I know this is off-topic, but has anyone measured or have a good idea
of the maximum temps expected inside the cowl?

I'm considering using thermal fuses as fire indicators inside my
cowling.  This is important in a pusher, since you  can't see the
engine compartment.  These inexpensive solid state thermal fuses open
at various temps.

Knowing what our usual water and oil temps should be, as well as
exhaust temps, I wonder how hot a cowl should get at a maximum, before
a fire is probable.  130 C?  150 C?  A composite cowl will be a
limitation, too, as they may degrade at temps in this range.

Scott Gettings

My guess is at least 150 F and maybe more under hot soak conditions.
It all depends on the rad location and how well the cowl is vented.
In the case of the glass goose you should be able to vent the cowl
well without adding a lot of drag. Where is the rad going?

Paul Lamar

Thanks Paul.  I'm planning on a tilted, large x thin radiator in front
of the engine (a pusher for those not familiar), served by a  K&W
intake duct, and possibly an exit diffuser if the radiator is far
enough ahead of the engine.  This won't be finalized till the engine is
mounted (too many variables).  I'll submit sample drawings then.  More
than likely I'll be making a custom cowling, so I can optimize some of
the component placements without having to worry too much about the
cowl dimensions.

With such an arrangement, I can place thermal fuses both ahead and
behind the radiator.  I'm planning on using two fuses in parallel in
each target location, to assure that a warning light is a true
temperature, not just a failed component.  I can easily instrument at 4
or more locations in the cowl.

Sounds like 100 C might be about right.  I just  don't want them to
blow from normal heat conditions.

Scott Gettings


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