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Old 9 March 2012, 01:03 PM   #1
Bentley Rotary
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Clerget 9J

Does anyone have any information, sources, photos or drawings of the 100hp Clerget 9J?
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Old 13 March 2012, 07:18 AM   #2
Kacey
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A Little Something

Quote:
Originally Posted by Bentley Rotary View Post
Does anyone have any information, sources, photos or drawings of the 100hp Clerget 9J?
I'am sure you are aware that there was one listed on display at:

9J - 100hp, 10.7lt, 9Ry, a, 250lb Ruston & Hornsby Works Museum: (Gwynne-built)

Don't know if it is still there?

That's all I could find.

KC
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Old 13 March 2012, 07:29 AM   #3
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Thanks KC

The only two I am aware of are at the Museum of Lincolnshire life and possibly??? in the Sopwith Baby at Yeovilton. Maybe the R&P one ended up in the museum?

Thanks for the details of power weight etc., at 10.7 litres it was a small engine to produce 100hp.

All the best,
BR
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Old 13 March 2012, 01:46 PM   #4
Bletchley
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There is a photograph and description here:

1920 | 0123 | Flight Archive

Air Board data lists a 110 hp Clerget used to power a Hamble Baby with a normal BHP of 114 at 1200 rpm at sea level (from a test report dated May 1917). Although 9J is not specified I think this must be a different 110 hp Clerget to the 9Z, as this is also listed, but with a normal BHP of 122 at 1250 rpm at sea level (in a Sopwith one and a half strutter).

Hope this helps

Bletchley
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Old 14 March 2012, 01:27 AM   #5
Bentley Rotary
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9J vs 9Z

Thanks Bletchley, useful information, isn't the Flight archive superb!

What I am trying to determine is what design input, if any, WO Bentley had to the Clerget 9J; or was the engine a later copy of the AR1/BR1, if somewhat smaller. It has lot, but not all, of the Bentley design features.

There appears to be a scarcity of information about when the 9J was designed and what it was used for. The 9Z, although a similar size and may have been the basis for the 9J, appears to be have been much more popular, even though the power to weight does not appear to have been as good, why?

Thanks again,
BR
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Old 14 March 2012, 08:18 AM   #6
Bletchley
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Hello BR, Hartmann lists the 9J as 110 ch (slightly less than 110 hp) at 1500 rpm, just 99 kg in weight, and developed in 1918 - so the Air Board reference I gave to the Hamble Baby cannot have been to a 9J. See:

http://www.hydroretro.net/etudegh/clerget.pdf

I would doubt if Bentley had any direct involvement with this, so if Gwynnes built it then I guess this would have been under a Clerget licence, long after Bentley had left.

I did a bit of digging around some time ago into the relationship between Gwynnes, Clerget and Bentley, see:

http://www.theaerodrome.com/forum/ai...-triplane.html

Hope this helps some

Bletchley

Edit: if you live in or near London, the National Archives at Kew has a number of documents relating to the Clerget engines that might be of interest to you - you can look up the titles of these documents online by going to the online catalogue and typing in 'Clerget' as the search term.

Last edited by Bletchley; 14 March 2012 at 08:23 AM.
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Old 14 March 2012, 08:54 AM   #7
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9J vs AR1

Thanks again for the information and links Bletchley, I wish my French was better!!

I initially thought that WO's involvement with the 9J was unlikely as it is suggested that one of the reasons WO wanted to leave Chiswick was that Gwynnes did not want to go as far from the Clerget licence as to have steel liners in aluminium muffs. That is until I found a tatty piece of foolscap in the WO Bentley Memorial Foundation's archive. On it has been hand written, by Nobby Clarke, in relation to breakage of the aluminium muff of the cylinders, "I have today examined three types of cylinder (1) cylinder of the old screwed head type: engines 1 to 43"

This would suggest that he was either talking about the 9J or that the design of the first AR1s was very different to the later engines. I cannot discover which is correct as I cannot find any evidence of when the 9J was first produced or that the initial AR1s were different to later engines although all I have seen about the AR1 would suggest the design was substantially the same throughout production???

Thanks again,: BR
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Old 14 March 2012, 02:05 PM   #8
Bletchley
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Have you read Graham Mottram's pamphlet "W.O. Bentley's Aero-Engines" that is published by the W.O. Bentley Memorial Foundation (Publication no.3 ISBN 9780954090128)?

Right at the end there is a section 'Bentley's First Engine', where Mottram refers to a 'Clerget' fitted to the FAA Museum's Sopwith Baby that turned out to be, very probably, an early Bentley design that may have predated the AR1: "To all external appearances the engine is a Clerget, with a split crankcase held together by clamp bolts and the usual Clerget valve gear of twin push rods. The 'bastard' cylinders however [composed of a ferrous liner (most probably cast iron), closed by a screwed-on ferrous head, and enclosed in a cast aluminium muff], follow Le Rhone practice, the bottom two inches being threaded to screw into the crankcase, with stop rings to lock them in place" (p.22)

Perhaps the first 43 engines produced by Humber were of this type?

Mottram suggests that this may have been an early version of the AR1 used for the Bristol M1C:

"There is some mystery attached to the Bristol M1C which had an Admiralty AR1 engine, in an RFC ordered machine in April 1917, and which performed poorly. Even with the 110 hp Clerget the monoplane was outstanding for its time. Why should it do so badly with 150 hp from a Bentley? If it was a true AR1 perhaps it was a poor first copy, but could it possibly have been this mystery engine? It may have produced 95 hp in good condition"

Bletchley

Last edited by Bletchley; 14 March 2012 at 02:24 PM.
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Old 14 March 2012, 02:23 PM   #9
Omega
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I have a Clerget oil pump marked 100hp but it seems to be the same pump for all Clerget types. I can send some detailed pictures if you need them.

Anyone know the difference between the 9Ba and the 9Bb and a simple 9B Clerget?

Koz

Last edited by Omega; 13 April 2012 at 01:58 PM.
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Old 14 March 2012, 02:29 PM   #10
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Clerget parts

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

Last edited by Omega; 13 April 2012 at 01:58 PM.
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