Jerry Hey wrote:

I heard a new phrase (to me) in connection to the 13-B.  It is

THERMAL RUNAWAY.

What it suggests is that there is an operating rpm and hp above which
cooling the 13-B becomes increasingly  much more difficult. Given the
space available for radiators in my Tailwind, this  sets the limit on
how much power I can hope to generate. Question:  Is 170 hp at 5500
rpm continuous a realistic goal? I have Tracy's ignition and fuel
injection.    Jerry

Not at all Jerry. 170 HP is well within reason and easy to achieve.
I think the term "thermal runaway" is misapplied to any internal

combustion

engine. Are you putting the rad in the aft fuselage?

Paul Lamar

Dale Smith wrote:

My $.02 worth ... the only time I have heard the term "thermal runaway"

in connection

with anything aeronautical is regarding ni-cad batteries.  An internal

melt down

starts to occur that is self feeding ... a little like the "china

syndrome" of a

nuclear reactor.

Accordingly, ni-cad batteries should have temperature sensing systems ...

which sure

blows the KISS principle.  Most ni-cad systems get converted back to

lead-acid or gel

cells, by maintenance departments that would just not rather have to do

all the

ni-cad hassle ... drain the charge, recharge (in steps) ... monitor

temperature, etc.

Dale Smith

Howard wrote:

Thermal runaway is an extremely poor term to apply to internal combustion
engines.    Heat transfer ability increases tremendously as temperature
differential increases.    Thus as waste heat dissipation increases with the
application of power the engine temperature rises beyond where you want it
to be, but it definitely does not run away because the transfer efficiency
goes up.
    It is in no way appropriate to use a term that suggests something akin
to neuclear meltdown for simple overheating......   If you exceed your
cooling capacity your engine will just run hotter.... perhaps too hot.
The idea of pressurized cooling systems it to allow the engine coolant temp
to rize to a level where cooling  is more efficient, and where the engine
operates more efficiently.....and of course to prevent coolant loss.
    If your temp exceeds the temp where pressure is greater than your
radiator cap pressure you will blow all your coolant out and have a melt
down......  that could be refered to as stupidity..... not thermal runaway.

                    H.W.

 
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