Hi Bob,
I would not say that MAP is the only way to measure power when equipped
with a constant speed prop. We find that fuel flow is also a good
indication of relative power, using it probably more often than MAP.
Although with the 912 and 912s, the mixture gets richer at altitude,
making the fuel flow reading somewhat higher than at sea level, for the
same power (MAP, HP, etc.).
regards,
Terry Seaver
R.C.Harrison wrote:
>
> Hi! Richard
> I find myself a little bemused why the resistance to fitting a Manifold
> Pressure Gauge, apart from needing room on the panel? If you have a CS
> installation without the gauge you will have no indication as to how you
> are loading the engine, that is to say RPM is no longer an indication of
> power.
> So it becomes possible to run the engine at all RPM in a labouring
> condition not to be recommended for cruise configuration with respect to
> fuel consumption and engine well being. My MT CS prop. will hold the
> engine RPM at say 2,500 even with maximum MP at say 30 inches, where
> maximum recommended is about 22 inches. The rule of thumb is so called
> "squared"
> Which means 24" FOR 2,400 rpm ON A DIRECT DRIVE ENGINE. However I've
> managed to identify on the Jabiru 3300 that a lower MP with a slightly
> higher RPM gives a better fuel performance. (no snipes about fuel usage
> comparison with the Rotax thanks Duncan the scenario still applies)
> Problem without a MP Gauge is knowing the effect of the ambient and
> altitude changes and in pressure relative to engine performance.
>
> Regards
> Bob Harrison G-PTAG Europa Kit 337 MKI/Jabiru 3300
>
> -----Original Message-----
> From: owner-europa-list-server@matronics.com
> [mailto:owner-europa-list-server@matronics.com] On Behalf Of Richard
> Holder
> To: europa-list@matronics.com
> Subject: Europa-List: Manifold pressure gauge
>
>
> Hi, just received the Dec 2004 issue of the Europa Flyer.
>
> I am very interested to see that Brian Allsop managed to get his Kremen
> CS/VP prop approved without a manifold pressure gauge.
>
> When I put my Airmaster on my aircraft at the initial build I saw that
> Airmaster and Rotax did not require a MAP and so built my panel
> accordingly.
>
> When it came to the Permit to Test Fly Donaldson INSISTED on the fitting
> of
> a MAP. I argued that there was no requirement from the manufacturer of
> either bit of kit. He insisted. Sending me a copy of some JAR "minimum
> equipment" list which showed that a MAP was required for a CS prop.
> Probably
> written in 1948 !
>
> Anyway he is the king of this stuff and I had no option but to fit it
> (spitting !) on a sub-panel that destroyed the looks of my panel.
>
> Actually it is very useful for setting power.
>
> So how come Brian didn't need one ? It is only required for CS props -
> not
> VP props.
>
> I am interested about the description of VP and CS in the article. The
> Airmaster gives a VP option just as an aside. I have not used it yet.
> The
> Airmaster controller has switched positions for Take-Off (5700 rpm)
> Climb
> (5400) and Cruise (5000) plus a position where you can set any rpm you
> want.
>
> The Kremen seems to be a mixture of CS and VP almost as separate
> functions,
> when really the CS could be used all the time if all the required
> features
> are there.
>
> Unless someone disagrees !
>
> :-)
>
> Richard
>
>
>
>
>
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