Stephen Harding wrote in message ...
alfred montestruc wrote:

"Keith Willshaw" wrote in message ...

"alfred montestruc" wrote in message

Point of fact, I am very sure that alloys needed either existed, or
reasonable substitutes did.

Evidence please

Artillery gun tubes of that era. They were (obviously) subjected to
high stresses for many thousands of repititions. Obviously the
pressures in a gun tube near the breech during fireing of an artillery
gun are much larger than in an IC engine that has a peak compression
ratio of 10:1 at most.

Imagine if you will I take say a 75mm cannon, hone the bore free of
rifling, then cut it into 6" section to make cylinders for a radial
engine. I can make the engine block out of a ductile iron casting,
the pistons, rods, and shaft from forgings of the same alloy as the
gun tube is made from.

I can then machine fins on the outside of the cylinders and bolt them
to the block. See any showstoppers?

Weight? We do want to fly, rather than tow, this thing around.

Duh!

What is the thickness of a cannon barrel wall compared to an
engine cylinder?


Suggest you look up an engineering text on mechanics of materials and
thermodynamics and work out first the pressure on the inside of the
cylender via thermo calcs, then the required thickness via mechanics
of materials, and the strength of the material used.

I'll give you a hint, cast iron (common material used in IC engines in
WWI) will have a useful strength a whole lot lower than most any grade
of steel. Note also that for serious engine applications you need to
keep stresses lower than the endurance limit of the material, else
have fatigue cracks and failures in service.

http://www.anvilfire.com/FAQs/cast_iron.htm


Typical modern gun steels will have tensile stengths of ~150,000 psi,
with yields stress like 130,000 psi and endurance limits in the range
of 50,000psi. While I am sure the steels used at the start of WWI
were not that good, they may well have had endurance limits in the
30,000psi to 40,000 psi range. When you compaire that to the 20,000
odd of the very best cast iron grades one could get, I think you
should see the point.



What happens to the strength of that cylinder when we reduce
its thickness with machined cooling fins?

What would the weight of an engine built in this manner be,
compared to the engines of the day?

They've been making cannons for 600 years. Not certain I'd
want one as a cylinder in my truck, let alone a combat
aircraft.


SMH