Low level Spitfire V vs late war German Fighters

[CobberKane]

The Spitfire V is generally held to have been the equal of the contemporaneous Bf109F, but was outclassed when the Fw190 arrived over Europe. The Spitfire IX eventually arrived to restore parity from 1943, yet large numbers of Spit Vs remained in service up to and after D-Day. Apparently these fighters were optimized for low level performance, with smaller superchargers, clipped wings and the like; how did they stack up against later Fw190s and Bf109Gs they would have met in this role?

 

[Jabberwocky]

The Spitfire V is generally held to have been the equal of the contemporaneous Bf109F, but was outclassed when the Fw190 arrived over Europe.

I'd consider the Spitfire Mk V generally outclassed by the 109F, but the difference was only marginal. With the FW 190, the difference was... significant.

The Spitfire IX eventually arrived to restore parity from 1943

Spitfire F Mk IX entered combat in July 1942.
LF Mk IX, with Merlin 63, 63A or 66 entered service towards the end of 1942/early 1943, depending on engine.

yet large numbers of Spit Vs remained in service up to and after D-Day. Apparently these fighters were optimized for low level performance, with smaller superchargers, clipped wings and the like; how did they stack up against later Fw190s and Bf109Gs they would have met in this role?

The LF MK Vs, known as 'clipped, cropped and clapped' (clipped wings, cropped superchargers and generally clapped out), were gradually introduced through 1942 and 1943, along with higher boost for more speed/climb at low levels. Clipped wings is not a universal sign that a Spitfire is a 'LF' version though. Plenty of LF aircraft, maybe even the majority, were operated with full span wings.

HoHun and others did some good work on the increased power levels of the Merlin 40-series engines in 2009, on this very forum:

29.04.1941 - Spitfire V X.4922: Merlin 45 @ 3000 rpm/+9 lbs all-out level, 2850 rpm/+9 lbs climb, increased to 3000 rpm above ca. 25000 ft
18.06.1941 - Spitfire VB W.3134: Merlin 45 @ 3000 rpm/+9 lbs all-out level, 2850 rpm/+9 lbs climb, increased to 3000 rpm above ca. 25000 ft
xx.01.1942 Merlin 45 type test +16lbs boost. (The Merlin 100 series. RR Heritage Trust).
03.01.1942 - Ministry of Aircraft Production mentions +12 lbs and +15 lbs boosts
08.03.1942 - Spitfire Vc AA.873: Merlin 45 @ 3000 rpm/+9 lbs all-out level, 2850 rpm/+9 lbs climb, increased to 3000 rpm above ca. 20000 ft
30.06.1942 - No. 129 sqn ORB, speed tests at +16lbs boost.
29.07.1942 - R.D.T.3. R.D.E.2. R.T.P.7 Increased Rating for Merlin Engines. Approval 3,000rpm +16lbs boost Merlin 45,46 and 47 engines, operational units of Fighter Command. Previously only applicable to Seafire aircraft and for special applications. 3 minutes duration.
xx.08.1942 - Air Ministry issues memorandum declaring conversion to +16 lbs is currently done
25.11.1942 - Spitfire VC AA.878: Merlin 45 @ 3000 rpm/+16 lbs climb and level
27.01.1943 - Spitfire VB W.3322: Merlin 45 @ 3000 rpm/+9 lbs all-out level, 2850 rpm/+9 lbs climb, increased to 3000 rpm above ca. 20000 ft, 3000 rpm/+12 lbs take-off
03.02.1943 - 1 Sqn (Spitfire V tropicalized and Aboukir filter) clipped wings and +18lbs boost. SB.45457 Performance improvements on Spitfire F Mark V.
12.02.1943 - RAAF clears Merlin 46 and 47 for use of +12 lbs
25.05.1943 - Spitfire VB W.3228: cropped Merlin 50 @ 3000 rpm/+18 lbs climb and level

Comparing a 1941 F Mk Vb with a Merlin 45 at +9 lbs with a LF Mk Vc in 1943 with a Merlin 50 at +18 lbs, the later aircraft is 40-45 mph faster at sea level up to 6000 ft. From there the speed advantage drops. At 8000 ft, speed advantage is around 30 mph. At 10,000 ft the advantage is down to just under 20. At 14,000 ft, the advantage disappears completely.

The LF Mk V will climb about 1500 ft/min faster at sea level, with the climb rate advantage disappearing by about 14,000 ft again.

However, this does somewhat understate the performance of Mk Vs equipped with the standard Merlin 45 which was progressively permitted at higher and higher outputs.

With a Merlin 45 at +16, the standard F Mk V only has a 10-15 mph speed disadvantage and a 800-1000 ft/min climb disadvantage. Or, to put it another way, the standard Mk V was 30 mph faster at low level in 1943 than it was in 1941.

As to how they stacked up against the FW 190/ 109Gs of later periods?

The FW 190 was certainly faster at low altitudes, even against the highly boosted LF Mk Vs. The Spitfire did have a climb advantage though. The clipped wings did improve roll rate, although the aircraft was still not as good in the rolling plane as the FW 190.

There is some disagreement in RAF period literature about how big the improvement was. Some sources point to only marginal improvement or major improvement only on aircraft that previously had poor aileron control. Other sources point to the clipping having a major improvement on both roll rate and roll initiation/alieron responsiveness. The differences are enough that either side can back up their claims with evidence and a nice, toasty forum flame war of about 60-80 pages erupts.

 

[CobberKane]

Thanks Jabberwocky, very informative reply. My date of 1943 for the Spit IX was meant as a rough indication of when the RAF regained parity withthe LF and it's Fw190s rather than a statement of when the IX was introduced, sorry.
Your figures would seem to indicate that the Spit V in its modified forms still represented a dangerous opponent to the Fw190 at low altitudes, closing the gap in speed and roll rate while holding the advantage in climb and, preumably, turn rate. The Spit V LF seems to have been much the kind of fighter the USSR was producing at the same time.
One thing I have read is that the introduction of the IX in 1942 had an effect beyond it's initial numbers - LW pilots quickly became much more cautious of attacking spitfires of all kinds, being unsure of whether they were the new and much more potent model.

 

[fastmongrel]

I presume most of the MkVs were army co operation aircraft by late 43. In which case they probably had enough performance to stay out of trouble but not enough to risk getting into it by chasing 190s.

 

[davebender]

Why did Britain build so many Spitfire Vs rather then converting production entirely over to Spitfire IX during fall of 1942?

 

[Jabberwocky]

Why did Britain build so many Spitfire Vs rather then converting production entirely over to Spitfire IX during fall of 1942?

Because Melin 61/63/66 production could only go so fast and the Mk IX, like the Mk V before it, was considered an interim type until the Mk VIII and the Griffon Spitfire (what would become the Mk XII and the Mk XIV) could enter production.

Spitfire IX (Merlin 61) production by month for 1942 was

June - 19
July - 50
Aug - 63
Sep - 69
Oct - 81
Nov - 72
Dec - 62
Total: 416

There were also some F Mk IX with Merlin 63 deliveries in November and December, but no more than about 15 or 20 by the end of the year. The first LF Mk IXs with Merlin 63As were produced around the same period and delivered in early 1943.

Mk VII, Mk VIII and PR Mk XI production ramped up slowly through the final months of 1942.

There were only around 730 Merlin 61 engines built, with production pretty much being phased out by March 1943. After that the more powerful Merlin 63 took over, with another 1324 produced over the next 14 months (as well as 140-odd Merlin 63As). The Merlin 66 engine comes into production a month or two later.

 

[davebender]

Why not switch to Spitfire IX airframe during fall 1942? Power them with Merlin 45 engines initially. They would get Merlin 61 engine when it becomes available.

Similiar to what Germany did with Me-109F. Early Me-109F airframes were powered by DB601N engine until DB601E engine was available.

 

[Rick65]

As I understand it initially the IX was an interim solution using the V airframe with minimum modifications to accept the two stage 61 engine.
Later IXs incorporated features from the VIII (intended to be the definitive 61 engined model) such as the pointed tailfin and the IX was so successful that the VIIIs became less relevant than anticipated and planned.
The number of IXs available was thus limited by the availability of engines, not by the airframe.
Is this a simplification?

 

[Jabberwocky]

Why not switch to Spitfire IX airframe during fall 1942? Power them with Merlin 45 engines initially. They would get Merlin 61 engine when it becomes available.

You've got things absolutely backwards there.

There was no true "Spitfire IX airframe". The early Spitfire IXs (first 100 or so) were just Mk Vcs converted to a Merlin 61 instead of the Merlin 45.

Detail improvement were introduced through the production run (literally in their hundreds), but the actual airframe was fundamentally no different from the Mk Vc, unlike that of the Mk VII/VIII which was much revised internally and in the control arrangements. The production jigs for the Mk V were changed for the Mk IX, but the differences are minor, mostly to accomodate the nose, which was nine inches longer.

 

[Edgar Brooks]

Why did Britain build so many Spitfire Vs rather then converting production entirely over to Spitfire IX during fall of 1942?

The V was needed in the Middle East, because the IX didn't have a tropical filter, and that didn't arrive until November 1943; Eisenhower asked for the IX, for the invasion of North Africa, but was told he couldn't have them, due to the lack of the filter.

Why not switch to Spitfire IX airframe during fall 1942? Power them with Merlin 45 engines initially. They would get Merlin 61 engine when it becomes available.

We did; it was called the Spitfire V. The first 294 "Mk.IX" airframes consisted of one Mk.I conversion, one Mk.III conversion, with the rest converted from Mk,V airframes.

 

[vinnye]

Did the clipped wing versions have a better roll rate compard to the normal winged versions?
The reason why I ask - is that I recently saw an inteview with one of the test pilots (may have been Quill) said that the only spitfires he did not like to fly were the HF versions with wing tip extensions as they slowed the roll rate down.

 

[CobberKane]

Why did Britain build so many Spitfire Vs rather then converting production entirely over to Spitfire IX during fall of 1942?

I think this has been answered, there were plenty of airframes around but not enough of the new merlins. Remember, the IX was basically a V with an updated engine. possibly had the Fw190 not appeared and completely outclassed the Spit V the IX would never have happened, and the next flavour of Spitfire would have been the VIII, as originally envisaged (hence the non-sequential model designations.)As it happened the IX was better than anyone expected it to be and largely largely 'replaced' the VIII before it even appeared.

 

[Juha]

...The V was needed in the Middle East, because the IX didn't have a tropical filter, and that didn't arrive until November 1943; Eisenhower asked for the IX, for the invasion of North Africa, but was told he couldn't have them, due to the lack of the filter...

Anyway some sqns equipped with Mk IXs participated the Tunisia Campaign. At least thefollowing, there might have been others but these came first in my mind.
81 Sqn began receive Mk IXs in Jan 43
92 Sqn began receive them in Apr 43
145 Sqn began receive them in Mar 43, to my understanding these might well have been the IXCs of the Polish Fighting Team, which was attached to 145 Sqn and was equipped with Mk IXCs in late March 43.

Juha

 

[Mike Williams]

Anyway some sqns equipped with Mk IXs participated the Tunisia Campaign. At least thefollowing, there might have been others but these came first in my mind.
81 Sqn began receive Mk IXs in Jan 43
92 Sqn began receive them in Apr 43
145 Sqn began receive them in Mar 43, to my understanding these might well have been the IXCs of the Polish Fighting Team, which was attached to 145 Sqn and was equipped with Mk IXCs in late March 43.

Juha

Hi Juha,

Please allow me to add to your list of RAF units converting to Spitfire IXs in North Africa early in 1943, 72 Squadron which converted in February. You might remember this passage from 72 Squadron S/L Bobby Oxsbring's book Spitfire Command where he writes about converting to Spitfire IXs, the use of improvised air intake filters and an amusing anecdote regarding synchronizing the supercharger gear changeover. It comes to mind that the 31st and 52nd US fighter Groups also converted to Spitfire IXs during the North African campaign. Incidentally, there are some interesting scans of 52nd FG Spitfire IX Combat Reports Here.

By the time of the invasion of Sicily in July 1943, many Malta/MTO based Spitfire units were equipped with Spitfire IXs such as 4 SAAF, 72, 81, 87, 92, 93, 111, 123, 126, 145, 154, 185, 232, 242, 243, 249, 1435, 31st FG (307th, 308th, 309th ) and 52nd FG (2nd, 4th 5th) (listing not intended to be all inclusive).

 

[Vincenzo]

81st used also the V until november '43
92nd used also the V until september '43
145th used also the V until september 43
72 used also the V from june '43 to january '44
87th used also the V until august '44
93rd used also the V until february '44
111th used also the V until january '44
123rd used the IX only in july/august '43, also the V until september '43 and the Hurricane II until september '44
126th used also the V until march '44
145th used also the V until september '43
154th used also the V until february '44
185th used also the V until september '44
232nd used also the V until february '44
242nd used also the V until february '44
243rd as above
249th used also the V until september '44
1435th used also the V until november '43 and again from may '44 to september '44-

 

[Tante Ju]

Its seems the Mark IXs use in the MTO was sporadric and intermittent with units, which often used them in a mixed fashion with Mark Vs.

Does anyone know the number of Mark V/IX with units in the MTO in 1943?

 

[Juha]

Thanks Mike
I should have remembered 72 Sqn, it wasn't so many years ago when I read Oxsbring's memoirs.

Hello Vincenzo
Yes it seems that all those early Spit IX MTO sqns but 72 used Mk Vs and Mk IXs side by side until they were re-equipped with Mk VIIIs (81 in FE) or LF IXs later on and even 72 got some VCs in June 43.

Juha

 

[Mike Williams]

 

[Juha]

Hello Mike
Thanks a lot for the ORB pages. My info was from Jefford'd RAF Sqns. It seems that at least 81 and 72 got the full complemet of Mk IXs initially. And it was interesting to found out that it seems that in MTO the normal complement of a fighter sqn was still 16 I.E.(initial equipment) and 8 I.R. (immediate reserve) as had been in 1940.

Juha

 

[Vincenzo]

Juha can you cheek on the book the data for Spit V, i've doubt that november '43 is a mistyped for november '42... oops for the 81st Squadron
reading the history the squadron became inoperative in november '42 so it's strange that had fighters...