Channel 4 model railway challenge

[Hobby]

Battery Electric locos, that's certainly a niche taste, Pete, good for you!  

Edited January 29, 2018 by Hobby

[Guest]

Battery Electric locos, that's certainly a niche taste, Pete, good for you!  

 

I'm having a mid-life crisis. I no longer feel the need to conform...

[Coryton]

I know of one and it's certainly not new.

Because there was nowhere on the loco to put it, Hornby's live steam Rocket has its gas tank in the tender connected to the burner by a flexible tube. Admittedly it is within the legal requirements for toy live steam not requiring a boiler certificate (which I believe is a boiler pressure of no more than one bar)  The Rocket's original gas tank was a nightmare as it used the same cigarette lighter nozzle for filling as for delivery and the O ring had a nasty habit of being frozen by any escaping gas so ensuring that all the gas would escape.

 

 

1 bar above atmosphere?

 

 

I've often thought that if certain American rocket engineers had ever owned one of these things the crew of the space shuttle Challenger might have been spared. (It was the great and always inquisitive physicist Richard Feynman who discovered that the true cause of the disaster was a frozen O ring. His comments are worthwhile reading for anyone engaged with safety critical systems https://science.ksc.nasa.gov/shuttle/missions/51-l/docs/rogers-commission/Appendix-F.txt.    

 

Off topic, but...

 

He has a slightly different version of this in one of his books, namely that it wasn't his observation - some people in NASA had known of this but didn't dare publicly comment. He was given a hint so that he could be the one to make the "discovery".

[Captain Kernow]

I thought this episode was fab, too.

[Jeff Smith]

So, currently visiting the UK and watched last night's episode. I was not impressed but have now read the back story, ie, this thread.... I have a feeling that like The Great British Baking Show, this will make it's way across the Pond and probably appear on US Public Television. I saw James May's exploits some years ago.

 

I have a very dim view of pre-recorded so called reality shows as I know from an acquaintance who edits such shows in Hollywood, that editing can tell whatever story the director requires....nevertheless I am amazed that the loco performed so well even though being apparently massaged through much of the route....

 

Well done to all those that had the patience and desire to get involved and be assured that my views are not aimed at you..... Personally I am not convinced that this is good for the hobby but if sales of live steam/large scale get a boost all well and good!

[Hobby]

in Hollywood, that editing can tell whatever story the director requires.

 

I got the impression that was standard practice for anything coming from Hollywood, especially movies "based on fact"...

[Jeff Smith]

Absolutely, even names can be changed in conversations to completely alter the sense of a comment or conversation!

[NittenDormer]

I happened to notice a trailer for 'Undateables' during one of the advert breaks.

[lochlongside]

I enjoyed this episode ........

 

One problem is where do we go from here? What is the next challenge?

 

In the area near the Swanage Railway perhaps we could have a temporary live steam railway along some of the disused narrow gauge clay tramways that are currently used as footpaths or bring back steam in miniature along parts of the Somerset and Dorset Railway or the Yarmouth to Freshwater Railway.

I too enjoyed Ep 4 - I particularly liked the pragmatic  " .....real life solution or model railway solution......" at the 20 min point  - it is bit invidious to pick out one team especially as Media Camera teams can actually lie like a cheap s/h watch !!  but I will (!!) and I have got to say Claire and her team are ticking all the right technical and team participant/leadership boxes  - and this is the team that built the trestle bridge as well - so that is two spectacular constructions both done collaboratively and without fuss. However one does have to sympathise with the pbi (poor b****y infantry) slogging along the tracks and roads laying miles of track in proximity to heavy lorries for actually quite minimal TV coverage except when things go wrong.

 

Where to go next is a v good qn  - I have got a feeling this could be a one-off unfortunately as a follow-on would have to present the same sort of length and terrain challenge as the Scottish Highlands but still associated with the UK to be marketable to a Ch 4 domestic non-railway audience, many of whom would associate with the geographical area (e.g. hols)  rather than Model Railways; This was sufficiently so much more of a step up in challenge terms compared with James May's Barnstaple attempt that I am not sure Swanage would be sufficiently difficult to be a followup The problem is finding a UK location of an acceptable length to be obviously challenging whilst also being sufficiently unbuilt upon to be practical.

 

- The S&D with the Mendips could be an interesting option - especially thro Blandford  - the station(built over), the town centre viaduct (blown up - you can imagine Strawbridge having some fun there as an ex R Signals officer who trained at Blandford),  and finally the River Stour (bridge removed) - I think unfortunately it might be a non-starter however as much of the route has probably been developed or sold off into private ownership.

- S&C - there is a vacant track space over RibbleHead viaduct and plenty of potential background history - trouble is there is a railway already there to ease the way , or more likely get in the way (although given the number of Network Rail personnel involved they wouldnt have to worry about trespass!!)

- Southern withered arm - could be interesting but don't know it well enough but it is probably less populated than the alternatives.

 - GCR London extension - probably too much of a long shot even if there are some photogenic bits like the preserved railways along its length as there has been a lot of non-picturesque development along its length.

 

Perhaps the railway history buffs among us could come up with another "might-have been" line? In the meanwhile i must try to work out how to buy and fit a Roundhouse loco into my currently overextended loco spend profile and my pitifully small suburban garden !! This must be doing wonders for their sales !!

[Jeff Smith]

I think it would be a mistake to do another similar series unless it was sufficiently different in concept, ie teams competing against each other rather than against the environment. For example you could have say four teams having to construct bridges from drinking straws across identical model valleys and carrying out stress tests as per historical practice using identical weight locomotives/trains. etc, etc. This might stimulate young minds to get interested in engineering. Of course it would have to have it's share of personnel disagreement, failures and drama to keep a wider audience interested but it could be filmed in a controlled environment to reduce story leaks.....

[Mallard60022]

I think it might be fun to do a few programmes about railways like the RH& DR and the Ratty. Bit of history, bit of local interest and plenty of action in 30 minue episodes. Loads of people have no idea there are such little lines other than (say) the Snowdon or Welshpool style that get a load of exposure in holiday style info. 

Phil 

[34theletterbetweenB&D]

I think it would be a mistake to do another similar series unless it was sufficiently different in concept, ie teams competing against each other rather than against the environment. For example you could have say four teams having to construct bridges from drinking straws across identical model valleys and carrying out stress tests as per historical practice using identical weight locomotives/trains....

 That last word is the missing element in the current programme. What is being demonstrated is that the Victorian railway engineers made the right decision: because the railway it is proving possible to construct is one which doesn't allow a train of any sort to be pulled, let alone one with a commercial payload.

 

So, hire one of the Cardington hangars, create three or four series of identical landscape obstacles down the length of it in a moderately resistant material as 'courses', give the teams identical not over generous resources including track, traction, rolling stock, materials, tools, and the first team to lay a railway and move say 10,000 scale tons of pea shingle from one end to the other by train operation alone wins. In O gauge that would be 150 kg and the wagon capacity might be scaled to require 25 complete trainloads. Undercover with artificial light they can work three shifts, 24/7 to help contain costs. 

[Pacific231G]

1 bar above atmosphere?

 

Errr, yes. an engine using steam at atmospheric pressure wouldn't provide much power (possibly an atmospheric engine?) but I'm not sure if that is the lmit. I did read somewhere that Mamod live steam toy could go up to 3bar (2bar above atmosphere)

[Suzie]

My Mamod engine has a quoted pressure of 25psi which I guess is where the safety valve is set. I make that a little over 1.7bar

[Colin_McLeod]

Surely quoted pressures are all above atmosphere.

[lochlongside]

I think it would be a mistake to do another similar series unless it was sufficiently different in concept, ie teams competing against each other rather than against the environment. For example you could have say four teams having to construct bridges from drinking straws across identical model valleys and carrying out stress tests as per historical practice using identical weight locomotives/trains. etc, etc. This might stimulate young minds to get interested in engineering. Of course it would have to have it's share of personnel disagreement, failures and drama to keep a wider audience interested but it could be filmed in a controlled environment to reduce story leaks.....

 Think you might be right - but on another point - Mr Attenborough and the green brigade will be after you with a vengeance - drinking straws indeed  - ..... how could you - you guys at the back have just got to keep up !!!

[Mallard60022]

 Think you might be right - but on another point - Mr Attenborough and the green brigade will be after you with a vengeance - drinking straws indeed  - ..... how could you - you guys at the back have just got to keep up !!!

Fear not, paper straws dear heart. They can then be recycled or made into a thousand pipe loads for all those lovely plastic kit built Pipe Wagons that we all so love.

N. V. Ironment

[34theletterbetweenB&D]

Errr, yes. an engine using steam at atmospheric pressure wouldn't provide much power (possibly an atmospheric engine?) ...

 That was the atmospheric engine, generally attributed to Newcomen. The steam was generated in a boiler at barely above atmospheric pressure, just enough to exclude the air. The power stroke occurred when the steam was condensed to create a partial vacuum in the cylinder, by atmospheric pressure acting on the open piston face; thus 'atmospheric engine'. Very poor power to weight ratio, insufficient to be of much utility in moving a vehicle. That had to wait for 'strong steam' where the pressure of the steam was well above atmospheric pressure, and the steam drove the piston against atmospheric pressure.

[Pacific231G]

 That was the atmospheric engine, generally attributed to Newcomen. The steam was generated in a boiler at barely above atmospheric pressure, just enough to exclude the air. The power stroke occurred when the steam was condensed to create a partial vacuum in the cylinder, by atmospheric pressure acting on the open piston face; thus 'atmospheric engine'. Very poor power to weight ratio, insufficient to be of much utility in moving a vehicle. That had to wait for 'strong steam' where the pressure of the steam was well above atmospheric pressure, and the steam drove the piston against atmospheric pressure.

Indeed. The inefficiency wasn't such a problem when Newcomen engines were being used to pump out coal mines (except that some of the otherwise saleable coal was used) James Watt improved efficiency considerably by introducing a separater condenser but his engines still used steam only slightly above atmospheric pressure.

It seems to have been Murdoch who first demonstrated the use of high pressure steam (several atmspheres) but Trevithick, then a mine engineer, who developed it. first for stationary beam engines to avoid paying royalties for Boulton and Watt's separate condenser but soon for smaller "puffing" (discharging exhaust steam to atmosphere) steam engines that could be used in vehicles but were mainly used as portable engines for running machinery such as stamps. These engines were smaller and had a far better power to weight ratio than an "architectural" beam engine but weren't more efficient as they didn't use the expansive properties of high pressure steam. 

 

Trevithick brough both principles together at Wheal Prosper in 1812 with what became the Cornish engine. Cornwall's metal mines had to import coal for their pumping engines at great expense from S. Wales so there was a great incentive to using it more efficiently. This engine used steam at higher pressures and, more importantly for efficiency, allowed it to expand in the cylinder. It was still though acting against a partial vacuum as the exhaust steam from the previous stroke was drawn into the separate condenser*.

 

Steam locomotives discharge their exhaust steam into the atmosphere (and are consequently very inefficient) but most other steam plant has always remained partally atmospheric. After the live steam has passed through usually three compound cylinders or nowadays turbines it ends up in a separate condenser kept to as high a vacuum as possible.

 

The legal and propaganda battle between Bouton and Watt, who championed essentially atmospheric engines, and Trevithick and others who believed in the new fangled "strong" steam seems to have parallels to that between Edison (DC) and Westinghouse (AC) over electrical systems.

 

*There are a good number of preserved Cornish engines around but I believe the largest working example is the 90inch engine at the London Museum of Water & Steam near Kew Bridge in Brentford. They also have the world's largest surviving beam engine but the 100 inch isn't currently working.

Edited January 31, 2018 by Pacific231G

[34theletterbetweenB&D]

...The legal and propaganda battle between Boulton and Watt, who championed essentially atmospheric engines, and Trevithick and others who believed in the new fangled "strong" steam seems to have parallels to that between Edison (DC) and Westinghouse (AC) over electrical systems...

Credit where due though, they didn't descend to the level of Edison promoting human electrocution equipment using the opponents AC system in order to demonstrate its lethality, as opposed to his 'safer' DC system.

[Pacific231G]

Credit where due though, they didn't descend to the level of Edison promoting human electrocution equipment using the opponents AC system in order to demonstrate its lethality, as opposed to his 'safer' DC system.

Agreed, Learning that put me off Mr. Edison for good. Boulton & Watt did though seize on any boiler explosion as evidence of the perfidy of Trevithick's high pressure and some of their more desperate arguments make for quite amusing reading. In response to the actual dangers I hadn't realised that Trevithick invented both the safety valve and the fusible plug as well as developing hydraulic testing for boilers.

Edited January 31, 2018 by Pacific231G

[PatB]

Surely quoted pressures are all above atmosphere.

 

Pressures can be legitimately quoted as either absolute or  above atmospheric (referred to as "gauge") but aren't terribly meaningful unless it's stated which. However, common  (non-technical, for  want of a better term) usage tends to favour gauge, so unless otherwise stated or obvious from context, that's my own default assumption.

[PatB]

Agreed, Learning that put me off Mr. Edison for good. Boulton & Watt did though seize on any boiler explosion as evidence of the perfidy of Trevithick's high pressure and some of their more desperate arguments make for quite amusing reading. In response to the actual dangers I hadn't realised that Trevithick invented both the safety valve and the fusible plug as well as developing hydraulic testing for boilers.

 

I remember being rather horrified when I read about the Savery Engine, which was more or less contemporaneous with Newcomen but used far, far higher pressures to pump water. The thought of Queen Anne era metallurgy in such an application is really quite shuddersome .

[rockershovel]

Pressures can be legitimately quoted as either absolute or  above atmospheric (referred to as "gauge") but aren't terribly meaningful unless it's stated which. However, common  (non-technical, for  want of a better term) usage tends to favour gauge, so unless otherwise stated or obvious from context, that's my own default assumption.

“Pressure” as commonly used, is a misnomer for “pressure differential”, ie “gauge” pressure. However the differential is always relative to “ambient” - an example would be the cabin pressure in an aircraft, where the differential is between the defined ambient pressure at the specified altitude, and the absolute pressure inside the cabin

[Pacific231G]

Pressures can be legitimately quoted as either absolute or  above atmospheric (referred to as "gauge") but aren't terribly meaningful unless it's stated which. However, common  (non-technical, for  want of a better term) usage tends to favour gauge, so unless otherwise stated or obvious from context, that's my own default assumption.

Before I went to University, instead of doing A levels I trained  as a ship's engineer. Though I worked on one steam turbine and several diesel powered ships I never, except perhaps at college, heard pressures defined in this way. So, even in a technical context, gauge pressure was the assumed default. Somebody can probably confirm or put  me right on this but since I think it indicated zero pressure when the ship was not in steam, I assume the vacuum gauge for the condenser (in those days expressed as inches of mercury) was also relative to ambient air pressure rather than to a theoretical absolute vacuum.

 

“Pressure” as commonly used, is a misnomer for “pressure differential”, ie “gauge” pressure. However the differential is always relative to “ambient” - an example would be the cabin pressure in an aircraft, where the differential is between the defined ambient pressure at the specified altitude, and the absolute pressure inside the cabin

That varies a bit. Altimeters (which are really somewhat sophisticated barometers) are set in millibars  hectopascals which would be zero in a theoretical vacuum though they're actually set against theoretical¹  or real datums generally sea level (QNH) or the height of an aerodrome (QFE)

 

The other instruments based on air pressure are using differential pressures; the Air Speed Indicator (ASI) the difference between the pressure in a tube facing forward (the pitot) and the static pressure of the air around the aircraft² and the Vertical Speed Indicator (VSI)  the difference between the ambient pressure now and a moment earlier to give the rate of change expressed in feet per minute up or down.

 

¹Above a certain altitude you set the altimeter to a "standard" pressure setting of 1013.25 Hp which may be quite different from the actual current pressure at sea level. At lower altitudes there are other complications such as "regonal pressure setting" which,to ensure terrain separation, is the lowest forecast QNH in a region  even though the QNH at a particular aerodrome witihn the region may be higher.

 

² The Indicated Air Speed given by the ASI may be very different from an aircraft's actual speed through the air particularly at higher altitudes but it is really measuring the number of air molecules whizzing past the aircraft. It is that which gives lift to the wings, and pushes air into the engines and also gives various maximum speeds so is what you need to know to fly safely. For navigation it needs to be corrected and of course air speed is very different from ground speed.

Edited February 1, 2018 by Pacific231G