Manifold Pressure Values?????

by geoffrey klestadt in 912iS Technical Questions 8 years ago

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Re: Manifold Pressure Values?????

by Gilles Thesee » 7 years ago

Gilles Thesee

2 9 0

If this were true then the engine may be running the same as a carburettor 912 engine and then the manifold pressure and rpm settings for that carburetted engine with constant speed propeller would perhaps be appropriate.

Geoffrey and all,

At last we got the answer to this nagging question.
As already stated, there is no magic in an injection engine, and once the fuel is metered, be it electronically, mechanically or "carburetically" (!), nothing changes for the pilot, and Rotax gave manifold pressure vs power tables, very close to those of the 912 ULS.
Such a table was present in the first edition of the Operator's Manual as it should be, except that the people in charge of publishing the manual confused MP values with FF values !

Long story short, the issue was raised by French owner Sylvain Andrieu in a long forgotten post (3 years ago), and he finally got the values in a message from Rotax :

Hi,

I just received the answer of Rotax Cie :

"Dear Sir,

I thank you for your email below.

You are indeed right : the manifilf pressure values in the operators manual are not correct, and will be changed in the next issue as follows :
take-off power : 29 in.HG
max.continuous power : 27 in.HG
power setting 75 % : 26 in.HG
power setting 65 % : 26 in.HG
power setting 50 % : 24 in.HG

I thank you for your remark. "

Also

So the new values for the 912 iS indicated by Rotax Cie are exactly the same than the 912 ULS values.
The only difference is for take off : 29 in.HG for the iS and 27,5 for the 912 ULS.

See topic
http://www.rotax-owner.com/en/rotax-forum/is-technical-questions/4614-912-is-performance-table-is-wrong

Instead of updating their manual, Rotax just omitted the values in the current manual. Let's say their staff in charge of manuals are, well, below average.

Best regards,
Gilles

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Manifold Pressure Values?????

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