There are some 60 000 parts in a Gripen. Of them about 40 CPUs (likely to become fewer and more powerful in the future).
56% of the structure is made of aluminium alloys. 26% is made of composites, including the fin, wing, canards, most control surfaces and many covers and doors. The wings are made of up to 146 composite layers.
Static destructive load testing was made using 33 of the most critical loadings of the 400 representative cases envisioned. Everything was OK at 150%, at "over 200%" the first crack appeared, in the fin. Another fuselage was tested for fatigue life for at least five years. As part of this programme, parts are deliberatly damaged, and subjected to maximum loads, to see what happens with them.
All Gripens have five sensors to monitor loading forces, this to help judging the need for maintenance of the aircraft and to gain knowledge for the future. One of the main areas of interest is the joining of different materials.
The sensor at the centre of gravity will measure total G-loads, the one at the fin joint and forward wing spar bending moments, at the aft wing spar total load and at the canard bending and twisting forces.
The canopy is made of acrylic and is 9 mm thick. Along the edges and the top centreline is a miniature detonation cord embedded, which shatters the canopy in case of ejection.
The front windshield is 26.5 mm thick and is designed to withstand a 1 kg bird collision at 1000 km/h. In case it deforms on impact the bird remains are directed down and away from the pilot's head by a deflector on the canopy frame.
There's 30797 m of cabling in the aircraft, connecting a bit more than 450 different electrical and electronic units.
(Back to) more on JAS 39 Gripen.
Document created 2000 Sep 20
by Urban Fredriksson