Constant speed prop.?

Question

I've seen them on aircraft but I have no idea how they work or why aircraft have them. Are they the same as a variable pitch prop?

Answer 1

The constant is not the prop RPM.  By varying the angle of the prop the speed of the AIR passing through them can be made constant.

Good Luck...

Answer 2

A constant speed propeller is one type of variable pitch prop and it uses a combination of counter-weights and oil pressure to automatically change blade angle (pitch) in order to maintain a chosen RPM as aerodynamic loads change. The rpm is set with a propeller control in the cockpit. Another type of variable pitch prop, known as a controllable propeller, requires the pilot to manually alter blade angle in order to maintain a given rpm. This type of propeller requires constant fiddling by the pilot, it is very uncommon and is usually only found on antique planes.

Very basically, as an airplane pitches up or down for climb or descent, or it encounters changes in the air it is going through (updrafts, downdrafts, turbulence, etc), the changing air loads on the propeller blades cause the engine to speed up or slow down, much as a car engine does when you go up and down hills. Being able to change propeller rpm is analogous to being able to change gears in a car. Since an airplane engine operates most efficiently within a fairly narrow range of rpm, a constant speed propeller helps it do that automatically without continuous input from the pilot, so in a sense it is like an automatic transmission. Likewise, the controllable propeller described above is like having a manual transmission.

With a fixed-pitch propeller, it is like having a one-speed transmission and the only thing a pilot can do is increase or decrease engine power in order to maintain the desired engine rpm, which is not particularly efficient. However, variable pitch propellers are complex, expensive, and heavy, so many smaller airplanes do not use them. All multi-engine airplanes and most of the more powerful single-engine airplanes that are propeller driven employ constant speed propellers.

There's a lot more to it than that, but there you are in a nutshell.

Answer 3

they're more efficient then a fixed pitch prop and they offer reverse thrust

Answer 4

The Constant speed propellers, as the name signifies, are run at a constant  speed, the power/performance required is obtained by changing the pitch of the propellers. In their time, thay kept things simple by eliminating the mechanism of speed adjustment by opening/closing of throttles.

Variable pitch propellers can be operated from idle to full power (RPM is adjustable) while the pitch can be varied to suit the flight operating conditions, from fine to coarse to feather.

Answer 5

yes, a constant speed prop is variable pitch.