The Home Machinist!

Turbine power came up in another thread(which now I can't find!)

The new issue of Classic Trains has a nice feature on the S2 with a good tech descrip. of the mechanism. The article mentions that their website has more info including patent drawings.

OK John, get to work!

Paul

Hi,

Perhaps "Turbomotive Project" is what you are looking for?

Remember, full size turbines are designed for efficiency, so they have multiple stages with rotating and stationary vanes (power stations are good examples). Unless really well designed, a turbine usually isn't as efficient, especially when you are trying to make it perform well with varying load & speed. In a model, we are more concerned with power, so the design needs to be quite different that's why I suggested a single stage turbine wheel.

Richard Trounce

Here are some thoughts but I can't be 100% that they are correct or true. Makes for good discussion though!
Under 300 hp, the steam engine is more efficient than the turbine (McNaughtons Manual). Single stage turbines for driving direct to a start stop machine are of little value. With one set of blades, you can't grab all the power out of the steam before is gets to the outlet of the turbine. Even with a multi stage turbine, from a standing start, a lot of steam flows through before your input/output curves come closer together. With the steam flowing past stationary or slow rotating blades at start, the blade wear would be something too. The Pennsy drove direct to the wheels (one large forward turbine and one smaller reverse turbine) and steam flow (slip) past the blades at start up was inceradible and created wear even with superheated steam. Turbines aren't meant to turn over slowly and the S2 really used up a lot of steam to get the train up to a speed where its turbine efficiency would come into play. The C&O 500's and the "Jawn Henry" turbines drove generators which allowed for a faster ramp up of the turbine if they tapped off the generator to the traction engine motors. (not sure how they were wired)
Also the pressure drain or drop on the firetube type boiler caused heavy staybolt strains due to the pressure/temperature drops. It probably had high temperature losses throught the smoke stack as well during start up. The S2 and the C&O 500's had locomotive style boilers. The upper pressures for these boilers were in the 300 psi range. The N&W "Jawn Henry" used a water tube design which ran at a much higher pressure and could take the strains. The first plant I worked in had water tube boilers that ran at 925 psi saturated steam. When the hydrolizer came on line, the pressure would drop to around 600 psi in a few seconds. Hard on the boiler but no stays to worry about.
Even driving generators, there were problems in other areas which did these engines in.
There have been some good articles in past magazines about these engines. TRAINS even had an article about a Swedish(?) engine with a turbine driving direct to the drivers through a gear box. I wonder if it is still around?

As for the pressure drop and staybolt issues the article goes into that and states:
"...continued to suffer from failed staybolts in the firebox. It was initially thought that the rapid changed in boiler pressure....were the major contributing factor to these failures. However, observation and testing disclosed that a boiler design defect was in fact the most significant contributor"

It really is a good article esp. if you are interested in the S2. Great pics too...

Paul

HaHa, Yeah, like I need another project right now..... A few years ago though I was pretty sure I was going to build one, I even ordered the cast iron blanks to CNC the drivers from. I did a lot of research on the S-2's, but never did come up with anything concrete enough to start making one. Eventually, not knowing if after all the work that needed to be done, if it would even work, kind of turned me off the project..
John

John,

What information did you find?

_________________
Mattaniah Jahn

Matt Corps. Railsystems,
operating on the Manatee Central RR
http://www.flickr.com/photos/62441046@N06/sets/

There is a partially completed S2 project for sale on Discover Live Steam engine classified. If you click on the ad you can go to a link discribing the original and what the modeler has done in great detail. Interesting reading.

Rick

Basically I just found a few photos, and not much of anything else. Then I remembered that there was only one of these things, and it didn't last too long. That being said, I didn't think there would be much information on it. Someone did tell me that the PRR archives in Harrisburgh has the prints..
Are you planning on building one?
John

I'm helping a friend source prints so he can build one, my next build's going to be a PRR J1. I sent off for both drawing indexes, can post an update on my findings if you want.

_________________
Mattaniah Jahn

Matt Corps. Railsystems,
operating on the Manatee Central RR
http://www.flickr.com/photos/62441046@N06/sets/

There were some model drawings of it in the old Model Craftsman.

Is that a book?

_________________
Mattaniah Jahn

Matt Corps. Railsystems,
operating on the Manatee Central RR
http://www.flickr.com/photos/62441046@N06/sets/

I'd love to hear your updates.. The Pennsy J-1 is one of the locos I'd like to build one day....
John