Building a small scale IC engine

[Phoebe]

I was thinking the other day about how it would be fun to have a tiny,
working internal combustion engine (ie something that would fit in your
palm) which didn't necessarily need to have great power or efficiency,
though it would be nice. So I did a little web research, and found that
people actually do make these as a hobby, generally by making scale models
of existing engines. Many of these people are amateurs with no engineering
background, which may be part of why they copy existing engines and shrink
them down, rather than producing their own designs. Of course the first
thing that pops into my mind is, how scalable are the forces/physics
involved? Halve all of the dimensions, and the force/pressure on the various
parts wouldn't scale down linearly, would they? On that thought, would an
engine be more reliable if all dimensions were scaled up, or scaled down,
assuming that all materials remained the same? (Not to mention the question
of tolerances and clearances) Then there's the whole thing about heat
transfer and buildup, and any number of problems. Of course these engines
would probably be run with no load except for the flywheel, and for short
periods

If you wanted to make a tiny, palm sized engine, do you think that you would
prefer to scale down an existing design, or create your own original one?

Also, what kind of fuel would you run it on?

[n***@hotmail.com]

I don't know how you would make one or how effecient this would be, but
running it on gasoline would be so cool, not only is t so readily
available but it also emphasises the fact the that you have a miniature
car engine in the palm of your hand!

[Guru]

Post by Phoebe
I was thinking the other day about how it would be fun to have a tiny,
working internal combustion engine (ie something that would fit in your
palm) which didn't necessarily need to have great power or efficiency,
though it would be nice. So I did a little web research, and found that
people actually do make these as a hobby, generally by making scale models
of existing engines. Many of these people are amateurs with no engineering
background, which may be part of why they copy existing engines and shrink
them down, rather than producing their own designs. Of course the first
thing that pops into my mind is, how scalable are the forces/physics
involved? Halve all of the dimensions, and the force/pressure on the
various parts wouldn't scale down linearly, would they? On that thought,
would an engine be more reliable if all dimensions were scaled up, or
scaled down, assuming that all materials remained the same? (Not to mention
the question of tolerances and clearances) Then there's the whole thing
about heat transfer and buildup, and any number of problems. Of course
these engines would probably be run with no load except for the flywheel,
and for short periods.

Are we talking about the same things? There are many such small air-cooled
internal combustion engines for sale in hobby shops, for powering model
aircrafts and model power boats? Why do you want to re-invent the wheel?

Post by Phoebe
If you wanted to make a tiny, palm sized engine, do you think that you
would prefer to scale down an existing design, or create your own original
one?
Also, what kind of fuel would you run it on?

[Peter Lowrie]

Go to the library and get a magazine on model engineering

Post by Guru

Post by Phoebe
I was thinking the other day about how it would be fun to have a tiny,
working internal combustion engine (ie something that would fit in your
palm) which didn't necessarily need to have great power or efficiency,
though it would be nice. So I did a little web research, and found that
people actually do make these as a hobby, generally by making scale models
of existing engines. Many of these people are amateurs with no engineering
background, which may be part of why they copy existing engines and shrink
them down, rather than producing their own designs. Of course the first
thing that pops into my mind is, how scalable are the forces/physics
involved? Halve all of the dimensions, and the force/pressure on the
various parts wouldn't scale down linearly, would they? On that thought,
would an engine be more reliable if all dimensions were scaled up, or
scaled down, assuming that all materials remained the same? (Not to mention
the question of tolerances and clearances) Then there's the whole thing
about heat transfer and buildup, and any number of problems. Of course
these engines would probably be run with no load except for the flywheel,
and for short periods.

Are we talking about the same things? There are many such small air-cooled
internal combustion engines for sale in hobby shops, for powering model
aircrafts and model power boats? Why do you want to re-invent the wheel?

Post by Phoebe
If you wanted to make a tiny, palm sized engine, do you think that you
would prefer to scale down an existing design, or create your own original
one?
Also, what kind of fuel would you run it on?