MAN&RPM

[olds442]

ok in 3D modled planes theres two levers that move(singel motor plane such as a P51) ones bigger than the other
one controls MAN presser   and the other RPM.now RPM is is how fast the prop is moving MAN is the presser on the manifold how do you change manifold presser without changing RPM.prop pitch????? pls help just want to leran this game

[Oldman731]

ok in 3D modled planes theres two levers that move(singel motor plane such as a P51) ones bigger than the other
one controls MAN presser   and the other RPM.now RPM is is how fast the prop is moving MAN is the presser on the manifold how do you change manifold presser without changing RPM.prop pitch????? pls help just want to leran this game

Manifold pressure is what most people think of as throttle.  Prop pitch setting (RPM) is a cruise speed function that lets you save gas by making the propeller take a bigger bite out of the air while you reduce the throttle (MAP, remember?).  For all practical purposes in this game, you want RPM at max setting and adjust your speed with the throttle.  If you're in one of the main arenas, where saving gas is important, and you know you're going to just motor along for awhile until you hit the combat zone, go to the E6B function on your menu, check the cruise settings for MAP and RPM, adjust them and save gas (you can see how much you save in the E6B menu).

- oldman

[olds442]

thank you verey much for clering this up

A BIG :salute

[ozrocker]

Manifold pressure is changed by using the + - keys(default) on numbers pad.

                                                                       <S> Oz
                                         

                                         

[olds442]

Manifold pressure is changed by using the + - keys(default) on numbers pad.

                                                                       <S> Oz
                                         

                                         

I KNOW THIS i was trying to figer out prop pitch

[BaldEagl]

If you find yourself a glider and the engine isn't frozen reduce RPM to minimum.  That allows the prop to windmill freely and greatly increases your glide distance.

[olds442]

what about fixed prop planes

[Big Rat]

Easiest way to think of it is a manual transmission car.  What gear you are in will determine what rpm at what speed.  Manifold pressure, is an indication of engine load or how much you open the throttle on a car.  So between the two variables you can have all sorts of rpm (gear) and manifold pressures (throttle %) combinations.  Obviously this is simplified in a car since most don't have various turbo and supercharger settings that we can change while driving, but for the basic concept it works.

 
BigRat   

[olds442]

Easiest way to think of it is a manual transmission car.  What gear you are in will determine what rpm at what speed.  Manifold pressure, is an indication of engine load or how much you open the throttle on a car.  So between the two variables you can have all sorts of rpm (gear) and manifold pressures (throttle %) combinations.  Obviously this is simplified in a car since most don't have various turbo and supercharger settings that we can change while driving, but for the basic concept it works.

 
BigRat   

i ahve one guys saying i changes prop picth you saying its just fuel thing

[Big Rat]

i ahve one guys saying i changes prop picth you saying its just fuel thing

Actually we are saying the same thing.  Prop pitch = transmission gear ratio, in my example and Manifold pressure is equal to Throttle % in my example.  We are saying the same thing, I was just trying to put it into an example of something most can relate more closely to.  I actually own a pretty good example that I can use.  I own a supercharged manual transmission corvette.  Lets say I'm cruising in 4th gear at 2000 rpm manifold pressure is 10" of vacuum.  I run across somebody I want to pass but I'm not in a hurry so I leave it in 4th gear.  I increase my throttle % which increases my manifold pressure to 2 psi.  Obviously while accellerating in gear my rpm's will increase with speed.  If I wanted to maintain the 2000 rpm I'd have to upshift (change prop pitch) to 5th gear to drop the rpm back down.  Most cars don't have a constantly variable gear ratio so I can't maintain an exact RPM at a changing load in my car, I can try and keep it close by changing gears.  Same basic idea for max power and max cruise, at max power I want as much boost as I can get (7.5 psi in my case), at maximum power rpm (6250 in my case).  Max cruise I want as much vacuum (least manifold pressure) as I can get at as low an rpm that the engine combination will allow.  Hope that clears it up.

 
BigRat

[dud]

Maybe a CFI would be best to answer. Someone rated for a vari-prop model or even perhaps a old warbird. I remember trying to get a F14 rated combat jock try to explain a Cessna...didn't work out well. Where's CPT Dell? hehe 

[Oldman731]

Maybe a CFI would be best to answer. Someone rated for a vari-prop model or even perhaps a old warbird. I remember trying to get a F14 rated combat jock try to explain a Cessna...didn't work out well. Where's CPT Dell? hehe 

I...uh...I have a high performance endorsement and am part-owner of a Piper Saratoga turbo...

- oldman

[Dichotomy]

Um Dud...

Old and BigRat know what they are talking about.  When they speak I listen.  I'd advise you to do the same.

[dud]

Cha Ching! Then perhaps you can explain. ACP know's a crap ton of info about flight, help a aeronautical engineer in training out.  

I never meant to degrade anyones answer.

Oh and by the way,  a lil info about yourself may help in your sig. I have no idea that OldMan  has a HP endorsement...is he also a CFI? Dichotomy you can STFU since you are "just returning".

[olds442]

ok dose every plane in AH have a prop that can change picth