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Post by jhaines on Jan 31, 2007 10:17:28 GMT
Can anybody give a guesstimate of the typical flywheel rpm expected of a 3" TE, I've worked out some gear ratios for a 3" Durham and North Yorkshire but really need an idea of expected flywheel rpm to work out how fast the thing will go, or alternatively the right gear train to get a suitable end speed, I'm guessing about 2mph low and 4 mph high?
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Post by alanstepney on Jan 31, 2007 12:18:33 GMT
Full size typically run at 160rpm, if that is any help.
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jackrae
Elder Statesman
Posts: 1,335
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Post by jackrae on Jan 31, 2007 12:23:56 GMT
I cannot answer your question directly but scaling flywheels when useful work is required is a bit of a compromise
The engine is scaled in a linear relationship but if you scale a flywheel similarly then the inertial effect is scaled to the 4th power (ie by a factor of 16)
This can be partially negated by running the engine RPM at a higher speed than the fullsize model.
Alternatively, if you can lay your hands on a lump of depleted uranium - there's bound to be some lying about somewhere - -------
Jack
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Post by albertsell on Jan 31, 2007 19:36:07 GMT
I have built six traction engines some to my own drawings. As to gear ratios I have found that if the high gear is around 9 and low around 15 this gives a good road speed and also a good slow pottering around speed. (do not use lower ratios) As to crank shaft speed 200 RPM can be achieved quite easily if the crank shaft balancing is good.
Nice to know some one else is interested in other than locos.Have built 8-3.5 &5ins locos.
Albert
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John Lee
Part of the e-furniture
Posts: 375
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Post by John Lee on Feb 1, 2007 18:02:08 GMT
I have built six traction engines some to my own drawings. As to gear ratios I have found that if the high gear is around 9 and low around 15 this gives a good road speed and also a good slow pottering around speed. (do not use lower ratios) As to crank shaft speed 200 RPM can be achieved quite easily if the crank shaft balancing is good. Nice to know some one else is interested in other than locos.Have built 8-3.5 &5ins locos. Albert I think you will find most people are very interested Albert; Traction Engines are a very close relative to loco's. The problem is that size wise, a 2" scale is the minimum if you want a realistic hauler, and then you have the question of workshop facilities in the average home, unless you want to buy in gears, flywheels, wheels etc at relatively huge expense. I did a 1 1/2 Alchin, but its sits on a shelf, a beautiful design but..... Do please post more, if there are workarounds I am sure the "steam mad" on here will be interested. You don't need tracks for one!! John |
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Post by spurley on Feb 1, 2007 19:25:08 GMT
Hi there
I have got to agree with John about Traction Engines, I have the castings, gears and a boiler kit that I bought for a Minnie. The idea was that I could fit the parts onto a small(ish) lathe easily and still build a steam engine that would 'go' without requiring a track to run it on. However things have developed for me since I joined MESNI (see below for translation!) they have great track facilities and I find myself there at least twice a month now when I'm home.
I will build Minnie when I finish my Tich and that way I can still steam at home if I don't fancy the 50 odd mile round trip to Cultra!
Cheers
Brian
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Post by greasemonkey on Feb 1, 2007 22:13:53 GMT
Hi Albert
A traction engine is on my list of projects to build but Ive got enough on my plate at the moment, one day though! A nice 4" will do.
Andy
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Post by Steve M. W on Feb 1, 2007 23:32:16 GMT
Hi Albert
A 4" Burrel is on my list I have the drawings, your not alone Keep posting.
Steve
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Post by Nexuas on Feb 2, 2007 12:02:18 GMT
Me too. I want to build/buy a 4" scale traction engine, but at the moment I do not have the factilities to build this or the bank balence to buy it, but it is definiatly on my list!!!
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Post by jhaines on Feb 2, 2007 12:50:13 GMT
Thanks for the comments, still a little vague on the flyheel rpm though, I note from the Bailey steam website that the full size Ruston he is building will be running at 350rpm!
After the 3" TE I may want another project and wonder about a freelance wagon (or waggon!) to see how simple a large model could be built. A large steel vertical boiler with a twin cylinder engine slung under the chassis.
Food for thougt.
10" rubber tyred trailer wheels
twin cylinder ex motor cycle block crank , either retain valves or new head .
ride on lawn mower differential,
As long as the thing was sympathetically bodied and acepted as a bit of robust fun then I see no real problem.
More ideas welcome, perhaps started as a second thread?
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Post by Steve M. W on Feb 2, 2007 13:17:48 GMT
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Post by albertsell on Feb 2, 2007 20:09:25 GMT
My first T/E was a 3ins. scale Burrell which is about the same size to a Durham and N/Y, that would travel on tarmack faster than it was safe to travel, so I would not trouble yourself with flywheel speed. My 3ins. Fowler is just the same. Both these engines plus my 3ins.Minneapolis have done the 11miles road run at St. Agnes.
Nice to know there are others in the group interested in road steam.
Good steaming Albert.
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