Oddball engines and prototypes

[husaberg]

nice little demo

[WilDun]

nice little demo

A modified version of that principle has been used in shaping machines for over 100 years, it is a sound design which incorporated a quick return stroke (as seen in Husa's animation above) - the overall length of stroke was also adjustable, by moving the position of the beam pivot up or down. Some I'm told were adjustable by moving the crankpin. - Cool machines, those shapers!

https://www.youtube.com/watch?v=Omsyy-RiaqU

[WilDun]

I did some comparative calculating with an engine where the con rod length is a conservative twice the stroke size, and an engine with an infinite con rod length, aka a Scotch Yoke geometry.
So the claim of 25% less peak acceleration in the Scotch Yoke is correct, but irrelevant.
Summary: the Scotch yoke will prevent friction-causing trust forces acting on the piston skirts, and it offers effective under-piston pumping.

Frits,
Going back a bit to this post and just taking time to try and digest it all, I was thinking that the Scotch Yoke has been around for a long time and seems to work well in many slow speed applications, but I have not seen it applied successfully in high speed operation, wonder why? I'm sure it has been tried often enough.
It looks to me to a very simple acceptable alternative to the normal crank and conrod, but there must be a major obstacle for it not to have been universally used! (lubrication problems?).
I guess the horizontal, vertical and rotary sliding forces involved all get together to cause high frictional losses, but maybe something else as well - got me stumped!

[Frits Overmars]

...I was thinking that the Scotch Yoke has been around for a long time and seems to work well in many slow speed applications, but I have not seen it applied successfully in high speed operation, wonder why? I'm sure it has been tried often enough.
It looks to me to a very simple acceptable alternative to the normal crank and conrod, but there must be a major obstacle for it not to have been universally used! (lubrication problems?). I guess the horizontal, vertical and rotary sliding forces involved all get together to cause high frictional losses, but maybe something else as well - got me stumped!

The Scotch Yoke may have been around even longer than the now-familiar crank and con rod system; I wouldn't know Will. But I've never seen a Scotch Yoke in an engine yet, and I've been around for some time as well.
I agree that it's a very simple alternative, even simpler than a crank and con rod. But that is in theory. I suppose that the main practical obstacles are as I described: either only a line contact between the big end bearing and the slot, which will have insufficient load carrying capacity, or an auxiliary sliding construction in the slot which will add both mass and friction. I guess we will have to wait for Flettner to build it and hopefully prove me wrong.

[WilDun]

The Scotch Yoke may have been around even longer than the now-familiar crank and con rod system; I wouldn't know Will. But I've never seen a Scotch Yoke in an engine yet, and I've been around for some time as well.
I guess we will have to wait for Flettner to build it and hopefully prove me wrong.

Yeah I guess he's game to give it a go - the "suck it and see" attitude which can sometimes come up trumps!

[Frits Overmars]

the "suck it and see" attitude which can sometimes come up trumps!

Sometimes the English language scares me. Are you saying there's more than one Trump?

[husaberg]

Sometimes the English language scares me. Are you saying there's more than one Trump?

Trump card is a winning card in a hand. Not to be compared with the Donald Trump who is a whining cad not playing with a full deck.

[WilDun]

Sometimes the English language scares me. Are you saying there's more than one Trump?

Yes I was thinking as I was typing if the word 'Trump' would bring up Donald! - as Husa says it's a card game term - (you probably knew that anyway).
The English language is not really a language but a compendium of languages (mainly German, Latin, French Norse etc, plus hundreds of recent additions - nothing to do with England any more! - try reading a manual in Chinese English! or a description of a product on Ebay. - or even make sense of the computer trying to tell you that you are wrong if you don't spell it as in 'American' English.

It's just like the two stroke engine! eg.look at the 'KIWI two stroke', it has branched into all sorts of weird things (all thanks to Bucket Racers).

[Flettner]

Yes, Donald Chump, who would have though. Let's see what he will do, I heard him in an interview talking about wind power. He clearly has no idea.

[Grumph]

Yes, Donald Chump, who would have though. Let's see what he will do, I heard him in an interview talking about wind power. He clearly has no idea.

While I'm not a fan of his, this seems appropriate....

[WilDun]

While I'm not a fan of his, this seems appropriate....

Good one ........ but give the guy a break, he does know about some things - like bullshit and wind power (using hot air) and now he's talking up two stroke triples! what next? - definitely a visionary!

[husaberg]

Yes, Donald Chump, who would have though. Let's see what he will do, I heard him in an interview talking about wind power. He clearly has no idea.

They have just sarted on a kite wind farm in Scotland, it actually sounds intersting, when i first heard about it I assumed it was static electricity driven, but it works on a kite more like a wnged parasail moving to power a generator.

http://www.independent.co.uk/environ...-a7348576.html
To be fair though the north of Scotland is bloody windy.

[Frits Overmars]

They have just started on a kite wind farm in Scotland.

Not quite yet Husa. This Oct. 2016 article reads: "One of the world’s first commercial-scale, kite-driven power stations is set to be created near Stranraer in Scotland".
Now let's look at another windy place, the Dutch west coast where dutchman Wubbo Ockels presented his Laddermill, 37 years ago. http://www.drachen.org/article/tappi...-energy-source

[Flettner]

A friend of mine in the US was developing a rotor system for such a Kite (gyro kite) for some big corporation (with lots of money). Power generation from the spinning rotor system, on real long ropes I guess. Supposed to be top secret so I can't say any more about it.

[tjbw]

At first glance I thought that this was a uniflow 2 stroke, with a rotary exhaust valve in the head.

However, I soon realised that it's a 4 stroke, with single overhead camshaft.

I also thought that supercharging could be achieved with the two crankcase compression cycles per power stroke, but I guess it didn't work so well, as it never made production.

Michael Moore just posted these images of this engine on the ESE thread:

Now we can see that it's a four stroke, with reed valve controlled crankcase compression, feeding an inlet poppet valve via another reed valve!