Oddball engines and prototypes

[Grumph]

His last efforts were around a toroidal rotary engine. Again prototypes got built and ran. I'd need to see an animation to understand how it works but basically curved pistons chase each other around a circular bore track.
The bit that caught my eye was how they machined the curved pistons and the ring cylinder bores. The bores are in two case halves each with a circular track of half circle section. Bolted up, you've got a full circle, round bore.
Swarfie or Flettner could probably do the bores now on CNC but I do wonder about doing the curved pistons - I thought it was clever...

[WilDun]

His last efforts were around a toroidal rotary engine. Again prototypes got built and ran. I'd need to see an animation to understand how it works but basically curved pistons chase each other around a circular bore track.
The bit that caught my eye was how they machined the curved pistons and the ring cylinder bores. The bores are in two case halves each with a circular track of half circle section. Bolted up, you've got a full circle, round bore.
Swarfie or Flettner could probably do the bores now on CNC but I do wonder about doing the curved pistons - I thought it was clever...

Yes, I have thought and thought about that for years too and have come up with several "solutions" but a pretty daunting task as you say, especially the pistons! then the centrifugal forces acting on those pistons etc - so my last thoughts were, forget it!
Must say he was game in trying to change the established ideas on IC engines (as was Felix Wankel) - both set themselves a pretty daunting task in trying to convince manufacturers that it was worthwhile.

This conclusion of course is only from the point of view of a machinist!

[Grumph]

Yes, I have thought and thought about that for years too and have come up with several "solutions" but a pretty daunting task as you say, especially the pistons! then the centrifugal forces acting on those pistons etc - so my last thoughts were, forget it!
Must say he was game in trying to change the established ideas on IC engines (as was Felix Wankel) - both set themselves a pretty daunting task in trying to convince manufacturers that it was worthwhile.

This conclusion of course is only from the point of view of a machinist!

Yeah, the poor guy who had to make some of his stuff....One of the UK writers said of him that he would have gone a long way further if he'd been in partnership with an old fashioned Scots type engineer with the background to make anything...

What stopped the toroidal engine was the problem that the wankel was having at the same time - ignition. Lucas apparently gave him a prototype electronic ignition so spark rate wasn't a problem - but finding a plug that could stand the high rate of firing was. I think NSU and Mazda went to surface gap plugs around the time Bradshaw died.

[WilDun]

....One of the UK writers said of him that he would have gone a long way further if he'd been in partnership with an old fashioned Scots type engineer with the background to make anything...

Like Rolls & Royce, one a rich entrepreneur and the other a back street garage mechanic! and "bingo" ! (so I've heard anyway).

I believe that another thing which stopped the toroidal engine was the fact that the good old tried and true four and six cylinder inline engines were doing well (and still had really only begun development), also at a time when everyone was recovering from the war and money wasn't as plentiful for building anything revolutionary.

[guyhockley]

His last efforts were around a toroidal rotary engine. Again prototypes got built and ran. I'd need to see an animation to understand how it works but basically curved pistons chase each other around a circular bore track.
The bit that caught my eye was how they machined the curved pistons and the ring cylinder bores. The bores are in two case halves each with a circular track of half circle section. Bolted up, you've got a full circle, round bore.
Swarfie or Flettner could probably do the bores now on CNC but I do wonder about doing the curved pistons - I thought it was clever...

One of my jobs as an apprentice involved a rotating tool holder like that but it was to machine a dome into perspex blocks for a water sampling device.
The piston machining idea is great, though!

[guyhockley]

More on Bradshaw etc.
http://www.aqpl43.dsl.pipex.com/MUSE...toroidalIC.htm

[WilDun]

I like the cam mechanism as used by the Tschudi engine - not the complete engine, just the 'dwell' mechanism, it could be used in all sorts of applications in other machinery, even though it doesn't appear to have been successful in this engine.

[tjbw]

I should have read the book before I said anything!

Guess this thread is good for finding out about this sort of stuff in a leisurely fashion instead of the speculation and controversy of the big Ryger debate and the pressure to get it performing in a certain time!

So it looks like Bradshaw wasn't afraid to make a mistake or two! (and that is a good thing in my opinion ) but I'm still not convinced about the use of short conrods though, or even the need for one!
I wonder if there might be a couple of examples lying around somewhere in the UK or Europe, not recognised as being important which could be restored or copied just to find out.

Nice find by Grumph, and I've been finding out more about it in a leisurely fashion. Had to have a peep in the book to see the short conrod. I wonder if you could say this engine had two junk heads per cylinder.

Anyway, I think it's a very interesting design. The piston reminds me of a sketch in Draper's "Two Stroke Engine Design And Tuning" book published in 1960. Also the transfers from lower "supercharging chamber" feed the adjacent cylinder, and that's similar to the Ralph Olds patent for a stepped piston engine, that was featured earlier in this topic. It seems that the inlet port to that chamber has been "omitted for clarity".

[WilDun]

The sketch in Draper's book always interested me (depends on whether we are describing the same sketch of course!) and I'm sure that something along those lines could have been possible if there was some form of positive control of the outer portion of the piston especially when even light things like reeds are sometimes hard to control!
I'm not at home just now, but I'll dig up the book, scan the pic and post it later.

[Grumph]

Nice find by Grumph, and I've been finding out more about it in a leisurely fashion. Had to have a peep in the book to see the short conrod. I wonder if you could say this engine had two junk heads per cylinder.

Yeah, I didn't post that pic as my main point was the similarity of the basic layout to the Ryger.
Personally I think he was trying to do too much by intoducing the second layer of piston and compression - but by putting it on the drawing, I suppose he was covering the possibilities.

[ken seeber]

A "Commer knocker diesel 2 stroke outboard" from the UK ???

http://www.coxmarine.com/en/

It's a crappy website, but a friend said it's like the Commer, but he also said it has moving sleeves. Don't get too excited yet Fletto

So Guy, seeing you live up that way, please drop in and report back asap.

[guyhockley]

A "Commer knocker diesel 2 stroke outboard" from the UK ???

http://www.coxmarine.com/en/

It's a crappy website, but a friend said it's like the Commer, but he also said it has moving sleeves. Don't get too excited yet Fletto

So Guy, seeing you live up that way, please drop in and report back asap.

Website certainly doesn't tell you much, pictures look like staged nonsense - some bloke fixing the plumbing etc. Some of the claims are a bit dubious too, surely? "F1 concept of opposed pistons"? There have been proposals but has there ever been an actual OP F1 engine?
Maybe it sounded better than "The Nazi tech that bombed your grandparents"

Anyway that sparked a memory of John Lievesley being a fan of opposed piston engines and it turned out I had this on my hard drive. Wonder if he's the F1 engine designer in question?

[Frits Overmars]

A "Commer knocker diesel 2 stroke outboard" from the UK ??? http://www.coxmarine.com/en/
It's a crappy website...

Website certainly doesn't tell you much, pictures look like staged nonsense

My thoughts exactly, but I refrained from expressing them; I'm afraid I criticize enough as it is. Like below .

that sparked a memory of John Lievesley being a fan of opposed piston engines and it turned out I had this on my hard drive. Wonder if he's the F1 engine designer in question?

I nice read (I mean that) and quite instructive. I always thought that the difference between metric degrees and imperial degrees was temperature-only, with Kelvin, Celsius, Fahrenheit, etc. But the picture below suggests there's a goniometrical difference as well: that '20 degree included angle' looks exactly 10° to me.

And there were some other surprises that I would not expect from a F1-designer, especially one who is fond of two-strokes. Like his remark, talking about an engine design with a fixed 40 mm stroke:

If we make the cylinder bore smaller to reduce the risk of overheating the exhaust piston crown, then we reduce the available port area.

So what? Halving the bore will halve the port area, but it will quarter the cylinder capacity, so it will double the specific port area. Everything you could wish for...

The next eye opener:

Junkers produced a successful diesel aero engine... it used a single crank to control the piston set that was adjacent to the crank via conventional connecting rods,
while the pistons of the opposite set were attached to the crank by pairs of very long connecting rods outside and parallel to the cylinders.

I always thought I knew my Junkers, especially their most successful diesel aero engine, the Jumo 205, pictured below with two crankshafts....

[guyhockley]

My thoughts exactly, but I refrained from expressing them; I'm afraid I criticize enough as it is.

Oh, I don't know, you let me get away with my wildly innacurate "Nazi tech" remark!

[tjbw]

Website certainly doesn't tell you much, pictures look like staged nonsense - some bloke fixing the plumbing etc. Some of the claims are a bit dubious too, surely? "F1 concept of opposed pistons"? There have been proposals but has there ever been an actual OP F1 engine?

....

Anyway that sparked a memory of John Lievesley being a fan of opposed piston engines and it turned out I had this on my hard drive. Wonder if he's the F1 engine designer in question?

I'm a big fan of opposed piston engines, from the Jumo to Achates, but none have been used in F1 as far as I'm aware.

F1 engines are homologated, with V6 90 degree poppet valve four stroke engines at the moment.

I did find this possible F1 connection, copied from https://www.theengineer.co.uk/issues...tors-together/

" ... David Cox, who emerged as the brains behind the Brabham BT46B ‘fan car’ which stunned the F1 world by winning on its debut at the 1978 Swedish Grand Prix. Cox has wide experience outside the world of motorsport with projects such as the Thames Barrier where he was in charge of the mechanical design section and Eurofighter."

Also, Ken - hope you are well!