Вы здесь

Lockheed A-12: The CIAs Blackbird and other variants

Lockheed A-12: The CIAs Blackbird and other variants
Photographed during a test flight on December 22, 1962, Article 123 (60-6926) was the third A-12 to be built. The innovative “blended body” design merging both the fuselage and engine nacelles into the wings to reduce RCS is clearly depicted. (Lockheed Martin)A-12 chief test pilot Lou Schalk (center, in flight suit) is congratulated by “Agency” and Lockheed officials following successful completion of the A-12’s first “official” flight on April 30, 1962. Note the F-104 Starfighter chase plane in the background. (Lockheed Martin)

Two days later, Schalk successfully completed a trouble-free first real test flight lasting 35 minutes — for which the SAS dampers remained switched on!

Over the next few months Article 121 was joined by more of its stablemates. Article 122 (60-6925) arrived on June 26, but was destined to spend three months conducting ground radar tests before taking to the air. Aircraft number three (Article 123; 60-6926) arrived in August and flew in October. In November the two-seat pilot trainer (Article 124; 60-6927) was delivered, which was planned to help smooth transition training. The aircraft was to have been powered by J58 engines, but as engine production problems persisted, it was decided to equip the two-seater with J75 engines and let the checked-out pilots go on to high-Mach flight on their own. Therefore the AT-12 trainer aircraft, nicknamed the “Titanium Goose,” undertook its maiden flight in January 1963 fitted with the less-powerful engines. Aircraft number five (Article 125; 60-6928) was delivered to the site on December 19, 1962.

The Cuban Missile Crisis once again demonstrated the U-2’s vulnerability to SA-2 attack in spectacular fashion when Air Force Maj Rudy Anderson was shot down and tragically killed during a reconnaissance mission over the Caribbean island on October 27, 1962. But still there was no sign of Oxcart entering service.

On January 15, 1963, the first flight of an A-12 powered by two J58s finally occurred and by the end of the month ten engines were available and the test program began to gain momentum. The biggest hurdle facing both test pilots and engineers was perfecting the air induction system, designed to vastly augment engine thrust. To achieve Johnson’s design goal of sustained Mach 3.2 flight, the air inlet spike’s aft-movement, together with the precise position of various bypass doors, had to initially be manually programed extremely accurately by the test team to ensure that the terminal shock wave was positioned in exactly the correct position in order to stabilize airflow in the inlet duct for future flights. When these parameters were finally achieved, the A-12’s thirst for fuel — particularly during the transonic phase of acceleration — was notably reduced. In all, it took 66 flights to extend Oxcart’s speed envelope out from Mach 2.0 to Mach 3.2.

1. A-12 Serial 60-6933, this aircraft was the tenth A-12 built. 2. AT-12, The two-seat A-12 pilot trainer. 3. YF-12A, Serial 60-6935, as it appeared when operating with NASA, configured with instruments for a series of “cold-wall” experiments. 4. SR-71A The A-12’s replacement as the United States’ Mach 3 reconnaisance aircraft. The two-seat SR-71 had a radar antenna in the nose, equipment bays in the underside of its chine, a longer “boat-tail,” and a circular “window” in the upper fuselage for its astroinertial navigation system.Article 123 was the first of five A-12s lost in accidents. The aircraft crashed on May 24, 1963, whilst being flown by Ken Collins during a subsonic flight test — the airframe had accumulated just 135.3 flight hours. (Lockheed Martin via Tony Landis)

But success came at a price. On May 24, 1963, Ken Collins was forced to eject from Article 123 during a subsonic engine test sortie, following an aircraft pitch-up and subsequent loss of control. The cause was found to be ice encrustation in the pitot static system, leading to the display of erroneous flight data. Article 133 (60-6939) was lost on July 9, 1964, just as Lockheed Test Pilot Bill Park was turning onto final approach into Area 51 having just completed a tri-sonic test flight. The aircraft experienced a complete flight control lock-up and Park was forced to eject at about 200kts as the aircraft continued to increase bank-angle at just 200ft above the desert floor. The cause was loss of hydraulic fluid to the flight control system.

The four hangars and workshops in the foreground were just part of the major redevelopment necessary to support Oxcart flight operations up at Area 51. To enable the A-12 to be tested both at speed and in a secure environment when airborne, the Yuletide Special Rules Area was established above the base; it extended up from 24,000ft to 60,000ft and was approximately the size of England! (Roadrunners Internationale)

On December 28, 1964, Agency pilot Mele Vojvodich taxied out in Article 126 (60-6929) for a Functional Check Flight (FCF), after the aircraft had undergone deep maintenance. With both burners lit and immediately upon rotating the aircraft, it yawed viciously to one side; corrective rudder application caused 126 to pitch-up. It became apparent that all pilot control inputs were having a reverse effect to those intended — in the midst of these uncontrollable divergent effects, Vojvodich was forced to eject from the aircraft not even 100ft above the ground. With just one swing on the open parachute, Vojvodich narrowly missed the flaming pyre of 126, which signified the end of yet another aircraft. The sortie had lasted just six seconds — the shortest of any “Blackbird” flight. A subsequent inquiry established that the SAS had been wired back into the aircraft incorrectly.

On November 20, 1965, the final stage of the validation process was completed when a maximum-endurance flight of six hours and 20 minutes was achieved, during which time an Oxcart demonstrated sustained speeds above Mach 3.2 at altitudes approaching 90,000ft. But the question remained — where to deploy the bird?

Следующий раздел:

TECHNICAL SPECIFICATIONS

Страницы


В нашей электронной онлайн библиотеке вы можете бесплатно и без регистрации прочитать «Lockheed A-12: The CIAs Blackbird and other variants» автора Crickmore Paul на телефоне, андроиде, айфоне, айпаде. Сейчас вы находитесь в разделе „DESIGN AND DEVELOPMENT“ на странице 4. Приятного чтения.