The discussion of ICEs in future made me wonder.

ROTAX for example makes gasolene piston engines for:

• Aircraft
• ATVs
• Snowmobiles
• Motorcycles
• Marine

What’s the difference, if any, between gasolene piston engines for different uses?

mollwollfumble said:

The discussion of ICEs in future made me wonder.

ROTAX for example makes gasolene piston engines for:

• Aircraft
• ATVs
• Snowmobiles
• Motorcycles
• Marine

What’s the difference, if any, between gasolene piston engines for different uses?

perhaps not the sort of thing you’re meaning, and i’m no expert…

many engines work at different altitudes, aircraft especially, so air/fuel mixture has to be compensated for rarefied air (+ lower atmospheric pressure, + cold). Special attention to safe limits too for reliability.

to save on complexity and weight, an aero engine can be air-cooled, it’s mostly working away from the ground so you don’t have the higher ambient temperatures from ground surface heating, and there’s plenty of air moving, or the planes moving. The prop moves air too.

possibly some duplication of ignition system for aero, and special consideration to the fuel system, because a loss of power tends to result in whatever falling out of the sky.

aero engines maybe need operate different angles, including upside down, so a typical wet sump isn’t going to work I wouldn’t expect. Carburetors with a float and bowl wouldn’t do, but there’s AD Carburetors, and injection systems I guess instead.

RPM in aero’s probably kept within a lower range, or tighter range, there are things like maximum prop speed to consider.

moving on to marine…

pumping sea water through for cooling is really good at just that, cooling, so of two-strokes you can probably run less oil in the fuel mix, or inject less oil. The corrosiveness of sea water is a big consideration.

moving on to snowmobiles….

these’d have to be able to endure extremely cold temperatures, and start in cold temperatures.

and tere you ave it, a few naive thoughts on the subject

For aero engines there’s a little bit of a trend to mini turboprop engines. Some of them out on the market now as small as the 100-150 hp range. Lightweight, more reliable than piston engines.

… or do they count as ICE for the purposes of this thread?

mollwollfumble said:

The discussion of ICEs in future made me wonder.

ROTAX for example makes gasolene piston engines for:

• Aircraft
• ATVs
• Snowmobiles
• Motorcycles
• Marine

What’s the difference, if any, between gasolene piston engines for different uses?

Transition did a pretty good review, but here’s a little more.
Every type of engine has the desire to be as light as possible, though it is more important for aircraft, of course. Two-stroke engines were quite popular up until recent times as they are lighter, simpler, and make more power-per-litre as they have twice as many power strokes for the same time. They are, however, fairly dirty on the emissions side of things as a small amount of oil (about 1:50) has to be added to the fuel to lubricate the engine and that oil creates a lot more emissions compared to a regular four-stroke.
(There is a way to eliminate the need to add oil to a two-stroke, but hardly anyone does it and it adds a fair bit to the price and weight)

Piston aircraft engines area bit of an odd one, as they have to be very light, very reliable, and should be very light. The current Lycomings & Continentals, etc, haven’t really changed much in many decades and the reason for that is for what they’re used for, they don’t really have to. Aviation is usually very slow on introducing new technology that has any chance of reducing reliability. Anyway they typically use a large-capacity engine (235 cubic inches or about 3.8 litres is a small one) for a couple of reasons.
- They have to be very reliable and so because the engines need to have a low stress on them, they are made with a large capacity, so the power-per-litre is relatively low.
- When the propeller is bolted directly to the front of the crankshaft the maximum RPM is usually about 2,700 as with more revs than that the tips of the prop will go supersonic and that makes for a lot of noise (listen to a Cessna 210 or 206 on takeoff, they run 2850 rpm and the props make a hell of a racket) and also reduces the prop efficiency.

Transition also mentioned small turboprop engines and they are indeed becoming cheaper (thought they are still quite expensive) and are very light (you can pick one up without too much trouble) and so should be a good thing. They don’t suffer from as much shock-cooling – reducing power too quickly, which on an aircraft piston engine can cause cracks in the bottom of the bolt-on cylinders, which, worst case, can literally blow off and that really ruins your day – so should be a lot more reliable and have lower running costs. A typical light aircraft piston engine needs a full rebuild between 1,500 to 2,000 hours. A good turbine will easily go double that, though the rebuild cost can be significantly higher if you haven’t looked after the engine properly; they still need careful power changes, to let the internal temperatures change smoothly.
Turbines can often run on regular fuel or diesel or kerosene, etc, but often with some small restrictions such as maximum altitude and/or max power, etc.

Thanks all, especially about the need to fly upside down, I hadn’t thought of that.

> Piston aircraft engines area bit of an odd one, as they have to be very light, very reliable, and should be very light. The current Lycomings & Continentals, etc, haven’t really changed much in many decades and the reason for that is for what they’re used for, they don’t really have to. Aviation is usually very slow on introducing new technology that has any chance of reducing reliability. Anyway they typically use a large-capacity engine (235 cubic inches or about 3.8 litres is a small one) for a couple of reasons.

The Rotax engines seem to be favoured by home built and light aircraft. They have a flat four 1.35 litre 4-stroke engine and a propeller speed reduction gear of 2.43:1. Sort of very similar size and configuration to a Kawasaki 1400GTR motorbike.

mollwollfumble said:

Thanks all, especially about the need to fly upside down, I hadn’t thought of that.

> Piston aircraft engines area bit of an odd one, as they have to be very light, very reliable, and should be very light. The current Lycomings & Continentals, etc, haven’t really changed much in many decades and the reason for that is for what they’re used for, they don’t really have to. Aviation is usually very slow on introducing new technology that has any chance of reducing reliability. Anyway they typically use a large-capacity engine (235 cubic inches or about 3.8 litres is a small one) for a couple of reasons.

The Rotax engines seem to be favoured by home built and light aircraft. They have a flat four 1.35 litre 4-stroke engine and a propeller speed reduction gear of 2.43:1. Sort of very similar size and configuration to a Kawasaki 1400GTR motorbike.

Except for the completely different cylinder layout and specific power and lack of multi-speed gearbox.

Pffft petrol powered engines water is the way to go

Zarkov said:

Pffft petrol powered engines water is the way to go

That’d be fabulous, but I’ve not been able to get one.

Michael V said:

Zarkov said:

Pffft petrol powered engines water is the way to go

That’d be fabulous, but I’ve not been able to get one.

Send me money Zarkov@omegefour.com.au and I’ll send you the plans

Zarkov said:

Michael V said:

Zarkov said:

Pffft petrol powered engines water is the way to go

That’d be fabulous, but I’ve not been able to get one.

Send me money Zarkov@omegefour.com.au and I’ll send you the plans

How much money? How difficult to build to the plans?

Zarkov said:

Michael V said:

Zarkov said:

Pffft petrol powered engines water is the way to go

That’d be fabulous, but I’ve not been able to get one.

Send me money Zarkov@omegefour.com.au and I’ll send you the plans

WWII Germans had a bit of trouble with water of the heavy variety.

Michael V said:

Zarkov said:

Michael V said:

That’d be fabulous, but I’ve not been able to get one.

Send me money Zarkov@omegefour.com.au and I’ll send you the plans

How much money? How difficult to build to the plans?

I’m not in it to make money but do need some to build my metal poisoning removal machine whatever you think its worth
I made it from stuff around my house and a few old computers/dvd players etc

Zarkov said:

Michael V said:

Zarkov said:

Send me money Zarkov@omegefour.com.au and I’ll send you the plans

How much money? How difficult to build to the plans?

I’m not in it to make money but do need some to build my metal poisoning removal machine whatever you think its worth
I made it from stuff around my house and a few old computers/dvd players etc

Cool.

>Thanks all, especially about the need to fly upside down, I hadn’t thought of that.

need be able to drop rapidly too

transition said:

>Thanks all, especially about the need to fly upside down, I hadn’t thought of that.

need be able to drop rapidly too

Would a radial engine work ?

7 STRANGEST New Engines
https://www.youtube.com/watch?v=bBrUrgNf5y8

Tau.Neutrino said:

transition said:

>Thanks all, especially about the need to fly upside down, I hadn’t thought of that.

need be able to drop rapidly too

Would a radial engine work ?

wouldn’t want too much oil washing around, like a sump. Bottom chambers in the old radial aero engines still seemed to get oiled up I reckon. They’d likely be the pots(plugs) that got oiled up, especially in worn engines

here’s a continental aero engine, as used in stuart tanks, dad had one, a tank.

Tau.Neutrino said:

7 STRANGEST New Engines
https://www.youtube.com/watch?v=bBrUrgNf5y8

Yep. Saw that.

Interesting discussion of small turboprop vs piston engine for aviation.

“Piston engines are more efficient than turboprops, so their operational cost are lower. This also means that the system mass (engine plus fuel) for a trip is lower once you go beyond small ranges. In a helicopter, the engine mass is more important, because average flight times are much shorter, so you find many helicopters with turbo engines and only few with pistons.”