The US Defense Advanced Research Projects Agency's (DARPA's) LightningStrike vertical take-off and landing (VTOL) X-Plane programme has completed an initial flight demonstration phase with a scale model.
A subscale vehicle demonstrator (SVD) aircraft for LightningStrike completed its planned flight test programme in early March, according to Ashish Bagai, DARPA's programme manager for the effort and creator of the agency's VTOL X-Plane programme.
Specifically, the 20% scale system demonstrated the sort of technical features that a full-scale aircraft must perform - such as outbound and inbound transition flight.
DARPA selected Aurora Flight Sciences, working with Honeywell and Rolls-Royce North America, for the LightningStrike XV-24A. Bagai called the design "one of the most remarkable configurations that one could have conceived of".
The SVD flew 10 flights in vertical and wing-born modes and transitioned between those modes, Bagai said. That test run is now over and officials will next focus on a full-scale system demonstration.
Carl Schaefer, Aurora's programme manager for XV-24A, said the SVD is a 325 lb (147.4 kg), lithium battery powered scale model with a 10.7 ft (3.2 m) wingspan, capable of flying at 100 kt. "It did validate our aerodynamic approach to this," he said of the scale model testing.
The XV-24A will be closer to 12,000 lb with a 61 ft wingspan, and that platform is to start its flight test programme late in 2018. The full-scale aircraft is being built now and "will be rolled out at the end of this calendar year", Schaefer said.
Bagai said the full-scale model is expected to be tested at speeds of 300-400 kt, or twice as fast as contemporary helicopters.
Notably, the effort hopes to advance electrical engines for aircraft, although it will take a hybrid approach for the upcoming full-scale model. It will use Rolls-Royce's AE 1107C turboshaft engine to power three Honeywell one-megawatt electric distributed propulsion (EDP) generators that drive 24 ducted fans on the wings and the canards, according to Mark Wilson, chief operating officer for Rolls-Royce North American Technologies (Liberty Works).
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