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Research infrastructure
Unique selling points of research aircraft
Aircraft that are used as research platforms must fulfil certain requirements. Science has certain basic needs and requirements for the aircraft, depending on whether it is itself the subject of research or is used as a measurement platform for researching its surroundings.
These requirements can be very high and can often only be met with considerable effort when modifying and equipping the basic aircraft. Conversely, it can be stated that an unmodified or insufficiently modified aircraft is unsuitable for research. The same applies if there is no appropriate interface documentation for the modifications.
The modifications are almost exclusively one-off changes and equipment developed specifically for the respective research application.
Examples of DLR's expertise:
- Data collection on the status and characterisation of the aircraft: avionics interfaces, experimental IRS, additional strain gauges and acceleration sensors on the structure, flow probes for pressures and flow angles.
- Measurement of atmospheric data to describe the environment and the conversion of data from scientific instrumentation to outdoor conditions (accuracy is therefore critical). In addition, wind data for direct scientific use: nose mast with precision instrumentation (fast+accurate), temperature sensors, high-precision bearing reference platforms
- Possibility of taking samples from the outside air (prerequisite for in-situ instruments): Standardised openings with inlet systems. These must have the ability to absorb corresponding inertial and air forces until a crash or bird or lightning strike occurs. Interface documentation for science and EB (introduction of moments + loads) in order to develop such modifications at all. The effort involved increases significantly for aircraft with pressurised cabins
- Interfaces for optical instruments: openings with large diameters to install high-quality optical windows and to hold the corresponding optics; several windows upwards, downwards and to the side.
- Hardpoints to mount instruments on the outside: E.g. radar systems, antennas, radiometers, special probes. In some cases with the option of external panelling (belly pod, radomes for high-frequency technology). Here too, interface documentation is of great importance.
- Placement of instruments in the free flow on the wing. Hardpoints for particle probes and sensors, which must be positioned directly in the airflow, or for optical sensors, which must look (undisturbed) in the direction of flight.
- Preparation for laying cables to/from the instruments to the measuring systems (data and power supply). This includes empty conduits, pressure feed-throughs, power interfaces in places that are sometimes very unusual and difficult to realise.
- Extended mounting options for measuring racks and instruments in the cabin: additional seat rails, special hardpoints, reinforcements if necessary to support greater loads.
- Special mission power system. This should be completely separated from the aircraft's basic system if possible and with special monitoring of voltage stability and, if necessary, emergency shutdown. Additional generators if required.
- Data up/downlink for tracking/controlling flights from the ground.
The engineering and conversion costs for such modifications are enormous and can exceed the price of the basic aircraft several times over. The lead times and phases for procuring an aircraft with complex modifications are correspondingly long. In the case of HALO, for example, procurement took over ten years, three of which were spent on modifying the aircraft alone.
These modifications, which are carried out and approved partly by the manufacturer and partly by the FX development organisation, make the aircraft exclusive one-offs. They therefore fulfil the requirements in scientific competition more frequently than other aircraft. As a result, often only individual aircraft are considered for certain experiments worldwide. The current high utilisation of the DLR research fleet is clearly due to the level and quantity of these unique aircraft.
As scientific requirements and available technologies are constantly evolving over the course of an aircraft's life, modifications are always necessary at a later date (e.g. additional generators on the Falcon, PMS cabling on HALO, ongoing project-related changes to ATRA). These are planned and developed by FX Development Operations and, if necessary, approved and installed in cooperation with external companies. Reliable and universal documentation of the basic aircraft with all interfaces and close cooperation with the manufacturer are essential to ensure that this is done reliably and smoothly.