Rapido/Locomotion Models GNR Stirling Single

[Horsetan]

.....There is the scenario that Rapido could  make an absolutely accurate model of No 1 but we could never run it due to the complete lack of clearances at 4mm to the foot.  Maybe next time a Millholme kit comes up on Ebay I ought to bid on it to see the alternative......or maybe not..

 

The expensive salivating over the Rapido Single doesn't seem to have hurt demand for the ancient Kitmaster kit.

[billbedford]

No, sorry Bill - as soon as I saw the EP photo I knew that something wasn't right; it said LNWR, not GNR, to me.

 

Admittedly, it wasn't until I saw the side-by-side photos (above) that I managed to identify the features that explained my reaction - but I knew it wasn't right straight away.

 

It was the too-flat curve down from the smokebox to the cylinders that was the chief give-away.

 

....... and I know NOTHING whatsoever about Mr. Stirling's output, beyond having seen many photos of No.1 over the last 50+ years.

 

Regards,

John Isherwood.

 

 

No, not at all.  The EP struck me as wrong because I am familiar with the appearance of the prototype (as a frequent visitor to Shildon - those were my photographs I used, and I've taken many of them!), but thanks for trying to tell me why I think the way I do!

 

This may be an historic first, but I agree with Mr Isherwood!

 

But you are both comparing photographs. It is a well known phenomena amongst people who actually build models that errors and misalignments are easier to spot on a photograph that on a 3D object. It is  something that's inherently different in the way brains 'read' 2D graphic images and 3D objects.

[Guest Midland Mole]

I fear this thread is rapidly descending into Oxford Dean Goods & Stanier Mogul territory, I seriously despair sometimes....

Edited July 31, 2017 by Midland Mole

[cctransuk]

...... people who actually build models that errors and misalignments are easier to spot on a photograph that on a 3D object. .....

 

Bill,

 

Suffice to say that the number of models that I have built is counted in four figures.

 

It may be easier to spot an error in a photo - but only if the error exists in the first place!

 

In this case, there are several striking errors which would not require a photo to spot them, if I had the model in front of me.

 

Surely you are not suggesting that, if the model is produced largely as per the EP, no-one would spot the issues highlighted above unless they took a photo of the model?

 

None of this is to suggest that the issues were avoidable - only that they are rather noticeable.

 

Regards,

John Isherwood.

[Edwardian]

But you are both comparing photographs. It is a well known phenomena amongst people who actually build models that errors and misalignments are easier to spot on a photograph that on a 3D object. It is  something that's inherently different in the way brains 'read' 2D graphic images and 3D objects.

 

No, I am saying "I looked at the EP and thought "It doesn't look right; something is throwing out the proportions of the front end", then I looked at my store of recent photographs and said "Ah, that's why it looks wrong, the front footplate is at completely the wrong height relative to the cylinders".  If I had known you would raise this point, Bill, I might have prefaced my thoughts with "Based upon my familiarity with the full size locomotive and my memories of its appearance .... ", but, in my internal dialogue, I'd rather taken that as read!

 

With the model, I can only go off photographs, but the differences between the model and the prototype, particularly the height at which footplate meets the cylinders, are pretty damn obvious; the difference in height is very marked, from a number of angles that we have now seen.  So I dare to suggest it will prove to be equally obvious in the flesh.

 

Anyway, what does it matter what my or Mr Isherwood's mental processes were, the model is still wrong in this regard and it still makes the front end look "off"?!?

 

Which is a shame, IMHO.

 

We may have to live with this, but it would be a shame if some of the characteristic appearance of these locomotives is sacrificed due to some misguided insistence that it must go round train-set curves.  If that is indeed the reason.  I don't know why this error is apparently included.  That is why I have asked about it here, but neither Locomotion nor Rapido have yet commented.

 

A little effort at communication and some frankness would go a long way for me, e.g. "sorry Guys, we know this aspect isn't perfect, but we had to do it this way because ....", or, even better, "we hear what you're saying and we'll see what we can do ..."

 

I will add that I have nothing against train-set curves per se, people should build what suits them, what they can fit in, and what they damn-well want, so far as I am concerned, but I don't think those using tight radii, for whatever reason, should insist that everything made should necessarily be suitable for them.  I would object where the accuracy and integrity of a model is sacrificed to accommodate tight radii, that is all.  But, I am forced to speculate as to what is going on with the front end of the Rapido model, because no comment has yet been forthcoming.  All I can say is that it is, very noticeably in my view, wrong. 

[CF MRC]

My word, what a frenzy! There is clearly an assembly error in the EP. That might yet also be an inherent design error. However, why not let Rapido work on it? When I made my 2mm scale 8' single I noted that many of the dimensions came out with a very pleasing geometrical simplicity. The Victorian engineers cerainly new how to make a pleasing design. Stirling singles were generally built in pairs, so you need to take great care comparing between photos.

 

The front end appearance is absolutely critical for a Stirling single (indeed, any loco). The Rapido engine currently has more of a LNWR 'Cornwall' look to it, with dare I say it, a slight tendency to 'saggy boobs' as currently configured. The talk of the engine being easier to model in P4 with scale flanges is not particularly valid, as the limiting factor is the horizontal clearance to the splashers, not really the wheel diameter. In that case OO is much easier. Having the cylinders too low actually makes the problem rather worse. It would be very difficult indeed to make one of these engines in N gauge.

 

The classic photo below was taken by Craig Tiley (courtesy RM).

 

Tim

[Edwardian]

Tim, I accept what you say, though I, for one, feel pretty frenzy-free on the issue.

 

My reason for raising it again was to see what the story was, as now a second EP shot has come with the same issue, and no comment has been made by Locomotion or Rapido.  As a result, I don't know whether to expect the finished loco to have this "off" face or not.

 

Is it wrong to mention it at this stage? Well, it might be something that Rapido can fix and would anyway have fixed, but I am not to know that.  On topics dealing with other releases, critics have been condemned for not pointing out apparent issues soon enough, so it somehow becomes their fault that a manufacturer goes into production with a glaring error! 

 

Out of an abundance of caution, I'd rather have the point ventilated at this stage.

 

This way at least Locomotion/Rapido get some feedback that these disparities strike a number of us as pretty obvious and affect the overall look of the thing. They will then do as they think fit, and I am confident that Rapido, of all manufacturers, will be given the benefit of the doubt when it comes to any necessary engineering compromises, if that's what we're looking at here.

[davknigh]

When you think about it the Rapido design team are trying to make a model of a locomotive that was designed to go around curves that scale out to be 833" to go around curves of 18" and still look like the real thing while running with over size flanges and a narrow track gauge. That they have done as well as they have is highly commendable. I suspect that they are still working to bring things up a notch or two but to expect instant reaction to comments like "it looks wrong" is expecting a bit much. Give them some more time, give helpful comments by all means but be constructive. Something like "it looks a bit LNWR" may mean a great deal to individuals but to a design team, not so much.

 

Cheers,

 

David

[G-BOAF]

Sorry, all this talk of trainset curves - we are dealing with a situation where the cylinders and motion appear too LOW. If there was a curve issue, we would expect to see things RAISED to provide clearance for wheels etc.

If the running plate behind the cylinders is too high, again, I can't see any reason why this is for clearance issues (the running plate is way above the bogie wheels).

Sorry if this sounds a bit sharp, but can someone who is suggesting clearance are an issue and a reason for the cylinder issues, explain, with the laws of physics, how lower cylinders will help with clearances?

I’m also aware that we are speculating, and a response from the excellent Rapido team would be helpful, either confirming they still need to fix it, or why the 'error' is present.

 

Cheers

[Darius43]

I remember reading a highly entertaining article about a trip to the UK by the owner of Rapido Trains and thinking what a totally great guy he is and wasn't it nice that he had decided to provide us with models of UK trains that are as excellent as those that Rapido makes of Canadian and US trains.

 

After ploughing through the pedantry on this thread I wouldn't blame him for giving up on us altogether.

 

Darius

[cctransuk]

Something like "it looks a bit LNWR" may mean a great deal to individuals but to a design team, not so much.

 

Quoted out of context - I also said "It was the too-flat curve down from the smokebox to the cylinders that was the chief give-away".

 

I think that is sufficiently clear, don't you?

 

Regards,

John Isherwood.

[Andy Hayter]

 

If the running plate behind the cylinders is too high, again, I can't see any reason why this is for clearance issues (the running plate is way above the bogie wheels).

Sorry if this sounds a bit sharp, but can someone who is suggesting clearance are an issue and a reason for the cylinder issues, explain, with the laws of physics, how lower cylinders will help with clearances?

I’m also aware that we are speculating, and a response from the excellent Rapido team would be helpful, either confirming they still need to fix it, or why the 'error' is present.

 

Cheers

 

I think there may be several clearance issues and focusing on the front bogie and the cylinders may not be the  issue.

 

One of the pictures of No.1 at York in post #570 seems to show a tight clearance between the foot plate and the connecting rod.  This would be improved by lowering the cylinders.  

 

I agree however that some comment from the Rapido team would perhaps allow us all to get over the issues we perceive. 

[dibber25]

I've joined this debacle late, having told myself I wouldn't join it at all. No one seems to have noticed that the main assembly is a die-casting. Were it an etched kit, you could probably get the slidebar 'behind' the 5thou brass valance. As it is a solid casting there's no place for the slidebar to go other than below it. It has nothing to do with flanges or clearances. Or am I missing something? Sorry to see the rush to say "something looks wrong" but as I've said elsewhere (in the Dean Goods thread) - if you're seeing something in plastic and metal there aren't many changes that can be made. We have to trust that the designer has got as near as he can to the original, whilst working at 1/76th the size in cast metal and plastic rather than steel sheet.  (CJL)

[Miss Prism]

As it is a solid casting there's no place for the slidebar to go other than below it.

 

Indeed. But, just a thought:

 

 

Btw, it's pleasing to note ashpans are now back in fashion amongst RTR loco designers.

[CF MRC]

That is how I made my 2mm version, although the top of the crosshead does not then need to be modelled in full.

 

Tim

[cctransuk]

I've joined this debacle late, having told myself I wouldn't join it at all. No one seems to have noticed that the main assembly is a die-casting. Were it an etched kit, you could probably get the slidebar 'behind' the 5thou brass valance. As it is a solid casting there's no place for the slidebar to go other than below it. It has nothing to do with flanges or clearances. Or am I missing something? Sorry to see the rush to say "something looks wrong" but as I've said elsewhere (in the Dean Goods thread) - if you're seeing something in plastic and metal there aren't many changes that can be made. We have to trust that the designer has got as near as he can to the original, whilst working at 1/76th the size in cast metal and plastic rather than steel sheet.  (CJL)

 

Chris,

 

Certainly a difficult prototype, but not impossible to get right, surely?

 

Given that the prototypical upper slidebar is hidden by the valance, does it even need to exist in model form? Could not the upper edge of the crosshead run in a slot cast into the running plate?

 

Done that way, the mazak running plate would appear to cover the upper slidebar in its correct location, and the curved platework down from the smokebox to the cylinders could take its correct form.

 

That's how I would have done it, anyway.

 

Regards,

John Isherwood.

 

PS. Miss Prism - great minds think alike !!

Edited July 30, 2017 by cctransuk

[dibber25]

I doubt a cast slot in a mazak casting would be smooth enough to run a crosshead, without some delicate machining. It's surely the sort of location that invites flash. It would also put the crosshead right on the interface between 'body' and 'chassis' so that separating the two would cause the crosshead to drop out. Anyway, only the designer knows what parameters he had to work in with the design, and knowing him, if there was a way to have done it differently, he would have done so. If I had to choose two locomotives which I would have advised a manufacturer not to attempt in RTR, it's the Stirling Single and the L&B Manning Wardles......(CJL)

Edited July 30, 2017 by dibber25

[Clearwater]

I assume the use of diecast is to give the model some mass. Presumably if diecast is a less flexible material than plastic to work with and mould, then its an example of a compromise to get a model that'll actually pull more than its own tender...

 

David

[James Harrison]

It looks a lot more like Stirling's masterpiece than my current model of a GNR 4-2-2 (which started life as a Bachmann 'Emily' and was slightly hacked up...)

 

Clearances on the prototype fall into gnat's whiskers territory so it was pretty much a certainty that some compromises would be necessary (see also the Bachmann GNR Atlantic with the curved connecting rods and coupled wheelbase).  With these engines you either build something that looks good but doesn't work (can't speak for everybody but I certainly don't have room for 20' radius curves which a true-to-scale model would need) or accept the limitations placed by materials and scale and compromise accordingly.  How thin a plastic footplate is practical, before the material becomes so fragile as to be untenable for instance?  Yes you could use brass but then that increases the amount of assembly and skill necessary with a corresponding price rise.  Anything can be done, for a price.... so how many of us would be prepared to shell out £400 or £500 for a perfect Stirling Single?  I wouldn't..... nice model but beyond my means. 

[cctransuk]

I doubt a cast slot in a mazak casting would be smooth enough to run a crosshead, without some delicate machining. It's surely the sort of location that invites flash. It would also put the crosshead right on the interface between 'body' and 'chassis' so that separating the two would cause the crosshead to drop out. Anyway, only the designer knows what parameters he had to work in with the design, and knowing him, if there was a way to have done it differently, he would have done so. If I had to choose two locomotives which I would have advised a manufacturer not to attempt in RTR, it's the Stirling Single and the L&B Manning Wardles......(CJL)

 

Sorry Chris, but mazak cast in a precision mould will provide a far better bearing surface than stamped and plated brass, or some other relatively soft sheet metal.

 

Moreover, cast mazak has been sucessfully used for crossheads since Hornby Dublo days - and before; (Hornby, Bassett Lowke, etc., etc.).

 

There would be no need to have the body / chassis interface on the upper face of the crosshead; the cylinders could be logically incorporated into the body, as there is no apparent 'split' between the two on the prototype.

 

To release the body? Simply unscrew the crankpins - no different to removing the speedometer crank from the rear driving wheel of, say, a Bulleid Pacific.

 

To an engineer, no problem of this type is incapable of resolution - it just needs creative thinking.

 

We do not know why the EP looks as it does - it may well be poor assembly - but I do NOT believe that it is impossible to produce the Stirling Single with the cylinder / valance in their correct relationship.

 

I would expect the designer to regard the two prototypes to which you refer as a challenge - not an excuse for avoidable compromise.

 

Regards,

John Isherwood.

[MikeTrice]

A comparison of the EP against the prototype show that the body is largely correct. The problem appears to be that the cylinders and slidebars are too low. This may well be to provide clearance for the connecting rod to clear the diecast footplate.

 

[cctransuk]

A comparison of the EP against the prototype show that the body is largely correct. The problem appears to be that the cylinders and slidebars are too low. This may well be to provide clearance for the connecting rod to clear the diecast footplate.

compare3 - extract.jpg

 

Interesting ! It is clear that a cast ridge on the underside of the running plate would serve admirably as the upper slidebar - problem solved.

 

Regards,

John Isherwood.

(Former Civil Engineer - who knows little about Mechanical Engineering beyond what 50+ years of railway modelling has taught him).

[Sir Hadyn]

Does anyone know when the preserved No.1 stopped being kept in working condition? I have seen some videos of it running on the GCR in the mid-80s, but when did it become a static exhibit?

Alex

She last steamed in 1985 for the NRM's 10th anniversary and ran in the North Yard with Mallard.

[Miss Prism]

The problem appears to be that the cylinders and slidebars are too low. This may well be to provide clearance for the connecting rod to clear the diecast footplate.

 

Yes. It's a tricky situation.

 

[davknigh]

Quoted out of context - I also said "It was the too-flat curve down from the smokebox to the cylinders that was the chief give-away".

 

I think that is sufficiently clear, don't you?

 

Regards,

John Isherwood.

Erm, no. Sorry John but for anyone making a pattern or sinking a die a comment like yours is not useful. If you said the radius should be xx or something quantifiable then yes, useful but too flat????

 

Cheers,

 

David