P2 Power Classification

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kylchapster
NER Y7 0-4-0T
Posts: 1
Joined: Sun Aug 21, 2016 11:37 pm

P2 Power Classification

Post by kylchapster »

Hello. I'm new to the forum and thought I would introduce myself by asking a question. Apologies if this has already been covered, but a search didn't reveal anything.

Using the BR power classification system, how would the original P2s, and by implication the new Prince of Wales, be classified? I understand that the P2s had/have a starting tractive effort which is greater than the LMS Duchess class, the BR Duke of Gloucester and the BR 9F. I know that there is much more involved in calculating the power classification than starting tractive effort, and that it is done differently for freight engines. My question is prompted mainly by wondering if Prince of Wales might qualify as a 9P.
Hatfield Shed
LNER A4 4-6-2 'Streak'
Posts: 1728
Joined: Fri Dec 23, 2011 3:34 pm

Re: P2 Power Classification

Post by Hatfield Shed »

The ratings formulae are dubious calculations based around the design ideas of folks from a lesser engineering outfit to the West, and really didn't work on Doncaster designs. (For example' the 'double count' of grate area and free gas area is a nonsense: either these aspects are correctly proportioned or they are not: and if they are, just one is required. The narrow firebox locos cannot be rated more than 6P without this fudge however; politically unacceptable.)

If it helps, my Bugatti front end P2 as running fictionally on 'my BR(ER)' shall carry 10MT on the cabside.
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