The Future of Advanced Air Mobility

RED Aircraft Positions Its High-Performance Piston Engine for Hybrid-Electric Propulsion

Raikhlin Aircraft Engine Developments (RED Aircraft) is positioning its A03-series piston engine not only as a step forward in general aviation propulsion but also as a new option for hybrid-electric powertrains. First certified by EASA back in 2014, and then by FAA in 2016, the 500-hp A03 is still the most powerful piston engine on the market, and, according to the German company, it also offers lower fuel burn and carbon dioxide emissions.

In April, Hybrid Air Vehicles (HAV) selected the A03 to power its Airlander 10 airship. Initially, the UK company intends to use four of the piston engines to replace diesel engines now powering its technology development aircraft, with two installed on the stern of the airship and one each on the port and starboard sides.

HAV’s plans subsequently envisage a switch to a hybrid-electric configuration in which two A03s would work in tandem with a pair of 500 kW electric propulsors. Eventually, as electric battery technology advances, the company may introduce an all-electric version of the helium-filled Airlander, although that would limit the range to just over 200 miles. In some applications, the airship potentially could operate over more than 4,000 miles.

The A03, which weighs just over 800 pounds, is also powering Otto Aviation’s innovative Celera 500L aircraft. The California-based developer says the six-seat, fixed-wing model will be able cruise at speeds of around 450 mph, which would be unprecedented for a piston-powered aircraft. The pusher-prop design is also expected to deliver a range of more than 4,500 miles when it enters service in 2025.

Like HAV, Otto views the A03’s V12 twin, six-cylinder piston engine as an ideal platform for its efforts to transform current levels of performance for general aviation aircraft. Similarly, the start-up also has plans to later develop electric and/or hydrogen-powered versions of the Celera 500L.

Powered by the A03, the bullet-shaped model will get between 18 and 25 miles per gallon, and operating costs will be around $328 per flight hour. The Celera’s superior projected aerodynamic performance is largely based on laminar flow over the fuselage, wings, and tail surfaces.

According to head of sales and customer support Enrico Evers, this level of fuel efficiency is more comparable to a medium-sized car than a transcontinental aircraft. “To explain how incredibly efficient this is, a light business jet performing the same task would generally operate at around three miles per gallon,” he told FutureFlight.

RED Aircraft developed the A03 as a completely clean-sheet design to provide a cost-efficient and environmentally sustainable alternative to both older radial engines and turboprops. Its “common rail” architecture consists of 12 cylinders arranged in a V-formation so that each bank of six cylinders can function independently.

In hybrid-electric applications, the A03 can be readily installed in a location well-suited to the center of gravity for almost any aircraft to act as a turbogenerator powering electric motors. It can be used to charge batteries, extending both range and payload.

The engines also can be used to retrofit existing Part 23- or Part 27-certified aircraft under supplemental type certificates. For instance, this month a Yak-18T trainer aircraft flew with an A03 installed, following recent approval by Russian aviation authorities.

RED Aircraft is based at Adenau in the west of Germany, close to the Nürburgring car racing circuit. The company was founded in 1995 as Raikhlin Engine Developments and has extensive experience in the automotive industry, providing high-performance engines for manufacturers including Toyota, Porsche, and Mercedes.