P2 Locomotive Company and related matters

I don’t disagree, but this is an important document, key to the P2 project, and is far more informative than anything I can find on the website as it now stands.

IMHO it therefore deserves to be maintained and made readily accessible to those seeking to understand the project, as demonstrated by the questions being raised on here, where it provides many of the answers.

I thought I was well versed in the history of the project, but reading this brought back to mind several facets that had slipped from my memory.

 

I meant that work started on modifying 5399 in 1939.

 

550 rpm would correspond to Mallard doing 130 mph. 'Nuff said?

 

What do you envisage in the way of maintenance of that document? Changing the content to reflect changes in the design since it was written? Maybe nothing described there has changed.

 

I’d disagree that “it needs to be maintained”. “Preserved” as a record, but not maintained (in the sense of being constantly updated).

It’s written in the future tense, ie it is “we will need to address these issues”. As such, it is a useful record of what thinking was at the time, and something you can reference back to ensure things are developing as outlined (or to understand where / why there are deviations). But I don’t think it is a document that you would “maintain” in the sense of updating as you go along.

Tom

 

If you read the paper to the ILocoE, there seems to have been considerable scepticism about the validity of some of the testing, missing data and comparisons for 5399 (e.g. mods to the steam circuit upstream of the valves) plus the usual engineers' suspicion of being sold snake oil. Poultney cited a New York Central Pacific with piston valves which had produced a lower loco weight to ihp (4,725hp in that case) ratio (it is not just on NatPres that people make unsupported statements!). Holcroft also had quite a lot to say and thought that the improvement to the steam passages of 5399 was a major factor. One might note that the author was never going to get an easy ride with Bulleid in the chair as president, who took execption to the description of the indicator diagrams. Notwithstanding, 5399 (and the K4S' class in general) seems to have put in some impressive performances including producing 70,000lbs of steam per hour.

 

T1s were timed multiple times at speeds over 130mph by an observer from Franklin. A T1 had 2-3x the power of an A4, even more than a Big Boy.

 

T1 is quoted at 64,643 lbf and BB at 135,375 lbf on wiki.

A4 is 35000 ish isnt it?

 

96 sq ft grate.

 

Sorry, I was meaning neither to challenge nor to endorse any claims of how fast they went. I meant only to suggest that operation at 550 rpm is far faster than the new P2 will ever need to go.

 

Mr Chapelon had a lot of expirience with poppet valves and chose piston valves for his last significant steam-locomotive 242A1 in 1946.
What new wisdom tempted the P2 revival group to decide on Franklin B?

 

From here: https://www.trains.com/trn/railroads/history/pennsylvania-railroad-t1-technology/

'The Pennsy tested a T1 at its plant in Altoona against one of its M1a 4-8-2 Mountain-type locomotives. The M1a and T1 had the same weight on the driving wheels. The T1 generated 6,552 hp, which was 46% more than the M1a. That is also more than the 6,300 hp put forth by the Union Pacific Big Boys. The T1’s goal was to haul 800 tons of passenger train at 100 mph on level tangent track, requiring 2,838 drawbar horsepower at 38 mph. The T1 generated 6,000 drawbar hp above 55 mph, giving the railroad the confidence that a T1 could out perform a four-unit, 5,400-hp EMD FT diesel at any speed over 26 mph.'

Unlike the Big Boys, the T1 were passenger locos and weren't designed for high TE.

 

Yes, the main advantage of poppet valves is higher power at high speed which wasn't really a requirement of the original P2s. Time will tell whether they have made the right decision.

 

Flow area?

 

Ok, I’m not that familiar with webpage speak.

But AFAIK this is still the design basis for the A1 Trust’s P2 build project (unless anyone else knows differently?) and is therefore totally relevant still today, as it’s not been altered or superseded in any way? If it were to be, then surely such design modifications should be documented as revisions to this page, not as a clean slate?

I think the header text ought to reflect this, and to contain some words in tribute to their late engineer, without whom the project would never have got off the CAD screen.

 

AFAIK The 'products' available to Mr Chapeleon were not ideal, and he never applied his accumen to improve them , certainly never used a rotary drive poppet valve on his locomotives.
Anecdotally it wasnt until the 1950's that versions of poppet valve gear were developed that were a general improvement on conventional gear/piston valves, at which time he was no longer active in the field.
If this development had not taken place i doubt very much that the P2 would be being built with this arangement.
You can argue that psiton valve arragements have also moved on, certainly with todays computing power and simulations the geometry and settings of 'conventional' Piston valve gear can also be improved though this has to my mind not been actively considered by any new build group ( though David Elliott was certainly mentally chewing over a redesign of the conjugated arrangement on the proposed V4) .

 

Frankly it would probably be better if they didn't include the text at all.

It looks to me as though the entire 'educational resources' section is currently beyond the Trust's ability (or is not sufficiently valuable for them to divert time and energy) to actively manage it – probably something about building and running locos rather than running websites…

I've not looked in detail, but it seems as though it's harder now to find https://www.a1steam.com/educational-resources from https://www.a1steam.com/ though, where they could probably have just put an 'archive' or similar link on there somewhere to help people find it. I'm partly with @Sheff on this that it looks like interesting information that has value to some people… orphaning it from the rest of the site seems weird (weirder than the message about it being unmaintained).

In general though, I also see where the Trust are coming from… every page on a website needs to be actively managed. You should invest more time in the pages that are more used and valuable at the expense of information that's seldom used and doesn't perform a useful function for the organisation. Ideally you spend something like 80% of your time managing existing content, and 20% max on adding it. People often tend to approach it the other way around, and quickly end up with more bumpf than anyone can realistically keep up to date, and I suspect that's what's happened here.

Simon

 

Wouldn't the "educational resources" come within the remit of a charitable organisation though?

 

Given they seem to have outsourced one and given up on the other, I wonder what their key activities are now.

TBH, whether the page is archived or not, or even placed on display in the bottom of a locked filing cabinet stuck in a disused lavatory with a sign on the door saying ‘Beware of the Leopard', it's the fact that the key philosophy documents for one of the most important parts of the P2 are at very best parked.

 

I found this from here: https://prr.groups.io/g/PRR/topic/t1_poppet_valve_issues/90638011

'Reviewing the correspondence of the day suggests that it was the oscillating cam mechanism of the type A poppet valve design that suffered from failures at higher speeds, and it is very clear that mechanism, not the poppet valves themselves, became a maintenance headache.

The oscillating cam mechanism was in a separate box adjacent to the cylinders. The internal mechanism was ridiculously complicated - somewhere between a Swiss watch and a Rube Goldberg like contraption.

Conversely the type B rotary cam mechanism was much simpler and quite clever. It was driven by a drive shaft off the driver (hung outboard of the main rod), and drove what was essentially a rotating cam shaft very similar to an automotive cam shaft, but with a sliding mechanism the slid a variable cam lobe across the valve's roller to adjust valve open duration (cutoff in steam locomotive terms), that even included a reverse section. Mechanically a much simpler, robust construction - effectively a very "elegant" design.

After 6110 and 6111 were built with Type A and started encountering problems, starting in 1943 the PRR worked to convert a K4s with the type B design using a welded steam chest and cylinders (built up by welding as opposed to cast), but it was delayed repeatedly by wartime material shortages, and wasn't completed in time to inform a selection for the production T1 fleet. So the PRR stuck with type A for the production fleet (5500 through 5549.)

Eventually they got the K4s with type B working, and it worked well, while the production T1's were struggling with Type A reliability. After 5500 was involved in a serious side swipe (pictures posted here a few months ago), the PRR refit 5500 with type B Franklin equipment, and contemporaneously, but not well documented, 5500 was considered the best of the production T1's, being much more reliable. Problem solved.

Post war the D&H and C&O also bought Hudson class locomotives with the Type B poppet valves and did not encounter any problems, although it is doubtful either RR could run their Hudson's as fast as the PRR could run the T1's out on the west end of the system.

The T1 Trusts 5550 will have the type B, having found suitable documentation about the type B design applied to T1 5500 at the state archives, at the PRRT&HS archives, and from a private collection.'

I wonder if the A1 Trust are in correspondence with the T1 Trust? Hmmmm...