The latest test of Horizon Energy System's AEROPAK fuel cell power system has seen it fitted aboard an Elbit Systems Skylark I-LE UAS (Unmanned Aircraft System) and put through its paces. Although the AEROPAK has been put to the test in other UAS aircraft, the official test flight recently carried out in Israel marked the first time a fully operational system using the AEROPAK - including take-off and recovery with an operational payload integrated onboard - has been tested.

The Skylark I-LE is an electrically-propelled, tactical, silent, man-portable UAS that entered operational service in 2004 and is currently used by several countries for close range surveillance and reconnaissance missions. Elbit says equipping the aircraft with the AEROPAK fuel cell system will double the current flight duration of the UAS.

Horizon's AEROPAK power system is designed as a drop-in replacement for battery packs used in small electric UAS aircraft and delivers 900 Wh net usable energy per liter of fuel.

To test the limits of the system, the test flight simulated real battlefield conditions and an actual payload. The Skylark's AEROPAK-enabled propulsion engine was subjected to a number of operating scenarios including repeated take-offs and abrupt landings on various terrains to determine if the fuel cell was able to withstand high levels of shock. The UAS was also flown in windy and turbulent weather to gauge the AEROPAK's capability to sustain continuous high power drain from the aircraft's motor.

Elbit says the AEROPAK fuel system passed the tests with flying colors, proving it is rugged enough for military use.

"The AEROPAK has passed Elbit Systems tests and is now proven to be a ready drop-in replacement for battery packs currently in use. We are immensely proud of this achievement and believe that the AEROPAK powered Skylark I-LE will be an unparalleled combination," added Richard Liow, UAS systems manager at Horizon Energy Systems.