Hi Ed,

Al's number was .02 BTU/cu-ft. - F and your number is 0.241 BTU/lb - F.
Per the web site you mentioned, density is given as 0.08018 lb/cu-ft.
So if I'm doing the conversion in the right direction:
 0.241 X 0.08= 0.019 which is about 0.02.

Are both numbers correct?

Bob W.



On Fri, 21 Oct 2005 20:46:02 -0400
"Ed Anderson" <eanderson@carolina.rr.com> wrote:

> Al, I went back to some of my spreadsheets and I have for constant pressure (Cp) as
>
> 0.25 BTU/Lbm/F
>
> Here is web site which gives it as 0.241 BTU/LBM/F at 32F Sea Level
>
> http://www.uigi.com/physical_prop_e.html
>
> So looks like you have the decimal off a bit.
>
> Sorry, it took me so long, been out at the aircraft all day putting on the new right gear leg, and brakes, etc.
>
> Ed A
>
>
>
>
>   ----- Original Message -----
>   From: Al Gietzen
>   To: Rotary motors in aircraft
>   Sent: Friday, October 21, 2005 2:59 PM
>   Subject: [FlyRotary] specific heat of air
>
>
>   Ed, or Bill, or somebody; help me out here.  I was reviewing my calcs for air flow requirements, and find I used 0.02 Btu/cu. ft -F for the specific heat of air.  I don't know where that came from, and can only find it in joules/Kg - K.  By the time I do all the conversions to British units and mass to volume I now get quite a different number.
>
>
>
>   What is a good number for air at about 1 atmosphere and, say 90F; in Btu per cu ft per degree F?
>
>
>
>   Thanks,
>
>
>
>   Al
>


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