Dateline 1941: Did the Martin Baltimore have any advantages over the Douglas A-20 Havoc sufficient to justify US adoption?

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and Ablacores, but these seem to only be used in Maritime operations.

Yup, although the FAA Ablacores did carry out attacks against land targets, in particular a daring raid by nine of these aircraft on the evening of 9 July 1942 against a convoy near Tobruk, some 250 miles behind enemy lines the Ablacores were secretly refuelled by Bristol Bombays before heading off to attack the convoy, which proved successful. Ablacores were also involved in support of Torch, four FAA squadrons providing anti-submarine patrols.
 
It's really unfair to throw the B-25 / B-26/B-34 into the comparison to the A-20 as they were MEDIUM bombers (hence the "B" designation). The A-20 Havoc, A-22 Maryland & A-30 Baltimore were ATTACK bombers (hence the "A" designation). The ATTACK aircraft were characterized by having only a pilot and a rear facing gunner and depending on the configuration sometimes a bombardier in the nose . MEDIUM bombers had a full crew: pilot, co-pilot, turret gunners, bombardier, radio/navigator, tail gunner and of course greater range. Single engine ATTACK aircraft were too characterized by only a pilot and a rear facing gunner e.g. A-24 Banshee, A-25 Shrike, A-31/A-35 Vengeance.
 
And yet, they were used in almost exactly the same role, both in the Pacific and in the Med / Italy. I think it's more of a matter of degree, than of a sharp distinction. There was a great deal of overlap between these categories.

Both Baltimore and A-20 had turret defense by the time B-25s and B-26s were deployed in any numbers. Later model Baltimores had a crew of 4.

The distinction is further blurred by the A-26, which had the smaller crew and slim lines of the 'light' bombers, but did have defensive turrets, carried a larger bomb load and had a longer range than either B-25 or B-26. Like the A-20 and B-25, it had both 'hard nose' strafer versions and 'glass nose' versions with bombardiers. Most important, it was faster than all previous US light or medium bombers, with the possible exception of the A-36 Mustang. So which category does it really fit into? It replaced both A-20 and B-26 in Europe.

The 'medium' bombers were a little bit larger, a little slower, had larger crews (potentially much larger), and carried a bit heavier bomb load, but they were being used side by side, against the same enemies and the same kinds of targets, during the same period. The US preferred the medium bombers in theory, but it does seem there was a viable niche for the 'light' two-engined bombers. I'm not sure you could say one type did better than the other, or that the USAAF distinction really had that much meaning when it comes down to it. Ultimately, I'd say that 'a little faster' worked out to be more of an advantage than 'more guns', at least to a point. That seems to be the place that both British and American war-planners ended up anyway, until the jets took over.
 
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Yeah, like I mentioned (I actually wasn't sure if the B-26 had a 'hard nose' version but I know they had gun blisters on the side of the cockpit). It's also worth noting that they kind of found a sweet spot in terms of defensive armament, at least for the US bombers. Early Allied 'light' bombers had either one or two pintle-mounted defensive guns or one-gun turrets, whereas by the time they were in combat I think US mediums all had power turret defense. The later model light bombers had power turrets with HMG, and the best US version, the A-26, had two (ventral and dorsal) slim, remote-control power turrets with two HMG - both turrets manned by a single gunner.

The British had the Beaufighter, which often didn't have a defensive gun (but was fast and maneuverable enough to put up a fight with their fixed guns) and then the the ultimate WW2 'light' bomber, the Mosquito, which was another ~50 mph faster than the A-26, so that was enough speed that they didn't need defensive guns. Their earlier light - medium bombers like Blenheim, Wellington and Beaufort were gradually relegated to maritime operations or phased out.

The Germans had pintle mounted guns on what was arguably their best twin-engined bomber, the Ju 88, but their later model attack / strike aircraft had slim remote control turrets like on the A-26.

There was a tradeoff between speed and defense. If you had a bomber which was as fast as the fighters (i.e. Mosquito) then no guns were necessary. Anything slower than that and some guns were a good idea, apparently, but they had to be implemented with as little extra drag and weight as possible.

I wonder if the turret armed Baltimore was any slower? I think the A-20G was actually faster than some of the earlier marks, thanks to bigger engines.
 
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I think the A-20G was actually faster than some of the earlier marks, thanks to bigger engines.

A-20G was slower than earlier marks due to the installation of the 2-gun turret and wider segment of fuselage to accommodate that turret. Engine was still the 1600 HP version of the R-2600, the -23, in most of the Gs.
A-20Hs and Ks with 1700 HP -29 engines were still not faster than those Gs with -23s, at least when looking at British data sheets.
 
Yeah looks like you were right, though it depends what you mean by earlier marks. I assumed the faster variant was pre-war type without all the armor, self-sealing tanks, ammunition and guns, but it looks like it was the second, DB 7A variant that was the real speed demon. There was a substantial redesign from the prototype to the 7A, the 7B / A-20A, (with the one used by the French having a longer nose) and the DB-73 ordered by the French but used by the British. The development cycle is a bit confusing. Forgive me if I take a deep dive here. Joe Baugher's website helped me a lot sorting through this.

The initial French (DB-7 / Havoc I) model actually used in the Battle of France had 1,000 or 1,100 hp R-1830s. Joe Baugher says these made 305 mph at 9650 feet.

DB-7A 'Havoc II' also made for the French, but used by the British, were the first to get the R-2600-3, but I think they were lacking somewhat in armor, guns, bomb load (1764 lb max) and fuel tank protection. Wiki says these were the ones that made 344 mph. Joe Baugher says the same thing. No wonder the British liked them so much.

DB-7B / Boston III and DB-73 (made by Boeing), Boston III probably being the main type for the British during the heaviest fighting in the Med, had a longer nose, more armor + self sealing tanks, increased fuel capacity from 205 gallons to 394 gallons, and were therefore heavier, and were using 1,600 hp R-2600-11. Joe Baugher says these made 338 mph at 12,500 ft.

A-20A seems to be very similar to the DB 7B. Joe Baugher says these were making 347 mph. I'm not sure why this was a bit faster than a DB-7B / Boston III

A-20B was somewhat confusingly roughly equivalent to the DB-7A (with 'light armor' and no self sealing tanks) and a stepped nose. Most went to the Soviets. Joe Baugher says these made 350 mph. This seems to be the fastest variant.

A-20C used by the Americans in the Med and Pacific contemporaneously with the Boston III (designated by the British as Boston IIIA) had the RF-2600 engines, self sealing tanks. And also apparently individual exhaust stacks which increased speed by 15 mph! (according to Joe Baugher). Baugher says these made 342 mph.

The A-20G which was probably the main US type, had the 1,600 hp R-2600-23. Heavier armor made of thicker steel added 400 lbs, fuel increased from 540 gal to 725 gallons, and provision was made for external fuel tanks and bombs under the wings. Early models had twin pintle mounted .50 cal for the dorsal protection. From A-20G-20-DO they added the power turret, which required widening the fuselage 6". This one is listed at 325 mph by Wiki, Joe Baugher says 339 mph.. Maybe it depends on whether it's the pre- or post- turret version. About half of the A-20Gs went to the Soviets who modified them quite a bit (including putting in their own turrets) which no doubt also effected the speed, and a few dozen went to the RAAF.

The A-20H (basically a later model G) had the 1,700 hp R-2600-29. Joe Baugher says these did 333 mph

A-20J (transparent nosed variant of the G used as a pathfinder) went back to 1,600 hp and made only 317 mph, per Baugher.

So broadly speaking, there seems to have been four basic generations of this bomber: The pre-war design with the 1,000 hp engines used by the French (with success) in the BoF, about 300 mph, the 'lightweight' (and short ranged) A-20s with the 1600 hp engines (DB-7A, A-20A, and A-20B) which made ~350 mph, a better protected, longer ranged middle type (DB-7B / Boston III / A-20C) which made about 340 mph (which was arguably the most widely used type), and the later war 'heavy' (and much longer ranged) version (A-20G and H) which made around 335 mph.

In other words, A-20G did slow down but apparently not by much, at least according to Baughers numbers (it's 3 mph slower than the A-20C, and actually 1 mph faster than the DB-7B / Boston III, though 11 mph slower than the fastest version - the A-20B) although there may be a bigger difference between the turreted version and the pre-turret version. Subsequent A-20s do seem slower.

All in all though I'd say A-20 was faster than I realized and looks overall better than a Baltimore in this respect, without a doubt. Also interesting to think that these were replacing Blenheims. I imagine crews were happy with the 75 mph speed increase!
 
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Gets back to the original question.

"Did the Martin Baltimore have any advantages over the Douglas A-20 Havoc sufficient to justify US adoption?"

And the answer would seem to be no.
It's bomb load is not very different.
For the first 150 or so planes it's defensive armament is any better, after that you may be comparing two .303s in a power turret to two .303s/.30s on a free swinging mount for top defense, everything else is about equal. Baltimore then went to 4 .303 guns and then to two .50s.
The Baltimore is slower.
The Baltimore may have longer range, at least until later A-20s show up with the really big tanks inside the bomb bay (that took a while).


And As I have said before you do have to look at the B-25 and perhaps the B-26 as the USAAC was not ordering the A-20 in a vacuum. Both the B-25 and B-26 were being ordered in large numbers before the Baltimore flew so the Baltimore was only going to fit into a very narrow slot between the A-20 and the two mediums. Did the US really want to operated a 4th light/medium twin engine bomber?
 
Well obviously we know that the Baltimore wasn't adopted, so their decision was they didn't want a 4th aircraft in that category. I'm not sure I actually think Baltimore compares favorably to the A-20, I think it actually stands up a little better to B-25 and B-26, but the niche it was in was most likely better owned by the Boston.

If I was going to pick one for the US to adopt it would probably be the Mosquito, or a Pe-2 with US engines. I'm not sure how well either would have held up in the Pacific Theater though and that is where IMO they could have used a few more fast bombers.

Could they have used some of the Martin 187s they were making anyway for the British? I'd say yeah, probably. If Baltimores can survive Libya, Tunisia and Italy against Bf 109F and G and MC 202 and 205, not to mention German flak, I think it would have been effective in combat in the Pacific during the same period.

But I'm not sure I could make the argument that it was better than the A-20. I would say that the US was fairly hesitant or lukewarm in it's adoption of the A-20 compared to some other types. They eventually made 7000 of them but half of those went to the Soviets and quite a few of what was left to the Commonwealth. The few that made it to the Pacific made a good account of themselves, as did the ones in the MTO. That said, the Baltimores and Marylands (and Bostons) sent to the British & Commonwealth forces did good work against the enemy, so I'm not sure it matters.

I suspect the reason they did not adopt the Baltimore was the difficult takeoff characteristics. That would mean a higher rate of losses and aircrews. They had enough of those kinds of problems as it was (and it may be the reason why the Marauder was more or less absent in the Pacific as well).
 
It took a while for the range of the A-20 to get to where the US wanted it.
The US never ordered any of the R-1830 powered planes and went for the R-2600 powered version from the start.
Ignoring the Fuel capacities of the French and early British aircraft the Americans started with 500 US gallons in the A-20 and A-20A designs.
However when protection was applied the US versions dropped to 400 gallons until the A-20C which got a 140 gallon tank in the upper bomb bay. No reduction in the bomb load.
The A-20G-20 could carry up to 325 gallons in the upper bomb bay in three tanks. These tanks were self sealing.
The G's also had a couple of ferry tank arrangements with non-self sealing tanks but that was well after any decision about the Baltimore would have been made.

The A-20 had a bit of a restrictive bomb bay. It could carry four 500lb bombs inside, but the racks limited it to just four bombs even if they were smaller, only four 250lb bombs for example. Some the Gs got external racks but again that is after any decision about the Baltimore would have been made.

The B-25, while slower than the Baltimore (although not by much) could carry 3000lbs inside without much trouble and could accommodate a wide variety of bombs and a wide combination of bombs. The Baltimore bomb bay also seems to be limited and the bomb racks were attached to the front and rear wing spars. It appears the plane could hold two 500lb bombs on each spar or three 250lb bombs or two 250lbs or a combination?

There are some illustrations here on this website.

As far as the Pe-2 goes, why bother.
Unless you really change the fit/finish and get a really good engine it is slower than the A-20. doesn't carry as much for bombs, is shorter ranged and doesn't have any better defensive armament.
The 360mph speed listed in Wiki is very wishful thinking.
 
Their earlier light - medium bombers like Blenheim, Wellington and Beaufort were gradually relegated to maritime operations or phased out.

Agree with you on the designations and difference between attack bombers and medium bombers, usage became blurred. The Blenheim became classified as a light bomber and saw replacement with Mosquitoes and Bostons, Mitchells, Baltimores etc, but the Beaufort was the opposite; it was designed for the maritime role - it was a torpedo bomber that was often used as a strike aircraft carrying bombs, the Aussies certainly used it in that role.


The Mosquito is interesting as it was used both in the level bombing and attack role, two different variants doing the different duties, but the same airframe, the FB.VI variant armed with four x .303s and 4 x 20mm cannon in the attack role, even though B.IVs, the unarmed bomber variants did carry out interdiction roles at low level...
 

This is one area where the Maryland clearly surpassed the Boston, and to some extent, so did the Baltimore, because they both seem to have had a fairly good range right out of the gate.

Baugher gives these ranges for the various Boston types:

DB-7 - Range with a 2,000 lb load 462 miles
DB-7A - 490 miles
DB-7B / Boston III - Range with 2,000 lbs load 525 miles, with 1,000 load 745 miles
A-20C with 1,000 lb load 745 miles
A-20G with 2,000 lb load 1025 miles (delivered Feb 43)

Until this discussion I didn't realize how little fuel the early Bostons carried, even the A-20C was only carrying 520 gallons.

Maryland Mark 1 was supposed to have a 1,300 mile range in 1941 without any kind of extra tank, Baltimore 980. I think all these are one - way ranges so actual combat radius is much less of course.

One other interesting thing I noticed, is the Maryland Mk II, the main variant used in the Med by RAF and SAAF units, actually had a slightly more powerful engine (R-1830-S3C4-G) rated for 1,000 hp at altitude, vs. 900 for the earlier Mk 1. So presumably they were a bit faster. All the stats I can find are for the Mk I (even where they say Mk II, it's the same stat block)


Pe-2 because it's a dive bomber. We have debated and discussed bombers enough to know, my thing is accuracy. In the PTO, the US could have used another accurate strike aircraft that could hit ships. They eventually worked out the mast-height bombing with the A-20s and B-25s but that took a while, and their torpedoes didn't work. Army A-24s didn't work the way SBDs did because the Army pilots didn't really have dive bomber training.

In some of the crucial battles around Milne Bay, Guadalcanal etc., the Army didn't have any effective strike aircraft useful against ships, their best bet was the fighter bombers and those pilots were not trained for it, nor did those aircraft have the range really. They did sink a couple of ships but it would be an exaggeration to say they were effective in that role.

Even at ~330 mph top speed the Pe-2 would have a pretty good chance to outrun most Japanese fighters and would be better at evading flak than many other Allied types, while probably having better accuracy than any Allied bomber except a (navy piloted) SBD, or maybe later war SB2C. If you put say, some R-2600s in them, I don't think that 360 number would be out of reach.

For that matter I think some A-36s could have been very helpful in the PTO. They should have been easily fast enough to evade A6M and Ki-43.
 

Mossie seems to have done just about everything well, though the wood construction didn't seem to appreciate perpetual rain, high humidity and heat. So not ideal for the Pacific.
 
A-36s were used in the CBI to good effect, but their range would be a limiting factor if used in the PTO.
The USAAF used A-20s and B-25s against Japanese shipping and ground targets with devestating effect.
I can't see the Peshka offering anything more than the A-20 and B-25 were capable of.
 
PE-2's numbers (range and speed) are with internal bombs which are limited to six 220lb bombs. The bigger bombs ( like 550lb) are carried externally. While this adds to the flexibility it also means that both speed and range are not what the stats say when carrying the larger bombs.

Early B-25s held 652 gallons in the wings, during the B-25C & D production run aux wing tanks were added that held 300 gallons. Then you had various tanks that fit into bomb bay or into the waist of the plane behind the bomb bay.
The Baltimore falls in between the A-20 and the B-25 and was a tail dragger. No US large bomber after the B-23 used a tail wheel except the Ventura and since that was a modified version of the Super Electra/ Hudson/Loadstar it inherited the tail gear.

Douglas also started work on the A-26 in late 1940 which might have also influenced the US lack of Interest in the Baltimore.
 
Mossie seems to have done just about everything well, though the wood construction didn't seem to appreciate perpetual rain, high humidity and heat. So not ideal for the Pacific.
Yes the Mosquito couldn't be used anywhere it rained. Luckily Britain is well known for for its dry low humidity climate.

Mossies were used for years in India, Hong Kong and Burma without any problems.
 
A-20s, until the solid nose versions had 3 man crews. Sometimes a 4th man was carried to act as gunner on the lower rear gun. Sometimes this position was listed (and a seat provided) but the crewman not carried.
Maryland had a 3 man crew.
Baltimore had a 4 man crew.

Some sources are a bit misleading, Wiki lists the following for the Maryland.

"Crew: three (pilot, navigator/bomb aimer/gunner, and radio operator/gunner)"

But there was no flexible gun in the nose/forward fuselage of the Maryland leaving the navigator/bomb aimer nothing to "gun" with.

B-25s and B-26s started with 5 man crews. 1 or 2 very agile gunners who were expected to move around the plane and man different guns in various positions. And/or either co-pilot or radio man was expected to get through or over the bomb bay to help man the rear guns.
Weight charts of the early planes were rather optimistic in this regard.
 

It was a while before the A-20s and B-25s were doing the masthead and skip-bombing which made them effective against Japanese shipping. Basically it began with General George Kenney. The first use was in Oct 1942 in Rabaul, and the first widespread use of it was during the Battle of the Bismark Sea in March 1943. The Battle of Coral Sea was in May of 42, Milne Bay was in August - September 1942.

They actually did some successful skip-bombing attacks with B-17, I think in Rabaul. Apparently the Soviets used P-40s and Sturmoviks to do skip-bombing, so maybe they could have done it with fighter-bombers. However skip bombing and mast-head bombing while effective against transports and smaller vessels was pretty risky to use against major warships. I think some A-36 (or going more far out, Pe-2s) would have been helpful to have on-hand.

The Allies were a bit short on effective land based anti-shipping aircraft, especially in that pivotal first year of 1942. General Kenney improved matters a great deal making good use of both US and British aircraft that were available - Various fighters, A-20s, B-25s, B-26s, B-17s, Hudsons and the Aussie Beaufighters and Beauforts.
 
Yes the Mosquito couldn't be used anywhere it rained. Luckily Britain is well known for for its dry low humidity climate.

Mossies were used for years in India, Hong Kong and Burma without any problems.

Excellent use of sarcasm! But I think you are misguided sir. I gather the issue with the Mossie was that the glue in the wood delaminated under hot and humid / wet conditions. Combination of the two, in other words. England does have the wet part.

My understanding is that they did actually have a lot of problems with Mosquitoes in the China-Burma-India zone and eventually withdrew or replaced them.


"The first squadron to fully convert to the Mosquito was No. 45 Squadron. It began to receive the FB Mk VI in February 1944, but it would not fly its first Mosquito missions until October 1944. The aircraft suffered from a series of unexpected crashes during 1944, which were officially blamed on problems with the glue used to bind the wood together, caused by the heat and humidity of India. The situation became so bad that in November 1944 all Mosquito operations over Burma were cancelled while the aircraft were checked for air worthiness."
 

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