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I spent the afternoon at the cold and windy airport. There must have been some
50 mph gusts, typical New Mexico spring. Temp in the hanger was a little over
50 F.
But here's what you're interested in. I put Rusty's Davies-Craig pump on the
same setup I've been using to measure flow on the Meziere pumps. It's
difficult to keep everything the same because each pump has a unique input/
output configuration. All pumps were tested with aproximately the same input
hose size, and output hose size. The lengths varied by what I had available,
and adaptors were fabricated to match to the pumps. The hose from the water
container to the flow meter was 3/4 inch for all. The hose from the flow
meter to the pump was 1 inch for the D-C and WP337, and 3/4 inch for the WP136.
This hose was shorter for the D-C test. Output from the pump to the container
was 1 inch for the D-C, two 0.69 inch for the WP337, and 3/4 inch for the WP136.
First attachment is a photo of the test setup for the D-C pump.
Second attachment is a photo comparing the D-C and WP337 pumps. The D-C pump is
quite a bit smaller, and lighter. Third is the plot comparing the D-C, WP337, and the one data point I have for
the WP136.
The tiny D-C pump outperforms the WP136. I believe both of these pumps have
the same flow rating from the manufacturer of 20 GPM. The D-C pump is probably
benefiting from larger hoses, however it has a _much_ lower current draw.
The WP337, rated at 55 GPM, does a little better but with a much higer current
draw than the D-C.
I did note one difference. The D-C motor seemed fairly warm, so I put a
Thermocouple on it. Running at 14 V, the motor temperature was 138 F with OAT
in the low 50's. I didn't measure the temperature of the WP337 because I hadn't
noticed it being particullarly warm.
My conclusion is that the Davies-Craig pump outperforms the Meziere pump, but
the Meziere pumps appear to me to be of higher quality. The thing that
concerns me the most is the small size of the motor and it's high operating
temprature. I will check the WP337 running temperature after it's installed.
Even though the WP337 is consuming more power, it has quite a bit more mass to
dissipate the power in. That isn't to say I think the D-C won't last, as we
have examples in use, just that the Meziere pumps seems more robust. Another
thought, the Meziere pump may heat up to the coolant temperature when in
operation because of the conductivity of the aluminum. The D-C pump motor is
isoltated from the impeller by an air gap.
I don't believe I have enough data to determine what the WP337 flow rate will
be when installed. I need to know the static head pressure to estimate that. I
will just measure the flow when I get it in the plane. I'm sure it won't be as
much as I wanted. :)
Another interesting thing to do is look at this data compared to the data Todd
has previously reported. Todd's measurements were at 12 V, so comparing with
my measurement:
My Flow: 12 V, 4.8 A, flow 10.9 GPM
Todd's Flow: 12 V, 4.3A, flow 9.3 GPM thru engine and parallel Ford Evap cores.
Todd has larger hoses, so it seems my test setup is almost as restrictive as
his entire cooling system.
Bob W.
--
http://www.bob-white.com
N93BD - Rotary Powered BD-4 (real soon)
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