Convair RB-36 / GRB-36D PeacemakerOne of the essential criteria of the early jet powered reconnaissance aircraft was the ability to cruise above 40,000 feet, a level determined by knowledge of the capability of Russian air defence radar’s. The main Russian air defence radar in the 1950’s was the American supplied SCR-270, or locally made copies, which were only effective up to 40,000 feet – in theory an aircraft cruising above this level would remain undetected. The first aircraft, which put this theory to the test, was the Convairr RB-36D, a massive aircraft with 6 piston ‘pusher’ engines and 4 small turbojets, which gave the ‘aluminium overcast’ an operational ceiling of 50,000 feet with no less than 14 cameras. Later a lightweight version of this aircraft, the RB-36-III, could even reach 58,000ft.
In 1951 RB-36D’s, with a range of 9,300 miles, began probing the boundaries of the Soviet Arctic and were rather disturbed to find their onboard equipment indicating that they had been detected by Soviet radar – so much for the theory. However, detecting aircraft on ground-based radar was one thing, intercepting them was far more difficult. A number of overflights of Soviet bases in the arctic, particularly the new nuclear weapons test complex at Novaya Zemlya, were made by RB-36 aircraft operating from Sculthorpe.
Like all early jet fighters, the MIG-15 was essentially a ‘day’ fighter and carried no radar, making interceptions in anything other than good weather very difficult, furthermore, the MIG-15 also lacked the necessary operational ceiling and range to effectively intercept the RB-36D. In fact the Soviet Air Defence Command lacked an all-weather fighter, equipped with a search radar, until the Yak-25 Flashlight entered service in 1956.
Another option considered for the B-36 was as ‘carriers’ for smaller, faster reconnaissance aircraft, such as the RF-84F Thunderflash, which were termed ‘parasites’. In 1952 after a series of trials under Project FICON (Fighter Conveyer) ten B-36D’s were converted to carrier aircraft and given the designation GRB-36D – these aircraft retained their cameras but, apart from the tail gun, all other defensive and ECM equipment was removed. Twenty-five RF-84F aircraft were converted to parasites and given the designation RF-84K – these aircraft were equipped with 5 cameras and still carried four 0.5 machineguns.