'Increasing the Charge' - how piston engine technology provided the power to fly

JFC Fuller said:
Great, in which case there will be a paper trail somewhere, strange that the Napier Heritage Trust has no record of it and Setright appears to be the only author to have discovered this though.

The Sabre was a great engine, arguably the best design to see service in WW2 from some perspectives. However, the hero worship, and corresponding emotional conspiracy theories about why so few (comparatively speaking) were made, borders on TSR-2 levels of absurdity. The reality is that Napier didn't have the technology to manufacture the engine (it needed Bristol tech), it couldn't make a high altitude configuration and EE ultimately had to be brought in to provide proper management. Even then, it wasn't until 1945 that production and maintenance converged to end the engine supply problems.
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Indeed, the emotive outpourings, from excoriatingly condemnatory to hagiographic - per the Sabre,
are likely worthy of some kind of psycho-sociological thesis in themselves..

However, given the arcane, if not outright Dickensian, state of affairs in the British aero-engine scene,
both at Napier-Acton & the A.M./M.A.P. it is without doubt, a fabulous achievement that the Sabre,
(alone of the much hyped 'Hyper'-type mills) - actually did something practicable at all..

The missing official Napier works Sabre dyno-data, if/when located - will be icing on the 'piece of cake'.

The Do 335 is far more mythical than the Tempest/Fury, since the former did not actually get to do anything..
..in LW or post-war Allied hands, - other than some hasty & furtive test flights..

P. Clostermann writes a good read, but his story about a Do 335/Tempest encounter must be,
ah, tempered, by the fact that the RAF 2nd TAF Tempests did - in fact - bag every kind of operational
Nazi 'long-nose' prop & turbo-jet type to be had..

& Does anyone know how to access the guncam footage of such encounters..
.. Clostermann claimed to have taken some of the Do 335, & it would have been of interest..

Further, Clostermann admits he only "toyed" with 'going through the gate' - in pursuit of the Dornier,
- whereas he does describe actually doing so later, (albeit - in a new Rotol propeller equipped Tempest)
as..

" The effect was extraordinary & immediate.
The aircraft literally bounded forward with a roar like a furnace under pressure...
...I simultaneously caught up my quarry, & left my pursuers standing."
 
Interesting that the 'Pilots Notes' for the Tempest V ( early Sabre IIA powered variant) allow for
the Sabre's output at a "1 hour limit" of the "climbing power" setting at "+7lbs boost @ 3,700rpm"..

This power setting (@ 190 gph) would expend the internal fuel capacity of the Tempest (160gal),
- in less than an hour..
 
& early unreliability notwithstanding (cause of ~20% of Typhoon losses in 1st year of service) the Sabre powered
Typhoon did provide the RAF with a 4 cannon, 400+mph Vmax & 525mph Vne interceptor that could catch & destroy the FW 190 JABOs attacking Britain - & of course it was also capable of effectively delivering a fair bit of offensive external ordnance - in the fighter-bomber role.

It took a redesign of the wing & addition of a late series Griffon for the 20 series Spitfires to carry the 4 cannon fit & be cleared for a 525mph Vne, as standard - years later than the Typhoon..
 
J.A.W. said:
& early unreliability notwithstanding (cause of ~20% of Typhoon losses in 1st year of service) the Sabre powered
Typhoon did provide the RAF with a 4 cannon, 400+mph Vmax & 525mph Vne interceptor that could catch & destroy the FW 190 JABOs attacking Britain - & of course it was also capable of effectively delivering a fair bit of offensive external ordnance - in the fighter-bomber role.

It took a redesign of the wing & addition of a late series Griffon for the 20 series Spitfires to carry the 4 cannon fit & be cleared for a 525mph Vne, as standard - years later than the Typhoon..
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Absolutely, just a shame about that fat wing (solved by the Tempest) and the Sabres poor altitude performance.
 
Yeah, too bad Hives didn't send Stanley Hooker down to sort out the Sabre supercharging..(as if!).

The Tempest I/Sabre IV had unrealised wartime potential - back in `43..

From Mason's 'The British Fighter Since 1912',

"When Bill Humble carried out the initial performance checks with HM 599... he recorded a maximum
speed of 460 mph TAS at 24,000ft & , after fitting a thinner tailplane, this was increased to 472mph..."

Mind you, Mason reports the later Sabres could get things fairly moving even in the denser air below 20k ft.

Per Tempest F6..

"The original Tempest V prototype, HM 595, was modified to Mk VI standard & 1st flown
by Humble in this form on 9 May 1944...
Performance trials at Boscombe Down revealed a maximum speed of 462mph at 19,800ft..."
 
'Aircraft Engines of the World'..
.. gives (Tempest F6 equipped) Sabre 5A - take-off rating as 2,565hp/3850rpm @ +15lbs boost.

AFAIR, the increased boost settings of +17.25/+20lbs were accorded to the Sabre 7 - with ADI..
 
Sabre IV consistently failed it's type tests (three times IIRC) which is why the Tempest I orders were converted to Tempest VI orders.
 
JFC Fuller said:
Sabre IV consistently failed it's type tests (three times IIRC) which is why the Tempest I orders were converted to Tempest VI orders.
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JFCF,
-Do you know what the mechanical failure point of the Sabre IV on type-test was?
Could it have been due to high altitude supercharger set-up?

Or was this a pretext - for stopping development of a high altitude capable Sabre?

Mason writes..

"The first production Tempest V, JN 729, was flown by Humble on 21 June 1943 ( by which time
the prototype had been flown with a Sabre IV with chin radiator & had achieved a speed of 459mph
at 24,900 feet, fully loaded)."
 
According to Mason,
- the cancelled order for 400 Tempest I was replaced by orders for Tempest V, with production delays
due to the change from radiator fitment in wing leading edge to fuel tank instead.

The Tempest VI production order of 300 was reduced to 142 - as built, by the end of the war/need.

Mason also remarks re the Centaurus powered Mk II;

"This proposal had been made by Camm's staff as a result of experience being gained in 1942 with the
Centaurus Tornado, rather than for any liking of radial engines in fighters by the great designer himself..."
 
R. Beamont flew the Tempest as both Hawker test pilot & RAF combat wing leader.

& he appears to concur with S. Camm, in not really liking the Centaurus powered Tempest Mk II,
(From - 'Test Pilot')

"...the large radial cowling restricted the view...caused a noticeable reduction in directional damping
in all flight conditions...its handling was never up to the crisp, taut directional standard of the Mk V."
 
Air Ministry didn't get the memo, they ordered 2,130 in total- I have never seen final order numbers for the Tempest V but Tempest II orders certainly exceed, a substantial number, the production of Sabre Tempests.

Sabre VIII, 25lb boost for 3,350hp.
 
Which would also mean that Mk II cancellations would also exceed the number of Sabre Tempests built.

JFCF, have you a reference link for a Sabre 8 running the +25lb boost/3,350hp rating?

Was it a bomber ( Warwick) installation without an effective high speed ram intake?
 
Centaurus Tempest cancellations were because of the end of the war and no reflection on the Tempest II as an aircraft.

3,350 hp Sabre VIII (E.122) is from "By Precision into Power" by Alan Vessey. Based on this Flight page: https://www.flightglobal.com/pdfarchive/view/1946/1946%20-%201443.html

It seems like it was a fighter installation though I would caution that the same flight article also mentions 3,500hp and in another article from many years later mentions 4,000hp but also states it was intended for the Fury- though I have seen other reference anywhere to such an installation.

The Napier Heritage Trust states that the Sabre never got over 3,500 hp before breaking up and that Setrights numbers are incorrect.
 
Thanks for that JFCF, I note that the Sabres were a bit much for the poor ol' Warwick..
Power enough to push Vmax to Vne limits, & exhaust thrust to blast & burn the fabric off too..

Obviously the war's end/major aircraft cancellations included Tempests, Centaurus & Sabre alike,
but were sufficient Centaurus engines even available in 1945?

~1500 Centaurus engined Hawker Tempest/Fury were eventually built, but that was over a number of years..

I recall reading that Neville Duke, when Hawker works test pilot post war - regarded flying the most highly developed Sabre in VP 207, the 2nd Sabre Fury, as offering a fairly thrilling ride for a piston job..

A real pity it wasn't kept for posterity, along with the MB 5 & even a Spiteful/Hornet too.

Perhaps Kermit Weeks would be best to flight test his Sabres in a Fury airframe before risking the very rare Tempest V he has ( he's had it undergoing slow rebuild to flight status for a couple of decades) straight off.

Given that 'Aircraft Engines of the World' quotes specific figures for Sabre 7 ratings at various power settings
& altitudes, ( & including 3,500hp @ +20lbs for take-off), I would take that as more credible than some hearsay type of anecdote, sans evidence..

I also note that the Napier adverts in 'Flight' state - "3,000hp plus" - for the Sabre..
 
In the absence of evidence to the contrary Setirights figures should be taken with extreme caution simply due to the complete lack of consistency they have with any other published figures not to mention their outright dismissal by the Chairman of the Napier Heritage Trust, hardly hearsay. 3,000+ is classic marketing, the number was 3,050hp.

Centaurus production was ramping up rapidly late in the war with both the underground Coresham factory and the Accrington factory being turned over in large part to the type; Centaurus orders were made on the basis of Tempest II orders.
 
How many Centaurus engines were available prior to war's end?

Not enough for a combat unit to use..
Certainly the Mk II prototypes ran a fair few iterations on test..

& since the 'Aircraft Engines of the World' figures for Sabre 7 outputs at +17.25lb boost are kosher,
being confirmed by the 'Flight' article - by what valid reason do you doubt the 3,500hp @+20lbs boost
outputs listed?

Has the 'chairman' interviewed the Napier test engineers? Or seen the test data?
Len Setright stated he had, is his ( or Bill Sweetman's) credibility that questionable?

& "3,000hp plus" - could well include 3,750hp..

Certainly the test data if/when found - will speak for itself..
 
Indeed, the 3,750hp figure for the Sabre on bench test noted by Setright & Sweetman is easily feasible,
-given the posted Sabre 7 in-flight rating of 3,500hp, & the bench test figure of 3,800hp for the P&W R-2800..
& - on probability I'd be more likely to dismiss the prognostications of the 'chairman'..

Note that the competitively current Reno race Merlins are also making around that power too..

So it would appear that even Len Setright's claim for the Sabre to have produced 5,000+hp..

..at equivalent boost levels.. as are run by the racing Merlins at Reno..

.. to be well within the bounds of mechanical probability..

Step up that rich enthusiast.. & what's that 'Virgin' chap R. Branson.. doing these days..
 
Sweetman's figures came from Setright- see post 158. Setright is the only source to offer such high figures and they are directly contradicted by the NPHT. I actually don't doubt 3,500hp figure but I suspect thats where the engine tore itself apart not he bench, it seems telling to me that the Napier hypothetical 500hp fighter was only given as having 3,350hp.

The 5,000hp figures claimed by Setright are, according to my notes, based 45lb boost which seems absurdly high. Even the notorious Merlin RM.17.SM was only taken up to 36lb max and spent most of its tests at 30lbs.

I can not see 4,050rpm in any of the links you have provided, could you point me in the right direction? The Flight Sabre VII article of November 1945 gives a maximum output of 3,050hp at just over 2,000 ft with 3,850 rpm and that seems consistent across the flight archive.

In 1945 Centarus production was rapidly ramping up and orders for both Tempest IIs and the required engines were in place.
 
Centaurus production was very late.
For an engine that was apparently running in 1938 to miss WW2..

Sweetman -himself- wrote post#158?
If so, I guess it follows that he accepted Setright as accurately presenting the factory data..

As repeated several times, the 'chairman' is plainly wrong, since the specialist book 'A-E-o-t-W'
clearly lists the factory figures for Sabre 7 flight ratings, inc' 3,500hp for take off @ +20lbs boost..

The 4050rpm Sabre dive allowance is listed in the Flight article (p.552) data tables for Sabre 7 @ +17.25lbs..

Boost levels in engine dyno-room test cells are effectively unlimited, except by the mechanical strength of the
machinery.. & it would be self evident that Napier would have no shortage of expendable test engines.

The Reno race Merlins do indeed - run those boost/power levels in flight, albeit they have had decades of
racing development & run Allison con-rods ( notorious R-R design weak point) to hack it..

Given the known power output progression at increasing boost levels, there is no reason to doubt that
the Sabre could not do likewise - in proportion - to demonstrate exactly what Setright wrote..
 
I learnt long ago that specialist does not mean correct. I still think a Sabre made 3,500hp but I suspect the chairman of the NPHT is right that it probably broke up about there- the strengthening required to take it up to 45lb boost would have been very substantial indeed (there had already been strengthening to produce the VII) and Napier's own wonder fighter paper designs were accredited only with 3,350hp.

The biggest problem with the Centaurus seems to have been the Hercules being in its way.
 
& the Hercules certainly took some time to reach its development potential in production form too..
Centaurus being more complicated & heavier,with its valve gear drives mounted fore & aft of crankshaft.

As for how expressions of vague plans/mooted ideas (sans direct references) in 'Flight' articles,
- or the unverified pontifications of a 'chairman'..

.. compare to extant published detailed data sets (& obviously factory sourced figures)..

- in either 'Flight', or in a dedicated reference book 'A-E-o-t-W'..
..well, it is quite plain which holds water validity-wise..

& in the current absence of a running/flying/development Sabre..

..the 'holy grail' of course, will continue to be the 'missing/lost' Napier factory Sabre data sets.

Len Setright wrote 'Power to Fly' over 40 years ago,& stated having direct access..

.. are there any Napier Engineers with 'hands on' experimental Sabre experience still living?

& If so - then why hasn't the 'chairman' put their 1st hand recollections - on record?
 
Both AEotW and the NPHT are secondary sources, neither has a particular validity advantage. Setrights claims are quite fantastical given the era.

I would say that Hercules didn't reach its potential until post war.
 
Well, in the absence of actual Napier & Sons/E.E. letterhead factory data sheets/charts..

Seriously though, the data listed in 'Flight' - where they feature the Napier works must be fairly straight..
..since they were obviously provided with it, by N/EE for the article..

& 'A-E-o-f-t-W' clearly lists identical data, but goes further, development-wise,- since it is of a later date,
- so to any reasonable thinking chap must be the best available data set, & certainly better than hearsay..

What some may consider 'fantastical' - Len Setright wasn't actually known for outright bullshitting, was he?

In fact extrapolation of in-flight performance tests done at Boscombe Down as were based on the same airframes/altitudes - ought to be a fairly reliable way of gleaning power outputs..

Sabre Tempest sea-level performance rose from 376mph @ +7lbs boost - to 418mph @ +17.25lbs boost..
 
Napier Heritage Trust

www.npht.org

Has extensive archives, but a lot of it is unsorted and waiting for volunteers to catalogue.
 
Len Setright stated that he had obtained the figures in 'Power to Fly' from source, "...Napier R&D"
If he has been shown to be prone to use 'inaccurate' data, or worse - run stuff he just made up,
- does anyone have actual examples?

Otherwise, & given the evidence from material provided so far, there is the Sabre - flight rated @ 3,500hp..
As well as "easily capable" of significantly more on ground test, just as the R-2800 was dyno tested at 3,800hp,
- 1,000hp more than it was rated for flight..
 
Nobody is accusing of Setright of making anything up.
 
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Here, a fairly scathing U.S. report on Kawasaki's attempts to licence build a decent DB 601/5 series mill..

http://www.wwiiaircraftperformance.org/japen/ATIG-Report-39.pdf

Goes to show - producing efficaciously functional aero-engines aint generally amenable to easy outcomes..
 
To return briefly to the Turbo-blown Typhoon, and to the high altitude Kestrel also discussed earlier, I am left wondering what happened to all the RAE turbo work? Bristols used GEC units for the small number of high altitude Hercules they built, as does the Typhoon proposal. Only RR seems to have developed credible high altitude piston engines for use during the war. RAE work seems to have stopped about 1927 when James Ellor left for RR- perhaps that explains the turbo Kestrel? Did UK manufacturers ever attempt their own turbos, or was their a policy decision?
 
JFCF,
I have been slowly putting the pieces of the supercharger story jigsaw together; all the turbo experience the UK seems to have had is sad whilst the mechanically driven work at RR is more positive plus aircraft policy and Meredith's work made the mechanical a better short-term bet than the turbo;
the turbo work at RAE did not stop butlater some of it began to look suspiciously like a gas turbine! There were three Air Min sponsored paths.. Frazer and Chalmers, Brown-Boveri and in-house; Bristol kept a watching brief on F&C, Rolls on B-B, and RAE on all of them. Much more to be said when documents are read rather than scanned!
One thing that puzzled me was where Napier's got their supercharger expertise from when they moved on from turbos designed for the Lion by RAE and did their own designs for the Schneider engines. These were designed by Penn who came from the RAE and I think was in the team originally under J. Ellor.
There is a precedent for believing that Setright's figures couId reflect a run on the test bed and that is the reverse case of the Griffon I out of the 'R' engine. We know that the 'R' passed a one-hour type test for the 1931 races and then a derated version known as the Griffon I was built, probably at around 1500 hp. about a thousand down on the short-life version. All we need to do is find the document!! So far the first files I have searched at Kew do not throw any light on the matter... there are other files to be looked at on another trip!.
 
The British seemed justifiably unconvinced re turbo use, esp' for fighters,
- where the power compensation at altitude did not give enough advantage over the costly bulk & complexity..

Fighters like-wise gained most from high speed exhaust jet-thrust, to which the turbo could not offer a like push.

However, it does seem that some kind of 'arrangement' was done whereby high altitude interception/recce
would be handled by R-R Merlin/Griffon in Mosquitos/Spitfires & low altitude/ground attack would be the
job of the big Hawkers powered by Centaurus/Sabre..

Certainly there was irony in the expensive high altitude specified turbo'd P-38 & P-47 being ousted from
escort of turbo-powered B-17 & B-24 bombers by the Merlin Mustang, & relegated to low level roles..
 
This link, though in German - gives interesting photo/diagram illustrations of the ADI (C3 & MW-50) & grouped exhaust thrust arrangements as employed on the BMW radial powered FW 190..

http://www.deutscheluftwaffe.de/archiv/Dokumente/ABC/m/Motoren/BMW/Leistungssteigerung/BMW%20801%20D%20Leistungssteigerung.html
 
& from a mid `30s 'Flight' article - a French Farman 2-stage supercharger schematic..

http://www.flightglobal.com/pdfarchive/view/1935/1935%20-%201022.html
 
Rolls- tried to design a two-speed supercharger drive in the same overall engine dimensions as the single-stage drive; they had major reliability problems and so with a war coming took a Farman licence... this made the engine 6" longer and though the Hurricane could take the forward CofG move the Spitfire could not so a major tear up was schemed (Spitfire III). Priorities in the air led to the Hurricane II with Merlin two-speed single-stage s'charger and the interim Spitfire V which had the Merlin 45- the central inlet supercharger of the XX but no two-speed drive so with the cabureter mounted around the other way round had same length as the existing Spifire engine.. low altitude, etc were accommodated in the short term by a larger impeller (for high up) and cropped (foe low altitudes). RR Hucknall did the first Spitfire V conversions whilst Supermarine geared up for mass production. The flexible structure I mentioned today when talking Sabre is seen in action here. Incidently the Farman supercharger was awful aerodynamically and there was talk of RR help in exchange for the licence but the war soon put paid to that idea... and Turbomeca were doing good things anyway.
 
T, didn't R-R propose French production of a metric Merlin?

Easier mooted than done, & the effort the Russians put into French designs likewise..
 
The French government were in process of negotiating a licence for the Merlin when they were over-run. French Ford company (Fordair in Bordeaux) were to be involved. Negotiations were under way in 1939 but dragged on due to Fordair's lack of concentration. Whether they would have gone as far as metrication I am doubtful as UK would be looking for components for UK engines. Willis and Buxton from RR went and spent time at Fordair and came to the conclusion they did not know how to initiate a project (e.g. building an engine as the Americans had set up things for them to operate rather than teach them to do it themselves). A Dewoitine 520 flew with a Merlin which improved its performance but Germans arrived and that line of dev was cut-off... see elsewhere in forum.
 
Thanks for that T,

& from 'Flight' - an article featuring the R-R H-24 Eagle, - this page shows the supercharger layout..

http://www.flightglobal.com/pdfarchive/view/1947/1947%20-%200629.html
 
I suspect ol' Frank Halford would've had a wry grin when reading that R-R Eagle Flight article..

Not only no mention of near plagiarism... but then..

Looking at both crankshafts counter rotating with output through a single spur gear..
- & the horror of simultaneous firing.. no wonder the lump was both over-weight & a harmonics nightmare..

Sabre runs its crankshafts in single rotation, but phased 180`apart for firing & geared together via an "elegant"
- per L.J.K.S. - balanced compound output drive..

Like-wise in the Sabre the various drives that were subject to harmonic & shock loadings such as valve gear/ignition, were protected by the give of torsion shaft/sleeves..

The good Major H likely grinned again when seeing that R-R had also resorted to the crankshaft counterweight dampers he'd applied to his hoary old D-H Gypsy mills.. ..Sabre proved so well balanced they even deleted its needless crankshaft counterweights in its later iterations..
 
This 'Flight' article on the Hercules includes Roy Fedden's list of advantageous sleeve-valve attributes..

http://www.flightglobal.com/pdfarchive/view/1941/1941%20-%202830.html
 
I had remarked on the thirst of the P&W R-2800 (275 gal/hr) when running high power settings..

But the R-R Eagle 22 has it beat there.. it could get through 350 gal/hr!
 
I would have thought sfc was a better comparator than gal/hr?
 

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