There are three types of engines. But what if we’re missing something important.

1. Steam engine (including gas turbine and Stirling cycle). Nuclear falls into this category, as does coal and oil. Driven by gas expansion produced by heat.

2. Internal combustion engine. Includes jet engine.

3. Electical motor. Includes ion drive.

And that’s just about all. Apart from niche engines like clockwork, and watermill. And slave power.

There is so much difference between an electrical motor and a piston or heat engine. Could there be another type of engine that is as different from these as they are from each other?

mollwollfumble said:

There are three types of engines. But what if we’re missing something important.

1. Steam engine (including gas turbine and Stirling cycle). Nuclear falls into this category, as does coal and oil. Driven by gas expansion produced by heat.

2. Internal combustion engine. Includes jet engine.

3. Electical motor. Includes ion drive.

And that’s just about all. Apart from niche engines like clockwork, and watermill. And slave power.

There is so much difference between an electrical motor and a piston or heat engine. Could there be another type of engine that is as different from these as they are from each other?

Graphics engine for games

mollwollfumble said:

There are three types of engines. But what if we’re missing something important.

1. Steam engine (including gas turbine and Stirling cycle). Nuclear falls into this category, as does coal and oil. Driven by gas expansion produced by heat.

2. Internal combustion engine. Includes jet engine.

3. Electical motor. Includes ion drive.

And that’s just about all. Apart from niche engines like clockwork, and watermill. And slave power.

There is so much difference between an electrical motor and a piston or heat engine. Could there be another type of engine that is as different from these as they are from each other?

Rocket engines though they are a sort of internal combustion, how about Nano engines, not sure what powers them.

sorry to quibble, but I understand jet engines to be a type of gas turbine engine. Perhaps you meant steam turbine in category one?

I would classify as external combustion engines, internal combustion engines, and electric engines.

Then try and lump nuclear in with external combustion engines and try to think of a word that replaces “combustion” to include and external heat source. Essentially the first two all work on the same principle of solids or liquids turning into gases and expanding according to Boyles Law, this expansion pressure being convetered into mechanical energy.

mollwollfumble said:

There are three types of engines. But what if we’re missing something important.

1. Steam engine (including gas turbine and Stirling cycle). Nuclear falls into this category, as does coal and oil. Driven by gas expansion produced by heat.

2. Internal combustion engine. Includes jet engine.

3. Electical motor. Includes ion drive.

And that’s just about all. Apart from niche engines like clockwork, and watermill. And slave power.

There is so much difference between an electrical motor and a piston or heat engine. Could there be another type of engine that is as different from these as they are from each other?

Not sure why clockwork and watermill are considered “niche”, and slave power is just a subset of muscle engines, which is certainly another type.

I’d dispute putting IC and jet in the one category as well.

As for other other types, how about momentum transfer engines (such as tidal)?

Warp engine assuming its actual possible

Cymek said:

Warp engine assuming its actual possible

Possibly a sophisticated momentum transfer engine?

Not sure.

party_pants said:

sorry to quibble, but I understand jet engines to be a type of gas turbine engine. Perhaps you meant steam turbine in category one?

I would classify as external combustion engines, internal combustion engines, and electric engines.

Then try and lump nuclear in with external combustion engines and try to think of a word that replaces “combustion” to include and external heat source. Essentially the first two all work on the same principle of solids or liquids turning into gases and expanding according to Boyles Law, this expansion pressure being convetered into mechanical energy.

Yes. Exactly what I was trying to say. I couldn’t say “external combustion” because the external heat source doesn’t have to be by combustion. And if the gas comes from a compressed gas storage instead of heat, then perhaps it’s right to call it an “external gas engine”.

So the first two are so similar that they could be lumped together.

Even a Crookes radiometer, which is a a type of engine, classifies as a heat engine.

What about other proposed space travel engines, the Bussard ramjet for example

OK, if we want 3 types + 1 extra I’m going for:
1. Heat engine
2. Mechanical potential energy engine
3. Chemical potential energy engine
+1. Momentum transfer engine

Where do you put a trebuchet?

The Rev Dodgson said:

mollwollfumble said:

There are three types of engines. But what if we’re missing something important.

1. Steam engine (including gas turbine and Stirling cycle). Nuclear falls into this category, as does coal and oil. Driven by gas expansion produced by heat.

2. Internal combustion engine. Includes jet engine.

3. Electical motor. Includes ion drive.

And that’s just about all. Apart from niche engines like clockwork, and watermill. And slave power.

There is so much difference between an electrical motor and a piston or heat engine. Could there be another type of engine that is as different from these as they are from each other?

Not sure why clockwork and watermill are considered “niche”, and slave power is just a subset of muscle engines, which is certainly another type.

I’d dispute putting IC and jet in the one category as well.

As for other other types, how about momentum transfer engines (such as tidal)?

Don’t like IC and jet in one category? They are both internal combustion engines. They are even powered by almost the same range of fuels and the same chemical reactions. Engines based on gears, such as the Wankel, and centrifugal pumps running backwards, fit neatly between the two.

Tidal and wave power are only used as generators, not as engines. I wouldn’t want to use them to grind grain for instance.

The main momentum transfer engine is flywheel power.

I’m not sure if Project Orion, dropping suitcase nukes the back of a spacecraft, would fit into one of those categories, but it’s something of a niche engine.

Peak Warming Man said:

Where do you put a trebuchet?

Outside the walls of the enemy castle usually

Cymek said:

What about other proposed space travel engines, the Bussard ramjet for example

That’s an internal combustion engine.

Ramjet = flammable onboard and oxygen from surrounding gas
Rocket = flammable and oxygen onboard
Bussard = oxygen onboard and flammable from surrounding gas

No real difference (apart from technical impossibility)

Peak Warming Man said:

Where do you put a trebuchet?

I guess they are a type of muscle power storage devices. Same as bows.

The Rev Dodgson said:

OK, if we want 3 types + 1 extra I’m going for:
1. Heat engine
2. Mechanical potential energy engine
3. Chemical potential energy engine
+1. Momentum transfer engine

I’ll pay that one.

Peak Warming Man said:

Where do you put a trebuchet?

Interesting.

I had that in with clockwork. There are two types of energy storage used in clockwork, a falling weight and elastic energy in a spring. There are two ways of storing energy for a trebuchet, a falling weight and elastic energy in a type of spring.

Sentient coloured tank engines ?

How about a search engine.

Cymek said:

Sentient coloured tank engines ?

what colour is sentient?
what colour is a sentient tank in the dark?

bucolic3401 said:

How about a search engine.

I wondered about computer/software engines, they are a completely different definition of engine

Cymek said:

Sentient coloured tank engines ?

As in Hooloovoo? I’d put that in with slave power. Along with engines powered by horses, and hamsters. I count bicycle power as slave power, too, although some may disagree.

party_pants said:

Cymek said:

Sentient, coloured tank engines ?

what colour is sentient?
what colour is a sentient tank in the dark?

It should have some commas

Sentient, coloured, tank engine ?

mollwollfumble said:

The invention of the modern safety bicycle post-dates the abolition of slavery in most places.

Why not just call it human muscle power?

mollwollfumble said:

I count bicycle power as slave power, too, although some may disagree.

The invention of the modern safety bicycle post-dates the abolition of slavery in most places.

Why not just call it human muscle power?

Would you count a molecular motor as an engine?

party_pants said:

mollwollfumble said:

I count bicycle power as slave power, too, although some may disagree.

The invention of the modern safety bicycle post-dates the abolition of slavery in most places.

Why not just call it human muscle power?

Well, it could be any animal, on a microscopic scale it could even be a bacteria.

That takes me on to a thought about linear vs rotary. Microscopic chemical energy produces linear motion (myosin and actin acting together to make muscles contract) and also rotary motion (spinning helix of a flagella).

An electric engine can be rotary, or it can be a linear induction motor.

A clock’s motion is rotary, but a trebuchet’s motion is near-linear.

A car engine produces linear motion (piston) converted to rotary motion, then converted back to linear motion as car rolls along the road. I see no reason why an internal combustion engine couldn’t go straight from linear motion (pistons) to linear motion (car along road) using a ratchet mechanism.

… and the other way around …

A rocket engine produces linear motion, but I see no reason why it couldn’t be adapted to directly produce rotary motion (rather than external conversion from linear to rotary).

I’m still not getting near a useful alternative to internal combustion + steam/gas + electric. Unless I look more closely into Rev D’s momentum transfer and how it works without gears.

I tried a while back to design a nuclear heat engine that worked using the direct propulsion from either fission products or the momentum of thermal radiation. Neither worked particularly well.

esselte said:

Would you count a molecular motor as an engine?

Yes.

windmill, obv

Osmotic engine? Engine powered by osmosis, would that be a different type?

mollwollfumble said:

Osmotic engine? Engine powered by osmosis, would that be a different type?

Hold on. A nerve cell would count as an osmosis-powered engine.

If dropping a suitcase nuke out the back of a spacecraft counts as a different type of engine, then what about an afterburner?

I’d included windmill in with gas turbine, but perhaps I shouldn’t have, because I’ve missed an extremely important type of engine. A hydraulic motor.

“A hydraulic motor is a mechanical actuator that converts hydraulic pressure and flow into torque and angular displacement (rotation). The hydraulic motor is the rotary counterpart of the hydraulic cylinder as a linear actuator.” ‘Hydraulic motor types: gear and vane motors, Gerotor motors, Axial plunger motors and Radial piston motors, where the piston can push either inwards or outwards.”

https://www.crossco.com/blog/choosing-hydraulic-motor-medium-speed-1000-rpm-application

I’d dismissed pneumatic engines too lightly, too.