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A comment on An aircraft with a parallel hybrid engine has been successfully tested in the UK. Parent comment

Re:An aircraft with a parallel hybrid engine has been succes... by seanp2k2 on Tuesday December 23, 2014 @01:27PM (#8789382)
Hmm, I always thought that Atkinson cycle engines like they use in most hybrid cars[1] were, like "normal" Otto cycle engines, more efficient at low-ish RPMs, hence why cars tend to have low RPMs at freeway cruising speed. The figure in [2] is 2500-4000 RPM, which is definitely "normal" freeway RPM for most cars. [2] also talks about why engines like those used in most modern hybrids are not actually true Atkinson engines.

1. http://en.m.wikipedia.org/wiki/Atkinson_cycle 2. http://www.curbsideclassic.com/blog/the-atkinson-and-miller-...

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Re:An aircraft with a parallel hybrid engine has been succes... by lutorm on Tuesday December 23, 2014 @02:19PM (#8789702)
Otto engines tend to have the highest efficiency at low RPM but also at full throttle. Since car engines have to be designed to have much more power than necessary for cruising, it's not possible to use that operating point unless you use it in a (series) hybrid.
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