Antigravity; Flight Tests; Gravitational Fields; Jas-39 Aircraft; Oxygen; Pressure Suits

Flight Test and Development of a New Anti-G System in JAS 39 Gripen

Berglund, Christer; Marklund, Bjorn; Oct 2005; 17 pp.; In English Report No.(s): AD-A446431; No Copyright; ONLINE: http://hdl.handle.net/100.2/ADA446431; Avail.: CASI: A03, Hardcopy

A new oxygen and anti-g system has been implemented in the Swedish forth generation mulitrole aircraft JAS 39 GRIPEN C and D. In the Gripen the pilot is exposed to 9G for long periods of time. Therefore the Anti-G protection is more important than ever. Due to the implementation of OBOGS (On Board Oxygen Generating System), the anti-g system also had to be changed. During the first test flight with high G-loads with the new OBOGS and anti-G system in GRIPEN test aircraft 39-800 (twin-seat) the pilots got a grey-out and after evaluation of data from the flight it was shown that the pressure in the G-suit was below specified limits. At this time it was suspected to be an individual problem with the G-regulators and therefore they were changed to other units, but due to flight tests of the ECS (Environmental Control System) another problem arose before the anti-G testing could go on.

The ECS tests showed that the supply pressure from the ECS during some flight cases was below the minimum requirement that the OBOGS and anti-g system was qualified for. The anti-G tests had to be postponed until the supply pressure to the anti-G system could be guaranteed to be above the minimum requirements. Therefore a number of changes to improve the supply pressure and reduce the pressure drops in the anti-g system were implemented. After a new test period with testing of the modifications, which were successful, the problem with the low pressure in the g-suit still existed even though the G-regulators had been changed.

After tests of several G-regulators it was shown that a high percentage of the G-regulators gave a low pressure in the G-suit and quite often below minimum specified values. After some close teamwork with the G-regulator supplier HAY, a modification of the anti-gregulator was made in order to be able to guarantee correct pressure in the g-suit. DTIC

Antigravity; Flight Tests; Gravitational Fields; Jas-39 Aircraft; Oxygen; Pressure Suits

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