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Manifold pressure gets up to 29.7

  • Ed R
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1 month 1 week ago #17242 by Ed R
Ed R created the topic: Manifold pressure gets up to 29.7
I have a Rotax 912 ULS and will be installing a constant speed propeller later so I recently installed a manifold pressure gauge. I notice that on take-off my MAP gets up to 29.7 in-Hg (at 5600 rpm and full throttle). Is that acceptable? The manual suggests take-off should be 27.5 at 5800 rpm and maximum sustained power should be 27.0 at 5500 rpm, but it does not state whether the RPM limits are the only limits to respect or whether manifold pressure must be as well.

In other words, aside from wondering is 29.7 is excessive / unsafe, is it OK to cruise at < 5500 rpm and > 27 map pressure? When I get the constant speed prop I plan to cruise at 5100 rpm and potentially full throttle so that's why I ask.

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1 month 1 week ago #17243 by Peter Kl.
Peter Kl. replied the topic: Manifold pressure gets up to 29.7
Hi Ed,
Rotax has issued a chart recently that describes the flight envelope for rev and map. That chart answers all questions, I'd say.
Regards
Peter
The following user(s) said Thank You: Dennis Richardson

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1 month 1 week ago #17244 by Peter Kl.
Peter Kl. replied the topic: Manifold pressure gets up to 29.7
Pls refer to SL-912-016R1, page 5

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1 month 1 week ago #17246 by Ed R
Ed R replied the topic: Manifold pressure gets up to 29.7
Thanks. Their chart shows an expected map of just above 29 at 5600 rpm but it also says manifold pressure limits don't matter above 5200 rpm; only <= 5200 rpm should I reference that graph. Makes things clear. Thanks!

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