Last & Best of the Piston Engine Fighter Aircraft.

[Tommy Cookers]

... in racing usage, so 2Vs made winning power, & 4Vs had shown no
performance advantage, (US Miller/Offenhauser blown engines excepted)

... Cosworth knew ...

your friend Mr Grandprix engines has rather muddled things .... not noticing that .....
in racing usage the 4v Mercedes-Benz dominated from 1934 to 1940 (and expected 1954-5 dominance to be 4v)
also 4v Maserati 8CL eg sometimes beating the above 1938-9 - and winning twice the Indy 500
and 4v Maserati 4CL being much the best postwar 4 cylinder F1 car
and notice that the (nee Miller) Offenhauser then Meyer-Drake engine was of course unblown

yes there was a 4v famine in the 50s - but this wouldn't have happened if MB hadn't messed up their 54-55 plan
(as there was after Fiat introduced supercharging in the 20s tiny cylinder 1920s using 2 valves going beyond the bore)
but eg Tresilian patented well oversquare 4v (or 3v) engines and sold his 4v 2.5 litre F1 design to BRM (who 2v'd it)

Honda in liquid-cooled 1964/5 1500cc F1 and 1965/66 1000cc 4v engines freely chose to have a large VIA
'Honda also provided in 1965 a F2 IL4 1.0L engine for a Brabham chassis with 4v/c wide-angle head' (says primotipo)

yes of course the (air-cooled) motorcycle might be less keen on 4v
but the 1949 3 valve 350cc AJS won a WC GP or two

of course MV Agusta followed Honda to 4v and conspicuously beat them (also Benelli followed)
Jawa followed - gaining 3% power at 7% higher rpm (11400 rpm on 63mm stroke was too much)- then reverted to 2v
the Dino 156 followed similarly needing disproportionately more rpm for more power
this all looks like evidence that 2v was fine with small cylinders
the 1973 KRM Super Streak 4 cylinder 350cc racer's designer chose 2v
he was CJ 'Jack' Williams (designer of the 2v AJS 7R and its 2v 45 hp development c 1965) - father of Peter Williams)

the Cosworth SCA by 1966 got 143 hp vs the 1966 Honda RA 302e F2 150 hp (not totally unrelated 1968 RA302 F1 car)
the press at that time predicted a 3 litre F1 V12 of SCA type (the FVA/DFV being secret)

https://forums.autosport.com/topic/2116 ... otor-1966/
https://primotipo.com/tag/honda-ra302e-f2-engine/


Napier went from air-cooled aero engines with poppet valves to liquid-cooled .... they should have stopped there

[J.A.W.]

As Seeley could relate, big capacity Honda bikes of the`60s were not troubled by lack of hp,
but rather by the chassis/steering/tyre dynamics required to exploit it.

Halford's last Napier poppet valve engine had hydraulic/automatic valve clearance, but of course
once they gained the advantage of liquid cooling, they stayed with it ("stopped there") usefully,
with the Sabre, whereas R/R went back to fiddle-faddling with X-type air-cooled mills, but to no avail...

[wuzak]

Halford's last Napier poppet valve engine had hydraulic/automatic valve clearance, but of course
once they gained the advantage of liquid cooling, they stayed with it ("stopped there") usefully,
with the Sabre, whereas R/R went back to fiddle-faddling with X-type air-cooled mills, but to no avail...

You have a thing about Rolls-Royce.

Going back to "fiddle-faddling with X-type air-cooled mills" amounted to the 2750 cubic inch Pennine designed for the post-war commercial airline market. With initial testing giving ~2800hp it was promising, but Rolls-Royce dumped it in favour of working on gas turbines.

"To no avail" I assume means that the engine did not gain orders. Which is true, but it was killed before that stage.

The Napier Dagger and Rapier were, of course, failures.

The Sabre was used, almost exclusively, in the Typhoon and Tempest. They stuck with the Sabre because that is all they had.

They developed the Nomad, which was expensive and complicated. They were behind Rolls-Royce, de Havilland, Armstrong Siddeley and Bristol on gas turbines.

[J.A.W.]

Halford's last Napier poppet valve engine had hydraulic/automatic valve clearance, but of course
once they gained the advantage of liquid cooling, they stayed with it ("stopped there") usefully,
with the Sabre, whereas R/R went back to fiddle-faddling with X-type air-cooled mills, but to no avail...

You have a thing about Rolls-Royce.

Going back to "fiddle-faddling with X-type air-cooled mills" amounted to the 2750 cubic inch Pennine designed for the post-war commercial airline market. With initial testing giving ~2800hp it was promising, but Rolls-Royce dumped it in favour of working on gas turbines.

"To no avail" I assume means that the engine did not gain orders. Which is true, but it was killed before that stage.

The Napier Dagger and Rapier were, of course, failures.

The Sabre was used, almost exclusively, in the Typhoon and Tempest. They stuck with the Sabre because that is all they had.

They developed the Nomad, which was expensive and complicated. They were behind Rolls-Royce, de Havilland, Armstrong Siddeley and Bristol on gas turbines.

"A thing about R/R..." Wuzak?

That thing would be, that R/R failed with their attempts at piston aero-engines other than a
conservative (if highly developed) V12, inc' both attempts at a Sabre competitor (3, with Griffon)
& nothing coming of their attempts at sleeve valve engines, despite knowing the advantages.

That British industry built so few Sabre (& fewer yet Centaurus) engines in wartime - (not that
R/R made many Griffons, after the Vulture debacle either) of course - limited usage options.

As for (off topic) gas-turbines R/R used its business power to usurp the designs/engineers of
competing British companies post-war, (with political connivance) eventually inc' Napier & Bristol.

It is useful to delineate technical, from commercial 'failures', esp' since airframe developments
in the period 1935/45 were often outstripping engine availability, yet the post war focus on the
Meteor jet caused the opposite problem IMO, akin to putting Merlin engines in Gladiator biplanes!

[wuzak]

That thing would be, that R/R failed with their attempts at piston aero-engines other than a
conservative (if highly developed) V12, inc' both attempts at a Sabre competitor (3, with Griffon)
& nothing coming of their attempts at sleeve valve engines, despite knowing the advantages.

What attempts to build a Sabre competitor?

The Vulture? Made it to production before the Sabre. A couple of years before the Sabre. I'm sure if Rolls-Royce had the resources spent on the Sabre for the Vulture it would have become a success but, alas, they were too busy winning the war with the Merlin at the time to use that amount of time and money on the Vulture.

The Griffon? The Griffon was designed for naval aircraft, not as a rival for the Sabre. Then some bright spark realised that the Griffon could be made to fit the Spitfire, and so a redesign was performed and the Griffon Spitfire was born. A Sabre Spitfire was not possible, as the Sabre was bigger in all dimensions (L x W x H) and 20% heavier.

The Eagle 22? The closest thing to a competitor to the Sabre that Rolls-Royce made. Big and heavy, it was more powerful than the contemporary Sabre (1944) but far less sorted. I'm not sure if it was ever contemplated as a replacement/alternative to the Sabre, but was proposed for different projects. It was replaced in its one production application by a gas turbine.

The Pennine? Never was to be a competitor for the Sabre.

That British industry built so few Sabre (& fewer yet Centaurus) engines in wartime - (not that
R/R made many Griffons, after the Vulture debacle either) of course - limited usage options.

There were so few built because making them in production was a problem. In fact, Napier basically went bankrupt. The Air Ministry's preferred solution was for Rolls-Royce to take over Napier, but that was blocked.

As for (off topic) gas-turbines R/R used its business power to usurp the designs/engineers of
competing British companies post-war, (with political connivance) eventually inc' Napier & Bristol.

Napier weren't playing in the same markets for gas turbines as Rolls-Royce and Bristol.

Not sure abut the political aspect.

Napier just seemed to have died out.

Bristol merged with Armstrong Siddeley in the 1950s and then was bought by Rolls-Royce in 1966.

It is useful to delineate technical, from commercial 'failures', esp' since airframe developments
in the period 1935/45 were often outstripping engine availability, yet the post war focus on the
Meteor jet caused the opposite problem IMO, akin to putting Merlin engines in Gladiator biplanes!

There was limited money in Britain for post-war jet fighter development, which meant that the Meteor was kept on longer than it otherwise would be.

[J.A.W.]

The Vulture def' was R/R's intended Sabre competitor, yet despite extensive re-design efforts
could not be made competitive, & was culled, after R/R assured the Air Min that their Griffon
could do the job, until their own version of the Sabre was ready, but neither scheme panned out.

R/R tried hard to get both Griffon & Eagle into Hawker's Tempest, & significant effort was wasted
in doing so, getting to flying stage with the Griffon, but Eagle 22 only on paper, it being too late...

Here is a recent, typically very well done Bill Pearce piece on the doomed Vulture:

https://oldmachinepress.com/2021/01/05/ ... ft-engine/


Napier's management bungling & R/R political machinations were the reasons behind Sabre production
being so retarded, the engine itself was a sound design when built correctly, as clearly shown by
RAF fighter training schools continuing to fly them hard, up 'til the mid `50s.

Napier aero-engine manufacture was taken over by R/R, & consequently closed in haste, (per UK gov)
& their gas turbines culled due to US pressure, (along with the Fairey Rotodyne) & the replacement
in Westland built (US design) helicopters by a licence manufactured GE unit...

The Meteor was built in huge numbers (& it killed its pilots likewise) since while US/Soviet 2nd gen
swept wing jet fighters were flying in service, the British equivalents were delayed for years by
indecision over engines (& R/R's difficulty in getting their Avon to work well), so getting F-86's from
Canada to tide them over, while Australia built their own version, being tired of waiting for Hawkers!

[wuzak]

The Vulture def' was R/R's intended Sabre competitor, yet despite extensive re-design efforts
could not be made competitive, & was culled, after R/R assured the Air Min that their Griffon
could do the job, until their own version of the Sabre was ready, but neither scheme panned out.

The Vulture wasn't designed as a competitor to the Sabre, but as a 2000hp class engine, the same class the Sabre was aiming for.

The Griffon did the job - in Fireflies and Spitfires.

Rolls-Royce didn't even begin on the Eagle until 1942/43.

R/R tried hard to get both Griffon & Eagle into Hawker's Tempest, & significant effort was wasted
in doing so, getting to flying stage with the Griffon, but Eagle 22 only on paper, it being too late...

Where do you get the idea that Rolls-Royce were that keen to get the Griffon into the Hawker fighters, considering they were already selling as many as they could make?

There were paper designs for Supermarine and Hawker fighters using the Eagle 22. Neither went ahead in any form.

Here is a recent, typically very well done Bill Pearce piece on the doomed Vulture:

https://oldmachinepress.com/2021/01/05/ ... ft-engine/

Doomed is a strong word. Underdeveloped is better.

The reality is that the Vulture was cancelled because Rolls-Royce did not have the time and resources to devote to its development. It was not cancelled because it could not compete with the Sabre.

Napier's management bungling & R/R political machinations were the reasons behind Sabre production
being so retarded, the engine itself was a sound design when built correctly, as clearly shown by
RAF fighter training schools continuing to fly them hard, up 'til the mid `50s.

What "political machinations"? You keep saying stuff like that, but it sounds like a conspiracy theory.

The production system for the sleeves was a problem for Napier. It was the cause of the bulk of the Sabre's early troubles.

It required the Air Ministry to order Bristol to help and secure for Napier several grinding machines that were originally destined for Pratt & Whitney.

The Griffon was in active RAF service until the 1990s.

Napier aero-engine manufacture was taken over by R/R, & consequently closed in haste, (per UK gov)
& their gas turbines culled due to US pressure, (along with the Fairey Rotodyne) & the replacement
in Westland built (US design) helicopters by a licence manufactured GE unit...

In other words, they didn't have a competitive modern engine for sale.

The Meteor was built in huge numbers (& it killed its pilots likewise) since while US/Soviet 2nd gen
swept wing jet fighters were flying in service, the British equivalents were delayed for years by
indecision over engines (& R/R's difficulty in getting their Avon to work well), so getting F-86's from
Canada to tide them over, while Australia built their own version, being tired of waiting for Hawkers!

Australia's F-86s used Avons.

[Tommy Cookers]

the Vulture wasn't '2 Peregrines' ....
it was in cylinder pitch '2 Merlins' - and we have been told that one ran with Merlin-sized bores
an X engine can be as good as the meeting of 4 rods on 1 crankpin ie the rpm it can allow

Not exactly the same Tommy.
Bore spacings (per RRHT) for the main Rolls-Royce piston aero engines of the WW2 era:
Vulture – 6.1in
Kestrel/Peregrine – 5.625in
Merlin – 6.075in
Griffon – 6.9in
The Vulture was originally rated for 3,200rpm (Peregrine 3,000rpm) and the later Pennine, with short stroke (and Merlin bore) was rate to 3,500rpm.

Sabre cylinder bore spacings (by scaling from photo of drawing)
7.2in nominal (typical)
7.4in average (equivalent allowing for the larger pitch of the middle cylinders)
7.7in average (equivalent allowing also for conrod stagger)

NB
RETRO-EDIT - wrongly I used 5.5in cylinder bore when scaling (5in should have been used) ... so ....
CORRECTED Sabre bore spacing (with allowances as above) is 7in

the 2 poppet-valved 5.25"x4.75"separate-cylinder H24 Lycoming XH-2470 gave 2300 hp @ 3300 rpm for 2430 lb weight
the VE benefit of sleeve valves being less with smaller cylinders and strokes ....
Napier might have made a smaller and much lighter H engine by using poppet valves

[J.A.W.]

The Vulture def' was R/R's intended Sabre competitor, yet despite extensive re-design efforts
could not be made competitive, & was culled, after R/R assured the Air Min that their Griffon
could do the job, until their own version of the Sabre was ready, but neither scheme panned out.

The Vulture wasn't designed as a competitor to the Sabre, but as a 2000hp class engine, the same class the Sabre was aiming for.

The Griffon did the job - in Fireflies and Spitfires.

Rolls-Royce didn't even begin on the Eagle until 1942/43.

R/R tried hard to get both Griffon & Eagle into Hawker's Tempest, & significant effort was wasted
in doing so, getting to flying stage with the Griffon, but Eagle 22 only on paper, it being too late...

Where do you get the idea that Rolls-Royce were that keen to get the Griffon into the Hawker fighters, considering they were already selling as many as they could make?

There were paper designs for Supermarine and Hawker fighters using the Eagle 22. Neither went ahead in any form.

Here is a recent, typically very well done Bill Pearce piece on the doomed Vulture:

https://oldmachinepress.com/2021/01/05/ ... ft-engine/

Doomed is a strong word. Underdeveloped is better.

The reality is that the Vulture was cancelled because Rolls-Royce did not have the time and resources to devote to its development. It was not cancelled because it could not compete with the Sabre.

Napier's management bungling & R/R political machinations were the reasons behind Sabre production
being so retarded, the engine itself was a sound design when built correctly, as clearly shown by
RAF fighter training schools continuing to fly them hard, up 'til the mid `50s.

What "political machinations"? You keep saying stuff like that, but it sounds like a conspiracy theory.

The production system for the sleeves was a problem for Napier. It was the cause of the bulk of the Sabre's early troubles.

It required the Air Ministry to order Bristol to help and secure for Napier several grinding machines that were originally destined for Pratt & Whitney.

The Griffon was in active RAF service until the 1990s.

Napier aero-engine manufacture was taken over by R/R, & consequently closed in haste, (per UK gov)
& their gas turbines culled due to US pressure, (along with the Fairey Rotodyne) & the replacement
in Westland built (US design) helicopters by a licence manufactured GE unit...

In other words, they didn't have a competitive modern engine for sale.

The Meteor was built in huge numbers (& it killed its pilots likewise) since while US/Soviet 2nd gen
swept wing jet fighters were flying in service, the British equivalents were delayed for years by
indecision over engines (& R/R's difficulty in getting their Avon to work well), so getting F-86's from
Canada to tide them over, while Australia built their own version, being tired of waiting for Hawkers!

Australia's F-86s used Avons.

Wuzak, the Vulture was very def' seen by R/R (& the Air Min) as a Sabre competitor, (the Sabre initially
was regarded as a 'fall back' option - in the then seemingly unlikely event of mighty R/R failing),
as can be evidenced by the both Tornado/Typhoon manufacturing orders, an the 'tardy' efforts
put into organising proper Sabre production protocols.

It was shameful that Bristol had to be coerced into assisting Napier in wartime (esp' since
Bristol wasn't offering the Centaurus in competition, focus being on their Hercules, for
non high-performance air-superiority fighters).

It is my understanding that the oft-noted 'Sundstrand grinders' were 'compensation' for
cancellation of the proposed deal for Chrysler to renege on Sabre production in USA, &
get the big Wright radial production/reliability sorted for the super-priority B-29 program..


Signally no such 'HMG Whitehall' pressure was put on R/R, indeed Napier/E.E was ordered to
deliver a recent mark Sabre to Derby, in order to facilitate advancement of R/R's H24 clone..

The Vulture suffered the fate of all X-crank aero-engines, & being a 'cobbled together' design,
(& despite being constantly revised) was deemed a dud by Hives, (he was happy to sell 4 Merlins to
replace 2 unreliable/underperforming/reputation-ruining Vultures in Britain's very profligate/costly
heavy-bomber gambit) - & it always amazes me that given such large scale 'export to Germany'
programs by expensive/rare metal scrap, that Todt/Speer didn't insist on use of recycled items
in German engine manufacture, for example even the poppet valves from Allied engines ought to
have been repurposed, surely, let alone piston & bearing alloys...

Of course Hives had to give undertakings to Beaverbrook/Air Min, that while the Vulture was a dodo
in 1942, R/R could 'out Sabre the Sabre', & even so, substitute the Griffon, in the meantime,
& they wanted the Sabre cancelled as a 'quid pro quo' - a fact which is on the historical record.

Should you care to check, R/R was notorious for 'dirty dealing' - from Bentley through Rover/Whittle
to the 1960's final takeovers of the remaining British aero-engine makers - & backed by UK gov.

The Griffon went to the FAA, & fitted to the Spitfire (in fairly small numbers) did (sort of) 'keep it
in the game' (while the Merlin really 'did the biz' in Lancaster/Mosquito/Mustang), but didn't power
the RN's Sea Fury' let alone any RAF Tempests. It never matched the Sabre for its tasks, even when
optimised for low-level use, & throttled back oceanic droning in Shack's didn't compare with drogue
dragging at realistic speeds for fast-jet interception training duties, obviously...

About helicopter turbines, the record shows that the British Gov, being heavily indebted (to USA),
& wanting to receive similar cold war defence largesse as was going to fellow Euro-Nato members
- was fully prepared to 'sell down the river' its own aero-industries ('cept R/R of course, they got a
plum contract to ruin F-4 Phantoms by bulging them around their Spey turbofans - in a poorly
executed attempt to emulate what the Australians had done with the Avon in the F-86 - while
Hawker still dithered, then accepted a contract for the Harrier, & cancellation of a Mach 2 fighter).

[J.A.W.]

the Vulture wasn't '2 Peregrines' ....
it was in cylinder pitch '2 Merlins' - and we have been told that one ran with Merlin-sized bores
an X engine can be as good as the meeting of 4 rods on 1 crankpin ie the rpm it can allow

Not exactly the same Tommy.
Bore spacings (per RRHT) for the main Rolls-Royce piston aero engines of the WW2 era:
Vulture – 6.1in
Kestrel/Peregrine – 5.625in
Merlin – 6.075in
Griffon – 6.9in
The Vulture was originally rated for 3,200rpm (Peregrine 3,000rpm) and the later Pennine, with short stroke (and Merlin bore) was rate to 3,500rpm.

Sabre cylinder bore spacings (by scaling from photo of drawing)
7.2in nominal (typical)
7.4in average (equivalent allowing for the larger pitch of the middle cylinders)
7.7in average (equivalent allowing also for conrod stagger)

the 2 poppet-valved 5.25"x4.75"separate-cylinder H24 Lycoming XH-2470 gave 2300 hp @ 3300 rpm for 2430 lb weight
the VE benefit of sleeve valves being less with smaller cylinders and strokes ....
Napier might have made a smaller and much lighter H engine by using poppet valves

No T-C, re-check that final Sabre VII BMEP figure, some serious volumetrics there on 100-130/+20lbs boost, while being strong enough to hack full throttle at sea level required some 'meat on the bones',
plus that Lycoming surely never made those figures as a production rating, nor flew with that output.

Likewise, the Vulture couldn't cope with those rpm in service & was successively de-rated,
even if R/R attempted to add boost to substitute for cutting allowable rpm - it, along with
all manner of mechanical modifications (except the most fundamental) - was all in vain..

Pennine never flew, AFAIR, & R/R wasted effort trying to 'civilise' their hard-running hi-po Merlin
as a potential airline mill, but failed even against British rival Bristol - with their more efficient
(& quieter, non flame-spewing) Hercules - let alone the vast numbers of US radials practically
glutting/dumped on the market, post-war (not that poor/broke Brits could afford them, either).

[Tommy Cookers]

Not exactly the same Tommy.
Bore spacings (per RRHT) for the main Rolls-Royce piston aero engines of the WW2 era:
Vulture – 6.1in
Kestrel/Peregrine – 5.625in
Merlin – 6.075in
Griffon – 6.9in
The Vulture was originally rated for 3,200rpm (Peregrine 3,000rpm) and the later Pennine, with short stroke (and Merlin bore) was rate to 3,500rpm.

Sabre cylinder bore spacings (by scaling from photo of drawing)
7.2in nominal (typical)
7.4in average (equivalent allowing for the larger pitch of the middle cylinders)
7.7in average (equivalent allowing also for conrod stagger)

the 2 poppet-valved 5.25"x4.75"separate-cylinder H24 Lycoming XH-2470 gave 2300 hp @ 3300 rpm for 2430 lb weight
the VE benefit of sleeve valves being less with smaller cylinders and strokes ....
Napier might have made a smaller and much lighter H engine by using poppet valves

... Sabre VII BMEP figure, some serious volumetrics there on 100-130/+20lbs boost, while being strong enough to hack full throttle at sea level required some 'meat on the bones',
plus that Lycoming surely never made those figures as a production rating, nor flew with that output.
Likewise, the Vulture couldn't cope with those rpm in service & was successively de-rated....

according to the IMechE Ricardo's paper said in 1927 wte ....
'conventional design won't allow more than 1500 hp - so greater VE is necessary ie the sleeve valve'
Heron's similar USAAC 'Hyper' work said (relatively) small individual cylinders allowing high coolant temp were needed

both apparently saw as inescapable and permanent .....
low quality fuel and uncooled valves and separate cylinders and inefficient supercharging ..... and ....
both were wrong on all counts

the (separate-cylinder) H24 Lycoming being 11% lighter than the (smaller displacement) Sabre shows that .....
a poppet-valved 'monobloc'-cylindered H24 should have been a winner (setting aside the Vulture sorting)


the Typhoon and the Tempest were 7 ton fighter aircraft doing the job of 4 ton fighter aircraft .... because ....
the Sabre (pointlessly for the fighter job) bought high power at the price of such high weight
(the Fury tried to escape this - 'cheating' the British fighter norms by having a smaller wing - a different argument)
remember any Sabre intended for higher altitudes would have weighed over 3000 lb

[J.A.W.]

Frank Halford & Harry Ricardo had a fair bit of 4V poppet valve/H-24 engine design/building
experience between them, & given the Sabre 'made the cut' for useful wartime duty, when
neither Vulture nor the Heron-concept Lycoming did, your 2nd guessing T-C seems ah, 'brave'..

As for your weights & measures T-C: "7 ton.." No, nowhere near, but as Wilkinson's tome notes, the
late Sabre handily bested the contemporary Griffon in hp/lb ratio, with the Tempest Mk I powered by
Sabre IV (which was ~150lb heavier than the Sabre II, & not "3000lb") made ~470 mph @ 24,500 ft,
& of course Camm had the Tempest constructed up to a ~14G ultimate stress rating,
a reserve rather more robust than the 'dainty' Spit...

Addit: The (non-navalised) Hawker Fury wing was pretty much the Tempest wing, but butted together
beneath the full stressed skin/monocoque fuselage, rather than mounted outboard on a spaceframe.

[wuzak]

Frank Halford & Harry Ricardo had a fair bit of 4V poppet valve/H-24 engine design/building
experience between them, & given the Sabre 'made the cut' for useful wartime duty, when
neither Vulture nor the Heron-concept Lycoming did, your 2nd guessing T-C seems ah, 'brave'..

Depends on what you mean by "useful".

The Vulture was operational in the Manchester in 1940 - 1942. Reliability was poor, but not all due to the engines. Operating the Manchester exposed the problems and enabled the fixes, which meant that most of the issues had been dealt with when the Lancaster came into production.

Does that qualify as useful?

Frank Halford' own H-24 was a poppet valve engine which also did not do any useful wartime service. Its capacity limited its usefulness - the Napier Dagger.

Not sure what Harry Ricardo has to do with anything. By WW2 he was pushing the 2 stroke sleeve valve engine, which was the Rolls-Royce Crecy. That also did not do useful service. Did no service at all, in fact, and never flew.

[J.A.W.]

Frank Halford & Harry Ricardo had a fair bit of 4V poppet valve/H-24 engine design/building
experience between them, & given the Sabre 'made the cut' for useful wartime duty, when
neither Vulture nor the Heron-concept Lycoming did, your 2nd guessing T-C seems ah, 'brave'..

Depends on what you mean by "useful".

The Vulture was operational in the Manchester in 1940 - 1942. Reliability was poor, but not all due to the engines. Operating the Manchester exposed the problems and enabled the fixes, which meant that most of the issues had been dealt with when the Lancaster came into production.

Does that qualify as useful?

Frank Halford' own H-24 was a poppet valve engine which also did not do any useful wartime service. Its capacity limited its usefulness - the Napier Dagger.

Not sure what Harry Ricardo has to do with anything. By WW2 he was pushing the 2 stroke sleeve valve engine, which was the Rolls-Royce Crecy. That also did not do useful service. Did no service at all, in fact, and never flew.

I was replying to T-C's suggestion that a larger, liquid-cooled Dagger, rather than the Sabre as built,
would've proven to be a better aero-engine, & that such an option, (though doubtless given due
consideration by Halford et al), somehow 'missed the boat' of improved 100+ avgas, which was pending.

I suppose the Vulture was 'useful' to the Germans, as an object lesson demonstrating why X-24 engines
were 'problematic beyond promise', (& sadly) by causing more 'wastage' to the RAF, than to themselves.

The Crecy was one of several R/R sleeve valve engines (& at least a couple of them did fly), which
never amounted to anything useful, other than to meet Hives' obligations to Air Min directives, &/or
absorb funding/resources which perhaps may've been more useful to R/R's competitors...

[wuzak]

I was replying to T-C's suggestion that a larger, liquid-cooled Dagger, rather than the Sabre as built,
would've proven to be a better aero-engine, & that such an option, (though doubtless given due
consideration by Halford et al), somehow 'missed the boat' of improved 100+ avgas, which was pending.

I don't know if it would have been a better engine. That is hard to quantify.

But it would be cheaper and easier to make.

I suppose the Vulture was 'useful' to the Germans, as an object lesson demonstrating why X-24 engines
were 'problematic beyond promise', (& sadly) by causing more 'wastage' to the RAF, than to themselves.

The Germans had the Daimler Benz DB 604, which did not go into production.

It was slightly larger than the Vulture at 46.3L/2830ci (vs 42.5L/2592ci), about the same weight and rated at 2,500hp.

I have not found a reason why it was abandoned.

The latest design improvements for the Vulture were not implemented before it was cancelled.

And remember that the Merlin had its fair share of development issues. But the Merlin had a 2 or 3 year head start on the Vulture.

The Crecy was one of several R/R sleeve valve engines (& at least a couple of them did fly), which
never amounted to anything useful, other than to meet Hives' obligations to Air Min directives, &/or
absorb funding/resources which perhaps may've been more useful to R/R's competitors...

The first Rolls-Royce sleeve valve engines were the Kestrels converted by Ricardo to become the RR/D (Diesel) and later RR/P. The RR/D failed because the bottom end was not designed for Diesel cylinder pressures. Neither were flight units, since they used a gang of spur gears mounted on either side of the crankcase to drive the sleeves.

The Exe, which did fly, was rather too small in capacity for it to have a long term future. It did fly and was quite reliable (despite being an X-24).

The Pennine followed large radial practice (like R-2800) in having a single piece master rod and built up crank. Only one was built and it never flew.

The Eagle 22, which did fly and went into production for a short time. It still needed more development.

Hives wanted to cancel development of the Crecy so he could concentrate on the Merlin and Griffon. Funding may have come from the government, but the resources were Rolls-Royce's and Hives allocated the minimum amount he could get away with.

Your comment makes it seem like Rolls-Royce were taking possible funding away from their competitors. But it was funding for a program Rolls-Royce did not want to do. It may have been that a certain amount of funding was sent to each manufacturer for development of their engines. It would explain why Rolls-Royce wanted rid of the Crecy (and Exe, Peregrine and Vulture) - they would have more to spend on the Merlin and Griffon. If it was additional funding just for the Crecy then Rolls-Royce would have likely not desired to kill the program.