What happens when you adjust the power on a constant speed prop?

Question

When you adjust the pitch control, this controls the angle of the blade, and thus the RPM correct? So when adjusting the power control, what is happening? I know there is more power being generated, but for the plane to go faster, wouldn't this also change the blade angle? Because I thought that Pitch would control RPM and Blade angle.... Just need it layed out in simple terms. I fly constant speed, but can't wrap my brain around the concept.

Answer 1

When you are adjusting the power control, you are changing the manifold pressure, as you likely know.  Since more or less power is being produced by the engine, the speed at which the prop is capable of is changed.  

Lets say you increase the power. Your engine is now providing more power to the propeller.  The prop then wants to turn faster (as it would with a fixed pitch prop).  Since you have a constant speed prop, the blade angle will be changed to maintain the RPM.  That's what a constant speed prop does.  It changes blade angle to control the RPM, thereby maintaining a... constant speed.  The more course pitch allows for a faster cruise speed without changing the prop RPM.

Hope that helps.

Answer 2

In simple terms, the prop control is used to set the desired RPM. The propeller blade angle will be adjusted as much as necessary  to maintain that RPM. Therefore, if you leave the control alone and begin a climb or descent the blade angle automatically adjust itself to maintain RPM.

When adjusting the throttle, more or less power is generated and the blade angle is adjusted accordingly to maintain the RPM setting.

Rather than thinking of the prop control as setting a particular pitch, think of it as setting an RPM and the propeller adjusts itself to meet that speed.

Answer 3

Both good answers. Here's a tidbit more: Let's assume a level flight at cruise.

As you apply power (increase manifold pressure) that power tries to increase the prop RPM. As already explained, the prop governer will automatically increase the blade pitch so that the added drag on the prop from the bigger "bite" maintains the selected RPM.

The increase in power that you just selected with the throttle is reflected in the increased speed of the aircraft. The bigger bite that the prop takes moves the aircraft forward faster.