# Jack, the large scale DeWinton



## deWintonDave (Jan 5, 2008)

Dear All,

Large scale Jack our latest DeWinton loco was hauling a short train the other weekend. Here's some shots of the loco raising steam - it takes a while.




























Here's a video of the run: 

http://www.youtube.com/watch?v=LNQcoanpK18

Last year the leaky whistle valve was fixed with an O-ring. And, a new whistle was made - the biggest I could fit under the footplate. The driver is quite heavy on the whistle... 
I know some don't like oscillating cylinders, but these just gracefully walk along, they don't need to whirr away at mach 1. If you keep the cylinders hot there's no condensation, and a single-fill of the boiler lasts a long time.


Best wishes,

Dave.


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## HMeinhold (Jan 2, 2008)

Dave,
a very nice model! Did you base it on Dave Watkins Idris or is it your design? I agree with you about the speed/condensation relation. This is probably the reason, 1/2" cylinders are so much superior to 3/8" (Better surface/volume ratio and more time to fill) . What do you think about a heated cylinder jacket?

Regards


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## xo18thfa (Jan 2, 2008)

Gorgeous engine Dave. Could you layout some more technical details. Bore, stroke, boiler type, fuel

Thanks, Bob


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## lotsasteam (Jan 3, 2008)

Fantastik engine! Any plans available? These quarry engines have a flair of their own!!! 

manfred


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## deWintonDave (Jan 5, 2008)

Thanks guys! Yes, the engine is based on Dave Watkins' Idris plans. His plans are available on his webpage

```
http://www.davewatkins.pwp.blueyonder.co.uk/16mm%20railway/steam.htm
```
. 

I scaled-up the plans from 16 mm scale to suit the 45 mm track. Like on my second loco I raised the cylinders up to the level of the top of the boiler. My secret is that the port block is directly soldered on to the boiler shell. This eliminates condensation and lowers water consumption. The run on the video was over 1 hour 20 mins. I think that it is more efficient to directly heat the cylinders than to expect steam to perform the heating and powering. 

The second departure from the plans was to "stroke" the motor to the maximum extent, my thinking was that it would slow it up and make for more pulling power. The exhaust is lead under the boiler and the nozzle is about an inch below the flue to draw the fire. 

There are many construction photo's in the photobucket album

```
http://smg.photobucket.com/albums/v453/bouser/Jack/#!cpZZ3QQtppZZ16
```
. The boiler is a single flue, with lots of protruding copper "spikes". it is fired by alcohol. 

Best wishes, 
Dave.


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## HMeinhold (Jan 2, 2008)

Dave,
my remark about heating the cylinders with steam was not geared towards DeWintons or traction engines, where you can bolt the cylinders directly to the boiler. Of course, this is the ideal situation and prevents condensation almost completely. My friend Eric has a traction engine with bolted-on cylinders, which can tick over very slowly. I was thinking about "normal" engines, where the cylinders are far away from the boiler. Locos run very slowly on air, but under steam it is a different story. Below a certain speed torque drops rapidly to "0" due to condensation. This gets worse with increased area/volume ratio.

Regards


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## xo18thfa (Jan 2, 2008)

Dave: Thanks for the link to the builder's photo's. What a great job overall. I think using alcohol fuel is a good choice. Your tank is wide and long. It will keep a good fuel level to the burner pots during the entire run.

vr Bob.


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