|Railway Preservation News
|Understanding Porta's papers
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|Author:||Nigel Anthony Hewer Day [ Fri Jun 13, 2014 5:06 am ]|
|Post subject:||Understanding Porta's papers|
Reading various topics and threads here Porta's papers and technology come up regularly and even in recent days have been quoted both in and out of context. They are a valuable sorce of information and rightly people read them as such. The deeper meaning of his papers is only learnt when you apply them. Myself I am not one for vast academic writings and I am always being asked to write more, maybe one day. I never saw any of his papers before I started my innovations. I never met him and I am told by other who new him that we would have had explosive discussions on technology, but all for the good.
He wrote the papers to spread the understanding of how the steam locomotive can be dramatically improved and gave that information freely. Reading comments within the papers like' this is not a kitchen recipe' show that he wanted people to take things on as a full concept not just a half harted miss understood mess that is doomed to fail. We know that to do something is better than nothing but he is there to encourage you to apply the lot in one go! So if you do something and it dose not work out you learn what dose not work and what you need to do to make it work better than before. Some of the papers push the limits and people who found issues that needed working on asked him' what do you do about this? His reply was' that's what happened to mine but I wanted to see what you came or come up with as a solution. From this you can take two things from the papers, firstly they are research papers that are not the absolute end of the development of steam technology and that he wants us to continue along that road 'never giving up'. The second is that simply to apply anything without though and understanding not of only what your doing and the risks and beifits to be had and then blame the sorce of the information when it dose not work is not an option. Books will tell you what you want to know not what you need to know. It's only when you actually do something phisicaly that you will learn what's right or wrong and then how to do it better. Hardware will teach you more than any paper even though you can get good ideas of where to go from others writing but they will only tell you what they want you to believe.
It's now something like eight years since Porta died and we all miss him. His legacy is his papers but that is not what he wanted, its to see people apply and understand to go the next stage, phisicaly. I have seen and read many reasons on this page for not doing something positive, it will never stop me. I hope that even writing this has encouraged one or more of you to take the encouragement in Porta's papers and do something posative beyond what he writes about. Now I stand back and watch those who will condemn me and like minded people for doing what we know is right. Don't look back and take on the future and what we can offer to make it better in hardware not BS.
|Author:||Randy Musselman [ Fri Jun 13, 2014 9:21 am ]|
|Post subject:||Re: Understanding Porta's papers|
Recently I purchased the trilogy offering of Portas papers from Camden, mostly for the compounding paper. At this stage in my life time only permits occasional research and dilogue but hopefuly some day before I leave this world, some iron can be cut....to finally get my machine tools out of storage.
As the masses would say, nothing is more noble than supporting a lost cause. Most of the transporation and power based industries would say this about reciprocating engines versus turbines.
As for steam recip engines, in North America, may I suggest the most advanced recip compound in regular service resides in a pair of propulsion engines in the SS Badger. In the midst of a coal combustion system upgrade and the addition of an ash retention system (thanks EPA concent decree) , its an interesting test bed for maintaining heritage technology for daily service......hoping to learn of the "real" steam rate of these Skinners.
Its interesting that J Stumpf aggressively touted the benefits of uniflow over multistage compounds yet Porta as I have seen to date has rarely if ever mentioned the technology, advocating conventional. It appears that high speed recips with healthy streamlined and open porting may suffice.....avoiding all the messy challenges of..barrel shaped cylinder bores, long pistons and very long cylinders.
Looking forward to more study....and later iron.
Thanks for posting and your perspective.
|Author:||mjanssen [ Fri Jun 13, 2014 12:16 pm ]|
|Post subject:||Re: Understanding Porta's papers|
Well said, Nigel.
The traditional (low inlet pressure) compound Unaflow/uniflow engines with 10% exhaust clearance require pulling a vacuum in the exhaust for efficient operation - same need as a triple expansion. A sufficient pressure drop is needed for the steam expansions desired is the objective, however, the 10% exhaust clearance Unaflow/uniflow also needs this to limit compression. Alternatives are a significant amount of clearance volume, or auxiliary (counterflow) exhaust. With 600 psig inlet pressures as Chapelon and Porta suggest for 1970's and beyond steam one should be able to have a sufficient number of expansions exhausting to backpressure with a triple. An area partially explored is the Unaflow cylinder with 25% exhaust clearance. This also makes for a shorter cylinder among other possibilities described in Stumpf's book.
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