Best medium bomber of WWII?

[fastmongrel]

What if it has a gun-nose and carries 4,000 lbs of bombs? What if the gun nose is made modular so you can swap it out in the field for a bombardier nose?

My point was it's a role not a function. A B25 with a battery of guns in the nose is carrying out light and tactical roles. A B25 with a glass nose, a bomb sight plus operator at 10,000 feet is carrying out a medium role.

I suggested the rule (I did say it was arbitrary and capricious) to try and stop people suggesting anything capable of lifting a bomb. After all a P47 and a Typhoon are getting towards pre war medium bomber numbers.

 

[Schweik]

So at Ploesti incidentally, the Russians sent their other types as well - DB 3, Il 4, which had much greater bomb loads. But they missed their targets and got shot down .

 

[Schweik]

My point was it's a role not a function. A B25 with a battery of guns in the nose is carrying out light and tactical roles. A B25 with a glass nose, a bomb sight plus operator at 10,000 feet is carrying out a medium role.

I suggested the rule (I did say it was arbitrary and capricious) to try and stop people suggesting anything capable of lifting a bomb. After all a P47 and a Typhoon are getting towards pre war medium bomber numbers.

Yes I agree it's difficult. And I'm not picking on you, just pointing out the limitations of the idea. The issue was in part that dropping bombs from 10,000 feet (or even 5,000 feet) often meant the bombs didn't hit the target.

But I agree with the nose guns it is certainly in a different role, which you could also call "attack" - it's still as an aircraft capable of both. (for example A-20 / DB 7 and B-25)

Then you have aircraft like the Beaufighter which didn't really carry many bombs but excelled in that 'attack' role, mainly as strafers.

 

[Dimlee]

For the PE-2 the bomb load was 600kg internal. Six 100kg bombs, two of which were the engine nacelles.
The 1000 kg load was external, four 250 kg bombs or two 500kg bombs
At which point speedand range depart from most published numbers.

You are right. But 1000kg was very rare. From my memory, the average bombload was even under 600 kg during most of the operations.

 

[Schweik]

500 kg in the examples I gave... and yet they operated with great success.

 

[Dimlee]

The Ki-48 and Ki-49 were also supposed to be highly agile, as was the Maryland and the Lockheed Hudson which survived some duels with A6M. Any other highly agile light or medium bombers I missed?

B7A? I just love this "Japanisch Stuka".
"Three B7A2s were captured at Kisarazu, in Chiba Prefecture, by US forces following the occupation of Japan and shipped to the US. One was sent to "Pax River" for evaluation by the US Navy and the remaining two were assigned to the USAAF. Flight testing revealed that the "Grace" possessed the handling and performance qualities of a fighter, being faster and more maneuverable than the A6M5c Zero-sen."

In 2 engine department, two remarkable aircraft:
P1Y1
"FE 1702 (construction number 8923) was restored to airworthiness and flown by the USAAF's Flight Test Section at Middletown from February through to July 1946. The flight revealed that the "Frances" was capable of a top speed of 340mph at an altitude of 19,400ft and was very maneuverable."
Ki-67
"Flight testing of one of the Ki-67-Is at Middletown by the USAAF revealed that the "Peggy" was faster than US medium bombers of the day, including the B-25 Mitchell and B-26 Marauder, with a top speed of 334mph. It also proved to be highly maneuverable, as IJAAF service trials pilots had discovered in 1942–43."
(All quotations are from this book: Chambers, Mark. Wings of the Rising Sun (p. 256). Bloomsbury Publishing. Kindle Edition. )

 

[Schweik]

B7A? I just love this "Japanisch Stuka".
"Three B7A2s were captured at Kisarazu, in Chiba Prefecture, by US forces following the occupation of Japan and shipped to the US. One was sent to "Pax River" for evaluation by the US Navy and the remaining two were assigned to the USAAF. Flight testing revealed that the "Grace" possessed the handling and performance qualities of a fighter, being faster and more maneuverable than the A6M5c Zero-sen."

In 2 engine department, two remarkable aircraft:
P1Y1
"FE 1702 (construction number 8923) was restored to airworthiness and flown by the USAAF's Flight Test Section at Middletown from February through to July 1946. The flight revealed that the "Frances" was capable of a top speed of 340mph at an altitude of 19,400ft and was very maneuverable."
Ki-67
"Flight testing of one of the Ki-67-Is at Middletown by the USAAF revealed that the "Peggy" was faster than US medium bombers of the day, including the B-25 Mitchell and B-26 Marauder, with a top speed of 334mph. It also proved to be highly maneuverable, as IJAAF service trials pilots had discovered in 1942–43."
(All quotations are from this book: Chambers, Mark. Wings of the Rising Sun (p. 256). Bloomsbury Publishing. Kindle Edition. )

Definitely. Three of my favorites. I didn't bring them up because somebody already discussed Ki 67 at length, and the others just didn't show up early enough or in enough numbers to play much of a role. I love the B7A it's probably (arguably) the best single engine strike aircraft design in the whole war. I have a model of it behind me as I type this, I'll take a pic and post later. Definitely would run rings around any Stuka (and then drop a bomb on it's base and come back and shoot it down). All that performance and agility plus it was heavily armed and had armor and self sealing tanks.

Problem was by the time it came out we were already into the Jet Age. And there were also some very good Allied strike aircraft coming out which didn't make it into the war in time.

 

[pbehn]

The Mosquito for me as the concept was the way of the future (unarmed fast bomber).

For various reasons the Mosquito got favourable treatment not afforded other bombers. Not only did it not use a "power egg" it had its own special Merlins. Conventional wisdom had it that a bomber should have a three man crew, the poor Hampden had four. To make the concept work he aircraft made design changes on everything that went in it, rather than the other way around.

 

[Schweik]

The Ki-49 had 8! Maybe they could have cross trained a couple of guys and fit another bomb in it... Ki-67 had "6 to 8". B-26 had 7, B-25 had 5, Pe 2 had 3.

 

[Just Schmidt]

The K-48, which looked almost exactly like a Hampden, was also quite fast, 314 mph, had armor unlike most Japanese bombers, had excellent handling, and very good range (1,500 miles). Very small bomb load of 1700 lbs / 800 kg and lightly armed, and it just seemed not to be made in very large numbers.

The Ki-49 was also fast (306 mph) and like the Ki-48, had armor and self sealing tanks (the Japanese Army seemed to figure out the need for this faster than the Navy). Power to mass (0.21) and wind loading (31 lbs) were better than most fighters. Bomb load was slightly better than the Ki-49 (2200 lbs / 1000 kg) and it was fairly heavily armed. They proved to be fairly vulnerable to P-40s though and not many were made (they were made through the war but production seemed to be at a very slow pace). I still think it was a good design with a lot of potential.

-

Unless we include the single engined bombers (here i frankly don't know about the army variants which anyway entered service before Japan's entry into ww2), the majority of Japanese bombers did have armour, the exeptions being G#M and early and not so early G4M's. You mentioned Ki-48 and 49 yourself, to this we can add Ki-21's more mature models, P1Y and Ki-
67.

According to this the reason IJAF considered the Ki 49 a heavy bomber was not its bomb load or range but it's passive and active defensive assets:

WW2 Armour and Fuel Tank Protection - What They Don't Tell You - YouTube

The part on Japanese Army starts around 26:30, the Ki-49 is a little later than that but the whole thing is in my opinion watchable.

Light, medium and heavy bombers are classifications rather than description of a role. Arguably all three kinds could be used to bomb, for an example, enemy air fields. You design (or possibly specify would be a better expression) an aircraft partly for a mission profile, partly from the technology (most importantly engines, but radar and metallurgy etc. can be mentioned also) you've got, the result can be modified and reclassified as time progresses. The resulting aircraft can end up being used in many roles that were never intended. Light-medium-heavy bombers were relative to each country and each participant in the war, even if we can to some extent agree on approximate 'universal' standards.

 

[Just Schmidt]

One more thing I wanted to add, the G4M "Betty" did not have a single flash in the pan with the sinking of the Repulse and the Prince of Wales, they continued to harass Allies air bases around Port Moresby and in the Solomons and were part of the ongoing raids against Darwin, taking good advantage of their relatively high altitude performance and excellent range to continue to plague the Allies with strike after strike. I don't think you could call them a failure. Most twin-engined bombers in WW2 proved to have fairly high attrition rates, this includes the ones we think of as good like the Ju 88 or the B-25.

I don't want to belittle the G4M, but least we forget:

pictures don't lie, and this is clearly not a G4M. It is not a certainty that the same total number, all being G3M's, could not have done that job.

The G4M had a strong structure and good survivability in the cases where it didn't catch fire. Also, though unquestioningly suffering a disaster on 20th of February 1942, the armament was good enough to shoot down two Wildcats, though far from good enough to allow them to bomb targets protected by fighters while unescorted, according to:

Avenging Pearl Harbor - The Forgotten Turkey Shoot of WW2 - YouTube

A point i don't think is made in the video is that one drawback as torpedo bomber was that it was quite large for a two engine aircraft. Single engine torpedo bombers would present far smaller targets on the torpedo run, even if they had other disadvantages

 

[Shortround6]

Mosquito is by far the best bomber.

Two Squadrons using them as bombers in 1942. No 105 started to equip in Dec of 1941, first operation was end of May 1942.No 139 squadron was equipped with Mosquitos in Sept of 1942. Debatable about early war bomber. 1939-1942 bomber.

Runners up early war (1939-1942)
For the early war, I like the A-20C, the Kawasaki Ki-48, the Nakajima Ki-49, the Martin 167 and 187, the Ju 88, the LeO 451, and the Pe-2

We can get into a debate about light vs medium.
The A-20 was usually called a light bomber max load 2000lbs inside.
The Ki-48 was light bomber, 400kg inside.
The Ki-49 was a medium (or heavy)
The Martin 167 was a light bomber. Wiki says 2000lb but other sources are not quite so generous, around 1200lbs depending on size of the bombs.
The Martin 187 was more of a medium, empty weight went up about 50% over the Baltimore. Gross weight was around 6,000lbs heavier. Bombload was 2000lbs according to most sources.
JU-88 was a medium although there is quite a difference between the A-1 and the A-4
LeO 451 is a medium, it could carry quite a load but traded fuel for bombs so actual load was usually less.
PE-2 was a light bomber. We have been over the bombloads several times.
Including 15,000lb gross weight bombers and 25-30,000lb (or heavier) bombers in the same catagory seems a bit unfair/unrealistic.


On the LeO 451 from an old William Green book (subject to correction) bomb loads.
two 1102lb bombs and five 441lb bombs in the bomb bay with 220 imp gallons of fuel.
two 1102lb bombs and two 441lb bombs in the bomb bay with 398imp gallons of fuel
two 1102lb bombs in the bomb bay with 530 imp gallons fuel
one 1102lb bomb or two 441lb bombs in the bomb bay with 712 imp gallons of fuel
plus one 441lb or one 220lb bomb in each of two wing root bays.

Under performance range with 1100lb bomb load is given as 1430miles, One would assume that is with 712imp gallons. Range with 220 imp gallons is?????
Gross weight (normal) is given as 25,133lbs 712imp gal of fuel is around 5300lbs.

The larger medium bombers had more flexibility than the light bombers but much of the bomb loads and ranges in Wiki are nonsense.
The heaviest load and longest range never go together.

 

[Schweik]

Two Squadrons using them as bombers in 1942. No 105 started to equip in Dec of 1941, first operation was end of May 1942.No 139 squadron was equipped with Mosquitos in Sept of 1942. Debatable about early war bomber. 1939-1942 bomber.

Well seeing as this thread was already discussing aircraft as rare in the field as the Ki-67, the Ju 388, and the Arado 234 then I think it's Ok to include an aircraft as important as the Mosquito. Even with two squadrons, it made a mark, and was noticed, fortunately. It's importance only grew as we know very well.

We can get into a debate about light vs medium.

Don't bother, I already stipulated what I meant by the two terms, which it has also already been established, meant different things to different air forces.

The A-20 was usually called a light bomber max load 2000lbs inside.

But not by my criteria, and the A-20G could carry 4,000 lbs of bombs (half on wing pylons, which it did on some short ranged missions. The A-20 was also n the original poll, so take it up with the OP if you have such a hankering to debate arbitrary terminology

The Ki-48 was light bomber, 400kg inside.
The Ki-49 was a medium (or heavy)
The Martin 167 was a light bomber. Wiki says 2000lb but other sources are not quite so generous, around 1200lbs depending on size of the bombs.
The Martin 187 was more of a medium, empty weight went up about 50% over the Baltimore. Gross weight was around 6,000lbs heavier. Bombload was 2000lbs according to most sources.
JU-88 was a medium although there is quite a difference between the A-1 and the A-4
LeO 451 is a medium, it could carry quite a load but traded fuel for bombs so actual load was usually less.
PE-2 was a light bomber. We have been over the bombloads several times.
Including 15,000lb gross weight bombers and 25-30,000lb (or heavier) bombers in the same catagory seems a bit unfair/unrealistic.

I stipulated what "light" and "medium" bomber meant vis a vis my post. For the Martin 167 or 187 (*by the way, the 187 IS the Baltimore, so it's not going to have any weight advantage over itself), the Pe-2 and the Ju 88, it all depended on the mission. They could carry more bombs (in some cases externally) for shorter range strikes, and less for longer range. Obviously those aircraft which remained in the war to the end were usually improved in their capabilities. The LeO 451 never got much past the 1940 stage.

The larger medium bombers had more flexibility than the light bombers but much of the bomb loads and ranges in Wiki are nonsense.
The heaviest load and longest range never go together.

You have made it clear in arguments on other threads that you think bomb tonnage matters more than accuracy, I think accuracy actually mattered (and still matters) much more - surviveability as well, and I pointed out two good example where a very small number of Pe-2s successfully carried out strikes of at least Operational significance and made it back to strike again (in fact it was the same unit which did both). Many much heavier raids (dropping many more tons of bombs) had far less impact on the outcome of the war.

As for Wikipedia, it is very limited but it's something easy for everyone to check and it's not necessarily distorting the differences between the aircraft. It's a convenient shorthand for the high level discussion, when you want to get down in the weeds you can break out the library. I don't rush to do that any more because I've spent hours transcribing data from far more authoritative sources before only to have people deny reality more than once.

 

[Shortround6]

Well seeing as this thread was already discussing aircraft as rare in the field as the Ki-67, the Ju 388, and the Arado 234 then I think it's Ok to include an aircraft as important as the Mosquito. Even with two squadrons, it made a mark, and was noticed, fortunately. It's importance only grew as we know very well.

Perhaps I wasn't clear in my post. The Mosquito, important as it was from 1943 on as a bomber had very little impact in 1942 so claiming it was the best medium bomber in th e1939-42 time period is debatable. The opening post makes no time distinction, that came later. The Ki-67, the Ju 388, and the Arado 234 have got nothing to do with 1939-1942 either although they do come into play for the 2nd half of the war.

My criteria for a light bomber is (somewhat arbitrarily) something that carries about the same amount of bombs as a fighter bomber to a range not much greater than a fighter bomber can fly. These are kind of useless unless they are super accurate or deadly (i.e. dive bombers or torpedo bombers) or have a good survival rate, though with a navigator they could also be useful as pathfinders. A medium bomber is a plane that can carry more than a typical fighter bomber (often about 2,000 lbs) and carry it a bit further than most fighter bombers can fly (say close to 1,000 miles nominal range). A heavy bomber is something that carries a lot of bombs a very long distance (say closer to 2,000 miles) - to me there's only a few of those: B-29, Lancaster, B-17, B-24, Hallifax etc.

Your criteria is somewhat arbitrary and also needs the use of the retrospectroscope. Plenty of air forces had light bombers in the 1930s and into the first years of WW II. They carried, at the time, a lot more bombs than a fighter bomber because fighter bombers either didn't exist or carried truly small payloads. Comparing 1942-44 fighter bombers to 1938-1941 light bombers skews things somewhat.
Same with medium bombers. in 1938-41/42 they carried a lot more bombs than the fighter bombers of the time (again non extant or only in small numbers with small bombs) and carried it an awful lot further, not bit further. There were very few fighters that could fly even 600 miles without any bombs in 1938-41. 1942 saw a few show up.

Heavy bombers, a bit more of the same, applying 1942-45 standards to 1939-42 skews things.

My criteria for what makes a good bomber is different from most. Most people seem to believe whichever bomber could carry the heaviest load of TNT to the target area and drop it somewhere in the vicinity was the best. To me what makes a good bomber is destroying their target at a fairly high rate, i.e. not 1 or 2% of the time but 30 or 40% of the time (per raid, lets say). And mostly returning to base intact, as in, the majority of the squadron makes it back.

Carrying the heaviest load of TNT to the target (and returning) is a good starting point for evaluating bombers. It is not the total evaluation.
However if you need 100 bombers of one type to get the target effect of 50 of another type then things do need to be looked at. the 50 larger, more expensive bombers may be a better deal than 100 cheap, small bombers.

A lot is made of bomber A having destroyed a certain target on a one day mission to prove how good the airplane was. Rather overlooks the crew. Some crews accomplished quite a bit with some mediocre (if not down right poor) aircraft.

The Russians actually got this contraption to work a few times.

from Wiki,
. On 1 August 1941, a pair of TB-3s in Zveno-SPB configuration, each with two Polikarpov I-16 fighters carrying a pair of 250 kilograms (550 lb) bombs, destroyed an oil depot with no losses in the port of Constanța, Romania.[11] On 11 and 13 August 1941, Zveno-SPB successfully damaged the King Carol I Bridge over the Danube in Romania."
However the training and rarity of the crews that could successfully use this combination kept it from becoming more common.

Aircrew training, equipement and doctrine have a lot to do with the success or failure of number of different types of bombers.
British had poor training, not very good bomb sights, poor navigation, poor bombs and not very good doctrine at the beginning of the war. Expecting much more than the air crew to die bravely was not realistic. does that mean the aircraft themselves (and their engines) were at fault?

BTW the standard British 500lb bomb at the beginning of the war held about 65kg of TNT so try to compare that to the Soviet 250KG bombs for bridge busting.

A large bomb load gives options. A small load restricts options. Options include trading bomb load for range and options in types and sizes of bombs for different targets.

Some bombers had rather tight bomb bays and despite carrying a decent weight options were restricted, but in general bomb load is a good indicator of flexibility.

British did some bombing raids that promised little hope of success, like the first operational use of the Manchester. Night of Feb 24/25 1941 they attacked the Hipper in Brest with light loads of 500lb SAP bombs (as used on the Skua). Trouble is the 500lb SAP bomb had little hope of penetrating the armoured deck/s of the Hipper.
The Manchester was pretty much a disaster as a bomber for a number of reasons but the failure of this raid had little to do with the Manchester itself.

BTW the Japanese build hundreds of these things.

because the fighter bomber of the time was this.

max bomb load 100kg. (four 25kg bombs) range 390 miles without drop tanks or bombs.

 

[mstennes]

The object of ANY bomber was to put bombs on target ( or at least in the target area) will suffering acceptable losses. The more bombs (or tonnage) per loss the better and obviously more range per ton of bombs/loss is better.

Losses could/would be from all causes. B-26 almost got canceled before it really saw action due to training losses. Better training helped, but difficult to fly aircraft, even of high performance may not be the best answer.

Mosquitoes had high performance and low losses, they could provide precision strikes but tonnage carried was on the low side. Perhaps the precision made up for it. when using 4000lb HC bombs which upped the tonnage the precision fell off.

Other planes had different trade offs, good at one thing, not so good at others.

The "Best" is probably an all around airplane that does't really stand out in any one area. Planes that are exceptional in one area tend to be lacking in others.
Like the Ar 234, fast and very survivable in the battle zone but bombing from 20,000ft and 400mph requires a might good bomb sight, especially for a single man aircraft. 1100lbs of bombs over a range of 970miles isn't so good either, A Blenheim could do better in 1939 although it had trouble with the surviving with acceptable losses part.

The B-26 ended up having a great career and safety record after Martin made some changes and pilot training was increased. That was the plane that started my dads army air corps career.

 

[Schweik]

Perhaps I wasn't clear in my post. The Mosquito, important as it was from 1943 on as a bomber had very little impact in 1942 so claiming it was the best medium bomber in th e1939-42 time period is debatable. The opening post makes no time distinction, that came later. The Ki-67, the Ju 388, and the Arado 234 have got nothing to do with 1939-1942 either although they do come into play for the 2nd half of the war.

Allow me to explain all this to you. Mosquito in 1942 was already as important as the Ju 388 or AR 234 were in the late war. Probably the Ki-67 too. You are trying to say that the Mosquito doesn't count because there were relatively few operational in the early war. There were relatively few of a lot of good types. There weren't that many Pe 2s yet either for example.

Your criteria is somewhat arbitrary and also needs the use of the retrospectroscope. Plenty of air forces had light bombers in the 1930s and into the first years of WW II. They carried, at the time, a lot more bombs than a fighter bomber because fighter bombers either didn't exist or carried truly small payloads. Comparing 1942-44 fighter bombers to 1938-1941 light bombers skews things somewhat.

So what? We all have different criteria for what we think matters or made a bomber (or any other kind of aircraft) 'good', or 'best', which are both subjective terms. That is why I explained what my criteria were in advance, so we could separate arguing about criteria from arguing about the aircraft, otherwise it becomes a hopeless mess (though some people, not saying you necessarily, like to make such a mess so as to hide bad arguments in them)

Most of the fighters as well as the bombers fighting in 1942 were 1930's or very early 1940's designs, made when they couldn't anticipate the full realities of war. They didn't know how many bombs Hurricanes and Kittyhawks could carry in particular. Nevertheless, that was the competition. I'm not saying that designers in the 1930s should have anticipated every nuance of how the war actually turned out in 1941-45, they didn't even know there would actually be a war or who would be fighting on what sides so how could they.

But in 1942, these were the designs which were competing with each other. In the Western Desert, they rather quickly figured out that Lysanders and Blenheims were not going to cut it as bombers. They were able to adapt some of their existing, not quite perfect fighters to be quite passable fighter bombers, and those were indeed in competition with Blenheims, Marylands, Baltimores and Bostons. The latter three types, though they did not carry much heavier bombs loads than a Kittyhawk necessarily, proved 'competitive' because they were adapted successfully to their missions. They had things that fighter bombers didn't have- navigators, sometimes bombardiers, more fuel, two engines.

Same with medium bombers. in 1938-41/42 they carried a lot more bombs than the fighter bombers of the time (again non extant or only in small numbers with small bombs) and carried it an awful lot further, not bit further. There were very few fighters that could fly even 600 miles without any bombs in 1938-41. 1942 saw a few show up.

Heavy bombers, a bit more of the same, applying 1942-45 standards to 1939-42 skews things.

I just divided it into early and late war, it's really not that much of a skew. In fact if you don't do that, you are comparing Pe-2s and He 111s to Ar 234s, which doesn't make much sense does it.

Carrying the heaviest load of TNT to the target (and returning) is a good starting point for evaluating bombers. It is not the total evaluation.
However if you need 100 bombers of one type to get the target effect of 50 of another type then things do need to be looked at. the 50 larger, more expensive bombers may be a better deal than 100 cheap, small bombers.

Let me help your analogy along a bit and clarify it. If you try to make it a starting point, then what you are actually doing is creating a filter or a funnel. You are placing bomb tonnage carried as a higher criteria than accuracy or survivability or range or servicability. All of which are actually equally important. If bomber A carries 5,000 lbs of bombs, but only survives one mission, and bomber B carries 2,000 lbs of bombs, but survives 10 missions, which one is delivering more ordinance? But it may actually be bomber C (carrying 1,000 lbs) which is the only one potentially accurate enough to actually hit the target. Or bomber D which isn't as good as any of the others but turns out to be the only one that can keep flying from the tropical island, desert wasteland, arctic tundra or whatever the extreme environment may be.

A lot is made of bomber A having destroyed a certain target on a one day mission to prove how good the airplane was. Rather overlooks the crew. Some crews accomplished quite a bit with some mediocre (if not down right poor) aircraft.

That is a point I would agree with, but the machine does define the limits. The Finns adapted many mediocre fighters into good fighting machines, but even they couldn't do anything with a Caudron, and they did a lot better with Bf 109Gs when they got those than they had with the older types. Training and pilot skill is always a major factor, look at the Wildcat vs. the Zero (on both sides). Or the difference in bombing accuracy and air to air combat for Navy flown SBDs vs Marine or Army flown. But we can usually see a range of success and failure in the operational history, if the planes could be adapted (and they were used long enough) we can usually see if they had potential or not.

Adaptability was actually one of the most important factors for success for any war machine, especially aircraft.

The Russians actually got this contraption to work a few times.
View attachment 613326

from Wiki,
. On 1 August 1941, a pair of TB-3s in Zveno-SPB configuration, each with two Polikarpov I-16 fighters carrying a pair of 250 kilograms (550 lb) bombs, destroyed an oil depot with no losses in the port of Constanța, Romania.[11] On 11 and 13 August 1941, Zveno-SPB successfully damaged the King Carol I Bridge over the Danube in Romania."
However the training and rarity of the crews that could successfully use this combination kept it from becoming more common.

Yes, these were used in the same incident as those 6 x Pe 2s, the difference is that these TB-3 / I-16 contraptions were ultimately lost, whereas the Pe 2s had a much higher survival rate, longer range, and better accuracy. That's why Pe-2s were still in heavy use in 1944 whereas the TB-3 was a distant memory.

A large bomb load gives options. A small load restricts options. Options include trading bomb load for range and options in types and sizes of bombs for different targets.

Poor accuracy and a miserable survival ratio in combat restrict options. Poor range restricts options. Poor serviceability restricts options. The Hampden bomber carried a heavier bomb load than the A-20 or Pe-2, but does anyone think it was a better bomber? The Whitely carried more than the A-20 and the Hampden combined, but what kind of dent did it put into the Axis cause compared to say, the Mosquito, in spite of the latter's comparatively tiny bomb load (and I mean before they started putting 4,000 lb 'cookies' on it).

Some bombers had rather tight bomb bays and despite carrying a decent weight options were restricted, but in general bomb load is a good indicator of flexibility.

Look how much havoc was wrought by the D3A, the SBD, the Stuka, the or the A-20. I don't think we can say they had a marginal impact. I guarantee D3As could have sunk the Hipper, if Skuas could lay a bomb on it. SBDs as well.

 

[TheMadPenguin]

You guys are gonna run me outta popcorn! Keep it up, I love hearing people think!

 

[Koopernic]

The B-26 ended up having a great career and safety record after Martin made some changes and pilot training was increased. That was the plane that started my dads army air corps carrier.

I've heard it argued that the wing area increase did nothing but reduce the speed of the aircraft and increase its losses. The issue was always training and a few technical issues such as the batteries that controlled the propeller pitch failing on take-off due to ground crews draining them during maintenance procedures.

 

[Schweik]

In the MTO, they did alright because they had escorts (325th FG was assigned to protect them) and could fly their missions at a fairly high cruise speed so they were in and out of the target area pretty fast.

 

[Admiral Beez]

The Ju-88 needs some kudos. First flying in 1936 and staying competitive right up to the last days of the war.