View Full Version : Prop Pich

04-01-2006, 11:28 PM
Can someone please explain Prop Pitch on both Constant speed and Variable Pitch propellers

And when to use Prop Pitch when flying

04-01-2006, 11:28 PM
Can someone please explain Prop Pitch on both Constant speed and Variable Pitch propellers

And when to use Prop Pitch when flying

04-02-2006, 05:03 AM
With a constant speed prop (which is the most common among planes ingame), what you're doing is setting the RPM.

So say for example you set the PP at 50%, the governor will do its damndest to keep the engine running at 50% RPM regardless of throttle setting by automatically varying the PP. As a general rule I tend to set the RPM the same as the throttle (eg 55% RPM, 55% throttle) but that's because I'm far too lazy to work out the best settings for each different plane.

With a variable pitch prop you're actually controlling the pitch of the prop directly (the angle at which it bites into the air). AFAIK the only aircraft ingame with VP props are the German fighters ( I'd be happy for someone to correct me on this though! http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif ). In the case of these planes though the system defaults in auto mode (German planes had a complex automatic system controlling prop pitch, fuel mixture, supercharger settings - all the pilot had to do was move the throttle). In a Bf109 if you put your prop pitch and throttle to 100% you'll overev and fry your engine in about three seconds.

When to use it: generally speaking, on takeoff, climb and combat you will want high power settings (90-110% throttle, 90-100% RPM)

When cruising you can use lower settings (50-75 throttle and RPM) to conserve fuel and keep your engine cool. Bear in mind the faster you cruise, the better you will be able to respond if you are 'bounced'. Don't plan on being bounced but expect it always.

On landing I always stick my RPM at 100%. Two reasons - firstly this provides a braking effect (at least I think it should - not sure if it's modelled) rather like the engine braking effect you get in first gear in a car. Secondly, if you fluff up your approach you want to be able to throttle up quickly to abort and make another run without fussing over RPM settings.

04-02-2006, 05:23 AM
Click here for quite a good article with diagrams (http://www.avweb.com/news/columns/182082-1.html) explaining the history of and difference between various types of propellor.

04-07-2006, 03:04 AM
Thanks for the help

04-07-2006, 10:14 AM
CSP in the sim, if you have the pitch/rpm set too high for the power you have, the plane
will drive the prop and either slow you down or keep you from going faster.

Try getting up to speed with pitch at 100 and then pull power to 30%.
Then try the same but lower pitch along with power.

It is good that with full pitch and low power you can lose speed and alt to approach landing.
Still too much then do S turns but be careful as you won't regain enerygy without increasing
power. 100% pitch keeps the engine at speed in case you have to abort, add power.

In a dive you no way have the power to drive the prop past full level speed. Drop the pitch
and the plane can go faster. The prop tips trace a spiral path through the air that if it
gets too long the tips will make shockwaves. The more times per second they turn, the longer
the path. FB series does have compression but not confirmed is prop compression, does not
mean it is not there. But if you do cut the pitch/rpm then you will be able to dive to
higher speed. Just don't start the cut till you are going fast.

Last of all take a P-51 at 90% power and 100% pitch at 1000m alt. Trim and retrim until it
is going as fast as it will. Now reduce pitch to 95%. Retrim to level, note the direction
you had to change trim and note your new speed. Try 90% pitch, same procedure.

This is part of Complex Engine Management.