Ni-Cr Alloy Cheaper Than Steel On A Unit Power Basis

. . .
Ni-Cr alloy may cost 30 - 50 times more than
steel or Al on a weight basis but the power
output of, say, a large turbo fan is 70 times
higher than reciprocating engines on a unit
weight basis.
With $400/ton steel the Ni-Cr in a GT engine
is now actually cheaper than the steel in a
reciprocating engine. Maybe a Wankel would
be cheaper than GT but not by much.
Anyway most of the cost of all engines is
labor -- that's why you see so few multi engine
motor vehicles -- so it is penny wise pound
foolish to spend too much time on material cost
and not on design.
Turbo is DEFINITELY looking for heat
resistant materials but no engine is very
efficient at part load which is why series
hybrids or fuel cells will eventually take
over as gas reaches $20/gal.
Since Wankel is 1/4th the size and weight of
reciprocating it might do well in hybrids where
a lot of space and weight are devoted to
batteries.
What is the efficiency of a Wankel at optimum
rpm?
Besides the system could run on batteries to
a gas station in case of a coolant leak, which
I understand is a big disaster for Wankels.
As far as stationary power plants are
concerned GE has an industrial gas turbine
that is 60% efficient -- 50% higher than the best
steam power plants or diesel engines. It
weighs 100 tons and only runs at one rpm,
however.
Large aircraft engines -- 40% efficient, at
least at the one {wide open] speed they seem
to spend on 90% of the flight -- will remain
GT and even general aviation will eventually
go turbo because of its unparalleled reliability
and light weight.
Bret Cahill