Special High Altitude Spitfires

[Dave Swindell]

52 minutes ago, Graham Boak said:

Both well worth buying and reading anyway.

The Wingleader book is on my birthday wishlist, so should hopefully arrive next month! Less interested in the Stratus book as my focus is RAF/FAA centred..

[Graham Boak]

The Wingleader book doesn't have anything on the M46: there is to be another dealing predominantly with overseas aircraft so I expect that much of the "missing" stuff on the Mk.Vc will be in there.  It does point out (as does the Stratus) that some early Mk.Vs retained the Coffman blister, but this is just using up residual panels.  A photo of Mk.VI AB534, which has a slightly larger blister in a very similar place, perhaps slightly further forward.  As this is covering where the vacuum pump is, could it indicate a modification to take air from this to pressurise the fuel tanks on the Mk.VI.  As this blister isn't seen on Mk.IXs etc this cannot be the final mod, and may be something else altogether - but what?

 

The Stratus books are an excellent source of high quality photographs of Spitfires, despite their restriction to examples in PAF hands.  As these aircraft were used other than by the PAF, and lack PAF-specific modifications (apart from some rear-view mirrors), there's still a lot for the Spitfire (and indeed Fighter Command) enthusiast to enjoy.  However I wouldn't expect to see a reference to the Merlin 46 in there, so I'm a little baffled as to just what I was reading.  It might be best to check photos of RAAF aircraft for this mod - or not!

[Geoffrey Sinclair]

5 hours ago, M20gull said:

BR234 - the database suggests that the plane has a Merlin 61 fitted.  As this one was destined for Australia this modification, if correct, must have been made in Africa, presumably at 103 MU.  I cannot see why you would ship a Merlin 61 to Aboukir with its associated spares.  Why not just ship a IX?   I guess there is no way of knowing the truth here.

Then again, from the Ministry of Aircraft Production Monthly Statistical Bulletins.  Building up stocks of spare engines before the aircraft arrived.

 

February 1943 report Merlin 61 Allocated for Shipment Abroad, 12 in September 1942, 6 in October, 10 in November, 17 in December, 12 in January 1943, total 57.  Note the word Allocated.
March 1943, column now titled Merlin 61, 63, same numbers as February, plus 6 in March.  So now a total of 63 allocated.
April 1943 was an abbreviated report, no export tables.
May 1943 Engines shipped or awaiting shipment abroad 1 January 1941 to 31 May 1943, sixty four Merlin 61, 63.

 

Merln 45, 46, 47 allocations for shipment abroad began in November 1941, with 9, then 20 in December.  Total for 1 January 1941 to 31 May 1943 was 378 Merlin 46, 46, 50, 55, 56 and 2 Merlin 47 shipped or awaiting shipment.

 

Until the October 1942 report the Spitfire export tables do not give mark number information.  Ignoring earlier marks,
25 Spitfire, mark unspecified, exported in five weeks ended 2 October 1942, also note 6 mark VI during this period
14 Spitfire, mark unspecified, exported in four weeks ended 30 October 1942
No mark IX Spitfire exported in five weeks ended 4 December 1942.
52 Spitfire IX, exported in four weeks ended 1 January 1943
38 Spitfire IX, exported in four weeks ended 29 January 1943

 

I think December 1942 did see the first mark IX exports.

 

[Graham Boak]

The 23rd March saw the first allocation of Mk.IXs to 92 and 145 Squadron in the Western Desert Air Force.  An order of battle for 24th March also has them with 72 and 81 Sq in Tunisia.  Given time for assembly, delivery etc these dates appear compatible.  Source Vic Flintham's Call to Arms, Hikoki 2020.

[M20gull]

 I should have included that the reason for my doubt on BR234 is that it is listed in Shores' Air War in The Mediterranean as the plane lost on 6-9-42 in the successful sortie by Eric Genders. Actually it is given as BR243 but that is just below the claim for the Ju 86 which is against BR234. The Strike off charge date for BR234 is 13-9-42

Edited February 17, 2021 by M20gull

[M20gull]

With not much more to add on BR234 or BP985 I thought I would address the role of the Mk VIs.  I will come back to BP985 later though.  BR114 I will discuss in more detail too.

 

In the text Morgan and Shacklady gives a list of four VIs sent "to reinforce BP985 high alt FV against Ju86P-2 sorties": BS106, BS124, BS134, BS149.  However the serial numbers section includes the same reference for BS133 which is usually included in this list, sometimes with an oblique reference to another unidentified one.  These VIs arrive in Takoradi on the MV Ripley on 3-10-42.  (This was Ripley's last contribution - having visited other ports in West Africa she was sunk on 12-12-42 by a U-boat in the South Atlantic as she returned to the UK via Trinidad, all 41 lives were saved for which Gordon Lynton Hargreaves, the fifth engineer, received an MBE).

 

Also on the Ripley was a PRIV (not relevant to this story) and one other Spitfire BS427.  This is recorded in Shacklady as a VII but is on the production database as a VI.  Maybe this is a sixth one to add to the list?

 

Initially I thought there were only the photos of  BS124 ('A') but thanks to @corto's post we have a shot of 'C' as well, which it seems reasonable to assume is the one in the back of the Joe Willis photo .[edit: originally thought to be BS133 but later photos show this to be BS134]

 

Mods for the VIs, which were intended as Markers, are fewer than for the Vs:

• Removal of the machine guns
• Vokes filter

I've seen different intepretations of the colour scheme.  I painted my BS124 standard desert colours presuming they were applied before shipping (this is how DK Decals specify it in their High Altitude Spitifres set) and would not change that.  You may feel differently.

 

The additional weight of the pressurisation did not offer any advantage over the Vs so the VIs were quickly discarded.  It is suggested that the planes were sent to 680 squadron for PRU duties.  BS124 has no entry on the database after a flying accident on 12-12-42.

 

680 was formed on 1-2-43 from 'A' flight of 2 PRU.  2 PRU Operation Record Book is not digitised but 680's is.  They receive two VIs in February (corrected from March) and one in March (Corrected from April).  So far I have found entries for:

 

BS106 - two communication flights in July from Cyprus, no ops

BS133 - one op to Crete on 5-5-43, total flying time that day 9.25 hours

BS149 - force landed cat II 15-4-43 with engine trouble, no ops

 

I had assumed that a high-flying PRU spitfire would have downward facing cameras but BS106 is recorded as "FR with F.8 oblique camera". I would expect them to be repainted as well

 

Update: BS106 is the last one with 680, returning to 103MU on 2.8.43.  

 

BS134 and BS427 could presumably have been kept by 103 MU for spares or cannibalised to improve the Vs. They are not struck off charge until 1946 and 1944 respectively so they were somewhere!

 

There are no photos of them in their PRU role so any model would be speculative (which I am not above doing).  I can see a Bosun Blue FR VI with machine guns deleted, oblique camera, Vokes filter, 90 gallon slipper tank, pale blue roundels, grey serial BS133, no fin flash.

 

 

 

Edited February 27, 2021 by M20gull
Attributing ‘C’ to BS134

[Geoffrey Sinclair]

Delivery Logs, entries marked Takoradi, 8 September 1942
Mark VI
BS106 (TOC 5 July 1942, SOC 26 April 1945)
BS124 (TOC 26 July 1942, SOC 1 January 1947)
BS133 (TOC 13 August 1942, SOC 26 April 1945)
BS134 (SOC 18 August 1942, 29 March 1946)
BS149 (TOC 23 August 1942, Cat E ? Feb ?, SOC 26 April 1945)

 

mark VII

BS427 (TOC 29 August 1942, Cat E 25 May 1944, SOC 31 May 1945)

 

Contract 19713/39 for 140 mark VII, total deliveries 141, starting at BS121 (AB450 was a converted mark V).  Merlin 64 engines.  The Ministry of Aircraft Production total is 139.  The contract card notes two non effectives, EN474 to the US Army New York, MD176 CRD, not in ledger.  The MAP figures tend to ignore aircraft allocated to CRD.  (Scan 3/1173 Contract cards)

 

However it appears BS253 and BS427 were both mark VI, but I have not sighted the individual aircraft cards to confirm this.  One complication is the 16 mark X were an offset to the mark VII, reducing the mark VII order to 140 from 156, and the mark X were initially recorded as mark VII in the production reports (11 in April and 5 in May 1944) mark VII production ended in May 1944.

 

Mark VII official production in 1942 was 2 Sep, 1 Oct, 2 Nov, 2 Dec  Contract card/Taken on Charge dates for first 8 contract card mark VII serials were,

BS121 5 September 1942
BS142 17 September 1942
BS229 2 November 1942
BS253 22 October 1942
BS427 25 August 1942, so the first production mark VII if correct.
EN178 4 December 1942
EN192 1 December 1942
EN285 29 December 1942

or 1 Aug, 2 Sep, 1 Oct, 1 Nov, 3 Dec.  If you take out BS427 but leave in BS253 it is quite a neat match.  Mark VI production August to November 1942 was 6, 3, 8 and 2 respectively, however in October 1942 the cumulative mark VI production total increases by 9, but no record of the extra aircraft's serial number.

 

Contract card Mark VII serials, BS121, BS142, BS229, BS253, BS427, EN178, EN192, EN285, EN297, EN310, EN457, EN465, EN470, EN474, EN477, EN494 to EN497, EN499, EN505, EN506, EN509, EN511, EN512, MB761 to MB769, MB806, MB808, MB820 to MB828, MB883 to MB887, MB912 to MB916, MB929 to MB935, MD100 to MD146 and MD159 to MD190.

 

Air 20/1871 The RAF census for end June 1944 says 100 mark VI ordered, 99 delivered, 3 other Spitfires converted to VI, total 102.  Mark VII were 156 ordered, 153 delivered, 14 converted from VII, total 139 (also 16 conversions to mark X).  It seems since 16 mark X were initially reported as mark VII the RAF considers all mark X as conversions.
Supermarine Production ledger says 99 VI and 140 VII, probably ignoring prototypes
MAP Official total 100 VI and 139 VII.  (Seems to be counting X4942, the prototype, as a VI, not a converted V, but omitting AB450 the VII prototype)
Spitfires website http://www.airhistory.org.uk/spitfire/home.html says 100 VI and 140 VII. (Counting X4942, BS253 and BS427 as VI and AB450 the VII prototype)
Supermarine Spitfire by Peter Moss says 97 VI and 141 VII (BS253 and BS427 as mark VII and ignoring prototypes)
Morgan and Shacklady say 97 VI and 141 VII (BS253 and BS427 as mark VII and ignoring prototypes)

 

The RAF census says as of end February 1943 there were 6 mark VI in the Mediterranean, which supports BS427 as a mark VI.  As of end June 1944 there were 5 mark VI in the Mediterranean, after 1 "overseas" loss, there was also 1 mark VII in the USA, no mark VII lost overseas.

[Denford]

On 2/16/2021 at 6:54 PM, M20gull said:

@Dave Swindell

• Oil tank - cannot believe I wrote that as I knew the oil tank was standard for the Tropical Vs
• Rudder bar - I don't know any more - it is mentioned in the Aeroplane Spotter article.  I wonder if there is part of the bar that could be removed at the expense of pushing harder or just accepting that for the interceptor role drastic rudder movements were unlikely
• Heating pipe - this is visible in the Aeroplane Spotter article above the exhaust and in this photo.  It made me think that it might be used for additional cockpit heating given the low temperatures at altitude

Per earlier post, heating for the Starboard gun could have come from the radiator (standard arrangement?).  However on the Port side there was only the oil cooler so maybe a heating pipe that side only.

[Graham Boak]

This assumes that the exhaust bleed was for heating the guns rather than pressurising the fuel tank to prevent a vacuum forming and restricting flow to the engine.

[Dave Swindell]

10 minutes ago, Denford said:

Per earlier post, heating for the Starboard gun could have come from the radiator (standard arrangement?).  However on the Port side there was only the oil cooler so maybe a heating pipe that side only.

Negative, the radiator heating duct fed both sides.

It was introduced on the A wing to heat all 8 mg's, and initially was more effective on the inner guns, and especially on the stbd side ( or another way it was less effective on the outboard guns, especially on the port side).

Wing tip extractor vents were introduced to improve the warm air flow to the outer guns, if you check photo's you will note that the port side extractor vent is larger than the stbd one to assist the air flow the further distance across the fuselage.

With the B wing the same heating arrangement was retained, but it was noted that heating was at times insufficient for the much larger cannon bays.

When the C wing was introduced on the Mk V, the heating from the radiator was used just to heat the cannon bays on each side, more heating potentially being required here due to the possibility of fitting 2 x cannon per side. This left the outer mg bays without heating from the radiators, which led to the introduction of the the exhaust heating intensifier tubes, which led air through a pipe passing inside the exhaust manifolds, then into the engine bay and down to the wing leading edges, out along in front of the main spars and back into the outer machine gun bays. The port exhaust heated the port bays, and the stbd exhaust heated the stbd bays.

With the introduction of the 60 series Merlins and radiator blocks under each wing the shorter pipe runs and higher radiator heat output permitted gun heating for all guns in each wing to be fed from the radiator on the respective wing. This was applicable to both C and E wings, and the heating air source came form the engine coolant radiators, not the intercooler radiator or oil cooler.

 

18 minutes ago, Graham Boak said:

This assumes that the exhaust bleed was for heating the guns rather than pressurising the fuel tank to prevent a vacuum forming and restricting flow to the engine.

The gun heating wasn't exhaust gas, it was air heated by the exhaust gas as it passed through a tube through the exhaust stacks

The photo's of BR114 show that this system has at least been disconnected and part of the pipework removed as evidenced by the blanking plate on the stbd cowling and the open end of the air heating pipe on the aft end of the port exhaust stack in the photo from aft.

The small bore pipe is visible only on the port side, and is too small to provide the volume of air required to heat guns (or the cockpit), but it's big enough (IMHO) to supply a small volume of exhaust gas to maintain an above ambient atmospheric pressure in the fuel tanks, which would help prevent the fuel boiling at altitude. 

I've no direct evidence that this is actually what the pipe is, rather it's an educated guess given the problems being faced and possible solutions. If anyone else has plausible explanations for the pipe, I'd welcome hearing them, or if there's any evidence of other use I'm happy to revise my opinion.

[M20gull]

I thought the discussion on pressurised fuel tanks sounded familiar. Over on Vol 2 all the Spitfire questions there was chat in relation to a vent pipe. The tropical Vs should already have a pressurised fuel tank, maybe it needed a bit of a boost.

[M20gull]

@Geoffrey Sinclair thank you for the detailed answer.  Who knew it would be so difficult to count a couple of hundred aircraft?!

[Dave Swindell]

1 hour ago, M20gull said:

I thought the discussion on pressurised fuel tanks sounded familiar. Over on Vol 2 all the Spitfire questions there was chat in relation to a vent pipe. The tropical Vs should already have a pressurised fuel tank, maybe it needed a bit of a boost.

I was aware of the pressurisation system, but had somehow associated it with just the HF Spitfires, rather than the Trops. As the Trop modifications were introduced on the Vb's then as you say BR114 should have had this fitted - I had assumed it hadn't yet been introduced.

The standard fuel pressurisation system uses the discharge from the engine driven vacuum pump as a pressure source, I can't see how the exhaust pressure system that I've associated with this additional pipe could be used to boost the output from the vacuum pump. However, the vacuum pump is drawing power from the engine for its operation, and increasing the backpressure that it operates against (which would happen if used to pressurise the fuel tanks) would increase this engine power loss. There appears to be a concerted effort to extract as much power from the engine as possible, especially at altitude, which is where the pressurisation is required. Disconnecting  the pressurisation pipe from the outlet of the vacuum pump and leading it to the port exhaust stubs would reduce the engine power loss and provide a source of pressurisation. The fact that they experienced problems with fuel boiling might indicate that this solution (if in fact this is what it is) was less effective than hoped for.

[Denford]

Recent postings seem to indicate that heating tubing to the two guns was removed: ie they were unnecessary.

It’s my belief that most gun seizures and stoppages were caused by ice either ‘joining’ parts so they couldn’t move/flex or ‘enlarging’ them eg links, ammunition so they couldn’t pass through various apertures.  In the UK water water could be present at any time in the form of condensation and/or rainwater collection in aircraft parked outside.  In the desert: well need I say more!

There’s an oft repeated tale of combat between a Ju86 and Spitfire Vll high over the UK.  The battle ended when one of the Spitfire’s cannon seized \ stopped firing and both particpants survived to be ‘re-united’ after the war!

I’ve seen no record of comments on the Spitfire after landing, but can imagine head shaking and muttering ‘We never had this problem chasing 86’s over Egypt….’

[Graham Boak]

However, they did have this problem in the skies over Darwin, where the Japanese bombers were flying at 29,000ft.  And indeed elsewhere, the Hispano cannon being temperamental at times.

 

However, I've little belief that what was happening in Egypt was closely tracked by the equivalents at home.  Further, I suggest that this story actually belonged to a very early Mk.IX and the first appearances of the Ju.86P (or R) anywhere.  It isn't clear to me that the Mk.VIIs ever encountered the 86, as opposed to other high-flying German recce aircraft.

[M20gull]

A copy of Brian Cull’s Fighters over the Aegean has arrived here today.  Looks a good read from my first skim.

[alt-92]

17 hours ago, Graham Boak said:

I suggest that this story actually belonged to a very early Mk.IX and the first appearances of the Ju.86P (or R) anywhere. 

That would be Galitzine, most likely.

[M20gull]

On 15/02/2021 at 21:23, M20gull said:

A quick aside:

 

Wendel Nelson was reportedly the OC of the High Altitude Flight at 103 MU in Aboukir.  I've ordered copies of the 2009 Flypast magazines that cover his story but there is a hint of it here and details of his final accident here.

 

Update following the arrival of the Flypast magazines.  Nelson was better described as Flight Commander.  Having arrived in the Middle East in September he flew tank-busting with 6 Squadron Hurricanes for a month before being injured.  His recuperation involved high altitude flying with 103 MU including taking a PRIV up to 50,000 feet!  He returned to the USA in early 1943.

 

Having flown night-fighters, tank busters, high altitude intereceptors and PR for the RAF he joined the USAF and lost his life on bomber escort.

[M20gull]

Following Brian Cull's book arriving my suggestion of the external pipes being for cockpit heating is confirmed incorrect; there was no cockpit heating.  It doesn't say what the pipe was for though!

 

The comments from Bing Cross in the book show that the process was incremental as they kept trying more changes, e.g. removing the Brownings and flying with just the cannons before swapping them.

 

 

 

 

[M20gull]

@Geoffrey Sinclair

 

I think your data on the Merlin 61 / Mk IX exports suggests that BR234 can not have had a Merlin 61 fitted if it was the plane lost on 6-9-42 as the first Merlin 61s allocated for shipment abroad were in September 1942.

[Hornet133]

Were they really going to try to fit a Merlin 61 (a Mk.IX engine) to BR234 (a Spitfire Mk.V) ??

 

OK it is possible ala the 78 Rolls Royce converted Mk.V airframes with 60 series engines, but it sounds like a very BIG job for someone other than the original factory or engine makers.

Edited February 19, 2021 by Hornet133

[M20gull]

I am prepared to put it down as a mistake on the cards or a misunderstanding on my part.

[M20gull]

On 16/02/2021 at 21:43, M20gull said:

I think it is BR114 for a number of reasons but it is only speculation. 

Morgan and Shacklady claims that BR114 is named "Irene" and I think that there is a script on the fuel tank cover consistent with that name.

Secondly the production database has a Ops Cat B on 13-9-42, i.e. after the Ju86 claims. This suggests to me that it needed some repair and that may have required a repaint.  That is reinforced in my mind as the later group of photos, which because they include VIs must be November or later, show BR114 in 'b' pattern that should not have been there originally.  These later photos also do not have the "Irene".

I might need to rethink this.  I was looking at some more ORBs for details of another plane when I came across more data for BR114 which might just mean a mistake on the database entry.  601 squadron arrived in Egypt from the UK at the end of June 1942 and started ops on 1 July with Vcs.  BR114 was one of their aircraft and on its 8th op force landed with engine trouble. This was on 13.7.42 which might be the entry on the database instead of 13.9.42

[Graham Boak]

601 actually arrived in Egypt from Malta.  Not from the UK: it had been on Malta for some months since arriving courtesy of the USS Wasp,  but the reduction in air activity had freed it.  However BR114 has no Malta history.

[M20gull]

10 minutes ago, Graham Boak said:

601 actually arrived in Egypt from Malta.  Not from the UK: it had been on Malta for some months since arriving courtesy of the USS Wasp,  but the reduction in air activity had freed it.  However BR114 has no Malta history.

As I worked backwards from September I was expecting to find a transfer from Malta.  The aircraft I was looking for was BR363 which is on Malta Operation Style.  The 601 data on historyofwar does not mention a Malta stay in 1942. The ORB shows that they were on a ship via Freetown and Durban in May and June 1942. I will look further. There is definitely a link to Malta in this period.