FLIGHT TESTING THE GRIPEN - MORE THAN JUST AN AIRCRAFT!
In relatively quite isolation Sweden, with a population of less than nine million, has produced a weapons system that rivals the best in the world. It has been described as a 4th Generation weapons system, which in their own words means that it has all the onboard systems talking to each other via a digital infrastructure, that pilot effectiveness and situational awareness have been maximized (requiring a data-link capability), that the aircraft exhibits carefree handling and performance, and that the aircraft has a multi-role (ability to change roles on the ground) or swing-role (ability to change roles in the air) capability to increase the operational effectiveness of each aircraft - if you then combine this with a very good support capability, which is mobile and has layers of redundancy you have a 4th Generation weapons system. The Swedish Aerospace industry set out to create this total package with the Gripen system.
The concept that is central to the design philosophy of the Gripen system is 'information superiority'. As an ex-military fast-jet pilot I understand the term 'air superiority' and as a computer user I understand 'information technology'. I further understand that 'real-time' information during a conflict is vitally important. However, I had never come across the term 'information superiority' (the combination of all three terms) as the central theme behind a fighter aircraft weapon system. From the beginning the Gripen was designed with 'information superiority' being the driving force, not necessarily aircraft performance as with most manufacturers. That's not to say that the Gripen aircraft does not have excellent agility and performance. So what do you get for your money when you buy a Gripen weapons system? You get a 4th Generation aircraft, data-link transfer of information (in to and out of the cockpit), a highly automated cockpit (particularly weapon and radar modes), mobile command and control systems, fighter control data-link capability, enhanced training systems, simplified logistic support and much more.
Because of advances in technology and the need for defence budgetary constraint in the military environment of today, the Gripen system was designed as multi-role/swing-role from the start. This in-built flexibility enables one aircraft to cover the Air-to-Air, Air-to-Ground, Air-to-Sea and Reconnaissance roles. However, this would have meant workload saturation for the pilot in a 3rd Generation aircraft. Moreover, the need to dramatically reduce the pilot's workload has dictated that on-board systems must not only be easy, and intuitive, to use but that they must help the pilot with the decision making process. It was with these objectives that the Gripen's cockpit was born. Without the ties of the major aerospace manufacturers, the Swedish aerospace industry has developed aircraft that are subtly different - with simplicity being the main driver.
As part of an extended visit to the F7 Air Force Base, near Såtenäs in Sweden, I had the chance to flight test the whole Gripen system and to learn some of the design background that has made it what it is today - a truly multi-role/swing-role capability, probably the first of its type in operational service.
BASIC CONCEPT (back to top)
The basic concept behind the Gripen weapon system was to have a versatile and fully integrated weapons system that made the job of the pilot as easy as possible. The key features include: real-time (or near real-time) transfer of military data between aircraft elements and command and control centres, modern agile aircraft that are as simple to operate and fight as possible, a high standard of capability in all aircraft combat roles, the ability to reconfigure the aircraft and support systems to the changing political demands, total mobility, numerous layers to the command and control structure to give redundancy, and if possible the aircraft must look good! To maximize all this potential a good training capability is also required. The Swedish view on training is not to train anything in the air if it can be taught on the ground. This mentality has caused them to produce a very comprehensive training suite, comprising computer based training aids, Multi Mission trainers and Full Mission Simulators - all of which can be linked together to give a realistic 'package' training capability. Soon the two-seater Gripen will be arriving on the training squadron to further improve the training capability.
'INFORMATION SUPERIORITY' (back to top)
One part of my visit that I did not foresee was the Gripen's information transfer capability. I had expected a modern fighter, fly-by-wire aircraft to handle well, I had expected good performance, I even expected highly sophisticated planning and training aids, but I had never seen the likes of their Tactical Information Data-link System.
The Swedish Air Force have been using data-link technology in their aircraft since 1986, when it was used in the Vigen. They are probably the most experienced and developed air force in the world when it comes to using this technology. The basic principle sounds simple: transfer military information to the cockpit and out of the cockpit to wherever it is needed in the combat environment. The implementation of such as system is not as simple. Indeed, aircraft such as the Super Hornet and Typhoon will be the first aircraft outside Sweden to have a capability that comes anywhere near that of the Gripen. Other aircraft in service today (Tornado F3, etc) have some interesting and quite good capabilities, particularly with the Joint Tactical Information Display System (JTIDS), but the Gripen's data-link system really was the 'next' generation.
In Cockpit Information (back to top)
In the cockpit the information that is data-linked to the aircraft is displayed on the centre multi-purpose display (MPD). This display is the tactical display, showing a 'gods-eye' view of the world with your aircraft towards the bottom centre of the display (similar to JTIDS). This display can show the navigational waypoints, targets, ground map and so on. The data-linked information that can be received from other sources includes the position of targets (both airborne and on the ground), waypoints, weapon data and other tactical information. The data are transmitted from a fighter controller on the ground or from another airborne aircraft. The airborne aircraft can either be another Gripen or an early warning aircraft. Information about the state of the systems of other aircraft in the formation is also displayed on the screen. For example, how much fuel each aircraft has, how many weapons are left and indeed what types of weapons are left. All this information is displayed in a simple to assimilate way, giving an incredible increase in situational awareness. With the Gripen you constantly know the 'state' of the other members of your formation. It was also possible to 'lock' your radar on to your wingman, then with a press of a button you could synchronize all the position data between the aircraft. This meant that for co-ordination purposes both computers were using exactly the same navigational positions.
During deployment of weapons the weapons 'kill' zones are also displayed on the screen, for your aircraft, your wingmen and the enemy. Although I was only allowed to assess generic weapons envelopes the principle was outstanding and allowed some highly sophisticated combat techniques to be developed and used. These included knowing when to retreat when you where getting too close to your enemy's lethal weapon zone, allowing a wingman to engage him until such time that your aircraft could again be manuvred into your own firing position.
Data-link Concepts (back to top)
The ability to data link information in a combat environment opens up many capabilities that just were not available to the pilot or to the Air Commander on the ground. The types of data that can be transferred are described above. However, it is, perhaps, what can be achieved with this new amount of tactical information that is really exciting. For example, one package of aircraft can attack a target, obtain a radar picture of the target area and then relay that picture directly into the cockpits of the next wave of attack aircraft. These next aircraft will not only have a very good picture of the target area but they will also know which target has already been attacked. As a further capability these following aircraft can also relay all this information back to the 'bunker' where the Air Commander is making the 'big picture' decisions about how the situation is progressing and what should be done next.
A more imaginative use of the capability is to send a reconnaissance aircraft to 'picture' the target area from a safe distance and then to relay this back to the attack package giving them excellent situational awareness of what they are about to encounter. Taking this a step further it is possible for one aircraft, from a safe distance, to transmit a radar picture of the target directly on to the radar screen of the attack aircraft. The attack aircraft can leave his radar switched off, approach the target covertly, and carry out the attack without ever turning on his radar. The weapon can even be guided from the first aircraft's radar. This means that the enemy target will not even know that the attack package is sneaking up on them and will not realize where the weapons came from. I had a chance to actually perform this type of attack in the air - not with real bombs and missiles though!
FUTURISTIC AIRCRAFT DESIGN (back to top)
To enable a single-seat aircraft to operate in the modern combat environment special attention has to be given to cockpit design and the basic drivers have to be simplicity and low workload. If the resultant aircraft is to be affordable, with a reasonable size and low maintenance, advanced aircraft design and materials have to be considered. To some extent the rule book has to be thrown away and a clean sheet of paper used. The Swedish have always been relatively novel in their design philosophy, and the Gripen is no exception. The aircraft uses a canard design, is very small for its capability, has a triple-channel digital fly-by-wire control system and is unstable throughout the majority of its flight envelope. The fly-by-wire system has two backup modes in case of system failures.
Why Canards (back to top)
For conventional flight all the forces and moments around the aerodynamic centre of an aircraft (the neutral point) have to be balanced. Because the centre of gravity of the aircraft is normally forward of this aerodynamic centre an anticlockwise moment develops; therefore, in order to stabilize a conventional aircraft in normal flight the tail at the rear (aft of the aerodynamic centre) has to produce a 'down-load', which creates a clockwise moment that balances the centre of gravity moment. This stops the aircraft rotating about the aerodynamic centre - the aircraft is then in trimmed flight. The problem with this arrangement is that the 'trimming' force from the tail acts in the opposite direction to the lift - overall, the lift is reduced. If the 'tail' is moved forward in front of the centre of gravity it has to produce a force in the opposite direction to counter the centre of gravity moment. The canard as it is now called, therefore, produces a force in the same direction as lift when it is trimming the aircraft. The net result is more total lift for the aircraft when in trim rather than a reduction in the total lift.
Other benefit areas include the ability to move the canards when the gear is lowered to produce more lift; this needs the elevons to also be moved (down) which produces even more lift - the result is more lift for a particular speed and angle of attack. During turning flight the canard is used as the control to produce the extra force required to turn and the elevons are used as the trimming devices. Therefore, the elevons are deflected down instead of up (as they would be in a conventional aircraft); again, this adds to lift instead of reducing it. Another benefit is that if the canards can be used independently then they can be used to augment the rudder should it fail or suffer battle damage.
This is not new technology; indeed, the Wright Flyer had a similar configuration - the difference was that the technology of the day was not powerful enough to make it work. Although it may be possible to produce a balanced aircraft with a canard they have control problems when the aircraft experiences a disturbance. Here the canard tends to make the aircraft continue to diverge away from controlled flight instead of trying to restore the original flight conditions as a rear mounted tail would do. It was not until digital flight control systems were sufficiently mature that the computers could be made to control this divergence instead of the pilot having to do it, like in the Wright Flyer. With these high-speed computers the pilot is unaware of the problems associated with canards, thus allowing the designer to exploit all the benefits that the canard can offer. It is interesting that more and more advanced aircraft are using this canard configuration: Rafael, Typhoon and some of the new Russian designs, for example.
Cockpit Design (back to top)
From a pilot's perspective the most important part of the system is the cockpit design. This is the human interface with the aircraft's systems. If the aircraft is to be truly multi/swing role then this interface must be simple and intuitive. Also, if possible, the tools in the cockpit must help in the decision making process. Here is where SAAB have really excelled. The cockpit is an ergonomic delight, made up of three 5 by 6 inch screens (12.5 x 15 cm), a wide angle (22 by 28 degrees) head up display (HUD) and just below the HUD a Mode Select Panel. The left-hand screen is a multi-function screen that is menu driven to display such things as the head down instruments, systems information and so on, it can also be used to display the HUD. The centre screen, as described above, is the tactical display, which is a situational awareness tool, giving the pilot the information he needs to decided upon the best course of action in the combat environment. The right-hand screen is the radar screen, which displays either the on-board radar picture or a data-linked radar picture from another aircraft. It is on this screen that a target would be selected, eventually locked up by the radar and then attacked. The Mode Select Panel just below the HUD allows easy selection of mission related tasks (different weapons, waypoints, etc). There are also standby instruments should the main instruments fail.
The centre stick is a 'midi' stick about the same size as a side-arm control (8 inches, 20 centimetres). Total movement is relatively small at nine degrees forward, thirteen degrees aft and eight degrees left and right. It has an adjustable pad at its base to act as a rest for your hand. Again, this is a particularly well designed piece of technology that has an excellent 'feel' to it. Much development time has been spent on improving the stick characteristics. The control forces are well harmonized and about the right magnitude for a fighter class of aircraft. In flight is was very easy to use and did not introduce any unwanted aircraft motions like those seen on other fighters with small sticks. The ultimate test for how good a stick is, in combination with the control system, is formation flying. Any design deficiencies will show themselves during this task because it forces the pilot to work very hard - he has to go 'high gain'. The Gripen was as solid as a rock in formation. Small positioning movements were very easy to achieve, with no tendency to over--control.
Keep it Simple (back to top)
An aspect of the Gripen's design that hits you from the moment you get in is 'simplicity'. The cockpit and the systems are packed full of 'good' features, which aid the pilot with his tasks. The radar, for example, has all the automated modes you would expect in a next generation aircraft. Advanced display techniques come as standard, and the majority of functions can be selected via the throttle or the centre stick (HOTAS). This reduces the need to move the hands off the controls during the weapons delivery parts of the mission. The throttle assembly had all the radar switches on it and the stick housed the weapons switches.
One example of the thought and imagination that has gone into the cockpit design is the throttle assembly. In a radar equipped aircraft there are three controls that need to be continually manipulated. These are the stick, the throttle and the radar 'joystick' controller. These latter two controls are normally separate controls or a combined 'roller-ball' system grafted on to the throttle assembly. In the Gripen the joystick is mounted on top of the throttle unit (which has a novel design in its own right), allowing movement of the throttle while still using the radar controller - very difficult to describe but very easy to use!
Another good feature is the cursor control (equivalent to the mouse pointer on the screen). The cursor can be used on the centre and right head down screens as well as the HUD. However, instead of having three cursors, one on each display, there is just one, controlled by the joystick. If the cursor is on, say, the centre screen and you want to use it to designate a target looking through the HUD, the joystick is used to move the cursor 'up' to the HUD from the head down screen. Once in the HUD the joystick is still used to move the designating cursor over the desired point - very novel and very intuitive to use.
Flight Planning (back to top)
All the flight planning, including the route and tactical information, is performed on automated planning devices in the Squadron. These planning tools allow threats to be positioned on the map from intelligence gained from other sources. They allow all the planning data to be calculated without the laborious work that was previously needed. When the route, and the threat information, is complete it is loaded on to a tape and taken to the aircraft. It is a simple process to load all the information in to the aircraft's computer via a cockpit data loader. This is not a new system, but it again cuts down the pilot's workload. Of course information can always be loaded manually or via the 'joystick' if required.
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