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Interesting Engines:
The Rolls-Royce Goshawk

January 28, 2013 by Matt

Rolls Royce RR Goshawk

A few years before the development of the world-beating (and war-winning) Merlin in the late ’30s, Rolls-Royce released this turd of a powerplant.

The Goshawk was a 21-liter, 600-hp V12 engine developed to power the fighters bidding for the 1934 British F7/30 specification. As it turned out, all eight of the designs submitted turned out to be completely unsuitable for combat even before they left their respective drawing boards, their immediate obsolescence caused in no small part by the Goshawk’s inherent design flaws. In fairness, the British government’s specification was remarkably backward-thinking and short-sighted in many respects, but the fact that Rolls-Royce powerplant was totally inappropriate for a fighter should have been obvious to any casual observer.

Hawker P.V.3. F7/30 Fighter

Fitted to the Hawker P.V.3. shown above, among others, the engine’s basic design was decent; it was the inclusion of a trendy design feature that doomed its prospects: Evaporative, or steam cooling. Instead of a conventional pressurized water cooling system, where the coolant is kept in a liquid state past its boiling point, the Goshawk was built around the principle that letting the coolant actually boil would absorb more heat by virtue of the energy needed for the state change from liquid to gas. The upshot would be less coolant capacity required, and while the principle was sound, in practice the system suffered from at least two major flaws:

  • Radiator size. The actual amount of coolant making the rounds in the pipes may have been less than that of a conventional setup, but the radiator (in this case, condenser) capacity needed to allow the gas to condense back into a liquid was much greater, posing insurmountable difficulties when it came to integrating them into the airframe with an acceptable amount of drag.
  • Total unsuitability for combat maneuvers. The Goshawk, with its steam cooling system, was intended primarily for fighter aircraft, a type designed with a high level of agility, including negative-g maneuvers and inverted flight. It’s obvious what kind of problem this flight behavior would pose to a cooling system dependent on gas and liquid to occupy specific locations in order to operate properly—the mildest movement would cause the steam and liquid to trade places and completely ruin the effectiveness of the system.

Successful? Hardly. Interesting? Sure. Oftentimes engineers learn as much from what doesn’t work as what does, and viewed from an historical perspective, it’s perhaps fortunate they learned “the hard way” from the Goshawk’s difficulties before the more urgent days of the late ’30s arrived.

Image credits:,

Editor’s note: This post is part of an ongoing series examining unique and significant powerplants. Read the other installments here:

Filed under: Interesting Engines, Rolls-Royce, Technical


  1. John D says:

    Great read. I love hearing about past successes and failures of engineering. Keep it up!

  2. Aaron says:

    Wow – neat bit of aviation engineering trivia…I think that I recall from a thermo or heat transfer class that the enthalpy of vaporization of water is quite high, which would theoretically make this an efficient cooling system

    • Matt says:

      Very true. It takes quite a lot more energy to get that liquid to vaporize than it does to get it to 212°F in the first place. Just wouldn’t work too well for a fighter that would spend time inverted, negative g, all that…

  3. Durty says:

    When you said steam cooled at first I thought they put water directly on the block to cool. I was wondering why that would require less water because you would be losing the water as it ran. Thanks for the bit of history, I love the blog!

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