Simon Thomas
Senior Airman
The Tempest had two engines available to it. If the Sabre was a "miserable failure" then surely they would have switched all to be powered by the Centaurus?
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At the time the Centaurus was itself absolutely excelling at being a failure, it was probably even further behind than the Sabre.The Tempest had two engines available to it. If the Sabre was a "miserable failure" then surely they would have switched all to be powered by the Centaurus?
I've seen figures for 3,317 Typhoons, (did you include the Mk1a, & Hawker built units) plus weren't many of those 1943 Typhoons taken backSabre, just over 5,000 built to end 1945, production continued through 1946, about another 200 built, plus there was a conversion program of II, IIA, IIB and IIC into VA
3,215 Typhoon plus 942 Tempest V and VI comes to 4,157. However the engine situation was so bad in 1943 several hundred Typhoons in storage were reduced to spares as they had little chance of ever receiving an engine. In 1945 even some Tempests were being reported as "slaved to purgatory storage", no engine fitted. Typhoons are over represented when it comes to numbers turned into Maintenance Airframes. So deduct about 10% from the aircraft figure.
The Tiffy was Pissy?
The Typhoon had a design flaw like the early Bf109F causing structural failure near the tail, in both cases the fix was simple once the problem had been understood. The main Typhoon problem was the engine performance and availability. Typhoon cumulative production was 227 by end June, 448 by...ww2aircraft.net
The Tempest V finished production in August 1945, the 142 Tempest VI (July 1945 to June 1947) used the Sabre V, about 130 V and VA had been built by end 1945.
They are manufacturing, rather than design issues, & of course, like F1 drivers, the fighter pilots wanted its performance, it was up to theThat is quite a novel approach to inferring engine reliability.
It is worth noting, that an aircraft which crashes and the airframe of which is destroyed or even just written off does not require a new engine for that airframe,
and that an aircraft which is lost over enemy terratory does not require a new engine for that airframe.
The RAF knew perfectly well what the Sabre was like and were inspecting them constantly and rebuilding them at tiny service intervals
once the sleeves started playing up to make sure they DIDNT blow all engines up. For a very long time whilst Merlin`s were
doing 200>400 hours between major overhauls, Sabre`s were being taken apart at 50/70 hours or less. None of that
requires a replacement engine for that airframe either, but is still a catastrophically bad position.
A slightly more solid viewpoint on what it was actually like is to be found if you read the Air Ministry files,
part of the reason for there not being so much effort put into rebuilding them at tiny intervals was
that there WERE no spare engines.
Even in 1943, the Air Ministry description of the Sabre was "from bad to worse" (see 4th page down)
"never likely to become a reliable engine" (see 5th page down)
"it was on balance a miserable failure" (see 6th page down)
- By the final 12months of the war it was just about there in terms of being reliable to a practical degree, but
that was far too late.
Please note I think its a fascinating engine, and it would be a good thing to get one running again now,
but - at the point in time back then, it was an immensely troublesome, difficult unreliable engine
for most of the war, these are simply recorded facts.
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Note: This is hours between FAILURES IN FLIGHT, not T.B.O.
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"Average engine life is 67 hours"
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They are manufacturing, rather than design issues, & of course, like F1 drivers, the fighter pilots wanted its performance, it was up to the
makers to sort out their end of the stick. Even the very early Typhoon, rushed into service full of bugs, showed why the Merlin was passe`
See: http://www.wwiiaircraft.org/typhoon/Typhoon_AFDU_Tactical_Trials.pdf.
Ironically, at a meeting where the RAF brass were canvassing views as to whether the Typhoon/Sabre program should be cancelled,
there were many 'boffins' spouting exactly the kind of appraisal listed in the letters shown, but one Squadron Leader present,
(later a test pilot, of some note) R. Beamont piped up, & asked if the RAF 'expert' (who was an experienced Spitfire pilot) bagging
the Typhoon so heavily - had ever flown a Typhoon? & of course, he hadn't - which 'spiked his guns' rather...
Yes, IMECHE has some useful documents, some are viewable online, now too.Sure thing you go with whatever info you feel most comfortable with, here is what I feel comfortable with >
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Of course, it was the Bristol sleeve manufacture/finishing method that was needed.
Can you post some pix of boost bent/broken sleeve valves? Or is that apocryphal?The Sabre appears to have been oversold before it really entered production (not the only example by far), manufacturing difficulties were a real problem (and not just for Napier).
A lot of drawings/prototype planes were trashed because they couldn't make enough Sabres.
The Sleeve valve lost some of it's edge when the engine designers starting figuring out what 100-130 fuel could really do.
The sleeve valve would not stand up to high boost without bending/breaking the sleeves which stopped the engine pretty quick. It got better but not anywhere near quickly enough.
An engine using 18lbs of boost can move 27% more air than one using 11lbs of boost. Actually power needed to achieve that boost and the altitudes it can be done at change things somewhat.
Hercules didn't go over 8.25lbs of boost until the 100 series.
In 1935-1940 with 87 to 100 octane fuel the sleeve valve looked like it might provide some answers. In 1940-41-42 the better fuel allowed poppet valve engines to close up some of the difference with fewer problems. But the engine and airframe programs were too far along to cancel and bedsides "the solution" was just around the corner/a few weeks or months away
If you check the differences for 1st & 2nd iterations in the Sabre VIII spec-sheets listed by Wilkinson, the later unit not only shows the upratedThe sleeve acting as an oil pump of sorts may be quite true.
Part of our problem in sorting out the sleeve valve situation is that often the reports are snapshots in time. What was true late in WW II was not true early in WW II, or what was true in the 1950s.
Oil consumption was quite problem with the early Hercules, to point of oil fouling the spark plugs, More than an annoyance in overwater flights. It was solved, but the claim that all the Sleeve valve problems were solved in 1933 or even 1938 doesn't hold up.
I don't have a good timeline for the later Hercules and Centaurus engines. The last engine types appear to have been built between 1953 and 1956 ( I don't have the 1954 and 1955 editions of Aircraft engines of the World) and the 663, and 673 (?) show up in the 1956 book but not the 1943 book. Also showing up in the 1956 book is a listing for the 373 and 873 which were intended for the Blackburn Beverly but never fitted (if indeed they were ever built?)
with around 10 years of development after WW II quoting performance specs needs to done carefully. On both sides.
They do not have "SOME useful documents" they are the custodians for the entire remaining Napier Archive material.Yes, IMEC has some useful documents, some are viewable online, now too.
They do not have "SOME useful documents" they are the custodians for the entire remaining Napier Archive material.
If that is so, is this box (MS/2056 - Sabre test reports & etc) held at the Science Museum, empty?
Records of D. Napier and Son Ltd. | Science Museum Group Collection
Comprisies calculations, diagrams and reports from the office of P.J. Wallace, Test Plant Department, mailny relating to the testing and development of Napier Sabre aero-engines and interconnected control box. Also photo album relating to Napier Research Station, Liverpool.collection.sciencemuseumgroup.org.uk
I have seen and cross referenced the production figures in British National Archives files AIR 19/524, AIR 8/278, AVIA 46/146, AVIA 10/315, AIR 20/1871, AVIA 49/229 . The Ministry of Aircraft Production (MAP) monthly Statistical Bulletin for 1942 to 1945, plus the 1945 Statistical Review. Ministry of Supply Monthly Statistical Bulletin reports from February 1946. Plus of course the published RAF serial listings, 3,317 is all Typhoon production plus the 2 prototypes P5212 and P5216I've seen figures for 3,317 Typhoons, (did you include the Mk1a, & Hawker built units) plus weren't many of those 1943 Typhoons taken back
for airframe modifications, (sliding bubble-canopy/Tempest tailplane/4-blade prop/1000lb bomb shackles)?
Yes, along with prototype Sabre which are not in the production statistics. Firebrand 9 mark I (5 from June to August 1943, 4 from May to October 1944) 12 mark II (June 1944 to February 1945) again ignoring prototypes. The mark II is reported to have used the Sabre III, of which 25 were built October 1942 to February 1944. The mark III used the Centaurus, over 2,900 produced to end November 1945There were also 20+ production Firebrands, plus numbers of prototypes/research aircraft flying with Sabre engines too, of course.
Yes, certainly, but as well as Napier archive papers/pix - the Science Museum also holds an actual Napier Sabre engine, too.Yes amazingly enough huge national scale projects have boxes in other places, Cambridge University archives are the official
holders of the Vickers Supermarine company archives, stunningly there are also copies of a few Supermarine reports about Spitfires at Kew.
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There is a scientific paper comparing sleeve versus poppet valves on the Aircraft Engine Historic Society Website. I am a member and read the document probably 10 years ago. I cannot locate it right now and I don't believe I can share it here anyways.
Yes, Raymond really ought to have revised that article by now, certainly as a 'thesis' it would not been passed by an informed supervisor,
Go and write your own paper then.Yes, Raymond really ought to have revised that article by now, certainly as a 'thesis' it would not been passed by an informed supervisor,
based on a number of cogent points.