B-26 Marauder Information

[Maty12]

Hi all,

My name's Matt, and I'm planning on making 3d models of the short-wing B-26 Marauder variants (B-26, B-26A, B-26B, B-26B-2 to B-26B-4). I've been doing research on the aircraft (along with a few other planes) for around 4 years on and off, and have recently been more dedicated to finding information on it. I originally started posting about my effort to find information on these planes on ww2aircraft.net, and a member there recommended I try posting here as well.

I've been putting all technical information I find on an excel spreadsheet, and I update it quite often. This includes the list of all fuselage and wing stations, along with short descriptions of what can be found there, the limits of movement for control surfaces and other similar information, and the angles and dimensions of most components (still WIP).

I'm making this thread both to share my findings and because there's a lot of things I still don't know, and was hoping to talk to someone with access to either diagrams and documents or a B-26 currently in restoration. The most important information I'm lacking are actual dimensions of parts, especially fuselage and nacelle frames, windows, landing gear components and flap components.

A few findings I wanted to highlight:
-The B-26's fuselage and nacelle are based on NACA airfoils, specifically the 00xx-64 series, with a few modifications.
-The change in the aircraft's attitude while parked between early and intermediate variants (short wing models vs all models prior to the B-26F) is due to the nose landing gear strut being moved lower on the fuselage (not lengthened). This is also why the small bulge on the bottom of the forward fuselage plane appeared in later variants.
-The vertical and horizontal stabilizers and their control surfaces were not redesigned for the long wing variants, the old versions were simply fitted with extensions at their original attachment points.
-Both early and intermediate aircraft's wings have the same angle for the leading edge and the same chord at Station 46 (the point where the outer wing panels attach to the center wing). The long wing models changed the angle of the trailing edge to increase the chord at the tips and allow for the wing to be extended. The new wingtip still attaches at the same location on the wing (Station 364), but is significantly longer.
-Very little of the fuselage was modified between these variants and most frames seem to stay the same up until nearing the end of the tail section, the biggest changes being due to the addition of the tail turret.

List of documents I currently have access to:
-B-26/B-26A Flight Manual
-B-26/B-26A Service Manual
-RB-26/RB-26A/RB-26B Erection & Maintenance Manual/Service Manual (Both are exactly the same, just have different covers)
-B-26B-1/C Parts Catalog (Weirdly no dimensions and no 3-views/orthographic projections)
-B-26B-1/C Erection & Maintenance Manual? (Cover and some pages are missing, I don't know. Also no dimensions and no 3-views)
-B-26F/G Flight Manual
-B-26/B-26A/B-26B Wing Station Diagram
-B-26B-1/C Wing Station Diagram
-B-26B Fuselage Station Diagram
-B-26B-1/C Fuselage Station Diagram
-B-26B-1/C Horizontal Stabilizer Station Diagram
-B-26B-1/C Vertical Stabilizer Station Diagram
-A low resolution/hard to read copy of the B-26/B-26A general arrangement drawing (Martin Drawing No. 5K-17988, extremely useful)
-Pictures of one out of four sheets of the B-26/B-26A inboard profile (Martin Drawing No. AP-B-26-075, or maybe -025, sadly most of the information I need is in the other three sheets)
-Pictures of B-26B-1 general arrangement drawing (extremely useful)

Approach to the Excel spreadsheet:
Information on the B-26 isn't extremely hard to find, but it tends to be very contradictory.
-"Fuselage Stations" and "Wing Stations" are a result of comparing the fuselage and wing station diagrams between variants, along with information from the manuals and observing photographs of aircraft in restoration with frames exposed.
-"Other Dimensions" is the section containing dimensions, angles and locations of parts, and I'd argue is the most important one. This section was made by comparing information listed on the two Martin-produced general arrangement drawings, using a lot of trigonometry (and making the parts in blender) since the dimensions and angles listed are in 3 different planes of reference: The thrust line, the fuselage zero lift line and the wing chord plane. This mix of trigonometry and building the parts in blender is how I arrived at some of my larger conclusions regarding part compatibility between versions of the aircraft.

I hope this thread is interesting, and look forward to sharing more of my findings about this wonderful aircraft with you all. If anyone wants to add more information, ask questions, or has any suggestions, please let me know.

Edit: Rephrased some confusingly worded sentences, moving the link to the spreadsheet to here, since it was previously hard to find in the middle of the text: Excel Spreadsheet

[Mark Allen M]

Nice endeavor. All the best on your mission.

Here's a group of photos from my files that may be of interest. They are some random Martin B-26A production photos.

[url=https://flic.kr/p/2j8gexJ]

[Maty12]

Nice endeavor. All the best on your mission.

Here's a group of photos from my files that may be of interest. They are some random Martin B-26A production photos.

Thank you very much, Mark! These are quite helpful

[Dan K]

...I'm making this thread both to share my findings and because there's a lot of things I still don't know, and was hoping to talk to someone with access to either diagrams and documents or a B-26 currently in restoration. The most important information I'm lacking are actual dimensions of parts, especially fuselage and nacelle frames, windows, landing gear components and flap components...

Yes, marvelous endeavor!

Should we assume you've already made contact with Pat Rodgers at Aircraft Restoration Services?

https://www.facebook.com/Aircraft-Resto ... 001068341/

[Maty12]

...I'm making this thread both to share my findings and because there's a lot of things I still don't know, and was hoping to talk to someone with access to either diagrams and documents or a B-26 currently in restoration. The most important information I'm lacking are actual dimensions of parts, especially fuselage and nacelle frames, windows, landing gear components and flap components...

Yes, marvelous endeavor!

Should we assume you've already made contact with Pat Rodgers at Aircraft Restoration Services?

https://www.facebook.com/Aircraft-Resto ... 001068341/

I haven't yet. Andrew Boehly from the Pima Air & Space Museum did tell me their B-26 was with Pat last time we spoke, but I forgot to message him. Will do so as soon as I can

[Clifford Bossie]

Great stuff! And interesting. Thank you for taking the time to share your work.

[wolf]

B-26 production line video

https://archive.org/details/gov.archives.arc.38638

https://archive.org/details/0505_Bomber_10_11_25_08

[Archer]

https://flic.kr/p/2j8cfWK
This one doesn't appear to be a B-26, B-24 perhaps?
Great set of photos!

[Maty12]

Great stuff! And interesting. Thank you for taking the time to share your work.

Thank you, I look forward to sharing my next findings.

B-26 production line video

https://archive.org/details/gov.archives.arc.38638

https://archive.org/details/0505_Bomber_10_11_25_08

Very interesting, a lot of great shots of the assembly line! For some reason I thought Martin's "Building a Bomber" and "Bomber" were the same film, but the shots in the two are very different and so is the narration. Kinda funny seeing the narrator talk about the plane having "so many guns we're not even allowed to talk about it", when talking about a plane that only carried 4-5.

https://flic.kr/p/2j8cfWK
This one doesn't appear to be a B-26, B-24 perhaps?
Great set of photos!

I believe so, yes. There is a B-26 in the background, and in a few of the other B-26 shots you can see this B-24 in the background. I wonder why it's in the plant.

[wingsandrotorspilot]

PBM Mariner is the aircraft in the background.

Marty, PM me, and I'll try to answer all of your questions!

Pat Rodgers

[Adam Kline]

Love the topic. Good luck

[Steve Nelson]

https://flic.kr/p/2j8cfWK
This one doesn't appear to be a B-26, B-24 perhaps?
Great set of photos!

The spar has "B24A" stenciled on it. Definitely looks like an early "round nacelle" Liberator.

SN

[Maty12]

Forgot to update the thread here! Posted the following updates on the original thread over on ww2aircraft.net:

I have been in contact with Pat Rodgers, who has been helping me with pictures and some measurements. Based on those, it would appear that the nose gear trunnion was originally placed on station 72 3/4", right under the cockpit floor, and that the later versions moved it 6" lower and 3 3/4" forwards, placing it at station 69" on these versions. The angle that the strut is mounted also changed from 11 degrees from the fuselage centerline to roughly 7.5 degrees, so that it could fit in the compartment without further modification.

The main landing gear is also mounted at 11 degrees, but the bottom portion of the strut is angled forwards by 9 degrees (to fit in the wheel well, I assume). The drag struts seem to be mounted at 45 degrees, but these angles are based on less accurate diagrams, so they could be incorrect. The service manual for the early B-26s lists this angle as 60 degrees, but the same manual also incorrectly lists the wing chord at the root as 154.501", so I'm taking that with a grain of salt.

These findings would explain why both main and nose landing gear legs seems to be mounted at the same angle in photos of early B-26s, but very different angles in photos of intermediate (B-26B-1/B-26C) aircraft. The difference seems to increase even further on the late (B-26F/G) aircraft, most likely due to the change in wing incidence, but I have not verified this yet.

I have since updated the excel spreadsheet with this information. It also contains some theories I have regarding the design of the nacelles and fuselage airfoils, that I currently do not have enough evidence to confirm or disprove. These mostly come from the fact that a lot of dimensions are very close to being multiples or divisors of 7 or 14.

I'm going to attempt to get some blueprints on microfilm from NASM or the Smithsonian, depending on what I can afford, as I'd like to be able to make at least some individual parts fully accurate, and then will most likely eyeball less noticeable areas.

Cheers,
-Matt

[TriangleP]

Do you have any drawings or diagrams showing the MG brackets inside package gun pods?

[Maty12]

Do you have any drawings or diagrams showing the MG brackets inside package gun pods?

For the actual brackets, I do not. I do however have this diagram for the heating elements for the guns, hope it's useful.

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