flyrotary@lancaironline.net Mailing List Archive

Just for a data point, In the 2003 Sun 100 I used about 3 gallons of water to cool the oil during the 28 minutes I was at full throttle. Flow rate was a bit excessive and it was not well distributed over the core so this number could be improved on. The oil was plenty cool though (~190 F during race on a warm day). Had a cooler day in 2004 so didn't need the water spray but turned it on during last 20 miles just to see the effect. Dropped oil temps about 25 - 30 degrees.

Tracy

On Wed, Jul 22, 2009 at 3:07 PM, Dennis Haverlah <clouduster@austin.rr.com> wrote:

I'm still contemplating installing a water spray for use during high power climb-out. I used Ed's cooling spread sheet and estimated I need about 200 Btu/minute additional oil cooling during climb.. I also calculated that 5 qts of oil need about 288 Btu to gain 40 deg. F during the first 2 minutes of take-off and climb This translates to about 150 Btu/ minute. I believe I need about 200 Btu/minute additional cooling to keep my oil cool on a 100 + deg. day.
The Latent Heat of Evaporation for water is 970 Btu/# or 8050 Btu/gal. For a 10 minute climb I'd need 200 Btu X 10 or 2000 Btu. This is approximately 1 Qt or 32 oz/10 minutes. My water flow rate would than be 3.2 oz/minute.

I found some "misting" spray nozzles at Home Depot and found they work well at 30 psi. I have a 12 V Schure RV water pump that can be used for initial testing.

Next week the afternoon temperatures will be above 100 deg again. I hope to get the water mister installed so I can try it.

If the medical water pumps David Leonard has will provide 30 psi or more I'd be interested in trying them.

Dennis Haverlah

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