Pressure flies high in the EuroFighter

The Eurofighter Typhoon project will come to fruition with delivery of the first tranche of airplanes early in the next Millennium. Colin Carter looks at the use of pressure sensors in the fuel management system and within the hydraulic systems

Pressure transducers find uses in many diverse applications from the mundane, to use in technologically advanced projects such as in the Eurofighter Typhoon aircraft.

The Eurofighter Typhoon project was conceived in the 1980s to provide a multi role aircraft (i.e. with air to air as well as air to ground strike capacity) by a consortium of European nations to counteract the perceived threat of the Eastern Bloc at that time. Since then the Cold War has ended and the consortium now consists of partners from Germany, Italy, Spain and the United Kingdom. The project involves some 150,000 people working in 400 companies across the four countries; the UK, which is planning to buy 232 aircraft from the initial production of 620, will have 34% of the production workshare. Part of this work will be the supply of pressure transducers for the aircraft, the uses of which are described later.

EUROFIGHTER FACTS

The Eurofighter Typhoon is capable of flight at over 1500mph; as an illustration this is faster than a speeding bullet, or capable of flying from London to Paris in eight minutes. The pilot has use of a voice activation system (called Direct Voice Input) which enables him to control aspects of the aircraft’s operation using voice commands. The pilot also has a helmet mounted display (HMD) system which allows the pilot to direct and fire a missile simply by looking at the target. The Typhoon is capable of recognising aircraft from 100-200 miles away.

For weaponry the Typhoon typically carries an internally mounted 27mm Mauser gun and a mix of Beyond Visual Range Air-to-Air missiles (BVRAAM) and Short Range Air-to-Air missiles (SRAAM) carried internally and externally. A full range of Air-to-Surface weaponry including laser guided bombs, advanced anti armour weapons and conventionally armed stand off missiles are available.

USE OF PRESSURE SENSORS

The Eurofighter Typhoon uses pressure sensors in two critical areas, for fuel management across the tanks in the fuselage and wings of the aircraft and to monitor hydraulic pressure and feed back information into the flight control system.

In the Eurofighter Typhoon, fuel is contained within three main areas of the aircraft; fuel tanks are located within the fuselage itself and within the wings. As the aircraft manoeuvres in the air fuel naturally moves under gravity from one side of the plane to the other, with obvious consequences for the stability of the aircraft. To counteract these movements and the stability problems, pressure sensors (2 Druck type PDCR 380 transducers) spaced around the fuel tanks detect the difference in fuel weights within the tanks and feed back a signal to a control system. This control system then activates fuel pumps which balance fuel distribution across the aircraft.

HYDRAULIC SYSTEM SENSORS

In the Eurofighter Typhoon, pressure sensors are used to monitor hydraulic pressures in areas such as the landing gear, the ailerons etc.

The Eurofighter Typhoon is designed to be dynamically unstable with respect to pitch in flight; a configuration which is considered optimal with the delta wing shape of the Eurofighter. Adjustments are made to the airframe control surfaces continually by the computer controlled hydraulic system as the aircraft flies. This system uses closed loop control to adjust elevation according to pressure readings from the transducers and enables the aircraft to perform advanced complex combat manoeuvres with the speed, ease and precision required of a modern fighter aircraft. The hydraulic control system employs 16 Druck type PDCR 360 and PDCR 370 pressure transducers per aircraft. These pressure transducers communicate directly with the aircraft’s flight computer using a digital interface. As the hydraulic system pressure transducers are used in a safety critical role double or triple redundancy is built into the system.