DIYbanter - View Single Post - More on IC Self-Reproducing Machine Tools

In article .com,
wrote:

B.B. wrote:
Go research model aircraft 2-stroke diesel engines. Some are
literally a piston, a crank, and a cylinder with a carb. No plugs,
injectors, valves, linkage, timing, or anything else. Just have to spin
the crap out of it to get started. You could couple that to an air
motor for starting, then the air motor could act as a vane-style
compressor once the engine started. But I think that style of engine is
limited in displacement.

Yes, the vane style is good for high speed, good power density, and a
high pressure input, but performs miserable as a compressor. An IC vane
style motor has been constructed, I believe. I forget what it is
called. Ericsson Cycle? I don't think that is right.

The 2-stroke diesels might be a good choice. The Army is going all
diesel, I believe. Do 2-stroke diesels scavenge with air/fuel or do
they use an injector? I know the little ones do, but how about larger
ones? .49 cu in is enough for my Unimat One, or a small machine, not
much more. Scale is still an issue here.

The little ones I was alluding to depend a great deal on momentum.
The momentum of the flywheel to force 'em through a complete cycle, and
the momentum of the column of air entering/exhaust leaving to scavenge.
Carburated, so air/fuel mix. Like I said, these are small
displacement--as in fractions of a CC. If you go into larger sizes
you'll likely need to go with injection.
Many of the Military's HET trucks run from Detroit Diesel two
strokes. These are often V8 engines with a blower mounted on top,
between the banks of cylinders. Air is inducted through ports, with the
exhaust valved at the top. Fuel is injected with unit injectors, which
seem to be a lot less touchy than centralized high pressure systems.
For a critter like that to replicate, it needs to be able to cast a
rather complex engine block, machine a blower with a helix shape and
tight tolerances, plus make ball bearings, gears, rubber seals, and
ported cast iron liners. May not be doable.
Could be more practical to use sterling engines and settle for the
low horsepower.

It's nice to see some traffic on this thread! Were you all napping
after that big Thanksgiving dinner?

I've been rebuilding my apartment after a failed move.

--
B.B. --I am not a goat! thegoat4 at airmail dot net