Hornby P2

[Neil]

From the photo above the Thompson re-build, but leaving it as a 2-8-2 would look stunning.

[No Decorum]

1 hour ago, Neil said:

From the photo above the Thompson re-build, but leaving it as a 2-8-2 would look stunning.

The picture posted by bigwordsmith on screen 102 shows a Gresley 2-8-2. IMHO more stunning than anything Thompson or even Peppercorn might have produced. It’s the little touches, such as Gresley’s reverse curve in the running plate above the leading driving wheel rather than the step his successors used.

[JSpencer]

25 minutes ago, No Decorum said:

The picture posted by bigwordsmith on screen 102 shows a Gresley 2-8-2. IMHO more stunning than anything Thompson or even Peppercorn might have produced. It’s the little touches, such as Gresley’s reverse curve in the running plate above the leading driving wheel rather than the step his successors used.

 

The steps his succesors used was really an economy measure. Demanding less materials and man hours which were vitally important during the war.

That said after doing the excellently balanced B1, Thompson lost it on the bigger designs. In general, if a design is right it will also tend to look right too. And his big designs not only looked wrong but were equally bad performers too.

 

[Steamport Southport]

6 hours ago, atom3624 said:

The only place the Thomson one looks 'wrong', apart from dropping a pair of drivers, is the cylinders are too far back for visual 'balance' IMHO.

 

Otherwise, it's growing on me somehow!!

 

I still prefer 'the original'.

 

Al.

 

People always mention the cylinders being too far back. But probably the best looking Pacific had the cylinders there as well. As did the Kings.

 

 

 

Photo Ashley Dace Wiki common user.

 

 

Jason

[Paul_sterling]

2 minutes ago, Steamport Southport said:

 

People always mention the cylinders being too far back. But probably the best looking Pacific had the cylinders there as well. As did the Kings.

 

 

 

Photo Ashley Dace Wiki common user.

 

 

Jason

 

Lovely engines (the LMS Pacifics).

 

The key advantage they and the Kings had were the smaller cylinders, there was enough space to have the rear wheelset of the front bogie behind them, on the A2's, they bigger cylinders didn't permit that arrangement. that would have saved a fair distance for sure. 

 

Paul. 

[atom3624]

Lizzies and Duchesses are 2 favourites of mine as well.

 

Not as far back on the Lizzie, 'though better explained in the last post with the cylinder size, which just looks better.

 

I think Gresley got it right initially, then the kitchen had too many cooks in it.

 

Saying that, Peppercorn wasn't that wrong in design - I've 'Blue Peter' on display at the moment - another favourite of mine.

 

Al.

[melmerby]

Wasn't Thompson A2 a compromise using the original P2 rods for the cylinders? It meant moving the bogie forward and too much open space forward of the cylinders.

Peppercorn's tidying up made a huge improvement, visually, without compromising on performance. In fact one of the most successful of the UK pacifics

[JamieR4489]

32 minutes ago, melmerby said:

Wasn't Thompson A2 a compromise using the original P2 rods for the cylinders? It meant moving the bogie forward and too much open space forward of the cylinders.

I think the reason for the bogie being so far in front was because Thompson wanted the middle cylinder to drive the leading driving axle, whereas Gresley always drove off the middle (in the case of locos with six driving wheels) or the second axle (in the case of the P2s). This pushed the middle cylinder further forwards.

 

Jamie

[No Decorum]

2 hours ago, melmerby said:

Wasn't Thompson A2 a compromise using the original P2 rods for the cylinders? It meant moving the bogie forward and too much open space forward of the cylinders.

Peppercorn's tidying up made a huge improvement, visually, without compromising on performance. In fact one of the most successful of the UK pacifics

Thompson was also taken by the Western idea of having all connecting rods the same length. His subordinates were not particularly surprised that his Pacifics rode badly; after all, they didn’t look right. After he retired, Peppercorn’s tidying up was put in hand and to the surprise of all, the riding of Peppercorn’s locomotives was even worse. The problem was traced to inadequate side control of the bogie, which had originally been designed for the much smaller B17. Successive strengthening of the side springs solved the problem.

[DonnyRailMan]

What are the chances of Hornby making a Buggati nosed P2.

[Hilux5972]

3 minutes ago, DonnyRailMan said:

What are the chances of Hornby making a Buggati nosed P2.

The tooling of the chassis does look like it was designed with this option so we may see it in the future. I believe the body shell was also designed with the smokebox area as a seperate part to the rest of the Boiler. 

[manna]

G'Day Folks

 

The Buggati nosed P2's should have followed on from the original P2, within 12/18 months, which was logical..........But

 

manna

[melmerby]

.......But.

Hornby were short of cash

 

 

[atom3624]

But .... the original looked better!!

 

Sorry guys, I prefer the original iteration - good choice for PoW 2007.

 

Wonder what Peppercorn would have done with a 2-8-2 - bound to have looked pretty decent as well!!

 

Al.

[Paul_sterling]

1 hour ago, atom3624 said:

But .... the original looked better!!

 

Sorry guys, I prefer the original iteration - good choice for PoW 2007.

 

Wonder what Peppercorn would have done with a 2-8-2 - bound to have looked pretty decent as well!!

 

Al.

 

I reckon a different front end, squared off front running plate, smaller cylinders, higher boiler pressure, an A1 er-ised p2 basically. 

 

I reckon a railroad tornado and a railroad p2 could make a good coming together to make something like I imagine it would be. 

[atom3624]

Sounds about right - would have been a 'beast' certainly ...

 

Wonder what pressure PoW will be designed to operate at - order's just gone in to a German boilermaker this last week I think?

 

An increase would certainly mean 'Britain's most powerful XP steam locomotive' surely?  9P?

 

Al.

[rogerzilla]

 A Bugatti-nosed Sandringham would be cute.  But very, very niche.

Edited June 23, 2019 by rogerzilla

[Paul_sterling]

10 hours ago, atom3624 said:

Sounds about right - would have been a 'beast' certainly ...

 

Wonder what pressure PoW will be designed to operate at - order's just gone in to a German boilermaker this last week I think?

 

An increase would certainly mean 'Britain's most powerful XP steam locomotive' surely?  9P?

 

Al.

 

All three boilers will be identical, so whenever they are fitted to 60163, it'll be set to 250PSI, the P2 will depend whether they retain the original designs 21" cylinders, or use 19" ones copied from the A1. 

 

Paul. 

[atom3624]

Thanks and understood.

Would the higher pressure of the smaller diameter pistons / cylinders mean a higher tractive effort ... and any calculations on what that would be?

 

Thanks,

 

Al.

[melmerby]

1 hour ago, Paul_sterling said:

 

All three boilers will be identical, so whenever they are fitted to 60163, it'll be set to 250PSI, the P2 will depend whether they retain the original designs 21" cylinders, or use 19" ones copied from the A1. 

 

Paul. 

I'm sure I read somewhere the cylinders will be smaller than the original.

It's Here:

https://www.p2steam.com/design-study/

 

BTW reduce the wheels on a Coronation to 6' 2" and you would get slightly more TE than CotN in original form (43514 lbs against 43462 lbs)

[Paul_sterling]

15 hours ago, atom3624 said:

Thanks and understood.

Would the higher pressure of the smaller diameter pistons / cylinders mean a higher tractive effort ... and any calculations on what that would be?

 

Thanks,

 

Al.

 

If the 19" cylinders and 250psi are used, in conjunction with the P2's 6'2" wheels, the tractive effort will be identical to that of the Peppercorn A2, 40,430 lbs. 

 

Paul. 

[Paul_sterling]

15 hours ago, melmerby said:

I'm sure I read somewhere the cylinders will be smaller than the original.

It's Here:

https://www.p2steam.com/design-study/

 

BTW reduce the wheels on a Coronation to 6' 2" and you would get slightly more TE than CotN in original form (43514 lbs against 43462 lbs)

 

To some degree It still surprises me that the LMS went with bigger wheels for the Duchess (6'9") over the Princess (6'6"), on a route which needs more grip/grunt than it does speed carrying. The GWR went the other way with the Castle to Kings enlargement (6'8" then 6'6") and that did the Kings no harm, one of those reputedly touched 110mph (I think this is the un-streamlined speed record, for the UK at least) They clearly worked brilliantly as-built, but I'd have loved to see what a 6'2" version of the Duchess could do, I think that would have been seriously impressive.

 

Paul.  

Edited June 24, 2019 by Paul_sterling
Got my duchess digit wrong!

[atom3624]

I think the 6' 9" Duchess wheels were there allowing for the greater power the larger locomotive (boiler and steaming capacity) - cf Princess - would make and with a consideration for continual high-speed operation.

When you look at the 6' 2" wheels of some Standard and Bulleid Pacifics filmed at c.100 mph, they are spinning quite quickly!!

 

For a cross-reference, we've all heard of the occasional times 9F's, particularly Evening Star are supposed to have hit 90 mph with their 5' 0" drivers, and survived!!

 

My money's on more-than-adequate power and considerations for longevity.

 

Al.

[Paul_sterling]

18 minutes ago, atom3624 said:

I think the 6' 9" Duchess wheels were there allowing for the greater power the larger locomotive (boiler and steaming capacity) - cf Princess - would make and with a consideration for continual high-speed operation.

When you look at the 6' 2" wheels of some Standard and Bulleid Pacifics filmed at c.100 mph, they are spinning quite quickly!!

 

For a cross-reference, we've all heard of the occasional times 9F's, particularly Evening Star are supposed to have hit 90 mph with their 5' 0" drivers, and survived!!

 

My money's on more-than-adequate power and considerations for longevity.

 

Al.

 

I recall a note once, (it might well have been from O.S. Nock) , that as the britannias and the 9f shared identical motion, when you consider how fast the piston speed on the 9f was at 90, the britannias should have been able to match 4468! 

 

As a rule of thumb, a cast spoked "flywheel" is good to a maximum of 1000rpm, the 9F was doing around 8 revs per second, or 480rpm, it had a reasonable safety margin in respect of radial stress capacity (and had the extra benefit of a steel tyre encompassing the cast wheel, but this is disregarding hammerblow and other out if balance forces etc. 

 

The bullieds weren't spoked wheels, but I don't know about their overal centrifugal /centripetal strength, the tyres may well still have been the governing factor. 

 

Paul. 

Edited June 24, 2019 by Paul_sterling

[TheSignalEngineer]

7 minutes ago, Paul_sterling said:

 

I recall a note once, (it might well have been from O.S. Nock) , that as the britannias and the 9f shared identical motion, when you consider how fast the piston speed on the 9f was at 90, the britannias should have been able to match 4468! 

Using speed and wheel circumference I would estimate that 90mph on a 9F would be equivalent to approximately 120mph on an A4 at the same rpm.