Actuator designed for opening emergency doors

Monday, 11 August, 2008


Weight minimisation is a particular challenge in the construction of jets. Aircraft doors are a critical factor in this weight balance. The safety-sensitive classified emergency opening systems are an area where highly specific weights and costs are demanded.

This is where the ambitious research project Pyrotak comes in. It is a collaboration of research projects from Bavarian businesses and universities which are already a success. The participating businesses and universities under the direction of consortium leader Eurocopter Deutschland GmbH, Donauwörth, want to develop a new door actuator which in an emergency opens the doors of wide-bodied aircraft such as the Airbus A350 extra-wide body. Additionally, this innovative concept provides the potential to upgrade the existing fleets of aircraft such as the A300, A320, A330/A340 or A380 families. It is also possible to apply this to broader uses within the field of actuators which have a similar application profile in the air industry, such as emergency opening systems for aircraft passenger doors.

The starting point is to look at the previously known procedures for emergency openings of aircraft passenger doors, electronic or pneumatic, such as those used in the Airbus A380. However, these are not the best options in terms of weight, maintenance expenses, complexity of the electronic system and the energy density.

Pyrotechnic propellants have not yet been developed sufficiently in aeronautics; the full economic potential of this drive option has been so far unused. The aim of Pyrotak is the development of a pyrotechnic rotary drive system for the opening of passenger doors when, in an emergency,  the doors must be relied on to open automatically.

The introduction of totally innovative technology such as pyrotechnics for rotary actuators requires an extraordinary amount of cooperation between science, research and industry. Eurocopter Deutschland GmbH is a leading manufacturer of doors and cargo doors for commercial aircraft, especially for Airbus. On board for the development of the pyrotechnic door actuator are various universities and companies.

The development of pyrotechnic propellant is the responsibility of the company HS Product Engineering in Alling. A particular challenge is to gain insights into the use of pyrotechnics for slow operating systems.

Further scientific assistance for the project comes in the form of Prof Johann Höcherl (Validation) and Prof Dr rer nat Michael Pfitzner (Thermodynamics), both from the University of German Federal Armed Forces in Neubiberg.

Prof Dr-Eng Bernhard Frenzel and Prof Dr Peter Kurzweil, both from the University for Applied Sciences Amberg-Weiden, are responsible for the conception and design of the ignition device. The pyrotechnic propulsion unit which is activated by the ignition device supplies the motor with the necessary working gas. The rotating actuator drives the aircraft doors.

There are two different drive concepts in the collaboration research project: a direct gas motor and an indirect gas motor which is equipped with an additional reduction gear.

The flow mechanical design of the gas motor is undertaken by Prof Dr Eng Andreas P Weiß of the University for Applied Sciences Amberg-Weiden.

The concept of the direct gas motor is to be devised by the engineers of the Bavarian company HS Product Engineering.

The pyrotechnic ignition indirect motor with reduction gears is, however, created in the development laboratory of Deprag Schulz GmbH & Co. The central element to this tool is the air motor as drive unit. Depending on application, an air vane motor, tooth wheel motor or turbine drive can be used. For the research project, the turbine drive is most suitable, as this has the highest power density and allows oil-free operation.

High drive performance can be achieved in the smallest spaces and with low weight by use of a suitable turbine motor. Up to 4 kW capacity can be realised by a machine which weighs less than 2 kg. These characteristics make the Deprag turbines compatible for use in the emergency door system.

The Deprag engineers are now developing a pyrotechnic ignited gas motor with reduction gears which should deploy its torque directly on the door opening drive.

Last, but not least, the Bavarian company Elektro-Metall from Ingolstadt has taken over the constructive integration of the actuator unit.

 

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