a circular pattern around the RSNA/SNR-75 Fan Song fire control radar, with 120 km range. All the Guideline components were mounted on wheeled vehicles.
The V-750 rail-launched missile with Mach 4.0 top speed, 35 km range and 27,000 m ceiling, used one Kartukov solid fuel rocket booster to accelerate off its launcher and one bi-propellant rocket motor sustainer, with 3,000 kg peak thrust and 25-60 seconds burn time.
To offset the accuracy limitations of Fan Song guidance, the missile was fitted with 5E11 Shmel radio proximity fuse and 11D fragmentation warhead, with 250 kg of conventional explosive. The warhead blast radius for severe damage at high-altitude was 250 m, due to the rarified atmosphere.
Fan Song could simultaneously direct three missiles against a target to achieve acceptable success possibilities.
The new P-12 A (Spoon Rest) early warning radar had 275 km acquisition range and 32,000 m ceiling.
In spring of 1958 the Guideline system was deployed in 600 launch sites around Moscow, Leningrad, and Baku.
In the early 1960s the final U-2 overflight of the Soviet Union U-2 was planned under the code name Grand Slam.
The Pakistan-Norway nine hours flight was 3,800 miles long, with 2,900 miles over the Soviet airspace overflying Tyuratam, Chelyabinsk, Kyshtym, Sverdlovsk, Kirov, Severodvinsk, Kandalaksa, Murmansk, Polyarnyy and Bodo-Norway.
On May 1, 1960, one U-2 took-off from Peshawar at 6:26 AM, and once airborne the spy plane turned toward the Afghanistan border flying at 66,000 ft. (20,120 m).
The U-2 was spotted by Soviet radar over Afghanistan while it was still at fifteen miles of the USSR border.
An alert was called, all civilian airliners were grounded and all V-PVO airfields, SAM sites, radar stations and command posts over the southern Soviet Union were placed on full combat alert.
The U-2 was tracked by multiple PVO radars, thirteen fighters scrambled around Tashkent, and they carried out zoom-climb attacks in an attempt to catch the intruder despite the fact that experience had demonstrated that the MiG fighters were unable to intercept the U-2.
The intruder was lost on radar and reacquired over Tyuratam flying at 70,500 ft. (21,493 m)
Two MiG-19P fighters made an unsuccessful attempt to get into firing position, vectored by ground radar, but they could only ascend to 58,000 ft. (17,682 m).
The PVO staff predicting that the U-2 was heading toward Sverdlovsk, and all the SAM SA-2 sites of 4th Independent Army and the fighter units based in the area were instructed to down the intruder “whatever the cost”.
Captain Mentiukov, the pilot of one Sukhoi Su-9 Fishpot fighter that made a refueling stop at Kolcovo airfield, was ordered to intercept the U-2.
The Su-9 was in ferry configuration, it carried no air-to-air missiles, and none were available at Kolcovo, but Mentiukov received order to ramming the spy plane.
The mission was suicidal because the pilot did not have high-altitude pressure suit.
Instead of using the old Taran tactics, Mentiukov tried cutting the target trajectory and putting it out of control with the trail turbulence. This type of attack had been successfully used by a D.H. Mosquito FB VI of the 418th RAF Squadron to destabilize a V-1 flying bomb in June 1944.
The U-2 had to fly very near their never-exceeded speed and the margin with the stall speed at 70,000 ft. (21,341 m) was only 12 mph. Exceeding any of both limits could cause transonic airflow separation at the wings and structural damage.
The Su-9 was guided by ground control radar, but its zoom-climb attack was unsuccessful and overshot the target by 26,000 ft. (7,927 m).
The first salvo of SA-2 surface-to-air missiles failed because the U-2 was already out of range by the time the missiles reached its altitude.
When the intruder entered the engagement area of the next launch site at 08:36, only one SA-2 was fired due to fire control malfunction. At 70,500 ft. (21,493 m) over Sverdlovsk the missile warhead detonated near the U-2 damaging the tailplane. The aircraft was destabilized losing its wings due to the g-forces and the pilot Francis Gary Powers was captured, creating an international incident.
Meanwhile two MiG-19 P Farmer B fighters were airborne and approaching the engagement zone, but their IFF transponders did not work, and Lieutenant Safronov's plane was destroyed by the third salvo of missiles.
The incident was kept secret for many years.
On March 7, 1957, the MiG OKB was tasked with the design of the new interceptor, under the codename Ye-150. The prototype was flown on July 8, 1960, reaching a top speed of 2,816 km/h (Mach 2.65) and 73,000 ft. (22,500 m) ceiling.
The combat version Ye-152-1, that reached 2.28 Mach, armed with two underwing air-to-air missiles Mikoyan Raduga K-9-51, flew on May 16, 1961.
On July 7, 1962, the aircraft established the absolute speed record flying at 1,666 mph (2,681 km/h) under the fictitious designation Ye-166.
MiG Ye-152-1 technical data
Wingspan: 29 ft. (8.79 m), length: 64 ft. (19.65 m), wing area: 467 sq. ft. (42 sq. m), take-off weight: 31,678 lb. (14,350 kg), maximum speed: 1,883 mph (3,030 km/h), service ceiling: 74,358 ft. (22,670 m), power plant: one Tumansky R-15-300 turbojet rated at 10,210 kg thrust with afterburner, armament: two K-9 missiles.
The Valkyrie program suffered numerous delays due to inexperience with the new heat-resistant materials, as well as political and budgetary reasons. When the prototype XB-70 AV-1 was flown on September 21, 1964 the Soviet air defense system was already so consolidated that the WS110A specification was meaningless, and the B-70 was cancelled by the Kennedy Administration.
In August 1958, the North American project office submitted the proposal Defensive Antimissile System (DAMS) using air-to-air missiles launched by the Valkyrie.
The Defense Feasibility Study was completed in March 1959 and published by the Air Proving Ground Center-Eglin AFB the same month the U-2 incident occurred.
In 1948 the first experimental AAM-A-2 air-to-air missile was launched and entered in service with the USAF in 1955 as the Hughes AIM-4 Falcon.
The original purpose of the Falcon was a Mach 3.8 self-defense weapon for the B-52 bomber and was shortly revived during the B-70 development. The rail-launched missile was not particularly maneuverable and needed to be pointed in the right direction of the target.
Due to the B-70 speed the Falcon could just be used against any threat coming from its forward hemisphere, but the Valkyrie would have to defend itself against threats from all direction with spherical coverage.
The Falcon was a cylindrical rocket with four delta wings. Would it have been thrown sideways from a B-70 flying to Mach 3 it would have been destroyed by the crosswind shock waves.
North American proposed the Weapons System WS-740A, a wingless lenticular-form rocket with omnidirectional launch capabilities, capable of engaging incoming missiles at relative speeds of Mach 10 and being able to survive and maneuver at 250g accelerations.
The project was awarded to the Convair Division of General Dynamics Corporation, under the codename Pye Wacket in June 1959.
A general aerodynamic evaluation was conducted to determine the technical feasibility of lenticular cross section/circular planform configuration. Wind tunnel tests with several 1/3 scale models were conducted in the Arnold Engineering Development Centre.
The results indicated that the lenticular configuration with blunted trailing edge, sharp leading edge and modified tangent contours, have best aerodynamic characteristics than the symmetrical lenticular cross section, and the most desirable volume distribution for the propulsion system.
The lenticular configuration was efficient at hypersonic velocities with good maneuverability at altitude. Additional tests demonstrated that the aerodynamic controls are not suitable for use in the omnidirectional launch phase of flight, due to the necessity of alignment with the relative wind.
One reaction-jet control system was used, control in yaw, roll and pitch could be obtained by means of the thrust forces generated by four nitrogen-injected binary thrusters, with exhaust through the top and bottom surfaces of the disc.
Pye Wacket had an inertial midcourse guidance system with terminal infrared homing. The Redeye IR seeker was mounted in the leading edge behind an IR window with a look angle of 40 degrees and cooling system.
The USAF determined that internal carriage of eight wingless missiles could be installed in the Valkyrie with no range penalty.
The weapon was to be structurally rigid to withstand extremely high launch accelerations, rapid change of thrust direction for quick maneuver, maximum flight duration of 50 seconds, cruising at Mach 6.5+ and terminal velocities of Mach 10.
The expected aerodynamic heating of 3,300 ºF at 11 seconds of flight, requires the use of a leading edge made of Pyrographite. The outer skin of the disc was made of polyester resin, with Titanium B-120 alloy honeycomb core, protected by a layer of Teflon ablating material to restrict skin temperatures to under 800ºF. The internal structure was made of magnesium-alloy.
Three Pye Wacket configurations were proposed in 1961:
60-inch diameter, 21 per cent thickness-to-chord ratio configuration
Power plant: three Thiokol M58A2 solid-fuel rocket motors with 10,200 lbf thrust each. Launch weight: 830 pounds. Warhead: one W54 nuclear device with 50 pounds weight. Range: 100,000 ft at 60,000 ft altitude.
60-inch diameter, 14 per cent thickness-to-chord ratio configuration
Power plant: one integral pancake-shaped solid-fuel rocket motor with 9,700 lbf thrust. Launch weight: 581 pounds. Warhead: 20 pounds of H.E. with impact fuse. Range: 120,000 ft at 60,000 ft altitude.
36-inch diameter, 21 per cent thickness-to-chord ratio configuration
Power plant: one integral pancake-shaped solid-fuel rocket motor with 5,000 lbf thrust. Launch weight: 200 pounds. Warhead: 20 pounds of H.E. with impact fuse. Range: 50,000 ft at 60,000 ft altitude.
