'Up-sizing' the RHDR engines

[NZRedBaron]

This is an odd question, I realise, but I've been wondering this for years now:

If you scaled up the locomotives of the Romney, Hythe and Dymchurch Railway from 15in to standard gauge, what would their dimensions be? Would they fit in the standard British loading gauge?

[Nearholmer]

Assuming that your handle implies that you are a New Zealander, they suit you, because they are proportioned like Cape Gauge locos more than standard gauge, and if you did pump them up to standard gauge, not only would they be very big, the cabs etc would be disproportionately big.

[Edge]

You’d have to upsize them differently for different bits of the engine. The gauge is about a quarter of the size of standard, but the locos superstructure is about a third the size of their prototype inspirations. (Greenly did this deliberately and it apparently has been the saving of the locos from an engineering perspective)

 

no reason that they wouldn’t fit in the loading gauge if they were built as full size engines (as above, tenders and cabs would be a bit too big for British standard) - but as with most express locomotives, I doubt that they would have had freedom to roam everywhere over the network in a hypothetical scenario where they were built full size :) 

Edited November 15, 2023 by Edge

[Nearholmer]

I’m pretty certain that this is a “correctly” proportioned 15” gauge model of a standard gauge loco, and you can see how tiny and delicate it looks compared with the practical and chunky Greenly designs:

 

[rodent279]

I was wondering 

 

2 hours ago, NZRedBaron said:

This is an odd question, I realise, but I've been wondering this for years now:

If you scaled up the locomotives of the Romney, Hythe and Dymchurch Railway from 15in to standard gauge, what would their dimensions be? Would they fit in the standard British loading gauge?

 

I was wondering exactly the same question when looking at this photo on Flickr, courtesy of MKDarlo. It would be a rather impressive machine as a standard gauge 4-8-2.

 

 

[Nearholmer]

The issue might become more obvious in this view.

 

[rodent279]

Looks like if they were embiggened to standard gauge, they'd struggle to fit the most generous of the various UIC loading gauges.

[Compound2632]

3 hours ago, Edge said:

You’d have to upsize them differently for different bits of the engine. The gauge is about a quarter of the size of standard, but the locos superstructure is about a third the size of their prototype inspirations. (Greenly did this deliberately and it apparently has been the saving of the locos from an engineering perspective)

 

Wasn't Greenly responsible for 00 too?

[john new]

For at least one then the answer is obvious. Green Goddess = Flying Scotsman. In scaling up the necessary engineering compromises for practicality would have to be made in reverse. 

[Nearholmer]

Somewhere, I’ve got a slide photo that I took of Green Goddess next to a scale model Flying Scotsman that visited the RHDR donkeys years back (the latter is currently for sale in dismantled condition if you fancy s project) and the difference is immense. I’ll see if I can find it.

[C126]

You might be interested in J. B. Snell's One man's railway, which I am reading at the moment :

 

https://www.abebooks.co.uk/9780946537808/Mans-Railway-Snell-John-0946537801/plp

 

[russ p]

What about the Canadian outline locos are they bigger still?

[Wickham Green too]

4 hours ago, Nearholmer said:

... not only would they be very big, the cabs etc would be disproportionately big.

... as would the drivers !

[Jeremy Cumberland]

The first RHDR locos were essentially 1/3 scale A1s running on 15-inch gauge track, although as others have said, other compromises were also made, as they are for our own rather smaller "scale" models.

 

If the only thing you are considering is track gauge, then if you scaled everything up equally so that the RHDR locos would fit on standard gauge, then they'd be about 25% oversize. However, not only would they not fit through platforms, bridges and tunnels, and would clout many lineside structures, they also wouldn't run through any pointwork. As with (most of) our models, the wheel flanges are overscale and the back to back is proportionally too narrow. The RHDR back to back is, as far as I am aware, 13⅝", which scales up to 1308 mm. The check rail to check rail distance on Network Rail is, I think, 1347 mm (and the standard back to back is 1360 mm).

Edited November 15, 2023 by Jeremy Cumberland

[rodent279]

Looking at the question differently, assuming the loco was scaled up to standard gauge, so that say the buffers were at normal standard gauge separation and height, what would the track gauge be?

I'm guessing Cape gauge or metre gauge would be about right.

[Compound2632]

11 hours ago, Jeremy Cumberland said:

As with (most of) our models, the wheel flanges are overscale and the back to back is proportionally too narrow. The RHDR back to back is, as far as I am aware, 13⅝", which scales up to 1308 mm. The check rail to check rail distance on Network Rail is, I think, 1347 mm (and the standard back to back is 1360 mm).

 

OK, so if the RHDR locos were to be rebuilt to an equivalent of P4 standards, the track would have to be relaid to 18.83 inch gauge!

[NZRedBaron]

Fair enough.

 

But then in that case, let's say the numbers get fudged enough to fit within, let's say, the LNER composite gauge as a baseline. What might the various engines size out as?

[John Besley]

22 hours ago, Nearholmer said:

The issue might become more obvious in this view.

 

 

I am currently building a 7/8ths 0-8-0 as a 10-i/4" gauge railway on 16.5mm track and that picture showing how much she is leaning to one side is rather intresting

 

Bit like an elephant riding a bicycle...

[kevinlms]

59 minutes ago, John Besley said:

 

I am currently building a 7/8ths 0-8-0 as a 10-i/4" gauge railway on 16.5mm track and that picture showing how much she is leaning to one side is rather intresting

 

Bit like an elephant riding a bicycle...

Anything is possible!

[Jeremy Cumberland]

4 hours ago, NZRedBaron said:

Fair enough.

 

But then in that case, let's say the numbers get fudged enough to fit within, let's say, the LNER composite gauge as a baseline. What might the various engines size out as?

I'm not really sure what you are asking. Green Goddess, Northern Chief and Southern Maid were built as 1/3 scale models of an LNER A1 class, and were about as accurate as any other scale models of the time. If you scaled one back up, it would be the size of Flying Scotsman, the same as if you scaled up a 4 mm/ft Hornby Flying Scotsman.

 

However, if you use track gauge as the scale factor, then the RHDR locomotives would come out about 25% longer, taller and wider than Flying Scotsman. But using the same criterion, the Hornby model would come out 14% longer, taller and wider than the prototype.

[NZRedBaron]

It's because I've got a battered hardback copy of Brian Haresnape's "Gresley Locomotives", and in it is mentioned on page 20 and 21 of a proposed 4-8-2 concept for heavy express passenger trains; ever since I read that, I've had this notion of using the RHDR's Sampson and Hercules as visual reference for this proposed design.

[Hal Nail]

9 minutes ago, NZRedBaron said:

a proposed 4-8-2 concept for heavy express passenger trains

 

[Jeremy Cumberland]

1 hour ago, NZRedBaron said:

It's because I've got a battered hardback copy of Brian Haresnape's "Gresley Locomotives", and in it is mentioned on page 20 and 21 of a proposed 4-8-2 concept for heavy express passenger trains; ever since I read that, I've had this notion of using the RHDR's Sampson and Hercules as visual reference for this proposed design.

Samson and Hercules have notably smaller wheels than the A1 miniatures (1' 7½" instead of 2' 1½"). If you scale these up, then Green Goddess, Northern Chief and Southern Maid have the equivalent of 6' 4½" drivers (LNER Class A1 drivers were 6' 8"), whereas Samson and Hercules have 4' 10½" drivers, which is rather small for an express passenger locomotive, even if you factor in 15-inch gauge wheels being a little undersized because of the proportionally deeper flanges.

Edited November 16, 2023 by Jeremy Cumberland

[Cruachan]

3 hours ago, John Besley said:

 

I am currently building a 7/8ths 0-8-0 as a 10-i/4" gauge railway on 16.5mm track and that picture showing how much she is leaning to one side is rather intresting

 

Bit like an elephant riding a bicycle...

The image is leaning to one side rather than the loco - Otherwise The End of The Line restaurant building on the right would be demonstrating a significant degree of subsidence.

[John Besley]

29 minutes ago, Cruachan said:

The image is leaning to one side rather than the loco - Otherwise The End of The Line restaurant building on the right would be demonstrating a significant degree of subsidence.

 

Ok hadn't spotted that point