Problems with British wartime high power piston engines

[J.A.W.]

R-R did do well in WW2 with conservative V12 designs - intensively developed - by an excellent team.

By contrast, R-R did not do so well with their 24 cylinder engines, & gave up on amazing stuff like Crecy..


Here is a current DOHC conversion - built to overcome the propensity for R-R valve gear to 'dissolve'
under the brutally high stress rigours of racing.

http://www.cottamengineering.com.au/tractor_pulling.html

 

[J.A.W.]

This 'Flight' page has a data table pertaining to Hawker Sabre-Fury performance & a bit on Bristol & R-R SFC..

http://www.flightglobal.com/pdfarchive/view/1946/1946%20-%202181.html

 

[tartle]

see also this page 279

 

[J.A.W.]

Published specifications for Napier Sabre, inc' Mk 7 with 3,500hp take-off rating ( on +20lbs boost).

http://www.wwiiaircraftperformance.org/Aircraft_Engines_of_the_World_Napier_Sabre.pdf

 

[J.A.W.]

& for those who think the Sabre was too complex..

Check out this example of mechanical monstrosity for comparative complexity.

http://www.weakforcepress.com/TornadoWP800.jpg

 

[LowObservable]

The BRM V-16 of fighter engines. Eek!

 

[tartle]

Whilst at Kew I came across these Exe RE1SM performance curves.

 

[J.A.W.]

The Exe appears to be R-R's riposte to Halford's Napier Dagger?

Bigger in displacement - but still too small to make enough power for ever larger airframes..

& air-cooling large inlines seems a developmental dead-end, given the valuable increases in fuel performance
which allowed significant supercharging/boost/power development, all of which demanded more cooling..

Radials naturally allow more space for increasing cooling fin areas than closely grouped inline cylinder banks do.

Autocratic, authoritarian, sure, but IMO - Hives was correct in deciding to drop this one..

 

[LowObservable]

Or a judgment that the FAA's glycophobia was not sufficient reason for a whole new engine program?

 

[JFC Fuller]

As far as I am aware the Exe was only ever specified for one programme (S.24/37- ultimately the Fairey Barracuda) although I seem to remember seeing somewhere that it may have been intended for Fairey FC.1 in place of the Taurus. Certainly it seems to have been in the output region that was most common for "commercial" airliners at the time.

Somewhere in Kew there is an RAE file looking at different cowling types for it.

 

[J.A.W.]

Or a judgment that the FAA's glycophobia was not sufficient reason for a whole new engine program?

Or perhaps Hives was being pragmatic about R-R's apparent predilection for problematic X layouts?
& buoyed up by Merlin progress - decided that if a Merlin still wasn't enough then a Merlinised
R/Buzzard-Griffon would be..

 

[J.A.W.]

One of the oddest things in relation to the subject question was, IMO..

How Bristol could be compelled 'kicking & screaming' under protest to share its hard won sleeve-tech with
Napier, yet neither Bristol, nor Napier got to share in, or utilize R-R's splendid - Hooker initiated- supercharger
advances..

In the US - P&W produced independent types of 2-stage supercharging for its R-2800..
..mechanical for USN, & turbo for USAAF,
& Tartle has shown us a proposed scheme for a turbo-Typhoon, - but it came to naught..

Bristol & Napier never got 2-stage superchargers into service..

Strange, really.

 

[tartle]

There is a difference between a war-time imperative to keep the Typhoon going and performance improvements on Bristol's engines. RR did not have something magic to hide from the others ... the Merlin superchargers were the result of hard work by a large number of departments at Derby. Maybe Bristol had starved its engine department of resources because of the money spent by Fedden on the sleeve-valve and so they did not have the engineering expertise in-house to 'sweat the details'. One Kew file I saw today gave costs of resources at Napier to develop and produce the sleeves to the Bristol standard. Lots of machinery needed to be imported from the USA.

 

[J.A.W.]

Indeed, the infamous 'centerless grinders' - being purloined from P&W for Napier - story..

However, it does seem odd that the significant advances in supercharger tech were not also applied,
given the wartime need..

Unless of course, a 2-stage Sabre Tempest would make the Griffon Spitfire completely redundant..
& the industrial politics must take precedence?

 

[tartle]

Remember that at one period no new sabre 'planes were being delivered to front line units as all the new engines and spares were being used to keep what the RAF had in the air...(even Earls Court Olympia Halls were set up for Sabre overhaul to keep aeroplanes in the air.... this did improve but given the weak management and lack of technical staff at Napier would any sane Air Staff member swap horses. The Griffon II was an new beginning based on BxS of the Griffon I but incorporating features that were intended to mitigate or eliminate issues that were coming to light in intensive service; these features were proved out then fed back into the Merlin development programme.... not a trivial task with Derby, Crewe, Glasgow, Manchester and the Packard factory in USA churning out the hardware. The beauty of the setup at RR is that there were craft-based facilities at Derby to try out one-off ideas and specials; Crewe was craft plus some standard jigs and fixtures with some flow on the lines. Glasgow did most things in-house and was semi automated (no infrastructure of the right sort of skillsets existed locally). Ford was automated to a high degree and change over to different marks often meant new machine tools. The Packard team were able to incorporate the two-piece head in production before the UK as they had not got tools installed for the previous design and so could start with the latest scheme from Derby modified to suit the US production practice. Quite a planning nightmare (see Devons)!

 

[JFC Fuller]

From Sir Alec Cairncross (worked at MAP for most of the War, ultimately becoming Director of Programmes) "Planning in Wartime: Aircraft Production in Britain, Germany and the USA":

The Sabre engine was a constant headache...The design was too intricate and the sleeve valves caused endless difficulties until Banks [Francis Rodwell, a noted engine expert and ultimately given such titles as 'director general of engine production', and 'director of engine research and development'] took things in hand and forced Napier's to switch to sleeves designed by Bristol. As [Wilfred Rhodes- Chief Executive of MAP from 1942 and had of RAF R&D and industrial policy prior to 1940] Freeman told C-in-C Fighter Command in July 1943, 'the Sabre was designed without any idea of how it was going to be put together'. The truth was that the engine had been inadequately developed because the research and development staff was starved by an unadventurous management and numbered under 500 at the beginning of 1943 when Bristol had a development staff of about 1500 and Rolls Royce twice as many. It cost five times as much to manufacture as the Merlin and two and a half times as much as the Hercules....It proved as difficult to maintain as to manufacture, needing frequent replacement when in use operationally.

 

[tartle]

Frank Halford who designed Napier's wartime machines was quite cavalier in his approach to production matters.. he would get the ***dynamics right and it was up to Brodie and people like him to figure out how on earth to translate the 'design' into a producible engine.... without the boss seeing anything change. Difficult to work in that sort of environment!

 

[Hobbes]

The BRM V-16 of fighter engines. Eek!

Would that make the Sabre the BRM H-16 of fighter engines?

 

[J.A.W.]

Or as Len Setright & Bill Sweetman put it - examples of slanted anti-Sabre opinions?

From Sweetman's 'High Speed Flight'..

"By May 1942, with the Vulture long dead & buried, R-R was still trying to replace the Sabre with the Griffon, which did not match the Sabre's late `41 in service rating until 1945.
The Air Ministry's controller of R & D noted in that month:
" I have the uneasy feeling that this ( the Sabre/Typhoon development program) is suffering through all the
propaganda regarding the Griffon Typhoon.""


Halford's Sabre design was proven sound, it was poor old Napier's ancient/tottering production facilities that weren't up to it - & the needful English Electric take over was sorely belated, given the situation..

That Sabres were available - to provide the service they did, was indeed remarkable.

& while the Merlin was a winner with economies of scale, what cost all the R-R no-goes,
- the X-mills, Eagle/Sabre copy & ( sadly,IMO)-the Crecy?

 

[JFC Fuller]

Yes, it's all a conspiracy, obviously- the whole of MAP and AM were in on it, there was probably even special symbols and societies.

 

[J.A.W.]

Yes, it's all a conspiracy, obviously- the whole of MAP and AM were in on it, there was probably even special symbols and societies.

JFCF, that is quite a position to forward.. do you have evidence to support such claims?

I'd reckon it is more like 'business as usual' whether - 'cut throat' or 'the Firm comes 1st' - wartime or no..

Actually - given the profits to be made, likely - its even more so in wartime..

 

[tartle]

JFCF...very droll!
We have all we need to realise why the Sabre never reached its full potential; weak management, inadequate technical team, production started too early due to pressing military needs; complex design not worked through enough on test bed.
Far from being a copy the Eagle was a rethink of what was needed to a follow-on specification that begat the Sabre; one of the motivations for keeping Napier in the game after the Dagger was to keep up competitive pressure on Rolls. Even with the big dev team at Derby Hives knew he could not keep all the projects going. As it was pretty obvious that the big Hawker had two other engines as possibilities and the Manchester was never going to be a success even if engine worked... hence the Lancaster configuration. Rolls did have solutions running as discussed elsewhere in the forum; but Hives did not want the complexity of that engine and the Peregrine diluting resources. Incidentally Fred Morley, who worked on the Sabre told me that they were aware of the Sabre as he and others had been asked to contribute to getting it right in its early service days... this meant he knew what design principles he wanted to alter when the Sabre task came along. Superficially a Sabre-derived engine but in fact a thorough rethink as scrutinising sectioned drawings will show. The Crecy was a Ministry-sponsored project in case gas turbines took longer to get right than expected, and took a long while to develop as it only had a small dev team who were not pre-eminent in their field... I guess it helped train some engineers. The Exe, was a Rowledge project after he returned from illness, met the RN spec'n. Again Hives took the brave decision not to develop it further. So in spite of having the biggest engineering team Rolls tried to keep focussed on the V-12 configuration, whilst keeping a watching brief on other possibilities. I think its good practice.

 

[J.A.W.]

Well T, "droll" is a way of putting it..

In the 'walks like a duck, quacks like a duck' - dep't..

.. for R-R to be unsuccessful with the Vulture in the Sabre competitor stakes..
..& with the Griffon in the Sabre substitute stakes..

.. the H-24 Eagle sure looks like a case of.. 'can't beat 'em - join 'em ' ..to most..

& as the written commentaries relate, a reiteration spoiled by typical R-R design conservatism shortcomings..

T, to your knowledge, is the Eagle H-24 - lack of magneto drive redundancy - flaw story, true?

 

[J.A.W.]

R-R Eagle H-24 seems to have fallen into the same pit as the U.S. 'Hyper' H-24s..

Too heavy/bulky/lazy for effective flight utilization & too late..

 

[tartle]

Well T, "droll" is a way of putting it..


T, to your knowledge, is the Eagle H-24 - lack of magneto drive redundancy - flaw story, true?

I am afraid so!

 

[JFC Fuller]

JFCF...very droll!
We have all we need to realise why the Sabre never reached its full potential; weak management, inadequate technical team, production started too early due to pressing military needs; complex design not worked through enough on test bed.
Far from being a copy the Eagle was a rethink of what was needed to a follow-on specification that begat the Sabre; one of the motivations for keeping Napier in the game after the Dagger was to keep up competitive pressure on Rolls.

Precisely, indeed I have seen more than one source state that a major factor behind the Sabre's survival was a desire to keep Napier in business as a design house.

There is a tendency amongst many to think that a combat engine is nothing but RPM and HP. It is of course nonsense, especially when aircraft and engines become near consumables as they did 1939-45, manufacturing cost, MTBF/MTBO are equally important factors and here the Sabre fell comparatively short which is why less than 10,000 of them were made compared to 150,000 Merlins.

 

[J.A.W.]

JFCF...very droll!
We have all we need to realise why the Sabre never reached its full potential; weak management, inadequate technical team, production started too early due to pressing military needs; complex design not worked through enough on test bed.
Far from being a copy the Eagle was a rethink of what was needed to a follow-on specification that begat the Sabre; one of the motivations for keeping Napier in the game after the Dagger was to keep up competitive pressure on Rolls.

Precisely, indeed I have seen more than one source state that a major factor behind the Sabre's survival was a desire to keep Napier in business as a design house.

There is a tendency amongst many to think that a combat engine is nothing but RPM and HP. It is of course nonsense, especially when aircraft and engines become near consumables as they did 1939-45, manufacturing cost, MTBF/MTBO are equally important factors and here the Sabre fell comparatively short which is why less than 10,000 of them were made compared to 150,000 Merlins.

JFCF, feel free to provide relative TBO times for fighter use Merlins & Sabres..
You could start with the Merlins which were rated at over 2,000hp,
- since AFAIK , no Sabres were rated at less than that..

& the RAF were still working their Sabre Tempests hard - right up to the mid `50s - do note..
Can't have been too dicey mechanically though eh, especially dragging a drogue at jet interception target speeds..

 

[JFC Fuller]

Oh come of it, the Sabre maintenance issues are well documented by multiple sources.

Even right through 1942 the type had a TBO of just 25 hours and it took until 1944/45 for the production/maintenance situation to converge sufficiently to end the engine shortage.

 

[tartle]

Alec Harvey Bailey whose wartime job was in-service defect investigation and support for development of solutions quotes Merlin lives in hours as:
1939 1944/45
Fighters 240 300/360
Bombers 300 360/420
Transport 480/500
%age of total engines to reach time expiry passing through repair orgs, 1942 onwards 35% ave
Ave life of engine passing thru' rep org from 42 onwards 60% approx of nominal life for type.

 

[CJGibson]

Mere curiosity, but how was 'time expiry' defined. Hours? Wear measurement? Measurement of power ouput on a dynamomenter?

Thanks

Chris

 

[tartle]

Chris
Hours was a basic measure but as all components on a not new engine may have different lives the strip would reveal amounts of wear, burnishing, cracks etc. These would be compared with allowables in repair manual that Harvey Bailey's team would have tested at Derby and come up with a recommendation. New defects would be passed back for Defect Investigation action. Rolls had a team of people who worked with the commercial repairers to ensure they were up to scratch and to advise and teach where necessary. A very effective network which ensured, with all the other activities, the BoB pilots had a machine to fly in spite of German action! One reason the Germans got their numbers wrong for the rate of depletion of Britain's fighter force.
After all as Hives said this was a competition in which there was np point in coming second!

 

[tartle]

Back in 1938 the policy of keeping four engine firms (as laid down by Lt Col L F R Fell in 1919) was still extant and giving concern in 1938... See first attachment nelow. There is another document pointing out that Napier themselves put themselves in such a vulnerable position.
Also attached is a forecast of RR and Napier production requirements into 1940 which in hindsight makes fascinating reading!

 

[JFC Fuller]

Mr Handley Page was certainly proven correct...

I am curious to know what the Air Ministry was planning to do with Armstrong Siddeley, the Deerhound seems to have been going nowhere fast and they were clearly facing a cliff.

 

[J.A.W.]

Oh come of it, the Sabre maintenance issues are well documented by multiple sources.

Even right through 1942 the type had a TBO of just 25 hours and it took until 1944/45 for the production/maintenance situation to converge sufficiently to end the engine shortage.

Ah 1942, that would be the initial year of service for the Sabre.. ..when both it & its airframe (Typhoon)
were rushed into service to counter another high powered/performing low TBO combination in the BMW/FW 190.

Got any figures for the TBO of Griffons used in Spitfires in `43/44?

 

[tartle]

The problem with Armstrong Siddeley was J D Siddeley himself... he was autocratic in style and only wanted to produce for profit so never put any money to speak of into aero engine development. The firm put money into cars but not aviation although they did acquire AVRO and High Duty Alloys and let them get on with it.
All the aero companies constructed 'Shadow Factories' during the 1930s and geared up for war. Armstrong Siddeley produced nearly 30,000 Cheetah (a development of the Lynx) aero engines for Avro Anson etc, thousands of tank gearboxes, thousands of torpedo engines and gyroscopes and the Whitley bomber. It also undertook development of the Deerhound engine and was a subcontractor working on Merlin engines, Lancaster cockpits and bomb doors.

 

[JFC Fuller]

1941 was the first year of service for the Typhoon, No.56 squadron first received the type in September of that year but it was so unreliable (primarily the engine) that the squadron was not declared fully operational until 30th May 1942.

To be fair to the type it then remained in service and production, with only relatively minor modifications, for over three years after that (even though the engine continued to be maintenance heavy) quite a feat for a WW2 fighter and in many ways reminiscent of that fractionally earlier (by about eighteen months/two years) RAF attempt at a high performance four hispano single seater, the Whirlwind, which ultimately also managed three years of successful operations in a very similar role; it was expensive, maintenance heavy, and took a long time to get right but ultimately proved a very effective fighting machine.

 

[JFC Fuller]

Tartle,

Indeed, Armstrongs was a generic engineering firm that happened to have some aviation in it whereas the others were, by comparison, more focussed. The curious thing for me was what the Ministry thoughts were to the company in 1938/40, AS engines don't appear in any of the major programmes at that time.

 

[tartle]

JFCF,
There was the minor problem of the tails coming off. The whole Typhoon programme was nearly abandoned in October 1942 but Roland P Beamont had recently been appointed to lead 609 sqdn who had become the 2nd squadron to reequip with Typhoons.
Bee had been rested from front line duties by being assigned to Hawkers to act as a test pilot. This spell in Hawkers had given him a taste for test flying, particularly the powerful and punchy Typhoon. He was therefore delighted to be posted, in June 1942, from Hawkers to No 56, the first operational squadron to be re-equipped with Typhoons and after a month to No 609, the West Riding Auxiliary Air Force squadron. Arriving at 609 as a flight commander, Beamont began to lead the "Tiffies" on low-level day and night intruder and ground attack operations across the Channel. It was largely due to Beamont's inventive employment of the Typhoon as a fighter-bomber that he gained steadily increasing respect for himself and a type of aircraft then still regarded as decidedly dodgy. Bee was summoned to a meeting called by the C-in-C Leigh Mallory at the end of 1942. To his astonishment he found a lobby of Engineering Branch officers backed up by Spitfire men opposed to continued production of the Typhoon as a waste of resources on the grounds it was an inferior machine not suitable for fighter command... Bee spoke out against them arguing that the Typhoon was 'undoubtedly superior to the Spitfire for all purposes at low level'. When it was found that none of the opposition had actually flown a Typhoon the aircraft was given a stay of execution... in the meantime it was up to Squadron Leader Beamont and his squadron to show what they could do with it. Bee had already developed the technique of night time locomotive-busting rhubarbs and continued to show HQ the potential for using the Typhoon at low altitude; eventualyl HQ realised that the role for thee aircraft was different to that of the Spit and both programmes survived. Reliability of the engine was an issue with 609 at one point having 35 pilots and six operational Typhoons.
I think I posted this chart before but here it is again.

 

[J.A.W.]

1941 was the first year of service for the Typhoon, No.56 squadron first received the type in September of that year but it was so unreliable (primarily the engine) that the squadron was not declared fully operational until 30th May 1942.

To be fair to the type it then remained in service and production, with only relatively minor modifications, for over three years after that (even though the engine continued to be maintenance heavy) quite a feat for a WW2 fighter and in many ways reminiscent of that fractionally earlier (by about eighteen months/two years) RAF attempt at a high performance four hispano single seater, the Whirlwind, which ultimately also managed three years of successful operations in a very similar role; it was expensive, maintenance heavy, and took a long time to get right but ultimately proved a very effective fighting machine.










Yes, 'to be fair', Typhoons had managed a year in service by late `42..

From D.N. James - 'Hawker, An Aircraft Album';

"...in the face of suggestions to withdraw it from service, the Typhoon used its excellent low level performance
in No 609 Sqdn to beat the tip-&-run raiding Focke-Wulf 190 fighter-bombers along the south coast of England
beginning in November 1941."

Those operations obviously required working their Sabres fairly hard, & what were the TBOs managed by
the 'clipped cropped & clapped' over-boosted Merlins in Spits - given the same task?

Only ~100 Whirlwinds were built & were disliked by the Spitfire 'mafia' - maybe even more than Typhoons..

They were kept out of the Battle of Britain - up north - well away from 11 Group, who 'didn't want passengers'
- or words to that effect..

Whirlwinds were out of their depth against the FW 190 too, viz - 'The Channel Dash' where a bunch got the chop..

 

[J.A.W.]

Youthful Kiwi Group Captain Desmond Scott took over 486 (NZ) Sqdn in mid `43, & he related that..

"By this time the Typhoon had mended its ways... &... once it had settled down...for all its faults...
it was to become the greatest low attack aircraft of the 2nd World War. Tough, pugnacious, uncompromising
it might have been, but loaded with bombs or rockets it became the nightmare of the Wehrmacht's skies"

& he goes on to compare it with the P-47..

"The pot-bellied Thunderbolt was not unlike the Typhoon in some respects. Powerful, large & heavy,
it would made a suitable American wife for its British counterpart. (!)
The Typhoon had the edge over it low down, but the Thunderbolt excelled in the higher altitudes."