A little more progress
Latest work on the Fowler involved replacing the chimney on the smokebox.
The saddle now has a fibre glass tape gasket to seal it against the smokebox and better fitting bolts.
There are brackets fitted to the mixing chamber and some of the smoke box saddle bolts to ensure its kept central.
There is no news on the nozzles.
I also refitted the right side eccentric rods uncrossed and the lower rod on the left side, that is after fitting the rebushed rocking lever.
The eccentric rods were previously crossed.

Nigel asked me to post this instruction for aligning the mixing chamber with the blast pipe and I have included the latest photo of the Blast pipe and mixing chamber.
Unfortunately I am still waiting for the nozzles to be machined but I am told they are being done.

I have just joined the forum and have been reading through this thread. With respect to setting the angle between Lempor nozzles I thought this page might be of interest:

http://www.michaelguy.ca/lempor%20updat ... 20page.htm in part, it shows a graphical method of setting the angle suggested to me by Jos Koopmans.

For background, I am co-author of the Lempor calculator but all my experimental work was on 7-1/4" gauge miniature locomotives, not full-size.

Cheers,
Michael Guy
Toronto.

Koopman's method of determining nozzle alignment is WRONG for a proper 'Porta' type Lempor ( see Wardales book 'The Red Devil' for details)see the sketch on page 2 of this thread showing centre line aimed near top off mixing chamber at 7.25 degrees.

This thread is about doing a Lempor for Dennis to get the Fowler steaming, nothing more.

Dear Mr. Guy

Thank you for the link.

Sincerely,
Robby Peartree

Robby: Thank you.

Nigel: How nice to hear from you again, it has been a while. I have two comments in reply.

1/ Porta continued to work on locomotive draughting until his death and he certainly didn't consider the Lempor to be the last word on the subject so there is no such thing as a "proper" lempor. The only proper Lempor is one that works as well as he expected.

2/ I have conducted my own experiments and am satisfied that bouncing the exhaust streams off the mixing chamber walls with an excessive inter-nozzle angle is counter-productive. It may work well enough at slow speeds but once the locomotive is throttled up and road speed increases, the flow in the diffuser becomes so confused and turbulent that the system chokes itself and vacuum production flatlines. If the four nozzles are each lined up with their respective quadrant at both the bottom and top of the diffuser in use, vacuum does not flatline it continues to increase with increased exhaust steam flow right up until the maximum rpm of the engine in question is reached. Try it if you don't believe me.

Cheers,
Michael.

Participants on this thread take note I started this thread asking for information regarding Lempor Nozzles to which Nigel was good enough to respond .

I did not start it for any of you to start bun fights with Nigel with your own views on Lempor exhausts.
I will have no hesitation in directly corresponding with Nigel regarding results when testing begins and how the locomotive performs hauling regular trains.

If you want to dispute modernised draughting systems and wish to spread your own thoughts start another thread.

Its up to you.

Dennis

Well please pardon me for interrupting your private conversation on a discussion board.

Robby Peartree

There's a large difference between experienced experts discussing their results from different adaptations, and mud flung by people wo haven't the knowledge or experience to make their opinions worthy of being shared, though it doesn't stop them from imposing it on all of us anyhow. I think this belongs in the first category, and I would welcome factual discussions from Michael, John, Nigel, Jos and anybody else who does know what they are talking about as to how their experiments have worked and where they agree and differ. We all have a lot to learn, and I don't think Nigel would presume he is the final word - he seems to respect further development and is doing so himself.

Please do not discontinue a good discussion among experts about this fascinating subject. Feel free to lambaste and delete posts by uninformed foamers.

dave

+1.

I know that Ing. L. D. Porta himself personally e-mailed me when he was alive and asked for my help in getting his Lempor Theory document out to the world and that he specifically requested that people (hopefully those with practical or theoretical knowledge) review his work and provide comments (good, bad, or indifferent) so that he could improve his understanding of exhaust systems. If the man who developed the exhaust and the theory to explain it asked for input on his work, it is only following the spirit of his work to continue the discussion.

Michael and Nigel disagree about one aspect of designing a Lempor; there's no reason the discussion can't continue.

Mr Guy
I did what you say some 20 years ago and found it wanting so I dont belive you. Nor do I belive from the little contact I have had with Koopmans that he understand the impingement, mixing and boundry layers which are the foundation of the work of Chaplon and up to Porta and beyond. If you wish to offer a difrent opinion then fine, but I have no intrest in such a debate in words on things I have long since delt with in hardware. There is much people dont know of what I have done and understand which I will keep private, so please dont asume anything about me. In the route of all this is the reason I keep my own work private for fear of miss understanding by others.

I say again that I contributed to this thread for the benifit of Dennis and was happy to allow it be public for all to understand what I am about. The aim was to prove in hardware NOT words Portas work and the benifits to be had from it. I am aware of another site you and Koopmans yak on about front ends and such matters and that is the place for your debates but dont drag me into it.

I will finish off the work with Dennis in private and only then decide if? we wish to make it public. What ever I will not sink to a bun fight over such matters.

Bun fights don't interest me in the least nor do "secret" and "private" solutions to problems of interest to all of us. I put my own work, such as it is, up on open web pages hoping for discussion, feedback and progress.

As it stands, I am happy to enter discussion either here or off-list with anyone having questions about either the calculator or how to design a lempor exhaust for themselves based on only my own knowledge and (I admit) somewhat limited large loco experience. Having said that, it is beyond question that tests and experiments with "models" are used worldwide to control conditions and reduce costs and the results scale up reliably. I have complete faith in my own conclusions but infallibility is not given to man.....

The design process I use is this:

1/ Use the calculator to size the nozzles and mixing chamber for a given engine. This takes all the sweat out of Porta's complex calculations. You do need to know what draft rate you want at the grate .

2/ Design the diffuser according to known principles as sketched in on my web page referenced earlier and with reference to Porta's paper.

3/ Use a drawing program to graphically set the inter-nozzle angle which will also position the nozzles vertically with respect to the bottom end of the diffuser. This will disclose the length of the mixing chamber, again, reference the same web page for illustration. Rote use of an inter-nozzle angle designed for use with some other diffuser than the one you are using will almost by definition be wrong and produce disappointing results.

4/ Once the nozzles, mixing chamber and diffuser are fixed in relation to each other, the whole assembly can be located within the smokebox. Adjustments will then need to be made if the system doesn't fit. This may require re-doing the diffuser proportions, i.e. a tall diffuser will have a narrower angle than a shorter one. Making it fit by altering the nozzle to diffuser distance alone is incorrect, the angles are inter-related.

5/ Although not strictly necessary, one can finesse the nozzles with the square design and Goodfellow tips. I doubt this will show any big advantage for small engines ambling along but should in a bigger machine running at relatively high speed.

I rather enjoy the design process and the calculator allows one to run multiple iterations for different conditions very quickly without spending hours on the math. Juggling the diffuser proportions to fit the particular locomotive can be a challenge requiring several attempts but if the key dimensions of nozzle diameter and diffuser throat diameter are maintained and the guidelines above are followed, an exhaust can be built that will work "right out of the box".

If the above is of use to you, great; if not, just ignore it.

Regards,
Michael.

I believe that's what most who read here would want, an "Out of the Box" Lempor arrangement without the work involved. Personally I find it fascinating and this has piqued my interest in applied math once again. I probably speak for a lot of people who do not post but we would all like to see a continued discussion.

Mr Moderator and silent readers

This thread has been hijacked and is now at an end.
Thank you and good bye

I rarely post anything on this site, but take great interest in such technical postings such as this topic.
I would appreciate if we could continue this topic for everybody, perhaps if persons have different view they could open a new topic page?
Thanks to the original poster for the excellent information should they choose to close the topic.