SOME FACTORS INFLUENCING SPINAL INJURIES IN SEAT EJECTED PILOTS.
Explore the source record for details and available documents.
SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Explore the source record for details and available documents.
Full coverage anti-G trousers, a chest counter pressure garment for positive pressure breathing for G tolerance, and a smaller ejection seat headbox have been developed for future agile aircraft. The hypotheses that the new headbox might improve, and that the more restrictive high G garments might compromise, pilot head mobility were tested. The RAF institute of Aviation Medicine Hawk aircraft was equipped with a wide angle video camera facing the front seat pilot. Two experimental conditions were compared to the control air combat sortie: 1. standard garments and the smaller headbox; 2. high G garments and the smaller headbox. Data were recorded from five instructor pilots during three scheduled air combat training sorties. Their helmets were marked with 10-mm white dots in a standardized pattern. Software for recording helmet dot positions from single frame video images, and a trigonometric method for calculating head rotation and translation from changes in the helmet dot positions were devised. No differences were found between headboxes or garments at the three extremes of head movements analyzed. Observed neck rotations were similar to maximal seated norms. Optimal head and neck extension is impeded by the ejection seat headbox. Pilots' head movements are not restricted during air combat at moderate G levels.
During the years 1958-91 17 Finnish pilots were forced to use ejection seats. The aircraft types were as follows: a) BA Hawk in 6 instances; b) a Mig 21-F-13 in 4; c) a Mig-21-Bis in 3; d) a Gnat Folland in 2; e) a Vampire Trainer in 1; and f) a MU-3 in 1 case. There were 3 ejections completed successfully, 12 pilots sustained slight injuries, and 5 pilots suffered major injuries--3 from compression fractures of the thoracic spine, 1 from fracture of the femur, and 1 from rupture of the medial collateral ligament of the knee. All major injuries were associated with Soviet aircraft. One BA-Hawk pilot died due to a direct impact against a tree after a low-altitude ejection. Two pilots launched the seat under negative G-forces. One of these became temporarily blind, and suffered a partial loss of vision for 3 months. Four Hawk pilots were saved during landing phase by a tandem ejection, receiving only minor injuries.
It is generally accepted that in the case of ejection, the flexion posture is often the reason for vertebral body fracture, but to maintain the right egress posture (this means an erect or even hyperextended position) throughtout the entire duration of flight would increase pilot complaints about validly criticized misalignment of the seat profile. X-ray controlled seat studies led to the conclusion that an acceptable egress position does not allow relaxed sitting posture during normal cockpit activities over long periods. Therefore, an attempt at solution is being made by a seat device whose comfort is guaranteed by a back-rest construction variable at will. For emergency case, the posture will be optimized automatically and synchronically with the action of the power retraction unit. A schematic design outlines the construction.
To obtain tolerance limit of human upper extremity with arm restraint plate on eject seat to windblast, impact was applied to the upper extremity of 13 human corpses and 7 living monkeys by a spring driven impact device. Relationship between impact load, moment of elbow joints and arm injuries with arm restraint plate were studied. Relationship between biomechanical characteristic curve of human elbow joint and clinical injuries was obtained. The results indicated that tolerance limit of human upper arm is higher than forearm. Safety limit of human anterior arm to simulated aerodynamic load is 1.26 kN.
A mathematical theory is being developed in order to calculate the aerodynamic loading to which a pilot is exposed during high-speed ejections. Neglecting the initial effects of flow separation, results thus far indicate that a pilot's musculoskeletal system is not likely to withstand the tendency for limb-flailing if he is ejecting at Mach numbers in excess of about 0.7. This tendency depends very strongly upon the angle at which the pilot's limbs intercept a high-speed flow; the forces that cause limb dislodgement increase dramatically with speed of ejection. Examining the time-course of limb-dislodging forces after the initial onset of windblast, the theory further predicts the generation of a double vortex street pattern on the downstream side of the limbs of an ejection seat occupant. This results in the corresponding appearance of oscillating forces tending to cause lateral motion (vibration) of the limbs. The amplitude and frequency of these oscillating forces are also very dependent on the Mach number of ejection and the angle at which the pilot's limbs intercept the flow. However, even at moderate Mach numbers, the frequency can be as high as 100 cycles per second, and the amplitude rapidly exceeds a pilot's musculo-skeletal resistive powers for Mach numbers above 0.7.
A review of all aircraft accidents and incidents in the Canadian Forces over the last 20 years (1962-1982) has been carried out. There have been 47 cases of serious loss of cabin pressurization in ejection seat equipped aircraft. Altitudes varied from 15,000 to 54,000 ft (4,572-16,459 m). No one aircraft appears to be more vulnerable. The most common cause was problems with the canopy seal (25%). There were three cases of hypoxia and two cases of decompression sickness. No deaths or permanent injuries occurred. Loss of pressurization is an extremely low, but definite risk to the pilot and aeromedical training with practical demonstration in the hypobaric chamber should continue.
From 1967 to 1987 there were 83 successful and 9 fatal ejections with Saab rocket seats in the Swedish Air Force. Medical consequences and injury factors are reviewed. Thirty-nine survivors had nontrivial injuries; four were seriously injured. The risk for injury has been approximately 50% throughout the period. Two-thirds of the survivors resumed flying within a week, the remainder after up to 1 year, except for three pilots who terminated their flying status.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.