# B25 or B26, which was the better bomber?



## pattle (Sep 23, 2013)

Sorry if this thread has already been done, I did look back but surprisingly I couldn't see anything.
The B25 and B26 were aircraft of a similar nature both being armed twin engine bombers designed and used for broadly the same purpose. The attributes of these two planes did vary somewhat with the B26 being faster and able to carry a heavier bomb load than the B25 which balanced out it's comparative weaknesses with greater range and ceiling than the B26.
The RAF chose to use the B26 in the Med and the B25 in Northern Europe while the USAAF chose to do things the opposite way around by using their B26's in Northern Europe and their B25's in the Med, my understanding is that this situation mostly occurred due to there having been a need for USAAF medium bombers in North Africa at a time when only the newly arrived B25's based in England were available, from what I can gather both aircraft were successful in both theatres. 
At wars end however the B26 was fast tracked to the scrapyard while the B25 managed for some years to secure a limited future in the new USAF, consequently today while we are rather flushed with B25's while only a very small number of B26's survive. 
I wonder if the early reputation of the B26 as a dangerous aircraft coupled with the fame of the B25 through it's various exploits such as the Doolittle raid was responsible for the B26s downfall and obscurity. I think in the B25 and B26 we have a rare opportunity to compare two separate aircraft on a level playing field.

Please nobody bring Mosquitos into this.


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## Conslaw (Sep 24, 2013)

Pattle, yours was a nice, concise summary of B-25 vs. B-26. As a mental exercise, I tried to come up with my own list of the top 20 combat aircraft of World War II. I had the most problems with medium bombers. 

I can only guess the reason why the B-25 remained in service but the B-26 did not. The B-26 was like a 2-engined substitute for a heavy bomber. It's two engines were only 20% less powerful than the 4 engines on the B-24 and B-17. The B-26 could not bomb from the same altitude as the B-24 or B-17, and it didn't have the range of the heavies. 

The B-25 was somewhat less powerful than the B-26, but it was also lighter. Presumably, it was a lot less resource intensive to fly. That's extra important at the end of a long supply line. North American embraced the field experiments using the B-25 as a dedicated strafer and skip-bomber. After the war, the fact that the B-26 was slightly faster than the B-25 wasn't important. What was important was that the B-25 was readily available, had enough fuselage room to carry a useful load of people and stuff, was easy yet rewarding to fly and had low operating costs. Another factor moving the B-26 out to pasture was the arrival of the Douglas A-26 Invader. The A-26 carried the same or greater bomb load as the B-26 over the same or greater distance, but it was a good 50 MPH faster and had a smaller crew. A burst of production of A-26 models at the end of the war meant that there were enough A-26s around to man the front-line medium bomber units that remained after post-war downsizing.

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## GrauGeist (Sep 24, 2013)

The B-25 was a good close support medium bomber as well as a solid gunship platform as the B-25G/H/J. The B-26 (not A-26) while being a handful to operate, proved it's worth with pinpoint strikes and it's ability to stay out of harm's way with it's speed.
I think it would be hard to compare the two, honestly, as they both filled thier niches completely.

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## pattle (Sep 24, 2013)

Um having had time to think about this a little more the thought I had in my head last night when I wrote this thread was more along the lines of which was the better bomber in Northern Europe rather than the better bomber in general. The Marauders operated by the SAAF, RAF and Twelfth Air Force in the general Mediterranean area did great things but as I have not read of them in many years they are not fresh in my memory, perhaps I should read a little on how both these bombers were used by the Americans in this theatre . 
I recently read a very good book called Third Reich Intruders which told the story of the RAF's medium bomber attacks against occupied Europe from UK bases. The RAF and USAAF eventually pretty much settled on using their respective B25's and B26's from between 10-15000 feet on similar targets. The RAF had far fewer B25's available than the USAAF had B26's, often it was the case that the RAF would carry out medium bomber raids with up to three sorts of bomber aircraft usually Havocs, B25s and Mosquitos in different waves at different heights. These raids were on occasion timed to coincide with USAAF B26 raids and both were escorted by liberal amounts of fighters.
From what I have read the USAAF achieved great accuracy with the B26 in these medium level missions, if the USAAF had of had the B25 instead of the B26 in Northern Europe I wonder if it would have achieved the same level of success, I suspect the B26 was being used in a manner that exploited it's advantages and minimised it's weaknesses. Had the B25 been used in the B26's place in this theatre then my guess is that it's use would have also been tailored to it's best abilities and that while it's method of use may have been different there would have been little difference in results. 
Having had time to mull this over yet again, I think this thread should really of been "did the USAAF base B26's in England because they believed them to be superior to the B25?" I think there may be a common assumption that this was the case as it was true with other types of aircraft, for myself I think the situation arose through accident rather than by design.


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## GregP (Sep 24, 2013)

They built 9,984 B-25 Mitchells that flew 63,177 sorties and dropped 84,980 tons of bombs. That’s 1.3 tons per sortie. The loss rate per sortie was 0.0060, or 166 sorties per loss.

They built 5,288 B-26 Marauders that flew 129,943 sorties and dropped 169,382 tons of bombs. That’s 1.3 tons per sortie. The loss rate per sortie was 0.0070, or 143 sorties per loss. Some say the B-26 was a handful to fly. From hearing guys that flew it, it wasn't. What was unusual was that it came over the fence some 25 - 35 mph faster than other, comparable aircraft of the time. So it SEEMED harded, but all that was happening was that the airstrip was disappearing a bit quicker on rollout.

Those numbers are for the ETO and the tons are 2,000 pound tons (short tons). Offhand I’d say they were about even with the B-25 being much more versatile. It was used for recon, maritime patrol, had a ton of guns fitted for attack, and was safer around a short airstrip. But you would have to work some to prove one was significantly better than the other.

Both were good planes to be in during WWII with significantly lower loss rates per sorties than any heavy that I am aware of.

Interestingly enough, the Douglas A-26 Invader compares favorably, though with significantly less use. It only flew 11,567 sorties and dropped 18.054 tons of bombs for an average of 1.4 tons per sorties. The loss rate was 0.0058, or 173 sorties per loss. It got to the war fairly late but did well with respect to other US medium bombers ... though it was an Attack Plane by designation.

The Douglas A-20 dropped 0.5 tons per sorties and had a loss rate roght between the B-25 and B-26.

Again, these are ETO numbers.

Found the numbers here: AOL Lifestream : Login

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## Shortround6 (Sep 24, 2013)

Thank you Greg, 

As the end of the war came it may be that with more B-25s available there were more spare parts available to keep them going? 

Put that together with the B-25 being easier to fly and the speed difference between the late versions was all that great (15-20mph?) and both were too slow and it may have been a no brainer as to which one was kept for a few more years. 

Note that this has very little to do with combat capability of the aircraft.

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## GregP (Sep 24, 2013)

We have a B-25 at the Planes of Fame and it is very reliable and easy to fly. We don;t have a B-26, so I can't say from any personal experience, but the P&W R-2800 was VERY reliable. Can't say from any personal knowledge of the Marauder systems and airframe, but I suspect that the fact we had almost twice as many Mitchells after the war that were easier to fly (meaning slower in the pattern) may have something to do with it.

If you fit the gun nose and side cannons, the B-25 was a formidable ground attack plane and despite the slight difference in bomb capacity, it carried the same payload per sortie as the B-26 did in the ETO.

Shortround, which do you think had better combat capability? Maybe a short explanation as to why? I have no agenda here, just curious. We KNOW the B-26 delivered more bombs, but that may have been due more to missions assigned than to inherent capability, I can't say myself. All of the people I know with experience in either type are from the B-25 crowd, and they naturally favor the B-25.

Can anybody with B-26 experience ring in here?

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## Shortround6 (Sep 24, 2013)

We may have to search the manuals. Some performance numbers seem very close and of course, vary by model. 

Early B-25s went 20,000lb empty and 31,000lbs gross while the "J" went 21,100 empty and 35,000 gross with a 41,800lb max over load using the same engines. 

Early B-26 went 21,741 pounds empty, and 28,367 pounds gross, 33,022 pounds maximum with the later B series (big wing) going 24,000 pounds empty, 37,000 pounds combat. later versions had even more weight but I can't fins it at the moment, Engines did increase in power some what but not a lot. 

Without breaking it down by model, weight, bomb load and fuel load it is going to be tough. 
The Navy used several hundred B-26s as target tugs and kept some of them until 1955.


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## GregP (Sep 24, 2013)

Don't go looking too hard, SHortround. 

From your comment about haviung nothing to do with combat capability, I inferred you thought one was much better than the other. Incorrect assumption on my part it would appear. I was just curious.


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## tomo pauk (Sep 24, 2013)

Looking out for the speed figures for the B-26, seem it was good for 315 mph until the bigger wing was introduced. Once that was done, following shortly by wing inclination, the top speed went down to circa 280 mph. So while 1st B-26s were tough catch for Zeroes, hoping to run away from the Bf-109 or Fw-190 does look like a loosing proposal.

B-26 Mardauder by Ray Wagner - Page 1


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## davebender (Sep 24, 2013)

Heavy bombers are expected to require a long paved runway. WWII era medium bombers are expected to operate from forward area grass airfields. B-25 was considerably better in this critical performance area which isn't obvious from looking at the performance summary.

Which bomber had superior endurance (i.e. could loiter over battlefield)? Another important feature of a medium bomber.

Both level bombed using Norden sight so I assume bombing accuracy should have been similar.


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## Ivan1GFP (Sep 25, 2013)

Pardon me for rambling a bit.

Actually most B-26's didn't use the Norden bombsight. Their operations (at least in the MTO) were at low / medium level so the fancy Norden didn't help all that much. My former neighbour flew one with the 320th BG in MTO and they didn't even install oxygen in their planes. Typically at least one set of the package guns on the sides of the nose were removed and eventually on the later models, even the fixed gun firing through the nose cone on the lower right was removed. Another friend of mine flew B-25s during the war though we didn't talk much about that at the time.

The B-26 had a reputation for being a "Hot Ship" while the B-25 didn't. Performance-wise, they were a pretty even match with about a 5-10 mph advantage to the B-26 at maximum. Early B-26s were capable of about 320 mph. Later versions were capable of around 285 mph. The B-25 was a draggy ship and the B-26 wasn't. The B-26 tended to leave the target in a shallow dive after the bomb run and was typically going about 350 mph TAS at that point which made it very hard to intercept. I don't know if the more draggy B-25 could do that as well.

Although neither ship was a fighter, I have heard of more people doing fancy flying with the B-25 than trhe B-26.

Although their maximum speeds were close, the Take-Off and Landing speeds of the B-26 were consideraly higher and losing an engine on take-off was more dangerous. Loads and balance on the B-26 were very critical with occasional nose gear failures when nose heavy. I have not heard the same stories with the B-25.

The B-26 started with two bomb bays but on later versions, the Aft bomb bay was sealed and then removed. This reduced the bomb load to 4000 pounds which was actually a bit less than the 5500 or so that the B-25 could carry. I don't know what they actually flew with on a typical mission.

Armament was pretty similar in the late versions in my opinion, but the B-26 had a reputation for being able to take more damage. FWIW, according to the Warbird Tech book, an attempt was made to fit R-2800 engines to a B-25. The speed was then around 350 mph, but the aircraft crashed after a structural failure in the air.

Opinions:
All in all, I believe the B-25 was the "better" aircraft. It was more adaptable to modifications and easier to operate. I believe the design was also better and less "cutting edge". There was nothing fancy about it. Changes to it didn't drastically change it.

The B-26 was originally designed to be a VERY fast medium bomber with everything sacrificed for speed. Everything was balanced in the design for that with a tiny wing and highly supercharged engines. When the intended engines were not available, it lost some of that speed. When the "Baltimore Whore" gained bigger wings to improve its take-off and landing characteristics, it lost more of that speed. When the wing incidence was increased to improve its attitude at cruising speed and take-off, it lost even more speed though by that time it didn't matter much any more.

Strangely, the B-26 always had a symmetrical airfoil more typically seen in aerobatic aircraft. This in my opinion was a serious mistake and instead of changing the airfoil, the choice was made to increase the angle of incidence. Looking at a late model (F or G) Marauder, I have always gotten the impression the aircraft could not decide which way to go. The engines and wing pointed one way while the fuselage pointed another. That could not have been good for drag.

The B-26 was purchased off the drawing board and I believe this was also a mistake. The design had handling faults which never were cured. The Martin company also appeared more interested in just selling more aeroplanes than improving their product with one famous case involving Harry Truman.

Hope this adds something to the discussion.

- Ivan.

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## drgondog (Sep 25, 2013)

Defining which was the Better bomber depended entirely on the mission. The statistics on loss rates are probably misleading as the B-26, when moved to the 9th AF, was tasked to medium altitude precision daylight bombing. It penetrated to targets in western Germany out of range of continuous escort in late 1943. in 1944 it was accorded 9th AF fighter escort but smaller numbers so hard to know what the air to air defense impact to losses were but it is intuitive that the B-26 operated in murderous flak.

The early experiences of the A-20 (first 8th AF bombing attack 4 July 1942) and B-25 and B-26, unescorted, were All disasters so it would be hard to gauge 'toughness' or survivability on the early experiences. Loss per sortie is interesting if all the sorties for each a/c were in the same high threat environment, but historically the B-26 seemed to operate in a higher threat (don't know the metrics) than either the B-25 or A-20.

The A-26 flew the same mission profile in the 9th AF as the B-26 so it would seem to be comparative. Having said that the 1943 through Summer 1944 LW threat was far higher than when the A-26 started operations. This is also why it is tough to compare B-25 vs B-26 in ETO. 

My father flew all four at one time or another but only the A-26 in combat (Korea). During his career in peacetime he got most of his requisite monthly flight time while at Pentagon in B-25s out of Bolling AFB. It was hard to pin him down on the preference between B-25 and B-26 but he really liked the A/B-26 Invader and loved the A-20 as far as fun flying. 

Personally, the A/B-26 is by far the superior a/c, the B-25 was kept around because it was nearly the same performance as the B-26B but deemed a more forgiving airplane, cheaper to operate and used primarily as a utility aircraft and trainer. AFAIK the B-25 never served in combat for USAF after WWII as the A-26 took over all the combat missions of A-20, B-25 and B-26.

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## GregP (Sep 25, 2013)

Well said, Bill. 

There's really very little to add or disagree with in your reply.

As an interesating aside, AeroTraders, across the tarmac from the Planes of Fame, is currently restoring an A-20 an A-26, and a B-25 all at the same time. The A-20 is coming along nicely and the A-26 will have everything functional, including the very complex gunner position that alows the gunner to select either the upper or lower turret via remote control and operate it.


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## spicmart (Sep 25, 2013)

Did the Marauder feature a laminar wing profile?


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## drgondog (Sep 25, 2013)

No


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## Ivan1GFP (Sep 25, 2013)

spicmart said:


> Did the Marauder feature a laminar wing profile?



No. As I pointed out earlier, the airfoil choice was not optimal.

- Ivan.


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## OldSkeptic (Sep 26, 2013)

Wasn't the B-26 responsible for the term "one a day at Tampa Bay"? A reference to what a pig it was to fly and how many trainees (even experienced pilots) it killed, especially on take off and landing?

I mean "required an unprecedented landing speed of 120 to 135 mph" .. what a disaster, who came up with that nonsense?

Oh found it: "In 1942, Glenn Martin was called before the Senate Special Committee to Investigate the National Defense Program, or Truman Committee, which was investigating defense contracting abuses. Senator Harry Truman, the committee chairman, asked Martin why the B-26 had troubles. Martin responded that the wings were too short. Truman asked why the wings weren't changed. When Martin said the plans were too far along and besides, his company already had the contract, Truman's response was quick and to the point: In that case, the contract would be canceled. Martin said corrections to the wings would be made.[11] (By February 1943, the newest model, the B-26B-10, had an additional 6 feet (1.8 m) of wingspan, plus uprated engines, more armor and larger guns.)[12]"

Translated: they didn't give a S%$t.

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## pattle (Sep 26, 2013)

I am not sure whether some aircraft manufacturers in America were just in it for the money and didn't really care very much about the standard of their products or whether they were simply just manufacturing what was agreed between them and their government, I think there was some of both. The B25 was one of those planes where the designers had got everything pretty much right at their first attempt which you could argue left little room to later improve the B25.


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## Shortround6 (Sep 26, 2013)

Manufacturers may have been reluctant to change for a number of reasons. Without knowing the details of the contracts it is hard to judge. A lot of the later contracts were "cost plus", the actual cost to build the aircraft were figured out and the company was paid that price _plus_ certain FIXED percentage' like 3%. Some contracts allowed for fluctuation in the "cost" of the aircraft. 

Say you have a contract for 1000 airplanes and it may have a problem (high landing speed) and the Government wants you to change the plane in mid production. Who pays for the new tooling? The original contract may have specified delivery dates, first 100 planes by date xxxxx, 500th plane by YYYY and 1000th plane by ZZZZ. Some contracts had penalties for late deliveries. The were also penalties for overweight aircraft ( try to add 6ft of wing wight NO increase in weight) and performance penalties. Each plane that _failed_ to meet contract speed (-3%) was subject to a penalty for _each_ mph it failed to make speed by. 

There may be a LOT of parts of the contract that need re-negotiation to fix the landing speed problem and if the company isn't really making that much money per plane to begin with ( and maybe they were, I don't know) claiming a company is "greedy" because they balk at certain changes doesn't seem quite fair. 

As far as the later B-26s go. Douglas had flown the prototype A-26 in July 1942. The Martin B-26 was a done deal in late 1943, they could tilt the existing wing 3.5 degrees (or some other number) or design and build not only a new wing but but new jigs and fixtures to build the new wing. It would not only cost money but could very well delay production (make more of the non-tilted versions while tooling up or do without?)

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## tomo pauk (Sep 26, 2013)

Maybe install Fowler flaps, so the wing remain without inclination?



Ivan1GFP said:


> No. As I pointed out earlier, the airfoil choice was not optimal.
> 
> - Ivan.



I'd add that so was the wing size - basically, Martin (company) was counting that thick and small wing will beat the thin wing of greater area. Once proven wrong, the wing got bigger (drag went up), and was inclined after that (drag went further up). 
Choice/implementation of high-lift devices also left much to be desired, too.

BTW, according to the B-26 manual, the wing incidence went from 3 and half degrees for the B and C versions up to 7 deg at F and G versions.


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## tomo pauk (Sep 26, 2013)

duplicate


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## Shortround6 (Sep 26, 2013)

tomo pauk said:


> Maybe install Fowler flaps, so the wing remain without inclination?.



It may be hard to "install" Fowler flaps in an _existing_ wing. Location of rear spar, aerodynamic loads on spar/wing and such may affect the existing design and tooling.

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## drgondog (Sep 26, 2013)

Changing a wing is a Big Deal. Period.


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## drgondog (Sep 26, 2013)

OldSkeptic said:


> Wasn't the B-26 responsible for the term "one a day at Tampa Bay"? A reference to what a pig it was to fly and how many trainees (even experienced pilots) it killed, especially on take off and landing?
> 
> I mean "required an unprecedented landing speed of 120 to 135 mph" .. what a disaster, who came up with that nonsense?
> 
> .



It was more a matter of training. My father was with the 336th BG at McDill in fall, 1943. Had no problem with the B-26A or B, just remarked that you needed to be conscious of mandatory higher airspeed requirements taking off and landing. he liked the airplane.

When he was CO of the 355th FG he routinely acted as IP for fighter pilots wishing to qualify in the airplane. No accidents for any of them.

As to high airspeed requirements? think of landing an F-105 for comparison..

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## drgondog (Sep 26, 2013)

pattle said:


> I am not sure whether some aircraft manufacturers in America were just in it for the money and didn't really care very much about the standard of their products or whether they were simply just manufacturing what was agreed between them and their government, I think there was some of both. The B25 was one of those planes where the designers had got everything pretty much right at their first attempt which you could argue left little room to later improve the B25.



The B-25 had some wicked low speed stall issues until they fine tuned the design of nacelles and dihedral.


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## drgondog (Sep 26, 2013)

Ivan1GFP said:


> No. As I pointed out earlier, the airfoil choice was not optimal.
> 
> - Ivan.



In addition there was little known about laminar flow airfoils in 1938 when the P-38 was in design/prototype stage. NAA took a huge chance on the modified NACA/NAA 45-100 in 1939 several months after the XP-38 first flew.

I'm not sure, even in retrospect what the optimal airfoil is for a P-38. One could start with an assumption of thinner airfoil to delay onset drag rise but Lockheed wanted the higher CL for climb performance and didn't know about transonic issues when the preliminary design was in progress.


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## Balljoint (Sep 26, 2013)

drgondog said:


> I'm not sure, even in retrospect what the optimal airfoil is for a P-38. One could start with an assumption of thinner airfoil to delay onset drag rise but Lockheed wanted the higher CL for climb performance and didn't know about transonic issues when the preliminary design was in progress.



As I understand the spec, the P-38 was initially to be an interceptor with a rather ambitious RoC requirement. The thick wing was a means to meet this challenge.


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## davparlr (Sep 26, 2013)

Both of these aircraft were excellent aircraft and were available at the start of the US war and, with their crews, performed heroically throughout. Due to its simplicity and better range, I think the B-25 was the most useful. Both aircraft were obsolete as war fighters by the end of the war and were phased out of combat. The B-25, because of its simplicity and ease of flying, soldiered on basically as trainer. The excellent A-20 and much more powerful A-26 led the way to more modern battlefields.

The B-26, always one of my favorites, has, in my opinion, gotten a bum rap. Most of it initial problems were manufacturing and maintenance quality issues, not in basic design. And for the high wing loading/high landing speed issue, the AAF should have left the wing alone and fixed the pilots. The B-26 was a harbinger of the future with better performance and higher wing loading, the newer A-26 had a 13% larger empty weight wing loading than the B-26A/B, the B-29 had 12% greater empty weight wing loading, although it had Flowler flaps (they still needed to be able to make no flap landings!). Approach/landing speeds for the B-26 were probably close to the contemporary P-47 numbers. Interestingly, the Martin proposal for the B-26 reflected performance with different growth engines, max speeds went from 323 mph w/initial engine (it actually did 315 mph), up to 368 mph w/2 stage 2speed R-2800 (392 mph with a turbo R-2800). It even included a turbo R-3350 version with a top speed of 413 mph. If the AAF had trained its pilots to handle the high performance B-26, there would have been no need to expend the money on developing the XB-28, which had a higher wing loading and was only a few miles faster than the proposed B-26 with the same 2 stage 2 speed R-2800. And this very fast plane could have been available much earlier, and therefore more useful, than the XB-28, I would guess. If the aircraft was initially designed with this growth in mind, the upgrade would only require an engine change.

As a footnote, for a long time, EVERY USAF pilot was checked out for competency in the T-38, an aircraft that flew approach around 180 mph touched down at 155 mph. Understanding and handling high wing loaded, fast aircraft does not require unusual or exceptional piloting skills to safely master, but it does require education and training.

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## wuzak (Sep 26, 2013)

When Martin added extra wing area, extra weight was asked to be carried, so that the wing loading was as bad as ever.

The 2 stage R-2800 B-26 was the XB-27, the R-3350 version was the initial XB-33. That was changed to a 4 R-2600 design because of the shortage of R-3350s.


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## GregP (Sep 26, 2013)

I can tell you this about the T-38 ... whatever you do, don't let it get slow in the pattern. If you do, it can develop high sink rates that are impossible to stop before intersecting terra firma, even with afterburner. I've flown the simulator and if you get slow in the turn to final, you will not make the runway on that approach. You may make a go-around or may become a lawn dart.

Fly it by the book and you'll do fine. Try seat-of-the-pants and you won't have a good life expectancy.

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## pattle (Sep 27, 2013)

According to the 39 Squadron B26 Marauder Associations website 521 Marauders were supplied to the RAF, total losses were 154 out of which 55 were to enemy action and 99 to accidents etc. Out of the 521 Marauders supplied to the RAF the majority were passed over to the SAAF with the RAF operating only three squadrons itself, the early Marauders operated by the RAF were also the only ones to be used as torpedo bombers.


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## davparlr (Sep 27, 2013)

GregP said:


> I can tell you this about the T-38 ... whatever you do, don't let it get slow in the pattern. If you do, it can develop high sink rates taht are impossible to stop before intersecting terra firma. I've flown the simulator and if you get slow in the turn to final, you will not make the runway on that approach. You mey make a go-around or may become a lawn dart.
> 
> Moral of the story is simple, fly it by the book and you'll do fine.



You are correct. As with all high wing loading aircraft, airspeed is CRITICAL. They load up with drag real fast. With the T-38 you had in your left hand a couple of toy GE engines with afterburners that were always eager to give you an assist. What a great airplane! I look back to my T-38 days with great fondness, forgetting the pain of being in a training situation!



pattle said:


> the early Marauders operated by the RAF were also the only ones to be used as torpedo bombers.



The USAAF used four torpedo armed B-26s flying from Midway to attack the Japanese invasion force. It is an impressive story I have already posted but will repeat. Of the four unescorted B-26s, three made it to torpedo range with no success, not surprising due to lack of training and the torpedoes they were using. One B-26 flew down the deck of the Akagi machine gunning all the way. Another one just missed a kamikaze type of attack missing Adm. Nagumo by only a few feet. Two of the four B-26s made it back but were well shot up. According to "Shattered Sword", the Japanese were impressed by the B-26s saying they were "blazing fast" and "difficult to bring down".

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## spicmart (Sep 27, 2013)

Ivan1GFP said:


> No. As I pointed out earlier, the airfoil choice was not optimal.
> 
> - Ivan.



At least it looks like it with the wing leading edge being sharper than those of most other planes, it just looks sleeker.
So did the Mosquito's wings. That's why I ask.


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## pattle (Sep 27, 2013)

The USAAF used four torpedo armed B-26s flying from Midway to attack the Japanese invasion force. It is an impressive story I have already posted but will repeat. Of the four unescorted B-26s, three made it to torpedo range with no success, not surprising due to lack of training and the torpedoes they were using. One B-26 flew down the deck of the Akagi machine gunning all the way. Another one just missed a kamikaze type of attack missing Adm. Nagumo by only a few feet. Two of the four B-26s made it back but were well shot up. According to "Shattered Sword", the Japanese were impressed by the B-26s saying they were "blazing fast" and "difficult to bring down".[/QUOTE]

Yes you are right, I forgot about that sorry. I don't know if this was the only time they were used in this way by the Americans though, it was a very brave thing that the Marauder crews did on that day but it was almost suicidal and makes me think of the Swordfish attack during the channel dash.


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## Lipppy (Jan 15, 2016)

When comparing the B 25 to the B 26, it is useful to look at the production numbers of each. We made almost twice as many of the Mitchells and we did the Marauders.


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## glennasher (Jan 17, 2016)

I knew a fellow (long ago) who flew on B-25s during the Pacific War. He loved the bird, saying that once they unloaded their bombs and "headed downhill" the Zeros over Rabaul couldn't keep up with them. I don't know exactly how accurate he was in that opinion, but that's what he claimed.


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## spicmart (Sep 11, 2016)

At least lookswise the B-26 edges out the B-25 by a mile. Its looks are that of a mean bastard, combining brutishness with yet a sleek appearance. An exciting plane. Of course I've read about its vices..
On the contrary the Mitchell looks like a boxy bore.

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## GregP (Sep 12, 2016)

I have never flown a B-25, but have several rides in ours. In all but one I was right behind the pilot. It operates light since we don't carry bombs or armament. At light weights it is definitely a short-field aircraft and accelerates quite well for a big airplane. John Maloney can get it off the ground with a very short run, but usually just waits for it to fly off. That is impressively short anyway at light weights. Everyone who flies it says it handles very nicely, but you CAN run out of up elevator in the landing flare. When you do (not if, but when), the solution is to add some power to bring the nose up. Optimal solution would be to have more weight in the tail, but anywhere near forward CG means low elevator authority at low speeds without power assist. Even so, it picks up little speed with flaps out and stops short.

Altogether a pleasant aircraft to fly according to all our B-25 guys. We also have an A-26 Invader, but no Maraduer, flying or otherwise, to compare it with directly.

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## Ascent (Sep 13, 2016)

A question on the B-26 handling, do we know what the British/Commonwealth pilots thought of it and whether it was considered a handful?


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## FLYBOYJ (Sep 13, 2016)

spicmart said:


> At least lookswise the B-26 edges out the B-25 by a mile. Its looks are that of a mean bastard, combining brutishness with yet a sleek appearance. An exciting plane. Of course I've read about its vices..
> On the contrary the Mitchell looks like a boxy bore.


So just because it "looks" better means its the better aircraft?!?!  While both aircraft performed well, the Martin B-26 disappeared pretty quickly after the war, that alone has to tell you something. The B-25 remained around for many years in secondary duties. Many people miss the fact that the "TB-25" was the standard USAF multi-engine trainer through out the 1950s, with the last one being retired in 1960.


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## Shortround6 (Sep 13, 2016)

Yep, A boxy bore, under wing bomb racks ( a few carried rockets) and one of the most heavily armed strafers ever built. 
A "J" with a solid nose and the top turret locked forward had *14 *.50 cal guns firing forward.

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## Old Wizard (Sep 13, 2016)




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## Balljoint (Sep 13, 2016)

And the B-25 was qualified for carrier service –well, at least one way.

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## Greg Boeser (Sep 13, 2016)

Yeah. The B-25 was a way better carrier based bomber than the B-26.
Maybe if you lashed both the _Hornet _and _Enterprise_ together end to end you could have gotten a B-26 airborne.


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## Greg Boeser (Sep 13, 2016)

Ascent said:


> A question on the B-26 handling, do we know what the British/Commonwealth pilots thought of it and whether it was considered a handful?


We can probably draw some assumptions by the fact that they passed it off to the Commonwealth so quickly.


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## FLYBOYJ (Sep 14, 2016)

Greg Boeser said:


> We can probably draw some assumptions by the fact that they passed it off to the Commonwealth so quickly.



Passed it off? The Commonwealth had a purchasing commission and didn't pick up seconds just because they were there. If i recall there were many commonwealth B-25s as well, these don't seemed to be "passed off" either.


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## GrauGeist (Sep 14, 2016)

There were quite a number of U.S. light and medium bombers "passed off" on the British...

Consolidated PBY = Catalina
Douglas A-20 = Boston/Havoc
Lockheed A-29 = Hudson
Lockheed PV-1 = Ventura
Martin A-30 = Baltimore
Martin B-26 = Maruader
North American B-25 = Mitchell

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## Micdrow (Sep 14, 2016)

Balljoint said:


> And the B-25 was qualified for carrier service –well, at least one way.



I assume you are talking about the Doolittle raid but the Navy later on did more experiments with the B-25 or known to the navy as the PBJ. As you can see by the pictures below from the book Squadron Signal B-25 in action book.

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## Micdrow (Sep 14, 2016)

Another thing most people don't know about is when the J models showed up in North Africa with the blister packs they actually removed the blister packs to save weight as they did not go down to the deck for strafing attacks like in the Pacific. Basically the guns where not needed for medium to high altitude bombing

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## Greg Boeser (Sep 14, 2016)

The same thing applied to MTO based B-26s.
In Europe the guns seem to have been left in place, but the only time I know of in which B-26s were allowed to strafe after the Ijmuiden attacks was Operation Clarion.


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## Balljoint (Sep 14, 2016)

Micdrow said:


> I assume you are talking about the Doolittle raid but the Navy later on did more experiments with the B-25 or known to the navy as the PBJ. As you can see by the pictures below from the book Squadron Signal B-25 in action book.
> 
> View attachment 352612





Micdrow said:


> I assume you are talking about the Doolittle raid but the Navy later on did more experiments with the B-25 or known to the navy as the PBJ. As you can see by the pictures below from the book Squadron Signal B-25 in action book.
> 
> View attachment 352612



 
Doolittle would have appreciated that option.


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## wuzak (Sep 15, 2016)

FLYBOYJ said:


> Passed it off? The Commonwealth had a purchasing commission and didn't pick up seconds just because they were there. If i recall there were many commonwealth B-25s as well, these don't seemed to be "passed off" either.



I assume he meant that aircraft purchased for the RAF were passed to the airforces of other Commonwealth nations, keeping the better ones for themselves.


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## GrauGeist (Sep 15, 2016)

wuzak said:


> I assume he meant that aircraft purchased for the RAF were passed to the airforces of other Commonwealth nations, keeping the better ones for themselves.


Outside of Britain, the only operators of the B-26 (aside from the U.S., of course) were France and South Africa.

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## Micdrow (Sep 15, 2016)

I started this thread back in 2007 but every once in a while update it but really needs an over haul but for those that are interested in B-25 weapons and other configurations.

B-25 weapons thread


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## Shortround6 (Sep 15, 2016)

The B-25 may have been slab sided but one could hardly call it boring.


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## Peter Gunn (Sep 15, 2016)

I like both of them, they both look equally deadly/cool in their own way. The PBJ in the lower right of Midcrow's post looks angry and about to go kick some tail. But if I had to pick I'd go with the B-25.


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## Norbert E. (Nick) Onaitis (Sep 16, 2016)

drgondog said:


> Changing a wing is a Big Deal. Period.


 Hi, The regularity of crashes by pilots training at MacDill Field-up to 15 in one 30-day period-is what led to the catchphrase, "One a day in Tampa Bay.The B-26 was also called: The Widowmaker". Other colorful nicknames included "Martin Murderer", "Flying Coffin", "B-Dash-Crash", "Flying Prostitute" (so-named because it was so fast and had "no visible means of support," referring to its small wings) and "Baltimore Whore" (a reference to the city where Martin was based).
According to an article in the April 2009 edition of _AOPA Pilot_ on Kermit Weeks' "Fantasy of Flight", the Marauder had a tendency to "hunt" in yaw. This instability is similar to "Dutch roll". This would make for a very uncomfortable ride, especially for the tail gunner. Fun, Fun, Fun! Pass the airsickness bags.
Personally, I wouldn't choose to fly in an aircraft that poorly designed.so bust me to A3C and put me to work painting rocks. I suppose that's one reason Martin later went belly up.
Nick


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## GrauGeist (Sep 16, 2016)

Martin didn't go belly up - postwar Martin stayed current with the aircraft industry, became involved in the growing aerospace industry and eventually merged with Lockheed.

And Lockheed Martin is very much alive and well today - one of their many current projects is the F-35.


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## spicmart (Sep 19, 2016)

FLYBOYJ said:


> So just because it "looks" better means its the better aircraft?!?!  While both aircraft performed well, the Martin B-26 disappeared pretty quickly after the war, that alone has to tell you something. The B-25 remained around for many years in secondary duties. Many people miss the fact that the "TB-25" was the standard USAF multi-engine trainer through out the 1950s, with the last one being retired in 1960.




I did not mean that it was a better aircraft, just the looks. I know it was phased out because that fast because the Mitchell could do practically everything the Marauder did as a less risky airplane with much lower unit cost. 
And I meant "boring" just compared to the looks of the B-26 not as an airplane per se.


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## ColdWarsChild (Mar 23, 2017)

Hello. A few years ago, when I worked for Lockheed Martin, I saw a story the company published bragging on the B-26. It sounded like hype, so, during my lunchbreaks, I'd search the internet about it and read about the controversies. It also made me curious about how the B-26 compared with the B-25, which is what this forum is all about. You have made many good points in your discussions, one of which was that the two aircraft were optimized after their debut for very different roles. In addition to that, the two aircraft came into existence through two very different paths, and that set the stage for how some of the later events turned out. Most of the information on which I am basing the following summary comes from YouTube videos by folks who were there at the time, not professional authors (if any of you want to find those videos, let me know and I'll see if I can find them again). What follows will be more about the development and modification of the aircraft than other considerations. So lets summarize the B-25 first, then the B-26. Summaries tend to be oversimplifications, but they are useful in serving as mental scaffolds on which details can be assembled.

In the 1930s, North American Aviation was serious enough about breaking into the military aircraft business that they built a new plant in Inglewood, California. They just needed to win some business. They entered their NA-39 design as the XB-21 in a competition against the Douglas B-18. A prototype was built and flown in December 1936. The performance of the XB-21 was far superior to the B-18, but the XB-21 cost $122,000 per aircraft and the B-18 cost $64,000 per aircraft. Douglas won. There was another chance with an Army Air Corps spec (circular proposal 39-640) in March 1938 that resulted in the NA-40. A prototype was built and flew in January 1939. Problems were corrected in the NA-40B which flew in March 1939. Competition was the Dougles DB-7 (which won as the A-20 Havoc), Stearman, and Martin, and the customers were Britain and France. There was another chance in an Army Air Corps spec in March 1939 that resulted in the NA-62. There was no time for a prototype, so the NA-62 was ordered off the drawing boards as the B-25. North American's previous prototype experience meant that the initial NA-26 design was close to being operational. Following the first production units, there was a design issue that had to be fixed - the wing dihedral. The word coming back from Britain was that bombers needed defensive armament, so that was another change. But very early into the long production, there was a B-25B that was combat ready. It had low wing loading which gave it a short take off roll. That plus its early maturity caused Jimmy Doolittle to choose it as the aircraft for the Tokyo raid. Going into production, North American put a lot of forethought into modular construction which lowered production costs, made field maintenance easier, and made modifications quicker. Because of the prototypes The B-25 was known for being very adaptable, and the modular construction facilitated this. Later in its combat life, the B-25 was optimized for low level attack using a lot of guns which caused lots of skin fatigue and fixing this became a recurring matinenance task. Some key features to remember: cheap to build and maintain, mature early, adaptable, short takeoff roll, forgiving to fly.

In 1932, Martin produced the B-10 which won the Collier trophy, made all other bombers at the time obsolete, and set standards for bombers which lasted for a decade. The B-10 introduced an all metal monoplane airframe, enclosed cockpits, internal bomb bay, rotating gun turrets, retractable landing gear, and full engine cowlings. It was even faster than the fighters of its day. For Martin, accomplishing this carried a lot of prestige. 121 were built. Now return again to the aforementioned to Army Air Corps spec (circular proposal 39-640) in March 1939. Martin entered Model 179 designed by Peyton Magruder, optimized for speed and range and payload with short, thin wings, high wing loading, high takeoff speed, and a long takeoff roll. Was the design pushing the edge too much to recapture prestige? Were the Army Air Corps and Magruder thinking flying faster than a fighter was achievable? Like the B-25 it was ordered right off the drawing boards - no time for a prototype. But there were no previous prototypes anything like the B-26 - it was very much an unproven concept. The initial production units were sent to the Pacific. They were a challenge to fly and to maintain. Then the same word came to the B-26 as to the B-25 about needing defensive armament. It, as well as torpedo racks, were added, and weight went up 2.5 tons. Pilot training was a Tampa Bay, and there were lots of crashes ("One a Day in Tampa Bay"). The Group Operations Officer investigated. Besides the known mechanical problems with carburetors, distributors, and prop feathering, he determined that inexperienced maintenance crews were causing some of the crashes. He took a B-26 up and simulated at altitude, landing conditions with loss of an engine. Result was an inverted spin that took 4000 feet of altitude to recover. His conclusion was that, as the B-26 was then, a pilot could not successfully takeoff or land on one engine. Problems got corrected. Jimmy Doolittle thought the the B-26 had the makings of a good bomber and got assigned the task of resurrecting its reputation. Eventually the B-26 got sent to England. The first raid was low level and the target was in Holland, and 4 aircraft wre lost. In the second raid, 11 aircraft were launched (one of which aborted). This was also low level and the target was in Holland, but they overflew more land, were attacked by fighters, were attacked by flak, and none of them returned. The B-26 was grounded. The same Group Operations Officer previously mentioned was part of a committee whose charter was to determine what kind of tactics changes were needed for the B-26 to be successful in Europe. The interviewed lots of experienced pilots from the theater and eventually decided, for protection against fighters, on an 18 aircraft box consisting of three sets of two Vs of 3 aircraft each. They flew at 12,000 feet (limited by having no oxygen aboard), and, until the bomb run started, changing direction every 15 seconds to avoid flak. Initially, their targets were the 23 enemy airfields. When operated this way, they had very accurate bombing and found that the B-26 could take a lot of punishment and still get them home. Surprisingly, it ended up with the lowest loss rate in the ETO for all the aircraft types. Some key features to remember: expensive, difficult maturation, narrow envelope but accurate bombing, long takeoff roll, could take a lot of punishment.


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## SANCER (Mar 23, 2017)

Very interesting information *ColdWarsChild*, the B-25 and Magruder are my favorite medium bombers; knowing more about its history is very enriching. I have a B-25G in 1/48, waiting to be armed.
By the way, welcome to the forum and enjoy so much and so much information, so many and many good friends and connoisseurs of military aviation.

Saludos cordiales 

Luis Carlos
SANCER


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## Greg Boeser (Mar 24, 2017)

Good summation, Coldwarschild. The reason Martin won the contract for the B-26 was because it pushed the envelope. North American came in second with a more conservative approach. As history would prove, the demands of war favored the more conservative approach. Perhaps if Martin had been given another year to refine the B-26, its faults could have been overcome. Peyton Magruder acknowledged that the decision to go forward with the short wing once it was obvious that the R-2800 wasn't going to develop the promised power in time was a major blunder. As it was, a promising aircraft became saddled with a bad reputation, which it never shook, even after it proved to be a very durable medium. By 1943, the medium bomber concept was considered obsolete in the USAAF.


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## tomo pauk (Mar 25, 2017)

Greg Boeser said:


> ... Perhaps if Martin had been given another year to refine the B-26, its faults could have been overcome. Peyton Magruder acknowledged that the decision to go forward with the short wing *once it was obvious that the R-2800 wasn't going to develop the promised power in time was a major blunder*. As it was, a promising aircraft became saddled with a bad reputation, which it never shook, even after it proved to be a very durable medium. By 1943, the medium bomber concept was considered obsolete in the USAAF.



(my bold)
I'd like to ask: what time, and what was planed power of the R-2800 for that time?


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## Greg Boeser (Mar 26, 2017)

Martin submitted multiple entries for the B-26 contract, powered by a variety of engines, including different configurations of the R-2600, the R-2800, and the R-3350, with different supercharger and turbocharger configurations. However, the Army chose the one with R-2800s with a single stage, two speed blower for the simple reason that it was production ready. The R-2800 was just entering production and the early A series -5 version was only rated at 1850 BHP takeoff. The original wing was optimized for high speed cruising, not lift, which resulted in a high stall speed, higher than the cruising speed of the previous generation of bombers. This meant that take-off and landing required more runway, and low speed flying was hazardous to inexperienced pilots. The B-26 program saw successive increases in weight from the initial design gross weight of 26,734 lbs to 28,600 lbs for the production B-26, 28,706 lbs for the B-26A, and 29,886 lbs for the first B-26Bs, entering service in May 1942. By April 1942 it was recognized that major changes were required to increase the safety and effectiveness of the B-26 program. The first stop gap change was to upgrade all further B-26Bs with the more powerful B series R-2800-41 and -43, developing 1920-2000 BHP for take-off. However, the remaining B-26B short wing production would receive modifications which pushed the normal gross weight to 31,165 lbs, higher than the initial design overload. The second, and more substantial change was the development of the longer wing, which first entered service in August 1942 with the B-26C-5 produced in Omaha, and later the B-26B-10 produced in Baltimore. By the time these fixes were fielded, the high accident rate and the delays caused by the safety investigations and production changes had given North American a huge lead in production, and done permanent damage to the Martin reputation. The low combat loss rate achieved in '44 and '45 came too late to save the B-26. By mid '43 it was considered obsolescent, and no further modifications were to be made except those which simplified production.


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## Shortround6 (Mar 26, 2017)

The real question is what version/s of the R-2800 did Martin *want* to use?
Which versions would have delayed production 6 months to a year? 
What versions was P & W promising in 1939 and what delivery dates? 
Adding two stage superchargers or turbos to the "A" series engine would have done *nothing *for take-off power and added several hundred pounds of weight to each engine. Would have done the same thing to the "B" series engines too, which does absolutely zero for the take-off/landing problem.


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## tomo pauk (Mar 26, 2017)

Greg Boeser said:


> Martin submitted multiple entries for the B-26 contract, powered by a variety of engines, including different configurations of the R-2600, the R-2800, and the R-3350, with different supercharger and turbocharger configurations. However, the Army chose the one with R-2800s with a single stage, two speed blower for the simple reason that it was production ready. *The R-2800 was just entering production and the early A series -5 version was only rated at 1850 BHP takeoff.* The original wing was optimized for high speed cruising, not lift, which resulted in a high stall speed, higher than the cruising speed of the previous generation of bombers. This meant that take-off and landing required more runway, and low speed flying was hazardous to inexperienced pilots. The B-26 program saw successive increases in weight from the initial design gross weight of 26,734 lbs to 28,600 lbs for the production B-26, 28,706 lbs for the B-26A, and 29,886 lbs for the first B-26Bs, entering service in May 1942. By April 1942 it was recognized that major changes were required to increase the safety and effectiveness of the B-26 program. The first stop gap change was to upgrade all further B-26Bs with the more powerful B series R-2800-41 and -43, developing 1920-2000 BHP for take-off.
> ...



(my bold)
I appreciate the post. Still it is apparent to me that Marguder was pointing the finger in wrong direction (to P&W, that were developing and delivering engines of promissed power on schedule), instead of to the direction. Namely, on himself - going for thick, but small wing will be detrimental to low speed handling, while not conductive to the realy high speed. Mr. Marguder didn't see fit to install Fowler flaps on the B-26, a great thing to circumevent the limitations of a small wing.
The fuselage was designed to give enough of room for several crew memebers to go to and from, eg. the navigator and radio-man were to crawl back and man the machine guns. Thus the size and hence weight of fuselage (and of whole aircraft) went over-board.
BTW - the engine with 'only 1850 HP for take off' in 1941 is a world-beater when it is about take off power; the Do 217E was doing everything as well as the early B-26 on 2*300 HP less in same year. While being without low-speed vices.


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## Greg Boeser (Mar 26, 2017)

It seems that Magruder was designing with an eye toward the future. The fuselage was designed with plans for pressurization in later versions. He hoped for engines with features that were in 1939 only in the planning stages. And he deliberately sacrificed low speed handling in a bid for more speed by reducing drag to a minimum. The symmetrical airfoil he employed was touted at the time to be the most drag efficient shape. This was used for the wing, the fuselage and the engine nacelles to the greatest extent possible. One could argue that he designed for the test. While North American upsized their NA-40 design to try to meet the requirements of the Air Corps Proposal 39-640, Martin started from scratch. Their design won because it met or exceeded more requirements than the NA-62. The Air Corps circular made no requirements for low speed handling, so Magruder didn't worry about it. The requirement called for a large bomb load, and specified that 30 x 100 lb bombs were one configuration that must be carried. Magruder copied the B-17 bomb bay, which had 20 stations, that could hold up to 4000 lbs of larger bombs, and then added a second bay to hold the rest of the required 100 pounders. This determined the width of the circular fuselage. North American elected to only partially meet the 3000 lb payload requirement, creating a narrower bomb bay that could hold 3 x 1000 lb bombs, but fewer smaller bombs than required. As designed, the Martin 179 was bigger, faster and could carry more bombs than the NA-62. Its drawbacks were the poor low speed performance, and a complicated production process which demanded special machines and more man hours than the simpler NA-62. The 179 relied on many unproven design features that had to be "debugged" before they would give the best performance, while the NA-62 relied on technology that was already proven. The development arc of the two models shows that North American's conservative approach paid off in that later developments were designed to improve performance in range and payload, whereas Martin's development dealt with trying to overcome the inherent low speed shortcomings of its design. Martin's changes led to a reduction in overall performance by reducing speed and maximum bomb load in a bid to improve the poor low speed performance. By the end of production, whatever performance lead the B-26 had originally had over the B-25 had been lost.

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## tomo pauk (Mar 27, 2017)

Thank you for the overwiev.

This is supposed to be the table of proposed variants for the Martin Model 172 (for the Circular Proposal 39-640),depending on type and variant of American big radial engines; the USAAC/AAF choice was bid No.6 (= powered by the only available production variant of the R-2800 for 1941):

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## Greg Boeser (Mar 27, 2017)

Cool! I've never seen the actual chart before.


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## wuzak (Mar 28, 2017)

tomo pauk said:


> (my bold)
> I appreciate the post. Still it is apparent to me that Marguder was pointing the finger in wrong direction (to P&W, that were developing and delivering engines of promissed power on schedule), instead of to the direction. Namely, on himself - going for thick, but small wing will be detrimental to low speed handling, while not conductive to the realy high speed. Mr. Marguder didn't see fit to install Fowler flaps on the B-26, a great thing to circumevent the limitations of a small wing.
> The fuselage was designed to give enough of room for several crew memebers to go to and from, eg. the navigator and radio-man were to crawl back and man the machine guns. Thus the size and hence weight of fuselage (and of whole aircraft) went over-board.
> BTW - the engine with 'only 1850 HP for take off' in 1941 is a world-beater when it is about take off power; the Do 217E was doing everything as well as the early B-26 on 2*300 HP less in same year. While being without low-speed vices.



I have been reading a book about the Avro Manchester.

It too had several weight increases through the design and prototype phase, but in their instance the wings also grew.

The really interesting thing is that the Manchester was a much larger aircraft than the B-26, had an all-up-weight around 18,000lb greater than the B-26 but still had the same take-off power - 2 x 1,850hp (and the added bonus that the Vulture was somewhat less reliable).


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## Zipper730 (Mar 28, 2017)

tomo pauk said:


> Thank you for the overwiev.
> 
> This is supposed to be the table of proposed variants for the Martin Model 172 (for the Circular Proposal 39-640),depending on type and variant of American big radial engines; the USAAC/AAF choice was bid No.6 (= powered by the only available production variant of the R-2800 for 1941):
> 
> View attachment 369640


So Bid #5 was not picked because the engine was not available?


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## Shortround6 (Mar 28, 2017)

Among other reasons. BTW the engine in option 4 didn't exist either in 1939. 
The turbo R-2600 flew in a few A-20s and gave nothing but trouble. 
The two stage R-2600 flew for a few weeks in the prototype F6F in 1942. They swapped it for a 2 stage R-2800. 
Actual number of flyable R-3350s in 1939/40 for options 12.13.14 and 15 were either slim or non-existent. 

At the time of this proposal these were the engine options _expected _to be available 2-3 years *in the future. *


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## Greg Boeser (Mar 28, 2017)

So, Wuzak, I suppose if Magruder had doubled the wing area, the Marauder could have done the work of a Manchester.
Interesting parallels: 202 Manchesters were built; 201 B-26 MA were built. Manchesters served with eight squadrons plus two others non operationally; B-26 MAs served operationally with six squadrons plus two groups non-operationally. Production of the Manchester was halted in November of 1941 in favor of the Lancaster; production of the B-26 MA was halted in November 1941 in favor of the B-26A, which was superceded in March 1942 by the B-26B.


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## wuzak (Mar 29, 2017)

Greg Boeser said:


> So, Wuzak, I suppose if Magruder had doubled the wing area, the Marauder could have done the work of a Manchester.



What, be overweight and under-powered?

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## Robert Porter (Mar 29, 2017)

wuzak said:


> What, be overweight and under-powered?


Hmmmm, I resemble that remark!


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## Greg Boeser (Mar 30, 2017)

It comes with age.

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## Zipper730 (Apr 4, 2017)

Shortround6 said:


> Among other reasons. BTW the engine in option 4 didn't exist either in 1939.
> The turbo R-2600 flew in a few A-20s and gave nothing but trouble.


The R-2800 did fly in 1940 on the XF4U...


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## Shortround6 (Apr 5, 2017)

The two stage engine that flew in the XF4U-1 in the end of May 1940 was rated at 1800hp for take-off,it was the X-2 model. At some point it was replaced by the X-4 engine with 1850hp for take-off. Production F4Us used 2000hp engines. The X-4 engine corresponds to the engine in option #6. 
I don't know if the engine in option #4 ever flew in a test hack but it didn't fly in any service aircraft or prototype until the first flight of the XF6F-1 on June 26th 1942. 
The proposals listed in the chart provided by Tomo were made in the end of June 1939. 
First flight of an R-2800 with *any *type of supercharger was at the end of July 1939. 
On Aug 10th, 1939 the Army ordered 201 B-26 bombers. They were taking quite a gamble on the R-2800 as it was. Basing a design on engines that were even further from flight status and more complicated was an even bigger gamble. One that the Army was apparently not willing to take. 
First flight of a B-26 was November 25, 1940 and at this point there 1131 aircraft on order.


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## Greg Boeser (Apr 5, 2017)

This is fascinating stuff. The more you dig, the more you realize that the B-25 was the fall back option if the B-26 failed. I wouldn't say that the B-26 was a failure, but, the fact that the B-25 was available when the early B-26 ran into difficulties made the decision to go ahead with the B-25 a wise one in retrospect. It had never occurred to me, but the Army went with NAA's NA-62 bid that used the R-2600 for the same reason that Martin was told to use the R2800-5, because it would be available in sufficient quantity to ensure production deadlines.


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## Conslaw (Apr 7, 2017)

It looks like the US hedged its bets with virtually all aircraft types, having at least two options. On the naval side of thing this proved to be even more important than the Army. Having the F4F-3 as an alternative to the F2A-3 was crucial. Having the F6F available for carriers earlier than the F4U - crucial. Building the SBD as a stopgap before the SB2C, again crucial. In cases like the B-25 and B-26 (as well as the B-17 and B-24), both types performed well, but by producing both, we were able to get more plants online and put more people on the job. We were also able to use different engines in each, spreading the risk that if one engine type was problematic, the war effort wouldn't suffer. 

I think it would be good for the F-35 to have some competition. Ideally, that competition should have been from the start, but I think it's time to start a new program, learning from mistakes made with the F-35. 

(Before F4U fanboys flame me. I'm not suggesting it was a bad plane, I'm just saying that it was good that the F6F was available for carriers while the Corsair's bugs were being worked out. Having 12,000 of each was a nice luxury.)


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## pbehn (Apr 7, 2017)

I would say that hedging bets is a wise strategy if you can afford the luxury. It is only in hindsight that we know how long each took to get into service. In practice they (Corsair and Hellcat) had different strengths and weaknesses which is a plus provided you have enough.

There are few "fanboys" here, however there are some real experts on aviation history.


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## FLYBOYJ (Apr 7, 2017)

Conslaw said:


> I think it would be good for the F-35 to have some competition. Ideally, that competition should have been from the start, but I think it's time to start a new program, learning from mistakes made with the F-35.



1 - the F-35 did have competition, it was called the X-32
2 - not to say the F-35 didn't have issues (most exaggerated) but the only new program that needs to started is a way to recycle the debris left behind after an F-35 strike (to include opposing aircraft).

Sorry to hijack the thread, we do have an F-35 thread that has up to date information on this aircraft.

“Red Flag confirmed F-35 dominance with a 20:1 kill ratio” U.S. Air Force says

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## Madelman (Oct 13, 2018)

Very interesting discussion on bombers. I've learned a lot as always in this forum

But I still have a doubt, did the B-26A really need a wing increase? with the initial wing and being careful with weight increase, would have been viable to keep the B-26 faster?

Imagine that you change the training procedures to reduce crashes


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## Shortround6 (Oct 13, 2018)

Well, you run into two (at least) conflicting problems by keeping the weight low.
1. was defensive armament, The initial B-26 model/s weren't badly armed for 1941/early 1942 but they sure weren't well armed either. That power operated twin 
.50 on top was well ahead of world standard _but _it only had 200rpg. The extra 200rpg fell into the overload weight catagory let alone carrying any extra. The single .50 out the tail (without power assist) also didn't have much for ammo(200rounds). As for the single .30 in the nose the the single .30 out the ventral hatch? The 5 man crew was a bit of joke too. 4 gun positions, 5 men, no co-pilot when the guns are manned?
IS the _fast_ B-26 fast enough not to need the heavier defensive guns? 
2. And this is the real heart of the matter. The B-26 only hit those high speeds when carrying a small (2000lb) bombload and not much fuel, The 326mph figure was supposed to be at 26,734 pounds. 
According to the manual with 2000lb of bombs and 465 gallons of fuel the plane weighed 28,706lbs. so either the 326mph speed is good for _after_ the bombs are dropped _or_ you only have about 130 gallons of fuel to get home with.
With full tanks (962 gallons in the wings) and with 4000lbs of bombs weight could hit over 33,000lb on the early planes. 

How they were to be used in operation I don't know but if you want to keep the high speed your bomb/range combination doesn't look a whole lot better than an A-20. 
One the B-26B the tail armament installation went from 161.3 pounds to 1135.7 pounds but included 3000 rounds of ammo. Normal gross (2000lb of bombs and 465 gallons of fuel) went up 1180 lbs on the B-26B (early ones).

Once the planes get to combat zones are the commanders going to be happy with the light bomb load and short range?

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## Greg Boeser (Oct 13, 2018)

The thing to remember is that the small wing area of the B-26 was based on the belief that it would be getting more powerful engines. When the USAAF formalized the contract they specified the R-2800-5 at 1850 bhp. Which was the most powerful engine available at that time. The design gross weight was 26,740 lbs, but soon operational considerations pushed the actual weight higher. The addition of a powered turret, self sealing fuel tanks and armor pushed the weight to 28,706 lbs combat weight for the early B-26 and B-26A, 29,886 lbs for the early B-26B. These numbers were the design weight based on a five man crew, 2000 lbs of bombs and 465 gallons of fuel. Take-off weight with full fuel tanks adds another 3000 lbs. Combat units in the Pacific operated with seven man crews (+400 lbs), added .30 caliber waist guns (+150 lbs) and later upgraded the .30 caliber guns to .50 caliber (+170 lbs.) 
Meanwhile back in the States, the training establishment is throwing tyro pilots into them straight out of flight school and suffering astronomical crash rates. The quick answer seems to be - increase lift by increasing wing area. Weight reduction was suggested as an option by the combat units, but the Material Command was already pushing for greater increases in defensive armament and armor. By late 1942, short wing B-26Bs fitted with the slightly more powerful R-2800-41 and -43 had a gross weight 31,165 lbs, an increase of nearly 4500 lbs.
Max take-off weight was restricted to 36,500 lbs. G-load restrictions kicked in a 31,000 lbs. so at combat weight, the B-26 is already overweight.

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## Greg Boeser (Oct 13, 2018)

Shortround6 said:


> Once the planes get to combat zones are the commanders going to be happy with the light bomb load and short range?


 COMSOPAC regarded the B-26B an uneconomical plane, and felt that its role could be performed by P-38s. It should be noted that their experience was with the early R-2800-5 equipped B-26B, further weighed down by the addition of package guns.

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## davparlr (Oct 13, 2018)

Shortround6 said:


> Well, you run into two (at least) conflicting problems by keeping the weight low.
> 1. was defensive armament, The initial B-26 model/s weren't badly armed for 1941/early 1942 but they sure weren't well armed either. That power operated twin
> .50 on top was well ahead of world standard _but _it only had 200rpg. The extra 200rpg fell into the overload weight catagory let alone carrying any extra. The single .50 out the tail (without power assist) also didn't have much for ammo(200rounds). As for the single .30 in the nose the the single .30 out the ventral hatch? The 5 man crew was a bit of joke too. 4 gun positions, 5 men, no co-pilot when the guns are manned?
> IS the _fast_ B-26 fast enough not to need the heavier defensive guns?
> ...


No, I do not agree. In another post, I normalized a B-26B-2 short wing with a B-26B-10 long wing, in load carrying (fuel/weapons), horsepower (1400 hp) and altitude (5000 ft) the results was that the -2 was at least 20 mph faster than the -10 according to flight test results of numbered identified aircraft. Additional equal load-outs added to both would most likely not affect this airspeed advantage. 20 mph faster cruise would give a crew 20 minutes less exposure to enemy airspace for 300 mile deep penetration strike. In addition, fighter planes would take longer to intercept and, in the process, use more precious fuel to catch, fuel they usually have little of. If you don't think 20 mph is significant, imagine driving on the interstate (we call them freeways here in California) at 70 mph and some one passes you at 90 mph. I bet at first you would say,wow that guy is really driving fast. That would represent the B-26B-2 short wing passing a B-26-10 long wing. Speed is life.

In my opinion the biggest drawback of the short wing would be the need for longer runways.

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## Greg Boeser (Oct 13, 2018)

Combat comparisons of B-26s and B-25s in North Africa during the short wing era (December '42 to June '43) gave a huge advantage to the B-25. The B-26 was more maintenance intensive and the higher landing and take-off speeds resulted in more crashes. The speed differential was not considered significant because a 375 mph fighter could catch either one. The B-26 was also harder to handle on one engine. The low combat loss reputation of the B-26 did not emerge until the introduction of the long wing. Which also benefitted from better trained crews, better escort, better defined mission envelope (large formations - 24 - 36 a/c at medium altitude, heavily escorted), and weakening opposition.
Remember the loss rate for 8th AF short wing B-26Bs was .44 per sortie. OK, a bit of an exaggeration, a few short wing Bs soldiered on in the Eighth after May '43, but by resumption of operations in July, nearly all Marauders were long wing Bs and Cs.

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## Shortround6 (Oct 14, 2018)

davparlr said:


> No, I do not agree. In another post, I normalized a B-26B-2 short wing with a B-26B-10 long wing, in load carrying (fuel/weapons), horsepower (1400 hp) and altitude (5000 ft) the results was that the -2 was at least 20 mph faster than the -10 according to flight test results of numbered identified aircraft. Additional equal load-outs added to both would most likely not affect this airspeed advantage. 20 mph faster cruise would give a crew 20 minutes less exposure to enemy airspace for 300 mile deep penetration strike. In addition, fighter planes would take longer to intercept and, in the process, use more precious fuel to catch, fuel they usually have little of. If you don't think 20 mph is significant, imagine driving on the interstate (we call them freeways here in California) at 70 mph and some one passes you at 90 mph. I bet at first you would say,wow that guy is really driving fast. That would represent the B-26B-2 short wing passing a B-26-10 long wing. Speed is life.
> 
> In my opinion the biggest drawback of the short wing would be the need for longer runways.



My problem with this is that there were some other changes between the B-2 and the B-10. Some were subtle and some not so subtle but somehow the change in the wing gets all the credit (blame). There were a bunch of changes between the B-26/A and the B-26B-2 that also cost speed. 
engine on a B-26A 




original picture by Andrew Baird
Engines on a later B-26




The Spinners went away on the very early Bs. The oil cooler inlets got bigger, On the B-3s the air intakes got much bigger in order to accommodate sand filters. Now if the four package guns cost 3-5mph (or 3% of range, sources differ) what did all the changes to the engine installation cost? 



[Squadron-Signal] 
Please notice that the vertical stabilizer and rudder grew about 1ft 6in from the small wing to the big wing.
I haven't seen what this cost in speed and it may be lumped in the cost of the big wing. 
It is said that the larger fin and rudder were needed to stabilize the bigger wing but I am at least somewhat sure that having a bigger fin and rudder helped in an engine out situation. 
At some point the horizontal stabilizer and elevators got bigger too, but I don't know when. 

A problem with a B-26 doing a 300 mile deep penetration strike (or even a 150 mile radius in enemy territory) is the amount of fuel required. A B-26 used 350-400 gallons an hour at max continuous depending altitude/supercharger gear and so on. Backing down to 75% power gets you (at least on the very early B-26) a cruise of just under 280mph at 8,000ft while burning around 270-290 gallons an hour. IF for instance you drop bombs at 250 miles from base and you figure 150 miles of that is enemy territory then you need about 200 gallon at bombs gone (cruise can be dropped to around 200mph and a fuel burn of close to 100gph once in friendly territory) and this means entering enemy territory with at least 350 gallons in the tanks. Now please note this takes into account NO deviations in flight path (even a several mile turn around at the target), NO reserves , Runway is lined up with the target and NO use of power above 75% even for 1 minute. 

The QUestion in post #34 from a new member was 


Madelman said:


> But I still have a doubt, did the B-26A really need a wing increase? with the initial wing and being careful with weight increase, would have been viable to keep the B-26 faster?
> 
> Imagine that you change the training procedures to reduce crashes



Some of the changes that slowed the B-26 down had little to do with the wing increase. While you could be a bit careful with the weight increase (did the tail gunner on the B-26B really need 1500 rounds per gun? perhaps 700-800 would have done the job? ) some was inevitable. ANd it started a spiral.

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## Greg Boeser (Oct 14, 2018)

Early users of the B-26B (69th and 70th BS in South Pacific) did recommend reduction in the ammo for the rear guns. 70th BS reduced the load to 400rpg and moved the ammo canisters back to just forward of the bulkhead separating the tail gunner position from the rest of the fuselage. This was done to reduce weight and reduce the vulnerability of the feed chutes. Later, with the adoption of the M6 tail turret on the -20 blocks of the B and C, the ammo load was standardized at 800 rpg. Of course the weight of the hydraulic turret increased the tail heavy aspect of the aircraft, which led to the twisted wing on the F and G models. This increased drag and reduced top speed. But then again, trimming to correct for the tail heaviness probably was responsible for some of the speed loss in earlier models. Too bad the proposed E model modifications were not approved. Moving the top turret forward, as done with the later models of the B-25, and the installation of roll up bomb doors like on the B-24 would have improved CoG problems and reduced drag. Open bomb doors reduced speed by up to 25 mph.

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## davparlr (Oct 16, 2018)

Shortround6 said:


> My problem with this is that there were some other changes between the B-2 and the B-10. Some were subtle and some not so subtle but somehow the change in the wing gets all the credit (blame).


Changes between the B-10 to the B-25B-2 include:
Larger cowling intakes for new engines*
Four added .50 cal machine guns- two added .50 cal to fuselage side hatches, one .50 cal added to nose, two package .50 cal added*.
Ventral .50 cal machine gun removed
Various internal mods

automatic life raft ejector
Day and night drift signals (?)
Inclinometer
Astrocompass
Astrograph
New Starter
Winterization equipment (?)
Lengthened nose wheel strut
Mechanically operated gear doors (?)
Slotted flaps
Rudder/vertical stabilizer increase*
* Changes that affect aerodynamic performance not including wing span increase . It is my opinion that all these changes put together would have an almost imperceptible impact to the overall form drag of the B-26.
Wing span extension from 65 to 71 feet,
Empty weight increased from 22,380 lbs to 24,000 lbs, or 1600 lbs. I would guess that the non-wing extension weight increases as between 200-300 lbs (the entire tail structure of the P-47 was 250lbs) which would make the wing extension 1300-1400 lbs.




> There were a bunch of changes between the B-26/A and the B-26B-2 that also cost speed.
> engine on a B-26A


I was not interested in the B-26A, I was interested in two aircraft configurations that were close but with different wings in order to isolate the performance degradation of the wing extension alone. The B-26B-2, represented all the configurations prior, and the B-26B-10, which is basically the base for follow on models. And, I had flight test results of these two aircraft.



> The Spinners went away on the very early Bs. The oil cooler inlets got bigger, On the B-3s the air intakes got much bigger in order to accommodate sand filters. Now if the four package guns cost 3-5mph (or 3% of range, sources differ) what did all the changes to the engine installation cost?


Neither the B-26B-2 nor the -10 tested had spinners. Also, apparently the -10 only had two package guns, per Mendenhall’s Deadly Duo.


> Please notice that the vertical stabilizer and rudder grew about 1ft 6in from the small wing to the big wing.
> I haven't seen what this cost in speed and it may be lumped in the cost of the big wing.
> It is said that the larger fin and rudder were needed to stabilize the bigger wing but I am at least somewhat sure that having a bigger fin and rudder helped in an engine out situation.
> At some point the horizontal stabilizer and elevators got bigger too, but I don't know when.



Don’t know much about this. I think the added size of the vertical stabilizer, or the package guns, would be very small relative to the form drag of a pretty large bomber.



> A problem with a B-26 doing a 300 mile deep penetration strike (or even a 150 mile radius in enemy territory) is the amount of fuel required. A B-26 used 350-400 gallons an hour at max continuous depending altitude/supercharger gear and so on. Backing down to 75% power gets you (at least on the very early B-26) a cruise of just under 280mph at 8,000ft while burning around 270-290 gallons an hour. IF for instance you drop bombs at 250 miles from base and you figure 150 miles of that is enemy territory then you need about 200 gallon at bombs gone (cruise can be dropped to around 200mph and a fuel burn of close to 100gph once in friendly territory) and this means entering enemy territory with at least 350 gallons in the tanks. Now please note this takes into account NO deviations in flight path (even a several mile turn around at the target), NO reserves , Runway is lined up with the target and NO use of power above 75% even for 1 minute.


I don’t really want to dig into this and, knowing you, I doubt if I could identify an error. However, the salient point is that the B-26B-2 has a lower drag value than the B-26B-10. Therefore, for any given mission, the B-26B-2, vs. the -10, could fly at the same speed with less power therefore use less fuel, therefore more bombload? Or could fly the same mission with the same power setting and fly faster. And since it will fly the mission faster at the same power level, it would use less fuel, therefore more bombload?

Test at approx. *5k ft*.
B-26B-2, AC 41-17756, *airspeed 281 mph*, *1400 hp/eng,*, test weight *29,860* lbs
B-26B-10, AC 41-18199, airspeed *250 mph*, *1400 hp/engine* est. (247mph/1325hp), wt *30,780* lbs

Notes: Since the added wing span is most likely over 1,000 lbs, the two test weights should represent identical load carry capacity.

Miscellaneous issues mentioned above, and a few others including cowl flaps have an impact on these test. Including these, I estimated the difference in airspeed at 5000 ft, 1400 hp power setting and equivalent weight to be *reduced from 31 mph to 20 mph.*

If any modification, e.g. electro-hydraulic tail gun, to the -10 that led to later configurations up to B-25C were applied to the -2 configuration, i.e. short wing, the results would be the same in that the -2 configuration would be faster at the same power levels just because it was just cleaner.


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## fliger747 (Oct 21, 2018)

As to flying the B-26, it was faster on takeoff and landing, enough so that a different frame of mind was needed. Remember that these pilots trained and transitioned from such slower aircraft. Almost like the transition to jets. I transitioned to jets from C130's which maybe had sort of B-29 weight and speeds so not so bad after a long sim program under experienced tutelage. This was war time, no such luxuries and the military aviation was very much a swim or sink proposition. In USN basic flight training of the time my father said they lost about 5% killed... 

Not that it makes much difference but I did the flight dynamics for a B-26 available for Flightsim and thought it much more like approaching with a jet, at least in my interpretation. Speed is life in this case and loss of an engine on a balked landing when low and slow and cobbing the power to it for the go around is definitely a ragged edge of the envelope requiring decent skills. Low time pilots... Most of the WWII aviators could have used more and better training, a luxury and the loss rate was considered acceptable. 

With good trading and experience, a good airplane, the B-26. The low loss rate speaks to this.

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## tomo pauk (Oct 21, 2018)

fliger747 said:


> ...
> With good trading and experience, a good airplane, the B-26. The low loss rate speaks to this.



Target choice, escort available - those two factors need to be factored in, too. Had nothing to do with specific aircraft, the B-26 benefitted through these. We know that un-escorted B-26 (as well as most of other bombers) will be cut to pieces when attacking in daylight, say, targets around Frankfurt area.


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## fliger747 (Oct 21, 2018)

The point being that they weren't crashing outlandish numbers operationally. Probably more Bf 109's bit the dust in takeoff and landing accidents than to air combat. 

Speaking of Frankfurt, my co pilot (ex Edwards Test Pilot) and I were standing on a bridge in the middle of the Main and an old german galoot comes up and starts blazing away at us in german. I'm getting about half of it, all the local stuff bombed starting with the bahnhof the talks about the Amerikanish Panzers rolling into Sachenhausen. Then he blurts out "Unt das Holocaust vas ein Schwindle"....

Cheers: T


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## tomo pauk (Oct 21, 2018)

fliger747 said:


> The point being that they weren't crashing outlandish numbers operationally. Probably more Bf 109's bit the dust in takeoff and landing accidents than to air combat.
> ...



Let's not move the goal post. 
Phrase 'the low loss rate speaks to this' is a world away from 'they weren't crashing outlandish numbers operationally '. Loss rate has plenty to do with enemy encountered (or not), capability of enemy Flak, targed type and distance, while operation crashes are much more related to the flying qualities of a selected A/C.


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## davparlr (Oct 22, 2018)

fliger747 said:


> As to flying the B-26, it was faster on takeoff and landing, enough so that a different frame of mind was needed. Remember that these pilots trained and transitioned from such slower aircraft. Almost like the transition to jets. I transitioned to jets from C130's which maybe had sort of B-29 weight and speeds so not so bad after a long sim program under experienced tutelage. This was war time, no such luxuries and the military aviation was very much a swim or sink proposition. In USN basic flight training of the time my father said they lost about 5% killed...
> 
> Not that it makes much difference but I did the flight dynamics for a B-26 available for Flightsim and thought it much more like approaching with a jet, at least in my interpretation. Speed is life in this case and loss of an engine on a balked landing when low and slow and cobbing the power to it for the go around is definitely a ragged edge of the envelope requiring decent skills. Low time pilots... Most of the WWII aviators could have used more and better training, a luxury and the loss rate was considered acceptable.
> 
> With good trading and experience, a good airplane, the B-26. The low loss rate speaks to this.


When did you transition from C-130s to jets? Back in the 50s I believe the Navy had a real problem with safety. I grew up in Pensacola where at the time the Lexington was stationed for carrier quals. It seemed like every time the Lex went out for quals it would lose a plane and pilot. I lived on the approach end of NAS runway and there were several wrecks out in the woods, mostly SNJs, one F9F. I think they started a rigorous safety program and cleaned up their act.


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## YF12A (Oct 26, 2018)

My neighbor flew just about everything, including both the B-25 and the B-26. He told me the B-26 was not as easy to fly and definitely took more training to be safe in it. Said the same thing about the B-24 compared to his all time favorite, the B-17. He kept current in the B-25, among other aircraft when stationed at the Pentagon in the '50's and loved flying it and said it had better visibility as well. This is from someone with 8,500 hours in the USAAF/USAF.


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## Greg Boeser (Oct 26, 2018)

That is an apt comparison. The B-24 vs B-17 and B-26 vs B-25 debates have many similarities. Both the B-24 and B-26 were more complex than their rivals, and were at least on paper better performers, but the ease of handling and easier serviceability of the B-17 and B-25 gave them an edge operationally. Accident rates were much higher for the B-24 and B-26 compared to their stable mates.


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## Zipper730 (Nov 23, 2018)

I guess building in an intercooler would have been harder to do even when the twin-stage superchargers became readily available for operational use in the US?


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## tomo pauk (Nov 23, 2018)

Zipper730 said:


> I guess building in an intercooler would have been harder to do even when the twin-stage superchargers became readily available for operational use in the US?



For what engine?


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## swampyankee (Nov 23, 2018)

On the other hand, the B-24 has better payload-range characteristics than the B-17, so it had uses, such as maritime patrol, that the B-17 could not do as well. 

The B-26 had worse payload-range than the B-25, so there would seem very little advantage to the B-26.


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## Zipper730 (Nov 23, 2018)

tomo pauk said:


> For what engine?


R-2800, twin-stage supercharger


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## tomo pauk (Nov 23, 2018)

Zipper730 said:


> R-2800, twin-stage supercharger



Intercooler was present there from day one.


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## Shortround6 (Nov 24, 2018)

A text book from 1942/43 claimed that an estimated 10 cubic feet of space was needed for an intercooler installation for a 1000 HP engine. Due to economy of scale you don't need 20 cubic feet for a 2000 HP engine but you do need a lot more than ten. This makes it rather difficult to add 2nd stages and intercooler to existing designs.
Please look at the B-24 for an extreme example. Originally designed and built without the turbo with a round cowling, when the turbo was added the cowling was changed to the oval shape with large scoops/intakes on both sides. One side is the combined intake air and oil cooler. The other side is entirely cooling air for the air cooler.
Adding 2 stage supercharger to an airplane will improve it's performance above 15,000 ft or so but hurt it under that height, unless your fuel/engine will allow for lots over boost.
Most radials were severe duty engines for fuel and did not tolerate over boost well without water injection.

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## Greg Boeser (Nov 24, 2018)

The B-26 had better internal payload. The B-25 could only surpass the B-26 payload by carrying ordnance externally. 
The B-25 did have better range once its internal tankage was upped to 975 US gal. R-2600s having far better fuel economy than R-2800s.


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## MIflyer (Nov 24, 2018)

I read recently that in 1943 the USAAF made the decision to use the B-25 as its primary multi-engined trainer, replacing the AT-9, AT-11, AT-21, etc. It was considered to be so easy to fly and so reliable that it made a better trainer than did the trainers, and of course it was good for other things, too, and often served as a hack both during and after the war. The B-25 continued to be a trainer after the war, all the way until the late 1950's. Gen Doolittle had a B-25 as his personal transport until well after the war, one modified to use the much quieter collector ring exhausts of the early models.

A book by a B-26 navigator in the ETO revealed that they avoided losses by following the recommendations of the RAF and making frequent course changes when flying over occupied territory, every 3 minutes or so, preventing the Germans from setting up an AAA barrage. The only units I know of that used a B-26 as a hack were those that transitioned to A-26's and kept one of their old B-26's since it had more room for cargo and people.


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## tomo pauk (Nov 24, 2018)

Greg Boeser said:


> The B-26 had better internal payload. The B-25 could only surpass the B-26 payload by carrying ordnance externally.
> The B-25 did have better range once its internal tankage was upped to 975 US gal. R-2600s having far better fuel economy than R-2800s.



R-2600-13, as found on B-25s, consumed between 90 and 100 USG/hr at 2100 rpm, lean mixture*; 115 USG/hr at rich mixture. The R-2800 of 1850 HP, as found on early B-26, was consuming between 70 and 80 USG/hr at 2150 rpm**. The smallest consumption figure I was able to find is 38.5 USG for the R-2800 (at 1480 rpm), and 31 USG/hr for the R-2600-13, however that was listed under 'conditions to avoid' (that particular consumption was for 1600 rpm, 29.5 in Hg, at sea level).

* making 1005 or 905 HP, 1st or 2nd S/C gear
** making 900 or 975 HP, 1st gear only


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## Greg Boeser (Nov 24, 2018)

OK, but only the B-26 MA (201 made), the B-26A (139 made) and the first 80 or so B-26Bs used the lower rated engine. All B-26Bs, Cs, Fs & Gs used in NA and Europe used the more powerful, and thirstier, R-2800-41(B-26B and B-2) and R-2800-43 (B-26B-3 and later).
By the way, I have copies of several B-26 manuals and each presents the fuel consumption numbers differently. So there is no single answer.


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## tomo pauk (Nov 24, 2018)

Greg Boeser said:


> OK, but only the B-26 MA (201 made), the B-26A (139 made) and the first 80 or so B-26Bs used the lower rated engine. All B-26Bs, Cs, Fs & Gs used in NA and Europe used the more powerful, and thirstier, R-2800-41(B-26B and B-2) and R-2800-43 (B-26B-3 and later).
> By the way, I have copies of several B-26 manuals and each presents the fuel consumption numbers differently. So there is no single answer.



There might not be a single answer, but per each HP made, the R-2800 was not a fuel junky when compared with R-2600. Eg. the R-2800-43 was to use less than 100 USG per engine at 15000 ft, 2200 rp, full throttle, auto-lean.
The highest actual figure for the -43 I was able to find is 199 gph, per engine, for 2400 rpm operation (max continuous setting, max 1550 HP, low gear); the R-2600-13 making 1500 HP max at 2400 rpm, low gear, again max cont setting, 180 gph. Both engines using rich mixture here.


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## MIflyer (Nov 24, 2018)

The prototype B-25H used R-2800's instead of R-2600's. They gave up on the idea when they pulled the wings off doing a high speed run over Mines Field.


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## Zipper730 (Nov 25, 2018)

tomo pauk said:


> Intercooler was present there from day one.


I know most all twin-stage superchargers had them, but the B-26 with a single-stage twin-speed supercharger would not have one. If it were switched to twin-stage, it would then require them.

It was kind of a hypothetical...




Shortround6 said:


> A text book from 1942/43 claimed that an estimated 10 cubic feet of space was needed for an intercooler installation for a 1000 HP engine. Due to economy of scale you don't need 20 cubic feet for a 2000 HP engine but you do need a lot more than ten.


How much would you need, if you were to make a guesstimate?

Do you think one could have designed enough room to fit an intercooler inside the engine nacelle, the wing, or both?


> Adding 2 stage supercharger to an airplane will improve it's performance above 15,000 ft or so but hurt it under that height


The horsepower differences in the F4U seem to cover things at lower altitudes


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## tomo pauk (Nov 25, 2018)

Zipper730 said:


> I know most all twin-stage superchargers had them, but the B-26 with a single-stage twin-speed supercharger would not have one. If it were switched to twin-stage, it would then require them.
> 
> It was kind of a hypothetical...
> How much would you need, if you were to make a guesstimate?
> ...



The intercooler can be also fitted in front of the leading edge of the wing. I am of opinion that a) it would've been possible to outfit the B-26 with a 2-stage R-2800 and b) that it would've improved performance above 7-8 thousand feet.
But then, deficiences of the B-26s were not in it's powerplant, but rather in it's fuselage (designed around big crew compartments rather than around bomb bay and fuel tanks, and not a single galon of fuel) and wing (no advantage taken from latest airfoil knowledge, nothing new either in high lift devices installed, earswhile too small a wing).



Shortround6 said:


> A text book from 1942/43 claimed that an estimated 10 cubic feet of space was needed for an intercooler installation for a 1000 HP engine. Due to economy of scale you don't need 20 cubic feet for a 2000 HP engine but you do need a lot more than ten. This makes it rather difficult to add 2nd stages and intercooler to existing designs.
> Please look at the B-24 for an extreme example. Originally designed and built without the turbo with a round cowling, when the turbo was added the cowling was changed to the oval shape with large scoops/intakes on both sides. One side is the combined intake air and oil cooler. The other side is entirely cooling air for the air cooler.
> Adding 2 stage supercharger to an airplane will improve it's performance above 15,000 ft or so but hurt it under that height, unless your fuel/engine will allow for lots over boost.
> Most radials were severe duty engines for fuel and did not tolerate over boost well without water injection.



The difference in power, 1-stage vs. 2-stage B series R-2800 at 8500 ft was 200 HP, mil power, and 150 HP for max continous power. So I don't think that we'd see any drop of performance in any altitude.
BTW - I don't think that 2-stage R-2800 needed even 15 cu ft of space (nor that a 2-stage V-1650 needed even 10 cu ft), and even so it is easy to find that space on a bomber, let alone outside of a bomber.


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## Greg Boeser (Nov 25, 2018)

tomo pauk said:


> But then, deficiences of the B-26s were not in it's powerplant, but rather in it's fuselage (designed around big crew compartments rather than around bomb bay and fuel tanks, and not a single galon of fuel) and wing (no advantage taken from latest airfoil knowledge, nothing new either in high lift devices installed, earswhile too small a wing).
> 
> 
> > The fuselage and wing were designed based on a low drag NACA symmetrical airfoil. The lowest drag possible was sought in order to meet the speed requirement of the proposal. The fuselage was sized to accommodate side by side pilots and a bomb bay of roughly the same dimensions as the bomb bay of the early B-17. It also included a second, smaller, bomb bay to meet the bomb carrying requirements of the specification. In effect, the B-26 was a downsized heavy bomber, while the B-25 was an upsized attack bomber (based as it was on NAA's NA 40 design.) The Martin design team created an aircraft that best fit the specifications, but at the expense of a very high, for its day, stall speed.


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## MIflyer (Nov 25, 2018)

An RAF crewman that transitioned from Venturas to B-25's said that when they got the Mitchells they had an airplane that was better in every respect.


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## wuzak (Nov 25, 2018)

Maxwell Sparks, who flew on the Operation Jericho raid, said that changing from the Boston to the Mosquito was like going from Del Boy's 3 wheeler to a Ferrari (or something similar),

Not quite sure what Bostons or Venturas have to do with the topic of B-25 vs B-26.


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## Zipper730 (Nov 25, 2018)

tomo pauk said:


> The intercooler can be also fitted in front of the leading edge of the wing.


So it would be put on the wings leading edge or on the engine nacelle?


> I am of opinion that a) it would've been possible to outfit the B-26 with a 2-stage R-2800


I'm surprised that they didn't agree for a single-staged blower for the time being with the intent to go to a twin-speed blower when the time came. It might sound silly, but it would have left the aircraft with considerable growth potential.


> it would've improved performance above 7-8 thousand feet


How much would you suggest it would have increased the short and long-winged variants in terms of cruise and top-speed?


> But then, deficiences of the B-26s were not in it's powerplant, but rather in it's fuselage (designed around big crew compartments rather than around bomb bay and fuel tanks


Why did they build it that way?

As for the wings: Why was their aerodynamic knowledge fairly primitive? As for lift-devices, the aircraft had flaps...


> The difference in power, 1-stage vs. 2-stage B series R-2800 at 8500 ft was 200 HP, mil power, and 150 HP for max continous power. So I don't think that we'd see any drop of performance in any altitude.


Yeah, it would be faster all around. At higher altitudes, with the speed increasing, you have to consider exhaust thrust too.


> I don't think that 2-stage R-2800 needed even 15 cu ft of space


Fascinating...



MIflyer said:


> An RAF crewman that transitioned from Venturas to B-25's said that when they got the Mitchells they had an airplane that was better in every respect.


That does raise an interesting question: You think the war would have really worked out much different if the B-26 wasn't built at all, or built and then cancelled after it's low speed problems were brought up?


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## Jugman (Nov 26, 2018)

swampyankee said:


> On the other hand, the B-24 has better payload-range characteristics than the B-17, so it had uses, such as maritime patrol, that the B-17 could not do as well.
> 
> The B-26 had worse payload-range than the B-25, so there would seem very little advantage to the B-26.



Actually It's the opposite, the B-17 had the superior range/payload characteristics. Early B-24s had ~15% greater useful load available for fuel and bombs and a somewhat greater installed fuel capacity over contemporary B-17s. This allowed the B-24 trade off more bombs for fuel and this gave the B-24 a longer range. When the overload tanks were add to the B-17, it's overall better aerodynamics gave it ~10% greater range.


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## GrauGeist (Nov 26, 2018)

The B-17 was originally designed for attacking ships at sea...this was because the USAAC envisioned that any enemy attacking the U.S. had to come by sea, so the B-17 was designed with that in mind.

So the B-17 had the ability both in range and warload to conduct maritime duties and the USN did in fact, have several B-17s serve in that role as the PB-1.

But the B-17 was in high demand from the USAAF, and the B-17 was only being manufactured at three plants: Boeing Seattle, Douglas Long Beach and Vega Burbank, where the B-24 was being manufactured in larger numbers from more plants: Consolidated San Diego, Consolidated Ft. Worth, Ford Willow Run, North American Dallas and Douglas Tulsa.


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## tomo pauk (Nov 26, 2018)

Greg Boeser said:


> The fuselage and wing were designed based on a low drag NACA symmetrical airfoil. The lowest drag possible was sought in order to meet the speed requirement of the proposal. The fuselage was sized to accommodate side by side pilots and a bomb bay of roughly the same dimensions as the bomb bay of the early B-17. It also included a second, smaller, bomb bay to meet the bomb carrying requirements of the specification. In effect, the B-26 was a downsized heavy bomber, while the B-25 was an upsized attack bomber (based as it was on NAA's NA 40 design.) The Martin design team created an aircraft that best fit the specifications, but at the expense of a very high, for its day, stall speed.



Fuselage also included an extra crew compartment for two men seating side a side, with passage between them, the compartment being located between pilots' compartment and bomb bay. All said, there was plenty of space for 8 (9?) crew members - 5 in front of bomb bay, 3 (4?) aft. Indeed, worthy of a 4-engined heavy bomber. All of the volume alloted for men added weight and drag, despite the neat shaping of fuselage.
Bomb bay might be big per US standards, but not per RAF standards.
As for the wing, we have several things that matter when bombers are in question:
- how good is the symetrical air foil when it is about weight lifting?
- wing loading
- lack of Fowler flaps (or the like) - people at Martin knew well that those work, yet none was incorporated
- relatively thin wings (15%?) do work



Zipper730 said:


> So it would be put on the wings leading edge or on the engine nacelle?
> I'm surprised that they didn't agree for a single-staged blower for the time being with the intent to go to a twin-speed blower when the time came. It might sound silly, but it would have left the aircraft with considerable growth potential.
> How much would you suggest it would have increased the short and long-winged variants in terms of cruise and top-speed?
> Why did they build it that way?
> ...



Perhaps I went too far claiming that people at Martin were not using the most recent knowledge of airfoils. However, there wing airfoil choosen does not show any low drag vs. lift properties that one will need for a fast and heavy A/C. Flaps were 'simple', not Fowler or a variant, that both increase wing area and camber of the wing.
I'd put the intercoolers in front of leading edge of the wing.
Don't mix supercharger stages with speeds - 2-speed S/C was always on R-2800s of the B-26s, 2-stage was never. The greatest improvement in speed would've came at high altitudes, say above 20000 ft, probably comfortably above 350 mph.
Why did the built it that way? We need to ask Magruder.


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## swampyankee (Nov 26, 2018)

GrauGeist said:


> The B-17 was originally designed for attacking ships at sea...this was because the USAAC envisioned that any enemy attacking the U.S. had to come by sea, so the B-17 was designed with that in mind.
> 
> So the B-17 had the ability both in range and warload to conduct maritime duties and the USN did in fact, have several B-17s serve in that role as the PB-1.
> 
> But the B-17 was in high demand from the USAAF, and the B-17 was only being manufactured at three plants: Boeing Seattle, Douglas Long Beach and Vega Burbank, where the B-24 was being manufactured in larger numbers from more plants: Consolidated San Diego, Consolidated Ft. Worth, Ford Willow Run, North American Dallas and Douglas Tulsa.



The sources I have seen have the B-24 being faster and having longer range than the B-17 with the same payload. See, for example, B17 vs B24, and B-17 vs. B-24 | The Veterans Breakfast Club | Creating communities of listening

This doesn’t necessarily mean it was a better combat aircraft, at the B-17 was reputedly both less difficult to fly and more robust.


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## MIflyer (Nov 26, 2018)

I have not heard it explained why the 26 beat the 25 to the Pacific but then was replaced by the 25 there and was relegated to a bit in the Med and the ET where the 25 also served. The 25 also served in the Med and ETO. I know of no mi than the 25,ssion where the 26 proved to be better tihan the 25, but clearly there were those that the 25 was superior, including as a trainer. Some B-26 units were transitioned to the A-26 in the ETO.

And the Ventura and PV-1 are much more like the B-26 than the B-25.


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## wuzak (Nov 26, 2018)

tomo pauk said:


> Why did the built it that way? We need to ask Magruder.



It may be the operational requirements from the USAAC/F.

The term "medium bomber" seems to have meant a bomber that operates at medium altitudes, not a bomber with a mid-range bomb load. That would mean that turbos or 2 speed superchargers were not required.

btw there was a proposed version of the B-26 with V-3420s. That would have been interesting to see.


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## tomo pauk (Nov 26, 2018)

wuzak said:


> It may be the operational requirements from the USAAC/F.
> 
> The term "medium bomber" seems to have meant a bomber that operates at medium altitudes, not a bomber with a mid-range bomb load. That would mean that turbos or 2 speed superchargers were not required.



Martin (company) came out with plenty different engine set-ups for their Model 179, some including two-stage supercharged R-2600 or R-2800, and some inculding turboed R-2600, R-2800 and even R-3350. The company probably wouldn't tried to stretch themselves to offer what is not needed by requirement? So IMO the term 'medium bomber' stipulated what is a 'classic' medium bomber as we know it: a 2-engined bomber, with no regard to the best altitude.



> btw there was a proposed version of the B-26 with V-3420s. That would have been interesting to see.



Yes, it is featured in the 'Vee's for victory' book - probably proposal by Allison?


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## Zipper730 (Nov 26, 2018)

tomo pauk said:


> Fuselage also included an extra crew compartment for two men seating side a side, with passage between them, the compartment being located between pilots' compartment and bomb bay.


I'm curious as to why that would be a requirement? I could understand the idea of carrying people in the bomb-bay -- the British had that in several bombers as a way of carrying troops (it would also carry more than just 2 guys)

It's weird that they had the same bay configuration that the B-17 and B-24 had (cat-walk) instead of just a cavernous structure (the B-25 had such a configuration): I'm curious if the bomb-bay would have more volume if the bay had a flat ceiling as a load-bearing structure instead of the catwalk.


> As for the wing, we have several things that matter when bombers are in question



I never knew they used a symmetrical airfoil, the only conceivable benefits I could find with such an airfoil
Flying inverted: Not really applicable as the design had a Norden bomb-sight which would suffer a gyro-precession as little as 18-degrees of bank
Dive-Bombing: I don't recall the aircraft ever built for this purpose

I figure the decision to keep the wing-span/area small was to decrease drag for high-speed. It certainly had low-speed penalties
The lack of Fowler-flaps is a surprise, as it would have greatly increased the ability of the aircraft to fly at low-speed. The only thing I could think of would be that it might weigh more than the plain-flap.
The wings were 15% thickness to chord?
The aircraft's fuselage did have very nice, clean lines -- very good attention to detail it seemed. I was genuinely surprised about the wings.


> However, there wing airfoil choosen does not show any low drag vs. lift properties that one will need for a fast and heavy A/C.


How would it compare with the B-25?


> I'd put the intercoolers in front of leading edge of the wing.


As long as it fits, and bonus points if it get good ram, lol


> Don't mix supercharger stages with speeds - 2-speed S/C was always on R-2800s of the B-26s, 2-stage was never.


Sorry about that


> The greatest improvement in speed would've came at high altitudes, say above 20000 ft, probably comfortably above 350 mph


Wow that's fast...


> Martin (company) came out with plenty different engine set-ups for their Model 179, some inculding two-stage supercharged R-2600 or R-2800, and some including turboed R-2600, R-2800 and even R-3350.


I was under the impression that they didn't want the twin-stage supercharger because it wasn't available in quantity in 1940. I'm curious if the turbocharged R-2800 was available any quicker?



wuzak said:


> It may be the operational requirements from the USAAC/F


What were the specifications that gave birth to the aircraft?


> The term "medium bomber" seems to have meant a bomber that operates at medium altitudes


Are you serious? Last I checked, a medium-bomber was generally an aircraft with a medium-ranged bomb-load that could be carried over a medium-distance.


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## MIflyer (Nov 26, 2018)

With the B-26, in order to get to the nose compartment the coplilot had to move his seat back out of the way. There were no seats in the nose compartment, although the bombardier rode there. The navigator had his desk aft of the pilot's seat, but after takeoff he went down to the nose so he could argue with the bombardier over where they were. The nose compartment offered a much better view than did the navigator's compartment. 

As to why the B-25 used a bomb/nav and the B-26 had two separate crewmen for those tasks, I have no idea. I guess that is a vote toward the "smaller 4 engined bomber" idea.

In order to use the nose gun the Norden bombsight had to be removed. I do not think this was the case for the B-25.

And, finally, the B-25 was better because one of my high school teachers was bomb/nav on them, starting his combat career aboard Plane No. 10 from the USS Hornet.

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## tomo pauk (Nov 26, 2018)

Zipper730 said:


> I never knew they used a symmetrical airfoil, the only conceivable benefits I could find with such an airfoil
> Flying inverted: Not really applicable as the design had a Norden bomb-sight which would suffer a gyro-precession as little as 18-degrees of bank
> Dive-Bombing: I don't recall the aircraft ever built for this purpose
> 
> ...



On B-26, 17% TtC at root, same for B-25, that used the 5-digit NACA 230 series. 
Turbo + R-2800 was also not a done deal in 1940.


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## Zipper730 (Nov 26, 2018)

MIflyer said:


> With the B-26, in order to get to the nose compartment the coplilot had to move his seat back out of the way. There were no seats in the nose compartment, although the bombardier rode there. The navigator had his desk aft of the pilot's seat, but after takeoff he went down to the nose so he could argue with the bombardier over where they were. The nose compartment offered a much better view than did the navigator's compartment.


Why would you not have any seats in the nose where the bombardier would sit?


> In order to use the nose gun the Norden bombsight had to be removed.


Now that is a major problem...



tomo pauk said:


> On B-26, 17% TtC at root, same for B-25, that used the 5-digit NACA 230 series.


What was the typical figures for the A-20 and B-25?


> Turbo + R-2800 was also not a done deal in 1940.


The twin-staged R-2800, however was available in small numbers, which makes it more of a sure thing...


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## Airframes (Nov 26, 2018)

The British had a way of carrying several troops in the bomb bays of (British) bombers ???
The only British bomber I know of that could do this, or did do this, was the Mosquito, which, on the 'ball bearing run' from Sweden to Scotland, could carry *one* person, on a hammock-like arrangement, in the bomb bay - very cold and uncomfortable.


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## GregP (Nov 26, 2018)

A medium bomber was supposed to operate with a "medium" bomb load over a "medium" range. Most could handle a heavy bomb load over a short range, but were seldom required to do so.

A heavy bomber was supposed to carry a heavy bomb load over a long range, or a medium bomb over a very long range. Naturally, they could carry very heavy bomb loads over short ranges but, again, were seldom required to do so.

This is, of course, US terminology. I am not sure exactly what the British meant by medium and heavy bomber. The Lancaster could carry 7000 pounds of bombs for 2,530 miles; 12000 pounds for 1,730 miles; or 22,000 for 1,550 miles.

The B-29 "Super-Heavyweight" bomber could carry 20,000 pounds for 3,250 miles or quite a bit more for shorter distances. It could carry two 22000 pound "Grand Slams" at the same time, externally, but was not required to do so in the ETO, and the PTO didn't have many targets at a short enough range for it to ever fly that mission in the Pacific in combat.


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## wuzak (Nov 26, 2018)

In British terminology, the Manchester and Halifax were built to a specification for a medium bomber.


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## wuzak (Nov 26, 2018)

Zipper730 said:


> The twin-staged R-2800, however was available in small numbers, which makes it more of a sure thing...



Small numbers doesn't make it more of a sure thing, especially as they were most likely earmarked for the F4U.


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## Greg Boeser (Nov 26, 2018)

The why didn't they use fowler flaps, different wing etc. on B-26 is simple. The Martin Co. asked what the overriding requirements for the contract were and was told: speed, bombload, structural strength. Low speed handling was not addressed, so they ignored it. Magruder was hoping for more powerful engines, but didn't get them. Even he regretted not insisting on the longer wing once the single stage R-2800 was selected. Martin won the competition hands down, and North American only got a consolation contract because Martin couldn't commit to filling the full quota of airframes the army was after.


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## Greg Boeser (Nov 26, 2018)

MIflyer said:


> With the B-26, in order to get to the nose compartment the coplilot had to move his seat back out of the way. There were no seats in the nose compartment, although the bombardier rode there. The navigator had his desk aft of the pilot's seat, but after takeoff he went down to the nose so he could argue with the bombardier over where they were. The nose compartment offered a much better view than did the navigator's compartment.
> 
> As to why the B-25 used a bomb/nav and the B-26 had two separate crewmen for those tasks, I have no idea. I guess that is a vote toward the "smaller 4 engined bomber" idea.
> 
> ...


The bombardier sat on the spare ammo canister. The bombsight swung out of the way. Navigators often hung out behind the pilots watching over their shoulders. 
Initially, both the B-26 and B-25 had bombardiers and navigators. The bombardier was often an enlisted man. As the war progressed and individual aiming gave way to formation bombing the bombardier and navigator duties were usually carried out by a single individual (togglier). Only lead planes carried a lead bombardier and lead navigator, generally the most skilled in the unit.
An attempt was made with the B-26C-6 to eliminate the co-pilot, but these were converted back to standard configuration in the field.

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## Greg Boeser (Nov 26, 2018)

MIflyer said:


> I have not heard it explained why the 26 beat the 25 to the Pacific but then was replaced by the 25 there and was relegated to a bit in the Med and the ET where the 25 also served. The 25 also served in the Med and ETO. I know of no mi than the 25,ssion where the 26 proved to be better tihan the 25, but clearly there were those that the 25 was superior, including as a trainer. Some B-26 units were transitioned to the A-26 in the ETO.
> 
> And the Ventura and PV-1 are much more like the B-26 than the B-25.


The B-26 beat the B-25 to the Pacific because the 22nd BG had a full complement of B-26s and was considered fully operational when the war broke out. Technically, the B-25 did beat the B-26 to Australia, several had been ferried to the Dutch, but the loss of the NEI meant they were stuck in Australia while the crews trained up on them. Many of these were then traded back to the USAAF to equip two squadrons of the 3rd BG (Light). B-26s were deployed to Alaska in January 1942. B-26 production actually was ahead of B-25 production at this time because the Martin did not make any major changes to the initial production batch of B-26 MAs, whereas North American changed the B-25 several times before the introduction of the B-25C, the first combat capable model, was introduced. 
By the way, both the B-26 and B-25 got their baptism of fire on the same day, 6 April, 1942, the B-26s bombing Rabaul with the aid of a 250 gallon bomb bay tank (in the left side of the forward bay), while the shorter legged B-25s hit Gasmata on the south west coast of New Britain. 
B-26 strength in the Pacific peaked in mid to late 1942, with eight squadrons (two in Alaska, two in the South Pacific (with B-26Bs) and a full group of four squadrons in Australia.
B-25 strength in the Pacific went from two squadrons in April '42 to four in August, but really didn't hit it's stride until mid -'43 when the 38th BG was brought up to full strength, the 42nd BG (which had absorbed the two SOPAC B-26 squadrons) converted fully to B-25s, the Alaska based squadrons converted to B-25s, and three of the four squadrons of the 22nd BG converted briefly to B-25s, before the entire group was converted to a heavy BG with B-24s starting in January '44. The last B-26 squadron's last mission was 9 Jan 1944. Coincidently, it was the squadron that had flown the first B-26 mission in April 1942

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## Zipper730 (Nov 27, 2018)

wuzak said:


> Small numbers doesn't make it more of a sure thing


True enough, but I'm still surprised they didn't see high-altitude capability as being more useful. What road-blocks affected twin-stage supercharger set-ups in the United States? I know as a general rule the USAAC favored turbochargers almost without fail, but I'm curious if it would have hurt them to have given twin-stage supercharging a whack before the Merlin...



Greg Boeser said:


> The why didn't they use fowler flaps, different wing etc. on B-26 is simple. The Martin Co. asked what the overriding requirements for the contract were and was told: speed, bombload, structural strength. Low speed handling was not addressed, so they ignored it.


Structural strength means like g-load?


> The bombardier sat on the spare ammo canister. The bombsight swung out of the way.


So it could be quickly swung back into position and used?


> Initially, both the B-26 and B-25 had bombardiers and navigators. The bombardier was often an enlisted man. As the war progressed and individual aiming gave way to formation bombing the bombardier and navigator duties were usually carried out by a single individual (togglier). Only lead planes carried a lead bombardier and lead navigator, generally the most skilled in the unit.


I thought somebody stated that the B-25's switched to the bombardier/navigator system


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## Ascent (Nov 27, 2018)

Airframes said:


> The British had a way of carrying several troops in the bomb bays of (British) bombers ???
> The only British bomber I know of that could do this, or did do this, was the Mosquito, which, on the 'ball bearing run' from Sweden to Scotland, could carry *one* person, on a hammock-like arrangement, in the bomb bay - very cold and uncomfortable.


Wasn't it a requirement of bombers designed pre war and early war to be able to carry troops as a secondary requirement?

And I'm sure I've read that the Halifax was used to carry para's. Or possibly I'm thinking of their use as glider tugs.


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## MIflyer (Nov 27, 2018)

In the book I read, the only time they used the nose gun the bomb took it off and handed it to the nav, who, having no place to sit, squatted there and held it while the bomb blazed away.

The XB-28 was a high altitude medium. They built one and cancelled it. By late in WWII they realized that the main value of mediums was in low altitude attacks.


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## Airframes (Nov 27, 2018)

Ascent, pre-war types such as the Bombay were, to an extent, dual purpose.
The Halifax, Stirling and Whitley were used for para dropping, but the troops were in the fuselage, not the bomb bays, and dropped through a 'hole' in the floor.


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## Zipper730 (Nov 27, 2018)

Greg Boeser said:


> An attempt was made with the B-26C-6 to eliminate the co-pilot, but these were converted back to standard configuration in the field.


Seems they were going for the RAF idea...



Ascent said:


> Wasn't it a requirement of bombers designed pre war and early war to be able to carry troops as a secondary requirement?


The RAF did seem to have this as a requirement on at least some of the bomber specifications



MIflyer said:


> In the book I read, the only time they used the nose gun the bomb took it off and handed it to the nav, who, having no place to sit, squatted there and held it while the bomb blazed away.


Seems like a useless arrangement


> The XB-28 was a high altitude medium. They built one and cancelled it. By late in WWII they realized that the main value of mediums was in low altitude attacks.


I was under the impression (and I could be wrong) that as originally intended, attack aircraft were tactical bombers, and bombers were strategic bombers. For some particular reason I'm not entirely sure of, the B-25 and B-26 were classified as bombers.


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## Greg Boeser (Nov 27, 2018)

Pre-war USAAF doctrine envisioned three classes of aircraft. Attack aircraft used in direct support of the ground troops classed A- for attack, heavy bombers for attacking strategic targets, and medium bombers for those "in between" targets. By the latter part of the war, with the introduction of the B-29 and the A-26, the medium bomber concept had fallen out of favor. The A-26 could carry as many as, or more bombs than, the B-25 and B-26, and the Army was seriously considering reclassifying the B-17 and B-24 as "medium".


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## GregP (Nov 27, 2018)

From Table 7 in Ray Wagner’s American Combat Planes in ETO:

1. B-25: 63,177 sorties, 84,980 tons bombs, 380 combat losses, 193 Enemy A/C Claimed.

2. B-26: 129,943 sorties, 169,382 tons bombs, 911 combat losses, 402 Enemy A/C Claimed.

The B-25 and B-26 both have almost exactly the same tons per sortie (1.345 and 1.304), losses per 1000 sorties (6 and 7), and enemy aircraft claimed per 1000 sorties (3.06 and 3.09). The Marauder flew twice the sorties of the B-25 and performed almost exactly the same in these categories.

From 1941 to 1945, the B-25 had 921 accidents with 233 fatal. The B-26 had 739 accidents with 223 fatal. From Statistical Digest of WWII. So, the B-26 has a slightly higher fatal accident rate. 446 B-25s wrecked. 408 B-26s wrecked. To all intents and purposes, they look almost identical statistically. The B-26 was faster, but not by a lot. It had a high accident rate at first that was cured very effectively by training. Unless you are flying from a short strip, I see little to chose between them.

In person, the B-25 flies VERY well. I have no experience at all with the B-26 other than seeing Kermit's plane, and have never seen their flying characteristics compared. I lean toward the R-2800 but also lean toward the B-25 if only from familiarity. The one we have (Planes of Fame) has been very reliable (it just got back from an uneventful trip to Italy ... except for the bill for petrol), especially considering that WWII ended 73 years ago. Our 75+ year old R-2600 engines run GREAT and so do our R-2800s.

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## Zipper730 (Nov 27, 2018)

Greg Boeser said:


> Pre-war USAAF doctrine envisioned three classes of aircraft. Attack aircraft used in direct support of the ground troops classed A- for attack, heavy bombers for attacking strategic targets, and medium bombers for those "in between" targets.


I didn't know that, I figured light-bomber was for the in-between part since the attack category would have taken up some of the light-bomber category too.


> The A-26 could carry as many as, or more bombs than, the B-25 and B-26, and the Army was seriously considering reclassifying the B-17 and B-24 as "medium".


Yeah and the development of the B-47 would put an aircraft in the same size range as the B-29 as a medium bomber. The B-29's and B-50's would eventually be reclassified as mediums from Very Heavy at some point in time.




GregP said:


> From Table 7 in Ray Wagner’s American Combat Planes in ETO:
> 
> 1. B-25: 63,177 sorties, 84,980 tons bombs, 380 combat losses, 193 Enemy A/C Claimed.
> 
> ...


Yeah, honestly -- there's a part of me that wonders if there'd have been any difference if we basically built another 4000-5000 and either scrapped the B-26 or stopped the production line early.


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## Jugman (Nov 28, 2018)

swampyankee said:


> The sources I have seen have the B-24 being faster and having longer range than the B-17 with the same payload. See, for example, B17 vs B24, and B-17 vs. B-24 | The Veterans Breakfast Club | Creating communities of listening
> 
> This doesn’t necessarily mean it was a better combat aircraft, at the B-17 was reputedly both less difficult to fly and more robust.



Context! Context! Context! It's all about context. At most altitudes the B-17 had greater range than the B-24 because its engines had somewhat better fuel consumption. Appendix 2 of this range comparison illustrates this quite nicely. At higher weights the B-17 did not have enough power above 20,000ft to maintain an optimal cruise profile.

Purely from a range and endurance stand point the B-17 would have been the better patrol aircraft.

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## Greg Boeser (Nov 28, 2018)

But the extra bomb bay of the B-24 meant it could carry auxiliary tanks while still carrying a decent payload.


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## Jugman (Nov 29, 2018)

Greg Boeser said:


> But the extra bomb bay of the B-24 meant it could carry auxiliary tanks while still carrying a decent payload.



The bomb bays for both aircraft had the same bomb capacity and their bomb bay tanks cut it in half. In any event the addition of extra wing tanks in both aircraft made bomb bay tanks unnecessary.


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## GrauGeist (Nov 29, 2018)

The B-17 and B-24 also used "Tokyo Tanks", which were removable tanks fitted into the wings, outboard of the engines.
The cells were self-sealing and connected to the fuel system via valving. The drawbacks to these tanks were that it required removing wing panels to install/remove, which was labor intensive. Also, they had no fuel gauge.

Here's a diagram of the B-17F's complete fuel storage (the B-17G was identical). 
It also includes both the Tokyo Tank arrangement (find tanks numbered 1 through 9, port & starboard) and the bomb-bay tanks.

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## Zipper730 (Nov 29, 2018)

Greg Boeser said:


> But the extra bomb bay of the B-24 meant it could carry auxiliary tanks while still carrying a decent payload.


But it would have been way better with one huge bomb-bay: Why use two bomb-bays when one HUGE bay will work?


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## Reluctant Poster (Nov 29, 2018)

The FEAF did not want the A-26, preferring to keep the B-25. The attached memo discusses the battle over plans to convert all medium bomber units to the A-26. Note that the A-20 and the B-26 went out of production well before the war ended.


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## GreenKnight121 (Nov 29, 2018)

Micdrow said:


> I assume you are talking about the Doolittle raid but the Navy later on did more experiments with the B-25 or known to the navy as the PBJ. As you can see by the pictures below from the book Squadron Signal B-25 in action book.
> 
> View attachment 352612





Balljoint said:


> Doolittle would have appreciated that option.



What Dolittle would really have loved was the other half of that test aboard Shangri-La.

The PBJ-1H was also equipped with catapult bridle hooks - and made a catapulted launch as well.

http://steeljawscribe.com/2007/10/05/flightdeck-friday-more-oddities


> Lieutenant Commander Syd Bottomley, who had earlier served as XO of VB-3 at the Battle of Midway and then succeeded Max Leslie as squadron CO when Leslie fleeted up to CAG-3, was assigned to the Ship Experimental Unit of the Naval Aircraft Factory at Mustin Field, Philadelphia in the fall of 1943.
> 
> To further prove their points of hook location and swivel, Bottomley sought and received permission for BuAer to include their PBJ-1H in catapult and shipboard handling tests. An SBD tail hook assembly (the SBD was considered to have the most reliable tailhook arrangement) was installed on the PBJ and it was readied for further testing. In land based tests conducted at USCGAS Cape May an unexpected problem appeared: with full-flight engagement of the arresting gear, the single pilot’s seat lock would disengage and let the pilot and seat slide forward onto the yoke. This was a big surprise the first time it happened and certainly not a happy event for Bottomley. As a solution, a steel strap was welded to the top of the seat from the bulkhead behind the pilot to keep the seat in place.
> 
> ...

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## Reluctant Poster (Nov 29, 2018)

This memo discusses the efficiency of various USAAF bombers in the Pacific. As you might expect the B-29 wins hands down with the A-26 a distant second.

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## Shortround6 (Nov 29, 2018)

Part of the Reason the B-26 was built the way it was and used the engines it did was timing. 
It was only about 1-2 months behind the B-25 and over 500 had been built before the 5th F4U was built and 1000 had been built before the first F6F. 
The two stage engines simply were not available (as a production item) when the plane was designed and built. 
Adding the two stage engines at a later date is a lot harder than it appears. 




or google any cut away of a B-26. The wing spars (two) are very near the front of the wing and near the back (which complicates adding Fowler flaps at a later date)
The wing root is full of fuel tank/s between the spars and the outer wing panels contain fuel tanks from the nacelle outwards.
The wing leading edge is full of control runs (cable or pushrod?) .

The P-61 used two stage engines with all intakes in the wing leading edge but the P-61 actually used a bigger wing than the B-26 (even the later ones) and had the spars further in from the leading and trailing edges, it also held less fuel than a B-26 wing. 

Please take a good look at a P-61C or F-15 which used turbo R-2800s and see the extra lump under each engine nacelle and the two added scoops at the 5 and 7 o'clock positions on the cowl. You may not be able to swap a turbo for a two stage supercharger without additional intercooling or plain cooling airflow. 

Had they been willing to delay manufacture of the B-26 then the more advanced engines might have been used. But it would have required quite a few changes to the original B-26 structure. 

AS for size/drag. please note that on the F6F cowl and the three scoops at the bottom the outer two ONLY feed the intercoolers. the center one takes care of both the oil cooler and the combustion intake air. You need between 2 and 3 times the air flow of combustion air for the intercoolers to work properly. Late B-26 air intakes are over sized to allow for easy fit of air filters for dusty conditions so don't use them for comparison

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## rsgwynn1 (Nov 17, 2019)

The proposed B-27 Macgyver never got off the ground, but it solved the difference problem by welding the front half of a B-25 to the rear half of a B-27. It was held together by duct tape, rubber bands, office paper, and paper clips and got a huge power assist from two propane-tank-assisted jets on the tail assembly. Luckily the war ended before its designer and his crew could get killed.

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## tomo pauk (Nov 17, 2019)

Now that's what I call contribution.

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## MIflyer (Nov 17, 2019)

Before the end of WWII the USAAF proceeded to phase out all of the twin engined trainers and replace them with B-25's. The TB-25 served as a twin engined trainer and general purpose hack transport with the USAAF and USAF into the late 1950's.

The B-25H originally was supposed to use R-2800 engines but the first prototype of that installation pulled its wings off while doing a high speed pass over Mines Field.

The NAA B-28 used R-2800 engines, was designed for high altitude operations, and looked a lot like the B-26.

The reason the B-26 units in the ETO had such a low loss rate while flying at the 15,000 ft altitude where German flak was so deadly was that the units studied what the RAF had found out and when over enemy territory constantly changed directions every five minutes or so, less time than the Germans required to set up a flak ambush. This may have been a factor in the B-26 having both a Navigator and a Bombardier, while the B-25 had one man do both.

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## Greg Boeser (Nov 17, 2019)

B-26 crews in the ETO generally carried a crew of six. Pilot, co-pilot, bombardier/navigator, engineer, radio operator, gunner. Lead ships for group, squadron, and flight would carry both a dedicated bombardier and navigator, usually the best trained and most experienced in the group. The bombardier/navigators were often referred to as "toggliers" as their job was to toggle off their bombs on cue with the lead ship's drop. One thing that ETO based B-26 units did was train to fly in very tight formation, presenting a smaller target for flak, which coupled with frequent jinking while in enemy airspace, made them very difficult to hit. There were instances in which a lead plane in a box of six might be hit and catch fire, engulfing the slot plane behind it in flsmes.


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## MIflyer (Nov 17, 2019)

The book I read by a B-26 navigator said that they had both a bombardier and a navigator. The bombardier was also trained as a navigator, so after takeopff the co-pilot would silde back his seat and let the Nav go into the nose, where he and the bombardier would crouch (there being no seats in the nose) and argue about where they were for the whole mission. Also, the nose bubble gun could not be fired without removing the Nordon bomb sight, and on the only occasion in which they were ordered to strafe the target after bombing it, the bombardier pulled the Nordon loose and handed it to the Navigator to hold as he grabbed the .50 cal..

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## Greg Boeser (Nov 17, 2019)

Which book was that? I haven't seen that one yet. Always interested in adding to my B-26 library.


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## MIflyer (Nov 18, 2019)

The book is called "Flying the B-26 Marauder Over Europe" by Carl H Moore. It seems to be available on Amazon and ebay. It came out something like 30 yrs ago. Sorry about missipels; Firefox wonlt let me correct anything this morning

I do recall another book that was not about the B-26 but a B-26 pilot described an interesting incident.

The B-26's in the ETO mainly did not use their package guns for anything, since strafing was quite rare. But one day a B-26 was on the outer edge of a formation and a BF-109 made a firing pass. The B-26 pilot dove after the 109, fired the package guns, and blew the fighter out of the air. He them pulled back up into formation and heard "Nice shooting!" over the radio.

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## Greg Boeser (Nov 18, 2019)

Add that to my book want list for Christmas.


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## RagTag (Mar 12, 2020)

I have never heard the story about taking out the 109 with the package guns. Pretty amazing. I’ve always enjoyed the story in “Battle Over Bavaria” where 1st. Lt. Vining flying the 323rd BG B-26 _Ugly Duckling _fired his package guns at an ME-262 that came into his sights, taking prices out of the tail. He started to track the jet to finish the job but decided the better of it and got back into formation. Maybe the B-26 should have been reclassified as a “_heavy fighter”!_

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## Admiral Beez (Mar 16, 2020)

davebender said:


> Which bomber had superior endurance (i.e. could loiter over battlefield)? Another important feature of a medium bomber.


Could the B-26 accomplish the Doolittle Raid?


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## Shortround6 (Mar 16, 2020)

No.


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## pinsog (Mar 16, 2020)

Admiral Beez said:


> Could the B-26 accomplish the Doolittle Raid?


A B26 could never have taken off from a carrier


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## Snautzer01 (Mar 16, 2020)

pinsog said:


> A B26 could never have taken off from a carrier


That is what they said about the b-25 too.


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## fubar57 (Mar 16, 2020)

A B-25 needed 3795ft. to clear 50yds (this site). A B-26 needed 6100ft. Martin B-26G Marauder

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## Admiral Beez (Mar 16, 2020)

fubar57 said:


> A B-25 needed 3795ft. to clear 50yds (this site). A B-26 needed 6100ft. Martin B-26G Marauder


Was there any other US twin bomber capable of the Doolittle Raid? Douglas A-20 Havoc or PBY Catalina?


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## fubar57 (Mar 16, 2020)

Why? They chose the best that was available. Catalina?


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## Shortround6 (Mar 16, 2020)

Fubar, I think we are being trolled. 

If he can't figure out the differences between an A-20 and a Catalina I don't think I can help him.

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## Admiral Beez (Mar 16, 2020)

Shortround6 said:


> No.


They certainly picked the best available aircraft. It’s remarkable that the B-25 could pull it off, given its designers never intended it for such a short takeoff.

On the B-25s, was there any consideration of using Hornet‘s two flight-deck hydraulic catapults, like this later PBJ?

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## GregP (Mar 16, 2020)

Rer post #164. Yes, the B-26 could have taken off from a carrier. But it would have had to be a LONG carrier! Maybe 2,000 feet long!

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## fubar57 (Mar 16, 2020)

You could hollow out that 2000 ft carrier, fill it with water and now be able to launch PBY Catalinas

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## Admiral Beez (Mar 16, 2020)

GregP said:


> Rer post #164. Yes, the B-26 could have taken off from a carrier. But it would have had to be a LONG carrier! Maybe 2,000 feet long!


AIUI, US medium bombers were designed for shorter grass or rough strips as opposed to the long concrete runways for the B-17 and B-24. So what were the designers of the B-26 thinking with their mile long takeoff?


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## FLYBOYJ (Mar 16, 2020)

Admiral Beez said:


> AIUI, US medium bombers were designed for shorter grass or rough strips as opposed to the long concrete runways for the B-17 and B-24. So what were the designers of the B-26 thinking with their mile long takeoff?


 Circular Proposal 39-640 - The designers gave their customer what they were asking for.


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## FLYBOYJ (Mar 16, 2020)

*"Circular Proposal 39-640"*

_"Although opinion in the AAF placed special stress on strategic bombardment as the prime mission of an air force, the dominant view in the War Department General Staff was officially stated as late as October 1938 in these terms: "the Infantry Division continues to be the basic combat element by which battles are won, the necessary enemy field forces destroyed, and captured territory held." It followed that the primary function of Army aviation was the support of groumi forces in battle. And from this emphasis came the influences which gave shape to the A-20, the A-26, and the more famous B-25 and B-26, all of them designed basically for a supporting mission._

_The medium bomber, considered to be a "pure bombardment type," was intended to operate at medium altitudes of 8,000 to 14,000 feet and primarily against depots, fortified positions, railroad yards, and other such targets along or behind the battle line. Carrying a heavier bomb load and enjoying the advantage of greater range, the mediums could supplement the work of light bombers and might assist the long-range heavy bombers against the nearer targets in a strategic bombardment effort._

_In March 1939, the Army Air Corps issued Circular Proposal 39-640 seeking a twin-engine medium bomber. Also in March of 1939, the month that saw the release of Circular Proposal 39-640, the GHQ Air Force became under control of the Chief of the Air Corps rather than the Army Chief of Staff.28 The Air Corps had achieved greater levels of autonomy yet sought complete independence._

_*The proposal’s specific requirements included a maximum speed greater than 300 miles per hour (mph) with 350 mph desired, a bomb load of 3,000 pounds, range over 2000 miles, a service ceiling of at least 20,000 feet, and defensive armament of at least four .30 caliber machine guns. With particular emphasis on speed, the proposal envisioned a bomber that could fly nearly as fast as contemporary fighter aircraft, but with a bomb capacity that rivaled existing heavy bombers. The aircraft’s range, however, would be significantly less than that of long-range heavy bombers.*_

_The Glenn L. Martin Company’s proposal, later named the B-26 Marauder, earned first place in the resulting competition. The Air Corps ordered both the B-26 and the second place competitor, which became the North American B-25 Mitchell, into production that September. Although the initial contract purchased only 201 Marauders and 184 Mitchells, medium bombers later accounted for a significant portion of the American air inventory. In total, the United States accepted 5,157 Marauders and 9,816 Mitchells with peak inventories of 1,931 and 2,656 of each aircraft respectively._

_The B-26 and B-25 became the primary American medium bombers of WWII. The underlying need for these aircraft, in fact, stemmed from the growing security challenge across the Atlantic Ocean._

_The call for a new medium bomber was an early part of the American rearmament program in direct response to German aggression in Europe. Germany’s annexation of much of Czechoslovakia in 1938, along with troubling reports from America’s ambassador to Berlin, convinced President Franklin Roosevelt that war in Europe was inevitable. He concluded America needed to arm quickly and airpower would play a leading role in defense against Germany. In a White House meeting on 14 November 1938, Roosevelt directed a massive expansion of airpower in which the “Air Corps alone required a strength of 20,000 aircraft backed by an annual productive capacity of 24,000 units.” The 20,000 aircraft target represented a nearly nine-fold increase in the Air Corps’ authorized strength set just two years prior at 2,320 aircraft._

_While Roosevelt placed specific emphasis on the need for long-range aircraft for defense of the entire western hemisphere, the pursuit of medium bombers reflected other environmental and organizational factors. While Germany had invested in medium bombardment, the necessity of this aircraft type was very much up for debate in the United States._

_The concept of medium bombardment remained ill-defined and lacked widespread support. During the inter-war years, bomber classifications changed significantly due to technological advances and changes in doctrine. In the 1920s, the Air Corps classified bombardment aircraft as either light or heavy. Light bombers were primarily single engine models designed to carry fragmentation bombs and small demolition charges while multi-engine heavy bombers would carry much larger bomb loads for greater distances. In 1927, many in the Air Corps sought to develop specialized bombers for day and night operations with day bombers optimized for short-range missions and night bombers flying longer distances into the enemy homeland. The War Department, however, resisted this specialization and insisted on development of all-purpose models._

_In 1930, the Air Corps Tactical School (ACTS) reiterated the need for two types of bombers, yet rather than night or day classification, argued again for light and heavy bomber types based on bomb load capacity. Light and heavy bombers would carry 1,200 or 2,000-pound bomb loads respectively. The term “medium bomber” had yet to make an appearance. The first successful four-engine bomber, however, redefined what the Air Corps saw as a true heavy bomber, essentially creating a middle ground for a medium bomber._

_The Air Board of 1939 offered a limited explanation for the concept of medium bombers. Appointed by the Chief of the Air Corps in March of 1939, the same month of Circular Proposal 39-640, the Air Board classified bombardment aircraft as heavy, medium or light. It defined the medium bomber as “a somewhat lighter, more readily procurable and cheaper airplane designed to meet many of our requirements for bombardment not necessitating the extreme range of our heavy bomber.” By its specifications, medium bombers required the same 2,000-pound minimum bomb load as the heavy bomber but with only half the heavy’s 2,000 miles radius of action._

_Nearly two years after procurement began for America’s WWII medium bombers, the utility of this aircraft type was still largely undefined. Air Corps leaders believed airpower’s greatest utility was its ability to bypass surface forces and conduct strategic bombing of the enemy homeland. Army leadership in the War Department regarded airpower primarily as an auxiliary to ground forces. The War Department favored two-engine bombers and fought the Air Corps’ emphasis on the larger four engine aircraft._

_The desire for rapid expansion and the need to increase industrial production capacity also played a significant role in the competition to build the next medium bomber. These factors influenced the Air Corps’ procurement method, the selection of the B-26 and the decision to build two medium bombers._

_The medium bomber was either a compromise by the Air Corps or an outright victory for War Department leaders. In addition to the aircraft’s desired capabilities, however, production demands also played a significant role. The 1939 Air Board’s description of the medium bomber as a “cheaper and more readily procurable airplane” than its heavy counterpart offers insight into additional reasoning behind the development of medium bombers._

_The competition from Circular Proposal 39-640 introduced a new “abbreviated” procurement method later known as “off the shelf procurement.” Under this method, the Air Corps evaluated aircraft proposals and then initiated full production contracts “off the drawing board.” Under previous methods, manufacturers provided prototypes for in-depth testing before issuance of production contracts. While this method became commonplace to shorten procurement timelines, the B-26 and B-25 were the first aircraft procured without a prototype._

_The Martin Model 179, which later became the B-26, earned first place in the medium bomber competition by a wide margin. Its score of 813.6 points topped North American’s second place NA-62 by 140 points. As the second place design, the North American NA-62, later named the B-25 Mitchell, also earned a production contract. Both planes were twin-engine all-metal midwing monoplanes._

_By 1943 the Army decided to reduce to one medium bomber type in each of the theatres primarily to simplify logistics. While the B-26 had made significant contributions, the B25 offered multiple advantages in the Pacific. First, the Mitchell had proved easier to maintain and had sustained a higher sortie rate than the Marauder. Although the Fifth AF had grown from 404 combat aircraft in September 1942 to 537 in January 1943, only approximately 350 were operational at any given time._

_Having faced continual shortages of both planes and parts, they opted for simpler logistics and a more reliable aircraft. Additionally, the B-25 was better suited for operations from the austere airfields of the Pacific. The Mitchell had a shorter take-off roll and greater propeller to ground clearance making it a better fit for compacted soil and steel mat runways. Because the Mitchell’s initial development proved much less problematic than that of the Marauder, the AAF had sufficient B-25s to allow standardization."_

1935 - Project D - Bomber, Long Range (BLR)

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## wuzak (Mar 16, 2020)

Bear in mind that significant weight had to be taken out of the B-25 to enable it to take off the carrier.



fubar57 said:


> A B-25 needed 3795ft. to clear 50yds (this site). A B-26 needed 6100ft. Martin B-26G Marauder



The Doolittle raiders were B-25Bs.

The B-26G was introduced in 1944? 

The equivalent B-26 was the B-26 or B-26A. These didn't have the increased wing span (introduced with the B-26B-10 the month after the raid took place), nor did they have the wing incidence change (which happened in the F in 1944). They also were about 2,000lbs lighter empty, and 4,000lbs lighter at gross weight and MTOW.

The take-off run to clear a 50ft obstacle for the B-26 was 2,500ft (tested with a 12mph wind)
http://www.wwiiaircraftperformance.org/B-26/B-26_40-1361_PHQ-M-19-1184-A.pdf

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## Reggie_Mental (Mar 17, 2020)

When the US enetered the war in December 1941 it had still not fully emerged from the Wall street crash and the depression era. When industry suddenly got a boost by the war everybody was hungry, the manufacturers and the workers, many of whom were unionised and wages rose rapidly. This sort of Military Keynesianism led to overproduction and oversupply, and post war the military industrial complex pushed for and got a 'cold war' to continue it's arms race. Eisenhower warned of the dangers of this in a state of the nation speech. Sadly he was ignored.

Martin Luther King observed long ago that the US will not advance social democracy and justice whilst spending the lion's share of it's federal taxpayer dollars on a giant war machine. (Fully 56% of which is now spent on defence!)


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## GrauGeist (Mar 17, 2020)

What a load of horse-sh!t.

The cold war was the result of appeasing Stalin, who had global aims. Not some stupid Rothschild mega-capatalist conspiracy.

As far as SJW "Social Democracy" catch-word comment goes, the U.S. is a REPUBLIC, not a Democracy.

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## FLYBOYJ (Mar 17, 2020)

Reggie_Mental said:


> When the US enetered the war in December 1941 it had still not fully emerged from the Wall street crash and the depression era. When industry suddenly got a boost by the war everybody was hungry, the manufacturers and the workers, many of whom were unionised and wages rose rapidly. This sort of Military Keynesianism led to overproduction and oversupply, and post war the military industrial complex pushed for and got a 'cold war' to continue it's arms race. Eisenhower warned of the dangers of this in a state of the nation speech. Sadly he was ignored.
> 
> Martin Luther King observed long ago that the US will not advance social democracy and justice whilst spending the lion's share of it's federal taxpayer dollars on a giant war machine. (Fully 56% of which is now spent on defence!)



*WHAT THE HELL DOES MARTIN LUTHER KING HAVE TO DO WITH THE B-25 OR B-26?!?!? *

(BTW - your 56% statement is BS - learn the term "discretionary spending.")

Stick to the subject matter. Your political opinions and conspiracy theories will not be welcomed on this forum!

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## Peter Gunn (Mar 17, 2020)

From _Wiki_ (I know), but I suspected other ships were considered:

"Doolittle also considered the *Martin B-26 Marauder, Douglas B-18 Bolo*, and *Douglas B-23 Dragon*, but the B-26 had questionable takeoff characteristics from a carrier deck and the B-23's wingspan was nearly 50-percent greater than the B-25's, reducing the number that could be taken aboard a carrier and posing risks to the ship's superstructure. The B-18 was one of the final two types that Doolittle considered, and he rejected it for the same reason. The B-25 had yet to see combat, but tests indicated that it could fulfill the mission's requirements."

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## Admiral Beez (Mar 17, 2020)

FLYBOYJ said:


> *"Circular Proposal 39-640"*
> 
> _"Although opinion in the AAF placed special stress on strategic bombardment as the prime mission of an air force, the dominant view in the War Department General Staff was officially stated as late as October 1938 in these terms: "the Infantry Division continues to be the basic combat element by which battles are won, the necessary enemy field forces destroyed, and captured territory held." It followed that the primary function of Army aviation was the support of groumi forces in battle. And from this emphasis came the influences which gave shape to the A-20, the A-26, and the more famous B-25 and B-26, all of them designed basically for a supporting mission._
> 
> ...


Thanks for this 

 FLYBOYJ
it's very informative. Cheaper, faster, sufficient bombload and in plentiful supply - sounds good to me. 

So, the spec the B-26 was designed against didn't call for short or rough field ops? I thought I'd read somewhere that was a requirement for medium vs heavy bombers.


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## Admiral Beez (Mar 17, 2020)

Peter Gunn said:


> From _Wiki_ (I know), but I suspected other ships were considered:
> 
> "Doolittle also considered the *Martin B-26 Marauder, Douglas B-18 Bolo*, and *Douglas B-23 Dragon*,


An attack rather than bomber designation, but what about the Douglas A-20 Havoc/Boston?


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## GrauGeist (Mar 17, 2020)

The B-25 had a longer range than the A-20


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## Shortround6 (Mar 17, 2020)

Admiral Beez said:


> An attack rather than bomber designation, but what about the Douglas A-20 Havoc/Boston?



There is a fair amount of information about all of these planes easily accessible on the internet. 
A very good starting place is 

American Military Aircraft 

He takes a number of older books and condenses the accounts/information. If you take the time to read the various entries (the A-20 has 29 pages/entries) some of which are quite short you get a very good "back picture" of what was going on.

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## Zipper730 (Mar 18, 2020)

It's my view that there was little need for the B-26 to be honest in the war. The B-25 seemed to be able to do almost everything the B-26 could do, except carry the same load. They had the same range, similar speeds for most purposes.

They weren't part of the strategic bomber force where a lot of hitting power is actually needed, and for tactical purposes, both had adequate bomb-loads, firepower, and had about the same range.


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## Denniss (Mar 18, 2020)

Smells a bit like Ju 88 and Do 217 on the other side, similar range but heavier and higher bomb load. In my opinion both Do 217 and B-26 were better for the level bomber job whereas the somewhat better maneuverability of the Ju 88/B-25 made them better in other jobs.

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## RagTag (Mar 28, 2020)

Zipper730 said:


> It's my view that there was little need for the B-26 to be honest in the war. The B-25 seemed to be able to do almost everything the B-26 could do, except carry the same load. They had the same range, similar speeds for most purposes.
> 
> They weren't part of the strategic bomber force where a lot of hitting power is actually needed, and for tactical purposes, both had adequate bomb-loads, firepower, and had about the same range.


I think Jimmy Doolittle would demur.

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