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Post by GeorgeRay on Aug 23, 2004 19:07:56 GMT
I have got to the stage where I am about to bore the chimney for my Brighton Maisie and thought I would try and incorporate the Swindon draughting arrangements. Having reread Bert Perrymans article I am finding it difficult to make sense of the size for the blast nozzle. With a 17 sq in grate area the chimney choke diameter works out at just about 1inch, according to the article the blast nozzle should be 1/2.8 to 1/3.2 of that. This makes it about 3/8in which seems to me to be way to big. I haven't been able to find any correction to the article so does anyone know where my calculations are going wrong.  |
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Post by GeorgeRay on Sept 6, 2004 18:25:04 GMT
Come on guys, has no one used the Swindon Draughting article for working out their blower and blast pipe size? The original article was published in M.E. in 1978. I am wondering whether the diameter for the blast pipe size should be choke radius divided by 3 rather than choke diameter can anyone confirm this.
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Post by Malcolm on Sept 6, 2004 20:06:54 GMT
George, don't take Perryman's formulae as being holy writ. After his article, there was a lot of discussion in ME. There were references and useful info in ME's 1 Sep 78;17 Nov 78;19 Jan 79;6 Apr 79; 6 July 79; 5 Oct 79; 2 Nov 79; 15 Jun 84; 21 Jul 89 and 18 Aug 89. All are worth reading before you cut metal. There is also a useful reference on P18 of Martin Evans' book "Manual of model steam loco construction" Happy reading!
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Post by alanstepney on Sept 7, 2004 2:54:37 GMT
Jos Koopmans from the Netherlands has done a lot of work on draughting, and has written an article about it, which you can find below, www.alanstepney.info/page11.html |
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Post by GeorgeRay on Sept 8, 2004 12:22:09 GMT
Thanks my index didn't cover the post bag items so I couldn't find the follow ups to the original article.  |
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