Engine Speed Governing

Thanks RW,

It makes sense to me, in theory if not practise, that the prop could pretty much take over the operation of the Bing chokes.

There is another factor, load!

How does load influence the behaviour of the Bing, if only prop is being used to control its behaviour?😈

Sean

First, the choke has no bearing here, if it is off it is not functioning.  

Second, the butterfly allows the venturi to draw air and that depression is from the MAP created in the manifolds of the engine.  The slide has no mechanical connection to the butterfly (throttle cable system) 

When you load the engine, add pitch, it will change the manifold pressure.  The requirements are clear in that we want a given MAP for power at a given RPM, that part you can see in your spec sheets.  As an example if your not a boosted engine, say a ULS 100 HP engine, At WOT a correctly loaded (pitch) will give you a predictable MAP reading.  For example if I have a 29.92 standard pressure at the airfield and no boost then WOT at take off with a CS prop should read just below this number for being correctly pitched and we would be at 5800 RPM. 

 Generally this will be about 1 to 1.5 lower than the ambient at that field pressure.  As you climb the ambient pressure reduces and our MAP also will decrease.  The slide moves up in the venture as we loose MAP and the difference between the pressure inside the venturi is what draws the fuel from the float chamber into the venturi.  The float chamber is always vented to ambient air pressure that is higher than the manifold.  

Hope that makes sense for you. 

Cheers

Sean,

May I suggest you do your own testing on this?

You could then come up with best economy/ best balance between economy and cruise speed/best cruise speed settings etc. 

It would also be tailored to your aircraft combo, and after that, because I also have a Sonex, I could copy what you did:-)

This Forum is losing posts.

"...............that the prop could pretty much take over the operation of the Bing chokes."

I have no idea what this means or where the word "chokes" came from.

Can only speculate that somehow the computer put it in OR that I was so tired at the time of posting , failed to proof read.

I think I was trying to speculate that the prop could, in theory, control the MAP/fuel flow, without the need to use the butterfly valve (throttle)😈