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Message-ID: <2e24f88d0706010711k3c13391cs4a6d0cceb647c2a3@mail.gmail.com>
Date: Fri, 1 Jun 2007 08:11:27 -0600
From: "Hans Conser" <hansconser@gmail.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Intake CFM air flow
In-Reply-To: <list-2078487@logan.com>
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References: <list-2078487@logan.com>

Don't forget the VE on  PP engine can be over 100%!

On 6/1/07, Ed Anderson <eanderson@carolina.rr.com> wrote:
> Remember that the 13B is supposedly an 80 CID engine.  In reality it acts
> like a 160 CID 4 cylinder 4 stroke or a 80 CID 2 stoke power-wise.  Now this
> is assuming a 100% Ve for induction efficiency, any restrictions and your
> air flow is, of course, less.
>
> So for a 160 CID 4 cylinder air flow CFM = CID*RPM/(2*1728) = 160 *6000
> /(2*1728) = 277.77 CFM
>
> Now if you can turn 7500 rpm (say with a Renesis and the 2.85 gear box) you
> would have
>
> Air Flow = 160 *7500 * (2*1728) =  347 CFM  and if in an automobile and
> winding to 9000 rpm you would get
>
> Air Flow = 160 * 9000 * (2 *1728) =  416 CFM but still short of an all-out
> V8 - sorry!  If you want more airflow then forced induction or  nitrous
> oxide injection is the only way I know got get that kind  power.  With
> nitrous oxide of course you don't need to increase the airflow because the
> nitrous oxide gas is providing the extra oxygen needed during the combustion
> process..
>
> Concerning air velocity through your throttle body
>
> For a 3" dia TB flowing 278 CFM here is what I get using my Excel
> Spreadsheet.
>
> Your TB area is pi*(dia/2)^2 = 7.068 sq inch = 7.068/144 = .049087 sq ft
>
> Flow rate = Velocity * Area = (ft/min)*(ft^2) = (ft^3/min), so solving for
> velocity = Flow Rate/Area
>
> Velocity = flow rate (ft^3/min)/Area (ft^2) = 277(ft^3/min)/(.049087(ft^2))
> = 5663.369 ft/min velocity through TB
>
> Converting to feet/sec = 5663.369(ft/min)/60(sec/min)  = 94.389 ft/sec
> converting that to MPH = 94.389(ft/sec)*3600(sec/hour) /5280(ft/mile)  =
> 64.35 Miles/hour MPH for air velocity through your TB at 6000 rpm.  I could
> have screwed up the math along the way, but that's what I get.
>
> So I get 64.35 mph air velocity through your 3 " TB - a rather stiff breeze
> {:>).  So its important to minimize pressure drops and drag in your inlet -
> but, keep in mind its just one part of  the total 3 component system  -
> induction/engine/exhaust - that determines your through put.  You can have
> the best inlet money and theory can buy, but if you engine and/or  exhaust
> can not support that flow, then you won't get it.
>
>
>
> Ed
>
>
>
> ----- Original Message -----
> From: "Bill Bradburry" <bbradburry@allvantage.com>
> To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
> Sent: Friday, June 01, 2007 8:16 AM
> Subject: [FlyRotary] Intake CFM air flow
>
>
> > Thanks Bob and Ed.
> >
> > I would appreciate the pictures, Bob.
> >
> > Ed, I expected a much higher flow.  I thought that it would be in the
> > neighborhood of 600-800 CFM!  I guess I have been spending too much time
> > reading the carburetor adds for V8s....
> > I think that the 278 CFM would translate to an air velocity of about 48.25
> > MPH going through my 3 inch throttle body.  That seems like a gentle
> > breeze!  Maybe I am spending too much time trying to remove restrictions
> > to the air flow in the inlet??  :<)
> >
> > Bill B
> >
> >
> >
> > Subject:
> > Re: [FlyRotary] Intake CFM air flow
> > From:
> > Bob White <rlwhite@comcast.net>
> > Date:
> > Thu, 31 May 2007 18:48:02 -0600
> >
> > Hi Bill,
> >
> > I built a can around it out of aluminum.  The can clamped on at the
> > same place as the filter and it was about 6" dia or maybe a little
> > larger.  I then made a fiberglass air inlet that sealed to the can with
> > a strip of red silicon engine baffle.  I was hoping to generate some
> > ram air pressure, but didn't get a chance to measure it to see how good
> > it worked.  I'll take some pictures next time I get to the airport.
> >
> > Bob W.
> >
> >
> >> Subject:
> >> Re: [FlyRotary] Intake CFM air flow
> >> From:
> >> "Ed Anderson" <eanderson@carolina.rr.com>
> >> Date:
> >> Thu, 31 May 2007 19:22:24 -0400
> >>
> >>
> >> Bill, at 6000 rpm the airflow is 277 CFM assuming 100% Ve.  Here is a
> >> formula
> >> for calculating airflow for the rotary.
> >>
> >> Air Flow (CFM) = (40 cubic inches per face)*2(number rotors) * 3(faces
> >> per rotor)*rpm of rotors(=  E shaft rpm/3) /1728 (conversion to CF) =
> >> 40*2*3 *(6000/3)/1728 = 240*2000/1728 = 277.77 CFM
> >>
> >> Or simplifying Air Flow (CFM) = 80*RPM/1728 = 277.77 CFM air flow at 6000
> >> rpm for a 2 rotor.
> >>
> >> Ed
> >
> > --
> > Homepage:  http://www.flyrotary.com/
> > Archive and UnSub:
> > http://mail.lancaironline.net:81/lists/flyrotary/List.html
>
>
> --
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