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Monty Python would have called this the ministry of silly engines

Posted 9 years ago

I hope the title grabbed your attention, now do please open the attachment and you will see the analogy. I have been working on this project of a rotary aero engine (circa 1908-1920) for a few weeks but seem to gone astray with the math co-ordinates for the rods, pins and pistons. So I am now opening it up to you good folk on the forum who may wish to collaborate, educate or fix my addled logic. When the brain is scrambled a second, third...nth opinion,may often see through the cloud.

It is actually relatively simple to make in wood and perspex but am trying to drag the animation into the 21st century.

This chap's site (done in animated CAD) shows the geometry I am trying to achieve in 3D.

enter image description here

3 Replies
Posted 9 years ago

Thanks for your posts, yes have seen the headline radial demo it and it was in fact the inspiration for something to use as an educational display in a museum, next to some WW1 aeroplanes/engines, in fact I confess that I learnt most of what I know from that work by Yu-Sun Chang. The geometry for the rotary is far more complex since there are two centres of rotation. My thoughts were that by using the one known angle at the centre, taken from the animator, I could use the Sine law and then calculate polar co-ord's. (The length between the centre of rotation is fixed and so is the length of the con-rod). But in practice the geometry does not seem as straightforward as I had expected, with a bit of practice the graphics are relatively simple (mainly a bunch of cylinders) once the geometry is done. The logic seems to work well enough in a spreadsheet calc but maybe I am not interpreting the animator output value correctly, its strange that some bits work fine but others are throwing wrong, but consistent, values.


For readers who missed the subtle link, see .

POSTED BY: Bruce Miller

Have you seen this, maybe adoptable?

enter image description here

POSTED BY: Sam Carrettie
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