For the funky engine configuration fans here on Oppo...

"RamblinRover Luxury-Yacht" (ramblininexile) 08/01/2016 at 10:55 • Filed to: None

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May I present - the !!!error: Indecipherable SUB-paragraph formatting!!! Dynastar:

It was similar in principle to the so-called “twingle” used on Puch motorcycles, and !!!error: Indecipherable SUB-paragraph formatting!!! .

Jcarr > RamblinRover Luxury-Yacht 08/01/2016 at 11:06

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I’d be concerned about the gaskets.

#toosoon

RamblinRover Luxury-Yacht > Jcarr 08/01/2016 at 11:09

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Running a two-stroke engine on rocket fuels is the best idea ever.

Jcarr > RamblinRover Luxury-Yacht 08/01/2016 at 11:18

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Worked pretty well for Hagrid.

Cé hé sin > RamblinRover Luxury-Yacht 08/01/2016 at 11:31

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There’s usually a reason if something doesn’t go beyond prototype stage....

RamblinRover Luxury-Yacht > Cé hé sin 08/01/2016 at 11:39

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Purportedly their prototypes were working well enough in both diesel and gas configurations, but one of the worries was related to emissions - a two-stroke with a very large amount of internal surface area and one cylinder which operates mostly as a compression pump and valve for the other is apparently not a good recipe for clean running. That, combined with a limited market for bulky industrial two-strokes that are limited in revs, and it’s not really a mystery, even leaving out whatever maintenance issues might have cropped up.

MrDakka > RamblinRover Luxury-Yacht 08/01/2016 at 12:17

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Why, still doesn’t have the sheer funkiness of cam/swashplate/wobbleplate engines

RamblinRover Luxury-Yacht > MrDakka 08/01/2016 at 12:24

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You’d think that being less funky than a swashplate engine would be enough to succeed, but apparently not. Swashplates are in use in torpedos and elsewhere, this, not at all.

jimz > RamblinRover Luxury-Yacht 08/01/2016 at 12:26

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looks to me like it’s a modification of the aircraft radial engine design, but instead of having one master connecting rod to which the rest of the rods... er.. connect to, they use a single plate for all of the rods.

One of my favorites is the Napier Deltic family. Three sets of opposed piston, two-stroke:

and yes, this actually existed for years as a marine, generator, and rail powerplant.

MrDakka > RamblinRover Luxury-Yacht 08/01/2016 at 12:41

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True enough

RamblinRover Luxury-Yacht > jimz 08/01/2016 at 12:43

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The Dynastar’s use of inter-rod connecting rods isn’t totally unusual. Most radials use a central thrust ring/plate thingy, but not all - I’ve seen a pic of one that had a mini-crank for each cylinder. *That* is wacky, this not so much. I’ve seen an inter-rod linkage system on some experimental setups for quasi-rotaries and other weirdnesses as well.

I’m well aware of the Deltic. One thing that does raise my curiosity on the Deltic that I haven’t researched further is that the inlet ports are doubled - one on either side of the cylinder. Was the forced induction controlled by - rather than wastegating - allowing over-blow into the secondary galleries and throttling that?

jimz > RamblinRover Luxury-Yacht 08/01/2016 at 13:19

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I don’t think so; I believe it was just a matter of ensuring consistent airflow into the cylinder around its circumference. if it was only on the one side of the cylinder like the exhaust outlet, then incoming air would hit the opposite cylinder wall and have to make a hard “turn,” which would reduce exhaust scavenging effectiveness. they didn’t have to worry about the exhaust ports going around the circumference because they were just trying to “push” it out into the manifold.

even small two strokes with a single piston work similarly; ones designed for performance will have 2, 3, 4, or 5 inlet ports with a Schnuerle (loop scavenging) design, and a single exhaust port.

Cé hé sin > jimz 08/01/2016 at 15:10

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They had three or six element versions so nine or eighteen cylinders. Some are still in service.

Not complicated enough? Napier investigated the possibility of a square version with four sides.

Cé hé sin > RamblinRover Luxury-Yacht 08/01/2016 at 15:12

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Top trivia: the secret to making the Deltic run properly was to run one of the cranks in each element in the opposite direction.

Cé hé sin > RamblinRover Luxury-Yacht 08/01/2016 at 15:17

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I’m reminded of that other great white hope, the Achates opposed piston engine, which has been promised for years without ever actually appearing.

RamblinRover Luxury-Yacht > Cé hé sin 08/01/2016 at 15:36

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I think I recall from the four-crank version that two of the cranks ran one way, two another.

Cé hé sin > RamblinRover Luxury-Yacht 08/01/2016 at 15:42

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That would make sense, in so far as anything on a Deltic made sense.

More trivia: each cylinder fired independently which probably helped with smooth running (the reason they were used on minesweepers).

BringBackTheCommodore > Cé hé sin 08/08/2016 at 11:52

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Ooh, funky gif for funky engine configuration. Nice!