B25 or B26, which was the better bomber?

[swampyankee]

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.

 

[MIflyer]

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.

 

[wuzak]

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.

 

[tomo pauk]

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?

 

[Zipper730]

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

1. 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
2. I figure the decision to keep the wing-span/area small was to decrease drag for high-speed. It certainly had low-speed penalties
3. 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.
4. 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?

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.

 

[MIflyer]

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.

 

[tomo pauk]

1. 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
2. I figure the decision to keep the wing-span/area small was to decrease drag for high-speed. It certainly had low-speed penalties
3. 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.
4. 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.
How would it compare with the B-25?

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?

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.

 

[Zipper730]

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...

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...

 

[Airframes]

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.

 

[GregP]

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.

 

[wuzak]

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

 

[wuzak]

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.

 

[Greg Boeser]

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.

 

[Greg Boeser]

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.

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.

 

[Greg Boeser]

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

 

[Zipper730]

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...

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

 

[Ascent]

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.

 

[MIflyer]

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.

 

[Airframes]

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.

 

[Zipper730]

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...

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

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.