Imaginary Locomotives

[cctransuk]

5 hours ago, John Besley said:

8https://www.ebay.co.uk/itm/Vintage-Die-Cast-Kit-Built-BR-Brightlingsea-4-6-0-Locomotive-Tender-340-/303972613635?_trksid=p2349624.m46890.l49286

 

 

 

Definitely the little-known Bulleid GT2.5 .

 

John Isherwood.

[JimC]

2 hours ago, BernardTPM said:

 Outside third rail pick-up is unusual, though I suppose kind of appropriate for Southern...

I recall a schoolmate's father had a very large (treble garage sized) 00 layout which was outside rail pickup, so it existed. Certainly looked a lot better than Hornby 3 rail track!

[Flying Pig]

9 hours ago, Johnson044 said:

...and it somehow convinces.

 

It's actually much more convincing than the Leader (or GT3 for that matter).  Really quite surprising that Bulleid didn't have a go at gas turbine power.  What about a gasified turf version for CIE?

[Zomboid]

If it had the BFB wheels I'd be totally sold

[John Besley]

14 hours ago, Zomboid said:

If it had the BFB wheels I'd be totally sold

I definitely want to build a static one... need a Dapol BofB and a scrap class 25 body shell

[Dr Gerbil-Fritters]

Couldn't a gas turbine also be built as a cab-forward? 

 

Nothing to shovel in the back end, surely.

[BernardTPM]

Two cabs?

[John Besley]

2 hours ago, Dr Gerbil-Fritters said:

Couldn't a gas turbine also be built as a cab-forward? 

 

Nothing to shovel in the back end, surely.

True but you can just see OVSB thinking along the lines of a development project and Eastleigh withdrawing a WC or BofB for this much the same as he tested the Lemipre exhaust and sleeve valves on an Atlantic first before building the Leader 

[DenysW]

This mostly is a question repeated from several comments on this thread about the Gresley P2 2-8-2 Edinburgh-Aberdeen express design that didn't seem to me really to receive answers at the time of asking. Why didn't Gresley go for a 4-6-2+0-4-4 reverse-Mallet/Engerth/Garratt hybrid. (Or a 4-4-2+0-4-4 if proper engineering calcs would have shown it wouldn't suffer from wheelspin). Due to my limited IT skills the attached picture is a cut/paste from a Hornby picture of one of their models, but it appears to show that the total length wouldn't need a drastic extension if you got rid of the classic-Garratt front water tender. I realise this does not address the bigger boiler to get to the P2 design starting tractive effort, or the loss of tender volume to the wheels and drives. Is there something simple I'm missing that would rule it out? It would (probably) not infringe on the Beyer, Peacock intellectual property as that was based around the use of a Bissel truck at the smokestack end and  consequent use of the water tender as a counter-weight.

[Compound2632]

1 hour ago, DenysW said:

Is there something simple I'm missing that would rule it out?

 

Yes. Simplicity.

[PenrithBeacon]

1 hour ago, DenysW said:

...

Why didn't Gresley go for a 4-6-2+0-4-4 reverse-Mallet/Engerth/Garratt hybrid.

...

Perhaps because the boiler wouldn't be able to support the additional cylinders amongst other things

[John Besley]

The advantage of a Garrett is with a drop frame a very large boiler can de fitted to supply in effect 2 x 4-6-2 with one crew instead of a second crew

[Satan's Goldfish]

And the more coal and water that's used, the less weight would be on the driving wheels under the tender which wouldn't help with getting power to the rails.

[The Johnster]

It might work if the cylinder sizes were reduced, which would of course negate some if not all of the T.E. gain from the extra driving wheels, otherwise you would need a boiler of twice the steam raising capacity to feed twice the number of cylinders for a sustained high output, which is a fundamental requirment of an express passenger loco, especially on the ECML.  The water capacity would be severely compromised and more coal capacity needed, resulting in a bigger, heavier tender, again reducing the advantages gained from the extra driving wheels. and the firebox would need to be bigger as well, possibly to the extent of needing mechanical stoking or oil firing.

[Compound2632]

4 hours ago, DenysW said:

Is there something simple I'm missing that would rule it out?

 

Also the Locomotive Committee of the Board. On the cash-strapped LNER even they would see through such a hobby. At least the P2 looked reasonably like the cost-effective machines that had gone before. No wonder Bulleid's experimental locomotives had to wait until he'd moved elsewhere.

[PhilJ W]

Not forgetting that the A4's were light locomotives built for speed with trains built as light as possible. 

[Gibbo675]

28 minutes ago, PhilJ W said:

Not forgetting that the A4's were light locomotives built for speed with trains built as light as possible. 

You wouldn't want one to land on the end of your................................................................finger !!!

[Compound2632]

41 minutes ago, PhilJ W said:

Not forgetting that the A4's were light locomotives built for speed with trains built as light as possible. 

 

Weights (loco only)

A4: 102 t 19 c

A3: 96 t 5 c

A1 (Gresley): 92 t 9 c

A1 (Peppercorn): 104 t 2 c

A2 (Peppercorn): 101 t 0 c

A2 (Thompson): 101 t 10 c

A2 (Raven): 101 t 10 c

P2: 107 t 3 c

Coronation (streamlined): 108 t 2 c

Coronation (unstreamlined): 105 t 5 c

Princess Royal: 104 t 10 c

Rebuilt Royal Scot: 84 t 18 c

King: 89 t 0 c

Merchant Navy: 94 t 15 c

West Country: 86 t 0 c

 

So only the LMS pacifics, P2s, and Peppercorn's A1s were heavier. The original Gresley pacifics were the lightweights, certainly compared to their contemporaries, the Raven pacifics!

[Gibbo675]

8 minutes ago, Compound2632 said:

 

Weights (loco only)

A4: 102 t 19 c

A3: 96 t 5 c

 

Coronation (streamlined): 108 t 2 c

Coronation (unstreamlined): 105 t 5 c

 

 

So only the LMS pacifics, P2s, and Peppercorn's A1s were heavier. The original Gresley pacifics were the lightweights, certainly compared to their contemporaries, the Raven pacifics!

Hi Stephen,

 

The LMS pacifics were not bad considering that they were several feet longer along with an extra cylinder and associated wobbly bits.

 

Gibbo.

[rodent279]

1 hour ago, Compound2632 said:

 

Weights (loco only)

A4: 102 t 19 c

A3: 96 t 5 c

A1 (Gresley): 92 t 9 c

A1 (Peppercorn): 104 t 2 c

A2 (Peppercorn): 101 t 0 c

A2 (Thompson): 101 t 10 c

A2 (Raven): 101 t 10 c

P2: 107 t 3 c

Coronation (streamlined): 108 t 2 c

Coronation (unstreamlined): 105 t 5 c

Princess Royal: 104 t 10 c

Rebuilt Royal Scot: 84 t 18 c

King: 89 t 0 c

Merchant Navy: 94 t 15 c

West Country: 86 t 0 c

 

So only the LMS pacifics, P2s, and Peppercorn's A1s were heavier. The original Gresley pacifics were the lightweights, certainly compared to their contemporaries, the Raven pacifics!

Goes to show how light even the Merchant Navies were, considering their size and, after rebuilding, capability. I guess that's to do with the welded boiler and firebox, and BFB wheels?

 

Edit: the P2 is lighter than it looks.

Edited May 15, 2021 by rodent279

[DenysW]

All comments accepted as valid. You'd also need proper articulation to transfer enough of the weight to the rear driving wheels.

 

I was merely musing about what other compromises were available other than going for a 2-8-2 mogul  (up from a 4-6-2 pacific) when the spec calls for a 25% increase in starting tractive effort compared to LNER pacifics.  The 4-4-2 + 0-4-4 version keeps you at 8 driven wheels, with the shorter driven wheelbase, but gives you the articulation and 6, smaller, cylinders. So a different compromise. I suspect the locomotive committee, despite passing all of the detail variants on the mogul they let through, would have choked on the lack of reference designs for express articulated locos.

[PhilJ W]

1 hour ago, DenysW said:

All comments accepted as valid. You'd also need proper articulation to transfer enough of the weight to the rear driving wheels.

 

I was merely musing about what other compromises were available other than going for a 2-8-2 mogul  (up from a 4-6-2 pacific) when the spec calls for a 25% increase in starting tractive effort compared to LNER pacifics.  The 4-4-2 + 0-4-4 version keeps you at 8 driven wheels, with the shorter driven wheelbase, but gives you the articulation and 6, smaller, cylinders. So a different compromise. I suspect the locomotive committee, despite passing all of the detail variants on the mogul they let through, would have choked on the lack of reference designs for express articulated locos.

The LNER did try out boosters.

 

[PhilJ W]

More boosters.

[DenysW]

A quick look on www.lner.info ( a )  completely agrees with these posts on boosters , ( b ) reports them as ineffective above 30 mph, and ( c ) in need of drivers experienced in the use of boosters to get the low speed benefits . Underwhelming presumably down to small wheel size? Also tried , with the mixed results, shortly before the the Edinburgh-Aberdeen design was started, so the conclusions would have been available to the team that ended up going for a mogul.

 

My alternate reality was to split the 8 driving wheels, permanently engaged, using articulation.  The booster experiences could have been used either to "prove" or to "disprove" the articulated concept, depending on preconceptions.

[DK123GWR]

4 hours ago, DenysW said:

reports them as ineffective above 30 mph

Would this be a problem of itself though, if the stated aim (for the Aberdeen locomotives at least) was to improve starting tractive effort?