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Stewart 13:41, 5 March 2007
More intelligent RSS
I'm planning a move to MediaWiki sometime - probably later this year. I think that has the feature you request provided vandalism is removed in the right way. Watch this space... --Peter Harrison (talk) 15:23, 13 May 2009 (UTC)
Hi Ed - I was looking for a common baseline on all locomotives and so I used the 85% figure. I have not seen any linkage between this formula and superheat. It is starting tractive effort and hence superheat has no effect? I drew the formula from my ancient book by W.A.Tuplin, but it is quoted elsewhere on the net in the same way.
Our superheat is little more than steam drying , but is there another definitive source of formula I should use or talk to Wol?
Many thanks for the information on the Oil Store which is very useful. It is also good to know that there are people out there seeing what I am doing and commenting. This is what we intended to happen.
I have edited the article using your info but could do with any photos that show the building as it would have been before the roof was replaced. Do you have anything that you can email to me - firstname.lastname@example.org? Regards,
Hi Ed I'm not sure where your 80% boiler pressure figure comes from? The GWR in cataloguing the FR in 1923 used 85% across the board for all the engines, hence that was the figure used in Little Giants to give a level playing field, unlike Boyd who seemed to use 75% because of some idea of valve setting?
In practice our superheating is very weak, no more than drying, so why make a difference between superheated and unsuperheated?
The 80% is a slightly arbitrary figure, taken from this calculator.
I recall that David Lloyd George and Taliesin III have four superheating flues against the two in other locos and the Garratts have eight. Are there any figures for the steam temperatures around an FR loco I wonder? Saturated steam at 160psi will be at 185°C and any increase in temperature will improve loco performance.
The smaller diameter steam pipes and long runs in a Fairlie will also count against it, as most of the work on the derivation of the TE calculation will be on much larger locos.
What sort of max cut off do FR locos run at, as the calculator above suggests that will ave an effect too.
Looking at that website you are getting mixed up with tractive effort on the move, not starting tractive effort.
Temperature and superheat are irrelevant with starting tractive effort, so they should all be one figure (in my view 85%!)
But starting tractive effort is only a small part of the performance of a loco. If you look at K1, it is possible to make it have an amazing starting TE as you can get the LP steam chest up to the full boiler pressure, but it could never maintain that for more than a few feet from it's starting point. Similarly I've been on Prince when we've started away from Port with an 8 carr train and it went fine across the cob, but we'd have never made it to Blaenau (we swapped back to the Lady that we should have had at the Lodge)
Yes Ed, but the convention for quoting tractive effort figures is that it is starting tractive effort - nothing else, then you get a level playing field
My point is that starting TE is not a level playing field and not really a useful indicator of loco performance. K1 can come out with an amazing starting TE, but can't haul as many carriages to Rhydd Ddu as an NGG16. To take it to extremes there's the GER Decapod.
But the convention in all books is that you do!
We are, I think, going to have to agree to disagree, but would like to propose a new unit that is based on the power required to remove the skin from a rice pudding, which I think is about as relevant.
My final comment would be that the manufacturers data sheet for the C2 loco that the lads are restoring at the Lodge, gives the TE at 60% BP (about 7000lbs) rather than 85% (about 10000lbs).
and it says The purple line is the nominal tractive effort quoted on the C2 specification sheet. This appears to have been calculated from the traditional equation, using an efficiency factor of 0.6, and gives a value typical of the loco performance at a range of speeds. In the UK, an efficiency factor of 0.85 was more commonly used: this would give a value of 4574kgf which is close to the maximum tractive effort that a C2 could achieve when starting on a dry rail.QED!
Arrgghh Hoisted by my own petard! I probably should stick to reading books about loco's, rather than spending time editing wiki's. It's the internet, so everyone has an opinion!