Imaginary Locomotives

[34theletterbetweenB&D]

Or appropriately geared pairs of single cabbed Deltics either end, of BoBo configuration (they didn't need to be Coco at 99T, and reducing the bogies to Bo and losing a cab makes them lighter yet)? There's 6,000 hp which should be good for 140mph on a circa 500 ton all up set, so 8 mk1 coaches as the filling (for a truly exciting ride) and three out of four engines likely to be available at worst...  yeeeeha!

[scots region]

If Kestrel had not come in overweight probably more likely that we would have seen loco hauled push-pull sets for 125mph operation with Kestrels on one end and driving trailers on the other.

Now that won’t break the bank, and is operational interesting.

[Suzie]

Or appropriately geared pairs of single cabbed Deltics either end, of BoBo configuration (they didn't need to be Coco at 99T, and reducing the bogies to Bo and losing a cab makes them lighter yet)? There's 6,000 hp which should be good for 140mph on a circa 500 ton all up set, so 8 mk1 coaches as the filling (for a truly exciting ride) and three out of four engines likely to be available at worst...  yeeeeha!

 

Here is a class 54 Deltic 'A' unit for use on 1960's 140mph trains. Would there be one at each end or would there be a 'B' unit instead for the second loco? Would high speed trains at this time only need 4x Mk1s (perhaps just 1st class Pullmans) and use a driving trailer rather than a full length train? Performance should be similar to 91 hauled trains when a pair of Deltics is used.

 

 

Bo-Bo wheel arrangement should help with high speed, and perhaps the Mk1 trailer rakes would be articulated 4-car sets too...

[DavidB-AU]

I give you the HS120 'Wagtail' 125mph high speed DMU 4-car demonstrator. Twin power cars with 2000HP each. Traction motors are one per bogie on power cars and adjacent trailer cars to spread the weight (and to save me having to find more appropriate bogies!) just like the Blue Pullman. Should make a nice 8-car set in normal operation.

Imagine an electro-diesel version for through running to Weymouth with a 4TC before slidey rail was extended beyond Bournemouth. No need for a bagpipe 33!

 

Cheers

David

[Satan's Goldfish]

'Class 54' + 4tc would work. 2 of them back to back would make a 'hst'.

[Suzie]

It would be the 'Bentley' of HSTs - adequate power plus 50%. I guess what we need now is an 8-TC with Pullman windows and livery as well as bogies that are good for 140mph.

[The Johnster]

Here is a class 54 Deltic 'A' unit for use on 1960's 140mph trains. Would there be one at each end or would there be a 'B' unit instead for the second loco? Would high speed trains at this time only need 4x Mk1s (perhaps just 1st class Pullmans) and use a driving trailer rather than a full length train? Performance should be similar to 91 hauled trains when a pair of Deltics is used.

 

Deltic A.jpg

 

Bo-Bo wheel arrangement should help with high speed, and perhaps the Mk1 trailer rakes would be articulated 4-car sets too...

 

 

BR had already obtained experience with top and tail operation already by the early 60s with the Blue Pullmans, up to 8 cars at 90mph and a big influence on the eventual HST.  Pullman type Mk2 air conditioned type stock would be necessary because the sliding ventilators of mk1s would have been a nightmare at 125, never mind 140, and the set would have had to be permanently coupled with fixed drawgear.  The main limitation would not have been providing the power, but finding bogies for it to run on; nothing outside Japan ran at anything like this sort of speed in those days and a new bogie would have had to have been designed from scratch for both loco and coaches.  The 100mph commmonwealths or B4s would have not been adequate beyond 120mph (I have timed a B4 bogied train hauled by a 50 at 114mph in a mk1; the noise was impressive and the air pressure buffetted the interior worryingly but the coach rode fine).  In practice I doubt more than 120mph could have been obtained in the 60s anywhere in the UK in normal timetable running, or in Europe for that matter!

Edited November 2, 2017 by The Johnster

[34theletterbetweenB&D]

...  In practice I doubt more than 120mph could have been obtained in the 60s anywhere in the UK in normal timetable running, or in Europe for that matter!

But BR had inherited a complete train design that had already been tested up to that speed. Build Gresley 'Coronation' sets, there's the eight vehicles in articulated pairs for the job. BR never reinstated the full sets in service, but the first class twins were regulars on the Talisman service until 1962.

[Ramblin Rich]

Not sure what the Chief Civil Engineer would have thought of Kestrel doing 125 or Bo-Bo Deltics either. I think it was around then the 86s were pounding the tracks and the idea of axle hung motors at high speeds were starting to become a liability.

[Satan's Goldfish]

It would be the 'Bentley' of HSTs - adequate power plus 50%. I guess what we need now is an 8-TC with Pullman windows and livery as well as bogies that are good for 140mph.

Started working on it in work, but you'll have to wait until Monday now modifications required following the comments above though.

[scots region]

Not sure what the Chief Civil Engineer would have thought of Kestrel doing 125 or Bo-Bo Deltics either. I think it was around then the 86s were pounding the tracks and the idea of axle hung motors at high speeds were starting to become a liability.

Probably something along the lines of, ‘There must something very interesting in the Doncaster water supply’.

[cheesysmith]

The talk of a high speed Bo Bo deltic why do you need two engines? The engine in the baby deltic was a 9 cylinder turbo, the deltics were 18 cylinder non turbo. A 27 cylinder turbo would be good for 3300bhp. The 18 cylinder version in use in the navy was turbo and intercooled, and gave 3700bhp (BR insisted on derating the engines used in the deltic for longevety and reliability. Stories still go round of deltic just before withdrawal making more than 3300bhp).

[Flying Pig]

Or appropriately geared pairs of single cabbed Deltics either end, of BoBo configuration (they didn't need to be Coco at 99T, and reducing the bogies to Bo and losing a cab makes them lighter yet)? There's 6,000 hp which should be good for 140mph on a circa 500 ton all up set, so 8 mk1 coaches as the filling (for a truly exciting ride) and three out of four engines likely to be available at worst...  yeeeeha!

Been there, done that, got the antimacassar.

[The Johnster]

The idea of a Gresley Coronation articulated set in daily service at these sort of speeds is not a flyer, sorry.  Of course, it is perfectly allowable in a thread about imaginary locos, but my concept of imaginary is for locos or stock that would have feasibly run in their intended role.  A very fast run on one occasion does not qualify it as suitable for regular service, though I accept that the Gresley bogie, dating to GNR days, was and is a very good, if heavy, design that functioned well at the higher end of steam loco (and Deltic) operation.

[rockershovel]

The idea of a Gresley Coronation articulated set in daily service at these sort of speeds is not a flyer, sorry.  Of course, it is perfectly allowable in a thread about imaginary locos, but my concept of imaginary is for locos or stock that would have feasibly run in their intended role.  A very fast run on one occasion does not qualify it as suitable for regular service, though I accept that the Gresley bogie, dating to GNR days, was and is a very good, if heavy, design that functioned well at the higher end of steam loco (and Deltic) operation.

Following the logic, how about a Coronation articulated set with a single-ended Deltic, or something of the sort, at either end; a sort of proto-HST 100?

[The Johnster]

Yes, that would have worked, but it is pretty unlikely to have been built, the Gresley stock offering no real advantage over mk1s.  A Deltic powered train of this sort is more likely to have been composed of articulated (to save weight and improve the ride) mk1s or earlier mk2s, possibly with sets of airconditioned mk2s in the early 70s before HSTs proper came on the scene.

 

But, until the advent of the HST 125s, BR seemed not to be interested in the concept of articulation, probably because most passenger operation still followed the 'traditional' concept of trains which could be made up to requirements of individual vehicles, of which spares and strengtheners were kept at depots.  As steam ended and more main line trains were loaded to a maximum that diesel or electric traction could run the timetable with at a known level of maintenance, in other words as loco performance became more predictable, the idea of 'set formation' permanently or semi-permanently coupled trains became more attractive, and the modern railway consists almost entirely of multiple unit or set trains of this sort, even where separate locomotive haulage is used.

 

It is perhaps a little surprising that articulation has not made a resurgence in such circumstances. it looks initially to have a lot of advantage and, if the train is to remain coupled, few drawbacks.  It made an appearance in the APT, which cannot have improved it's image but articulation was not one of that project's many problems.  Articulation enables wider and more passenger friendly gangways, better riding, and saves weight, which in itself improves performance and saves fuel especially with diesels.  But there is an important downside; axle loading and track wear is increased, especially in fast running.

[BernardTPM]

Following the logic, how about a Coronation articulated set with a single-ended Deltic, or something of the sort, at either end; a sort of proto-HST 100?

 

You mean like my earlier post here? (Only the loco is pre-war too).

[Coryton]

It is perhaps a little surprising that articulation has not made a resurgence in such circumstances. it looks initially to have a lot of advantage and, if the train is to remain coupled, few drawbacks.  It made an appearance in the APT, which cannot have improved it's image but articulation was not one of that project's many problems.  Articulation enables wider and more passenger friendly gangways, better riding, and saves weight, which in itself improves performance and saves fuel especially with diesels.  But there is an important downside; axle loading and track wear is increased, especially in fast running.

 

Why does articulation enable wider gangways? There are plenty of non articulated trains in the UK now with gangways almost as wide as the body.

 

I believe that the increased axle loading is what has prevented articulation in the past, though it looks as if it's coming in with some of the new Anglia trains.

[BernardTPM]

Why does articulation enable wider gangways? There are plenty of non articulated trains in the UK now with gangways almost as wide as the body.

 

Articulation makes it easier to have wide gangways as the coaches generally have a common pivot which minimises swing over on reverse curves.

 

Eurostar TGV based sets are articulated and have been running for over 20 years.

[PhilJ W]

The problem with articulation at high speeds is braking, fewer wheelsets means less braking power. The Gresley articulated stock is a case in point, special powerful braking systems had to be developed for it. Most of the problems fortunately can now be overcome by modern brake technology but 80 years ago was quite an achievement.

Edited November 4, 2017 by PhilJ W

[runs as required]

The problem with articulation at high speeds is braking, fewer wheelsets means less braking power. The Gresley articulated stock is a case in point, special powerful braking systems had to be developed for it. Most of the problems fortunately can now be overcome by modern brake technology but 80 years ago was quite an achievement.

I hadn't thought of the braking aspect of articulation (wheels and discs per tonnage of train) - only the issue of a set being taken out of service with one bogie failure.

 

Actually superficially surfing through all nearly 70 pages of this popular thread since May 2010 (!) made me realise what an open ended number of variables exist in mech. eng. design. and  how the strengths and weaknesses of individual mech. engs. play such a significant part.

 

I have had my eyes opened over the last 40 years from the earliest 'optimising' computer prgrams applied to traffic network modelling to the current A.I. software that generates architectural form and detail contract delivery. This is increasingly now making the architect, the various engineers and the project manager merely by-standing intermediaries in dealing with the client.

In my field it doesn't necessarily result in mediocrity - the Kings Cross concourse or the Sage Gateshead (which many musicians claim has the best acoustic in Britain) would not have been possible without contemporary forms of A.I. algorithms.

 

Is it the same in 'imagineering' new designs in transportation?

 

dh

Edited November 4, 2017 by runs as required

[Clearwater]

The problem with articulation at high speeds is braking, fewer wheelsets means less braking power. The Gresley articulated stock is a case in point, special powerful braking systems had to be developed for it. Most of the problems fortunately can now be overcome by modern brake technology but 80 years ago was quite an achievement.

Oh so that's why Gresley needed to do all those "braking tests"....

[cheesysmith]

Articulation has good and bad points.

 

Good-Fewer heavy expensive bogies, so lower mass and cheaper trains. If the train is connected as a whole, better ride (a la TGV) because the bogies are allowed to do what  movements needed without affecting the body.

 

Bad-Fewer wheels in contact with the rail, reducing available grip. The less wheels you have in contact with the rail, the more work those fewer wheels have to do to slow the train (and grip when applying power). Also, the higher the axleload per wheel.

 

The APT is a good example. The shared bogies had the coach mounting points and pivot points outside the bogie, so vertical movements were amplified between adjacent coaches. Also, the APT brakes were capable of stopping it from 155mph within the same distance of a conventional 100mph train. But BR had to make allowances for low grip and a train running with a certain percentage of the brakes isolated, so limiting the APT to 125MPH. If the train had been built with normal bogies, the extra wheels in contact with the rail would have allowed higher speeds because of better braking. The total train mass may have been more but the ride would have been better. The pendos are better in the fact that the motors allow better braking, and being 3 phase motors, as soon as the wheels slip, the motor torque drops to nil, resulting in self correcting wheel slides. The best high speed train would have every axle powered (except maybe the first, to allow a independent wheels for ABS use) with body mounted motors and the equivalent braking HP of about 1000BHP per axle. Such a light weight EMU would allow even higher speeds within present signal distances.

[Dr Gerbil-Fritters]

Here's one I did earlier.  A streamlined skip, with MKIIIs and a DVT.

 

 

Designed as a replacement for the sh1te meridians on the EMT to St Pancras in lieu of the electrification which has been abandoned.  Thinking on, it might need a super skip at both ends to maintain high point to point and acceleration?  

Edited November 4, 2017 by Dr Gerbil-Fritters

[Suzie]

Here's one I did earlier.  A streamlined skip, with MKIIIs and a DVT.

 

post-238-0-53289500-1351174799.jpg

 

Designed as a replacement for the sh1te meridians on the EMT to St Pancras in lieu of the electrification which has been abandoned.  Thinking on, it might need a super skip at both ends to maintain high point to point and acceleration?  

 

Just give it a 'B' unit so it can't be borrowed for something else!