----- Original Message -----

From: Bill Dube

Sent: Monday, April 19, 2004 4:47 PM

To: Rotary motors in aircraft

Subject: [FlyRotary] Re: water coolant percentages

 

If you dont need the high freeze protection, Id opt for corrosion inhibitors in a solution of maybe 25-30% e-g in water (for some increase in boiling point), and a pressure cap of 22-25 psig.

        As noted earlier, all airplanes need freeze protection. I was flying recently in Tampa at night and the temperature at 15,000 ft was something like -10 Celsius.

        Water will often freeze in the radiator if you do not have anti-freeze, even if the engine is warm. The freeze will start in a low flow (water) region and will then spread as the flow is further blocked, perhaps bursting radiator tubes as it progresses.
        

 

I suppose this might be possible at a low power setting and while using a thermostat.  The problem can be completely avoided if you use a cowl flap for temperature control instead of thermostat.  Restrict the airflow through the rad and the coolant stays hot.  Reduced cooling drag is a bonus too.

Tracy