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Kevin,
A spray bar can be very effective as you are using the latent heat of
evaporator of water. If my calculations are correct, it takes approx
7773 BTU of heat to vaporize a gallon of water. So quite a bit of heat is
used.!
I calculate that if producing 160 HP at take off and taking 3 minutes to get
to 120MPH IAS where the airmass flow would handle the heat of 160HP, you
would need to get rid of approx 15,000BTU of heat (total over the 3
minutes - approx 5000 BTU/min) from the coolant radiators.
3 gallons of water (assuming it all evaporated- which of course, it would
not, as some would be blown through the core unevaporated - 50%? just don't
know) would provide 22,345 BTU of heat dissipation. So 3 gallons would
theoretically take care of your complete radiator cooling needs for the
first 4.5 minutes. But, since, your radiators would also be rejecting some
of the heat through the air mass flow (just not quite enough), the 3 gallons
(even if only 50% evaporated) would probably be quite a bit more than you
needed for one take off.
Then you would need to figure out the spray flow rate so you wouldn't be
spraying more water than the core heat could evaporate and therefore wasting
it. You would also need to figure out an adequate spray pattern, build/buy
the nozzles, water pump, water container, etc. But, certainly doable.
Tracy Crook at one time used one when he was being held on the ground for
extend periods and needed more cooling than airflow from prop was providing.
Don't know what the down side of continuos use might be. That's lot of
water vapor under the cowling, but most would of course blow out - however,
corrosion might be a consideration.
My $0.02 worth
Ed
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message -----
From: "kevin lane" <n3773@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Saturday, December 06, 2003 1:13 AM
Subject: [FlyRotary] spray bars
> in all this discussion about thick cores, since I am building a p-51 style
> 5" core myself for my -8, I wondered how effective a water spray bar would
> be for the few minutes of critical climbout airspeeds. how effective is a
> spray bar? it seems stupid to have a larger radiator to handle a very
small
> portion of the flight. would that much water need to be carried for a
> typical flight?
> Kevin Lane Portland, OR
> e-mail-> n3773@comcast.net
> web-> http://home.comcast.net/~n3773
> (browse w/ internet explorer)
> ----- Original Message -----
>
>
>
> >> Homepage: http://www.flyrotary.com/
> >> Archive: http://lancaironline.net/lists/flyrotary/List.html
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