Halifax Mk II and V subvariants

[33k in the air]

The Halifax Mk II and V had three subvariants: the Series I, Series I (Special), and Series Ia. Does anyone have any data on the production numbers of each subvariant?

I only have once source on hand which lists such information: Halifax at War by Brian J. Napier (Ian Allan Publishing, 1986). According to the serial number ranges it provides, there were about 1,388 Series I and 589 Series Ia for the Mk II (70% to 30% split), and about 388 Series I and 516 Series Ia for the Mk V (43% to 57% split). It does not make any mention of the number of Series I (Special). However, another reference I have (I forget which) mentions Handley Page itself built 299 Mk II Series Ia, which, looking at the serial number batches, would mean about 1,150 Series I and 827 Series Ia for the Mk II (58% to 42% split).

I'm unclear if the Series I (Special) was only from conversions of Series I aircraft, or if some came out of the factory that way. Photos and illustrations of Series I (Special) aircraft show some with no dorsal turret, some with the two-gun dorsal turret, and some with the four-gun dorsal turret. So alterations and variations for this subvariant seem not uncommon.

Even if the number of Series I (Special) varied due to conversions in different periods, a snapshot of the relative numbers at a specific point in time would still be helpful, particularly as it compared to the other two subvariants.

 

[gruad]

Are you one of the guys working on the Canadian restoration of the Halifax?

I saw something on YouTube about it last night and it was absolutely fantastic.

 

[33k in the air]

No, I'm just someone who gets too deep into details sometimes.

 

[gruad]

I seriously love the Lancaster and Halifax and the S

No, I'm just someone who gets too deep into details sometimes.

terling.

 

[Geoffrey Sinclair]

AVIA 46/112 Halifax Biography. April 1942 complaints about performance mostly about having to fly with bomb bay doors partly open when carrying the bigger bombs. A new design bomb bay doors interfered with H2S operation, so the design was dropped.

August 1942, more complaints about performance. Changes were front turret removed and replaced retrospectively by a metal faring and in production by a perspex nose, the 4 gun mid upper turret and astrodome were lowered. Improved dampers fitted and various drag producing items modified. "These changes were eventually associated with the designation Halifax II Series Ia, though in point of fact this was really applied to a change of radiator which took place at about the same time. First production deliveries of the Series Ia took place in February 1943. Merlin XXs were still fitted…" Also around this time the engines began to be changed from Merlin XX to 22, which would also explain the radiator change. The use of series Ia was due to series II being allocated to a two stage Merlin variant, which was flight tested in April/May 1943.

February 1943, the four gun upper turret starts to be fitted to production aircraft, after a decision made in May 1942. No mention of when the rectangular fins were introduced but I understand it was later and plenty of aircraft were retrofitted.

To obtain 1,388 mark II series I requires all mark II production until sometime in July 1943, for 388 mark V series I requires all mark V production to sometime in August 1943. Assuming the lines all changed over in the same month. If Handley page built 299 mark II series Ia that requires all production from sometime in December 1942.

Assuming for the sake of argument all Mark II and V were series I to end February 1943 and Series Ia thereafter, the split is 994 to 976 mark I, 149 to 755 mark V. Since the mark II was in production until May 1944 and the mark V until July 1944.

A good chance all the Series I special were converted. Unless the form 78 cards say something it is contact the authors and ask where their series information came from time. Or do photograph searches to see if anything can be pinned down. From a quick check of the aircraft cards,

HP II serials, HR660 in December 1942, seems to be the first Merlin 22, some later serials with Merlin XX. The first serial with Ia marked on its card is HR841 in May 1943, then HR845, HR847, HR855, as time goes on more cards are marked Ia

LAP II looks like they begin fitting Merlin 22 with BB329 in March 1943, JN882 the first Ia in July 1943, JN884 no series information, JN885 on seem to be series Ia.

English Electric II were still fitting Merlin XX to end production in October 1943, none of the cards checked were marked Ia.

Fairey V began fitting Merlin 22 with DK235 in June 1943 and it appears to be a clean change over, with DK244 in July the first card marked Ia, but some later cards have no series information.

Rootes V first series Ia LK890 in July 1943, again not all cards marked.

Of the 5 production lines the switch to series Ia was 1 in May 1943, 3 in July, 1 unknown assuming the early series Ia cards are properly annotated. Rather later than the biography states.

 

[33k in the air]

To obtain 1,388 mark II series I requires all mark II production until sometime in July 1943, for 388 mark V series I requires all mark V production to sometime in August 1943. Assuming the lines all changed over in the same month. If Handley page built 299 mark II series Ia that requires all production from sometime in December 1942.

Assuming for the sake of argument all Mark II and V were series I to end February 1943 and Series Ia thereafter, the split is 994 to 976 mark I, 149 to 755 mark V. Since the mark II was in production until May 1944 and the mark V until July 1944.

A good chance all the Series I special were converted. Unless the form 78 cards say something it is contact the authors and ask where their series information came from time. Or do photograph searches to see if anything can be pinned down. From a quick check of the aircraft cards,

HP II serials, HR660 in December 1942, seems to be the first Merlin 22, some later serials with Merlin XX. The first serial with Ia marked on its card is HR841 in May 1943, then HR845, HR847, HR855, as time goes on more cards are marked Ia

LAP II looks like they begin fitting Merlin 22 with BB329 in March 1943, JN882 the first Ia in July 1943, JN884 no series information, JN885 on seem to be series Ia.

English Electric II were still fitting Merlin XX to end production in October 1943, none of the cards checked were marked Ia.

Fairey V began fitting Merlin 22 with DK235 in June 1943 and it appears to be a clean change over, with DK244 in July the first card marked Ia, but some later cards have no series information.

Rootes V first series Ia LK890 in July 1943, again not all cards marked.

Of the 5 production lines the switch to series Ia was 1 in May 1943, 3 in July, 1 unknown assuming the early series Ia cards are properly annotated. Rather later than the biography states.

Below are the tables from Halifax at War which show the mark and series type, serial number block, and construction period, for Mk II and Mk V aircraft. These tables appear on pages 17, 29, 46, 52, 60, and 68, respectively.

From the above, it works out to 1,388 Mk II Series I and 589 Mk II Series Ia. There is one entry for the Mk V (DK223–DK271, 49 aircraft) which doesn't list the series number. Of those with the series number, 339 were Mk V Series I and 516 Mk V Series Ia

To get 299 Mk II Series Ia built by Handley Page, the serials HR654–HR699 and HR711–HR952 would have to be included:

HR654–HR699 (46 aircraft – listed as Series I in the screenshots above)
HR711–HR952 (192 aircraft – listed as Series I in the screenshots above)
HR977–HR988 (12 aircraft – listed as Series Ia in the screenshots above))
HX147—HX225 (49 aircraft – listed as Series Ia in the screenshots above)

46 + 192 + 12 + 49 = 299

I did a spot check of a few of the Form 78 cards, but none showed the series number, just the mark number. I didn't think to check the engines fitted.

 

[Geoffrey Sinclair]

Change over according to Brian Napier, all production lines managed to make the change at the exact end of a serial block. Change over month is when cumulative number total exceeds the number of reported series I

English Electric mark II, series I JB781 to JB794, series Ia JD105 to JD476, number 578, in April 1943

Handley Page mark II, series I HR711 to HR952, series Ia HR977 to HR988, number 554, in August 1943, except form 78 cards have series Ia from at least HR841 in May.

LAP mark II, series I JN682 to JN926, series Ia JN941 to JN978, number 246, in September 1943, except series Ia from at least JN882 in July.

Rootes mark V, series I EB127 to EB276, series Ia LK890 to LK999, number 251, in August 1943, series Ia from at least LK890 in July.

Fairey mark V, series I DK165 to DK207, series unknown DK223 to DK271, series Ia LK626 to LK746, number 102 or 151, in May or August 1943, except series Ia from at least DK244 in July.

First series Ia as per message 5 quick check.

Merlin 22, Derby built 1,486 mid 1942 to end August 1943, Crewe 1,387 October 1942 to end January 1944, Glasgow 2,164 April to end November 1943, Ford 3,593 July 1943 to October 1944, total 8,630.

 

[33k in the air]

When I applied the Halifax at War serial blocks to individualized serial number lists, I did come across a few errors, probably typos/misprints. This was before the Halifax serial numbers thread.

Just to further (muddy?) things, there is this from Handley Page Halifax by Anthony L. Stachiw and Andrew Tattersall (Vanwell Publishing, 2005). These appear on page 18.

Aircraft equipped with this modification [clear perspex nose and four-gun dorsal turret] were designated HP.59 B.Mk II Series Ia, or HP.63 Mk V Series Ia. These also featured low drag nacelles derived from the Bristol Beaufighter Mk IIF which had rectangular Morris block radiators in place of the Galley twin drum radiators as installed in the HP.57 Halifax B.Mk I. The fully modified prototype HP.59 Halifax B.Mk II Series Ia, HR679, first flew at Radlett on 24 December 1942. The aircraft was 10 mph faster than Halifax B.Mk II W7922, even when the latter had its Boulton Paul Type C1 upper turret removed . . .

. . . The first GR.Mk II Series Ia was JP258 and the first B.Met Mk II Series Ia was DG344.

. . . A total of 299 HP.59 Halifax Mk II Series Ia variants were built at Cricklewood, nearly all equipped with Boulton Paul Type A Mk VIII four-gun upper turrets.

Halifax in Action by Jerry Scutts (Squadron/Signal Publications, 1984) on page 27 says this:

The prototype Halifax Mk II Series Ia (HR679) flew from Radlett for the first time on 14 December 1942. 299 were built, all by Handley Page.

I presume the difference in first flight date is a typo/misprint in one of the two books.

 

[33k in the air]

Given the references seem to agree the Mk II and Mk V Series Ia used the Merlin 22 engine, doing a check of the Form 78 cards for the HR654–HR713 serial number block yields the following:

First with Merlin 22 is HR660. The subsequent numbers all have Merlin 22 except for HR668, HR681, HR684, HR697–HR699, and HR711, which list Merlin XX; HR672 engines are unclear; HR678 and HR682 engines not listed; and HR713 lists Merlin 28.

ETA: I just realized I duplicated a serial number block you mentioned in post #5. Bit of brain hiccup on my part.

 

[Geoffrey Sinclair]

The production reports consider all Halifax mark II and V to be bombers, any reconnaissance versions being conversions, the reports also ignore series identification.

Starting in early 1943 a series of changes were made to the standard Halifax II, new radiator which the biography says is the official item which defines a series Ia, plus Merlin 22 plus 4 gun mid upper turret plus a clear nose replacing the front turret. Stachiw and Tattersall note the clear nose and new radiator was fitted to all series Ia then state 299 series Ia from Handley Page *most* of which had the new four gun mid upper turret, meaning the turret did not define series Ia. The definition cannot be Merlin 22 unless English Electric stayed with series I to the end, as they kept fitting Merlin XX.

Conclusion it really is the radiator that defines whether a Halifax II was series I or Ia leading to the possibility some flew as hybrids.

Handley Page built 18 Halifax II in December 1942 and 285 January to October 1943. To obtain 299 serials as per Stachiw and Tattersall requires all the HR block which starts at HR654 plus the 49 HX serials before the change over to mark III. If everything from HR679 onwards was series Ia that gives 274 aircraft. HR654 was delivered to 408 squadron on 21 December 1942.

The aircraft card for HR679 does show it going to the AAEE. The last W serials were delivered in mid December 1942, along with the first HR serials at a time when the line was producing under 1 aircraft a day. There was a delay between roll out at the factory and delivery, more so in winter, but it makes HR679 officially January 1943 production. On these numbers there is no way there were 299 series Ia from Handley Page.

General Reconnaissance squadrons, 58 received Halifax II from December 1942, Halifax III in March 1945. 502 squadron Halifax II from February 1943, Halifax III in February 1945. While Stachiw and Tattersall report the first II GR was JP258, from LAP, it was delivered on 11 March 1944.

Weather reconnaissance squadrons, 517 formed from 1404 flight in August 1943, Halifax V in November 1943, Halifax III in March 1945, 518 formed with Halifax V in July 1943, Halifax VI in March 1946. While Stachiw and Tattersall report the first V MET was DG344 from Rootes, it was delivered on 6 February 1943. So the RAF sends one of the first improved Halifaxes off for weather duty? The card for DG344 looks like it says I.

So far the aircraft cards report series Ia from May/July 1943. The following table is radiator production firstly showing there was a real official difference between the series I and Ia radiators but also giving clues about when the change over could have happened. The third column is Halifax II and V production for the month times 4, showing how many radiators were needed.

Radiator production. series I radiators may be in "others" column June to August 1944, All Halifax Series Ia radiators are in others column in September.

Month	I	Ia	II/V production x4
Jul-42​	1194	0	248
Aug-42​	1377	0	292
Sep-42​	1627	0	316
Oct-42​	1632	0	436
Nov-42​	1367	0	396
Dec-42​	1397​	16​	408​
Jan-43​	1046​	32​	484​
Feb-43​	945​	98​	548​
Mar-43​	1022​	100​	612​
Apr-43​	964​	96​	620​
May-43​	803​	222​	720​
Jun-43​	640​	284​	636​
Jul-43​	710​	365​	624​
Aug-43​	623​	486​	524​
Sep-43​	462​	481​	604​
Oct-43​	240​	536​	480​
Nov-43​	335​	355​	340​
Dec-43​	327​	393​	324​
Jan-44​	293​	366​	260​
Feb-44​	438​	336​	252​
Mar-44​	277​	359​	236​
Apr-44​	100​	284​	268​
May-44​	348​	258​	204​
Jun-44​	n/a	158​	144​
Jul-44​	n/a	166​	76​
Aug-44​	n/a	154​	0​

There is the need to stock the supply and maintenance systems and probably early series Ia production was warehoused for a time before being released to the factories. Mathematically if you release all the series Ia radiators built so far to the factories in May 1943 you still cannot make all production for the month series Ia, you have to wait until June. It takes until October before series Ia radiator production exceeds the number needed to equip all new Halifax production for the month.

Conclusion the change over to series Ia was in Q2 and Q3 1943 even assuming English Electric never changed.

Another point on the idea Handley page built series Ia from mid December 1942 onwards. Handley Page production to end June 1943 requires 584 series Ia radiators, 342 were built. Devoting every series Ia radiator to Handley Page built Halifaxes, it takes until July before there is enough to equip the December 1942 to July 1943 output. If Handley Page really did built 299 series Ia a lot of them waited for weeks for their radiators.

It is going to take looking at the individual aircraft cards to come up with an estimate of the series split and English Electric either never changed over or did not mark the cards.

 

[33k in the air]

As a general question from looking at the Form 78 cards, why were some aircraft first taken on charge by maintenance units while others first by squadrons?

For example, HR736 was first taken on charge by 48 MU on 27 Feb. 1943, and then by 35 Squadron on 17 March 1943, while HR747 was first taken on charge by 8 MU on 11 March 1943, and then by 51 Squadron on 28 April 1943. In contrast, HR751 is first taken on charge by 158 Squadron on 12 March 1943, while HR754 was first taken on charge by 102 Squadron on 14 March 1943. Neither started at a maintenance unit.

 

[ThomasP]

Although I do not know if this applies to the particular aircraft you are referring to, there were often different Modifications for different Sqns/Groups - sometimes depending on environment and/or the mission types being flown, and some would be requested by the Unit Commanders due to operational preferences or testing.

Due to the push for production, it was usually found to be less complicated to complete the airframes as 'standard' and then send them to the M.U. for Modification.

One example I ran across a long time (20 years?) ago in a memo/dispatch involved radiators for the Hurricane. My understanding is that all of the SeaHurricane Mk IIC were new build on the production lines. The memo requested that 18x SeaHurricane Mk IIC airframes be Modified at a M.U. (I think it was M.U.) and have 'Tropical' radiators fitted. These particular airframes were being sent to the MTO.

I later (a couple of years ago) ran across reference to the 'Temperate' and 'Tropical' radiators in a Modification list and the Mod for the 'Tropical' radiator included the term "S.O.O." - which I learned just recently (on this forum) means 'Special Order Only'.

So, maybe this is what was going on with the Halifax airframes in question. I do not necessarily mean the radiator types being changed, but maybe special and/or additional equipment being fitted depending on the mission type and purpose of the airframe (ie H2S, ASV, Sqn Leader, Pathfinder, Communications, etc).

 

[33k in the air]

Although I do not know if this applies to the particular aircraft you are referring to, there were often different Modifications for different Sqns/Groups - sometimes depending on environment and/or the mission types being flown, and some would be requested by the Unit Commanders due to operational preferences or testing.

That would be my first thought, but it sometimes seems difficult to find a pattern for that which matches up to the serial number runs. But admittedly this is from a quick spot check.

 

[33k in the air]

Just an FYI to pass along for anyone looking at the Form 78 cards. I saw entries which appeared to read "C-Owen" and I wondered what that referred to, since it was not included in the list of abbreviations the Bomber Command History website provides.

From going through the books I have on hand, it would appear "C-Owen" refers to Cunliffe-Owen Aircraft, which was where Mk II and V planes were modified into GR versions for Coastal Command. So this would provide a way to approximate the number of Halifax II and V aircraft converted for maritime work.

 

[Geoffrey Sinclair]

As I understand it Cunliffe-Owen did the MET conversions, so look where the aircraft went afterwards, 58/502 or 517/518. With only a pair of GR squadrons and a pair of weather reconnaissance squadrons, each having lower loss rates than the bomber units, making the changes they required on the production line was not economical.

If the aircraft were coming off the lines fully ready to go into service, which was not always the case, and a unit wanted a new aircraft, which was often the case, it makes sense to send it direct, not via a Maintenance Unit.

 

[33k in the air]

As I understand it Cunliffe-Owen did the MET conversions, so look where the aircraft went afterwards, 58/502 or 517/518.

I'm probably going to that. At some point I'm going to go through each serial number and its associated Form 78 card (if available) and note the first date that aircraft was assigned to a squadron and which squadron that was. It'll be interesting to see exactly when aircraft arrived at squadrons (for those that went to one).

 

[wokelly]

I'm unclear if the Series I (Special) was only from conversions of Series I aircraft, or if some came out of the factory that way. Photos and illustrations of Series I (Special) aircraft show some with no dorsal turret, some with the two-gun dorsal turret, and some with the four-gun dorsal turret. So alterations and variations for this subvariant seem not uncommon.

I'm not sure if you're still unresolved about production of Series 1A's vs modifications, but a Bomber Command operational Research report I have from November 1943 suggests that the Series 1A were made up of both aircraft produced in factory, and also older Halifax models modified to the Series 1A standard. I would guess the ones without dorsal turrets or the 2 gun ones were the older Halifax models brought up to Series 1A standard (as far as possible), especially those lacking a dorsal turret as that was a very common modification in early 1943 when the Halifaxes had the "Z-fairing" instead of the glazed nose.

This image is from "ORS BC #90 - Monthly Review of Losses and Interceptions of Bomber Command Aircraft in Night Operations – November 1943" which can be seen on my website.

 

[33k in the air]

I'm not sure if you're still unresolved about production of Series 1A's vs modifications, but a Bomber Command operational Research report I have from November 1943 suggests that the Series 1A were made up of both aircraft produced in factory, and also older Halifax models modified to the Series 1A standard. I would guess the ones without dorsal turrets or the 2 gun ones were the older Halifax models brought up to Series 1A standard (as far as possible), especially those lacking a dorsal turret as that was a very common modification in early 1943 when the Halifaxes had the "Z-fairing" instead of the glazed nose.

View attachment 718766

This image is from "ORS BC #90 - Monthly Review of Losses and Interceptions of Bomber Command Aircraft in Night Operations – November 1943" which can be seen on my website.

Thanks for the info!

I actually started going through all the Form 78 cards for the Halifax, noting which were designated as Series I or Series Ia. I thought it was worth compiling the data from those, even that too would be imperfect. (I still have yet to finish this task.) Unlike with U.S. production, where numbers of individual production blocks can often be determined, it seems U.K. production tracking was less detailed. And of course the subsequent modifications muddy things even more.

Ah well, one can only work with what one has.


By the way, I'm a subscriber to your YouTube channel (under a different name) and I've bookmarked your website. There's great stuff on both!

 

[wokelly]

Ah well, one can only work with what one has.

Ah yes, I know that feeling.