Quote from: PR19_Kit on May 30, 2023, 11:11:06 AM

Quote from: jcf on May 30, 2023, 10:35:31 AMA rotary of sorts as the 3-cylinder radial engines, plural, are mounted directly to the non-steering front wheels:

It steers from the rear wheel?   

Be afraid, be VERY afraid! 

C'mon it worked fine on Bucky Fuller's Dymaxion ... oh, er ... 

Cheers folks.

The reason I asked about this is that I'm currently reading Kingdom Of The Wicked by lawyer-not-engineer Helen Dale. It's set in 33AD in Jerusalem, but in this timeline, the Romans had an industrial revolution about 200 years previously, so they're holding down the provinces with CCTV and MRAPs.  She's got cars and armoured vehicles    driving around with exposed rotary piston engines mounted aircraft-style at the front, as confirmed by a couple of the drawings that illustrate the books.

I had a polite but brief conversation with her on Twitter about it, but she shut it down as soon as she realised I was skeptical: I imagine I'm not the first person to take her to task over it   I wanted to make sure that I wasn't missing something when I said that rotary-piston-engined cars are almost unheard of for a long list of good reasons. From some of what she said, I'm fairly certain that she got confused between rotary piston engines and Wankel rotaries. There's a couple of other questionable tech/military things in there too.

I should emphasise, in her defence, that the books are NOT about technology and the gaffs don't spoil them. The real point of the alt-history exercise is to see what would happen if the 'Jesus situation' was dealt with by a 'modern' society with 'modern' concepts of law and justice, and the history of law really IS her ballpark. It wouldn't make any difference to the story if the vehicles were powered by inline engines, coal or anti-matter (and I'm still laughing at the Roman blue movie called "Deborah Does Damascus"...   )

One of the MRAPs illustrated is just an Sd.Kfz.251 halftrack with a rotary engine grafted onto the front. It'd be easy enough to make a model of, just not so easy to defend against the inevitable "but why?" questions...

Quote from: Weaver on May 31, 2023, 04:55:20 AMOne of the MRAPs illustrated is just an Sd.Kfz.251 halftrack with a rotary engine grafted onto the front. It'd be easy enough to make a model of, just not so easy to defend against the inevitable "but why?" questions...

...but what is a rotary engine in this position supposed to drive? There have been designs with rotary engines inside of wheels (what makes sense, to a point, because the engine block rotates), e.g. for motorbikes, but "a rotary engine grafted onto the front" makes NO sense at all, unless it's a fixed RADIAL that drives something inside of the vehicle? 

As a scary example, the German Megola motorbike with a five cylinder engine in the front(!) wheel.

I think it would be more like this:

radial truck

 A front mounted rotary could drive a shaft leading back to one of the axles via a rather complex spur gear drive set, but it would make very little engineering sense to do that.

The first version of the Radley-England Waterplane was powered by three Gnome rotaries mounted in a row driving an offset propeller shaft via chains. I suppose a similar setup could be used to power a ground vehicle, of course you'd need some sort of clutch and transmission system.

Of course it's all moot in terms of the author's scenario as a Roman "Industrial Revolution" wasn't going to happen as the necessary preliminary elements weren't in place in terms of materials and fabrication technologies, ditto the understanding of physical laws and mathematics. Most importantly in a society with an energy economy based on human labour, much of it slave, there was little to no consideration of labour-saving or efficiency. It simply didn't matter.

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There have been numerous attempts at rotary piston engines, IC and steam:

Rotary Piston IC

Rotary Piston Steam
Twelve pages of various attempts.

Quote from: Dizzyfugu on May 31, 2023, 05:28:52 AM...but what is a rotary engine in this position supposed to drive? There have been designs with rotary engines inside of wheels (what makes sense, to a point, because the engine block rotates), e.g. for motorbikes, but "a rotary engine grafted onto the front" makes NO sense at all, unless it's a fixed RADIAL that drives something inside of the vehicle? 

Well quite. I can imagine ways to do it (the example Jon provided is one), but they don't make much engineering sense. Probably the closest to what's drawn would be to have a ring gear attached to the back of the crankcase around the crankshaft and have that driving a gear train that took the power down to a conventional gearbox and transmission at about wheel hub height.

Quote from: Lord_Voyager on May 31, 2023, 05:34:21 AMI think it would be more like this:

radial truck

Yes that's the other way: put the engine in the 'middle' of the chassis with the crankshaft supported at the back and a power take-off at the front or vice versa. Still leave an awkward and vulnerable slot in the bodywork though.

Quote from: jcf on May 31, 2023, 10:00:35 AMOf course it's all moot in terms of the author's scenario as a Roman "Industrial Revolution" wasn't going to happen as the necessary preliminary elements weren't in place in terms of materials and fabrication technologies, ditto the understanding of physical laws and mathematics. Most importantly in a society with an energy economy based on human labour, much of it slave, there was little to no consideration of labour-saving or efficiency. It simply didn't matter.

When the book came out it provoked quite a back-and-forth between academics and historians, and several made similar points. Her point of departure from real history is that Archimedes survives the seige of Syracuse in 212BC, is "Operation Paperclipped" by the Romans, and goes on to develop calculus and a range of useful technologies, which then snowballs, before the widespread influx of slaves from the Roman conquests of Greece, Carthage and Gaul. This leads to a successful push for the abolition of slavery led by the Stoics, and in the struggle between Emperors and the Senate, the latter wins out (as in the English Civil War) rather than the former (as in real life).

Here's the essay from the back of book 1 in which Dale explains her creative process and how she ended up where she did:

https://www.libertarianism.org/publications/essays/authors-note-kingdom-wicked


And here's a couple of essays about Roman industrialization:

This one references KotW: https://medium.com/@MarkKoyama/could-rome-have-had-an-industrial-revolution-4126717370a2

This one doesn't: https://acoup.blog/2022/08/26/collections-why-no-roman-industrial-revolution/

Rotary engines aren't very suitable for cars. They can't be throttled well: rotary aircraft engines from the period were mostly used at either full throttle or idle, with any setting in between requiring careful adjustment. This is acceptable in an aircraft, but in a car you're constantly adjusting the throttle setting.
The huge inertia of the rotating block would also make changing gear a slow process.

Quote from: Hobbes on May 31, 2023, 11:49:07 PMThe huge inertia of the rotating block would also make changing gear a slow process.

Not to mention some 'interesting' handling issues.................. 

Quote from: jcf on May 31, 2023, 10:10:50 AMThere have been numerous attempts at rotary piston engines, IC and steam:

Rotary Piston IC

I love the name "Jasper Explosive Motor".

How are rotating cylinder type rotary engines lubricated?  I would assume by using a total loss system.  ISTR a lot of talk of castor oil in the WW1 Biggles books.

Were multi row rotaries ever tried?

Quote from: zenrat on June 01, 2023, 03:50:55 AM

Quote from: jcf on May 31, 2023, 10:10:50 AMThere have been numerous attempts at rotary piston engines, IC and steam:

Rotary Piston IC

I love the name "Jasper Explosive Motor".

How are rotating cylinder type rotary engines lubricated?  I would assume by using a total loss system.  ISTR a lot of talk of castor oil in the WW1 Biggles books.

Were multi row rotaries ever tried?

A lot of WWI pilots suffered from diarrhea due to the amount of castor oil they accidentally imbibed. Not exactly the glamorous image eh?

The lubrication was total loss, and also on 'Monosoupape' engines, the only means of throttling them for landing was a 'blip' switch with temporarily cut the ignition, but did nothing to cut the fuel flow. The resultant build up of oil and petrol in the cowling could be quite dangerous, which is why you see those top-half-only cowlings on a lot of WWI fighters.

So I bothered to read the wikipaedia page.

The lubrication system, as with all rotary engines, was a total-loss type in which castor oil was pumped into the fuel–air mix. Castor oil was used because it did not readily dissolve into the fuel, and because it offered lubrication qualities superior to other available oils. Over two gallons of castor oil were sprayed into the air during each hour of engine operation. This explains why most rotaries were fitted with cowls, with the lowermost quarter omitted to direct the spray of castor oil away from the pilot.[6] Unburnt castor oil from the engine had a laxative effect on the pilot if ingested.

https://en.wikipedia.org/wiki/Gnome_Monosoupape