A1SLT... What next.

The P2 has long been a favourite at the annual Covenantors meetings, but as I've not made the last two, due to holidays, I'm not aware of the ground swell of opinion for Lot 3, but I'm all for a V4.!

As for draughting, I can't find a reference to the V4 design, but I assume it followed V2 practise, with a plain single blastpipe, though 5 V2's did get double Kylchap's towards the end of their lives. I would be surprised if any new V4 built by the A1 Trust didn't have a single Kylchap though.

 

Might even get a Lempor. Which represents a worthwhile improvement over the Kylchap.

 

But you and I aren't the designers

 

Or perhaps a Kylpor...?

 

Or even better still, a Lemprex......

Cheers

Alan

 

Are advanced exhaust systems such as Lempor (and Kylchap for that matter) compatible with a 3 cylinder, single chimney locomotive. I only ask because I can only recall seeing examples of their use in double chimney applications.

 

Yes. Although it has to be worked out for the particular locomotive.

Given the performance of Bantam Cock when it was tested on the GE fitting it with an advanced exhaust would probably put it in Royal Scot territory!

 

I believe the choices mentioned in HR were the result of what might be called 'blue sky thinking' by the Trust to establish a choice of locomotive to follow No. 2007. It would be sensible to keep the design and engineering teams gainfully employed once the P2 is finished and a smaller type for use on preserved lines or the West Highland route would give the Trust a 'foot in both camps' as it were. My vote goes to the V4, a tender engine with a decent range, wide firebox for variable coal and a very good tractive effort/weight ratio. I believe the Trust first mooted the P2 as long ago as 1994....

Foxy

 

One feature of these systems is a comparatively large blast nozzle area ' divided into multiple streams to give more 'entrainment' with less pack pressure
this makes for, not withstanding the accepted narrower degree of diffuser(chimney), a wide chimney orifice . Its also long been accepted that a very definite minimum length of chimney is required, so for a locomotive with a 4 inch dia blast pipe area and a roughly 4ft height to the chimney lip increasing the effective diameter to 5 inch dia and spacing out the nozzles will need an extra 5-6 inches of 'chimney' height and an increase in width. which the loading gauge and /or British aesthetic sensibilities may not accomodate - the blast nozzles on the Le maitre for instance are almost at the floor of the smokebox and the chimney is notably ' wide' The solution is to subdivide the blast area into two arrays which are narrower so that the correct proportions can be accomodated ( so Tuplin had an idea of what was going on) in the Height available. There are plenty of narrow gauge engines with single lempors...
As for 3 cylinders i cant think of an example but Lemaitre and Kylchap work fine so i cant see there being a problem.

 

Thanks for the replies. Does that mean that, although feasible, the performance gains and other benefits would be limited due to the relatively narrow chimney? Any significant increase in the width would obviously change the external appearance of the loco, which I am sure the A1SLT would want to avoid.

 

Yep... although the chimney looks to be quite tall with a bit of flare so you could probably get a way with a little extra width, which would offer some improvement with little extra cost. The Clover leaf splitter on a Kylchap or Kylpor arrangement -whilst perhaps not the ideal- is more compact than lempor nozzlesand might be worthwhile for a one off build, but perhaps not worth scrapping and replacing on an existing loco without a specific need for better performance.

 

The world has changed in many ways since steam locomotives were being built in numbers, none more so than in computer modelling. The A1 trust has embraced this in terms of getting the design right (CAD) and in vehicle dynamics (VAMPIRE).

There is, however, another field that could possibly be exploited, and that is computational fluid dynamics (CFD). This is used extensively by Formula One teams to get their designs basically right before taking to the wind tunnel and ultimately the race track. One team even tried to skip the wind tunnel stage, although this was not an unqualified success.

If I were in a position to commission a new locomotive I would seriously consider using this technique to optimise the choice of exhaust and its configuration, and maybe other aspects of the design, before cutting any metal. Ultimately you may not extract the last few percent of performance without testing and tweaking, but would you really need to?

Just a thought.

Dave

PS no idea how much this would cost or if the trust already do something similar.

 

CFD is a nice idea but I think you will find that the costs are very high (to put it mildly). For what one F1 team spends on CFD you could probably build a fleet of 20 of the chosen design. I accept that the models will be simpler and require less hours crunching the numbers but if done on a paid basis you could easily rack up a huge bill. Now what you need is a retired F1 designer looking to donate their time for free to a worthy project, now somewhere I have a certain Mr. Brawn's telephone number.....

 

The Bloodhound SSC team are using CFD and certainly aren't spending F1 levels of money on it! Conceivably, it is the sort of thing you could get done cheaper if you could enthuse a University engineering department to take it on as a little project, maybe an undergraduate research exercise?

Tom

 

I beleive that this has been looked at but the complications of a variably pulsed flow over a range of pressures defies an exact configuration,
Result = an approximation, which is precisely what we already have with 150 years of experience and experiment behind it.

A total restart approach to draughting may result in something that doesnt look like a chimney.... no one wants a steam loco without a chimney do they ?

 

What should A1SLT do next? Keep getting good PR from unexpected people:

James May - on Twitter:
"I've been asked to make another part for the P2 locomotive project. It's the, um, cock flange. (Part of the slacking pipe). "

"Forgot to include the evidence. Here it is.
https://twitter.com/MrJamesMay/status/469017321760358401/photo/1"

Richard

 

Drawn in 2007 and named for the a1st...
It would be good if the one it's being named after made a few comments about it.. That might bring a few investors.

 

Given his recent comments about Putin, probably best if he keeps quiet.........

 

"indeed Its a jolly good thing thats its painted that lovely green, not black and red like those db types or one might be thinking we were about to annex Belgium dont you know"

 

Oi, nowt wrong with the livery of DB steam locos.