Investigations Concerning Improvements of the SAAB 37 Windshield Birdstrike Resistance,
SAAB-SCANIA A B LINKOEPING (SWEDEN) AEROSPACE DIV
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In 1980 some tests at Holloman AFB indicated that the windshield was less resistance than previously anticipated. Further birdgun tests were therefore started in Sweden. A method for accurate measuring of windshield deflections using high speed cameras was also developed. Beside establishing the protection level given by the serial windshield, the tests also made clear that the windshield might rupture below its undisturbed strength, if the bird impact made it deflect to contact with underlaying equipment. The head-up display was the main but not the only such equipment. Also birdspray entering the cockpit between the deflected windshield and the canopy was a major problem. The study now concentrated on establishing the probabilities of aircraft losses due to birdstrikes. Calculations were performed both regarding overall loss rates and risk levels for individual aircraft versus speed. The calculations specially dealt with the improvements that could be gained by a number of proposed modifications and the safety levels achieved.