Today's Message Index:
----------------------
1. 10:30 AM - Re: NACA cockpit cooling vents (Frazier, Vincent A)
2. 08:06 PM - Re: Re: NACA cockpit cooling vents (James Baldwin)
Message 1
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| Subject: | Re: NACA cockpit cooling vents |
Cc: <jamesbaldwin@dc.rr.com>
--> Rocket-List message posted by: "Frazier, Vincent A" <VFrazier@usi.edu>
James,
Yesterday when it was 32 degrees outside (on the ground), the front NACA
inlet was providing relatively warm air. My OAT probe happens to be in
the front inlet and read 56 degrees at 3500' As you can see,
something doesn't add up since I should have been getting about 30
degree (or less) air coming in those inlets.
I don't have a temp gauge in the rear seat vent path, but I did put my
hand in front of the eyeball airstream and it was freezing cold, and
certainly NOT the 56 degree air that I had coming out of the front NACA
vent.
I don't have an explanation for why it does it, but it's not from the
sun warming the side of the fuselage.
All I can say for certain is that I will not put my next airplane's NACA
vents on the side of the fuselage.
When the wx gets warmer, I'll figure this out and post any findings.
If you don't know about air spilling back out of an inlet then study the
early P-80 jet intake structure. The gills were a fix to prevent
exactly what we're talking about.
Vince
*************************************
SNIP
Not sure I actually believe the temps on Vince's machine are REALLY
different without an actual measurement, but also not sure what either
of you mean by "air spilling out of the inlets." Surely you don't mean
the pressure side of the cowl inlets where it has been noted that vented
air tapped from the rear baffle provides a cool source. Please
enlighten me as I have no machine to go fly yet. Skin surfaces exposed
to sunlight might add energy in comparison to a source underneath the
airplane. I doubt any energy difference at these speeds due to
compressibility in a low pressure inlet, a.k.a. a NACA duct. I sure
would like to know the numerical values of the air temp coming out of
the two sources. I don't want to cut holes in the wrong place. JBB
SNIP
Message 2
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| Subject: | Re: NACA cockpit cooling vents |
--> Rocket-List message posted by: James Baldwin <jamesbaldwin@dc.rr.com>
Vince -
Good temp "data." That's close enough for me, and I'm not sure why you
are seeing warm air from the front vent location either. Obviously a
logical place to put the vent, too bad it doesn't work.
My comment on "air spilling" was in regard to at least one
installation I know of where the vent source is from the rear baffle of
the pressure side of the cowl inlet. No complaints of outlet
temperature and you would think the air would be warmed as it passed by
the cylinder fins.
At the least, I know where I won't put my vents. JBB
Frazier, Vincent A wrote:
>--> Rocket-List message posted by: "Frazier, Vincent A" <VFrazier@usi.edu>
>
>James,
>
>Yesterday when it was 32 degrees outside (on the ground), the front NACA
>inlet was providing relatively warm air. My OAT probe happens to be in
>the front inlet and read 56 degrees at 3500' As you can see,
>something doesn't add up since I should have been getting about 30
>degree (or less) air coming in those inlets.
>
>I don't have a temp gauge in the rear seat vent path, but I did put my
>hand in front of the eyeball airstream and it was freezing cold, and
>certainly NOT the 56 degree air that I had coming out of the front NACA
>vent.
>
>I don't have an explanation for why it does it, but it's not from the
>sun warming the side of the fuselage.
>
>All I can say for certain is that I will not put my next airplane's NACA
>vents on the side of the fuselage.
>
>When the wx gets warmer, I'll figure this out and post any findings.
>
>If you don't know about air spilling back out of an inlet then study the
>early P-80 jet intake structure. The gills were a fix to prevent
>exactly what we're talking about.
>
>Vince
>*************************************
>SNIP
>Not sure I actually believe the temps on Vince's machine are REALLY
>different without an actual measurement, but also not sure what either
>of you mean by "air spilling out of the inlets." Surely you don't mean
>the pressure side of the cowl inlets where it has been noted that vented
>air tapped from the rear baffle provides a cool source. Please
>enlighten me as I have no machine to go fly yet. Skin surfaces exposed
>to sunlight might add energy in comparison to a source underneath the
>airplane. I doubt any energy difference at these speeds due to
>compressibility in a low pressure inlet, a.k.a. a NACA duct. I sure
>would like to know the numerical values of the air temp coming out of
>the two sources. I don't want to cut holes in the wrong place. JBB
>SNIP
>
>
>
>
>
>
>
>
>
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