V4 2-6-2 No. 3403

Do please tell us more about 3402's boiler. I had understood that both locos kept their original boilers until they were due for replacement, at which point they were withdrawn for scrap. Did the 1945 replacement boiler still include a thermic syphon (which dictated the need for a steel box) or was it just a plain steel box or was it given a copper box. Sorry for the questions, but I'm curious and too lazy to research it myself.

Peter

 

Are their any similarities in the bust casting on Green Arrow, and the one for the proposed V4????

 

With monel stays, all welded steel constriction and some FEA stress work, the thermic siphons could reach their on-paper potential and become trouble free.

The bottom line is that although the designers knew the thermodynamic principle behind them was sound, they did not know the point by point temperature gradients in the material and firebox, and the resultant stresses and strains at every point in the box. This means the inter-relationships on stays, material, temperature and pressure at every point in the boiler remain to this day largely unknown.

You can compute these generally, which was done, but meshing it with billions of elements delivers far greater insight than hand calcs ever can.

We can now comfortably model that as an FEA study from the CAD models required to manufacture the boiler.

The real question becomes how much design change does the organisation have appetite for? Or cash. FEA studies have a habit of starting at 5 figures and moving upwards.

However, engaging with a university with a corporate sponsor as oversight would be a good option. Same idea as the crank axle. It would make an excellent thesis project.

For further reading.
https://www.national-preservation.com/threads/boiler-design-construction-ex-patriot-thread.641883/

 

Other options for the draughting could be a Lempor or Jos Koopmans 4-nozzle design (other options are also possible).

 

I'm looking forward to seeing this when it's done, but am I the only one who thinks it would be nice not to name it?

 

Given the A1 and P2 designs, I'd be surprised if it wasn't another Kylchap. Out of interest (and I ought to know this) has there been a Lempor installation on a 3 cylinder machine?

 

"guycarr360, post: 2244771, member: 224"]Are their any similarities in the bust casting on Green Arrow, and the one for the proposed V4????"[/QUOTE]

Sort of, the Monobloc casting found on the original P2 and V2 were also a feature of the V4. But since the new P2 isnt having a Monobloc casting, its not likely that the new V4 will either ?

As for thermic syphons a dont think that many we're removed from Bulleid Pacifics, dont know that any have in preservation. Bulleid probably knew a bit more about welding/ steel fireboxes than his LNER counterpart ? . They are an interesting feature and their contribution to boiler life and as an occasional safety feature isn't perhaps fully appreciated.

As for the draughting the no of locomotives that ' steam perfectly well with a standard chimney' that were found to be worth another coach or even power class after going ' double/ multiple orifice' steam is legion. the A3/V2 being a prime example.

 

Perhaps if the New Patriot fails to perform we might find out...

 

According to David Wardale's book "Red Devil," Porta fitted some 3 cylinder tank locomotives in Argentina with Lempors, among other modifications. Apart from mentioning an increase in power, Wardale didn't go into much detail about how they performed.

 

The picture of the blastpipe recently posted on the Patriot thread doesn't fill me with confidence regarding the efficiency of the device. Not intended as a criticism of the people building the locomotive.

 

A valid point, if you believe the description of operation of the de Laval nozzles given on page 92 of "Red Devil", they will be very sensitive to the pulsating nature of the exhaust, so it might be an interesting learning exercise to get one working on a three cylinder engine.

 

About time I read it again - if only the print were larger!

 

Sort of, the Monobloc casting found on the original P2 and V2 were also a feature of the V4. But since the new P2 isnt having a Monobloc casting, its not likely that the new V4 will either ?

[/QUOTE]

Thanks for the reply, so lessons learned from the V4 could be used towards the V2, would love to see Green Arrow join the stable at Whessoe Road, looked after by A1ST.

Pipe dream, now going out to put EuroMillions on!!!!

 

The monobloc casting currently fitted to the V2 could be displayed on a plinth at the NRM so that people could see what one looks like. This would then enable the rest of the loco to be restored using separate cylinder castings.

Bob.

 

The cost monoblock vs a fabricated block is to me a no brainer.

I think this has been discussed a few times on here, and its a good idea. The doubt is that the NRM want to manage 2 big mainline locos at once given the last overhaul of a big green LNER machine...

 

On the thermic syphon question, only one Bulleid boiler had them removed, which ran on 35014 and 35022 at least in that condition. I think the results could best be described as inconclusive; superheat temperatures were apparently higher but it was more difficult to get good steaming, even after brick arch modifications. The early NBL-built fireboxes did have problems with cracking and stay failures around the syphon-throatplate connection; they were resolved with monel stays in that region and, reading between the lines, redesign of the connection to make it less stiff. I suspect this is a classic case of 3402 being a single example, so it was easier to remove the problem rather than solve it.

 

I had the same thought. The passages do look rather twisty.

 

AFAIK the Patriot is being built as a true replica.

 

It's the NRM. It'll be converted into a centrepiece in another coffee shop.

 

The thing is, if I recall correctly the monobloc casting was what earned Green Arrow its preservation. Remove that and it's just another 2-6-2. Much as I would like to see it in action again, its time in the sun has ended and that should be accepted.