Re: REFLECTOR: oil temp

[john daniel cowan <jdcowan@mail.telis.org>]

Alan, HOW/WHERE are you routing your cabin heat ducts and controls from a
wing root oil cooler? through the  ceiling fresh air duct? is that possible
(ok, reasonably easy?) through the keel? w/air exit ports blowing warm air
under the seats? where are you passing the ducted air? through the firewall
or wingroot? do your toes freeze if you just have a hot air vent in the back
of the cabin? (probably not a problem in 29Palms or south Florida but I may
be relocating further north in the fall).
 what prop are you using on your 173/300?  which type of cooling did you
use? (sounds like updraft baffling from your note)

On a fuel injected engine (IO-540-k for example) I've observed the high
pressure fuel lines to the injectors are placed in a 'spider' array on the
top of the engine, which is on the cool air side of the engine in a
downdraft arrangement
on a Piper. An updraft arrangement would probably lead to vapor lock problems
with hot starts. (Assuming that in a tractor aircraft the updraft cooling is
not used, due to oil discharge onto the windshield, which is not a concern
in pusher aircraft.)

another thought: Sport Aviation has published at least two articles showing
the computer generated air pressure/flow diagrams in artificial color
coding. With all the computer/brain power available in this group, does
anyone have the 
program they did this with and the lofting data for the Velocity
airframes/airfoils?  I'd love to see the high/low pressure areas on this
airframe at cruise and climb angles of attack. Whats more, I'd pay for a
poster size picture of the same.  My 100mhz email port computer would take a
year to run that program, so someone else willhave to do that for me.   It
would sure answer a lot of questions about the best areas to place vents,
oil cooler airflow exits, updraft louvers on the upper cowl(?), etc.

I'm assuming the opening in the front of the keel on my RG is going to blast
air through the keel into the cabin on takeoff and landings, when the nose
gear doors are open. (they'd best be open!) I haven't arrived at any
wintertime solution for this yet.  


At 04:18 PM 1/30/99 -0500, you wrote:
>
>
>Simon Aegerter wrote:
>
>> That makes sense only if the cooler is able to get rid of that heat. That
>> means it has to be large enough and there has to be ample air flow. It
>> seems that nobody has ever measured the airflow through our oil coolers.
>> The porting of the air duct may not be ideal. The out
>> port of the air duct may be too small and it may be in the wrong place.
>
>Yes it is.  The nose of the airplane is all positive in pressure.
>
>> Nobody seems to know. I don't. I intend to do some real measurements
>
>Do you want to borrow my manometer?
>
>> I have found that all measures that improved the
>> airflow through the bottom of the engine compartment lowered the oil
>> temperature more than anything I did to the oil cooler.
>
>This seems to be a good argument for up draft cooling.   But we don't want
to go
>back to that cooling system because we know it has worked for years.  Besides,
>heat doesn't rise does it?  It must fall for a plentum to work good!  High
>velocity air also likes to go through ducts with a lot of corners and ridges.
>Sorry for the sarcasm but this whole issue is....well I better not say any more
>of  what I think.
>
>For the bigger engines putting the oil cooler(s) to the outside of the TE wing
>root with slits for air to past straight through from high to low pressure
works
>great for engine cooling and cabin heat.  It also cuts down cooling drag
and is a
>separate system from the CHT cooling.  This and a prop with a lot of cusp
at the
>root is probably the only way to get the high powered (more heat) tight finned
>300's too cool enough to not have to step climb.
>
>Alan
>
>
>
>
>