Catapults have been part of warfare for a long time. Our ancestors used them to propel heavy objects – or sometimes their own troops – over castle walls, and now, in the 21st century, the US military has developed one to launch a state of the art reconnaissance vehicle.
The pneumatic catapult, capable of accelerating an aircraft from 0 to 100km/hr in just 0.2s, has been developed with the Dragon Drone UAV (Unmanned Aerial Vehicle) in mind.
Designed by BEI Aerospace, this delta wing drone is made from lightweight composite materials and powered by an efficient 2-stroke gasoline engine. Normally, two personnel would operate the craft; one controlling the programmable autopilot system, and the other the payload, usually a daytime or night vision system.
However, to minimise the engine size, eliminate the need for an undercarriage, and generally make the drone as fast and light as possible, BEI had to develop an innovative launch system. This is where the catapult comes in.
Two rodless cylinders from Hoerbiger-Origa form the core of the launcher system.The two 80mm diameter units with a 3m stroke fully support the drive and launch platform. The launcher is charged to about 8bar pressure using bottled nitrogen or compressed air from a light duty mobile compressor. Control valves and air supply lines provide the highest possible flow rates and response, ensuring that the drone is accelerated to a minimum flight speed of 100km/hr by the end of the cylinders’ stroke. This requires an average acceleration of 131m/s2 over just a 0.2s period.
Deceleration of the launch platform and piston assemblies is then achieved using hydraulic shock absorbers in the cylinder end caps.
The use of rodless cylinders means the launcher can cope with the rapid deployment of drones in quick succession, and it eliminates the dangerous and expensive use of consumable launch pistons and interface hardware. It is readily adaptable for shipboard use.
Hoerbiger Origa Tel: 01684 850000; Fax: 01684 850555
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