Colorado-based start-up Reference Technologies on 5 May unveiled a new ducted fan-powered unmanned air vehicle in the 120lb-class called the Hummingbird.

To solve the directional stability problem for classic ducted fan UAV designs, the Hummingbird adds a ring of six 17in-diameter ducted fans arranged around a 24in-wide central duct.

The UAV’s central duct contains a gasoline engine that generates electricity to power each of the seven fans.

The production-representative, gas-driven design follows an electrically-driven prototype that Reference Technologies unveiled at AUVSI a year ago, says Mark Monroe, director of business operations.

The prototype validated the seven-fan thrust and control system, but the battery power proved insufficient for the UAV’s range requirement, Monroe says.

The Hummingbird’s endurance should be 2-3h initially, but rise to 6h as the propulsion system is improved, Monroe says.

Reference Technologies plans to sell the Hummingbird to partner Flōt Systems, which provides a sensor and offers the package as a service for utility line inspections.

The Hummingbird will be branded as the “Prophex 50” by Flōt, with the 50 referring to the weight of the maximum payload in pounds.

Reference Technologies completed assembly of the first Hummingbird only a few days before the AUVSI convention started on 4 May.

The company plans to begin indoor flight testing within a few weeks. It has also partnered with the University of Colorado to use its certificate of waiver or authorization (COA) with the US Federal Aviation Administration for outdoor flight testing.

As the COA application is in process, Reference Technologies could gather some data with tethered outdoor tests, Monroe says.