<<If your oil
temp doesn't increase when you have the flap closed, I suspect that
there is still plenty of air going through the radiator.
>>
Except on a winter's day, when (on many more open installations) an oil
cooler is not needed at all.
Duncan Mcf.
----- Original Message -----
From: "Frans Veldman" <frans@paardnatuurlijk.nl>
Sent: Friday, December 18, 2009 8:31 AM
Subject: Re: Europa-List: Europa Cooling - Rotax 914.
>
> <frans@paardnatuurlijk.nl>
>
> Mike Parkin wrote:
>> However, when airborne, the effect of the
>> door is surprisingly minimal. In the cruise at 130kts, with the flap
>> open
>> the temperatures are as usual sub 100 degs - 60 to 70 degs maybe. With
>> the
>> duct closed, the temperatures (water, oil, CHT) are only raised by about
>> 10
>> degs. One advantage is it makes my cabin heater a little more effective.
>
> Keep in mind that the maximum opening for optimal airflow is about 1/3rd
> of the radiator surface. Air won't be able to rush with 100kts through
> the radiators, so you need to compress the air after the radiators to
> let it exit with the same speed as the surrounding air. Any opening more
> than 1/3rd of the radiator surface is not going to have much effect at
> all.
> When the flap is "closed", how much exit area do you still have? Mind
> you that even small openings can have quite a large effect.
> Although you have ram air cooling for the cylinders, I don't believe you
> can cool the oil substantially without using the radiator. If your oil
> temp doesn't increase when you have the flap closed, I suspect that
> there is still plenty of air going through the radiator.
>
> Frans
>
>
>
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