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Kermit Weeks Napier Sabre

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Kermit Weeks Napier Sabre

Old 3rd Mar 2024, 16:04
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Kermit Weeks Napier Sabre

Interesting video regarding Kermit's Napier Sabre.
The obvious question is, are those restorations using an early Napier Sabre doomed to failure?
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Old 4th Mar 2024, 07:29
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I would say 'doomed to a path with lots of challenges'. As there aren't all that many Sabres lying about, having one in your possession is a step closer to the ultimate goal and as mentioned in the video, having an early model could also be the starting point for a swap. Also, it's not impossible to get an early one running, but seeing as Kermit has two Sabres available, I can see Richard's point in selecting the later model.

Edit: I have uploaded a cutaway image here: https://www.vc10.net/div/NapierSabre_cutaway.jpg It shows a bit of the complexity of the engine. It's an impressive beast.
NapierSabre by Jelle Hieminga, on Flickr

Last edited by Jhieminga; 4th Mar 2024 at 09:55. Reason: added link to image
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Old 4th Mar 2024, 09:39
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Every time I look at the cutaway example at IWM Duxford I wonder at how the groundcrews kept them running in the field during WW2.
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Old 4th Mar 2024, 19:22
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Originally Posted by DogTailRed2
Interesting video regarding Kermit's Napier Sabre.
MiniPix UK V24 16x9 Vo1 (youtube.com)
The obvious question is, are those restorations using an early Napier Sabre doomed to failure?
My personal view is they are going to struggle, depending on who else they can find with the right credentials who may be prepared to take on rebuilding an early Sabre to flight standards. It sounded like that the guy Nick has lined up (would guess its whoever is doing the Centaurus engines for him?) turned down doing the older one for one of the Typhoon projects...?
There's not exactly a large list of sleeve valve experienced engine shops around that might be willing to do it. I remember Kermit was struggling to find any engine shop 30 odd years ago willing to take it on, back when Paul Coggan did a feature on it for Warbirds Worldwide.

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Old 4th Mar 2024, 21:48
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Originally Posted by VictorGolf
Every time I look at the cutaway example at IWM Duxford I wonder at how the groundcrews kept them running in the field during WW2.
My father was 'Q'ed on the Sabre. He said it was a beautiful piece of engineering, but a bastard to maintain. If the ignition timing wasn't 'just right', one bank of cylinders would end up 'driving' the other, with concomitant demise of the gearbox an inevitability. TBO between major servicings was 25 hrs and a plug chage was a complete pain in the tender parts. It was also a bit of an oil slinger too.....
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Old 5th Mar 2024, 08:48
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I would guess that all sleeve-valve engines are a bit oily with effectively twice as many cylinder oil films required. One between the sleeve and the block and another between the piston and sleeve.
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Old 5th Mar 2024, 09:23
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Originally Posted by DHfan
I would guess that all sleeve-valve engines are a bit oily with effectively twice as many cylinder oil films required. One between the sleeve and the block and another between the piston and sleeve.
'A bit oily' is a master of understatement DH - I 'waved in' a couple of Sea Furies over the years and the wing roots were slick with oil from the exhaust pipery (also with oil dripping out of said pipery) - looked like a total loss oil system
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Old 5th Mar 2024, 09:32
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At some point in the video Richard mentions that sleeve valve engines have a chart in their manual that shows how much oil it should consume per hour. If you're below that, you're out of oil.
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Old 5th Mar 2024, 09:50
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I remember my father showing me a manual of a sleeve valve engine after explaining the basic principles of the four stroke cycle using a Merlin engine workshop manual (which I still have over sixty years later), when I was about five or six years old. It was difficult for me to imagine how such a thing was ever designed and built. He explained that the weak spot of these engines was ensuring sufficient lubrication of the sleeve itself.
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Old 5th Mar 2024, 09:58
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ISTR that from a previous S Fury accident report - the normal oil consumption figure was 12 - 20 imp pints per hour depending on power setting.
That is a lorra lorra oil to pay for

My Austin Apache that I drove whilst working in zimbabwe was almost as bad
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Old 5th Mar 2024, 10:07
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I had a '62 Vauxhall Cresta that used nearly as much oil as petrol.

I've just remembered the first time I ever heard of a sleeve-valve engine. It was in the middle sixties and an article in Motor Sport about the original Daimler Double Six, with a Knight principle V12. Obviously paraphrasing, it's nearly sixty years ago, but it was something along the lines of: "proceeding silently along the road, followed by a cloud (or haze) of blue smoke."
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Old 5th Mar 2024, 10:25
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Originally Posted by DHfan
I had a '62 Vauxhall Cresta that used nearly as much oil as petrol.
Absolutely - my Austin Apache (which was basically an 1100 with a triumph style front end and saloon/boot) had an engine leak (cannot remember where from).
But I took 2 friends up to Harare from Thornhill AFB (about 170 miles) - pulled into petrol station in Gatooma which was approx half way - they said ''need petrol ?'' not really says I but we will need some oil .
My main use of the Apache was across town to the gliding club so the oil consumption was not normally a big deal
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Old 5th Mar 2024, 10:31
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The Centaurus prefers a particular grade of mineral oil as I recall, which is more or less unobtainable now; haven't some of the failures been attributed to other oils used instead doing damage? Think it's been discussed on here before...

Always an absolute pleasure listening to Richard talking about such matters, he is so clear in his explanations as the storehouse of knowhow in his mind pours out at a digestible rate!
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Old 5th Mar 2024, 10:51
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Yes, it's a particular grade of AeroShell, which Shell will make, but understandably there's a minimum order of about a grillion* gallons.

It seems that in theory a specified substitute is suitable, but not necessarily in practice.

*Copyright Douglas Adams.
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Old 5th Mar 2024, 12:46
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Originally Posted by treadigraph
Always an absolute pleasure listening to Richard talking about such matters, he is so clear in his explanations as the storehouse of knowhow in his mind pours out at a digestible rate!
It is but I thought he was being brave describing Kermies engine as a 1000 Hr TBO engine - I have always wondered what the highest actual TBO time a Sabre ever got to in service,I would imagine a lot less than 1000 hrs
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Old 5th Mar 2024, 12:55
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True but, as he says, Kermit would really to go some to reach 1000hrs on it, even if Richard gets the thing airborne in the next year or two. A trip up to Oshkosh and back from Polk City probably would only amass 10 to 15 hours I'd imagine.

I trust Kermit will fly the thing at a UK display or two before shipping it home. Assuming it does come here for restoration. Roll on Part 3...

Interspersed with his purchase and relocation of The Cosmic Muffin... anyone got some B-17 wings to spare? How come I didn't see that when I went on a boat tour of the Fort Lauderdale waterways 30 years ago...
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Old 5th Mar 2024, 20:22
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Originally Posted by DHfan
Yes, it's a particular grade of AeroShell, which Shell will make, but understandably there's a minimum order of about a grillion* gallons.

It seems that in theory a specified substitute is suitable, but not necessarily in practice.
Yep.
There's a rumour that the last batch of it left was sitting in one of the storage tanks that went up with the Buncefield oil terminal explosion......but I suspect there's no truth in that though.

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Old 6th Mar 2024, 08:10
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Originally Posted by longer ron
It is but I thought he was being brave describing Kermies engine as a 1000 Hr TBO engine - I have always wondered what the highest actual TBO time a Sabre ever got to in service,I would imagine a lot less than 1000 hrs
I don't know... the Sabre got a bad reputation due to the problems with the early versions. The servicability of the later versions, such as in the Tempest TT.5, was fine according to several sources (just don't ask me to list these right now...).
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Old 6th Mar 2024, 17:46
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I read something in Group Captain Desmond Scott's Typhoon Pilot about the Typhoon's Sabres being susceptible to engine rapid failure in Normandy due to ingestion of sand on the forward airstrips damaging the cylinders. Apparently an efficient air filter was designed in a matter of days to fix the problem.
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Old 6th Mar 2024, 20:21
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I`m sure I read some yrs ago on the `real` Flypast` forum that `someone had found that there were some Sabres being used as water pump engines` in S.California..Don`t recall if it was verified,as it was at the time `Flypast` changed hands.....So ,who knows....
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