WHEN Anatoly Kvotchur flew his MiG-29 at the 1989 Paris Air Show he planned to show the world what spectacular feats his Soviet fighter could perform. One of the highlights was a slow turn at low altitude, with the aircraft鈥檚 nose pointing upwards at 45 degrees. But as the plane came out of the manoeuvre at a speed of only 180 kilometres per hour, a bird flew into one of the MiG鈥檚 two engines. As the engine lost power it rolled to the right, then plummeted towards the ground. At an altitude of only 150 metres, Kvotchur pulled the ejection handle.
A preprogrammed sequence of events then followed at mind-boggling speed. First, the MiG鈥檚 ejection seat forced Kvotchur鈥檚 body into the position that offered the best chance of survival. Explosive cartridges tightened his harness, pulling his shoulders back and his stomach in. To prevent his arms flailing, paddles at the side of his seat flicked them towards his body. At the same time, his knees were forced upwards where they could protect internal organs. And all this within just 50 milliseconds of Kvotchur pulling the handle.
Next, the MiG鈥檚 canopy shot away from the plane, and a high-pressure gas gun forced Kvotchur鈥檚 seat up a set of guide rails and out of the cockpit. As the seat lifted, leg restraints attached to the floor pulled his legs into position. A second explosive charge detonated when the chair had risen 1 metre from its mountings, propelling it away from the aircraft that was now plummeting towards the ground. As the seat left the cockpit, a pair of telescopic metal booms deployed from the back of the chair, behind Kvotchur鈥檚 shoulders. The end of each boom carried a small parachute that prevented the seat tumbling in midair.
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By now Kvotchur was clear of the aircraft, and an extractor rocket fired out of his seat鈥檚 headrest, pulling the main parachute with it. He was so close to the ground that the parachute did not have time to open fully, despite the rocket extraction. But it did break his fall, and less than half a second after the ejection began, Kvotchur was on the ground, 15 metres from the burning wreckage of his plane. He was conscious, and still strapped into the ejector seat that had saved his life.
Expendable aircrews?
The incident surprised military analysts in the West. Throughout the Cold War, they had believed that ejector seats were a low priority for the Soviet air force because, they thought, the Soviets considered their pilots to be expendable. Kvotchur鈥檚 survival proved otherwise, and two years ago the US Air Force and Navy commissioned the aerospace company Rockwell to find out just how good the Russian seat really is. The Americans learned a great deal from the $6 million evaluation programme, and there are plans to use this knowledge to build better seats, which will allow pilots to eject from a stricken plane at higher speeds and lower altitudes than is possible with existing models.
The most dangerous time for a pilot to have to eject is when a plane is at low altitude, flying fast, and possibly upside down or even rolling out of control. In the 1960s, the US Air Force decided to concentrate its efforts on low-altitude ejections, which it believed were likely to be the most frequent. The result of this decision can be seen in the 鈥渁dvanced concept ejection seat 2鈥� (ACES II), which was introduced in 1978. It has been used in almost 280 ejections, and over 90 per cent of the pilots involved survived. Today the ACES II is fitted to more than 6000 American military aircraft, including the F-15 and F-16 fighters and the B-1 and B-2 bombers.
The US Air Force calls the ACES II a 鈥渮ero-zero鈥� seat, claiming it can save a pilot鈥檚 life if the aircraft is in level flight at zero altitude and at zero speed. McDonnell Douglas, the American aerospace giant that helped design and build the seat, says it has worked out how Kvotchur would have fared had he ejected in an ACES II. 鈥淥ur study showed that his parachute would have opened twenty feet before he hit the ground,鈥� claims Blair McDonald, who heads the project to build the next generation of ejection seats at the company. 鈥淭he Russian seat is primarily a high speed ejection seat,鈥� he adds.
The Russian seats are a product of the Zvezda Design Bureau, the company that is responsible for all flight crew safety and survival equipment in Russia. Zvezda鈥檚 K-36 series of ejector seats is used in most modern Russian military aircraft. The company also fitted the ejector seats in the now abandoned Soviet space shuttle. The seats allow cosmonauts to eject during a launch at speeds of up to Mach 4 and at altitudes of 30 kilometres or more. They are similar to the K-36 seat used by Kvotchur, with extra features such as a second set of stabiliser booms and a solid rocket booster to propel the chair further from the launcher.
Zvezda now markets its seats and expertise abroad and two years ago, Rockwell put the K-36 through its paces, using test facilities at Zvezda鈥檚 headquarters at Tomilino, near Moscow. Wind tunnels there can simulate the force of the wind during an ejection. The testers also fired the seats from rocket-propelled sleds that mimic the g-forces during an escape, and even shot them out of a modified MiG-29 during flight. In each case, seats carried a test dummy wired with instruments to measure the wind blast and g-forces.
The results showed that at high speed the Russian seats far outperform their American counterparts. In ideal conditions, ACES II seats can work at up to 1100 kilometres per hour. But very few pilots have survived ejections at more than 900 kilometres per hour, says James Brinkley, director of crew systems at the Wright-Patterson Air Force Base in Ohio. A realistic safe limit is more like 800 kilometres per hour, and even then the pilot鈥檚 chances are drastically reduced if the aircraft is upside down or spinning out of control. The resulting g-forces generated under these conditions can kill a pilot. Rockwell鈥檚 test showed that in an ejection at 1350 kilometres per hour, a pilot using a K-36 experiences g-forces no greater than those in an ACES Il at 830 kilometres per hour.
Wind cheaters
But g-forces are only part of the problem. If an aircraft is travelling at high speed during an ejection, the force of the wind can break bones and even kill the pilot. So the Zvezda seat has a wind deflector that pops up between the pilot鈥檚 knees, reducing the pressure on the pilot鈥檚 chest by 30 per cent compared with what would be experienced in American seats. Zvezda also manufactures an adjustable version of the K-36 which, unlike ACES II, can accommodate crew members of widely varying sizes, including smaller female aircrew. The US Navy and Air Force were so impressed that earlier this year they set aside a further $400 000 to find out whether the K-36 could be adapted for use in American aircraft.
Engineers are designing a 鈥渃oncept aircraft鈥� as part of the multibillion dollar Joint Advanced Strike Technology Program (JAST) to build a prototype fighter for the Air Force and the Navy. The seat for the JAST will have to meet stiff criteria. It must work at speeds over 1300 kilometres per hour 鈥� a standard that the K-36 already seems to meet. But it must also work at low altitude when the aircraft is spinning out of control. The Air Force and Navy have been testing the K-36 in a $2 million programme at the Holloman Air Force Base in New Mexico, where there is equipment that can simulate low-altitude ejections from crippled aircraft. One worry was that the stabilisation booms on the K-36 might create exceptionally high g-forces as they bring the seat under control. But preliminary results for the tests, which were completed in November, show that the seat performed even better than expected.
Despite these successes, Zvezda is up against strong opposition in the contest to supply the next generation of ejection seats for the US military. McDonnell Douglas is designing its own seat in the $20 million Fourth Generation Seat Technology Program, which is funded by the US Air Force and Navy. Instead of relying on booms and parachutes to stabilise the seat as it punches out of the aircraft, McDonnell Douglas is using rocket motors to control the seat鈥檚 attitude and velocity. During low-altitude ejections like Kvotchur鈥檚, the system should be able to deposit the pilot gently on the ground. Most importantly, it could control the seat even if the plane had begun to roll. The big challenge is to protect the pilot from lethal g-forces, and to do this, the rockets have to be controlled by computer. 鈥淕etting the control algorithm right is a major challenge,鈥� says Jim Schoen, an engineer on the project. 鈥淎 brick has better flying characteristics than an ejection seat.鈥�
Flight capsule
A more ambitious idea is to put the pilot inside a self-contained, enclosed capsule that separates from the plane. The idea is not new. The US Air Force鈥檚 F-111 fighter-bomber, which became operational in the late 1960s, had a single escape module for the pilot and copilot who sat side by side. Inside the capsule the crew were protected from wind blast and the freezing temperatures of the air at high altitudes. The module also served as a life raft if it landed in the sea. Unfortunately, in its original form the capsule ended up being heavier than planned and so descended more quickly after an ejection, often inflicting spinal injuries on the crews. The capsule鈥檚 parachute also took 11 seconds to open, making very low-altitude ejections particularly dangerous. The capsule has since been modified but still has limitations compared to open seats.
McDonnell Douglas and Boeing are building on this idea in a multimillion dollar project to develop a new generation of escape capsules. The project is called the Advanced Technology Crew Station Program and is being funded by The Naval Air Warfare Center in Warminster, Pennsylvania. The capsules they are developing are a far cry from the 1960s version. In future, the entire cockpit could separate from the plane and be flown to safety like a small aircraft. Instead of being built out of metal, the capsules could be built from strong, light carbon-based materials such as Kevlar. Flat panel displays could take the place of the bulky cathode ray tubes to display information. The explosive cartridges that launch the capsule may be triggered by lasers, which are more reliable than the high-pressure gas lines used in today鈥檚 seats and would do away with the plumbing that is now needed. And a pilot housed in an escape capsule would be able to lie right back, making high g-forces in fast turns easier to withstand. In today鈥檚 aircraft, such as the F-16, the escape system limits this angle to 30 degrees. The pilot may even view the outside world indirectly, through images projected onto a wraparound display, but cocooned inside the capsule would not have to wear an exposure suit.
Life-saving developments can be quite simple, too. Later this month, McDonnell Douglas is due to start testing a helmet that reduces the forces on a pilot鈥檚 head and neck during high-speed ejections. The problem with conventional helmets is that the dome shape acts like the surface of a wing, creating lift as air passes over it. During ejections at more than twice the speed of sound it can create enough force to break a pilot鈥檚 neck. McDonnell Douglas has devised a brim over the helmet that redirects the airflow to reduce lift. The tests will determine exactly what shape this brim should be.
Meanwhile, the US military is spending millions of dollars on developing high-tech equipment to safeguard aircrew who have to bale out of their planes. If all goes to plan, the next generation of seats 鈥� whether Russian or American in origin 鈥� could be in service by the end of the century, helping the crew of doomed aircraft to survive. The designers of the new systems have a tough target to meet: they have to better the 90 per cent success rate of ACES II.
