Engine RPM Question

[mussie]

Just wanted to clarify the RPM in AH

When we change our RPM we area actually changing the engine torque.... or to be more precise we are changing the Blade Pitch which therefore changes the torque the engine must over come to keep the blade spinning...

Is this correct ?

[Shaky]

The RPM setting on complex aircraft does adjust the propeller pitch. Its just easier to measure it as RPM, both in sensing and in a more exact display.

Manifold pressure adjusts engine power.

For you pilots that hold a complex ticket (not me, SEAL only) your hands are on the throttle, not the pitch during approach, right?

[Golfer]

when approach to land in an airplane with a constant speed propeller your hands are on the control yoke/stick and the throttle.  The prop should be brought full forward, which is "High RPM" or "low pitch" in order to produce maximum power in the event a go-around is required.

Leave the word torque alone in this one...

When you adjust the propeller control you're simply adjusting the size of the bite of air the propeller is taking.  This has a few effects which include good climb rate due to high rpm on takeoff, good cruise efficiency because of the larger bites of air the prop is capable of and reduced noise because the prop is spinning at a lower speed which means the prop tips are slower also thus creating less noise.

[mussie]

So when we adjust our RPM in AH we are adjusting the prop pitch correct ?

[Golfer]

Yulp.

[Alky]

It sure saves an amazing amount of fuel just by dropping the rpm's a little... great for those long rtb's when you're low on fuel

[hitech]

Mussie: You cant directly say you are affecting prop pitch, both rpm control and throttle control change the prop pitch. And niether is dirctly linked to the prop pitch.

There is a govoner on the engine that changes the prop pitch to maintain a preset rpm.

Increasing throttle, gives more torque hence speeding up the prop, and hence the govoner increases the prop pitch to slow the prop back to the preset rpm

All the RPM lever does is change the setting on the govoner.

HiTech

[mussie]

Thanks Golfer Shakey and Hitech

I appreciate the answers

Gonna foward this to my mate (I was telling him about AH and we got onto the RPM thing) he might just sign up for a try....

Later All