Just started flying the G36 and don’t understand the relationship between RPM and the manifold pressure. I have auto manifold set in the sim, but after over reving the engine and I back off a bit, the manifold pressure drops to near zero. What am i missing?
Thanks
That’s normal - to a point. With the engine off, the manifold pressure should match the barometer. Running at idle, the manifold is under a vacuum. As you open the throttle, more air goes in, reducing that vacuum, but it shouldn’t ever reach the same reading as the baro. Turbo mods will behave differently. At high throttle, you should see pressure above the baro (boost), but at idle, it would likely fall back to a vacuum, since there isn’t enough exhaust to spool up the turbo.
Doesn’t sound like realistic behaviour to me. What you are talking about (too high RPM) can’t be solved by backing off on the throttle, eventually it will when you reach the point where the engine isn’t producing enough power to drive the propeller and RPM will drop.
You’ll need to move the propeller speed lever back a bit, this lever controls propeller (and engine) RPM by changing the propeller blade angle. With it set full forward the propeller is in a fine blade angle which results in high RPM. Moving the propeller lever back commands the governor to maintain a lower propeller RPM by changing the blade angle to a coarse pitch.
The manifold pressure issue you are describing sounds like a bug, unless power is set really low (idle or close to) the MAP should not be close to zero. I don’t know what the auto-MAP in MSFS does but I’m assuming it keeps the MAP constant during climb and descent. Normally you’ll need to add power during climb and reduce during descent to maintain a constant MAP.
Thanks for the response. Should you put the prop into a course pitch for take off and thin it out for cruise and landing. I don’t know how to manage throttle prop and mixture, have to do some reading.
Thanks again
Just the opposite. Fine pitch is like first gear - you get the most leverage to accelerate from a stop. Coarse pitch is like 5th gear.
What TC is trying to say… when reducing power, reduce your MP first, then reduce prop rpm. If you do it in reverse, you could blow your engine up as putting it in course pitch (reducing RPM) actually puts a higher load on the pistons and could break them.
When wanting to increase power do it in reverse, increase prop rpm first, then increase MP.
If you’re not sure what settings to use for each - “match” them up in value (but you really should get a POH and see what the recommended values are for various phases of flight).
Still overspeed isn’t correct. I haven’t flown the G36 in MSFS but I did in real life. The prop governor should not allow overspeed.
Yes, mixture - prop - power when increasing power, power - prop - mixture when reducing.
You just said the reverse of what I said…
?
I’m saying the same thing right?
Bottomline is that the prop lever shall stay above the power lever to prevent overboost.
I guess my first post might be a little confusing, what I was trying to say was that propeller RPM cannot be controlled by the power lever, unless going really low on power to the point the prop is at the low pitch stop and power is reduced further. From this point onwards it basically becomes a constant speed prop.
It was late, I think adding the mixture in there was confusing me.
I pair that with Throttle/MP in my thought process more based on altitude than setting the other two…
But you ain’t wrong 