There are some areas where Russia is miles ahead of other nations. In the sphere of aviation, there are quite a few of them. For instance, Russia makes the world's best ejection seats for combat aircraft, the seats providing safer ejection in a wider flight envelope than their Western analogues. This remarkable achievement is all due to Zvezda scientific industrial enterprise headed by professor Gai Severin, who gave an interview to AeroWorldNet on the eve of the Paris'99 air show. He said that several new Russain combat aircraft that are going to be on display at Le Bourget feature new Zvezda ejection seats belonging to the "3.5-series". These are tailor-made versions of the basic model, the K36D3.5.
In its turn, the K-36D3.5 was developed on the base of the older K36DM. The development of the latter began in the middle of 1960s. In 1969 the basic K36 successfully passed state acceptance trials and entered mass production. Since then about twelve thousand K36-series seats have been built in 15 major modifications. These are found in all major types of Russian fighters, including the Su-27 and MiG-29.
Despite its long service life, the K36DM still remains one of the best seats available anywhere. The main advantage of the K36DM over the much younger Martin-Baker Mk.16A (in use on the Eurofighter EF-2000 Typhoon) is that the former provides safe ejection up to the indicator speed of 810 kts in comparison with merely 600 kts for the US-made seat.
This advantage has historic origins. In 1960s the Soviet air force was seriously concerned with the poor safety record of in-service ejection seats. At that time such high-speed airplanes as the Mach 3 MiG-25 interceptor were under development, and the Air Force was looking for radical measures to improve the safety of pilots who would fly the new supersonic aircraft. The Air Force wanted to have an ejection seat that would not only be an effective means of saving pilots' lives, but would also be able to minimise harm to the flight crews in the case of ejection from most unfavourable situations, including take-off and landing operations, flights at low height and at high altitude and supersonic regimes. While the Soviet Air Force postulated demanding requirements for the ejection seats, the US Air Force for some reasons did not do likewise. This determined the Russian advantage in ejection seat technologies.
An important step forward in ejection seat technologies came with development of a special version of the K36 for the Yakovlev Yak-38 deck fighter with vertical take-off and landing capability. This version had an analogue computing unit, receiving information on speed, pitch and bank angles from the flight data system of the aircraft. When flight parameters were too dangerous for continued flight, the computing unit generated a command for ejection. This fully automatic system worked well on the Yak-38, having saved a few pilots of the Russian Navy.
The success of the Yak-38 seat encouraged Zvezda team to develop a new generation of ejection seats which would differ from the old models in having a built-in digital computer to control ejection procedure. The work on the basic seat - the K36D3.5 - began some six years ago. According to Severin, Zvezda's main goal was to provide better working conditions for military pilots, safer ejection and minimal harm to pilots during emergency evacuation from crippled aircraft. By the end of May state acceptance trials on the K36D3.5 are 70% complete.
The K36D3.5 features a multi-program digital system for controlling seat trajectory. The built-in computer is connected to the aircraft onboard data system, from where it gets such parameters as speed, altitude, pitch, bank, alpha, yaw, angular speeds etc. At the moment of ejection, the computer analyses the current flight parameters and generates an optimal ejection procedure. Its memory stores 120 basic algorithms for a variety of possible situations.
When ejection is made from an aircraft flying at a high bank angle, the computer chooses a program providing active controlling for the seat trajectory in the vertical plane. After the seat has parted with the aircraft, a side-force engine is ignited to reduce the bank angle, and then an opposite engine becomes active to eliminate the angular speed. Next to come into action is the lift engine, which brings the seat into a height sufficient for safe deployment of the parachute. In the case of ejection from the aircraft flying upside down, the engines will not be activated. Instead, the parachute will be deployed immediately after the seat departs the cockpit, so as to considerably decrease the minimal safe ejection height.
Although the K36D3.5 represents a revolutionary step in the development of ejection seats, it makes use of a few successful elements of the K36DM that proved highly reliable in service, including the stabilisation system, hand and foot protection mechanisms and flow deflector. At the same time, other elements have been redesigned in an effort to reduce weight. The resulting seat is 25 kg lighter than its predecessor, with a simultaneous reduction in overall dimensions by 15-20 mm.
The new ejection seat offers the pilot more comfortable working conditions than its predecessors. To make the pilot feel better under high g loads during combat maneuvers, the seat has an increased support area. The visibility in the upper sector of the rear hemisphere is improved by decreasing the dimensions of the headrest. Being the most compact in its class, the K36D3.5 offers the widest range of alignment to pilot's stature. In accordance with the latest international requirements, it can accommodate a small woman weighing merely 44 kg and a huge man weighing 111 kg.
The leading Russian aircraft manufacturers have already chosen the K-36D3.5 for installation on their new designs, including the Sukhoi Su-30MK, Yakovlev Yak-130 and Mikoyan MiG AT. The modular principle of the basic seat design allows for easy creation of tailor-made seats to meet specific requirements of aircraft manufacturers and their clients. While Sukhoi opted for the basic version of the seat, Mikoyan ordered a special version without the built-in computer and other expensive paraphernalia. The K93 on the MiG AT weighed merely 185 lb, being the lightest seat in its class.
Severin says that during the work on the K36D3.5, Zvezda engineers paid much attention to the international market. According to him, the K36DM was often commented by Western aircraft manufacturers as "great in performance, but too big and heavy". In reply to the critics, Zvezda created the new seat with overall weight similar to that of in-service Western seats with much poorer performance. In fact, the K36D3.5 fits well into any cockpit of all existing Western fighters, to where it can be installed on request of would-be foreign clients.
