Rolls-Royce has flown a Boeing 747-200 testbed with an engine demonstrating the company’s newly-developed low-emissions combustion system, known as ALECSys, which forms part of the UltraFan programme.
ALECSys is centred on a system which improves fuel-air pre-mixing before ignition.
This allows “cleaner” combustion of the fuel, says Rolls-Royce, leading to reductions in nitrous oxide and particulate emissions.
The flight phase of testing, which commenced at Tucson in Arizona, included cruise at 40,000ft and successful engine relights under various conditions. It will allow the company to assess performance at altitude and enable improvement in maturity before entry into service.
Rolls-Royce has already carried out a series of ground tests on the engine, among them icing and water ingestion, and compatibility with wholly-sustainable fuel.
“Flight testing is a key part of our drive to not only improve engine efficiency but all aspects of environmental performance,” says civil aerospace director of product development Simon Burr.
The 42-year old testbed, N787RR, carried the demonstrator on the inboard left-hand pylon. Its other three engines are Rolls-Royce RB211s.
Rolls-Royce intends the UltraFan to offer a 25% saving in fuel-burn over first-generation Trent powerplants.