Few questions on the Beechcraft...

[Oracle427]

Is this an electric prop by chance? I haven't read the manual as I don't own it yet.

[LZ-WIL]

Is this an electric prop by chance? I haven't read the manual as I don't own it yet.

Hi,

No, I believe it is a oil-spring constant speed propeller hub. When we cycle the prop, the oil pressure drops a bit.

Cheerz,
Vladimir

[cristi.neagu]

It should be normal for the prop to reach full rpm with 50% throttle. That's what the speed controller is there for, after all. It should be able to hold any commanded prop rpm in the green arc as long as MP is in the green arc.

[Piper_EEWL]

It should be normal for the prop to reach full rpm with 50% throttle. That's what the speed controller is there for, after all. It should be able to hold any commanded prop rpm in the green arc as long as MP is in the green arc.

I’m not sure but I don’t think that is the case with the C182T. I’ll have to check though.

[Piper_EEWL]

Ok I’ll revise what I said earlier. If you hold the Bonanza with the brakes and apply full throttle max rpm is reached at almost full throttle. But if you apply full throttle while the plane is already rolling it’ll reach full rpm earlier due to the forward speed of the plane. So I think it’s just a little bit of a different setup on the Bonanza then on the Cessna.

[ClipperLuna]

I think you're right, Piper; the Bonanza's just setup differently. I made a mental note when I was doing pattern work earlier today, and it looks like it's "programmed" to rev up to 2600--but no more than this--and hold it there for less than 3 seconds when you advance the throttle to full when rolling.

[AKar]

Regarding static RPM of CSP...

In general, constant speed propellers behave just like fixed pitch propellers. Usually they should not quite reach, or less exceed, the redline RPM and therefore should never 'start governing' when you run the engine against the brakes. The adjustment that sets up the static RPM is that of propeller low pitch stops, and is obviously not adjustable by pilot. The static RPM should usually be within some 100 RPM from the redline, and failure to reach that usually indicates that the engine is developing less horsepower than it is supposed to. The reason for the propeller limiting the engine RPM below the redline is precisely that of avoiding engine overspeed when the throttle is quickly applied. A bit of forward speed (or some moderate headwind) is enough to smoothly rise the RPM to the redline, to which the governor promptly reacts and starts to command increasing pitch as the RPM goes just a bit above redline.

Specifications of some installations allow for static RPM to be equal to the redline RPM. In such case you don't know for sure "from the books" whether it is the low pitch stop setting or the propeller governor that limits the RPM. Therefore, the adjustment is on less-solid basis, so to say. Generally speaking, if the RPM goes up to and transiently through the redline on application of full power against the brakes with wind from the side, without knowing better I'd call that a misadjusted propeller. Certainly the redline should not be reached at partial power.

When the propeller operates in constant speed range (that is, when the governor is governing...), it should never overspeed in steady state. Transients that exceed the redline are allowed, and manufacturers provide rather specific instructions on how much overspeed and for how long is allowed, and what needs to be done if exceeded.

This applies to GA piston engines. General aviation turboprops, and all kinds of legacy radials and warbirds etc. are entirely different stories.

-Esa