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| Gas Firing the Scott Vacuum Engine.......... |
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| SwarfnStuff:
He, he, well I shall just have to have another :coffee: or two. OR, I could do some more messing about with my attempt at Jan Ridder's Coffee Cup Stirling. Blimey they are fiddly, got it to run in a lumpy fashion then fiddled some more to (Improve it) and it refused to go. Next, after a pull down, fiddle, bung it back together and it ran anti clockwise (had timing offset 'tother way round) but also ran lumpy. Being about 1/20th of a mosquito power, friction and balance are the enemy. Taking it to my local Model Engineering club tomorrow to see if the chaps have any idea of what I'm doing wrong. I agree with OZ that the 45 deg angle of attack looks good. That said, looking again at the two flames the 90 deg just might be easier to set below the snuff out zone. John B |
| Stilldrillin:
OZ. Thanks for the boost to my confidence! Which has now, just suffered a big knock. :palm: See further down page........ John. A few more coffees to come,as yet........ I hope your coffee cup stirling, is now running like a good 'un! :thumbup: I wonder why many, start with a coffee cup, or pifflin' tiny engine, with little power? :scratch: I started with Gold Blend. So big, it had to run! (And, still does). http://madmodder.net/index.php/topic,5732.0.html Anyroad! I've had one of those moments......... An epiphany....... When you realise, you've had it all wrong. For so long........ :bang: Yesterday's workshop weather, bit me. Staying in, today. Chance to test the various burner angles....... Only place available, is on top of a wardrobe. At forehead level. Mrs. Drillin doesn't complain too much, about gas smells...... :( All the various terminals performed, exactly the same as each other! Always, the blummin light, blew out!!! :bang: :bang: Standing where I was. Looking up at the burner. Never observed from this angle before....... The light's not being blown out....... It's being sucked out!! Very difficult to photograph. But, obvious to the Mk1 eyeball. The intake velocity is greater than the gas velocity........ Puts a whole new slant on things, don't it? :scratch: Sheesh! David. |
| Manxmodder:
All seems so bleedin' obvious now you've seen the problem first hand :doh: I'd wager that the solution may not be quite so easy to arrive at. Time for a bit of further experimentation methinks :scratch: ....OZ. |
| Stilldrillin:
Thanks OZ. :thumbup: You're right! Here we go! My thoughts, are now running along the lines of a soap bubble. Easily taken from it's ring. Mod the orifice, to make it less ring like. Milled a 4mm slot, in the 5mm bore terminal....... Burns well....... Cam follower bounce, at full blast....... But. That's not what we're here for! I need it to run reliably at around 150rpm. And, wind up, as necessary. Sleeved down, to a 3mm orifice....... No! ...... Not enough gas! Needs a larger bore terminal. The one thing this has proved. It works perfectly well, when the burner is outside the shroud. The vacuum kills the flame, when under the shroud. I'm now steeling myself, to remove the sides, (or all), of the shroud. Without any collateral damage to the polished cyl head...... :palm: David. |
| Manxmodder:
"Cam follower bounce, at full blast"....... :bugeye: I guess Desmodromic valve gear is out of the question :) :) On a sensible note maybe just a couple of holes drilled in the sides of the shroud would be enough....OZ. |
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