FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1986
1986 - 0400.PDF
Saab unveils refined Gripen Above Gripen's revised outline. Below The engineering mockup LINKOPING Saab-Scania has shown the definitive shape of the JAS.39 Gripen multirole combat aircraft for the first time, reports Mike Gaines. Inspection of the full-scale wooden engineering mockup reveals that the most striking change from previously released drawings and model photographs is Gripen's fin. The thin fin has been replaced by a broader-chord and thicker fin bearing a distinct family resemblance to that of Gripen's predecessor, the Viggen. Tommy Ivarsson, vice-president of Saab- Scania's Military Aircraft Sector, says that the original fin was of too thin a cross- section for the easy installa tion of such items as the rudder hydraulics and servos. The thicker fin easily accom modates them and, on the mockup, includes a location for a radar warning receiver. Gripen has three roles: lighter, attack, and recon naissance and, according to Harold Schroder, senior vice- president of Saab-Scania's aircraft division, "will be truly multirole". Each Gripen will always carry all the hardware and software for each role. "All you need to change is what is on the pylons. The Viggen was multirole, but only with three distinct models. We broke the trend towards higher cost in succes sive generations by aiming for a smaller aircraft with corre spondingly less volume and weight, therefore less prod uction costs, and therefore more aircraft for the amount of money available. "But the aircraft is equally useful in all three missions. All the pilot does is select which mission he wants from the software programes, which will all be carried permanently. It is a tactical boon also. One mission you can have, say, half your force in the fighter role and the rest in attack. The next mission all attack, the next all fighter or all reconnaissance. You can change your complete order of battle. For a potential enemy that makes life very difficult," says Schroder. The four partners of the JAS Industry Group—Saab- Scania, Volvo Flygmotor, w L. M. Ericsson, and FFV— signed a fixed-price contract with the Swedish Air Force for the 30 production Gripens, with an option on a further 110 aircraft. Eventually some 340 Viggens will need replacing. The SAF has no requirement for a two-seat Gripen, but Saab has plans in hand should the service decide next year to buy two- seaters. "We decided to continue with planning a two-seater so that it would be available should the Air Force want it. We would put in a half-metre fuselage plug and move the cockpit forward by that amount. All the weapon systems would be retained. At present the Air Force intends to use experienced Viggen pilots to crew the first 30, but after that there will be younger, pilots coming along. You don't need the two-seater to teach them how to take-off and land it. It should be rela tively undemanding. But teaching them how to use Gripen in three roles could be demanding without a two- seater. And, of course, there are some missions where a two-seater could be useful. If the Air Force wants it, and they will decide next year, then we will be able to produce it quicker because of the design work we have done now," says Ivarsson. Building and testing of the initial Gripen major sub assemblies is progressing on schedule towards a first flight date sometime next year. Saab will not give the exact date, but Flight understands that it will be too late for Gripen to fly at Paris. "We have built two forward fuselage/cockpit sections, and have used these for birdstrike tests. Next they will be used for ejection-seat testing, and then for lightning strikes. We have also produced the fuselage/wing attachment section and the fuselage-gun section. A complete fuel system is undergoing tests in a total-freedom tilt rig, and we have got the fly-by-wire system 'flying' the hydraulics rig from the cockpit simu lator. That is rather elaborate, but we've learned a lot. At present we are bringing the hydraulics up to flight stan dard," says Ivarsson. Volvo Flygmotor has now completed l,400hr of bench testing on the RM12 engine, which is a General Electric F404 modified to meet Swed ish requirements. The front end is beefed up to withstand birdstrikes better, and thrust is up by 10 per cent on the F404. By 1990 the Growth II RM12 will have achieved a 20 per cent thrust increase, and Growth III will see a 30 per cent increase by 1995. Ericsson's JAS radar is also on schedule, says the com pany. The multimode pulse- Doppler set being worked on in conjunction with Ferranti uses some of the technology developed by the latter for Blue Vixen, which is to be fitted to the Royal Navy's Sea Harrier. But Gripen's radar will use an all composite- construction flat plate antenna. Ericsson is also simulator-running a first- generation JAS system com puter of 1 megabyte primary memory. The system has been debugged, and Ericsson is now working on making it half the present size in time for the first flight next year. Software is presently written in Pascal 80, and Ericsson is working to make the programme Aida compatible. Any problems with Gripen? Tommy Ivarsson: "Well, the weight is still slightly over what it should be, but every day we find ways of trimming it back. It will be in spec, because it has to be." Can't Saab use aluminium-lithium alloys for the metal parts of Gripen, which is 30 per cent composite construction? "I wish we could. That would solve the problem overnight and give us plenty in hand. But the fact is that there is no aluminium-lithium available. Not in sufficient flight-proven quantities. It's around, but, as I say, it's not been approved for flying yet". FLIGHT INTERNATIONAL, 22 February 1986
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
