WW2 with no Spitfire - Hurricane being primary interceptor

FLYBOYJ · May 16, 2013

With all this talk about how "difficult" the Spitfire was to build, maintain and repair.....

"In 1986, the historian Corelli Barnett upset enthusiasts by suggesting the Spitfire took twice as many work-hours to build as the Messerschmitt Bf 109. It seems he took his figures from earlier production in Southampton. In fact, Castle Bromwich achieved tremendous rates for mass production that rivalled German and even American factories."
Science Museum | Inside the Spitfire | Production rates

A great little site....

Science Museum | Inside the Spitfire | Inside the Spitfire

So I'm waiting for someone to tell me about these special processes that made the Spitfire soooo difficult to build...

Shortround6 · May 16, 2013

RCAFson said:
I provided a quote from Mason showing that even in the UK, that Spitfires often had to be trucked out for repairs from less developed based, while Hurricanes with similar damage could be repaired on site. The Hurricane used a construction method that was used for several decades prior to WW2 and therefore base service personnel even in the MTO were familiar with it, but even in the UK they were not universally familiar with stressed skin monocoque airframes.

Several decades, as in 2 or more, puts you to 1919 and before, darn few welded tube fuselages in use then. Metal Structure had to Specified by the Air Ministry in the late 20s I believe just to get the manufacturers to give up on wood primary structure. In the early to mid 30s with many of the "Erks" being long term (career) servicemen sticking with what they knew made some sense. Once you get to the rapid build up of the late 30's and 1st year or two of the war only the most senior men and NCO supervisors are going to have any real experience with fabric covered aircraft. The new "tradesmen" are going to know what they were taught in the training schools. The practice of training on old hulks is certainly cheap but does slow down the introduction of better aircraft.

Send up the Hurricanes instead of Spitfires, the tradesmen will get plenty of practice patching them back together

Shortround6 · May 16, 2013

The Basket said:
My point is that there were a nunber of aircraft manufacturers...back in the day....who could build a merlin powered single seat machine.

Supermarine was one of many so as per my thoughts ask Fairey as they have experience with metal machines.

there seems to be a little confusion here. The RAF gave up on "non-metal" machines about 10 years before the war started. The covering, which on fabric covered machines was non-structural, was sometimes NOT counted when describing a machine as "ALL metal." The Term "ALL metal" served to distinguish an airplane or airframe from one that used a Metal framed fuselage and wooden framed wings ( or perhaps the other way round, not common) or metal structure fuselage, metal spars and wood ribs or some combination where wood was still used as a structural member.
Most manufacturers in England had experience with metal structures even if not "stressed skin". A number of British companies had experience with "stressed skin", Fairey was certainly one of them, Bristol another, Handley Page yet another.
A few companies used metal covering of a tube framework which is not quite the same thing.

Fairey may have been able to come up with a "merlin powered single seat machine" but if it was to be successful the ONLY things it could share with the Battle were the Merlin engine, the low wing placement and being a monoplane with retractable landing gear, the very basic concept. ANY attempt to use Battle parts, assemblies or structure would doom the aircraft.

RCAFson · May 16, 2013

Shortround6 said:
Several decades, as in 2 or more, puts you to 1919 and before, darn few welded tube fuselages in use then. Metal Structure had to Specified by the Air Ministry in the late 20s I believe just to get the manufacturers to give up on wood primary structure. In the early to mid 30s with many of the "Erks" being long term (career) servicemen sticking with what they knew made some sense. Once you get to the rapid build up of the late 30's and 1st year or two of the war only the most senior men and NCO supervisors are going to have any real experience with fabric covered aircraft. The new "tradesmen" are going to know what they were taught in the training schools. The practice of training on old hulks is certainly cheap but does slow down the introduction of better aircraft.

Send up the Hurricanes instead of Spitfires, the tradesmen will get plenty of practice patching them back together

no welding in the fuselage:

Fuselage :-

Rectangular rigidly braced structure of steel and aluminium-alloy square-ended tubing assembled by flat-plate fittings and hollow rivets, faired to an oval section and covered forward with detachable metal panels and aft with fabric over light wooden formers.
K5083 - Technical Data

Essentially the same methods were used from the mid 1920s, 30s and early 1940s (hurricanes) on all Hawker fighters, hence several decades.

RCAFson · May 16, 2013

FLYBOYJ said:
With all this talk about how "difficult" the Spitfire was to build, maintain and repair.....

"In 1986, the historian Corelli Barnett upset enthusiasts by suggesting the Spitfire took twice as many work-hours to build as the Messerschmitt Bf 109. It seems he took his figures from earlier production in Southampton. In fact, Castle Bromwich achieved tremendous rates for mass production that rivalled German and even American factories."
Science Museum | Inside the Spitfire | Production rates
A great little site....

Science Museum | Inside the Spitfire | Inside the Spitfire

So I'm waiting for someone to tell me about these special processes that made the Spitfire soooo difficult to build...

The Spitfire was hard to build:

Appendix B

COMMENTS BY JEFFREY QUILL ON PUTTING THE SPITFIRE INTO PRODUCTION

The extracts from the minutes of the Air Ministry meetings about the early problems of Spitfire production, tend to put the whole blame for the early production delays upon Supermarine and Sir Robert McLean They should be read bearing in mind certain considerations.

Of course it was right that Supermarine, as prime contractor, should carry the main burden of responsibility for the delays But since the main cause of delay was the lateness of the wings, it was obviously unrealistic to absolve from all blame the sub-contractors responsible for wing production.

It should also be remembered that technologically the Spitfire had a much more advanced structure than the Hurricane and other contemporary types, and was therefore much more difficult to put into production. The problem of forecasting production accurately was correspondingly more difficult than for other types.

The Air Ministry, who were on bad terms with McLean at that time anyway, were naturally highly critical of him for having made over-optimistic forecasts of production dates. But if, in June 1936, McLean and Supermarine had made coldly pessimistic forecasts, emphasizing the difficulties of producing this very advanced aircraft, the Air Ministry might well not have ordered the Spitfire into production at all. There were plenty of people in official positions in 1936 who were saying that the

Spitfire would be far too difficult to produce and maintain in service, and that its margin in performance over the Hurricane was not worth the extra effort. Clearly the firm was not keen to add fuel to that particular fire. Although in hindsight the company s initial forecasts can be seen to have been optimistic they were not irresponsibly so, because the difficulties were all overcome in time. Although McLean's initially optimistic stance may have had an element of commercial tactics about it, events proved that it was just as well for us all that he adopted it.

The root cause of the problems of getting the Spitfire into mass production really lay in the years of neglect of the aircraft industry, by successive governments up to 1936. At the last possible moment they initiated the re-armament programme and expected an industry starved of orders since 1919 suddenly to increase production capacity by four or five times, and change over to building far more complex types of aircraft, all within a space of just two or three years. Of course there were going to be enormous problems and with the best will in the world mistakes were going to be made. It was all very well for the Air Ministry to say to Supermarine 'What you can't do yourselves you must sub-contract'. But where were subcontractors to be found with the necessary experience, on the fringes of an industry which hitherto had hardly sufficient orders to keep itself alive?

The Spitfire Story, p69.

From Sydney Camm and the Hurricane, p.152:

Actual manhour figures for production aircraft are not now available, but Air Ministry/MAP planning in early 1940 was based on an airframe structure weight of 2,468 lb. requiring an average of 10,300 manhours. The comparable numbers for the Spitfire were 2,055 lb and 15,200 manhours. The resulting figures of 4.17 and 7.40 manhours per lb respectively for the Hurricane and the Spitfire are an indication of the advantages given in production by the much simpler design of the Hurricane. This factor enabled the necessary numbers of aircraft to be made available in good time to meet the first onslaughts of the war and permitted the high output rates that made the type available for use in all theatres of war until it was superseded in front-line service by the Typhoon and the Tempest.

At the outbreak of war, the RAF had received 497 aircraft, all Hawker-built and all delivered from Brooklands. By 7th August 1940, when the second phase of the Battle of Britain was beginning official reports record 2,309 Hurricanes had been received, and they then equipped 32 RAF squadrons. Comparable figures for the Spitfire were 1,400 air craft delivered and 19 squadrons equipped.

wuzak · May 16, 2013

RCAFson said:
The gear ratios were not the same, but as we've discussed, the gear change leads to a loss in power because it has to be throttled back prior to gear changing, plus there is the additional weight and complication of the two speed gear box with it's attendant reliability issues, which is probably why the 45 was rated for 16lb boost almost a year sooner than than the XX. Additionally, the gear ratio of the 45 was better suited for medium altitude where much of the fighting took place but the main advantage was the simpler engine management with increased reliability, but as always the XX will not go away, but as there will be a lot more Hurricanes, both engines will be needed to meet demand, and for differing roles.

The loss of power from a XX to a 45 is because it is pulling a higher gear. That is, the supercharger is operating at a higher pressure ratio, which means more power to compress the air. The gears themselves don't make any difference to the power being consumed.

As regards to throttling, you must understand that the Merlin was throttled up to the Full Throttle Height. For the XX it is throttled until FTH in MS gear - around 6,000ft @ +9psi boost. The throttle remains open from that point until the gear change, but the engine cannot sustain that level of boost. The power drops slightly. Then the gear change happens, and the engine is throttled again - but now, thanks to the higher gear, it is making full boost, but less power because it takes more power to compress the air.

I was using the example of the FS gear in the XX being the same as the gear in the 45 to illustrate that once the XX is in FS gear the two engiens would be throttled the same amount at any given altitude above the change point.

I have just highlighted the power curve of the XX (I think it says +14psi boost) in green.

The red line is what the power curve would be if that engine cold only use the FS gear.

I would suggest that the 45 was rated for +16psi boost earlier than the XX was because it needed the higher rating more. The higher boost lowers the FTH and gives more power at that lower FTH. But at higher altitudes the power falls back to be the same as the lower rating at the FTH for the lower rating. In essence compensating for having a single speed.

Simpler engine management? I thought the XX had automatic gear changes, but if not it certainly had automatic throttle control.

Shortround6 · May 16, 2013

Lets take a look at the lower altitudes or take-off since they can be found. Merlin XX has 1280hp at 3000rpm and 12 lbs boost. Merlin 45 has 1185 hp at 3000rpm and 12 lbs boost. Merlin XX has less need of over boosting since it has 95hp more to begin with at low level. And in climb it will have around 85-95hp more at the SAME RPM and BOOST up until over 10,000ft.

Look at the chart so kindly provided by Wuzak. Merlin XX used 8.15 and 9.49 gears while the Merlin 45 used 9.089 gears. Power used goes up with the square of the speed of the impeller.

At 2850rpm and 9lb boost (climb limit for both engines) the Merlin XX is going to have 20-50hp more power from sea level to around 11,000ft.

Pick a condtion (rpm and boost) and draw a line 1/3 of the way above the high gear line and 2/3 of the way below the low gear line of the Merlin XX from the lest side of the chart to the appropriate right hand downward slopping line and you should be pretty close to the Merlin 45 power for that condition. extend the right line as needed closer to the ground.

Using higher than "normal" boost Like 16lbs if "normal" was considered either 9lb or 12lbs at the time called for notations in the log books, reduced time to overhaul if done enough and extra maintenance on the engine. It was not a freeby.

RCAFson · May 16, 2013

The XX had manual SC gear change, and the clutch and gears gave some trouble until made reliable after a number of mods.

wuzak · May 16, 2013

RCAFson said:
The XX had manual SC gear change, and the clutch and gears gave some trouble until made reliable after a number of mods.

You mean they didn't find the problems and fix them in the X?

RCAFson · May 16, 2013

wuzak said:
You mean they didn't find the problems and fix them in the X?

The X was fairly reliable but was also a low boost engine:

On single speed engines, there was a bronze pad slipper drive in the layshaft gear to provide a smooth take-up of sudden changes in crankshaft speed. This assembly gave no trouble....

...The Merlin X gave no trouble but as production of higher rated engines from new factories increased so did the problems. Clutch reliability was finally obtained by detail action in a number of areas. First the timing of the operation was important to ensure that there was a clean change. With multi-plate clutches the amount of free movement in the disengaged position had to be controlled to about 0.030 in. With less end float the clutches tended to drag when not in use and overheat, and if there was too much end float the geometry was such that in the loaded condition the fingers could contact the withdrawal race causing clutch slip and burn out.

The issues turned on getting good solid clutches with adequate friction plate bedding. In rivetting the linings to the plates one could get a series of waves and high spots which wore rapidly and increased end float. This was cured by attention to the backing plates for flatness, care in rivetting

Harvey-Bailey, p48-49.

He goes on to mention that the gears and gear box also gave some trouble. Anyways, it seems pretty clear that the two speed drive had a few problems and that they increased along with boost levels so I suspect that the XX would be better suited to high altitude, or low altitude work where gear shifts could be minimized, but for medium altitude work, the 45 would be more reliable.

wuzak · May 16, 2013

At the outbreak of war, the RAF had received 497 aircraft, all Hawker-built and all delivered from Brooklands. By 7th August 1940, when the second phase of the Battle of Britain was beginning official reports record 2,309 Hurricanes had been received, and they then equipped 32 RAF squadrons. Comparable figures for the Spitfire were 1,400 air craft delivered and 19 squadrons equipped.

How much of that 900 difference is down to the earlier start to Hurricane production, and how much to early difficulties with Spitfire production? By teh BoB it would seem Spitfire production was in full swing!

Aozora · May 16, 2013

RCAFson said:
The Spitfire was hard to build:

From Sydney Camm and the Hurricane, p.152:

Note that the comments from The Spitfire Story are mostly based on opinions from 1936 when some people in the ministry were saying the Spitfire would be hard to build:

It should also be remembered that technologically the Spitfire had a much more advanced structure than the Hurricane and other contemporary types, and was therefore much more difficult to put into production. The problem of forecasting production accurately was correspondingly more difficult than for other types. The Air Ministry, who were on bad terms with McLean at that time anyway, were naturally highly critical of him for having made over-optimistic forecasts of production dates. But if, in June 1936, McLean and Supermarine had made coldly pessimistic forecasts, emphasizing the difficulties of producing this very advanced aircraft, the Air Ministry might well not have ordered the Spitfire into production at all. There were plenty of people in official positions in 1936 who were saying that the Spitfire would be far too difficult to produce and maintain in service, and that its margin in performance over the Hurricane was not worth the extra effort.

Wow what a revelation! The Spitfire was considered to be hard to build in 1936 by some in the Air Ministry, at a time when the entire aircraft industry was only just coming to terms with mass producing the all metal, monocoque structure. For the rest the problems introducing the Spitfire into production had a great deal to do with Supermarine's difficulties in learning how to draft blueprints and generally prepare for mass production.

This is just a reiteration of these stupid myths about what a difficult aircraft the Spitfire was to build and maintain:

*IF the Spitfire had been so hard to build it would have been impossible to run the dispersal scheme after the Southampton factories had been bombed out.

*British industry was already fully capable of mass producing motor vehicles which had panels and bodywork full of compound curves and complex shapes, so building such shapes into aircraft was not the huge leap that some seem to believe.

*The most complex and difficult to service component in the Spitfire was the engine.

This factor enabled the necessary numbers of aircraft to be made available in good time to meet the first onslaughts of the war and permitted the high output rates that made the type available for use in all theatres of war until it was superseded in front-line service by the Typhoon and the Tempest.

In fact the Hurricane was mostly superseded by the Spitfire - guess how many Typhoons entered service in North Africa? Malta? How many Typhoons served in Australia and the Pacific?

Fact is that Hawker stuck to the tube and fabric construction for so long that when it came to developing and building the all metal monocoque structure for the Typhoon Hawker struck real problems. Sticking to decades old structural solutions retarded development of the Hurricane's successor.

FLYBOYJ · May 16, 2013

RCAFson said:
The Spitfire was hard to build:

From Sydney Camm and the Hurricane, p.152:

by two people making comments early in the production who probably never built an entire aircraft (yes, that includes Sydney Camm) and over 20,000 aircraft later I'm sure we'll take their opinions with a grain of salt. You're quoting resources from people who higher on the totem pole than the average assembler or mechanic, so until you can give specifics, you're quoting here-say, opinions and empty information.

RCAFson · May 16, 2013

Aozora said:
Note that the comments from The Spitfire Story are mostly based on opinions from 1936 when some people in the ministry were saying the Spitfire would be hard to build:

Wow what a revelation! The Spitfire was considered to be hard to build in 1936 by some in the Air Ministry, at a time when the entire aircraft industry was only just coming to terms with mass producing the all metal, monocoque structure.

This is just a reiteration of these stupid myths about what a difficult aircraft the Spitfire was to build and maintain.

Once again IF the Spitfire had been so hard to build it would have been impossible to run the dispersal scheme after the Southampton factories had been bombed out.

My god man - you do realize that Jeffrey Quill wrote that? It wasn't just the AM who considered it hard to build, it was hard to build and Supermarine had a heckuva time getting it into volume production. Yes, eventually good production rates were achieved but only after investing and spending massive amounts of scarce capital on the various factories and their needed tooling. Only 49 Spitfires were delivered by Jan 1939. The first 310 Spitfires were contracted to cost 1.395 million pounds but actually cost 1.870 million and were delivered over a year late. In contrast the Hurricane met and exceeded it's production targets.

In fact the Hurricane was mostly superseded by the Spitfire - guess how many Typhoons entered service in North Africa? Malta? How many Typhoons served in Australia and the Pacific?

Fact is that Hawker stuck to the tube and fabric construction for so long that when it came to developing and building the all metal monocoque structure for the Typhoon Hawker struck real problems. Sticking to decades old structural solutions retarded development of the Hurricane's successor.

Hawker's problems came after they established a very high production volume of low cost Hurricanes. If Hawker had gone monocoque route in 1935/6 the UK would probably have lost the BofB.

The Spitfire was hard to build and the 2nd quote (Sydney Camm and the Hurricane) shows that:

Actual manhour figures for production aircraft are not now available, but Air Ministry/MAP planning in early 1940 was based on an airframe structure weight of 2,468 lb. requiring an average of 10,300 manhours. The comparable numbers for the Spitfire were 2,055 lb and 15,200 manhours. The resulting figures of 4.17 and 7.40 manhours per lb respectively for the Hurricane and the Spitfire are an indication of the advantages given in production by the much simpler design of the Hurricane. This factor enabled the necessary numbers of aircraft to be made available in good time to meet the first onslaughts of the war and permitted the high output rates that made the type available for use in all theatres of war until it was superseded in front-line service by the Typhoon and the Tempest.

FLYBOYJ · May 16, 2013

RCAFson said:
no welding in the fuselage:.

During "ASSEMBLY" the cross members were bolted to the mainframes. In the field if you didn't have replacement cross members, what was left?!?! You really need to think about what you're quoting and maybe talk to some folks who have worked on these things!

There is no doubt the Hurricane was easier to build but these comments were made by folks very early in an aircraft assembly revolution. In hindsight, the spit fire was no harder to build than many of its contemporaries...

nuuumannn · May 16, 2013

RCAFson, you are taking those quotes out of context. The Spitfire was more difficult to build in the minds of these individuals at that time due to the reasons pointed out earlier, such as (why they need to be reiterated here just shows how much you are prepared to ignore the same advice over and over again) Supermarine's work force, the state of the British industry etc, NOT because there was anything inherently complicated about the Spitfire's structure, otherwise there wouldn't have been over 22,000 of them built. Today, restoring Spitfires is a less complex task than it is to restore Hurricanes due to the structural differences between the two. The technicques being used to build Hurricanes during the war have more or less died out, so it is a more difficult and lengthier undertaking to restore one, compared to a Spitfire, whose structural materials and processes differs little from aircraft being built today.

When Castle Bromwich was up and running at full steam there was an average of thirty Spitfires rolling off the line in a month; beaking it down, that averages to one every day within that time period.

RCAFson · May 16, 2013

nuuumannn said:
RCAFson, you are taking those quotes out of context. The Spitfire was more difficult to build in the minds of these individuals at that time due to the reasons pointed out earlier, such as (why they need to be reiterated here just shows how much you are prepared to ignore the same advice over and over again) Supermarine's work force, the state of the British industry etc, NOT because there was anything inherently complicated about the Spitfire's structure, otherwise there wouldn't have been over 22,000 of them built. Today, restoring Spitfires is a less complex task than it is to restore Hurricanes due to the structural differences between the two. The technicques being used to build Hurricanes during the war have more or less died out, so it is a more difficult and lengthier undertaking to restore one, compared to a Spitfire, whose structural materials and processes differs little from aircraft being built today.

No, you are taking them out of context and trying to place into a modern context. The UK in 1936-39 was what it was, and in that context the Hurricane was much cheaper and faster to build and required a minimum of new tooling. The AM figures from 1940 gives us proof positive of the comparative cost of each in the early war years and it took about 50% more man hours to build a Spitfire than a Hurricane - these "numbers didn't exist in the minds of these individuals", they were real comparative costs.

The Spitfire was built in larger numbers, eventually and with massive assistance via lend-lease machine tools and related equipment, but it was also in production even after the war, where Hurricane production ended in Aug 44 in the UK and early 1943 in Canada. Building them in large numbers doesn't mean they were easy to build as volume production will bring down the cost of any complex machine. The cost of restoring a Hurricane now is irrelevant; it was the cost of building and repairing them then that mattered, especially during the year starting with the FoF when ease of production made the Hurricane a decisive factor in the BofB and period ending with the US entry into the war.

nuuumannn · May 16, 2013

and in that context the Hurricane was much cheaper and faster to build and required a minimum of new tooling.

At that time, yes, the Spit WAS considered difficult, but not as a whole. Again, the reason why the Hurricane was easier to build back then was because the industry was geared up to build them, NOT extensive sheet metal work! How often do you need to be told that before it'll sink in!? Cost has nothing do do with how difficult they were to build. Today's sheet metal processess differ little from back then - tooling and technique is little different except skin bashers these days choose to wear ear defenders and and use tungsten dollies (which make rivet forming soooo much easier), so yes, a direct comparison CAN be made to today's environment; the difference being is because the processes to build the Hurricane are no longer in use.

FLYBOYJ · May 16, 2013

RCAFson said:
and required a minimum of new tooling.

Can you elaborate or are you going to just sidestep again because you really don't know what type of "TOOLING" is used to build an aircraft?

Aozora · May 16, 2013

RCAFson said:
My god man - you do realize that Jeffrey Quill wrote that? It wasn't just the AM who considered it hard to build, it was hard to build and Supermarine had a heckuva time getting it into volume production. Yes, eventually good production rates were achieved but only after investing and spending massive amounts of scarce capital on the various factories and their needed tooling. Only 49 Spitfires were delivered by Jan 1939. The first 310 Spitfires were contracted to cost 1.395 million pounds but actually cost 1.870 million and were delivered over a year late. In contrast the Hurricane met and exceeded it's production targets.

Yes I am fully aware of who wrote that and I am fully aware that you have taken one or two quotes out of context to "prove" whatever case you are trying to prove. Read Chapter 3 of The Spitfire Story and get some basic facts straight before you claim, over-simplistically, that the Spitfire was too complex to get into production.

For example, both Supermarine and Vickers were short staffed in the mid to late '30s: in addition the Vickers chairman Sir Robert McLean refused to allow subcontractors to build Spitfires:

After a great deal of pushing General Aircraft Limited (GAL) was allowed to build components of the Spitfire but Supermarine was unable to supply the necessary blueprints etc because of a lack of staff in the technical office:

Plus there were delays because Supermarine were not supplying some small components to subcontractors who were already building major components in numbers:

But I guess you're going to reiterate your usual simplistic blather to keep your "case" rolling for another 20 pages or more. Fact is the Spitfire was built, in spite of your regrets, and the fact is it helped beat the Luftwaffe before and during the B of B. There are a lot of pilots who owe their lives to the superior performance of the Spitfire over the Hurricane. END OF STORY

WW2 with no Spitfire - Hurricane being primary interceptor

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