Great British Locomotives Magazine

[Pebbles]

As there have been comments regarding the shape of A1/A3 etc boilers I decided to examine some of the earlier Hornby models. In the prototype the front of these boilers is about 5ft 9ins diameter whilst at the widest point of the tapered section they are 6ft 5ins diameter, a difference of 8inches. In 4mm scale this come to 2.67mm. As the tapered section is a true cone this must mean that the height difference is about 1.34mm.
Having established a common datum and using a height gauge, and taking a number of sample readings, the difference in the respective heights on a Hornby tender drive A3 comes to about 1.4mm.
I appreciate that the smokebox is 6ft diameter but over the cladding the front of the boiler is also about 6ft and if, as is most likely, the cladding - other than behind the rear drivers - is of a similar thickness then the relative variation must hold true.
The tender drive A1 and indeed the older version of the Rail Road A1 have height differences closer to the Roche drawing. As many will be aware Roche, and others, didn't appreciate that whilst the GWR boilers are a frustum of a cone the tapered sections of LNER boilers are a true cone.

[greenglade]

As the tapered section is a true cone this must mean that the height difference is about 1.34mm.
Having established a common datum and using a height gauge, and taking a number of sample readings, the difference in the respective heights on a Hornby tender drive A3 comes to about 1.4mm.

As many will be aware Roche, and others, didn't appreciate that whilst the GWR boilers are a frustum of a cone the tapered sections of LNER boilers are a true cone.

hi Pebbles... I haven't read the rest of this thread so not clued up on what exactly is being discussed here but did pick up on your comment regarding the taper on Gresley's boiler for the A1/A3... I'm afraid if you are saying that it's an equal cone which is what I see as a true cone then I will have to disagree with you, it's not a true cone, the top angle is far greater than the lower.. I don't have the drawings in front of me to give figures but being in the process of planning a build for a 5" gauge boiler of a Gresley A1 I'm very familiar with the boiler profile. The same goes for a smaller 3 1/2 gauge pacific I have that is completed and in steam.

regards

Pete

[Atlantic 3279]

Memory suggests a maximum clad diameter of 6' 10" or thereabouts over the widest part of the cone, shown on a GA or pipe drawing of the P1, reproduced to a rather small scale on the cover of one of the Yeadon series. Compared to the almost dead-on 6' diameter of the smokebox and matching cladding of the forward portion of the boiler, this suggests a top height differential in 4mm scale nearer 1.6mm than say 1.3mm, for a true-cone arrangement. That is consistent with the greater inclination of the top of the cone that I found necessary when critically comparing a tender-drive A3 body moulding with the Isinglass V2 drawing. It was failure to correct this discrepancy that had (in part) made it impossible for me to put my V2 conversion together properly at the first attempt.

[Pebbles]

On Page 26 of O.S.Nock "The Gresley Pacifics " combined parts 1&2 there is a dimensioned drawing of the boiler, you may need a magnifying glass! On pages 30 ,31 and 32 there are other helpful drawings. That on page 31 shows the lagging above the trailing driving wheels. This drawing is as far as I can make out to 12mm to the foot and using this scale the height difference comes to 1.366mm. I will leave to others to decide from these drawing whether or not the tapered section of the boiler is part of a true cone. John drew Isinglass drawing to 4mm to the foot they were not reduced to that size however, taking a line parallel with the top of the front of the boiler and lining it up with the highest point my digital caliper gives me 1.4mm.

[Saint Johnstoun]

I'm moving the Garter Blue discussion to a new Topic!

[Saint Johnstoun]

FS Tender proving useful. Here is one fitted to a Hornby underframe and cut down at the rear a la 1948 exchanges.

[2002EarlMarischal]

Can't go wrong with that Allan!

[greenglade]

I saw my first model from this collection in Sainsbury's a couple of weeks ago, today I saw FS... looked pretty good. Shame I don't collect 00 gauge any more.. Mind you I still haven't been able to sell off my untouched collection that's been mounted in a cabinet on the wall for the last 20 years, most of which are limited edition's, never run. Perhaps when I've built more 0 gauge models to fill the void they will be easier to part with... yeh right...lol

I have subscribed to the 'Build an 0 gauge A4' magazine so I'm moving in the right direction..

Pete

[Mercator II]

Looking mighty fine again, any chance of a few more pics of the cut down from other angles please Allan?

Is that one destine for an A4 or 3?

I am hoping the last parts for my chassis will arrive today, then work can commence on one of my A4s, time to research green A4 names and tender combinations

oOo

Brian

[Saint Johnstoun]

The cut down tender is for A4 Seagull which will be in garter blue but with BR number and BRITISH RAILWAYS on the tender.

[Saint Johnstoun]

I'm throwing open this challenge! Two drawings of the proposed Streamlined Peppercorn A1 class - does anybody reckon they could create them using GBLC A4 bodies? The firebox is bigger and the front end is longer so.....

[D2100]

I'm fascinated by these proposed locos. What on earth was the rationale for applying a Gresley idea to a modern design in an era of austerity?

[Darryl Tooley]

Smoke-lifting perhaps?

[S.A.C. Martin]

Interesting to note that had Edward Thompson had his way in the 1940s, 4470 Great Northern would also have been streamlined when rebuilt.

Peppercorn revived the proposals for the classes A1 and A2 but nothing came of them. Wooden mock ups of the A2 suggest the high running plate and access to the cylinders and driving wheels would have been maintained, without the A4 style valances, and that only the central bit of the "wedge" at the front end would have been applied.

[Pebbles]

If its any help page 176 of "East Coast Pacifics at work" by Peter Townend and page 98 of "British Steam Horses" by George Dow may give additional detail.