Soviet UAV Lavochkin La-17

Soviet developments in unmanned aircraft lagged behind those occurring in America, the United Kingdom and Germany. The upheavals after the revolution and the intensity of Russian involvement in the Second World War had left their mark on the Soviet research and development base. When the very existence of a country is at stake, any programme that does not directly contribute to the main war effort is a distraction.

Once the war was over resources could be diverted to new projects. Initially advances in jet fighter technologies preoccupied the main aircraft design bureaus. New research facilities were also created to help develop transport aircraft and helicopters. Many of the names that remain famous today, such as Antonov and Kamov, saw their genesis during this period. Such was the need to play catch-up with developments in the west that there was not a great deal of funds left for the development of unmanned aircraft. Rapid developments in missile technology, however, did create conditions where target drones would need to be developed.

Being ever pragmatic in their approach to the development of new capabilities, the Soviets initially sourced their need for target drones by adapting former manned aircraft into their new role. Aircraft such as the MiG- 15 had an additional letter M added to their designation to indicate they were a mishen (target). The early variants were manually flown into a test area before the pilot handed over control of the aircraft to a ground station and ejected. If the target drone was to survive the engagement it would be destroyed by remote control from the ground. This approach, however, was not sustainable and the requirement for a low-cost target drone was developed. The first variant of this was the La-17 (Izdeliye 201) which emerged from the Lavochkin design bureau.

The La-17 design was quite simplistic. It was designed to be launched from a large bomber acting as a ‘mother ship’. The aircraft first selected to act in this role was the Tupolev Tu-2. It had been mass-produced in the Second World War and was therefore available in large numbers. However, mating the La-17 to the Tu-2 proved problematic. The plan to fly the La-17 from the Tu-2 was quickly abandoned in favour of attaching it to the Tupolev Tu-4 heavy bomber, a derivative of the Boeing B-29.

The design of the La-17 involved a series of compromises. Weight requirements ruled out any means by which the UMA could be recovered if it failed to be destroyed by a fighter in the course of an engagement. The La- 17 could therefore fly for a maximum of forty minutes before it would belly-flop onto the ground and onto the engine. Despite this somewhat simplistic approach, photographs show La-17s with several markings on their tails indicating that they have been used more than once.

In the first flight tests a problem with engine thrust became apparent. The top speed of the Tu-4 was insufficient to prevent the La-17 diving after it had been released. The RO-900 engine simply could not generate enough lift at this speed as the air flow into the engine chamber was insufficient. Ramjet engines are simply unable to move on the ground without external power. They rely on forward motion to compress air into the combustion chamber and work most efficiently at speeds around Mach 3.

Once the La-17 had been dropped from the Tu-4, control often took around ninety seconds to be established. At a speed of around 850 kilometres per hour (528 mph) the La-17 was able to make the kind of manoeuvres required to make the task of shooting it down representative of a current threat. These problems caused the programme to be suspended for a short period of time while modifications were made. After successful flight tests by ten La-17 drones in a variety of roles it entered service with the Soviet Air Force where in various advanced configurations it would remain in service for nearly thirty years.

In contrast to the pulse-jet engine flown on the V-I, the design team opted for a ramjet. This was a far from ideal choice. Fuel consumption rates limited the length of time the La-17 could fly. This gave it a higher overall speed of 900 kilometres per hour (560 mph) and an operating ceiling of 10,000 metres (32,810 feet). This configuration of the target drone allowed it to partially mimic the performance of the MiG-17.

The MiG-17s maximum speed was slightly higher at 1,145 kilometres per hour (710 mph) but its service ceiling was much higher at 16,600 metres (54,450 feet). The ramjet configuration was a sensible compromise that meant the cost of the La-17 could be held down. However, with the introduction of the Soviet Union’s first supersonic jet, the MiG-19, into service, the performance of the La-17 soon fell well below that of the fighter jet it was supposed to be simulating. This was not the only problem.

The size of the drone itself posed a problem for contemporary Russian radar system technologies. Its radar cross-section was quite small and needed to be enhanced so the ground-based radar systems could guide the chasing aircraft to a point where they gained visual contact with the target. To enhance the radar signature the target drone could be fitted with a number of Luneburg lenses on the wings and tailplane. These devices increased the radar cross-section of the La-17 by an order of magnitude, allowing it to simulate contemporary threats from the English Electric Canberra or American medium-range bombers such as the B-47 Stratojet.

Despite achieving its initial design goals, other issues were emerging that led the design team to look at developing a new generation of target drone. This was to become the La-17M (lzdeliye 203). It was to be ground-launched from a platform based on a KS-19 anti-aircraft gun mount. This would allow the La-17 to overcome the restrictions of being launched from the Tu-4 which also limited the numbers that could be fired in a salvo. Film taken at the time shows several examples of La-17s being fired in a salvo to create a high-density threat environment. It also had a new radio system and autopilot installed. However, the target drone was hampered by its short range and primitive guidance system.

To launch the La-17M two additional PRD-98 solid-fuel Rocket-Assisted Take-Off (RATO) engines were mounted on either side of the main engine. These had a bum time of between 1.6 and 3.1 seconds. Combined with the main engine running at idle, this generated enough thrust to accelerate the La-17M to more than 300 kilometres per hour (186 mph). Two seconds after launch the main engine was commanded to full power. The boosters were jettisoned after five seconds, at which point the La-17M transitioned to level flight.

After some debate in the design team over the exact configuration of the power plant, a decision was made to use the Mikulin RD-9BK turbojet engine used in the MiG-19. It could produce 19.1 kN (4,300 pounds) of thrust. This was to double the power that was available, although it actually marginally reduced the maximum speed that the target drone could achieve. However, its service ceiling increased dramatically and its flight time increased from forty to sixty minutes.

It was at around this time that rapid developments in missile technologies started to create an increasingly hostile environment for manned aircraft. The ultimate demonstration of this was the shooting down of the U-2 carrying Gary Powers on a reconnaissance mission in Soviet airspace in 1960. Reconnaissance, however, was not a military capability that could be easily given up. The La-17 provided a platform from which a new generation of UMA could be developed that could fly hazardous reconnaissance missions. Yet it was far from being an ideal baseline from which to work.

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