Rolls-Royce Announces Hybrid-Electric Demonstrator

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Rolls-Royce has announced that it will be working on a flight demonstrator based on its hybrid M250 propulsion system. The company is developing the demonstrator in partnership with Germany-based aviation engineering company APUS and the Brandenburg University of Technology (BTU). The three-year project is being funded through the Brandenburg government’s regional program to develop research, innovation and technology (ProFIT).

“We have already ground tested the hybrid version of the M250 gas turbine in a demonstration setting in Series Hybrid, Parallel Hybrid and Turbo-Electric operating modes,” said Director of Rolls-Royce Electrical Rob Watson. “The M250 hybrid is planned to be used as a propulsion plant with power ranging from 500kW to 1MW and has the potential to transform aviation power.”

According to Rolls-Royce, the M250 gas turbine engine has powered more than 170 helicopter and fixed-wing aircraft models, logging in excess of 250 million engine flight hours. For the hybrid-electric demonstrator project, the M250 will be integrated with a high energy density battery system, electric generators, power converters and an advanced power management and control system. An APUS i-5 aircraft will be used to “demonstrate the practical application of hybrid electric technology for a 4000-kg [about 8800-pound] conventional takeoff and landing flight test vehicle.”

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7 COMMENTS

  1. A consequence of the law of conservation of energy is that a perpetual motion machine of the first kind cannot exist. It’s a turbine powered plane and will get less mileage due to the fact that there will be added losses in converting to electric and also electrical losses. This will demonstrate the law of conservation of energy.

  2. Interesting design which looks amazing similar to the Hughes XF-11. Of course, the APUS I-5 should get a little better fuel economy than the P&W 4360’s that powered the XF-11.

    How much performance improvement such as range, thrust, rate of climb, etc the electric power packs/motors/ESC/batteries add to a Jet A thirsty turbine, especially at lower altitudes remains to be seen.

    But a flying hybrid prototype has to start somewhere. It appears a lot of off the shelf components will be used.

    Kind of interesting the “marketing speak” such as “The M250 hybrid is planned to be used as a propulsion plant with power ranging from 500kW to 1MW and has the potential to transform aviation power.” Just a kerosene burner turning a generator or two to power a bunch, few, lots, maybe two electric motors directly or via batteries and/or using a combination of Jet A powered thrust and electric propulsion. Since they got a fair amount of funding from the Germans, and RR did buy Siemens, it should produce a flying airplane on the EU tax payers dime. Not a bad way to help cover R&D costs for RR. I wonder how the tax payers feel about that?

  3. I would expect the major benefit will be that one is able to use the turbine under optimal conditions (at altitude) and operate on the batteries at lower levels. This could allow ground charging, electrical take-off and landing and turbine-assisted cruise extension. This would reduce the noise footprint, something towards which most local taxpayers would probably be happy to make a contribution.

    • Ground charging takes time – LOTS of it.
      That’s antithetical to the airline gate operations paradigm.

      Meanwhile, a turbine loses power as it climbs; batteries and fuel cells do not.
      Electric motors are efficient. Rotating propellers… There’s your challenge, regardless of what’s swinging them.

      There’s no free lunch. Reduced-price lunches are elusive. Don’t allow your means to obscure your objectives.

      • “Ground charging takes time – LOTS of it.
        That’s antithetical to the airline gate operations paradigm.”
        My 2005 design for a two seat single engine electric trainer used quick-disconnect belly battery trays ferried in and out from charging station on glorified laundry carts. Pretty sure those in service have variations on that now. Scale up. For airline gate ops would take a fork lift…

  4. Mark F said, “It’s a turbine powered plane and will get less mileage due to the fact that there will be added losses in converting to electric and also electrical losses.”

    Electrical losses should be insignificant (typically 2% or less between the generators, wiring, and motors). The turbine engine could be sized such that it provides only slightly more than the power required for cruise flight. Takeoff and climb would be accomplished using the turbine and the batteries. In cruise the turbine would provide cruising power and a tiny bit more to recharge the batteries in support of a possible missed approach or go-around at the end of the flight.
    There is an aerodynamic efficiency to be found in distributed propulsion, so one tick mark for the ‘gain’ column there.
    No, not perpetual motion, but efficient motion perhaps.

    • Saying electric has 2% loss ignores the entire system; it reminds me of salesmen of the 50’s and 60’s lying about their horsepower ratings of V8’s. What you did not include are all the losses of creating, storing and converting electricity AND the losses associated with a gas turbine. It’s actually less energy efficient.

      Just remember, when you do that missed approach near the end of your flight, you STILL have all the weight of those batteries to lug back up into the air. Did you calculate that loss of flying efficiency in that 2%? As said, the whole system ends up being less energy efficient when you add TWO propulsion systems AND do more work.