New engine sends shock waves through auto industry

Discussion in 'Hybrid' started by Pericles, Apr 9, 2011.

  1. CDK
    Joined: Aug 2007
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    Location: Adriatic sea

    CDK retired engineer

    You exaggerate things Jeremy.
    Jets need a lot of rpm to keep the fire going, but at 50% throttle they do not stall at ground level. I guess the actual consumption is even lower than 50% at that setting.
    But it rules out any vehicle application where piston engines are in use now.
     

  2. Jeremy Harris
    Joined: Jun 2009
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    Location: Salisbury, UK

    Jeremy Harris Senior Member

    I didn't mention anything about stalling (which doesn't happen, anyway, with this type of engine, if you ignore compressor surge that can occur under extreme conditions and is effectively an internal stall) just that the SFC was high when running at ground idle. The civil chaps don't do this for long, as they're not supposed to load people or gear on and off with the engines running, but we used to do it from time to time on trials work and I can assure you that the fuel burn was high enough to cause concern when stuck on the ground for half an hour or so between sorties. With the power levers at idle the props were automatically at zero pitch, so the power demand was low; the problem was simply one of the engines being horribly inefficient when running fairly cool and at ground level. Mind you, these were old technology compared to modern fuel efficient engines, which undoubtedly exacerbated the effect. The worst offender I can recall was the old Astazou 16D, we used to joke that it burnt more fuel on the ground than it did in the air. This was pretty clear to people outside too, from all the incompletely burnt fuel being chucked out the back.
     
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