Orbital – Not your Usual Oscillator!

[duncan webster 1Participant @duncanwebster1]

Wikepedia is more readable. Note it says secondary imbalance is at twice the frequency of crankshaft rotation and so agrees with Swanson.

Horizontal flat engines (or flat anything I suppose) have primary and secondary balance as long as they are boxers

[Michael GilliganParticipant @michaelgilligan61133]

If we must improve Jason’s lovely little engine … I would have thought a flat three version would be near perfection.

[brought to you by instinct, not hard-sums]

MichaelG.

 

[JasonBModerator @jasonb]

As I said it is the smoothest running of the dozen or so small wobbler and slide valve engines that I have made including a vee twin so I’m not in any hurry to make a Mk2 but look forward to seeing other members versions.

Just look back through some of the videos I have posted if I’m not holding them down to stop them levitating across the bench they are either held in a vice or double sided taped to a big bit of metal. None of which wa sneeded with this engine.

It is a bit like putting a piece of work off ctr in a small chuck and the same piece in a large chuck, one will vibrate the lathe the other won’t. Having a relatively large flywheel and the counterbalance weight tends to smooth things out a lot. As I said going to double acting would smooth it out even more as you have a power stroke in two directions rather than one.

Here is a blown up view of the engine from above. Purple are the ctr lines of the axis of rotation. The circle with two black quarters and two clear quarters indicated the ctr of mass. Less than 0.2mm off at mid stroke and it’s a lightweight all aluminium piston & integral rod so not much change as the piston goes up and down.

[Author]

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