Warplanes: Ejection Dysfunction

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September 25, 2010: The U.S. F-35C (the vertical take-off version, or STOL, for Short Take Off And Landing) is having ejection seat problems. The need to get a pilot safely out while the aircraft is at low altitudes, and possibly at an odd angle, has created difficulties. A related problem is designing the ejection seat so it can handle a wide variety (in terms of weight) of pilots. Because women can operate the F-35, the ejection seat has to safely handle people weighing from 47-112 kg (103-245 pounds). Then there is the problem of getting the canopy out of the way. For stealth purposes, the F-35 canopy is particularly hefty, making it more difficult to quickly get it removed before ejection. Then there are problems with preventing pilots from losing an arm during a bailout. One of the two ejection seat suppliers has designed a special web device that restrains the pilots arms during ejection.

The other solution is a custom flight suit. The “JSF light-weight coverall” is similar to the standard flight suit, worn by all air force pilots, except that it has provision for a removable fabric cord on the upper sleeve. These cords are only worn when the pilot is seated in the ejection seat, and attach to the centerline harness buckle on the ejection seat. The “JSF light-weight coverall” also removes a small pocket from the left leg of the flight suit. When the pilot pulls the ejection seat handle (between his legs), the cords keep his arms close to the centerline of the ejection seat. The ejection seat is rocket propelled, and leaves the cockpit at high speed, and the design of the F-35 cockpit creates the possibility that the pilots arms could be injured (by debris or parts of the cockpit) if they were not kept together during ejection. This is considered more of a problem in the F-35 than in other aircraft.

Ejection seats costs between $200,00-300,000. Most ejection seats weigh about half a ton, and are complex bits of technology. Ejection seats became essential as military aircraft became so fast, that a pilot could not safely climb out of the cockpit and jump. With the higher speed, there was the danger of hitting the tail. Also, escaping pilots were often injured or stunned, and unable to get out quickly enough.

The first ejection seat design was developed in Germany, where the seats were first installed in their He 219 night fighters, in 1943. These used compressed air to propel the seat out of the aircraft. A year later, rocket propelled seats were installed in the He-162 jet fighter. By the end of the war, all of Germany's jets were equipped with rocket propelled ejection seats. While the Swedish firm SAAB had also developed a rocket propelled ejection seat, it was British firm Martin-Baker that jumped in after World War II and created a design that quickly filled the needs of most Western air forces.

The U.S. Air Force long insisted on using only American made ejection systems, but the U.S. Navy stayed with Martin-Baker, because the American ejection seat did not function as well at very low altitudes (where a lot of naval aviators have to eject during carrier operations). Martin-Baker supplies about two-thirds of the ejection seats for Western fighter aircraft. The only American manufacturer, Goodrich, has apparently lost out to Martin-Baker in the competition to supply F-35 ejection seats. But Goodrich is suing to halt the contract going to Martin-Baker, on several litigatable grounds. The other major supplier of ejection seats was the Soviet Union. Those manufacturers continue to produce good ejection seats for Russian aircraft. Over 10,000 aircrew have successfully used ejection seats since World War II.

 

 

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