Constant Speed Prop Help

[Tjay]

Thanks for that Hitech. I thought I would just try and help out any peeps who were confused as to what prop pitch did and why you needed to alter it. So I deliberately avoided the mechanical details in case it all got a bit longwinded.

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Tjay of the Kraits. All my enemies die laughing.

[-blk--]

  Sorry HT, gotta correct you just a tad <don't kill me>.  The prop governor (and that's what it is, works just like the ball governor on a steam engine) isn't mounted to the prop.  The weights you see on say, a T-6 are there to help drive the prop to high pitch (because oil pressure is used to drive prop to low pitch..thus when engine quits the prop automatically moves to a high pitch).  The prop governor is mounted on the engine (usually to the Accessory Section), and is driven by some accessory drive shaft.

blk

PS-no all the WW2 A/C didn't use the same props, but they were all basically the same.  They all use oil pressure to either drive the prop into high or low pitch (depends on ths situation), they all have prop governors...  Except those Curtiss Electric props, but they all work the same way (push prop lever forward, engine speeds up, pull it back, engine slows down)...

[bod]

I know that the 109 G-10 had an electrically operated constant speed prop.

Bod

[hitech]

Thanks blk never new about the added weights on the T6 is this a common feature on us aircraft?

HiTech

[Lugnut]

what this all points to IMO is the need to include some kind of explanation ofs CSPs in the help section at some point down the road.

Lugnut

[-blk--]

  HT, it's common on lots of aircraft.  Basically, multi-engine aircraft all use them (because that way the prop starts to feather automatically when oil pressure is lost).

  The reason you don't see those weights on engines of, say, DC-3, T-28, P-47...  Is that those all use Hydromatic propellors.  But take a look under the spinner of pretty much any twin out there (Aztec, Duchess, Titan, Seminole, Seneca...), and you'll see them.  They're also pretty common on the regional turboprops (for the same reason).

blk

PS-it's a common feature on foreign aircraft as well

[Deadman]

Ok i think i understand a lot better now about how this works but I actually think the game needs to be revised so that the gauge doesnt show rpm but prop pitch settings
that would seem more accurate and get away from the illusion that we are seeing engine rpm here when actually we are not.  If you pushed the minus key it would move the prop pitch to increased pitch and if you pushed the plus key it would move to prop to a decreased pitch setting. (now if the game would model the sound of the prop biting more air when it was set to higher pitch settings this would be awesome)
I went to the web site mentioned in above posts and now this prop mixture and manifold pressure are a lot more clearer in my mind.
Check it out for your self and see if it doesnt clear it up for you as well.


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Tonight, it ain't right
I got to have me a week.
But I'll be back for you jack and I'll let the machine speak!  Thats right Thats right (Maniac Mechanic ZZTop)

[This message has been edited by Deadman (edited 10-07-1999).]

[indian]

Deadman the indication are correct straight out of the book on props. The only way these older props were constant speed was to set the rpms of the engine which is what we are doing. by running up the manifold pressure we are really increase torque, but according to the book the rpms should rise wiht increase minifold pressure. I dont want to put the hole chapter on the board but it is indicated right in the game. Some of the older planes used springs to hold the prop at a certain pitch some default to a set pitch that still can produce thrust after all something is better than nothing. The book is from my A&P class its called Aircraft propellersand Controls.

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Tommy (INDIAN) Toon

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[chisel]

Just to throw a wrench into the works for dedmans sake the Germans used prop pitch gauges. Basically looked like a clock. They set the pitch to this gauge for takeoff, climb etc. rather than RPM. They had a tachometer as well.

Different method same result

http://   [url=http://members.aol.com/bf109gust/index.html]http://members.aol.com/bf109gust/index.html[/url][/url]  

Go here for a look. Under construction details, cockpit


[This message has been edited by chisel (edited 10-07-1999).]

[This message has been edited by chisel (edited 10-07-1999).]

[Deadman]

Yeah tommy I understand what your saying but
the govenor can only adjust the prop to the limits of its stops and at engine idle the guage in a real airplane wouldnt be stuck on 3000 rpm.
but you could have the prop to min pitch even tho the gov wouldnt be able to produce this rpm till the throttle was moved forward. Either the guage needs to be mapped to actual eng rpm or it needs re labeled as a prop pitch setting which to my way of seeing it work is what it's actually indicating at this point.
maybe instead of seeing a guage we could have a little lever that moved back and forth with the plus and minus keys to represent the pitch control.
Hmmm I wonder if we'll get feathering capability on the twins?

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Tonight, it ain't right
I got to have me a week.
But I'll be back for you jack and I'll let the machine speak!  Thats right Thats right (Maniac Mechanic ZZTop)

[bod]

I think only the dials are implemented at this stage since neither the rpm or the manifold pressure are working correct.

The manifold pressure should also change when rpm changes for a set throttle position, and clearly it does not right now.

With regard to german planes i think all of them (at least late war) had some sort of automatic engine management. I think that was one of the reasons the Black 6 crashed a couple of years ago, when the pilot smelled "burned oil" and the engine started "running rougher". It was only the automatic engine management doing its job, but the somewhat unexperienced pilot  thought something was seriously wrong, and did a terrible engine-off landing.

Bod