Despite searching since last year for a new Block III engine for its Textron Systems RQ-7B Shadow UAVs, the US Army is still no closer to finding a suitable powerplant.

When the US Army first fielded the RQ-7B in 2015, it weighed about 127kg (280lb). Over the years, the service has added mission equipment and improvements to the unmanned air vehicle that have also added weight, bringing the platform close to 226kg. Last year, the army began its effort to replace the current UEL AR741-1101 engine.

Lt Col Tory Burgess, the US Army's tactical UAS product manager, told FlightGlobal at the annual AUVSI Xponential show in Dallas, Texas that when the service released its request for information, several industry representatives said they had no engine at a suitable technology readiness level,

The heavier Shadow is now too big for battery power and yet too small for a turbine engine, Burgess says, and the industry feels caught in the middle.

“The response we got back was, there’s a lot of engines at different stages of technological readiness but they’re not ready to go on the Shadow right now,” he says. “Honeywell, Rolls, GE, Pratt… there’s no business case for them to invest millions of dollars into an engine in that class when we’re only buying engines at $60,000 a pop.”

The army is pushing industry toward its reliable advanced small power systems (RASPS) programme, which will invest in an engine for the service’s group 3 tactical UAS inventory.

Although it plans to invest $20 million into the RASPS programme, Burgess says industry feels there is not enough of an incentive to create an all-new engine.

Michael Hahn, senior business development director of tactical UAS at Textron Systems, says: “It’s too low of a quantity in order for a core engine company to go after that.

“[The engines] are not at tech readiness level of maturity to be produced and put out to the fleet today. There’s still developmental work to prove statistically that the reliability is there.”