Flight-RefuElEd IVIiG-15 bis

The limited range of first – and second-generation jet fighters posed nightmarish problems for their operators. The first turbojets were quite thirsty, and auxiliary tanks of various types and sizes did not provide the long “legs" that the aircraft’s mission demanded. In-flight refueling was the best answer because it increased the range in direct proportion to the amount of fuel transferred.

To study the feasibility and capabilities of such a system, three pro­duction MiG-15 bis’s were modified; in total, five aircraft were involved in the development process. The equipment required at both ends of

such an operation was developed by the Yakovlev ОКБ. The refueling process unfolded this way. From the wing tips of the tanker aircraft (in this case a Tu-4 bomber) flexible hoses were released. At the end of each hose was a funnel-shaped device called a drogue. The MiG-15s were fitted with a probe in the left upper nose of the fuselage. To refu­el, the fighter pulled up to one of the drogues. Once the connection between the probe and the drogue was secure and the ball joint locked in place, the refueling operator aboard the Tu-4 activated a motor – pump that sent fuel down the hose to the fighter. The tanker could refuel two fighters simultaneously.

The first test flights helped to clear up three important points:

1. New homing equipment was needed to simplify the rendezvous of the tanker and the fighters in midair

2. Pumps with faster delivery rates would have to be developed in order to shorten the refueling process as much as possible

3. Very precise rules were required to govern the movements of both tankers and fighters during the refueling process

As the tests continued, several unfortunate phenomena came to light and complicated the procedure. Immediately after the fighter broke the link with the drogue, for instance, the fuel that remained in the tanker’s hose spilled into the fighter’s engine air intake or over its

canopy. The engine did not flame out because the VK-1 was far better in terms of combustion stability than its predecessors; but kerosene vapors did enter the cockpit via the pressurization conduit, and the pilot had no choice but to inhale them until the next air-conditioning blowout cycle. This situation was remedied by fitting the drogue with an electromagnetic shutoff valve controlled by the tanker’s refueling operator.

The MiG-15 bis in-flight refueling tests were never completed, since the coupling process required very highly trained pilots. The two men in charge of those tests conducted in 1953 were two LI I pilots, S. A. Anokhin and V. Pronyakin.