RAF daylight strategic bombing campaign results

[mhuxt]

Of the Mosquito-only raids, the majority took place when the heavies were at home. Any number of Mossies came home "on one", can't agree that the ones that didn't account for most cases. During the daylight raids of '42-'43, overall Mossie loss rates dropped appreciably when they went low-level. Losses to flak went up slightly - if the loss rate to flak had stayed even, the Mossie squadrons could have expected to lose 11.5 aircraft, when in fact they lost 13.

 

[kool kitty89]

It goes back to what you had for available bombers and try to compare them to the American bombers of 1942/43. The American bombers had engines with turbos that would give 1000hp max continuous to 27,000ft or above and they weren't good enough to keep 4 engine bombers doing 200+mph at altitudes over 20,000ft in large formations. Mainly because by the time you get to max cruise lean you are down to around 750hp. The Melrin XX wasn't much different. Max lean cruise was around 725-760hp depending on altitude (and without the turbo that was down around 18-20,000ft). Problem for the Melrin XX is that as you go above 18-20,000ft the cruise power drops. The B-17 could hold 750hp cruise to 35,000ft. Makes cruising at 24-26,000ft a breeze.

Perils P40 Archive Data

The V-1650-1 is listed at econimical cruise of 2650 RPM 725 hp, low blower, auto-lean at 20,000 ft. (not too much less than the max cruise power at 2320 RPM ... but I suspect British and american standards for maximum cruise might differ a bit)

Also odd that the minimum specific consumption on the merlin is at high RPM, it's certainly not the case on the allison. (granted, minimum specific consumption and most economical power settings for a given aircraft are different matters, but still that's much different from the cruise figures for the V-1710) ... and reading the figures more closely shows 'maximum cruise' at 2,320 rpm high blower 18,000 ft having significantly more power and LOWER fuel consumption than at 2,650 20,000 ft ... so the labeling of those cruise power settings seem a bit odd.

The USAAF chart also leaves a big gap between 20k and 30k ft, but given 20k is still in low blower (while 30k is in high if only 580 hp) that still implies a bit of room for variables there. (though running at lower RPM in high supercharger gear seems to make the most sense in the 20,000 ft range too)

So the interim solution seems to be, use bombers that have lousier gun defense than the Americans used, bombers that can't fly any faster, bombers that can't fly as high, and bombers that can't (if you try for high altitudes) carry much more than the American bombers. And use escort fighters that had trouble matching the German fighters over the coastal areas without being burdened with long range fuel tanks. Why the panic over getting MK IX Spits in service? Because the MK Vs couldn't to the job and yet somehow adding several hundred pounds of tanks and fuel will improve the combat results?

How much does this comparison differ from the experiences with Luftwaffe precision day bombing during the BoB? (aside from them having no real heavy bombers, though several of the medium bombers were higher performing and/or better armmed)

Hmm, actually the He-111H series with 7 defensive guns during the BoB seems better covered than the british heavies, let alone the later H models with improved armaments. (given the relative sizes, more akin to the B-17's defensive arrangement ... or B-25's )

Lack of waist and ventral guns on british heavies leaves a lot of open spots. (wellington too)

I don't think higher than 20000ft is needed in 1941/42 in fact if only Allison engined escorts are available I was thinking as low as 15000ft for bombers since fighters could provide top cover at about 20000ft before being forced down to 15000ft where the bombers they were protecting were (Allison's full throttle height). At 15000ft bombers are more vulnerable to FLAK but the numbers of guns and numbers of radar was nowhere near as high as it would become and fighters are far more dangerous.

They would have been capable of some very accurate bombing over the highly industrialised Ruhr in the summer and fall of 1941.

If the Merlin XX is available for the escorts then Attack altitude over 20000ft would seem to be practical.

Mustang IIs (9.6 supercharged allisons) might have been good enough to provide top cover for bombers cruising at 20,000. Or ... better than overweight spitfire Vs (spit IXs with extended fuel capacity would be another matter). Speed was the big disadvantage of the Spitfire V next to the 190s, and the P-51A fared much better there even at 20,000 ft.

But ... historical Mustang IIs (and P-51As) came too late to be useful anyway and too few with the Mustang III coming online very soon after. (a hypothetical V-1650-1/Merlin XX powered mustang I alternative is another matter though)

But aside from that, long-range spitfire models with expanded fuel and streamlined armaments seem the most practical option. Merlin powered P-40s were too heavy and also a bit late into service anyway ... and arguably worse than the historical Mustang I/Ia even with the limited power at altitude.

It is common to quote losses in percentages. However losses are in aircraft which have to be replaced. I doubt that any group of 10 bombers (4 engined heavies) trying to raid deep into Germany at any time during the war in daylight would suffer less than 60% losses and would probably be 100% more often than not. You need a massive number of bombers and escorts to keep the losses down to 10%. The UK had just staggered through the BoB in 1940 , I think it is very very fanciful (as some have) to think about forces of 500 x 4 engined bombers and escorts in 1941 when we were struggling to cope with defence of the UK plus N Africa.

Wouldn't this be another argument in favor of focusing on shorter/medium range bombing objectives? (more like the RAF already was, just with the shift to daylight precision bombing)

The Mustang was an Accident, not clever planning, and forever linked to the idea of "P-40 replacement" for low to medium altitude utility fighter. The Wing Rack and Fuel drop tank ideas first originated with the notion of keeping the NAA Mustang line (and plant and workers) employed by slipping the A-36 procurement into available AAF Dive Bomber funding in early 1942. The notion of Merlin engine modification originated with RR in the last days of April, 1942.

A lot of this was also just looking for middle ground though. Not something as good as the mustang, just something closer to what the P-47C, P-40, or even P-39 could manage in 1941/42. (except not the P-47 since it wasn't combat ready yet, let alone in sufficient numbers) Or for that matter, similar to the P-38 or P-51/Mustang I's combat radius without drop tanks.

The RAF didn't need a 'long' range fighter in the USAAF sense for this scenario ... just a normal/medium range one rather than the short range aircraft they actually had in force.

Basically the practical radius of a standard typhoon was closer to 250 miles if you count the combat allowance and provide a decent reserve.

Yes, which is why I brought it up with the specific context of expanding internal fuel capacity as well.
And given the timing of the Mustang and Spitfire IX, a medium/long range Tempest might still have been useful. (Spitfire IX with expanded fuel capacity would probably the main target though)

 

[wuzak]

2,650rpm, +7psi boost was the maximum continuous (cruise) power of later Merlins.

 

[Shortround6]

knocking an engine out at 20,000 ft gives the pilot a problem but knocking an engine out at 50ft is a kill in most cases

Any number of Mossies came home "on one", can't agree that the ones that didn't account for most cases.

Mossies are NOT most cases. Try loosing an engine on a Blenheim, Hampden, or Wellington at 50ft and see what the odds of surviving are. And those three aircraft made up the bulk of bomber Commands aircraft in 1941 and for a good part of 1942.
Hopefully nobody was thinking of sending Whitleys on low level missions, the other 1941 mainstay.

Some (many) of the early twins didn't have feathering propellers so a 'dead' engine was real problem. Prop could only be set to max pitch (if the prop control worked) and pilot/crew hoped for the best.

 

[Greyman]

Hmm, actually the He-111H series with 7 defensive guns during the BoB seems better covered than the british heavies, let alone the later H models with improved armaments.

Lack of waist and ventral guns on british heavies leaves a lot of open spots. (wellington too)

The Wellington (Ia) had a retractable mid-under turret (though it was quite unsatisfactory) and a port/starboard .303 in each side (Ic on).

The firing arcs of the mid-upper turrets of the four-engined heavies were capable of covering the sides.

Mid-under turrets were fitted to the Stirling, Halifax and Lancaster - but these didn't last long as they weren't very useful at night.

The German bombers' defensive armament had a few shortcomings - one can't merely count the barrels.

• hand-held on gimbal mountings: much more difficult to fire steady, accurate bursts than weapons mounted in a powered turret
• magazine-fed: every 75 rounds the gunner has to change magazines, as opposed to the 500 to 2,500 rounds belts the British turrets used
• ring-and bead sights

 

[Shortround6]

How much does this comparison differ from the experiences with Luftwaffe precision day bombing during the BoB? (aside from them having no real heavy bombers, though several of the medium bombers were higher performing and/or better armmed)

Hmm, actually the He-111H series with 7 defensive guns during the BoB seems better covered than the british heavies, let alone the later H models with improved armaments. (given the relative sizes, more akin to the B-17's defensive arrangement ... or B-25's )

You have got to be joking?
Most He-111s were lucky they had six guns let alone seven. The idea that a single gun (1000rpm) with a 75 round magazine manually aimed on a pivot mounting was the equal of 2 or 4 guns (11-1200rpm) with belt feeds and powered mountings is quite a stretch. That fixed gun in the tail of the He 111 did a to of good too. Mostly for morale of the bomber crew. Didn't stop others from trying it. He 111 didn't get a powered (if you could call it that) top turret until 1942.

Lack of waist and ventral guns on british heavies leaves a lot of open spots. (wellington too)

British tail turrets had a pretty wide field of fire, usually much larger than most early US tail positions.

The best (easiest to aim) firing position was dead astern. the more around to the sides you get the more deflection (lead) was needed and the more difficult the firing solution became.

But basically it comes down to if the American bombers with 9-13 .50 cal mounts with 2-4 powered mounts couldn't defend themselves then how does 6-10 .303 guns with 2-3 powered mounts look like it's going to work?

Mustang IIs (9.6 supercharged allisons) might have been good enough to provide top cover for bombers cruising at 20,000. Or ... better than overweight spitfire Vs (spit IXs with extended fuel capacity would be another matter). Speed was the big disadvantage of the Spitfire V next to the 190s, and the P-51A fared much better there even at 20,000 ft.

Speed only counts for so much, once you have done a couple of 180 turns speed and/or altitude has bled off considerably. Now you need acceleration/climb to get back in the game. This is one reason the British passed on the P-40s in late 1940 and early 41 compared to the Hurricane. They were faster but once speed was bled off in the first few maneuvers they were headed for being sitting ducks.

 

[mhuxt]

Mossies are NOT most cases.

That's fair enough - I had thought the reference was specifically to >twitch< Mosquitos >twitch<

 

[pbehn]

Of the Mosquito-only raids, the majority took place when the heavies were at home. Any number of Mossies came home "on one", can't agree that the ones that didn't account for most cases. During the daylight raids of '42-'43, overall Mossie loss rates dropped appreciably when they went low-level. Losses to flak went up slightly - if the loss rate to flak had stayed even, the Mossie squadrons could have expected to lose 11.5 aircraft, when in fact they lost 13.

I am not twisting your tail mhuxt and I am a great admirer of the Mosquito. From when the Mosquito was introduced BC had already switched to night bombing. The mossie made many famous precision raids but total production for all types was 7,781 compare to 7377 Lancasters 6176 Halifaxes. To use the Mosquito as a strategic weapon may have been possible in hindsight but only in hindsight, to use the Mossie in such a role would need the decision to be made before the aircraft was even designed. I know many mosquitos came home on one engine, many four engined AC came home on three or even two but they didnt lose the engine while under fire 50ft from the ground. If the RAF had committed to a force of mosquito types then the LW would have committed to a response. Many of the famous mossie raids were against places like Oslo, Copenhagen and a Berlin Radio station and a French prison. I am not knocking the raids or the people involved at all but it was a different matter to hit properly defended targets. I doubt if the LW considered Gestapo headquarters or prisons to be targets at all or at least until a few were hit.

The thread is about RAF daylight bombing in 1941/42 the mosquito could hardly figure in any meaningful sense until 1943, my original comments concerned RAF bombers other than the mosquito used in low level raids. I had in mind the Lancaster raid on Augsburg April 1942 which was heavily hit by interceptors and flak and never repeaded because a Lanc is not a mosquito.

 

[mhuxt]

I am not twisting your tail mhuxt

No worries, heheheh my post was mostly Pavlovian: "Gack! Discussion mentioned Mosquito! Must ... post ..."

 

[wuzak]

The low level raid against Augsburg by Lancasters was a disaster, but the raid against Cruesot was successful.

As posted earlier in the thread: 17th October 1942: Operation Robinson hits Le Creusot works

It maybe the size of the attack had some bearing - the Augsburg raid was smaller.

 

[Greyman]

The low level raid against Augsburg by Lancasters was a disaster, but the raid against Cruesot was successful.

It maybe the size of the attack had some bearing - the Augsburg raid was smaller.

I think it was because there was a navigation/planning error and a portion of the Augsburg formation flew directly over a Luftwaffe fighter base.

 

[pbehn]

The low level raid against Augsburg by Lancasters was a disaster, but the raid against Cruesot was successful.

As posted earlier in the thread: 17th October 1942: Operation Robinson hits Le Creusot works

It maybe the size of the attack had some bearing - the Augsburg raid was smaller.

I agree but Augsburg is in Germany Le Creusot is in Central rural France.

 

[pbehn]

I think it was because there was a navigation/planning error and a portion of the Augsburg formation flew directly over a Luftwaffe fighter base.

There were diversionary raids to support the attack, some LW aircraft returning to base saw the Lancs trying to sneak through. That was bad luck bu just a couple of LW fighters created havoc.

 

[Shortround6]

I believe the this was mentioned earlier in the thread. Le Creusot was just a few miles from Vichy France and part of the flight path may have crossed Vichy France. I am don't know what the flight path was but there is a photo of the formation flying over a small town near Tours which certainly suggests a roundabout route. Which is a perfectly good tactic, it just doesn't tell us how well that would have worked over Germany.

 

[stona]

The rout took the Lancasters around Brittany and over the sea down the Atlantic coast of France before they turned inland, crossing the coast north of La Rochelle. This meant that they only flew over a relatively narrowl tongue of the occupied zone that extended south to the Spanish border (to include France's important Atlantic ports and Bordeaux) before continuing the flight eastwards over Vichy France. The last way point, from which the climb to bombing height began, was Nevers. The raid was timed so that much of the return flight was made under cover of darkness.
It was quite a different operation to the attack on Augsburg, six months earlier. The British had learnt their lesson from that one. The next day light target was Milan, not Berlin
Cheers
Steve

 

[kool kitty89]

The Wellington (Ia) had a retractable mid-under turret (though it was quite unsatisfactory) and a port/starboard .303 in each side (Ic on).

The firing arcs of the mid-upper turrets of the four-engined heavies were capable of covering the sides.

Mid-under turrets were fitted to the Stirling, Halifax and Lancaster - but these didn't last long as they weren't very useful at night.

The German bombers' defensive armament had a few shortcomings - one can't merely count the barrels.

• hand-held on gimbal mountings: much more difficult to fire steady, accurate bursts than weapons mounted in a powered turret
• magazine-fed: every 75 rounds the gunner has to change magazines, as opposed to the 500 to 2,500 rounds belts the British turrets used
• ring-and bead sights

You have got to be joking?
Most He-111s were lucky they had six guns let alone seven. The idea that a single gun (1000rpm) with a 75 round magazine manually aimed on a pivot mounting was the equal of 2 or 4 guns (11-1200rpm) with belt feeds and powered mountings is quite a stretch. That fixed gun in the tail of the He 111 did a to of good too. Mostly for morale of the bomber crew. Didn't stop others from trying it. He 111 didn't get a powered (if you could call it that) top turret until 1942.

I'd actually been thinking more in terms of the B-17D's configuration when comparing the He-111 ... somewhat off topic given the 1941 British heavy bombers had much more stable gun placements, even if lighter guns. (and the turret equipped medium bombers) Not to mention nearly identical to the B-17C's armament, and the Fortress I didn't fare very well in RAF service. So the British were actually a good bit ahead in that respect.


But the Fortress I does remind me of another issue I keep forgetting to comment on: bombing accuracy. If the day bombers can't actually manage to hit precision targets on day raids, even if not shot down, that's a huge problem too. Bombing at higher and higher altitudes becomes problematic there, and the bombsights in use would be one of the deciding factors.

But basically it comes down to if the American bombers with 9-13 .50 cal mounts with 2-4 powered mounts couldn't defend themselves then how does 6-10 .303 guns with 2-3 powered mounts look like it's going to work?

The comments on armament are more towards 'being good enough to allow the escorts to be effective.' So limiting the options for attacking interceptors (and especially close-up attacks).

If the existing armament on 1941/42 heavy bombers (or medium bombers for that matter) could manage that, and manage a high enough altitude to avoid unsustainable losses from flack alone, and they could manage accurate bomblaying, then the deciding factor would be escorts.

 

[Shortround6]

And there you pretty much have your answer/s.

The comments on armament are more towards 'being good enough to allow the escorts to be effective.' So limiting the options for attacking interceptors (and especially close-up attacks).

RAF/Bomber Command pretty much turned away from Daylight attacks after the Fall of 1939 when they lost a number of planes trying to attack the German Warships in home ports. Granted the early Wellingtons did not have self sealing tanks and the early gun positions, while powered, didn't have the range of motion of the later turrets and the the tail position was only 2 gun. The 4 gun tail turret was introduced at some point in 1941 with somewhere between 1000-2000 (correction welcome) Wellingtons built with 2 gun tail turrets. For 1941 they would be the bulk of available bombers.

If the existing armament on 1941/42 heavy bombers (or medium bombers for that matter) could manage that.

The heavy bombers don't really show up until 1942. and then some are rather late. Lancaster, which seems to be every-bodies favorite had a total of 290 planes by the end of July 1942. That is NOT the number issued to units. that lags a few weeks or a few months.
There were only 202 Manchesters built and the less said about that the better.
The first several hundred Halifaxes had Merlin X engines. and this for performace;
http://www.wwiiaircraftperformance.org/Halifax/Halifax_I_ADS.jpg
There were under 150 Halifaxes built by the end of 1941.
One of the two main 4 engine type in 1941 and early 1942 was the Stirling. 2 gun turret in nose, 2 gun dorsal turret, two gun retractable belly turret and 4 gun tail turret. There was some variation between belly turrets, waist guns and top turrets on the very early planes.
And "Main" may give a wrong impression as it took until Early 1942 for a 3rd squadron to become operational on Stirlings.

and manage a high enough altitude to avoid unsustainable losses from flack alone

The Manchester, Stirling and early Halifax and most of the twin engine bombers were quite incapable of flying at anything near a high enough altitude while carrying both a high bomb load and large amount of fuel. Few of these planes had a service ceiling of over 20,000ft in full loaded condition and could only make 22-23,000ft by lightening the plane by around 10,000lb for the heavies.

Neil Stirling was kind enough to post some links to RAF data Sheets for many RAF twin engine bombers a while back.

Her are the links again.

http://www.ww2aircraft.net/forum/re...s://dl.dropbox.com/u/93074546/RAF%20Twins.rar

http://www.ww2aircraft.net/forum/re...dl.dropbox.com/u/93074546/RAF%20twins%202.rar

This should provide a base for estimating what could and could not be done by running planes light or changing engines to some extent (Hercules III s instead of Pegasus, etc)
Data cards for Halifax and Lancaster are at Spitfire performance. Short Stirling may be among the missing?

 

[EKB]

Of course long range missions in 1941 with escorts are essentially impossible unless the Spitfire V is properly prepared. The Spitfire carried around 90 Imp gallons of fuel in tanks behind the engine which gave a range of around 400 miles. Historically 2 smaller tanks were fitted in the wing leading edges (4 in all) which increased internal fuel tankage by around 33% and range of some marks of Spitifre VII and VIII by around 50% (600 miles) over the Spitfire IX which lacked it. This suggests to me escort radii with drop tanks of around 400-450 miles. Historically many spitfires also had tail tanks which tended to be regarded as ferry tanks only due to their destabilising effects in combat. However if only 10 gallons (instead of 44-50 gallons) I'm sure the effect would be minimal and further range increases would be possible.

Unfortunately there was another unresolved obstacle to flying long distance combat in British fighters. Nearly all Spitfires, including the Mk IX, had no cockpit heating system.

The canopy frosted up quickly at high altitude, especially during winter months. The pilot's oxygen tube often froze, causing the pilot to inhale ice crystals. There were more than a few complaints about the guns freezing. Cold weather was a deadly serious problem if the missions were extended from 90 minutes to five hours or more.

The long-range Spitfire PR Mk XI (circa 1944) had no guns and a crude cockpit heater that failed to stop icing and misting.

A good example of icing in the cockpit from Don Caldwell, The JG 26 War Diary: 1939-1942, p.307:

4th December 1942
" At 1410 the St. Pol Jäfu scrambled three Gruppen on reports that four formations were approaching the coast. These were RAF aircraft on Rodeo No. 115, a sweep of the Pas de Calais by twelve Spitfire squadrons. The all-Canadian Kenley Wing, flying its first mission as a wing, was having difficulty keeping formation, which is probably why it was the only unit seriously engaged.
Many of the Spitfire's canopies had frosted up in the minus fifty-degree temperatures, and few of No. 401 Squadron's pilots, flying as top cover, saw Hptm. Seifert's Focke-Wulfs dive through them over Marquise to attack No. 402 Squadron just as the wing turned at the end of its sweep. The Spitfires scattered in all directions, and before re-forming over Boulogne and withdrawing to England were attacked by Focke-Wulfs from the other Gruppen.
The pilots of the Geschwader claimed seven Spitfires; six of these claims were confirmed. The Canadians lost five Spitfires and three pilots; the only loss to the Geschwader was the damage one Third Gruppe FW 190 sustained while landing on Wevelghem with a blown tire. "

Casualties from Aircrew Remembered: world's premiere aviation personal history site

BATTERS Sgt Harold Mark From Portage La Prairie, MB, Born in 1921 Served w/ 401 Sqn On 4 Dec 1942 flying Spitfire F.IX BS277 for a sweep over the Pas de Calais, he is s/d by Fw-190 from JG 26 over Guines and KIA.

FIANDER P/O J.W. Served w/ 401 Sqn On 4 Dec 1942 flying Spitfire F.IX BS536 for a sweep over the Pas de Calais, he is s/d by Fw-190 from JG 26 over Guines. Rescued.

HONEYCOMBE Sgt R.B. USA From Brooklyn NY Served w/ 402 Sqn On 4 Dec 1942 flying Spitfire F.IX BS132 for a sweep over the Pas de Calais, he is s/d by Fw-190 from JG 26 over Guines and KIA.

McGRAW Sgt H.E. Served w/ 402 Sqn On 4 Dec 1942 flying Spitfire F.IX BS450 for a sweep over the Pas de Calais, he is s/d by Fw-190 from JG 26 and KIA.

NICKEL Sgt B.H. Served w/ 401 Sqn On 4 Dec 1942 flying Spitfire F.IX BS317 for a sweep over the Pas de Calais, he is lost near Audruicq possibly because of Oxygen failure and KIA.

SIMPSON F/O H.A. Served w/ 402 Sqn On 4 Dec 1942 flying Spitfire IX BS309 for a sweep over northern France, he is s/d and crash-lands at Hawkinge.

 

[gjs238]

Did any US WWII aircraft not have cockpit heaters?

 

[stona]

Unfortunately there was another unresolved obstacle to flying long distance combat in British fighters. Nearly all Spitfires, including the Mk IX, had no cockpit heating system.

You might want to check that.

Steve