The Discus-2c DLR heralds the start of a new generation of research gliders in almost every respect, coming in gradually to replace the reference glider DG 300 17. Its structural design demonstrates progress; while the DG is made of glass-reinforced plastic (GRP), the Discus is constructed using the current industry standard, carbon-fibre-reinforced polymer (CFRP).
The flight performance of the Discus has been precisely analysed to make it suitable for use as reference aircraft to benchmark the performance of new glider designs. The polar curves this has revealed are substantially flatter, especially in the high-speed flight regime, and are therefore ideally suited to comparing cutting-edge, high-performance gliders.
A special feature of the Discus 2c-DLR is its generous storage space for measurement electronics. To achieve this, the fuselage accommodates a large box, accessible from outside and offering space for sensors, GPS receivers and measurement systems. The sensor systems fitted to the Discus were planned in cooperation with the Technical University of Braunschweig during the aircraft procurement phase and then bonded into the exposed structural components during construction. For instance, the fuselage and the wings are fitted with over a dozen strain gauges, designed to measure the load exerted during various flight conditions. The starboard wing also houses a fibre Bragg grating with glass fibre running along the spar. This system is used to make extremely precise measurements of wing deflection.
The most visible alteration compared with the standard aircraft is the nose boom. It is fitted with what is known as a five-hole probe, which is used for very accurate measurements of the angle of attack. Additional modifications such as external load points, the cockpit display, differential GPS system and data logger ensure that the aircraft is ideally prepared as a modular measurement platform for various research projects. Future analysis will focus on aeroelasticity, in-flight parameter identification and questions relating to human-machine interfaces in addition to measuring flight performance.
|Technical data||Discus-2c DLR|
|Length:||6.8 metres (plus nose boom)|
|Total weight:||565 kilograms|
|Water ballast:||208 litres|
|Wing loading:||maximum 52 kilograms per square metre|
|Best glide ratio:||(yet to be measured)|
|Landing gear:||retractable, spring-loaded undercarriage|
|Maximum speed:||280 kilometres per hour|
|Minimum speed:||75 kilometres per hour|
|DLR Flight Operations:||Braunschweig|