halifax IV HR756 engine nacelle type ?

[brewerjerry]

Hi

    curiosity is getting me, just saw online a photo of Halifax IV HR75

        and i am wondering if the modification to Mk IV was sort of to just to put 'lancaster style' engine pods to the aircraft and use four blade props 

    cheers

        jerry 

Edited March 4, 2023 by brewerjerry

[Troy Smith]

1 hour ago, brewerjerry said:

just saw online a photo of Halifax IV HR75

the photo would help, I just searched and could not find it.

 

I don't recall reading about this, though likely i just forgot as I have a few Halifax books.

"Handley Page Halifax IV: Projected development of Mk II with 1,280 hp Merlin 60s (HP.60A), with long-tailed inner nacelles and totally-enclosed wheel bays, enlarged fins and rudders, enlarged bomb-doors for 8,000 lb (3,632 kg) block-busters and extended span. One Mk II tested with Merlin XXs in Merlin 60 powerplants as Mk II Srs 2 in March 1943, later used as test-bed for Merlin 61s and 65s, with long-tailed inner nacelles but original fins and rudders and short span wing."

 

one perhaps for @Graham Boak ?

[brewerjerry]

Hi

    just asked someone if they can post the photo for me 

    cheers

        jerry 

Edited March 4, 2023 by brewerjerry
typo

[Troy Smith]

23 minutes ago, brewerjerry said:

just asked some if they can post the photo for me

if it's online and not on one of 'not to be hotlinked'  list, right click image, copy image address and just pate that in where you type,  if the image shows it works.  Or, just put the picture URL in the link box.   It just show as a link then.

HTH

[Geoffrey Sinclair]

According to AVIA 46/112 the Halifax Biography.

“In the summer of 1941 Rolls Royce produced the Merlin 60 high altitude engine and Handley Page’s suggested that a new version of the Halifax should be developed with the following modifications,

1) Equipped with the Merlin 60 high altitude engine.

2) Span of 104 feet instead of 99 feet.

3) Redesigned the bomb bay which would enable 4000 and 8000 pound bombs to be carried without special carriers so that the bomb bay doors would close for the 4000 pound bombs and very nearly close when 8000 pound bombs were carried.

 

This aircraft was known as the Halifax IV and although the Ministry of Aircraft Production agreed that a prototype should be built and a contract was issued in September 1942, the project did not get very far and was later abandoned, as a result of the decision taken to change over entirely to Hercules engine for all Halifax aircraft.  This decision was taken in February 1943 mainly on account of the uncertainty of the Merlin production.”

 

Merlin 60 series were at a premium in 1942/43, remembering Spitfire V production did not end at Castle Bromwich until August 1943 and Westland in October.

 

HR756 a mark II series I, fitted with Merlin 22, taken on charge 8 April 1943, about 2 to 3 weeks after the serials just before it, Controller of Research and Development at the Royal Aircraft Establishment, Rolls Royce 24 June 1943, 44 MU 6 May 1944, Bomb Ballistics Unit 21 June 1944, Category AC flying accident 17 April 1945, Repaired on Site, 60 MU 26 April 1945, BBU 11 June 1945, Controller of Research and Development at the BBU 30 August, Struck Off Charge 24 January 1946.

[Graham Boak]

According to Merrick, and with a photograph, HR756 was the only Mk.II series II, and included features intended for the Mk.IV.  This retained the Merlin 22 engines of the series IA but with dropped nacelles, extended tails to the nacelles, enclosed wheel wells, six-a-side exhausts, deep radiators baths (as RR power eggs on Lancaster/Beaufighter) and Beaufighter-type spinners.  This still had the earlier fins/rudders, and no deepened bombbay.  HR756 was later fitted with Merlin 85s, then 65s, but by then the Hercules-powered variant was in production.  And, as said above, where were the Merlin 60s to come from?

 

Although a fully developed version of this airframe could well have been referred to as a B.Mk.IV, Merrick includes a copy of a company drawing for the HP.60A or Mk.IV which included turbocharged Hercules, an enlarged wing, and a deepened bombbay with deepened forward fuselage and twin mainwheels.  Presumably a second projected use of the Mk.IV designation.

 

EDIT.  Thinking on, this drawing (simply labelled as Halifax) would appear to be closer to the proposed HP63(?) Hastings bomber and may be the first attempt at this.  The later transport reused the name but little else, having an extended (basically by means of inserts) Halifax wing.

[Graham Boak]

Looking further, into Barnes' Handley Page Aircraft since 1907, the drawing discussed is of the HP65 with new laminar flow wing.  When fitted with a more conventional wing this became the HP66 Hastings B1 with Hercules 100s, and the HP67 Hastings B2 with turbocharged Hercules.  As a backup, the Hastings BI was to be capable of being fitted with the RAE's standardised cylindrical nacelle containing Merlin 85s as seen on the Windsor and the Lincoln (and the Shackleton?)   These nacelles were trial-installed in Halifaxes BII DG296 and BIII LV795.  It would be interesting to see photos of these two and knowledge of their testing, if flown.   Presumably it would also have been fitted, had it appeared, with the RAE's 'ideal' nose position as on the Lincoln, but this is not discussed.  The HP66 was cancelled when priority was given to the HP71 Halifax A9.  Initially alongside these were the HP64 civil transport/military freighter which was superseded by the adoption of the HP66 wing and name to become the HP67 Hastings and HP68 Hermes. 

 

The HP63 was the Halifax V.

Edited March 4, 2023 by Graham Boak
Getting confusing items tidied up.

[brewerjerry]

Hi All

          Many thanks for all the info on the MkIV 

 

so the engine nacelle shape is similar visually to the lancaster nacelles,  my eyes were not deceiving me

    cheers

       jerry 

[Graham Boak]

Glad you liked it, but to be pedantic with the standard Merlin 22 it is only the Mk.II series 2,  Whatever else they came up with for the Mk.IV (at various times) it would have had different nacelles.  At one time I did manage to get a set of the postwar cowlings but it just ended up as yet another unstarted project.  

[brewerjerry]

2 minutes ago, Graham Boak said:

Glad you liked it, but to be pedantic with the standard Merlin 22 it is only the Mk.II series 2,  Whatever else they came up with for the Mk.IV (at various times) it would have had different nacelles.  At one time I did manage to get a set of the postwar cowlings but it just ended up as yet another unstarted project.  

 Hi graham

                     the photo shows four blade props so must be a little bit later in the engine swaps ? 

 

     anyone interested in the  pm your e mail and i will send the photo 

 

       cheers

          jerry 

[Graham Boak]

A good point, but 4-bladers were not uncommon in M22 Halifaxes, or even on earlier wearier examples in the HCUs.  The longer engine of the 2-stage compressor on the M60 series would have required longer cowlings, and greater radiator size.  Merrick does describe it as having greater radiator size, but this could just be in comparison with the normal M22 fit.  However, Barnes does say that this was built for the M60 but only M22s were initially available - so perhaps this is indeed showing the final appearance.  He goes on to say that M61 and 65 were fitted during its stay at RR, but doesn't mention the M85.  Other  differences between this airframe and any Mk.IV is that it retained the original wingspan (and in the photo, the fins.  I suspect that this will have changed at some convenient time.

 

One interesting comment by Merrick is that the intakes for the cabin heating system were removed from the top of the inner engine cowlings and replaced by small intakes underneath each wing, near the root.  There's no such thing as a simple aircraft.

[dogsbody]

@brewerjerry's photo:

 

 

 

 

 

Chris, for Jerry

[Geoffrey Sinclair]

16 hours ago, Graham Boak said:

the RAE's standardised cylindrical nacelle containing Merlin 85s as seen on the Windsor and the Lincoln (and the Shackleton?)   These nacelles were trial-installed in Halifaxes BII DG296 and BIII LV795. 

Sure about the serials, and any idea when the trial nacelles were installed?

 

DG296 mark V built by Rootes, Merlin XX, 48 MU 12 December 1942, 1664 CU 2 July 1943, 431 Squadron 1 September 1943, 1664 CU 2 September 1943, 1666 CU 20 September 1944 48 MU Hooton Park 4 January 1945, Struck Off Charge 1 November.

LV795 mark III built by Hadley Page, direct to 78 squadron 14 January 1944, Category AC 8 May, Handley Page repair in works 19 May, Struck off charge 9 June.  Listed as category E 19 May in Serial Registers.

 

According to AVIA 46/112 the Halifax Biography.  The two related Merlin powered proposed improvements to the Halifax.

“Halifax II series II.

This mark was the aircraft in which the engine nacelles were lowered relative to the wing, a modification which was expected to improve the performance.  The engine was to be the high altitude Merlin 61.  One prototype was built and when flight tested in April/May 1943 showed a worthwhile gain in performance.  This development however had no practical application because in February 1943 it was decided to change over entirely to Hercules engine for all Halifax aircraft on account of the uncertainty of Merlin production.

….

In the summer of 1941 Rolls Royce produced the Merlin 60 high altitude engine and Handley Page’s suggested that a new version of the Halifax should be developed with the following modifications,

1) Equipped with the Merlin 60 high altitude engine.

2) Span of 104 feet instead of 99 feet.

3) Redesigned the bomb bay which would enable 4000 and 8000 pound bombs to be carried without special carriers so that the bomb bay doors would close for the 4000 pound bombs and very nearly close when 8000 pound bombs were carried.

 

This aircraft was known as the Halifax IV and although the Ministry of Aircraft Production agreed that a prototype should be built and a contract was issued in September 1942, the project did not get very far and was later abandoned, as a result of the decision taken to change over entirely to Hercules engine for all Halifax aircraft.  This decision was taken in February 1943 mainly on account of the uncertainty of the Merlin production.”

 

The above resulted in, HR756 a mark II series I, fitted with Merlin 22, taken on charge 8 April 1943, about 2 to 3 weeks after the serials just before it, Controller of Research and Development at the Royal Aircraft Establishment, Rolls Royce 24 June 1943, 44 MU 6 May 1944, Bomb Ballistics Unit 21 June 1944, Category AC flying accident 17 April 1945, Repaired on Site, 60 MU 26 April 1945, BBU 11 June 1945, Controller of Research and Development at the BBU 30 August, Struck Off Charge 24 January 1946.

 

The rest is about the mark II and V series Ia, which appeared in a similar time frame to the proposed series II and mark IV, and where different references have different ideas on the definition and how many were built.  The prototype Ia HR679, first flew in December 1942.  Controller of Research and Development at the Aircraft and Armament Experimental Establishment 22 January 1943, Controller of Research and Development at R? Maledon? 12 August 1943, 25 Maintenance Unit 23 September then stayed in storage at various MU until converted to scrap 9 October 1946.

 

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 Merlin 22 engines began to be fitted on some lines.  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.

 

Looking at the Ministry of Aircraft Production Monthly Statistical Bulletins the radiator production table actually separates Halifax series I and Ia radiator production, see below.  Also Merlin 22 production, 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, engines also fitted to Lancasters.

 

A quick look at the individual aircraft cards shows,

Handley Page mark 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

London Aircraft Production mark 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 mark II still fitted with Merlin XX to end production in October 1943, none of the cards checked were marked Ia.

Fairey mark 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, Engines Merlin, usually no mark number.  First series Ia LK890 in July 1943, again not all cards marked. 

From this the 5 production lines the switch to series Ia was 1 in May 1943, 3 in July, 1 unknown when assuming the early series Ia cards are properly annotated. Rather later than the AIR 46/112 states.

 

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.  So far the aircraft cards report series Ia from May/July 1943. The following table is series I and Ia radiator production. The third column is Halifax II and V production for the month times 4, showing how many radiators were needed.  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 radiator 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.

 

General Reconnaissance versions, 58 squadron received Halifax II from December 1942, Halifax III in March 1945. 502 squadron Halifax II from February 1943, Halifax III in February 1945.

 

Weather reconnaissance versions, 517 squadron 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.

 

The Ministry of Aircraft Production Monthly Statistical Bulletins do not record any 4 blade propeller production for Halifax until January 1944, but then say 242 made for the month, out of the planned 250.

[Graham Boak]

According to Barnes, when discussing the HP65/66/69.  The new 115 ft laminar flow wing of the HP65 was abandoned in favour of an extended version of the standard wing proposed by N E Rowe (DTD - Director of Technical Development) i.e. the eventual Hastings transport wing.  This produced the Hastings bomber projects HP66/69 as previously described, with three prototypes ordered.  "As an insurance, Merlin 65s, in cylindrical RAE "idealised" powerplants interchangeable with Hercules, were also envisaged for the HP66, following trial installations (with four-blade airscrews) in Halifax II DG296 and Halifax III LV795..."  Whether this was ever carried out is doubtful, but it seems that these two aircraft were allocated at some stage.  That a B.III was included suggests the intended trials were later than the cancellation of all B.IV studies.  Merrick's reference to the Merlin 85 is that they were fitted to HR756 in June - in context 1943 - following initial flights with M22s in April and May and that M65 were fitted later.  Which seems the wrong way around.  Possibly the M85 could have been fitted (for trials?) into an extended standard power egg but they are seen on the Lancaster and later types with the RAE cylindrical cowling.

 

The Mk.II prototype L9515 was the first aircraft fitted with the extended nacelles, designed to counter reported oscillations traced to vortex shedding from the inner nacelles. They were later fitted to HR679, HR756 and HR876.  This according to Barnes: Merrick links this to deeper studies of turbulent flow over the inner nacelle leading to suggestions for a lowered nacelle and other modifications.  HR679 became the Mk.II series 1A prototype with the standard (high) engine position, and flew in December 1942.  The full combination of features was not accepted because of the necessary disruption to production, the extended tails by themselves showing only marginal benefits.  I have found no further reference to HR876.  

 

The first trials of 4-bladers on the Halifax were carried out on an unspecified B.II date unspecified but mid 1943, followed shortly afterwards by B.V DK145.  However they are also seen on HR756 which had flown in April 1943.  (Could this be the unspecified Mk.II?)  Merrick states that they were mainly fitted to Mk.Vs and Coastal Command: photos of SOE Mk.IIs in Italy 1945 show these props (and the final form of the exhausts) but these are well downstream.  (Also mainly London Transport built aircraft in the JP range).   Mid-1943 trials would seem to be consistent with mass production for 1944, but these early examples have to come from somewhere.

 

The photo above is not the one in Barnes nor the one in Merrick, but all three are taken from much the same angle and the reproduction above is the best.  Barnes credits his to the IWM and that it shows the aircraft with M65s at Hucknall.  (So here it is a Mk.IV?)  The photo does show two vertical parallel lines of rivets ahead of the wing leading edge which could correspond to a longer engine, and assist the modeller.  Whether the radiators are deeper than those of the standard RR Merlin power egg I can't say from the photo but extra cooling would be required.  I suspect RR records would be the best place to look for these.  A modelling note is the bulge on the wheel door, showing that the nacelle wasn't deepened so much as to fully enclose the wheel inside its bottom line.

 

What is clear to me from all this is that the Mk.IV was applied to different aircraft at different times.  Initially it was a Mk.II variant with M60-series engines and various improvements including a 104 ft wing - this is the round-tipped Halifax wing as seen on all late marks.  It was later applied, possibly only within HP, to the HP65 and its laminar 115 ft wing with simple taper.  Whether the fuselage of the HP65 was the same as that intended at some stage for the Mk.IV perhaps suggests an extra intermediate stage in the design process.

 

To pick up on a couple of points: the low engine position was found to produce lower drag in studies from the RAE produced after the design of the Halifax but before the design of the Lancaster.  The Morris block radiators were superior to the Gallay type but were also seen on the Manchester - sadly for the type the Halifax was (unavoidably) committed to production too early for these two significant improvements.