----- Original Message -----
Sent: Friday, December
18, 2009 5:24 PM
Subject: [FlyRotary] Re:
Radiator/Oil Cooler Combo
I think while there are lot of Nifty
looking gadgets out there, you need to keep in mind that what may work well for
a piston engine in cooling oil may not for the rotary. The basic reason
is the rotary dumps approx 1/3 of its total waste heat load (not counting
exhaust heat) through the oil. In fact, you can calculate the approx BTU
you must get rid of through the oil.
A 13B turning 6500 rpm with an 12.65 (best
power) air fuel ratio will be flowing approx 16.1 gallons per hour. This
equates to needing to get rid of approx 2650 BTU/MIN of waste heat
through the oil cooler. Now using the old heat transfer
equation Q = BTU, M = mass flow and Dt = temp difference, cp
(air = 0.25)
Q = M*Dt*cp and assuming
you heat up the air so that it exits 100 deg F hotter than it went into the
cooler, then solving for the air mass M required = Q/ Dt*cp = 2650
/100*0.25 = 106 lbms/min or 106 pounds of air per minute.
A cubic foot of air at sea level = approx
0.0765 lb/cubic foot. So to get 106 lbms/min you need to have 106/0.0765
= 1385 CFM of air flow through the oil
cooler. Now that is a sizeable amount of air required just for the oil
cooler at a modest power output of 160 HP.
My point, is that, before you go spending
your money and adding weight and complexity to your installation, sit down and
determine what each element will do for you and whether it is really worth the
money and weight.
My person opinion is that it is hard to
beat the efficiency of a well position oil cooler with adequate airflow through
it.
But, just my opinion. Certainly
there are cases where a small cooling assist might make the difference
and these things might make the difference. In some cases, space
precludes the idea solution and in that case oil/water heat exchangers and
other methods are called for.
But, if you are in the planning stages, my
suggestion is strive to get the right sized oil cooler positioned with good air
flow.
Ed
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of william singer
Sent: Friday, December 18, 2009
4:51 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re:
Radiator/Oil Cooler Combo
Modine makes such coolers. My Ford Thunderbirds (89
to95) have them. wiliam singer
----- Original Message -----
Sent: Friday, December
18, 2009 10:26 AM
Subject: [FlyRotary] Re: Radiator/Oil
Cooler Combo
Our 1992 Honda Accord EX Wagon has a oil
to water heat exchanger that is sandwiched between the oil filter and the
engine block. It is about 2” thick, the same diameter as the
filter, and mounts with a longer hollow stud than would be used to mount the
filter directly to the block. I have no idea of its capacity.
Steve Boese
-----Original Message-----
From: Rotary
motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Thomas Mann
Sent: Friday, December 18, 2009
9:03 AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Radiator/Oil
Cooler Combo
….does anyone know of an oil filter mount that includes a
heat exchanger?
T
Mann
__________ Information from ESET NOD32 Antivirus, version of virus signature
database 3267 (20080714) __________
The message was checked by ESET NOD32 Antivirus.
http://www.eset.com