Flying computer readied for takeoff

By Leon Engelbrecht, ITWeb senior writer

Johannesburg, 21 Jan 2008

SA's first new jet fighter in over 30 years is a coat of paint away from delivery to the nation's air force. Saab JAS39D Gripen "SA 01" is the first of 28 aircraft, costing R20 billion, according to the National Treasury.

The Gripen (Griffon in English) is a hi-tech platform, more computer than aircraft. Saab flight test operations manager and test pilot Magnus Olsson says the fighter is fitted with 40 Pentium-type processors to control its cockpit avionics, weapons and flight surfaces through a systems architecture called "fly-by-wire".

This last requirement is the result of a deliberate decision to design the aircraft as inherently longitudinally unstable, a parameter that boosts agility and performance.

Since SA 01 is also a test bed aircraft and is fitted with a further two processors to collect data from the many sensors embedded in the aircraft.

SA Gripen test pilot "Blokkies" Joubert says the consequence of so much processing power is that the Gripen is "the easiest aircraft I've ever flown. It is simple and intuitive."

SA 01 made its maiden flight in Sweden in November 2005 and after 25 hours of flight was shipped to Cape Town where it arrived by sea in July 2006 for a 14-month test programme at the SA Air Force's Test Flight and Development Centre, near Cape Agulhas, in the Western Cape Overberg.

Olsson says SA 01 has now completed that programme, clocking up 199 sorties and 178 flying hours. Particular attention was given to the aircraft's software that went through seven major upgrades during the 14-month programme. "We found a lot to fix," says Olsson, "there were a few snags in a few lines [of code]. I think the programme was very good. On the other hand, we found some things could not have been better."

In the cockpit

The test pilot adds the programme robustly tested the hardware and software running the flight control system, the radar, weapons, the helmet mounted man-machine interface, the electronic warfare suite and the aircraft's communications system, which comprises traditional radios and an encrypted wireless datalink.

The cockpit hardware tested includes a wide-angle head-up display and three full colour LCD screens, served by five MILSTD 1553B data busses and the datalink. The tactical information datalink system (TILDS) provides the fighter four high-bandwidth two-way datalinks with a range of about 500km and a high resistance to jamming.

The link works equally well on the ground as in the air, meaning a pilot on standby can attain a high degree of "situational awareness" before take off. It also allows a Gripen to receive or transmit targeting data to another, to an airborne or ground-based command centre, or to other aircraft types fitted with the TILDS.

The system also allows aircraft to use their radars to triangulate a target track, or one aircraft to jam a target while others track, engage or sneak up on it. They can also pool their radars to "burn" through enemy jamming. In reconnaissance mode, Gripens can transmit gathered data in real-time for interpretation and use.

The test programme was run from the Gripen Flight Test Centre (GFTC), at Overberg air force base. The centre is a scaled down version of Saab's main facility in Linkoping, Sweden, and is based on the SecureNet concept using commercial IT - including HP and Sun processors. The GFTC - which will this year be handed over to SA - is dimensioned for 20 simultaneous users.