Mailing List flyrotary@lancaironline.net Message #39532
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Re: [FlyRotary] Re: Area of a circle
Date: Sat, 22 Sep 2007 12:25:19 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
I agree with Al, George. 
 
However, if you wish to enjoy the thrill of calculating that area (which is not a trivial task), here is a document that has all the information (formulas) you need.
 
 
     Now if you are willing to assume that the throttle plate  thickness and its rod are not a factor (maybe not a bad real-world assumption just to get the area of the opening - but different story regarding its effect on air flow which is why Al's suggestion is a good one), I have attached a spreadsheet with this simplification of the math.
 
Ed
 
----- Original Message -----
From: Al Gietzen
Sent: Saturday, September 22, 2007 12:06 PM
Subject: [FlyRotary] Re: Area of a circle

George;

 

Determining the area of the opening of a circular butterfly with position is certainly complex enough; but the flow is likely not directly proportional because of the complexities of the flow characteristics and pressure changes.  I would think measuring it is really the only way.  Do you have access to a flow bench?

 

Sorry; probably not very helpful,

 

Al G

 

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of George Lendich
Sent: Friday, September 21, 2007 9:21 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Area of a circle

 

Chaps, 

I am trying to work out the area of carb inlet as it is opened incrementally.

 

This involves the overlapped portion of two circles, as well as, a circle cut into slices ( straight cuts).

 

This should give me an indication of the linier or otherwise, volume of air as it sweeps through the carb.

 

This then should indicate the shape of the grind of the needle in maintaining continuity of the mixture ratio of fuel to air.

 

Any helpers with this one!?

George (down under)

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