REFLECTOR:Engine ram air

Rene Dugas reflector@tvbf.org
Tue, 28 Oct 2003 18:37:54 -0600


Thanks Jim,
It seems the point would be that we would need to know the velocity of
the air moving through the 3" opening in the controller.  That should be
calculable based on displacement and RPM's to get a volume per second.
I thought that at cruise one would want some slight pressure for ram air
based on the volume of air being drawn through this opening.  To much
pressure and the air just spills over the lip of the scoop and never
even enters the scoop.  Under non-ram arrangements this should be a
suction but if one can obtain a slight ram pressure at a little more
than would be sucked in at cruise of if desired at 25 squared then the
size of the opening could be determined.  I just don't know how.  The
pressure delivered to the scoop would depend on many factors but I would
think the main factor would be speed of the air and the extent one can
slow the high speed air down to get static pressure.  This may all be
wrong or too obvious to comment on but before I sleep at night my mind
wanders.
Rene'

PS   I built my scoop separate from the air box so it can be removed and
the filter removed from a 3 " flange mounting for the K&N.  The approx.
11" x 9" box has a side spring door flap to open in the case of scoop
obstruction allowing heated air from inside the cowl but still it would
be filtered.  No water problems and I do have a 3/16" hole in the most
dependent point of the scoop.

-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org] On
Behalf Of Jim Agnew
Sent: Wednesday, August 20, 2003 6:54 PM
To: reflector@tvbf.org
Subject: Re: REFLECTOR:Engine ram air

The air intake should not be less in square inches than the
area of the fuel controller intake.  If the controller
intake is 3" then the area is a little more than 7 Sq. In..

Jim

 
--- KeithHallsten <KeithHallsten@quiknet.com> wrote:
> Rene',
> 
> I have no particular expertise on this subject to share
> with you, but this month's Sport Aviation has an article
> on engine cooling that may have some principles you can
> put to work.
> 
> Keith
>  
>   ----- Original Message ----- 
>   From: Rene Dugas 
>   To: reflector@tvbf.org 
>   Sent: Wednesday, August 20, 2003 10:18 AM
>   Subject: REFLECTOR:Engine ram air
> 
> 
>   I've asked this before but did not get an answer.  I am
> no engineer either.  How big should the opening be on a
> ram air scoop feeding air to the engine on an IO 540 at
> 2300 rpm's?  I understand it is best to not have the
> scoop any bigger than necessary because of the overflow
> forms a slow mushroom of backed up air pushed ahead of
> the scoop.  Any takers?  Mine is about 2.5 by 2.75"
> expanding into an airbox with a K& N filter then into the
> 3 inch orifice under the engine.
> 
>   Rene'
> 


=====
James F. Agnew
Jim_Agnew_2@Yahoo.Com
Tampa, FL
Velocity 173 Elite Aircraft Completed
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