Mailing List flyrotary@lancaironline.net Message #39579
From: George Lendich <lendich@optusnet.com.au>
Subject: Re: [FlyRotary] Carbs
Date: Wed, 26 Sep 2007 10:02:39 +1000
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Oops tying too quick again - Carbs not Crabs!!

Ed and Bill,
Just some ponderings as I progress along my way of understanding different carb developments.
 
I notice with a slide carb ( round on round opening) you get  more of a straight line function of air to fuel ratio as it progressively opens.
With a flat slide on round opening you get 'diminishing returns' ( my term) as you get past half way.
 
I notice that some carbs have eggs shaped openings, I guess that's to even out the percentage of fuel/air mix to percentage of opening and to compensate for the enrichening at higher RPM i.e. more air to fuel at higher rpm at the fatter end (top).
 
I was wondering what was wrong with a square carb - not completely square mind you, but with some roundness to corners say 1/2 diameter.
Wouldn't this provide for a more linier opening to fuel/ air ratio mix OR does this pose other problems such as air flow and drag/ turbulence? 
 
George (down under)


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