Lecorbusier Posted July 15, 2018 Share Posted July 15, 2018 Still on the topic of haulage or at least the capacity to haul, a bit of fun was had last night at the club with the Bachmann Jubilee again. This time it was a record thirty coaches, 19 with brass axle bearings the rest with tuned axle holes and plastic compatable grease. The Jubilee started the train no problem and only slipped slightly pulling the train round the 6ft curves at the layout ends. The record will stand for now as I don't want to do any damage to the loco after it's detailing is finished. That's an end to the silliness. Wharfeside was getting some more scenic formwork done last night too and once the overbridge has had it's final weathering and is fixed in place I'll be able to blend in the top surface and add the grass. Dave. Dave, I don't suppose you've considered posting this video on Wright writes ? Might generate a little discussion! Link to post Share on other sites More sharing options...
davefrk Posted July 15, 2018 Author Share Posted July 15, 2018 Apologies for the rash of ratings. I’ve read through this topic a couple of times and the photos of the track work just blows me away - not that everything else isn’t as equally impressive! Hi Tortuga, thanks for your comments much appreciated. Just your comment above would have done and saved yourself some time clicking buttons. Regards, Dave. Link to post Share on other sites More sharing options...
davefrk Posted July 15, 2018 Author Share Posted July 15, 2018 Dave, I don't suppose you've considered posting this video on Wright writes ? Might generate a little discussion! Hi Tim, yes I did post a similar but poorer clip a few weeks ago - 19 coaches, It does amuse me that some people complain about their locos only hauling a few coaches or wagons and the advice is to add loads of weight to the loco completely ignoring the rolling stock and how free running or otherwise it is. All the best, Dave Franks 1 Link to post Share on other sites More sharing options...
RMweb Gold Sandpiper Posted July 16, 2018 RMweb Gold Share Posted July 16, 2018 (edited) There is something very convincing about the movement of the trains in your videos. I think perhaps it is a combination of the very smooth running, the lovely long sweeping curve and the realistic speeds. They look like real trains and they look like they have the weight and momentum of real trains. This one in particular makes me feel as though I am really there on a bridge watching a real train even though the surrounding landscape is far from finished. Because the movement is so convincing my brain happily adds the missing details including the smoke and steam. Kit built Clan Mackintosh hauling the Waverley set, standing in for the usual Jubilee or Scot. Edited July 16, 2018 by Sandpiper Link to post Share on other sites More sharing options...
RMweb Gold Enterprisingwestern Posted July 16, 2018 RMweb Gold Share Posted July 16, 2018 Hi Tim, yes I did post a similar but poorer clip a few weeks ago - 19 coaches, It does amuse me that some people complain about their locos only hauling a few coaches or wagons and the advice is to add loads of weight to the loco completely ignoring the rolling stock and how free running or otherwise it is. All the best, Dave Franks Another problem being that some people add weight willy nilly to a loco, and then wonder why it pulls less than before, there's an art to it! Mike. Link to post Share on other sites More sharing options...
Lecorbusier Posted July 16, 2018 Share Posted July 16, 2018 Hi Tim, yes I did post a similar but poorer clip a few weeks ago - 19 coaches, It does amuse me that some people complain about their locos only hauling a few coaches or wagons and the advice is to add loads of weight to the loco completely ignoring the rolling stock and how free running or otherwise it is. All the best, Dave Franks Presumably for true prototypical mimicry you would need nice free running but also significant inertia in the stock? Then you could achieve a degree of wheel slip on starting if you aren't gentle enough on the regulator but once things are moving all is good? Presumably having two much weight on the loco would prevent wheel slip and over play braking as well? I thought the way your loco started on the long train matched the prototype quite nicely (though with far too many coaches) .... presumably by weighting the stock a little more you could bring down the number required to cause a degree of slippage - it would be interesting to know how the train would be affected by a 1:100 gradient. Link to post Share on other sites More sharing options...
RMweb Gold Regularity Posted July 18, 2018 RMweb Gold Share Posted July 18, 2018 Presumably for true prototypical mimicry you would need nice free running but also significant inertia in the stock? How are you going to do that, then? The train will be travelling at 1/76 of the prototype speed, e.g a scale mile a minute rather than an actual mile a minute. The volume of the train, which will have a large impact of its mass, has been reduced by 1/76 in each of three dimensions. Inertia is mass times the square of the velocity, but the mass is 1/(76 * 76 *76) of the original, and the square of the velocity will be 1/(76 * 76) of the original, so if the model train uses exactly the same materials as the prototype with exactly the same density, the upshot is that the inertia will be 1/76 of the “real” thing: to get a realistic level of inertia, a loaded 16t mineral wagon would have to have a mass of about a quarter of a ton! Then the rails would need to be a lot bigger to carry the weight, so goodbye to any scale fidelity that way! And no way would such a massive wagon run at all with pin-point axles running in coned bearings: like the real thing, parallel or roller bearings would be required. Yes, a reasonable amount of weight in rolling stock helps, but ultimately some form of inertia simulation is required, be that via DCC settings, an electrolytic capacitor paired with a (variable) resistance, or careful and slow twisting of the control knob. The thing is, you can’t scale physics: it still works in the same way, but some things are affected by a linear reduction, some by a square reduction and others by a cubic reduction. Glib statements like “significant inertia” show a lack of understanding and help no one. Mimicking the prototype requires a different approach, be that control circuitry or expert control. (Expert? I once saw a friend’s twelve year old daughter start a train on an 00 layout with every semblance of mass and inertia. When I asked if she had practiced this a lot, she said, “No. It’s just how real trains move, because they are heavy.”) Even de-coupled flywheels (Dynadrive - lovely!) can’t get near the full effect for a full train, but on-board storage (DCC) and battery power (radio control) can work well in conjunction with electronic simulation to create the right impression. I’m sorry if that sounds blunt, but being reasonably widely read, I know full well how much I don’t know (and just how little I do know), and am acutely aware of the damage that can be caused by throw away remarks based on insufficient understanding. (Knowledge in this case extends to A level physics back in the days when grades were normatively marked, so quite a long while ago*, but in this instance, was covered in the 4th year - year 10, nowadays - if not earlier. Don’t get me started on “hollow” flywheels...) * 1983. 1 Link to post Share on other sites More sharing options...
Lecorbusier Posted July 19, 2018 Share Posted July 19, 2018 (edited) No worries Simon, Not intended as throw away ... simply asking a question .... Interested by your answer. Looking at Dave's longer train, I thought it visually 'felt' like it had real weight and so 'looked' more realistic to my eyes. Simply wondered if this level of effect might be achievable by using fewer but heavier coaches (what I termed mimicing the prototype). Your response would suggest not? Unfortunately what I was talking about was much more 'touchy feely' than scientific and the terminology used was perhaps too specific? Tim Edited July 19, 2018 by Lecorbusier Link to post Share on other sites More sharing options...
mightbe Posted July 19, 2018 Share Posted July 19, 2018 (edited) I think in modelling terms there's an implicit consensus that we speak of physics, motion, etc. as "apparent", not absolute (since attempting to scale things goes nowhere). Edited July 19, 2018 by mightbe Link to post Share on other sites More sharing options...
davefrk Posted July 19, 2018 Author Share Posted July 19, 2018 (edited) I think a lot of this inertia talk is over me head lol. The loco in the clip is a basic Bachmann Jubilee with no extra weight added, only the wheels have been changed for Gibsons and a Mashima motor fitted. At full chat it goes nicely with that load but cut the power and the train pushes the loco about 20''. Even with the usual nine coach Waverley set the loco can be pushed over 10'' so there is some inertia there. As you can see the Jub can start the 30 coaches and pull away without a slip if driven carefully but wind it up too quickly and the wheels spin. There are no gradients on Wharfeside but there are 6 foot curves at the ends which can slow an excessively long train. The tests were to show the need for free running stock rather than weighting the loco and possibly overheating the motor trying to haul 'stiff' coaches, in my mind that is mechanical cruelty. I like to have a train running round whilst I'm working sometimes for hours and the motors do get luke warm but never hot. I got rid of all the DS10, D11 and D13s years ago.... Dreadful things. I think 'apparent' inertia is probably more correct, it's the visual thing with a model going along at a steady realistic speed giving that look of weight. A combination of things coming together to produce the effect is what I try to get right, doesn't always work but Hey Ho. Dave Franks. Edited May 7, 2022 by davefrk 2 Link to post Share on other sites More sharing options...
RMweb Gold Regularity Posted July 19, 2018 RMweb Gold Share Posted July 19, 2018 (edited) That 10" of overrun is probably representing 10 chains! A combination of things coming together to produce the effect is what I try to get right, Quite possibly the quintessential definition of railway modelling doesn't always work but Hey Ho. Assuming you go back and try again (eventually!), quite possibly the quintessential definition of a railway modeller... Edited July 19, 2018 by Regularity 2 Link to post Share on other sites More sharing options...
davefrk Posted August 15, 2018 Author Share Posted August 15, 2018 Not much to report really, scenery is ongoing with the groundwork beyond the roadbridge to hide the fiddleyard taking shape. All the Tortoise pointmotors are now fitted with TV suppressors and the DAB radio no longer crackles when the points are changed. Something like this may also help those whose servos twitch when a loco passes near, electric motors will always have sparks at the brushes and pickups which can give interference but a suppressor will reduce the effect considerably as proved to me with the DAB radio. Some videos were taken last week with different locos but I've yet to upload them to Youtube. Dave. 2 Link to post Share on other sites More sharing options...
mike morley Posted August 15, 2018 Share Posted August 15, 2018 Have to admit that I'd long assumed modern electric motors were 'clean' enough for interference to be a thing of the past. I would also have assumed the 'D' of DAB would have rendered them immune to such interference anyway! We live and learn! Link to post Share on other sites More sharing options...
RMweb Gold Joseph_Pestell Posted August 15, 2018 RMweb Gold Share Posted August 15, 2018 Have to admit that I'd long assumed modern electric motors were 'clean' enough for interference to be a thing of the past. I would also have assumed the 'D' of DAB would have rendered them immune to such interference anyway! We live and learn! In my experience, quite the reverse. Digital TV seems much more vulnerable to interference than analogue. Link to post Share on other sites More sharing options...
RMweb Gold Joseph_Pestell Posted August 15, 2018 RMweb Gold Share Posted August 15, 2018 (edited) It's all very well trying to calculate a proper weight for coaches/wagons to provide inertia - but we don't have a vacuum brake to play with. Going way back to the 1950s, Ken Northwood of North Devon fame, managed very long trains of short wheelbase wagons round a 2ft3in return loop. They must have been very free-running. Edited August 15, 2018 by Joseph_Pestell Link to post Share on other sites More sharing options...
jrg1 Posted August 16, 2018 Share Posted August 16, 2018 It's all very well trying to calculate a proper weight for coaches/wagons to provide inertia - but we don't have a vacuum brake to play with. Going way back to the 1950s, Ken Northwood of North Devon fame, managed very long trains of short wheelbase wagons round a 2ft3in return loop. They must have been very free-running. I believe his locomotives were heavily weighed, and had Pittman motors Link to post Share on other sites More sharing options...
Denbridge Posted August 16, 2018 Share Posted August 16, 2018 I believe his locomotives were heavily weighed, and had Pittman motorsand very free running stock apparently. Link to post Share on other sites More sharing options...
Denbridge Posted August 16, 2018 Share Posted August 16, 2018 and very free running stock apparently. and very free running stock apparently.i recall Iain rice saying that when the 72xx started the long coal train on a gradient, the lights dimmed all across Devon. LOL Link to post Share on other sites More sharing options...
Porcy Mane Posted August 17, 2018 Share Posted August 17, 2018 (edited) Dunno how it is, I only found this thread a wee while ago Dave, Anywez, the Ammonia's are looking good. P Edited August 17, 2018 by Porcy Mane Link to post Share on other sites More sharing options...
Killybegs Posted August 17, 2018 Share Posted August 17, 2018 Dunno how it is, I only found this thread a wee while ago Dave, Anywez, the Ammonia's are looking good. P Late again! Link to post Share on other sites More sharing options...
Porcy Mane Posted August 17, 2018 Share Posted August 17, 2018 Late again! As ever. Link to post Share on other sites More sharing options...
davefrk Posted August 17, 2018 Author Share Posted August 17, 2018 Dunno how it is, I only found this thread a wee while ago Dave, Anywez, the Ammonia's are looking good. P How on earth could you have missed it, silly boy. Dave. Link to post Share on other sites More sharing options...
Porcy Mane Posted August 17, 2018 Share Posted August 17, 2018 silly boy. As ever. Looks like you've gone down the route of solution tanks as opposed to liquified (frosties). https://flic.kr/p/MWVFys P Link to post Share on other sites More sharing options...
Buhar Posted August 17, 2018 Share Posted August 17, 2018 Hi Dave, I've been popping in to view progress over the last couple of years and pick up useful little tips (eg microswitches for Seeps) many thanks indeed. Your trackwork is excellent, I find the almost continuous curves on the main line very realistic. Am I remembering correctly that you have a ruling radius of 6ft (presumably transitioned)? Does that apply to off-scene areas too? Which leads me on to coach coupling, what do you use and how close together are the buffers on the straight? The running you're achieving as shown in the videos makes all the effort on track and stock worthwhile. Link to post Share on other sites More sharing options...
Jub45565 Posted August 18, 2018 Share Posted August 18, 2018 How on earth could you have missed it, silly boy. Dave. I assumed he was taking the p*ss! ;-) All looking good though Dave, please keep the updates and videos coming. Link to post Share on other sites More sharing options...
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