Here is a graph on some aircraft oil coolers from Aero Classic.
The non certified versions are cheaper.
Ask for Skid at Pacific Oil Cooler (800) 866 7332
These have the same claimed performance as Stewart Warner A/C units.
Here too is a chart of dynamic pressure so you can get
an idea how these coolers will work at what speed.
A well designed bell shaped duct should recover 80% of this
pressure.
If you have a 12" by 2" opening or 24 square inches
you should be getting about 12 cubic feet of air per second at
147 feet per second or about 100 MPH going in the duct opening.
That would be .937 pounds per second or 56 pound of air a minute
at an air density of .07651 pounds of air per cubic foot. Perhaps
a bit less as the duct is never 100% efficient.
The chart on the right is a nine plate unit but
for you 3 rotor guys this might not be enough.
Stewart Warner sell a 17 row unit that is 8.14" by 8.59" by 3.62"
thick. Weight without oil is 3.46 pounds.
SW part number is 10614A and Niagara is part number
20008A.
As far as BTU/min is concerned one BTU/sec is 1055 watts.
One BTU/min is therefore 63,300 watts I think.
One HP is 746 watts and a three rotor at full power of
300 HP will be putting about 100 HP or 74,600 watts
of waste heat into the oil cooler. Maybe a bit less.
Kind of fantastic claims for these coolers
as at 5 inches of water the way I see it at a 125 degree F
temp difference the chart claims 175 BTU/min or
11,075,500 watts!! or 14,849 HP! Sounds way too high.
Could be a decimal point off here and there.
Must be my arithmetic. Maybe my conversion factor is wrong.
Something is not adding up.
Can anybody help me out here?
MPH PSI INCHES H20
99.8 0.18 4.8
102.6 0.19 5.1
105.2 0.20 5.3
107.8 0.21 5.6
110.4 0.22 5.9
112.9 0.23 6.1
115.3 0.24 6.4
117.7 0.25 6.7
120.0 0.26 6.9
122.3 0.27 7.2
124.5 0.28 7.5
126.7 0.29 7.7
128.9 0.30 8.0
131.0 0.31 8.3
133.1 0.32 8.5
135.2 0.33 8.8
137.2 0.34 9.1
139.2 0.35 9.3
141.2 0.36 9.6
143.2 0.37 9.9
145.1 0.38 10.1
147.0 0.39 10.4
148.8 0.40 10.7
150.7 0.41 10.9
152.5 0.42 11.2
154.3 0.43 11.5
156.1 0.44 11.7
157.9 0.45 12.0
159.6 0.46 12.3
161.3 0.47 12.5
163.0 0.48 12.8
164.7 0.49 13.1
166.4 0.50 13.3
168.1 0.51 13.6
169.7 0.52 13.9
171.3 0.53 14.1
172.9 0.54 14.4
174.5 0.55 14.7
176.1 0.56 14.9
177.7 0.57 15.2
179.2 0.58 15.5
180.8 0.59 15.7
182.3 0.60 16.0
183.8 0.61 16.3
185.3 0.62 16.5
186.8 0.63 16.8
188.3 0.64 17.1
189.7 0.65 17.3
191.2 0.66 17.6
192.6 0.67 17.9
194.1 0.68 18.1
195.5 0.69 18.4
196.9 0.70 18.7
198.3 0.71 18.9
199.7 0.72 19.2
201.1 0.73 19.5
Paul Lamar
The AirCraft Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/ http://www.linux.org
