Spitfire Combat Radius (range) evolution, limitations?

[EwenS]

Why did the IX continue after the VII/VIII?

One way of understanding this is to try to understand which company / factory produced which versions.

Supermarine, the parent company produced virtually every version of the Spitfire (except Mk.II)

Westland was brought in to the production scheme early and after 50 Mk.I it switched to Mk.V and then to Seafire production in 1942.

Cunliffe Owen was a major sub-contractor who was later brought in as a second source for Seafire production in 1943.

Then we have the Castle Bromwich Aircraft Factory, a shadow factory built in 1936-40

Castle Bromwich Assembly - Wikipedia

en.m.wikipedia.org

It was set up for mass production and built a progression of types. Starting with Mk.II from June 1940, it moved on to Mk.Vb/Vc and then the IX/XVI, all building on the versions that preceded it, or that were sometimes initially built in parallel. The plan was then for it to move to the intended next mass produced version, the Griffon engined F.21/22 from late 1944.

The Griffon engined Mk.XIV & XVIII were only ever intended to be produced short term pending the arrival of the fully sorted F.21 with the new aileron and wingtip shape designed to restore some of the Spitfire's manoeuvrability. That took much longer to sort out than anticipated with the result that the first F.21 squadron didn't receive its aircraft until March/April 1945. That was 91 squadron followed by 1 squadron in May. So pending full production of the F.21/22 CBAF continued producing Mk.IX/XVI to keep the workforce together.

You will find plenty of information on individual Spitfire contracts here

contract summary

www.airhistory.org.uk

And a searchable Spitfire database here

Spitfire pilots and aircraft database -

The Mk.IX was initially only intended as a stopgap to get the Merlin 60 engine into a Mk.V airframe as a matter or urgency in 1942. The intention was that the fully refined Merlin 60 version would be the Mk.VIII. As it turned out, the performance difference was negligible so CBAF kept producing it rather than have the disruption of making more changes to the production line by switching to the Mk.VIII.

You will find notes about the various Spitfire versions here.

List of Spitfire and seafire marks along with recognition points

dingeraviation.net

 

[pbehn]

It was usually figured to be about 6mph for the external BP glass.

Thanks I couldnt remember the figure and my computer was playing up. There were lots of things at the time like fitting cannon rear view mirrors and changes to rivet type, I was surprised it had any effect at all, but that's why I don't design aircraft.

 

[Zipper730]

One way of understanding this is to try to understand which company / factory produced which versions.

That's a pretty interesting set of information. I didn't know Westland was responsible for the Spitfire Mk.V, though I'll note the Westland Whirlwind has a retractible gear.

It would appear that some Spitfire Mk.I/II were converted into Mk.V's at Supermarine. I'm curious if this precluded a retractible wheel from being included?

The plan was then for it to move to the intended next mass produced version, the Griffon engined F.21/22 from late 1944.

And there were problems that had to be sorted out with the wing-design that took longer than expected. I'm curious what those were from a purely intellectual standpoint.

From what I heard the Mk.21/22 was to incorporate a modified version of the wing that had laminar-flow features, correct?

 

[EwenS]

That's a pretty interesting set of information. I didn't know Westland was responsible for the Spitfire Mk.V, though I'll note the Westland Whirlwind has a retractible gear.

It would appear that some Spitfire Mk.I/II were converted into Mk.V's at Supermarine. I'm curious if this precluded a retractible wheel from being included?

And there were problems that had to be sorted out with the wing-design that took longer than expected. I'm curious what those were from a purely intellectual standpoint.

From what I heard the Mk.21/22 was to incorporate a modified version of the wing that had laminar-flow features, correct?

Westland built the Mk.V, as did Supermarine and CBAF, but I wouldn't describe them as "responsible" for it. Supermarine were "responsible" for its development along with Rolls Royce for the new engine.

The successor to the Mk.I/II was intended to be the Mk.III. That aircraft would have had a new engine, clipped wings and a retractable tail wheel. But events intervened. The Mk.V began as an attempt to match the performance of the Bf109F that began to appear over southern England in Nov 1940. The route was to put a new engine in the Mk.I/II airframe as it was needed in service urgently. From initial discussions on Christmas Eve 1940 to having a prototype Mk.V for trials took 7 weeks. By the end of Feb 1941 the first conversions were in service with 92 squadron. By the beginning of March all thoughts of the Mk.III were ditched and the serial numbers allocated to that Mark on order switched to the Mk.V. As time went on other changes, like the Universal wing, were introduced to the Mk.V.

Remember the aphorism that the enemy of good is perfect.

From late 1942 Supermarine was working on new wings for the Spitfire. As their experience with new wing profiles was limited they decided on a two step approach.
1. Produce a high speed wing by modifying the existing Spitfire wing by raising the leading edge by 2 inches and if tests on that proved successful,
2. Design a completely new laminar flow wing.

The former became the wing fitted to the Spitfire F.21 and subsequent Spitfires/Seafires. The latter became the wing first tested on a converted Mk XIV, NN660, from June 1944 that was eventually fitted to the Spiteful/Seafang and later the jet powered Attacker.

File:Supermarine Spiteful.png - Wikimedia Commons

commons.m.wikimedia.org

As for the F.21 wing there is some information here

Concise Guide To Spitfire Wing Types — Variants & Technology | Reference

The object of the F.21 wing was to increase the limiting speed of the Mk.XIV above 470mph by improving the aileron control. That meant bigger ailerons which changed the wing tip shape. When the first F.21 appeared in July 1944 there were problems with aileron tab gearing, aileron control being too light, directional stability required a rudder of increased chord. Spitfire The History has details of all the test flights and changes needed.

Ultimately, when the F.22, with the cut down rear fuselage, was built it was given a larger tailplane designed for the Spiteful that was 27-28% larger to cure some of the issues from the F.21.

 

[tomo pauk]

The successor to the Mk.I/II was intended to be the Mk.III. That aircraft would have had a new engine, clipped wings and a retractable tail wheel. But events intervened. The Mk.V began as an attempt to match the performance of the Bf109F that began to appear over southern England in Nov 1940. The route was to put a new engine in the Mk.I/II airframe as it was needed in service urgently. From initial discussions on Christmas Eve 1940 to having a prototype Mk.V for trials took 7 weeks. By the end of Feb 1941 the first conversions were in service with 92 squadron. By the beginning of March all thoughts of the Mk.III were ditched and the serial numbers allocated to that Mark on order switched to the Mk.V. As time went on other changes, like the Universal wing, were introduced to the Mk.V.

The lack of Merlin XXs probably had a lot to do with non-introduction of the Spitfire III already for the BoB IMO. Hurricane acutely needed 'heart transplant' in order to cancel out the performance gap vs. Bf 109E,, and Merlin XX provided that.
Merlin XX was also in need for Defiant and Beaufighter.

 

[EwenS]

The lack of Merlin XXs probably had a lot to do with non-introduction of the Spitfire III already for the BoB IMO. Hurricane acutely needed 'heart transplant' in order to cancel out the performance gap vs. Bf 109E,, and Merlin XX provided that.
Merlin XX was also in need for Defiant and Beaufighter.

As for the Dec 1940 meeting, the way it is put in " Spitfire The History"

"The Merlin XX engine would have provided power for the Spitfire to fight off the 109F, but it was a fairly complex engine, more difficult to produce than previous Merlins. It had a low-altitude blower and this feature was hindering large scale production. Rolls Royce suggested that the pertinent blower be deleted in order to produce an engine with the necessary high-altitude performance. The final result was the emergence of the Merlin RM 5S or Mk45, which was to increase the Spitfire's ceiling by 2,000 feet. Mr Hives, for Rolls Royce, said he could provide at least 300 of the modified Merlins by 1 March and a further 200 by 1 April. He also stated that this would not affect Merlin XX production. Sholto-Douglas, also present, said ....'We will have to reserve the entire production of this new engine for the Spitfire as this will be a priceless asset in the struggle for air superiority over the south-east corner of England'."

 

[tomo pauk]

As for the Dec 1940 meeting, the way it is put in " Spitfire The History"

"The Merlin XX engine would have provided power for the Spitfire to fight off the 109F, but it was a fairly complex engine, more difficult to produce than previous Merlins. It had a low-altitude blower and this feature was hindering large scale production. Rolls Royce suggested that the pertinent blower be deleted in order to produce an engine with the necessary high-altitude performance.

Thank you for the excerpt.
We can word a thing or two better, though. There was just one blower on either the Mk.XX or MK.45 (or on the Mk.III for that matter). Blower drive was different - a 2-speed gearbox ('MS' and 'FS - or, roughly, low-altitude and high-altitude gearing) for the Mk.XX, and one-speed gearbox ('FS' only - or, high altitude) for the Mk.45. One the Mk.45, the same step-up gearing was used as on the Mk.XII, namely 9.09:1.

Great demand for the Mk.XX coupled with it being a bit more complicated to make than the 1-speed engine of the same family indeed meant a lack of these in 1940. Mk.45 featured the much improved intake before the impeller as it was found on the Mk.XX, and shared the improved impeller with the Mk.X and Mk.XX, thus the performance above ~10000 ft was indeed about the same as on the Mk.XX.

 

[Shortround6]

Apparently there was some misunderstanding of what was going on with the Merlin or in an effort to keep things simple the writer confused anybody who knows about engines.
The Merlin XX only had one blower. There was a two speed drive system to turn the impeller instead of the single speed drive system but there was only one "blower".
I am not saying the two speed drive system was easy to produce, however it was the same drive system that was being produced for the Merlin X engine.
The shadow factories tended to specialize in engines using the single speed drive or the two speed drive. There may have been a difference in the block/crankcase casting. Crew could build both and the short production runs of special engines were made at Crew.
Something is also a bit off with the description of the Merlin 45 offering a 2000ft increase in ceiling. Again a bit simplistic.
The Merlin XII already offered a bit higher ceiling than the Merlin III.
The Merlin XX offerd the most ceiling of the engines available in 1940 and early 1941.
The Merlin 45 was pretty much a Merlin XII fitted with a supercharger (blower) that copied the supercharger used on the Merlin XX. The Merlin 45 used the same single speed drive that the Merlin XII used.
The supercharger used a slightly lower gear ratio and turned the impeller a bit slower than the "high" gear of the Merlin XX and had a slightly lower ceiling.
Mr. Hives was quite correct when he said the Merlin 45 would not affect Merlin XX production as they were going to stick a Merlin XX "blower" on a Merlin XII engine. In fact it may have been only the supercharger front cover and inlet on the existing supercharger.

Tomo types faster than me.

 

[wuzak]

IIRC, the Spitfire III's first flight was with a Merlin X, not XX.

For the Mk III there were changes to the radiator system and to the undercarriage, the tail wheel being retractable, and the main gear fully enclosed.

These changes would cause a significant delay to production during the switch over.

 

[tomo pauk]

IIRC, the Spitfire III's first flight was with a Merlin X, not XX.

One can get a lot of new gray hair when reading the Spitfire III entry in the 'Spitfire - the history' book.
We get a lot of how someone felt about this or that, but deducing the date of 1st flight of the Mk.III, what engine it had for that opportunity, what is a projected performance vs. what was achieved, with or without guns, and with what engine - no, no.
A god book, but, boy, does it request 110% of devotion to read.

 

[Shortround6]

There are some 3d illustrations of the tail wheel of the Spitfire and the structure around it on the internet.
It was not difficult to really make a retracting tail wheel as in knowing how to it.
But it was going to require a lot of different parts.
In fact you would probably want to manufacture the retracting tail wheel models on different assembly lines than the non retracts.

Edit;

I can't find a good picture of the retractable unit but when you fasten things through or attached to vertical fin frame work there is a lot more involved than sticking a hinge on the tail wheel post and fitting a couple of doors

 

[Geoffrey Sinclair]

I was using this:

So Spitfire Mark V used 4 bladed propellers, mark I used Merlin II engines, and the PR IV used Griffon engines, there was no such thing as the PR.III or PR.XI, the conversions are counted as new aircraft, and these figures are considered accurate.

The figures the list actually has right is marks II, IV (if PR.IV), VI, X, XII, XIV, XVI, XVIII (in list a XVII) and XIX, ignoring the conversions that is 9 out of 19. There is a dispute about 1,053 or 1,054 mark XVI. Spitfire prototypes K5054 mark I, N3297 mark III, DP845 mark IV and XII, DP851 mark IV, XX and F.21 and PP139 F.21. 3 mark I airframes, N3296, N3298, N3299 delivered to Castle Bromwich in January 1940 as pattern aircraft, they never flew and are not counted.

Heading for the Hurricane figures you will be delighted to note the ones for British output are reasonable, add the 33 IIA made by Gloster, reduce Hawker IIC to 4,711 and you are there.

As for Canada the Hurricane total was 1,451, made up of 486 mark I, 514 mark II, 1 Dutch version, 400 mark XII and 50 Sea Hurricane I, which became XIIA when fitted with Merlin 29, while 30 of the mark I were converted to mark II before export, no C wings. If the web page says the usual mark X = US Merlin, Packard began building Merlins in August 1941 by which time Canada had built 485 Hurricanes. The British report 419 mark I and 447 mark II arrived without engines, 234 mark II did arrive with Merlin 28, apart from some test flights the engines were used in Lancasters. The sometimes quoted 401 mark XII comes about from the 400 actually built plus the 1 found well post war without any identity plates. The Dutch Hurricane explains the 1 in 1,451, it was originally RAF AM270, a serial also used on a Catalina, so plenty of confusion.

Seafires, the list has the mark 45, 46 and 47 correct.

Spiteful, 16 built but 6 marked "for breakdown", Seafang, 9 produced but 5 marked "for breakdown".

If you have a purported completely-accurate source for Spitfires and Hurricanes, maybe you can share it and also why you think it is exactly accurate.

Highly accurate figures based on a set of primary documents and I did share that list with my first post on Hurricanes.

Because I guarantee I can find another source in print that disagrees with it.

As you did with the Hurricane figures, found two different totals on the web and called it research, not even trying to reconcile the two. One reason I did a long look at the Hurricanes is the apparent vow that no two sources will give exactly the same total production number.

To give a summary, a fuller list is in the original Hurricane post.

RAF Contract cards, tracking deliveries by order, a bit under 7,000 pages of data, on 1930's and 1940's RAF orders. Also included are summary and notes cards of the various orders. Note cards for some orders are missing.

RAF Serial Registers, an entry for most valid serials between K1000 and RZ400, over 9,000 pages.

Quite a number of files from British, US, Canadian and Australian Archives, and Air Force History Units, covering aircraft production from 1935 or earlier to 1949 or later. Published sources like the US War Production Board Canada Section. And so on, then cross checked, including with people who really want to have accurate production figures.

Find a source backed by the above level of documentation and we can talk. As noted this was all given in my first message here.

 

[SaparotRob]

Spitfires are pretty.

 

[Geoffrey Sinclair]

From AVIA 6/10393 R.A.E. Technical note Aero 1273 (Flight) September 1943. Note on speeds of production Spitfires (Marks I, V and IX) by P.A. Hufton M.Sc., and Wm. Stewart B.Sc., September 1943. Four Spitfires were used to test the effect on top speed of the quality of finish and variations in the external equipment of Spitfires, these results were then compared with test results of standard Spitfires. "it is of course impossible to consider our ideal Spitfire in condition (b) (ideal equipment, smooth finish, well fitting cowling) as being a combat aeroplane."

Ideal conditions and corrections for variations. Calculated speed change in mph at 360 mph by variation

Equipment	Ideal condition	Variation	Speed change mph
Exhausts	Multi Ejectors	Original Mk I	5.25​
Exhausts	Multi Ejectors	Triple ejectors with fishtails	7.75​
Exhausts	Multi Ejectors	fishtails and gun heating.	9​
Air intake	No Snowguard	Snowguard fitted	8.5​
Air intake	No Stoneguard	Stoneguard fitted	7.5​
Windscreen	Conical	Internal bullet proof	4​
Windscreen	Conical	External bullet proof	7.75​
Rear View Mirror	None	Faired Mirror	3.5​
Rear View Mirror	None	Unfaired Mirror	6.75​
Radio Mast	None	Standard type	1.5​
Radio Mast	None	Whip type	0.75​
Armament	No cannon projection	2 Cannon	6.25​
Armament	No cannon projection	2 Cannon, 2 cannon stubs	8.5​
Cannon wing bulges	None	Small bulges	0.5​
Cannon wing bulges	None	Large bulges	1.5​
Ejector Chutes	Flush with surface	Projecting from surface	1.25​

Changes to mark V EN946, modified at R.A.E.

Equipment	From	To	gain mph
Exhausts	Triple ejectors with fishtails	Multi Ejectors	7.75​
Air intake	External Snowguard	Removed	8.5​
Rear View Mirror	Rectangular unfaired	Circular faired	3.25​
Radio Mast	Standard type	Whip type	0.75​
Ejector Chutes	Projecting	Cut flush	1.25​
Finish	Standard	Improved	8.5​

Total speed gain expected 30 mph, measured 30 mph, 358 to 388 mph.

Top Speeds mph	As tested	Ideal	Ideal plus improved finish
Prototype Mark I	367​	383​	383​
Production Mark I	357.7​	378.7​	383​
Early mark V	371.5​	405.3​	407​
Late mark V	356.3​	395.8​	407​
EN946 (Mark V)	388​	407​	407​
Prototype Mark IX	414​	438​	445​
Production Mark IX	403.7​	436.3​	445​

Standard Spitfires performance reports used
Prototype K9793, Mark I N3171, X4257, K9787, Mark V K9788, N3053, X4922, W3134, AA878, AA937, AB873, EF644, EN946 (original and modified), Mark IX N3297, BF274, JL227, EN498

References
A. & A.E.E. report 692, various parts.
Improvement in performance of Spitfire EN946, R.A.E. Technical note Aero 1217 (Flight) June 1943
Comparison of three production Spitfires, R.A.E. Technical note Aero 1246 (Flight) July 1943

 

[MikeMeech]

There are some 3d illustrations of the tail wheel of the Spitfire and the structure around it on the internet.
It was not difficult to really make a retracting tail wheel as in knowing how to it.
But it was going to require a lot of different parts.
In fact you would probably want to manufacture the retracting tail wheel models on different assembly lines than the non retracts.

Edit;
View attachment 662509
View attachment 662510

I can't find a good picture of the retractable unit but when you fasten things through or attached to vertical fin frame work there is a lot more involved than sticking a hinge on the tail wheel post and fitting a couple of doors

Hi

Many marks of Spitfire had retractable tail wheels, an official drawing of the Mk. VIII tail wheel below:

Mike

 

[PAT303]

Cunliffe Owen was a major sub-contractor who was later brought in as a second source for Seafire production in 1943.

From what I have read they were the prized models as they where built to the highest standard.

 

[Shortround6]

Many marks of Spitfire had retractable tail wheels, an official drawing of the Mk. VIII tail wheel below:

Thank you.

I know some of them had them.
Trying to figure out how it was to change over production.
Or perhaps better said why it was that one or more factories kept the older style landing gear.

 

[pbehn]

Thank you.

I know some of them had them.
Trying to figure out how it was to change over production.
Or perhaps better said why it was that one or more factories kept the older style landing gear.

I maybe wrong but I think it started with a fuselage which were all the same to start with. When the Mk III was started in development that gave rise to the later Mk VII and VIII but basically a fuselage was a fuselage, what it was kitted out with changed, if it absolutely needed a different tail it got one like with the MK XIV but if a new tail was better but the old tail would do, then the fuselages with old tails were completed and the new ones introduced later. Same with stuff like a retractable tail wheel. As I understand it they were fitted to new production but many fuselages had been made without them. Taking out a fixed wheel and putting in a retractable one just means less Spitfires.

 

[PAT303]

Retractable tail wheels and closed undercarriage came out in 1940 with the MkIII which later became the MkVIII through too MkXIV models.

 

[wuzak]

So Spitfire Mark V used 4 bladed propellers, mark I used Merlin II engines, and the PR IV used Griffon engines, there was no such thing as the PR.III or PR.XI, the conversions are counted as new aircraft, and these figures are considered accurate.

The Spitfire V had 3 blade prop.
The Mk.IV was powered by a Griffon, but was redesignated Mk.XX. Which was the, essentially, the prototype for the XII.
The PR.I Type C was redesignated PR.III and used Merlin.
The PR.I Type D was redesignated PR.IV and used Merlin. The Type D/PR.IV was not a converted fighter airframe and featured the leading edge wing tanks.
The PR.XI was an unpressurised PR version of the VIII. The PR.X was the pressurised version.