The Airbus A320-232 "D-ATRA", the latest - and largest - addition to the fleet, was deployed by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) in late 2008. ATRA (Advanced Technology Research Aircraft) is a modern and flexible flight test platform which sets a new benchmark for flying test beds in European aerospace research - and not just because of its size.
Fuel cell system implemented for auxiliary power supply
Together with its project partner, Airbus, the DLR Institute of Technical Thermodynamics (DLR-Institut für Technische Thermodynamik) has equipped the aircraft with a Michelin fuel cell system. The integrated fuel cell can provide auxiliary power for one hour - and without any carbon dioxide or other pollutant emissions. During emergency operation, the system can operate the pump of one of three hydraulic systems, which move the control surfaces in case the engines shut down.
In order to be able to install the 20-kilowatt fuel cell in the cargo compartment, the DLR research aircraft was first equipped with a cargo loading system. The fuel cell system then needed to be connected to the aircraft and its electricity consuming devices. This involved the difficult tasks of constructing a mobile infrastructure for supplying the system with fuel (hydrogen and oxygen), and of developing and implementing the approved measuring instruments for the flight test, used to monitor and analyse the behaviour of the fuel cell system during flight. Before the aircraft could take off on its first test flight with the fuel cell on board, the system had to undergo rigorous acceptance trials on the ground, to guarantee the level of safety required for air traffic.
During the usage phase, the basic configuration will be developed further and ATRA's range of applications will be extended further. Many of the future additions and alterations to the test bed will be linked to specific scientific instruments, and are thereby in part of a temporary nature. The application of widely used standards in the selection of components and structures should ensure that the requirements of modularity, extensibility, simplicity, as well as reliability and durability, are met.
Missions - research focus
ATRA will be deployed for the following fields of research:
- Testing of aeroelastic measurement techniques
- Research into inner space acoustics
- Airframe noise measurement
- Measurement of turbulence (laminarisation) at the wing and at the tailplane
- Testing of new measurement techniques such as PIV (Particle Image Velocimetry), an optical method for measuring velocity fields
- Measurement of wake vortices: tubes of circulating air which are left behind by the wings as they generate lift
- Atmospheric and engine measurements
In addition, ATRA will have several cockpit interfaces. An experimental method of driving the cockpit display, additional data links and a head-up display are implemented for this purpose. This opens up another set of research options:
- Research into flight control commands for passing through wake vortices and for load alleviation, as well as in the fields of autonomous flight, airport surface traffic control, pilot assistance and display technology
- Research into pilots' workload and division of work
- Testing cutting-edge navigation and communication technologies for aircraft and low-noise approach and departure procedures
Wake vortex research with ATRA
Air swirls in the wake of aircraft are a result of the lift generated at the wings; as invisible wake vortices, they can persist along the flight path for quite some time. For this reason, strict safety distances are prescribed in civil aviation; these determine the take-off and landing frequencies at major airports, and when the traffic volume is at a peak they can lead to capacity bottlenecks. These in turn lead to aircraft having to fly in holding patterns and to flight delays - unpleasant effects which are undesirable for passengers and airlines alike.
DLR approaches this issue in two different ways. Firstly, using the Lidar laser measurement technique, ATRA can measure the velocity field of the vortex of a preceding aircraft. Secondly, inflow sensors measure the parameters for vortex models, such as intensity and ageing behaviour. This approach has the benefit of allowing the simultaneous modelling and evaluation of the way the encountering aircraft responds to the vortex, in combination with the actual wake vortex properties. The aim of the experiments is to make smaller separation distances possible between aircraft approaching or taking off in succession, through a more precise calculation of the evolution and decay of the wake vortices.
High-lift research with ATRA for efficient take-off and landing phases
Air transport faces a variety of challenges. Due to the global increase in air traffic volume, enhancing the aerodynamic efficiency during the take-off and landing phase, as well reducing the flight noise, will become even more important than before. As a partner in a variety of national and European research projects, DLR is meeting these challenges head on.
The design and development of complex flap and transmission systems with far-reaching effects on the take-off and landing properties as well as the noise emission of aircraft, is therefore one of DLR's core research areas. In cooperation with the high-lift systems department of Airbus in Bremen, DLR explores current research questions.
|Technical data||Airbus A320 "D-ATRA"|
|Cabin length:||29.10 metres|
|Cabin width:||3.7 metres|
|Cabin height:||2.4 metres|
|Empty weight:||42.3 tonnes|
|Total weight:||maximum 75.5 tonnes|
|Engines:||two International Aero Engine V2500 engines|
|Thrust:||111 kilonewton each|
|Range:||4800 kilometres to 5700 kilometres|
|Flight altitude:||maximum 11,800 metres (39,000 feet)|
|Speed:||maximum 840 kilometres per hour|
|Endurance:||up to 2h 30m for test operation|
|Fuel tank capacity:||23,858 litres|
|Original use:||civilian use - passenger aircraft|
|DLR flight facility:||Braunschweig|