B-26 Engineering Data/Technical Information (From Martin's Own Blueprints)

[Maty12]

What a job you took on.

It is gonna take a while to say the least, lol

I find this one interesting as when we recovered the three B-26's from near the Liard River in Canada they all had metal flaps. All three were B-26 period aircraft.

View attachment 808683

That one's on me, I should have clarified when the wooden flaps were introduced as the case history skipped over it. Wooden flaps were introduced on the first B-26C along with the new long wing and only 50 sets were manufactured before it was decided to switch back to metal. They were only fitted to B-26C-5s 41-34673 through 34722. All Baltimore-built B-26s had metal flaps, as did all B-26Cs manufactured after these 50.

I do plan on eventually making just one large sheet that includes all changes (even the ones the case history skipped).

 

[MiTasol]

Thank you.

 

[Maty12]

Spent the past hour and a half trying to find a source for a claim I had written down only for it to turn out to be right in front of me. While I haven't seen a reason given for switching to wooden flaps, the reason for switching back to metal flaps is given on page 996 of the case history:

"4 December 1942- B-26C, contract 19342. Contractor proposes to change from wood to metal wing flaps. Authority for purchase 333910 written for 1150 airplanes" (p. 994)

"9 March 1943- Contract 19342, B-26C. Authority for Purchase 333910 for 1150 metal wing flaps initiated by J. H. Carter, Major, Air Corps. Authorized - unsatisfactory performance of wood flaps on A-30 airplanes" (p. 996).

The 1150 were off the initial B-26C contract for 1200 airplanes. The B-26C's 3-view drawing lists the parts numbers for both kinds of wing flaps, and lists the GLM production numbers and USAAF serial numbers for the aircraft fitted with each type.

 

[MiTasol]

Thanks.

I must admit I had to search to find the A-30 was the Martin Baltimore in US service.

 

[Maty12]

Not an update on my part (though I am currently investigating the B-26 nose gear), but Aero Trader has donated several B-26 manuals and some training workbooks to the Air Corps Library, including the overhaul manual for the B-26, B-26A & B-26B (01-35EA-3), a structural repair manual that covers both short and long wing models (01-35E-3, mistakenly tagged as 01-35E-4), a 1943 pilot's manual for the B-26, B-26A and B-26B (that mainly focuses on the B model, one of several manuals sharing the 01-35EA-1 designation), and a parts catalog for all long wing models (01-35E-4), among other things. The manuals and technical orders donated years ago by Jay Wisler are also still there and a great source of information.

 

[Maty12]

Hi all, wanted to give a brief update on things to come:
1- I believe I've sorted out the change in the nose gear, by comparing dimensions from an E&M manual I recently received with the 3-view drawings for the B-26C and B-26G. The discrepancy between drawing R-346925 and real life photos does not exist, they agree fully. Embarrassingly, it took me 5 years to realize that the photos I was looking at of the wheel well had actually been rotated 90 degrees. What I thought was the distance from the mounting trunnion to the forward bulkhead was actually the distance from the trunnion to the roof of the nose gear compartment. I will incorporate this into the B-26 skeletons soon, as well as remove some unnecessary clutter from them. Speaking of, have these been useful?

2- I plan on writing about the different oxygen systems fitted to the B-26. I was asked to look into this by the lads at Boxted and found the results pretty interesting. A fixed system was used in early aircraft, while later models switched to a portable system that was commonly removed before combat.

3- I also plan on writing about the different autopilot systems, but this has turned out to be far harder to research than I thought and I kept finding very little on the system fitted to the early B-26s, Norden's AFCE, whose controls were only described in the vaguest of terms and whose functioning was never explained. One B-26B manual comically has only one paragraph about it while talking at length about the Minneapolis-Honeywell AFCES (Type C-1) system that replaced it. This pattern repeats itself in B-25 manuals as well, which mention AFCE briefly and then describe the Sperry autopilot fitted to other ships in great detail. I finally found out why thanks to an E&M manual for early B-25s at aircorpslibrary:

"Note: Because of the confidential nature of the A.F.C.E., no further information regarding it can be given."

This could also be why the bombing system/autopilot drawing, R-364175, is not in the Smithsonian's collection (or it could just be lost, several drawings are). The Parts Catalogs show very little of the installation either. The 3-view drawings for the B-26B and B-26B1 both give the following warning about it:

"This is a confidential drawing. Prints and information concerning this drawing may be obtained ONLY from the Air Corps. (Local Office)."

I think I understand how that system works well enough to explain it, but could simply not know what I don't know, so I hope to find out more first, though have no idea where to look. I was originally going to post about this months ago when I started to dig deeper.

 

[Snautzer01]

Amazing work.

 

[Maty12]

Amazing work.

Thank you!

 

[Ivan1GFP]

A bit over 15 years ago, I started doing some 3D modelling of the Marauder (late production B series) for a flight simulator project.
I ended up with many of the same types of drawings you have posted, but since my information was from books, the accuracy was much less reliable and quite contradictory in places. This interest began because of many discussions with my neighbor who had flown them in the 320 BG during the war. While he was still alive, my capabilities for doing such a complicated model were not up to the task and when I finally began, he had been gone almost a decade.

- Ivan.

 

[Maty12]

A bit over 15 years ago, I started doing some 3D modelling of the Marauder (late production B series) for a flight simulator project.
I ended up with many of the same types of drawings you have posted, but since my information was from books, the accuracy was much less reliable and quite contradictory in places. This interest began because of many discussions with my neighbor who had flown them in the 320 BG during the war. While he was still alive, my capabilities for doing such a complicated model were not up to the task and when I finally began, he had been gone almost a decade.

- Ivan.

Thanks for sharing, Ivan. I'd be interested in hearing more about your model sometime. I haven't had the chance to meet anyone who flew in Marauders myself, and hope I still can.

 

[cvairwerks]

Thanks for sharing, Ivan. I'd be interested in hearing more about your model sometime. I haven't had the chance to meet anyone who flew in Marauders myself, and hope I still can.

Maty, you're running out of time. The last Marauders were withdrawn from service in France, in 1947. A 20 year old that flew one in 1947, would be 98 years old...

 

[Ivan1GFP]

Thanks for sharing, Ivan. I'd be interested in hearing more about your model sometime. I haven't had the chance to meet anyone who flew in Marauders myself, and hope I still can.

My 3D model actually didn't get very far. The basics were not difficult but the Marauder has a bunch of areas that involve lots of compound curves. The worst of them in my opinion is the two large intakes with dust filters on top of the engines The detail needed for a flight simulator model isn't really all that much, especially for CFS1, so what I was trying for was probably a lot less than what you are going for.

Here is a rather famous picture of my friend. This is not the aircraft he normally flew.

- Ivan.

 

[Maty12]

Maty, you're running out of time. The last Marauders were withdrawn from service in France, in 1947. A 20 year old that flew one in 1947, would be 98 years old...

I am aware, unfortunately.

My 3D model actually didn't get very far. The basics were not difficult but the Marauder has a bunch of areas that involve lots of compound curves. The worst of them in my opinion is the two large intakes with dust filters on top of the engines The detail needed for a flight simulator model isn't really all that much, especially for CFS1, so what I was trying for was probably a lot less than what you are going for.

Here is a rather famous picture of my friend. This is not the aircraft he normally flew.

- Ivan.

It is indeed mainly compound curves, the nacelles and empennage being particularly complex. That's a great photo!

 

[Ivan1GFP]

I am aware, unfortunately.


It is indeed mainly compound curves, the nacelles and empennage being particularly complex. That's a great photo!

Little Sherry was Battle Number 09. My friend mostly flew a B-26G Battle Number 06 Sandra Lee.

B-26 320th Bomb Group Serial Numbers

Martin B-26 Marauder.The 320th Bomb Group flew the B-26 in WWII. Initially stationed in North Africa, the unit late moved to Sardina, Corsica, and finally to France

320thbg.org

I built a 1/48 scale Monogram B-26 for him at one point, and it was interesting the kinds of things he remembered and the things he did not.
The Battle Number 06 was something that stuck in his mind. The name on the nose art was something he did not recall, so we we went through a lot of old photographs and concluded it must have been "Sandra Lee". The BN was prominent on the tail and beside it was the serial number of the aircraft 334252, so we could tell what production batch it was from and such.
The model kit had an object about the size of a very large watermelon behind the pilot's seat. I was curious what that was. Col. Boblitt told me there was nothing back there because that is where his dog sat. From what I found out later, this was most likely an oxygen tank.
The photographs we were looking at were not big (about the size of polaroids) but they had a lot more definition and detail than the scans that are posted at the 320th BG site.
Here is what I believe is the best picture of BN 06 Sara Lee from the 320 BG site.

A couple things can be noted: The hatches over the ventral gun position are often not installed. The common practice was to only retain one of the pair of cheek guns on each side and it didn't seem to matter whether the upper or lower cheek gun was kept.

- Ivan.

 

[Maty12]

Little Sherry was Battle Number 09. My friend mostly flew a B-26G Battle Number 06 Sandra Lee.

B-26 320th Bomb Group Serial Numbers

Martin B-26 Marauder.The 320th Bomb Group flew the B-26 in WWII. Initially stationed in North Africa, the unit late moved to Sardina, Corsica, and finally to France

320thbg.org

I built a 1/48 scale Monogram B-26 for him at one point, and it was interesting the kinds of things he remembered and the things he did not.
The Battle Number 06 was something that stuck in his mind. The name on the nose art was something he did not recall, so we we went through a lot of old photographs and concluded it must have been "Sandra Lee". The BN was prominent on the tail and beside it was the serial number of the aircraft 334252, so we could tell what production batch it was from and such.
The model kit had an object about the size of a very large watermelon behind the pilot's seat. I was curious what that was. Col. Boblitt told me there was nothing back there because that is where his dog sat. From what I found out later, this was most likely an oxygen tank.
The photographs we were looking at were not big (about the size of polaroids) but they had a lot more definition and detail than the scans that are posted at the 320th BG site.
Here is what I believe is the best picture of BN 06 Sara Lee from the 320 BG site.

A couple things can be noted: The hatches over the ventral gun position are often not installed. The common practice was to only retain one of the pair of cheek guns on each side and it didn't seem to matter whether the upper or lower cheek gun was kept.

- Ivan.

Thanks for the info! I have saved quite a few photos of Sandra Lee over the years from the web, many of them in color too. I wonder if they're from Joe Kingsbury of the 441st, who took many of the color photos of the 320th BG. I bought a physical copy of Charles O'Mahoney's article "Me and My Gal" a while back on ebay which has many of Kingsbury's photos, including the ones from the 320th BG website.

An older post you made about Col. Boblitt and the oxygen tank (or more accurately, the lack there of) was one of the few mentions I could find of oxygen systems in long-wing B-26s at all back when I was tasked with researching it! The few first-hand accounts I could find all also say there was no oxygen system. The part included in the kit is likely one of the three tanks of the "portable oxygen system" (the other two are in the navigator's compartment) that I briefly mentioned in post #26, which Martin's Equipment Installation Drawing for the B-26B1 (R-344115) calls the "ferry oxygen apparatus". Each installation has its own part number and they are named individually as for the pilot, co-pilot and navigator. Sadly that drawing is in a roll that was photographed improperly decades ago so the part numbers are too blurry to read. The three units are identical, and are comprised of an F-1 tank with an A-12 oxygen regulator and K-1 pressure gauge.

Given the "ferry oxygen apparatus" name and the fact that there's only three of them with no interconnection or larger delivery system despite B-26 crews having 5-7 members, my understanding is that the equipment was only used for long ferry flights. I can see why this would be needed, as O'Mahoney explains in the article that the lack of oxygen equipment in the B-26 led to headaches on prolonged missions above 10,000 ft:
"And we didn't carry oxygen. Missions that kept us at 12,000 to 14,000 feet for long stretches guaranteed a booming headache by the time we landed"

Carl H. Moore's book Flying the B-26 Marauder Over Europe also backs up this "ferry only" installation, as his only mention of oxygen in the entire book is during the ferry flight from the US:
"To clear all clouds, Tom took us up to 11,000 feet. The air was a bit thin, so we occasionally took some oxygen from a portable tank just to keep us alert."

While I don't have documents specifically stating this, I would imagine the equipment was simply removed once the ferry flights were completed. The bottles are simply strapped to the floor on wooden blocks, and not in any way connected to the airplanes themselves.

So why was this part included in the model kit? Most likely because a photo of it behind the copilot's seat is in several of the manuals, including the POH for the B-26B1 & C (01-35EB-1), the POH for the F & G (01-35EC-1) and a pilot training manual that covers all long-wing models (see page 56). It doesn't help that the manuals explain nothing about the system. The E&M manual for all long-wing models (01-35E-2) describes its components, inspections and repair, but not when it was fitted or used.

The parts catalogs (01-35EB-4 and 01-35E-4) list the parts for the older fixed/permanent system instead. I will describe that system in detail and explain the context behind the switch in oxygen systems once my current semester of uni ends. Variations of it were fitted from the first B-26 to the last B-26B-10 (deleted from B-26B-15 onwards), and to some B-26Cs. It used six interconnected bottles with 8-9 delivery stations that masks could be connected to.

-Maty

 

[Ivan1GFP]

In my prior post, 334252 can clearly be seen on the fin of the aircraft along with the BN 06. The nose art is not very clear and wasn't all that distinct even in the original photograph. We could easily tell what it was not though. Once we had decided it was probably "Sandra Lee", getting a detail shot of the nose art was very easy.
Here is a close up shot of the nose of "Sandra Lee". This gave me enough information to hand letter the name. I cannot recall if I had to paint the 320 BG emblem or whether it was a decal. I do remember that the real thing came in a couple different variations. This one is just the emblem. Others often had the motto on a white ribbon going through the emblem. Motto was "Finis Origine Pendet" or "The End Depends on the Beginning". This is not Col. Boblitt's crew. Sandra Lee survived to VE Day.

This is a photograph of an aircraft with the 320 BG Emblem with the White Ribbon I described earlier. The man most worthy of note in this photograph is Joe Kingsbury (2nd from Left) who took most of the color photographs of the 320 BG planes and crews. If he had not made the effort to obtain color film and take his photographs, we would not have the wonderful photographic record we do today.

- Ivan.

 

[Greg Boeser]

In my prior post, 334252 can clearly be seen on the fin of the aircraft along with the BN 06. The nose art is not very clear and wasn't all that distinct even in the original photograph. We could easily tell what it was not though. Once we had decided it was probably "Sandra Lee", getting a detail shot of the nose art was very easy.
Here is a close up shot of the nose of "Sandra Lee". This gave me enough information to hand letter the name. I cannot recall if I had to paint the 320 BG emblem or whether it was a decal. I do remember that the real thing came in a couple different variations. This one is just the emblem. Others often had the motto on a white ribbon going through the emblem. Motto was "Finis Origine Pendet" or "The End Depends on the Beginning". This is not Col. Boblitt's crew. Sandra Lee survived to VE Day.
View attachment 835048

This is a photograph of an aircraft with the 320 BG Emblem with the White Ribbon I described earlier. The man most worthy of note in this photograph is Joe Kingsbury (2nd from Left) who took most of the color photographs of the 320 BG planes and crews. If he had not made the effort to obtain color film and take his photographs, we would not have the wonderful photographic record we do today.

View attachment 835051

- Ivan.

What strikes me here is the strafer plate is shiny and new. This suggests to me that they were retrofitted on older block numbers, as well as on new builds.

 

[Ivan1GFP]

Thanks for the info! I have saved quite a few photos of Sandra Lee over the years from the web, many of them in color too. I wonder if they're from Joe Kingsbury of the 441st, who took many of the color photos of the 320th BG. I bought a physical copy of Charles O'Mahoney's article "Me and My Gal" a while back on ebay which has many of Kingsbury's photos, including the ones from the 320th BG website.

I have never actually found all that many photographs of "Sandra Lee" though there were a few of BN 06 in Col Boblitt's collection.
I believe the vast majority of the color photographs of the 320th were by Joe Kingsbury.
I was actually looking for mostly detail shots of the aircraft for modelling purposes. I believe Charles O'Mahony was the CO of the 441st. He typically flew "Miss Manchester" BN 14. I believe Mrs. Boblitt kept in touch with some of the people from the 320 BG. She told me probably almost 10 years ago when she heard that O'Mahony had died. Up to that point I had been hoping to get one of his books and have it signed by him.

An older post you made about Col. Boblitt and the oxygen tank (or more accurately, the lack there of) was one of the few mentions I could find of oxygen systems in long-wing B-26s at all back when I was tasked with researching it! The few first-hand accounts I could find all also say there was no oxygen system. The part included in the kit is likely one of the three tanks of the "portable oxygen system" (the other two are in the navigator's compartment) that I briefly mentioned in post #26, which Martin's Equipment Installation Drawing for the B-26B1 (R-344115) calls the "ferry oxygen apparatus". Each installation has its own part number and they are named individually as for the pilot, co-pilot and navigator. Sadly that drawing is in a roll that was photographed improperly decades ago so the part numbers are too blurry to read. The three units are identical, and are comprised of an F-1 tank with an A-12 oxygen regulator and K-1 pressure gauge.

Given the "ferry oxygen apparatus" name and the fact that there's only three of them with no interconnection or larger delivery system despite B-26 crews having 5-7 members, my understanding is that the equipment was only used for long ferry flights. I can see why this would be needed, as O'Mahoney explains in the article that the lack of oxygen equipment in the B-26 led to headaches on prolonged missions above 10,000 ft:
"And we didn't carry oxygen. Missions that kept us at 12,000 to 14,000 feet for long stretches guaranteed a booming headache by the time we landed"

Carl H. Moore's book Flying the B-26 Marauder Over Europe also backs up this "ferry only" installation, as his only mention of oxygen in the entire book is during the ferry flight from the US:
"To clear all clouds, Tom took us up to 11,000 feet. The air was a bit thin, so we occasionally took some oxygen from a portable tank just to keep us alert."

While I don't have documents specifically stating this, I would imagine the equipment was simply removed once the ferry flights were completed. The bottles are simply strapped to the floor on wooden blocks, and not in any way connected to the airplanes themselves.

So why was this part included in the model kit? Most likely because a photo of it behind the copilot's seat is in several of the manuals, including the POH for the B-26B1 & C (01-35EB-1), the POH for the F & G (01-35EC-1) and a pilot training manual that covers all long-wing models (see page 56). It doesn't help that the manuals explain nothing about the system. The E&M manual for all long-wing models (01-35E-2) describes its components, inspections and repair, but not when it was fitted or used.

The parts catalogs (01-35EB-4 and 01-35E-4) list the parts for the older fixed/permanent system instead. I will describe that system in detail and explain the context behind the switch in oxygen systems once my current semester of uni ends. Variations of it were fitted from the first B-26 to the last B-26B-10 (deleted from B-26B-15 onwards), and to some B-26Cs. It used six interconnected bottles with 8-9 delivery stations that masks could be connected to.

-Maty

The "part" on the Monogram kit isn't actually a separate part. It is moulded as part of the floor behind the pilot's seat. There is no matching tank on the copilot's side. As for portable, this thing was VERY Large. About the size of a very large watermelon as I mentioned earlier. It wasn't something I would think about as portable inside the aircraft.
One could of course have sawn the part off the floor and there was actually a resin version of the tank with a bit more detail as a substitute but keep in mind this was behind the pilot's seat and with a pilot and copilot in place and a closed canopy, nothing much really could be seen anyway. If I had chosen to remove the tank, it would have left a hole in the floor because the underside of the tank in the floor was hollow. I just chose not to mess with it. I was a bit more concerned at the time about how to get enough weight inside the model so it would sit on its nose gear and not collapse the main gear.

As for oxygen equipment, my impression is that it isn't absolutely essential below about 15,000 feet. I know I have been on a couple aerobatic flights that went up to just below 15,000 feet without oxygen. We were not up there long, but it didn't feel bad. As I understand it, most of the 320 BG's missions in Italy at least were conducted at fairly low altitude but high enough to leave the target in a shallow dive. The result was a bunch of bombers heading back to Allied lines at around 400 MPH. Not an easy intercept!

- Ivan.

 

[Ivan1GFP]

Here are a couple rather useful dimensional drawings. I have a lot more technical drawings on the B-26, way more than is reasonable to post here in a single thread.

- Ivan.

 

[cvairwerks]

On O2 tanks....Found a reference that 41-31973 thru 41-30272 carried (3) F-1 tanks, and each had it's own permanently mounted filling system. I also found references that showed permanently mounted O2 regulators in various C models. Filling ports were located in the bomb bay for all 3 systems.