An Allison V-1710 with a two-speed supercharger in 1942 (1 Viewer)

[drgondog]

The changes to the inner structure of the wing when moving from NA-83/91 wing to A-36 were not major issue, structurally speaking because the dominant loading remained Angle of Attack load for high G turn and dive pullout.

The dive brake introduced new load considerations but the stresses to internal wing structure like the spar and external structure such as skin thickness to increase torque box rigidity were only to increase 0.040 to 0.64 along the leading edge.

The dominant load factors were drag and sideways loads which introduced moments to the new bomb rack plus introduced aerodyamic safe load envelope to approximately 400 mph on the dive brakes. The latter mandated a warning in the operating manual of the A-36 to ALWAYS open dive brakes BEFORE exceeding 350mph and before entering a dive. There were two fatal A-36 accidents when two French pilots entered their dives before the brakes were extended. Both had catastrophic failures at WS 75 - which led Training Command to order the brakes wired shut and limit bomb load to 500 ponds). The A-36 was analyzed and accepted for 1000-pound (each) bomb loads.

The centroid of the rack was at ~ 33% chord, the location of the main spar. IIRC the A-36 only had the B-7 bomb rack which was rated at 1,100 pounds. That said the P-51A/B pylons were stressed for 600 pounds and that the D did not introduce any internal structure for the D when the new pylon and B-10 equivalent rack was installed for 165-gal external fuel tanks.

All leading edge skins for A/B/D continued the A-36 leading edge skin dimension of 0.064.

The comments above regarding the design opportunity to introduce both controls and conduit/wire bundles for controlling both the bomb and the drop tank are correct.

The primary difference in design philosophy favoring P-51 and P-38 over the P-47 was that both were focused on wing tankage (and structure) from the beginning design, and both were designed for 150/330-gal wing tanks in 1942. When Republic was being hounded by Materiel Cmd to add wing pylons to carry droppable 150+gal tanks, thy had to modify many P-47C/D in the field - which was a depot level modification to open up the wing forward of the spar and add both fuel lines and controls. I have never seen the structural analysis for the P-47 as all were destroyed by Fairchild when they acquired Republic.

 

[Steamed_Banana]

The changes to the inner structure of the wing when moving from NA-83/91 wing to A-36 were not major issue, structurally speaking because the dominant loading remained Angle of Attack load for high G turn and dive pullout.

The dive brake introduced new load considerations but the stresses to internal wing structure like the spar and external structure such as skin thickness to increase torque box rigidity were only to increase 0.040 to 0.64 along the leading edge.

The dominant load factors were drag and sideways loads which introduced moments to the new bomb rack plus introduced aerodyamic safe load envelope to approximately 400 mph on the dive brakes. The latter mandated a warning in the operating manual of the A-36 to ALWAYS open dive brakes BEFORE exceeding 350mph and before entering a dive. There were two fatal A-36 accidents when two French pilots entered their dives before the brakes were extended. Both had catastrophic failures at WS 75 - which led Training Command to order the brakes wired shut and limit bomb load to 500 ponds). The A-36 was analyzed and accepted for 1000-pound (each) bomb loads.

The centroid of the rack was at ~ 33% chord, the location of the main spar. IIRC the A-36 only had the B-7 bomb rack which was rated at 1,100 pounds. That said the P-51A/B pylons were stressed for 600 pounds and that the D did not introduce any internal structure for the D when the new pylon and B-10 equivalent rack was installed for 165-gal external fuel tanks.

All leading edge skins for A/B/D continued the A-36 leading edge skin dimension of 0.064.

The comments above regarding the design opportunity to introduce both controls and conduit/wire bundles for controlling both the bomb and the drop tank are correct.

The primary difference in design philosophy favoring P-51 and P-38 over the P-47 was that both were focused on wing tankage (and structure) from the beginning design, and both were designed for 150/330-gal wing tanks in 1942. When Republic was being hounded by Materiel Cmd to add wing pylons to carry droppable 150+gal tanks, thy had to modify many P-47C/D in the field - which was a depot level modification to open up the wing forward of the spar and add both fuel lines and controls. I have never seen the structural analysis for the P-47 as all were destroyed by Fairchild when they acquired Republic.

Wow 400 mph dive speed? I think that is unusually fast dive speed for a dive bomber, it maybe explains some things!

Just quick google results (don't crucify me if these aren't accurate please)-

Douglas SBD max dive speed with dive brakes 276 mph
Vought Sb2U Vindicator - 250 mph (another source says 373 mph so )
Curtiss SB2C - 250-300 mph
Vultee A31 Vengeance - 300 mph
Aichi D3A - 276 mph
Yokosuka D4Y - 342 mph
Ju 87 - 350-370 mph
Ju 88 - 357 mph
Sukhoi Su-2 336 mph
Petlyakov Pe-2 397 mph (another source says 491 mph but that sounds ridiculous)

Based on that (if correct) it seems like A-36 was possibly the fastest diving dive-bomber to see combat during WW2

Stuka and Pe-2 also surprisingly fast-diving.

Ju-88 was fast but was taken out of the dive-bombing role (or at least, high-angle dive bombing with dive brakes) in 1943 due to stress on the wings. D4Y quite fast too but I know they had a bunch of issues diving in high speed for the first year or two so big asterix there as well.

 

[Steamed_Banana]

The Merlin VIII was pretty much a Merlin III (some parts were Merlin XII) with a 6.313 supercharger gear. Very close to the gear ratio used in the Merlin X low gear. Yes, performance at height sucked. One the other hand this shows the slow pace of British construction of the time. The first production order was placed in mid 1938 (?) and first production plane was delivered in Jan 1940. Perhaps the Air Ministry could have requested Merlin X engines? But such a request should have been done either at the initial order or shortly after. Switching engines only a few weeks or two months before expected delivery was going to cause a lot a waves in production of the aircraft you are swiping the better engines from.
Merlin 30 was the original 'cropped' Merlin. It used a 9.75in impeller and the original 8.588 gear ratio of the Merlin III. Used a lot more parts in common with the Merlin XII and the stronger parts allowed for higher boost.
Fulmar II started leaving the factory in Jan 1941. Unfortunately, the Fulmar was rather low on the list for better engines. A two speed Fulmar would have been better, but in Jan-June of 1941 there were a number of other aircraft that needed the two speed engines more, although swiping the engines from the Defiant IIs would have been a plus. Unfortunately the Defiant II production started in the summer of 1941, not 1940 so they aren't much help.
A high altitude (over 10,000ft?) Fulmar would have been interesting. Actual need might not have been that great. Fulmars really needed to stop torpedo bombers and low altitude bombers. With hindsight we know that high altitude (over 10,000ft) level bombers didn't hit much anyway

This is indeed true but dive bombers, which were arguably the biggest threat for Royal Navy convoys and military vessels in WW2, typically initiated dives from above 10,000 ft, and both their close escorts and high cover if any were sometimes a problem for Fulmars in the various convoy fights. If Fulmar had been able to perform better at altitude it might have been used a bit more often within the range of enemy land based fighters.

chasing off snoopers was another important job and here they were aided by the Italians using their own low altitude planes (float and flying boat?) to bulk out numbers.
One wonders if a Merlin 45 with a small change in gear ratio and 9.75in prop instead of the 9.5in 45M impeller could have added 3000+ft plus the Fulmars operational height without going to the two speed supercharger? The Merin 32 showed up late.
The successors to the Fulmar and Swordfish showed up very late.

The initial successor to the Fulmar was basically the Wildcat, and the successor to the Swordfish was basically the TBF, which couldn't dive bomb but proved quite effective in the ASW role which quickly became one of the most important missions for the FAA.

Maybe the British would have been much better served by a Fulmar III with a two speed Merlin rather than waiting for the Firefly until 1944?

That's the idea precisely. It would only mean few hundred fighters at most, and probably no more than a couple of dozen that actually faced enemy fighters, but those combats were during rather important moments in the war.

 

[drgondog]

Wow 400 mph dive speed? I think that is unusually fast dive speed for a dive bomber, it maybe explains some things!

Just quick google results (don't crucify me if these aren't accurate please)-

Douglas SBD max dive speed with dive brakes 276 mph
Vought Sb2U Vindicator - 250 mph (another source says 373 mph so )
Curtiss SB2C - 250-300 mph
Vultee A31 Vengeance - 300 mph
Aichi D3A - 276 mph
Yokosuka D4Y - 342 mph
Ju 87 - 350-370 mph
Ju 88 - 357 mph
Sukhoi Su-2 336 mph
Petlyakov Pe-2 397 mph (another source says 491 mph but that sounds ridiculous)

Based on that (if correct) it seems like A-36 was possibly the fastest diving dive-bomber to see combat during WW2

Stuka and Pe-2 also surprisingly fast-diving. D4Y quite fast too but I know they had a bunch of issues diving in high speed for the first year or two so big asterix there.

The DESIGN limit dive speed, not the operational dive speed with dive brakes extended which was 350-375mph depending on the angle.

 

[Steamed_Banana]

The DESIGN limit dive speed, not the operational dive speed with dive brakes extended which was 350-375mph depending on the angle.

Still quite fast

 

[Shortround6]

Two problems with fast diving.
1, you have less time to aim.
2, you have to pull out at a higher altitude to keep from hitting the ground.

 

[Shortround6]

This is indeed true but dive bombers, which were arguably the biggest threat for Royal Navy convoys and military vessels in WW2, typically initiated dives from above 10,000 ft,

It was a war of attrition. A least shooting down the dive bombers at the end of their dives meant they could not come back the next day and bomb you again

The initial successor to the Fulmar was basically the Wildcat, and the successor to the Swordfish was basically the TBF

Both American which puts them out British planning for production. British use of the TBF really shows up how messed up British planning/production was in regard to the FAA.
Barracuda was built in response to a 1937 specification. TBF was in response to a 1938/39 Specification. Barracuda first flew in Jan 1941 after a delay due to change of engine, TBF first flew in Aug 1941. TBF went into action with the US in June of 1942 in small numbers, rapidly expanded. Barracuda, after getting a newer model Merlin (3rd engine?) went into service in Jan 1943 and into combat in July 1943. Around 8 to 12 months late?

That's the idea precisely. It would only mean few hundred fighters at most, and probably no more than a couple of dozen that actually faced enemy fighters,

It would have been better, the problem is was it was going to be enough better.
Fulmar had 342 sq ft of wing, more than a P-38 or F6F (only a little), it was lighter (didn't have the R-2800)
But even a Merlin XX (or V-1650-1) was going to allow it fight either 109s or Zeros at 12-20,000ft.
Fulmar had about 50% more wing than a P-40F and weighed almost 1000lbs more clean with the eight .303 guns.

 

[Steamed_Banana]

Two problems with fast diving.
1, you have less time to aim.
2, you have to pull out at a higher altitude to keep from hitting the ground.

Correct.

Two advantages with fast diving:

1. Harder for flak to hit you
2. Harder for fighters to catch you
3. (possibly) greater accuracy (debatable)

I think the first two are really key, though the last could also be a thing. Both the A-36 and the Ju 88 were known to be quite accurate bombers.

 

[Shortround6]

wrong thread

 

[Steamed_Banana]

It was a war of attrition. A least shooting down the dive bombers at the end of their dives meant they could not come back the next day and bomb you again

If they can catch them. Fulmar wasn't that fast even on the deck (where for one thing, the air is thicker and therefore more drag, slower acceleration etc.). Meanwhile a dive-bomber pulling out of a dive has a pretty good head of steam on. CAP for a convoy or a carrier can't chase a fleeing dive bomber forever especially if more enemy aircraft may be on the way. In the event I don't think they shot down that many Ju 87s or Ju 88s..

I would also note that in carrier war or convoy fights, it's not necessarily just an attrition war. A carrier being hit and either lost or taken out of action / sent back to drydock for months can be a strategic problem, as can the failure of a convoy. Pedastal was a pretty important supply run for example, which had it failed, could have led to the loss of Malta. If the SS Ohio had been sunk at sea, that could have been a bit sticky for the Allies, even if .

Both American which puts them out British planning for production. British use of the TBF really shows up how messed up British planning/production was in regard to the FAA.
Barracuda was built in response to a 1937 specification. TBF was in response to a 1938/39 Specification. Barracuda first flew in Jan 1941 after a delay due to change of engine, TBF first flew in Aug 1941. TBF went into action with the US in June of 1942 in small numbers, rapidly expanded. Barracuda, after getting a newer model Merlin (3rd engine?) went into service in Jan 1943 and into combat in July 1943. Around 8 to 12 months late?

And not super useful in Theater when they did arrive, especially in the Pacific.

TBF was a weird kind of miracle. It was at least twice as large as any single engined bomber had any right to be, (they are about the size of a middling bus), but it was fairly effective, surprisingly agile for it's size, and best of all could operate from small escort carriers.

It would have been better, the problem is was it was going to be enough better.
Fulmar had 342 sq ft of wing, more than a P-38 or F6F (only a little), it was lighter (didn't have the R-2800)
But even a Merlin XX (or V-1650-1) was going to allow it fight either 109s or Zeros at 12-20,000ft.

Whether it's allowed or not, Fulmar's did have to fight both Bf 109s and A6Ms, as well as other fighters like MC 202s, Bf 110s, Fiat G.50 and Macchi MC. 200, Re 2000 (or 2001, I forget which). A top speed at altitude of 220 mph was really bad. Roughly 260 or 270 mph is still bad, but it's definitely better. Fulmar had some advantage of a tight turning circle which helped somewhat against the German and Italian fighters, though I don't imagine roll rate was exactly electrifying.

Fulmar had about 50% more wing than a P-40F and weighed almost 1000lbs more clean with the eight .303 guns.

I'm hip, it's a very large aircraft, I have model kits of both behind me on the shelf. But it did have some capability as a fighter and that Merlin XX would have helped both in the interception of enemy aircraft, especially dive bombers and recon planes flying at altitude, as well as give it a little more of a chance against land based fighters.

 

[Steamed_Banana]

wrong thread

Are we referring to your post or one of mine?

 

[SaparotRob]

Two problems with fast diving.
1, you have less time to aim.
2, you have to pull out at a higher altitude to keep from hitting the ground.

But you get a totally awesome Go-Pro video.

 

[Shortround6]

Are we referring to your post or one of mine?

Mine, I put the entry for a different thread in this one.

 

[Geoffrey Sinclair]

You asked me to point out what your areas of expertise are. You nailed it right here. That is your most accurate statement that I have ever read on this forum.

I was offered a long range detected summary of my areas of expertise and took the offer, which becomes twisted into the above.

Beyond that, I don't know how even you read that whole post, the chances of me reading it are zero.

Ah know it is unreadable by not reading it, explains the attitude to evidence. No reading was the expected result. Written to leave on a good note for a chill out weekend.

There is no traction and the wheels just spin forever, or in your case, forever to the power of infinity.

Forever to the power of infinity is something beyond divine in power terms.

On treating units differently when in different commands, 31st with 12th Air Force, 52nd with Coastal Air Force

1 August 1943, 31st FG 73 Spitfire, 52nd FG 65 Spitfire V, 10 IX
26 September 1943, 31st FG 42 V, 9 VIII, 18 IX, 52nd FG 62 V, 1 VIII, 12 IX
6 February 1944, 31st FG 8 V, 29 VIII, 38 IX, 52nd FG 56 V, 2 VIII, 10 IX
27 February 1944, 31st FG 3 V, 26 VIII, 41 IX, 52nd FG 55 V, 2 VIII, 14 IX
1 April 1944, 31st FG going to 15th AF and Mustang, 52nd FG 53 V, 1 VIII, 20 IX

The abundance of data when dealing with an air force is a big problem for authors trying to write a diary that is complete but also readable. The following is from a partial report of 12th Air Force activities in December 1943, it does NOT include any bombing sorties at least, even so 480 entries for the month. Effective sorties reported,

10 AA Calibration
23 Air Sea Rescue
16 Artillery Adjustment
54 Delousing Mission
53 Engagement
311 Escort Bomber
170 Escort Fighter Bomber
10 Escort Special
1200 Land Patrol
176 Land Reconnaissance
34 Leaflet Dropping
31 Naval Patrol
84 Photo Reconnaissance
20 Ration Dropping
26 Scramble
300 Strafing
111 Sweep
53 Weather Reconnaissance
2682 Total

The breakdown for 14th to 16th December, three busy days, plenty of typos in the names and notes by the way.

Day

Mission

Unit

Type

Sortie

Ammo.

Claims

Losses

Day

Mission

Unit

Type

Eff.

Non Eff

Non

20mm

0.5"

0.303"

Type

Dest

Prob

Damg

Dest

Miss

Dam

Note

14​

Engagement

324​

P-40

8​

1010​

Enc 7 e/a, no claims made

14​

Escort Bomber

31​

Spitfire

12​

A-20 to Pontecorvo

14​

Escort Fighter Bomber

31​

Spitfire

12​

240​

1300​

Ju88?

1​

A-36 to Civitavecchia

14​

Land Patrol

31​

Spitfire

12​

Mouth of Garigliano to G-8224

14​

Land Patrol

31​

Spitfire

11​

368​

1110​

Bf109

1​

Mouth of Garigliano to H-0050, encountered 8 E/A

14​

Land Patrol

31​

Spitfire

8​

Atina to Cassino

14​

Land Patrol

31​

Spitfire

12​

H-2030 to M-7528

14​

Land Patrol

31​

Spitfire

10​

Mouth of Garigliano to H-0040, encountered 15 E/A

14​

Land Patrol

31​

Spitfire

10​

Bf109

1​

Isernia to coast, encoutered 1 E/A

14​

Land Patrol

415​

Beaufighter

2​

Gulf of Gaeta

14​

Leaflet Dropping

12​

B-25

1​

Itri

14​

Leaflet Dropping

12​

B-25

1​

1​

Ceccano

14​

Leaflet Dropping

12​

B-25

2​

S Giorgio and S Elia

14​

Photo Reconnaissance

111​

P-51

2​

Cassino, Atina, Venafro

14​

Photo Reconnaissance

111​

P-51

2​

Cassino, Valmontone, Fondi

14​

Photo Reconnaissance

111​

P-51

2​

Atina, Avezzano, Cassino

14​

Photo Reconnaissance

111​

P-51

2​

S. Biagio, Atina, Mignano

14​

Photo Reconnaissance

111​

P-51

2​

Cassino, Atina, S. Biagio

14​

Photo Reconnaissance

111​

P-51

2​

Cassino, Sora, Atina

14​

Photo Reconnaissance

111​

P-51

2​

Mignano, Ceccano, Fondi

14​

Photo Reconnaissance

111​

P-51

2​

Pontecorvo, Sera, Cassino

14​

Weather Reconnaissance

324​

P-40

2​

Gaeta and Pontecorvo

14​

Weather Reconnaissance

31​

Spitfire

2​

To Rome, back along coast

15​

Air Sea Rescue

86​

A-36

4​

Failed to locate A-20 crew

15​

Air Sea Rescue

31​

Spitfire

6​

Escort rescue launch M-2085 to F-9200

15​

Air Sea Rescue

31​

Spitfire

6​

Escort rescue launch M-6452 to L9393

15​

Escort Bomber

31​

Spitfire

14​

A-20 to Frosinore

15​

Land Patrol

31​

Spitfire

6​

368​

1110​

Bf109

1​

1​

Mouth of Garigliano to Venafro

15​

Land Patrol

31​

Spitfire

12​

Venafro to G-9010

15​

Land Patrol

31​

Spitfire

12​

Mouth of Garigliano to H-0035

15​

Land Patrol

31​

Spitfire

6​

Gaeta to Venafro, encountered 8 E/A

15​

Land Patrol

31​

Spitfire

12​

140​

1480​

Fw190

1​

2​

1​

Mouth of Garigliano to Venafro

15​

Land Patrol

31​

Spitfire

8​

Atina and Cassino

15​

Land Patrol

31​

Spitfire

6​

Mouth of Garigliano to H-0035

15​

Land Patrol

415​

Beaufighter

3​

Gulf of Gaeta

15​

Land Reconnaissance

111​

P-51

2​

Cassino, Opi, Arce

15​

Land Reconnaissance

111​

P-51

2​

S. Dinato, S. Biagio, Cassino

15​

Land Reconnaissance

111​

P-51

2​

Capua, Atina, Cassino

15​

Land Reconnaissance

111​

P-51

2​

Cassino, Isola, Avezzano

15​

Leaflet Dropping

12​

B-25

3​

Chisti

15​

Leaflet Dropping

12​

B-25

1​

No rendesvous with escort

15​

Leaflet Dropping

12​

B-25

2​

S. Elia

15​

Photo Reconnaissance

111​

P-51

2​

Cassino, Sora, Atina

15​

Photo Reconnaissance

111​

P-51

2​

Atina, S. Biagio

15​

Photo Reconnaissance

111​

P-51

2​

Venafro, Sora, Cassino

15​

Strafing

57​

P-40

12​

5000​

Strafed 3 whses, 2 storage tanks, NRO, E-9839

15​

Strafing

57​

P-40

11​

900​

2 m/t dest at V-9991

15​

Strafing

57​

P-47

6​

1534​

Strafed 1258 M/V believeed damaged in Drace area

15​

Strafing

57​

P-40

12​

10766​

1​

Strafed E/A, 4 dest, petrol dump set on fire, 3 other e/a dest, 1 prob, silenced m/g ZAPA

15​

Sweep

57​

P-40

12​

Omis-Ston Area

15​

Sweep

79​

P-40

12​

Ancoa

15​

Weather Reconnaissance

31​

Spitfire

2​

N of Gaeta

16​

Artillery Adjustment

111​

P-51

2​

S. Bagio area

16​

Engagement

57​

P-40

12​

10007​

Bf109

2​

1​

4​

1​

Enc 7 e/a along Dalmation coast

16​

Escort Bomber

31​

Spitfire

34​

A-20 to Cervaro

16​

Escort Fighter Bomber

86​

A-36

1​

1 A-36 returning, mechanical failure

16​

Escort Fighter Bomber

57​

P-47

6​

P-40 strafing in Yugoslavia

16​

Land Patrol

31​

Spitfire

12​

Front Line

16​

Land Patrol

31​

Spitfire

12​

M-9490 to G-8432

16​

Land Patrol

31​

Spitfire

8​

Cassino and Venafro

16​

Land Patrol

31​

Spitfire

12​

Mouth of Garigliano to Cervaro

16​

Land Patrol

31​

Spitfire

12​

M-7596 to H-1528

16​

Land Patrol

415​

Beaufighter

1​

1​

Gulf of Gaeta

16​

Land Reconnaissance

111​

P-51

2​

Cassino, Sora, S. Donato

16​

Land Reconnaissance

111​

P-51

2​

Cassino, Sora, Atina

16​

Photo Reconnaissance

111​

P-51

2​

Cassino, Sora, Atina

16​

Photo Reconnaissance

111​

P-51

2​

Cassino, Valmontone, Fondi

16​

Scramble

31​

Spitfire

4​

H-1535, Cassino, no E/A

16​

Strafing

57​

P-40

8​

2100​

1​

Dalmation coast, dest bus laoded with pesonnel 1 bowser, 2 m/t 250 ft boat left flooding, 100 ft boat left sinking

16​

Strafing

57​

P-47

8​

9465​

Bf109

4​

1​

Started fire at sheds at Zahrea, at Drace and Troangi - enc 8 e/a

16​

Strafing

57​

P-40

9​

3965​

Strafed possible enemy camps, points alonf Vigand to Oribis road, also bldgs and train

Totals

451​

1​

2​

1116​

44747​

5000​

10​

1​

5​

3​

1​

4​

Now compare it with the Mediterranean Air War entries and this is just part of the 12th Air Force.

Royal Navy doctrine emphasised the torpedo bomber, requiring its fighters to have low level performance, which incidentally helped get them off the deck at a time when catapults were not favoured.

Apart from a test batch of 4 in early 1939, the 184 Merlin VIII were built November 1939 to December 1940, the 150 Fulmar I were built April to December 1940, the 450 Fulmar II December 1940 to February 1943. Merlin 30 production from November 1940 to July 1942 with a reported 660 built.

Mosquitoes required what was called reverse flow cooling, Rolls Royce built a batch of 47 Merlin 21 February to May 1941, 29 more in September then production from November, finishing in July 1943. Merlin 23 from October 1942.

Merlin XX production July to December 1940, 14, 35, 28, 57, 93, plus 6 from Glasgow in November and December an 1 from Derby in December, total 339. Hurricane II production August to December 1940, 12, 34, 24, 47, 54, total 171. Assume a 1 month delay engine to aircraft factory, 242 engines for 171 airframes.

4,788 Merlin XX in 1941, for 2,532 Hurricanes (Including some mark I) and 276 Beaufighters as priority customers and 122 out of the 207 Defiant II, there were only 83 Halifax II and 18 Lancaster I built in 1941. Engines had to normally be sea freighted from Britain to the Middle East via the Cape of Good Hope. Work out the number of replacement engines an increasing Hurricane force required per month then multiply that by say 4 to 6 for packing, shipping and unpacking time.

Jun '40_____Beafighter NF/F Mk II
Jul '40_____ Defiant Mk II
Aug'40_____Hurricane Mk II
Mar'41_____Spitfire Mk VA/B
Aug'41_____Mossi PR Mk I
Mar'42_____Lancaster Mk I
Apr'42_____Halifax Mk II
Jul '42_____Spitfire Mk IX

I have some different dates.

What was effectively the Beaufighter II prototype officially built in September 1940, production from March 1941
Defiant II production from August 1941
Hurricane II production from August 1940, rushed to units
Spitfire V production from March 1941, rushed to units
Mosquito I, 10 built July to October 1941, first issue to PRU in July, first operation 17 September
Lancaster I from October 1941, first issue to 44 squadron 24 December, first minelaying operation 3 March 1942, first bombing 10 March
Halifax II production from September 1941, issues to squadrons from late October.
Spitfire IX production from June 1942, rushed to units.

A fundamental consideration for any British what if is unless the aircraft is in production or very close to it in May 1940 or has a priority tag attached expect significant delays. Naval aircraft production was not a high priority.

Fulmar production from April 1940
Swordfish re-entered production in December 1940
Sea Hurricane conversions from early 1941, all with Merlin III, 375 conversions identified but some may have been left as mark I
Canada Sea Hurricane production, 50 mark I, November 1941 to January 1942.
Seafire production from June 1942
Firefly first one in June 1942 then series production from March 1943
Barracuda first one in July 1942 then series production from October
Late 1942 conversions of Hurricane II to Sea II, 49 identified, mostly from the Canadian built incomplete airframes, meant for Operation Torch.
Sea Hurricane II, batch of 60 built November 1942 to May 1943
Albacore production ended in December 1942.

For the USN the September 1937 to June 1938 Devastator, plus a batch of 15 more June to November 1939, it had a monoplane dive bomber in the SBD-1 from June 1940, contract signed on 8 April 1939, The XSB2C contract issued 15 May 1939, the XTBF contract issued 8 April 1940 continuing the USN pre war preference for dive over torpedo bombers. TBF-1 contract issued 23 December 1940, around 8 months before the prototype flew, SB2C-1 contract issued 19 November 1940 a month before the prototype flew.

 

[ThomasP]

Hey Geoffrey Sinclair,

Thank you for the info.

I tried to get the dates for the first more-or-less full strength squadron(s) that went operational.

I must have had a brain fart re the Defiant Mk II entering squadron size service in Jul'40. Corrected my post up-thread.

Do you know which Squadron was the first operational at more-or-less full strength with the Halifax MK II? The earliest I could find was in Apr'42.

 

[Shortround6]

Merlin XX production July to December 1940, 14, 35, 28, 57, 93, plus 6 from Glasgow in November and December an 1 from Derby in December, total 339. Hurricane II production August to December 1940, 12, 34, 24, 47, 54, total 171. Assume a 1 month delay engine to aircraft factory, 242 engines for 171 airframes.

4,788 Merlin XX in 1941, for 2,532 Hurricanes (Including some mark I) and 276 Beaufighters as priority customers and 122 out of the 207 Defiant II, there were only 83 Halifax II and 18 Lancaster I built in 1941. Engines had to normally be sea freighted from Britain to the Middle East via the Cape of Good Hope. Work out the number of replacement engines an increasing Hurricane force required per month then multiply that by say 4 to 6 for packing, shipping and unpacking time.

Thank you so much as this explains a lot of "why didn't they just do XXXXXX sooner".

 

[SaparotRob]

I have to agree with @SuperFire. We should have started building P-51s and B-29s in 1941.

 

[Steamed_Banana]

The thing is, did they need to build 2500 Hurricanes in 1941? They definitely didn't need to build any Defiants (no they weren't any use as night fighters either) and the Merlin XX didn't really work out for the Beaufighter as previously noted.

 

[Howard Gibson]

The thing is, did they need to build 2500 Hurricanes in 1941? They definitely didn't need to build any Defiants (no they weren't any use as night fighters either) and the Merlin XX didn't really work out for the Beaufighter as previously noted.

I would like to know why they built Hurricanes in 1944.

 

[yulzari]

I have to agree with @SuperFire. We should have started building P-51s and B-29s in 1941.

With hindsight of course one would. But the USA was not at war then. Except for part of one month at the end. It had been soaking up Commonwealth, in particular British, money selling arms until the customer was all but bankrupt so whatever was done would be from US government income not selling off the British family silver invested in the USA. Remember that food in Britain was not just rationed in 1939 to save shipping. It was to save foreign exchange to pay for arms imports. Hence food was still being rationed into 1954. Building P51s in quantity in 1941 means either pausing building something else, with a significant hiatus in deliveries, or drawing in extra US funds to rapidly build new plants, new materials and components, recruit and train new labour etc. at a rate at least comparable to the actions taken in 1942 after being forced into the war. One might note that in 1942 US fighter squadrons in North Africa, and later in Italy, were arming themselves with British built Spitfires which otherwise would have been arming RAF fighter squadrons. As for the B29, one only has to look at the enormous costs associated with establishing mass production when it was decided to spend a fortune on the B29. Not to mention the questionable state of development of the engines in 1941. I would not want to be a politician arguing the case for the extra giant funding for a war in which the USA was just a spectator.

These were fine aeroplanes when they arrived and did fine work but having them in useful production in 1941 is questionable. Politically in finding the funding, in engineering to have them ready with their engines up to standard and operationally in being enough to replace the OTL aeroplanes.

For the B29 with a decision in 1940, ideally 1939, where would one expect to base them and against what targets? There was nowhere within range of Japan. The B29, excellent though it was, was no B36 capable of transatlantic missions from the USA.

The only conceivable enemy at the time was Germany or Japan. So for Germany it would need bases in Britain or Egypt at best. Neither had spare suitable airfields capable of taking the B29. It would mean investing in a whole regime of foreign airfield construction with all the costs and resource that implies and to do so when the USA was not at war. Not to mention the implications for maintaining neutrality.

In the Pacific the furthest forward would be the Philippines. IOTL once the USA was forced into the war then the solution was to throw money at the problem and a series of hard fought campaigns to seize islands close enough to reach Japan. Indeed generally to throw money at the problems. The results were both expensive and remarkable and not only by the USA. Basing strategic US bombers In Britain caused the already stretched UK construction industry, in the midst of its century's largest construction project, to then build a huge extra number of large airfields to launch strategic heavy bomber raids against Germany. They then went on to build even more for the US strategic bombers. IOTL for the B17/24 of comparable weight and demands. But B29s means stronger and longer runways. Already Lincolnshire and East Anglia had airfields so close together that their circuits all but interlocked.

In the context of a peacetime economy the P51 was capable, with brave and determined decision making, of being made early in quantity and at the short term expense of fighter deliveries by making it the sole USAAF fighter turning new and existing factories over to it. It was mature enough to be ready for this and could use either the Allison or Packard Merlin IOTL put into the P40 or P39. The B29 was not so ready and one might find a manned turreted B23 á more suitable choice for an earlier introduction, but that latter is for another thread I think but the B29 was not necessary until the islands to base them were taken.

Overall there is much merit in bringing the P51 into service as the standard fighter earLy but the B29 not so much. In the given peacetime context I have severe doubts whether either would be politically possible due to political in fighting and the sheer government cost and lack of powers and will of government direction of industry that Britain had as a working wartime economy. Those many with a better knowledge of the political situation in the USA in 1940/41 can doubtless advise and correct me further.