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By: 9th April 2012 at 22:18 Permalink - Edited 1st January 1970 at 01:00
-I think that is the case. Bristol aero-engines carry two numbers; one from the manufacturer and another from the Air Ministry.
By: 9th April 2012 at 22:41 Permalink - Edited 1st January 1970 at 01:00
-The best person to clarify the numbers on Merlin's is to speak to Ian at RR Heritage .They have a full listing of every Merlin built and what it was first fitted to he should be able to tell you what is what as they are extremely helpfull.
Mike E
By: 9th April 2012 at 22:53 Permalink - Edited 1st January 1970 at 01:00
-Where did you locate the two numbers; on the engine or in the aircraft’s paperwork?
I once tried to confirm that part of a Bristol Hercules engine I had was definitely from a particular aircraft but the ‘loss card’ for the aircraft only listed the Air Ministry number (five digits, starting with a one, no letter prefix) and not the engine number I had (possibly) found stamped on the engine part.
By: 9th April 2012 at 23:08 Permalink - Edited 1st January 1970 at 01:00
-Sorry, our posts overlapped a bit there I think.
Unfortunately I didn’t have the engine plate for my Hercules part; just an engine number stamped on a casting, but the number on the AM Form 78 was the Air Ministry number (similar in format to one of your numbers) not the (prefixed) Bristol one. Not conclusive I know...
...better wait until a Merlin expert lets us know! :o
By: 9th April 2012 at 23:28 Permalink - Edited 1st January 1970 at 01:00
-"A" numbers are recorded on engines built by all manufacturers, I've certainly always taken it to be a sequentially allocated number issued by the Air Ministry because of that cross manufacturer use. Sometimes both numbers are recorded on 1180s but more often than not it is one or the other number.
By: 9th April 2012 at 23:58 Permalink - Edited 1st January 1970 at 01:00
-I don’t remember an ‘A’ prefix on the numbers on the AM Form 78 I had but I could be wrong; definitely not a Bristol engine number though.
By: 10th April 2012 at 05:28 Permalink - Edited 1st January 1970 at 01:00
-Andy.
The A prefix is the Air Ministry contract number, the other is the Rolls-Royce engine numer, which is always an odd number on right-hand rotation Merlins. Both numbers are unique to that particular engine.
Pete
By: 10th April 2012 at 08:26 Permalink - Edited 1st January 1970 at 01:00
-The A-number is unique to the engine and was used across the board, so Hercules engines as mentioned would also have a unique A-prefixed contract number.
On paper, the engines were built in batches to Air Ministry contracts which had another number, for example, Merlin III, No 19407 / A144641 was one of a batch of 600 built to contract No 974105/38 (1938), and also an order No 4950, which I think is a Rolls-Royce order number. The only way all these numbers relate is on paper. I don`t know if there is any logic to the AM number stamped on the engine, they appear to have been issued roughly serially, earlier engines have a lower number.
People do sometimes quote the AM number as the "engine number", which is often done on Air Ministry records, but with Merlin engines, the true engine number is agreed to be the Rolls-Royce one.
Pete
By: 10th April 2012 at 10:42 Permalink - Edited 1st January 1970 at 01:00
-The A-number is unique to the engine and was used across the board, so Hercules engines as mentioned would also have a unique A-prefixed contract number.
I don't suppose there is an existing central register that cross-references all these numbers is there?
By: 10th April 2012 at 12:01 Permalink - Edited 1st January 1970 at 01:00
-I don't suppose there is an existing central register that cross-references all these numbers is there?
Not really, just information that is with Hendon and the PRO at Kew. That`s as far as I am aware anyway.
I think the Rolls-Royce heritage Trust at Bristol may keep production records for the Hercules.
It`s also not usually possible to say which aircraft serial number a particular engine was fitted to, again because there is no database to cross-reference with.
Pete
By: 10th April 2012 at 22:05 Permalink - Edited 1st January 1970 at 01:00
-Would either of the Rolls-Royce Merlin engine numbers have been marked anywhere else on the engine apart from the engine plate; individual engine components or castings for example?
By: 10th April 2012 at 22:24 Permalink - Edited 1st January 1970 at 01:00
-Would either of the Rolls-Royce Merlin engine numbers have been marked anywhere else on the engine apart from the engine plate; individual engine components or castings for example?
Yes, both numbers appear on the plate and the port front mounting foot, the Rolls-Royce engine number usually appears in many places. There are exceptions to this, but it's nearly always the case.
The sectioned Merlin Peter Vallance has at Gatwick doesn't appear to have any recognisable numbers.
Pete
By: 10th April 2012 at 22:34 Permalink - Edited 1st January 1970 at 01:00
-The Hercules seems to have the Bristol engine number stamped on most of the major engine components including the cylinder-barrels and the cylinder-junkheads; pity I haven’t been able to cross-reference that with the Air Ministry number.
By: 3rd August 2023 at 14:42 Permalink
-My boss has a merlin block that has been made into the mother of all coffee tables and bears the serial number 307101. Just wondering if anybody could shed any light on it's history.
By: 3rd August 2023 at 16:53 Permalink - Edited 3rd August 2023 at 17:51
-Hi Booomer.
I have a copy of the Air Ministry list of engine numbers and looked up the details recorded for “307101”. According to the official list you have part of a Bristol Hercules VI, one of the 3,000 ordered under contract B. 33820/39.
However, had it been 317101 …
By: 3rd August 2023 at 17:00 Permalink - Edited 3rd August 2023 at 17:50
-Anonymous (if you’re still here). “For example, P9374 had a Merlin III numbered 13769 but it also had an A-prefixed number which was 143668.”
[AM] 143668, a Merlin III, one of 200 built to contract 819222/38.
By: Anonymous (not verified) - 9th April 2012 at 20:49
Perhaps this is one for Merlin Pete?
Can anyone clarify why the two engine numbers on RR Merlins?
For example, P9374 had a Merlin III numbered 13769 but it also had an A-prefixed number which was 143668.
I have always thought the second number was an RAF or Air Min number (hence "A"?) but would welcome some clarification.
Which was the official engine number - or was one the RR number and 't other an RAF number??