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Aircraft Topics related to WWI aircraft, aircraft engines and armament

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Old 15 March 2012, 08:33 AM   #11 (permalink)
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Bristol M1B

Thanks Bletchley, I was aware of Graham's monograph but he does not identify the engine or its origin. I believe the Yeovilton Baby's engine does not have a manufacturers plate although it does have the features of the Clerget 9J. Unfortunately the earliest AR1 to survive that I know of is Humber No. 117 which is in Canada. I would be extremely interested to find evidence/pictures of earlier AR1 engines.

I have just read up on the Bristol Monoplane and, as you suggest, it did not perform as expected with the AR1 engine in. Bruce gives the test report as M87, do you know whether such a report will still exist somewhere and if the engine number was recorded in such documents? Unfortunately with the spinners that were used on the M1 details of the engine cannot be seen.

Omega,
I am afraid I do not know the differences between the 9Ba abnd 9Bb and cannot find any reference to them. The Clerget oil pump design was used on the Bentley engines including AR1, BR1 and early BR2 engines and I would be very interested in any detailed pictures.

All the best,
BR
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Old 15 March 2012, 08:54 AM   #12 (permalink)
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Quote:
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Two different styles of Clerget Central mounts. Not sure if one was used on the 100hp type. Both of these were from Clt 9Ba and a 9Bb.

Koz
Hello Koz,

Do you have a Clt 9Ba and or 9Bb? Or diagrams/blueprints?

KC
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Old 15 March 2012, 01:02 PM   #13 (permalink)
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Quote:
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Hello Koz,

Do you have a Clt 9Ba and or 9Bb? Or diagrams/blueprints?

KC
KC,

I have a Clerget 9Ba. I have compared it to a 9B and a 9Bb and they appear to be the same engine. Any thoughts? The central mount or valve springs may be part of the designation but I am not an expert. I have never seen any reference for the suffix on the Clt 9B.

Koz

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Old 15 March 2012, 01:33 PM   #14 (permalink)
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BR, I have not seen M87 in full but Air Board data sheets give performance data from this flight test (March 1917) - identified as a 150 hp AR1:

Normal BHP and RPM at sea level: 150 at 1250
Speed in MPH at 6,500 ft: 115.5; at 10,000 ft: 110; at 15,000 ft: 100
Time (in mins) and rate of climb (in ft per min): 6,500 ft 5.8/830; 10,000 ft 11.1/525; 15,000 ft 27.7/150
Ceiling: 17,000 ft

No engine number though

Bletchley
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Old 15 March 2012, 02:35 PM   #15 (permalink)
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Quote:
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KC,

I have a Clerget 9Ba. I have compared it to a 9B and a 9Bb and they appear to be the same engine. Any thoughts? The central mount or valve springs may be part of the designation but I am not an expert. I have never seen any reference for the suffix on the Clt 9B.

Koz

I also have NO information on what a 9Bb would be. However, based on all the sources I have in my library I believe the 9B was the original design with cast iron pistons and the 9Ba upgraded to aluminum piston with same compression ratio and gained 5cv (i.e. 130 increased to 135cv).

Have you measured the compression ratio of your 9Ba? Are the pistons alumimum? Are they the same concavity as the original 9B?

This may be to much to be asking for, but then again maybe not.

I have a guess as to what a 9Bb might be, but I need more information first.

Respectfully,

KC
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Old 25 March 2012, 04:09 AM   #16 (permalink)
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Attached are some pictures of a Clerget oil pump and tach drive. The drive is marked 100hp so possibly a 9J. I think it was common to all Clergets. You may also be correct about my 9Ba as it has aluminum pistons, see attached. Please let me know if you need any other details.

Koz





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Old 25 March 2012, 02:45 PM   #17 (permalink)
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KC,

I have not measured the compression ratio of the Clerget but it has concave aluminum pistons. I have no prints or drawings for the Clerget engines but I have a copy of the manual produced for H.M. Air Services and it is invaluable!

Thank you for the note, please let me know if you figure out the a vs b engines.

Sincerely,

Koz

Last edited by Omega; 13 April 2012 at 01:58 PM.
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Old 27 March 2012, 10:48 PM   #18 (permalink)
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RNAS Aero Engine Book

Good Morning All,

Sorry about the delay in writing but I have had a new source to review. I have been lent two volumes of the RNAS 'Aero Engine Data Book' dated 1918 (see attachment). Although small format the engineering drawings and photographs included suggest the design of the AR1 did not go through any major changes and thus only engine with aluminium cylinders, screw on heads and cylinders was the Clerget 9J.

Unfortunately the 9J is not included in the book but if only 43 were produced it would hardly be considered a 'principal aero engine'. I am resonably convinced now that WO must have achieved more when at Gwynnes than usually acknowledged but would like some proof such as the production dates of the 9J and what aircraft it was used in.

Does anyone have any idea of records which may be useful?

All the best,
BR
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Old 28 March 2012, 11:35 PM   #19 (permalink)
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Sounds very interesting, BR - you are thinking that the Clerget 9J may have been a later collaboration between Gwynnes and Clerget et Blin arising from the single cylinder experimental engine that Bentley is said to have produced for Gwynnes?

Let us know if you find out anything more

I guess you will already have looked at all the Clerget-related records from this period in the National Archives?

Bletchley
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Old 28 March 2012, 11:51 PM   #20 (permalink)
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Bentley, Gwynnes & Clerget

Bletchley,

I have not looked at the records for Gwynnes/Clerget at Kew yet, I have been chasing Humber and Daimler records in Coventry!

I think you have crystallised the question well, was the 9J a later effort of Gwynnes? were Clerget involved in some way (I have found no reference in French texts to the 9J) or was the engine the brain child of WO while he was at Chiswick?

I will keep on searching,

All the best,
BR
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