What if America built De Havilland Mosquitoes instead of the B-17 Flying Fortress?

[SaparotRob]

Ya' got that right! I was very impressed when told it had "Battle Reverse". A few months ago I found a YouTube vid on them. First time a YouTube story agreed with personal experience.

 

[wuzak]

In terms of production, making enough Mosquitoes to be used as a strategic bomber was not a problem. Making enough bomber type Mosquitoes was the problem, with the FB.VI being the most produced model.

 

[GrauGeist]

I do kind of like the A-36 for use in the Pacific (not just in China) but that is a separate discussion for another time.

Just a quick side note about this:
The SBD (and later, TBF/TBM) was the champ for that role in the PTO.
They had the range needed fir the task.

The A-36 ruled for land ops where the SBD (and again, the TBF/TBM) were impractical to be used (except in North Africa, courtesy of the USS Ranger of course).

 

[Schweik]

Just a quick side note about this:
The SBD (and later, TBF/TBM) was the champ for that role in the PTO.
They had the range needed fir the task.

The A-36 ruled for land ops where the SBD (and again, the TBF/TBM) were impractical to be used (except in North Africa, courtesy of the USS Ranger of course).

The SBD worked extremely well in the hands of Navy pilots, as we know, but it seems to have proven vulnerable and not nearly as deadly accurate with Marine pilots, and had a fairly dismal record with Army pilots as the A-24 for example when used in New Guinea. I think it required a lot of training to reach it's full potential, and it was also pretty slow. I see the A-36 as potential rival in the role of land (island) based dive bomber, which could sink ships and also attack land targets, but would at least in theory be fast enough to pretty easily evade Ki-43s and A6Ms.

I think it could have had a niche for a while anyway.

 

[Schweik]

In terms of production, making enough Mosquitoes to be used as a strategic bomber was not a problem. Making enough bomber type Mosquitoes was the problem, with the FB.VI being the most produced model.

Couldn't FB type Mosquitos or say, MK IV types also do the job? Sincere question as I am admittedly not an expert on the Mossie

 

[Schweik]

About 360, if I remember correctly.

This might give you a sense of it (just part of the Holy Roman Empire circa 1400)

https://www.allaboutlean.com/wp-content/uploads/2014/09/Map-Europe-1400.png

 

[wuzak]

Couldn't FB type Mosquitos or say, MK IV types also do the job? Sincere question as I am admittedly not an expert on the Mossie

FB type Mosquitoes were slower, as the flat windscreen was draggier,

The cannon installation also took up half the bomb bay area, so internal bomb bay was restricted to just 2 500lb bombs. Two more could be carried on underwing pylons.

The Mk.IV was a bomber type. It could do the job, but less margin than the B.IX and B.XVI. Its normal load was 4 x 500lb, it could carry the 4,000lb bombs, but was not the best. I do not think any B.IVs received the universal wing, which was introduced with the FB.VI, so would be unlikely to be able to carry wing bombs or drop tanks.

The B.IX and B.XVI could carry 5,000lb for shorter trips - 1 x 4,000lb + 2 x 500lb. Or it could carry 6 x 500lb. Or 1 x 4,000lb + 2 x 50UKG drop tanks. They had maximum speed and continuous cruising speed roughly 30-40mph faster than the B.IV.

But it depends on what "the job" was.

 

[Schweik]

Right well presumably they would adapt it to the circumstances they encountered. This is a 'what if' so we can only take it so far, but I think it had the potential to do the job.

Do you have a performance breakdown (or at least speed) of the different types?

 

[GrauGeist]

The SBD worked extremely well in the hands of Navy pilots, as we know, but it seems to have proven vulnerable and not nearly as deadly accurate with Marine pilots, and had a fairly dismal record with Army pilots as the A-24 for example when used in New Guinea. I think it required a lot of training to reach it's full potential, and it was also pretty slow. I see the A-36 as potential rival in the role of land (island) based dive bomber, which could sink ships and also attack land targets, but would at least in theory be fast enough to pretty easily evade Ki-43s and A6Ms.

I think it could have had a niche for a while anyway.

The Marines' combat debut (Midway) was due to not following USN training.

The USAAF's early deployment of the A-24 was flawed and as a result, saw a re-examination based on USN tactics, leading to better training for A-36 pilots and it proved dividends many times over.

 

[Schweik]

Plus A-36 was about 100 mph faster which helps in not getting shot down. They managed to use them pretty successfully in a very, very high threat environment in Italy.

 

[wuzak]

Do you have a performance breakdown (or at least speed) of the different types?

I would have thought that would be knowledge necessary to form an opinion on this what-if.

 

[ThomasP]

re Mossi speeds

B Mk IV 360/380 mph at 9,000/14,000 ft, ROA with 4x 500 lb bombs ~700 miles
B Mk IV big belly mod, ROA with 4000 lb bomb ~600 miles
B Mk IX 386/408 mph at 13,000/26,000 ft, ROA with 4x 500 lb bombs & 2x 50 Impgal DT ~700 miles
B Mk IX big belly mod, 376/397 mph at 13,000/26,000 ft, ROA with 4000 lb & 2x 500 lb bombs ~500 miles

NOTE that most economical cruise for range was ~265/245 for the normal/big belly types and max economical cruise was ~320 mph, all at ~15,000 ft for both types

re accuracy from lower altitude

By 1939-40 the USAAF average CE using the Norden bombsight was 400 ft during training exercises, at 15,000 ft bombing altitude and in clear weather, flying straight line as long as needed to line up properly. According to data from training and practice bombing, a heavy bomber at 20,000 feet had a 1.2% probability of hitting a 100-foot-square target. About 220 bombers would be required for 90% probability of destroying the target.

By 1939 the USN considered the Norden usable against stationary ship size targets from 10,000 ft maximum.

Basically, before the US entered the war and despite all the propaganda to the contrary, the US high command knew it could not precision bomb targets.

 

[Stig1207]

A question: do the Germans react to a large number of small raids with Mosquitoes with the same urgency as a small number of large raids by heavies?

It is unlikely that they would react in the same way as they did against the USAAF daylight heavy bomber campaign; there would be little point in moving fighter units from the Eastern Front and the MTO to Germany if there was little chance of intercepting these raids. Rocket armed Zerstorer and twin engined nightfighters in daytime won't be of any use either; so the Jagdwaffe may in fact be spared considerable attrition.

 

[drgondog]

FB type Mosquitoes were slower, as the flat windscreen was draggier,

The cannon installation also took up half the bomb bay area, so internal bomb bay was restricted to just 2 500lb bombs. Two more could be carried on underwing pylons.

The Mk.IV was a bomber type. It could do the job, but less margin than the B.IX and B.XVI. Its normal load was 4 x 500lb, it could carry the 4,000lb bombs, but was not the best. I do not think any B.IVs received the universal wing, which was introduced with the FB.VI, so would be unlikely to be able to carry wing bombs or drop tanks.

The B.IX and B.XVI could carry 5,000lb for shorter trips - 1 x 4,000lb + 2 x 500lb. Or it could carry 6 x 500lb. Or 1 x 4,000lb + 2 x 50UKG drop tanks. They had maximum speed and continuous cruising speed roughly 30-40mph faster than the B.IV.

But it depends on what "the job" was.

Wuzak, the focus of the alternative universe is the ability of the Mosquito (any version) could duplicate B-17 Strike radius with ear duplicate range - and useful payload combination. In my mind, one precision delivered 2000# GP might be worth several B-17s (or more depending on comparisons of bombing via Mickey through 10/10 cloud cover). If a squadron of Mossies could penetrate at low altitude to Ploesti or Brux specific targets (like Cat cracker, platformer, etc) with 2000 pound bombs, with acceptable losses - I am more interested in the discussion. That said, the next question is 'Why weren't the RAF substituting fewer Mossies for many more Lancasters on a routine basis for much shorter range targets like Misburg?

Without doing the math, To me the 'job' was 100' CEP for 50% of the planned specific target(s) for 2x1000 pound bombs - with clear visibility at any altitude chosen to compare against large force B-17/B-24 attacks. Presumed that only low altitude bombing fits the spectrum of accuracy attainment for Mosquito. RAF demonstrated such capability. In 10/10 cloud cover the advantage of small force of Mosquitos over large forces of B-17s seem to favor the Mosquito unless the target is well defined contrast (harbor, lake, etc)

I just can't see any scenario of medium to high altitude, long range, daylight attacks in which the Mossie is a better choice. Begs the questions ' what were Mosquito bomb aiming advantages over AAF doctrine at long range, what were acceptable loss rates for basically unarmed Mosquitos in daylight operations deep into Germany or Rumania, and what were crew/aircraft replacement considerations?

 

[drgondog]

re Mossi speeds

B Mk IV 360/380 mph at 9,000/14,000 ft, ROA with 4x 500 lb bombs ~700 miles
B Mk IV big belly mod, ROA with 4000 lb bomb ~600 miles
B Mk IX 386/408 mph at 13,000/26,000 ft, ROA with 4x 500 lb bombs & 2x 50 Impgal DT ~700 miles
B Mk IX big belly mod, 376/397 mph at 13,000/26,000 ft, ROA with 4000 lb & 2x 500 lb bombs ~500 miles

NOTE that most/max economical cruise for range was ~265/245 for the normal/big belly types and max economical cruise was ~320 mph, all at ~15,000 ft for both types

re accuracy from lower altitude

By 1939-40 the USAAF average CE using the Norden bombsight was 400 ft during training exercises, at 15,000 ft bombing altitude and in clear weather, flying straight line as long as needed to line up properly. According to data from training and practice bombing, a heavy bomber at 20,000 feet had a 1.2% probability of hitting a 100-foot-square target. About 220 bombers would be required for 90% probability of destroying the target.

By 1939 the USN considered the Norden usable against stationary ship size targets from 10,000 ft maximum.

Basically, before the US entered the war and despite all the propaganda to the contrary, the US high command knew it could not precision bomb targets.

ThomasP. As noted in some of my posts on this subject, my primary question regarding Mosquito replacement of USAAF Daylight Mission in ETO is "What is the selected attack/mission profile of a Mosquito with say, only one 2000 pound bomb?" Further, if Daylight missions considered feasible, what were the feasible CEP for the Mosquito at attack altitudes much greater than SL? Bomb aiming capability for 400' CEP for say 15,000 feet above most Flak battery accurate slant ranges?

Is the profile limited to low altitude strikes during daylight? What nav/bomb aiming combination required to hit the southeast corner of a building in a refinery complex (day or night) with CEP of even 400 feet at any altitude at 350mph? Are there RAF sources explaining that the Mosquito was being considered for high value precision targets at the ranges we are discussing for the Oil Campaign?

I don't believe that the phrase " the US high command knew it could not precision bomb targets." is strictly correct.

As to the B-17/Norden question. The poor bombing accuracy achieved by 1942 8th AF was a shock, not a resignation due to preset peacetime achievement expectations. I don't have any problem with your cited statistics, but note that CEP data is largely macro - including all ranges of visibility conditions ranging from clear to 10/10 undercast.

Curtis LeMay recognized early that established peacetime doctrine of acceptable training and formation structure fell short of mission requirements in the ETO. The crafting of combat box formations to 'shrink' the footprint of the formations, selecting lead crews and carefully prepared target portfolios for IP and Bomb Aiming planning, removing ability of pilot to take evasive manuevers via AFE slaved to bombsight - were all major improvements over peacetime training. Other processes like 'bombing in synch with lead crews were also major improvements to overall squadron accuracy.

 

[wuzak]

Wuzak, the focus of the alternative universe is the ability of the Mosquito (any version) could duplicate B-17 Strike radius with ear duplicate range - and useful payload combination.

Not all Mosquito versions could deliver the required bombs.

Night-fighters couldn't, PR versions couldn't, though they were closely related to the bomber versions. And fighter-bombers (the FB.VI) couldn't, owing to the cannons protruding into the front half of the bomb bay.

No Mosquito could match the very long range missions that B-17s (or Lancasters) could do. The maximum radius is roughly to Berlin, perhaps a little past.

In my mind, one precision delivered 2000# GP might be worth several B-17s (or more depending on comparisons of bombing via Mickey through 10/10 cloud cover).

The British did not have a suitable 2,000lb bomb. The best they had was the older 1,900lb GP bomb, which had about as much explosives as the 1,000lb MC bomb.

The US 2,000lb GP bomb would need to have its tail modified to the British style.

In development the Mosquito was trialed with 1 x 1,000lb GP (older type with low charge-to-weight ratio) and 2 x 500lb MC. But this arrangement was never used, It required slight modifications to the bomb bay doors. The 1,000lb MC was bigger diameter, so would have needed modified doors, though not quite as large as the eventual bulged doors.

When the Mosquito did start using the 1,000lb MC bomb it used the carrier for the 4,000lb bomb, and only one could be carried. More often used was the 1,000lb Target Indicator, which was the same size and shape as the 1,000lb MC. 627 Squadron, IIRC, did make an adapter to take two 1,000lb MC bombs. These all required the bulged bomb bay.

From early 1944 Mosquitoes modified with the bulged bomb bay door and carrier could carry the 4,000lb bombs. The IV could, but it was marginal. The IX and XVI were much better at it.

There were at least two 4,000lb bombs the Mosquito could accommodate - the 4,000lb High Capacity (HC) "cookie" and the 4,000lb Medium Capacity (MC) bomb. There may have also been a 4,000lb Incendiary bomb, but I can't confirm that. I assume that if a 2,000lb bomb works, then a 4,000lb would be better.

The British MC bombs were similar to the American GP bombs in size and charge-to-weight ratio.

In terms of penetrating at low level, I think that the B.XVI would be better flying at high altitude to close to the target, then dive to low level for the attack and then climb again for the return journey. That should give better range and plays to the B.XVI's strength.

If a squadron of Mossies could penetrate at low altitude to Ploesti or Brux specific targets (like Cat cracker, platformer, etc) with 2000 pound bombs, with acceptable losses - I am more interested in the discussion.

Ploesti was out of reach for Mosquitoes until Italy fell. Basically when P-38s could reach Ploesti so could Mosquitoes.

Brux may have been possible for Mosquito B.XVIs flying at mid-to-high altitude carrying a 4,000lb bomb with 2 x 50UKG drop tanks. Could be at the outer edge of their radius, and probably would have to sacrifice some speed on the outward and return journeys to get the extra range.

I did a calculation many of years ago that suggested a B.IV, if it could be fitted with drop tanks*, would be very close to being able to fly to Schweinfurt at 0ft the whole trip.

*B.IVs didn't have drop tank facilities, but could have if production continued.

That said, the next question is 'Why weren't the RAF substituting fewer Mossies for many more Lancasters on a routine basis for much shorter range targets like Misburg?

I am guessing priorities.

When production orders were being put in for the Mosquito the emphasis was on attacks on cities, for which the Mosquito was ill suited. So bomber Mosquitoes were lower priority than the other variants.

And their main job, to start with, was as pathfinders for the heavies, using Oboe and Gee-H.

In 1944 the Light Night Striking Force was formed. They did Mosquito-only raids, often as diversions for Lancaster raids, drawing the German night-fighter defences away from the main attack areas.

Without doing the math, To me the 'job' was 100' CEP for 50% of the planned specific target(s) for 2x1000 pound bombs - with clear visibility at any altitude chosen to compare against large force B-17/B-24 attacks. Presumed that only low altitude bombing fits the spectrum of accuracy attainment for Mosquito. RAF demonstrated such capability. In 10/10 cloud cover the advantage of small force of Mosquitos over large forces of B-17s seem to favor the Mosquito unless the target is well defined contrast (harbor, lake, etc)

I think that in bad weather the Oboe and, more particularly, Gee-H systems were more accurate than H2S/H2X. However, the range was restricted, though further than Lancasters could use the system.

Visual bombing from 30,000ft was probably less accurate for the Mosquito than the B-17 because of the higher speed and lesser stability. Also, the bomb sight - most Mosquitoes used the Mk XIV. The Norden sight was not well suited to the Mosquito.

I just can't see any scenario of medium to high altitude, long range, daylight attacks in which the Mossie is a better choice. Begs the questions ' what were Mosquito bomb aiming advantages over AAF doctrine at long range, what were acceptable loss rates for basically unarmed Mosquitos in daylight operations deep into Germany or Rumania, and what were crew/aircraft replacement considerations?

Acceptable loss rates I guess would be dependent on results. With good tactics for daylight bombing I would think the loss rate would be sustainable - production rate and crew training would compensate for losses.

Crew replacements would, in one way, be easier than for B-17s, as there are two crew instead of 10. The other side of that is the crew required are the highest trained - the pilot and navigator/bomb aimer/radio operator (though in low level attacks it was typically the pilot that did the bombing).

With US and Commonwealth training schemes there should be enough of both. Didn't the USAAF have two sets of crew, or nearly so, for every bomber in England by the end of the war?

 

[wuzak]

Is the profile limited to low altitude strikes during daylight? What nav/bomb aiming combination required to hit the southeast corner of a building in a refinery complex (day or night) with CEP of even 400 feet at any altitude at 350mph? Are there RAF sources explaining that the Mosquito was being considered for high value precision targets at the ranges we are discussing for the Oil Campaign?

At low level mosquito fighter-bombers were able to place bombs into a corner of a building in the middle of a city. Is that good enough?

The aircraft doesn't have to fly the whole route at low level. For longer range targets it would be necessary to get the range.

 

[swampyankee]

While I think it's likely that the heavy defensive firepower* of US heavy bombers increased casualties, as those very guns increased the size of each bomber's aircrew, reduced its bomb load, and increased the number of sorties required, I don't think Mosquitoes (or a comparable US aircraft) would be able to inflect the sort of damage as a mass of B-17s (or B-24s) without adopting many of the same tactics, that is massive formations dropping bombs based on a signal from a lead bombardier. They'd also be suffering the same lost rate due to AAA, as they would be constrained to the same long straight and level path prior to bomb delivery. There may be lower losses on the flight to the target, as they may be able to cruise at higher speed**, and on the return flight, as their superior speed may result in lower losses, as the aircraft may be much less vulnerable out of formation than in.

--

* Of course, no number of 0.5 in machine guns at 20,000+ feet will be particularly effective against AAA.

** I suspect that WW2 era navigation technology would make it impractical to have a large number of aircraft cruise independently to a rendezvous point and form up into the mass formations so beloved of day bomber generals.

 

[wuzak]

re Mossi speeds

B Mk IV 360/380 mph at 9,000/14,000 ft, ROA with 4x 500 lb bombs ~700 miles
B Mk IV big belly mod, ROA with 4000 lb bomb ~600 miles
B Mk IX 386/408 mph at 13,000/26,000 ft, ROA with 4x 500 lb bombs & 2x 50 Impgal DT ~700 miles
B Mk IX big belly mod, 376/397 mph at 13,000/26,000 ft, ROA with 4000 lb & 2x 500 lb bombs ~500 miles

NOTE that most economical cruise for range was ~265/245 for the normal/big belly types and max economical cruise was ~320 mph, all at ~15,000 ft for both types

re accuracy from lower altitude

By 1939-40 the USAAF average CE using the Norden bombsight was 400 ft during training exercises, at 15,000 ft bombing altitude and in clear weather, flying straight line as long as needed to line up properly. According to data from training and practice bombing, a heavy bomber at 20,000 feet had a 1.2% probability of hitting a 100-foot-square target. About 220 bombers would be required for 90% probability of destroying the target.

By 1939 the USN considered the Norden usable against stationary ship size targets from 10,000 ft maximum.

Basically, before the US entered the war and despite all the propaganda to the contrary, the US high command knew it could not precision bomb targets.

If that data is from the Data Sheets then I believe that the economical cruise numbers is the most economical at 15,000ft, not that 15,000ft was the altitude for maximum economical cruise range.

From the Mk VIII, IX and XVI Operational Performance notes.

So 20,000ft was better for economical cruise for the IX and XVI.

And for maximum continuous cruise, the best altitude was 30,000ft.

 

[wuzak]

While I think it's likely that the heavy defensive firepower* of US heavy bombers increased casualties, as those very guns increased the size of each bomber's aircrew, reduced its bomb load, and increased the number of sorties required, I don't think Mosquitoes (or a comparable US aircraft) would be able to inflect the sort of damage as a mass of B-17s (or B-24s) without adopting many of the same tactics, that is massive formations dropping bombs based on a signal from a lead bombardier. They'd also be suffering the same lost rate due to AAA, as they would be constrained to the same long straight and level path prior to bomb delivery. There may be lower losses on the flight to the target, as they may be able to cruise at higher speed**, and on the return flight, as their superior speed may result in lower losses, as the aircraft may be much less vulnerable out of formation than in.

--

* Of course, no number of 0.5 in machine guns at 20,000+ feet will be particularly effective against AAA.

** I suspect that WW2 era navigation technology would make it impractical to have a large number of aircraft cruise independently to a rendezvous point and form up into the mass formations so beloved of day bomber generals.

The Germans could see, with radar, a raid starting as the bombers climbed into position and formed up over England.

RAF bombing raids tended to not do that, not the least because having all the aircraft circling around waiting to form up was a disaster waiting to happen at night.