Nigel Graham a crit :
> <nigel_graham@m-tecque.co.uk>
>
> The importance of the coolant system is certainly not lost on me.
> While you are probably not aware of it, I have done a lot of work to
> develop a fully ducted water/oil radiator with full diffuser, nozzle
> and cowl flap in an effort to reduce cooling drag and improve cooling
> efficiency.
Nigel,
Thank you for your message and your indications, and please pardon me
for the confusion about the original posters.
Congratulations on your cooling developments, in my opinion it is really
worth the effort. With our engine installation, we are able to choose
any running temp within the green arc in climb, cruise, descent.
> Your experimentation and the experience of coolant failure of others
> begs an interesting question, if the Rotax air cooled barrels do not
> offer any increased endurance in the event of coolant loss - why use
> air-cooled barrels?
> Water cooled barrels would offer far better heat distribution and thus
> less localised distortion and allow tighter tolerance pistons that in
> turn would develop greater power with less noise.
Here are some musings on the subject :
- Concerning the barrel temperatures, we must consider that the cooling
needs of the barrels are an order of magnitude less than those of the
heads, so liquid cooling is probably not worth the hassles.
- With separate cylinders and air-cooled barrels, there is no risk of
mixing oil and coolant in the event of a blown gasket like it sometimes
happens in automobiles.
- Also I noticed that the Rotax heads behave like "temperature wells"
that directly drive the barrel temperatures, so barrel cooling is
definitely not an issue as long as the heads are correctly cooled.
Best regards,
--
Gilles
http://contrails.free.fr
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