P2 Locomotive Company and related matters

But you know the answer to that already

 

It is quite hard to avoid the impression that some whose loyalties and affections lie with other companies and regions are wishing that this project had never started. 43,684 lbs tractive force, 80 tons adhesive weight and 3,400 hp are all probably good reasons why. There are going to be some grapes and they will undoubtedly be sour to some.

 

I recall Mark Allatt saying at one of the roadshows "despite what fans of certain red engines say, this will be the most powerful steam locomotive in the UK - right, David [Elliott]?"

 

Wrong, and if he wants to prove it is, he will need to produce the documented evidence obtained by scientific apparatus, which is not a stopwatch.

The reality is that there are a lot of claims for higher power outputs then those in pre-Nationalisation and BR days obtained in preservation, including some by a couple of big red engines, but there is no real evidence scientifically obtained to support them. Train weight, stop watch figures and train resistance formulae just don't cut the mustard.

 

Duchess of Abercorn?

 

U1?

 

Yes, and even that is slightly spurious. Realistically, to measure a steam loco's power output, you do it with an indicator diagram. This wasn't done with 6234 but it was claimed entirely from data from the dynamometer car. This measures the drawbar pull (the tractive effort or force being delivered to the train after that needed to move the loco has been used and subtracted), integrates this Actual Traffic Effort with the speed at that time (Power = Force x Velocity or Torque x Angular Velocity [call it r.p.m.]) to produce the d.b.h.p. (Drawbar Horsepower), adds a (pretty accurate) calculated value to take into account that the train is going uphill so more of the horsepower is being used to move the loco against gravity to produce the e.d.b.h.p. (Equivalent Drawbar Horse Power). These values were 2511 hp and 2870hp respectively. They them added a conversion formula to obtain an approximation of the Indicated Horse Power (i.h.p.) being produced in the cylinders and this came out at 3348 hp (sometimes wrongly given as 3248 with 3333 at a different location). Some of this power is used to overcome the loco's resistance over the track and its own internal resistance, e.g. bearings and pistons moving within the cylinders. The record is claimed on the measured d.b.h.p. figure although the i.h.p. figure (higher than a Deltic or Class 86) commonly arises, but the d.b.h.p. figure is accurate and verifiable. Claims in preservation depend on speeds, train weights and resistance formulae, all imprecise but extrapolated to give a fictional i.h.p. figure.

I can accept that 6234's power output might have been exceeded in preservation, and probably has been, but putting a number to it is at best an educated guess.

 

No, but this engine explains why Tractive Effort, especially Nominal Tractive Effort from an Ian Allan ABC, cannot be used as a measure of power output. Let me present a fictional scenario.

The U1, with a Nominal Tractive Effort of 72940lb, has been on public display at Kings Cross. The driver preparing the A4 to work the Down 'Elizabethan' tells the running foreman the neither injector will work so he is failing the engine. The foreman says, "Don't worry, the U1's in steam. That's got twice the tractive effort of an A4. That will easily keep time!"

Just imagine the driver's comment.

 

A sight I would love to see (from Twitter):

 

@D1002 That's probably from a print issued by the P2 Trust - a painting by Chris Ludlow https://www.peintredurail.com/product/dream-team/

He's also done a painting of 3403 for the Trust.

If you like French trains, he has some wonderful paintings.

 

It is by Chris Ludlow. You can just about make out his signature in the lower left hand corner.

 

I have to confess that NatPres is littered with examples of "glass half empty" comments by negative nay-sayers who will never have a good word to say about ANY project, their contributions must be incredibly disheartening to many of those who literally dedicate their lives to some of these projects. Just sayin'.......

Foxy

 

Very well said Foxhunter!

 

But at what speed... ?

 

"Locomotive performance" thread just over there...

 

Locomotives of 6ft 2in wheel diameter or above are cleared for up to 75mph running.

Since the P2 has 6ft 2in wheels, it is likely that will be the accepted stipulated maximum.

 

Thanks Simon.
Rephrase the question -at what speed ? will the P2 be Britains most powerful steam loco...

 

I take it the beastie does feature electric headcode lamps, which I seem to recall being a condition of 75mph mainlining?

 

Probably got real time configurable Led Arrays that can tell you what its next stop is and remind you to take all your belongings with you...