Martin B-26 Marauder Project

I

Ivan

Charter Member
Hello All,

I have wanted to build a B-26 Marauder as flown by my friend and neighbour for quite some time. The original intent was for him to actually be able to fly his old plane in the simulator but he passed away a few years back. We all think those around us will always be there, but things never seem to work out that way.

Wallace Boblitt flew in the 320th Bomb Group 441st Squadron from Italy. His actual plane was a B-26G Serial Number 43-34252 in bare metal with the Tactical number 06. I built him a model of it (Revell 1/48 scale) many years ago. The name of the aircraft was "Sandra Lee" lettered in black script on the nose. He asked me to mark the aircraft with 51 missions completed (Little yellow bombs by the cockpit).

Colonel Boblitt could not remember the name that was on the side of his aircraft. We spent a fair amount of time going over wartime photographs (ancient stuff) trying to figure out what the gray blur on the nose really said. The Tactical number was obvious as was the serial number under it. He remembered it was a G Model which the serial number confirmed.

My intention is to build a "Generic" B-26 Marauder with his plane's markings. The visual model will be closer to a mid or late B model with paint for "06". The performance will be closer to that for an early B model which perhaps is a bit unrealistic, but I'll call this "artistic license".

Attached below are what I believe to be useful drawings and information for this project.

Good Evening.
- Ivan.
 
now, this is exciting!
i know it is a pain in the hindy
and a lot more work for you,
but i hope you will take the time
to share the build process with us.

I LOVE THE TWINS!!!!

-------:kilroy:--------

i am sorry to hear of the passing of Colonel Boblitt.
this project will be a fitting tribute.
RIP
 
Ivan said:
Hello All,

(...)

Colonel Boblitt could not remember the name that was on the side of his aircraft. We spent a fair amount of time going over wartime photographs (ancient stuff) trying to figure out what the gray blur on the nose really said. The Tactical number was obvious as was the serial number under it. He remembered it was a G Model which the serial number confirmed.

(...)
- Ivan.
Click to expand...

If you could send me the picture(s), I could try to decipher that name with some of my graphic tools. I'm pretty good at that game. No promises...

P.S. - A short search gave me this;

43-34252-B-26G-Marauder-12AF-320BG441BS-06-01.jpg


Can't make the name but, according to your post, it is "Sandra Lee" simply written in "script fashion".

Picture found HERE
 
Smilo,
This project WILL get complicated and I intend to finish it using SCASM which is really Hubbabubba's territory. He is a whole lot more knowledgeable than I am on the subject. I may post some status shots and a little description here and there, but it won't be a thorough coverage of the steps. That simply takes too much effort and takes attention away from the actual development.

Hubbabubba,
Wallace and I already looked through a LOT of photographs (some in a book called "Blue Battlefields" and some original prints) including the original of the one you posted. It doesn't get any clearer, you already found the best photograph of the plane. BTW, I don't own the photographs, Mrs. Boblitt does.
Here is a photograph of the nose of the aircraft. It is the first "Crew" photograph at the 320th site. Crews typically flew what was available. The aircraft commander here was "Red" Goeke.

This part isn't a mystery any more. Even the 320th site now agrees with our conclusion, though the serial numbers page still lists an incorrect tactical number.

Attached also is a photo of Wallace Boblitt aboard "Little Sherry" Tactical number 09. He was not very tall (about the same height as me 5'5") and there were stories of how he had to have blocks on the rudder pedals. Apparently this was no longer necessary when they switched to the B-26G because the rudder pedals were higher. I believe there is still a painting of 09 "Little Sherry" hanging on the wall in his house.

FWIW, He was the guy that got me into Combat Flight Simulator. I originally bought the game and for some reason the display didn't seem to work on my machine. I could not play the game. One day when I was over at his house, he showed me the CFS installation on his machine. It WORKED. It took a while but I finally figured out that he had a 3D graphics card installed and I didn't. I went out and bought a Voodoo 2 or Voodoo 3. Everything worked after that. The game had been sitting on my shelf for a couple months already and would have remained there if he hadn't done the little impromptu demo. Since then I have installed CFS over at their house several times even after he died.

....So for me being involved in CFS, you can blame Col. Boblitt.
- Ivan.
 
!I also found this profile from Mark Styling;

B-26.18.jpg


found HERE

And this photo from Google Book;

sandraleelarge.jpg


It was enlarged on screen and then screen-captured. Maybe you can recognize your ex-neighbor in the line-up?

OOOOPS! Maybe not, our posts criss-crossed each others.
 
Thanks for the comments, guys.

I don't think he was ever that much into the game. Neither was I at the time. I hadn't even played it yet. I had not seen the stock aircraft and didn't know about all the downloads available. It was just an amusing thing to show a neighbour with all the other memorabilia that he had.

Keep in mnd that when I started playing, the AI was sufficient to kill me just about every time if I didn't do it first by crashing. My simulator flying ability was such that I could not even land an airplane. Literally I flew for 6 months with just Take-offs but no landings until I finally decided to keep trying until I got it right, and that was done initially by figuring out where the final approach needed to be and just moving out there about two miles out to start the game. Forget the downwind and crosswind stuff.

That was why when my friend Trapper asked me to show him how to do a carrier landing, I executed one beautifully and even surprised myself. I also was not able to replicate that landing for a VERY long time. A proof of mastering an action is to be able to do it on demand. I flew the landing on demand. I found that I could not repeat.... What does THAT say about mastery?

- Ivan.
 
Back to the Marauder

In looking over the drawings, I see that they tend to be contradictory. The CoG under various conditions is listed in one drawing, but note that the side view in the same series has the points displayed in such a manner that they DO NOT match the dimensions stated.

Note that the linear dimensions aligned with the Thrust Line differ noticeably from those aligned with the Fuselage Centerline. They are listed to the thousandth of an inch but vary by more than an inch to an extent that is not supported by the geometry differences.

Note that the dimensions on the boundaries of the Wings and especiallly the Vertical Tail are not in agreement in any of the drawings.

A lot of the dimensions will be a "Best Guess" and Artistic License kind of thing because they are so contradictory.

Regarding the exact model to be built, It will be a long wing (71 foot rather than 65 foot) version with additional flaps outboard of the engine nacelles which were not on the versions before the B-26B-10.

It will be a "High Tail" version which means Late B series or later. It will have a longer nose gear strut though it will be missing the bump at the front of the nose gear that comes with these planes.

The Center of Gravity will be 60 inches behind the Wing Root's Leading Edge and even with the Fuselage's Vertical Centerline just to make it a nice even number for reference because everything else is relative to that point.

The Thrust Centerline will be level instead of inclined because we can't incline it in a CFS Flight model. The G model had an additional 3.5 degree positive incidence on the Wing and Engines but this will not be reflected.

A funny thing about this aircraft is that it has symmetrical airfoils. One wonders why this is the case and that perhaps it might have flown better with some Camber in the airfoil and reduced incidence. It was certainly NOT an aerobatic aircraft so didn't need to have lift while inverted.

- Ivan.
 
Dimensional and Other Drawings

Having Dimensional drawings is very nice. Having Station drawings is also very nice but I can't find them for the Marauder.

With either dimensional or station drawings, there are details that are not specified. The points we choose to use to approximate a curve may not be the same as those shown in the engineering drawing because THEY can stamp a curved piece of metal and we can't.

Attached are two more useful drawings for the B-26. They are not as good as I would like, but they are probably good enough. Note that the line quality of these scanned drawings are quite poor. This is partly due to the fact that I rotated them slightly to make the main axis of each drawing be perfectly horizontal to the pixel. If you check the centerline at the left and right sides of each drawing, you will see that they are aligned as they can be.

After this, the drawings are magnified to be 1 pixel == 0.01 Foot so dimensions can be directly scaled from them.

- Ivan.
 
Dimensional Drawings are Good if.....

Last night I made my first attempt at some basic "Jig" type reference parts for the Marauder. Because the "Blue" prints had the most dimension labels, I tried to use those to create a Wing, Stabiliser and Fin Template. The Wing was a bit difficult until I finally figured out that one of the numbers was in error. The Chord at the aircraft centerline is very wrong. The difference in height between the Wing Root Leading Edge and Wing Tip Leading Edge did not agree with the Dihedral Angle.

The Stabiliser was relatively easy because all of the drawings agreed.

The Fin was totally off when using the "Blue" prints. The profile was obviously wrong. It became more apparent when scaling the height off the aircraft centerline from the non-dimensional drawing. I found that the "Blue" print was around 3 FEET too short.

Sheesh!
- Ivan.
 
Hello Ivan:wavey:

I've been away from the PC for the whole week and had some catching-up to do. I have read your preceding posts and know your liking for "measured" plans.

I can't say that I follow you there (surprise!!!:icon_lol:). I'm more interested in having proportions respected than having, let's say, an air scoop at exactly 3.75" forward and 6.50" from the datum point. I have very little confidence in these measures. Who made them and under what circumstances anyway?

I know that some Japanese publications are very thorough in their measurements, but they are the exception.

Of course, your designing method does not rely on Andrea Cini's Template Part Creator like mine. Considering that, at scale 7, .25" is about as precise as you can get, getting the aircraft to "look the part" is, for me, more important than getting some obscure numbers coming from some unknown source to "fit in".

Your own measurements are a testimonial to that effect; the discrepancies you noted are plentiful. In your Veltro project, I over-imposed once two "up-view" to confirm my impressions that these two plans where depicting totally different airframes!

When in doubt, I will try to rely on the plan that looks to be closer to photographic evidence. For example, one of the Taifun plan I had was showing a faired tail wheel. The problem was that I had never seen one on any of the pictures!

Good luck in your project and give proper credit to your own sense over incomplete, if not plain false, numbers. Our "artistic license" is most of the time closer to reality.
 
Artistic License

Hi Hubbabubba,
Actually you might be surprised at how loosely I stick to "Precise" measurements. They are a start to locate the pieces of the plane relative to each other. The Template parts I create are a place to begin to see how the pieces relate and to avoid going too far along with a Project before finding out that things really don't look right.

If you remember the Macchi C.205 that was the recent Tutorial subject, the cross sections of the plane were mostly from a AF99 Structure. I needed to use precise measurements to start because to me, the plane always had a nose that was too long by appearance. The problem is that the eyeball tends to bring things more in line with our own impressions of how they should be and sometimes that isn't right. The end result with the C.205 is that its shape is pretty close (in my opinion) to the photographs I see even though I still think the nose is too long. If I had done it by eyeball, the nose would be considerably shorter and probably wrong.

I have had projects in which I have done things by eyeball such as the P-47 Thunderbolts. After a couple years, things just didn't quite look right so I checked against technical drawings and found that my cockpit was in the wrong place. No, I am not correcting it!

I also recently rebuilt the nose of my FW 190A because I found the cowl opening to be too big. The Corsairs I built also have problems because they are way too fat. A fix at this point is basically an entirely new build. That is what I would like to avoid.

I believe that when possible known dimensions should be used because without them, it is hard to tell by eye if angles are right. I don't think I could tell if the leading edge of this wing were a foot or two further forward or back. A book commented that telling the difference between the short (66 foot) or long (71 foot) wing on the Marauder was difficult. I have looked at photographs of the various fins and rudders on the Marauder and find it difficult to tell whether it is the long or short tail on a particular aircraft.

I agree with you that Photographs are the best reference. Drawings from the Aircraft Pilots or Erection and Maintenance manuals are next best and generally quite reliable. For a bomber, the loading chart is also quite good and MUST be accurate for safety reasons.

Don't worry, there is plenty of room for improvising no matter how much information is given.

- Ivan.
 
This is actually some pretty old work. I was experimenting to see how much I could accomplish with a single component and no bleeds. (There actually ARE a few bleeds, but they are very minor.)

The reality is that this single component won't allow good texturing or good detail, but I do think it was a fairly successful experiment. The dimensions are as correct as I can get them which means this will work as a reference for the Marauder.

- Ivan.
 
Symmetrical Airfoil

I commented earlier that I was a bit surprised by the symmetrical Airfoil used on this plane and that perhaps one with some camber and reduced incidence might have improved performance. Over the weekend, I found this article written by the designer of the aircraft that says pretty much the same thing which I did not know about earlier.

http://www.b26.com/page/truman_committee.htm

- Ivan.
 
Checking Proportions of the Cigar

The Marauder is pretty much made up of Round Cross Sections with Bulges added at various places. A few AF99 Structures gives a pretty good general idea of what the shape will be. I used a AF99 Utility I wrote to Mirror the Cowl to have an identical one for the other side. Before I had this Utility, Mirroring a Component was tedious and very error prone.

Keep in mind that this is just an examination of the shapes, Almost NOTHING in this screenshot will exist in the final product.

- Ivan.
 
Fin Template

Screenshot of the Manufacturing Jig for the Fin and Rudder. No the outlines from the specifications don't really line up this well. I just edited things by eyeball until things looked about right.

- Ivan.
 
i am very pleased to see this one
back on the front burner.
it will be interesting to watch
your work progress on the big twins.
 
Scale Modeler Magazine September 1969

Here is a photograph I found of my neighbour's plane.

This is from a very old magazine as can be seen from the Posting Title.

- Ivan.
 
The last version of the Marauder's Cowl was an interesting exercise in what could be done in a single component without any significant bleeds. There was no way it could end up in a real aircraft project though because it was not really possible to texture it in a way that would allow reasonable painting.

The shape also wasn't quite right. After looking over LOTS of photographs and trying to figure out the best way to simulate all the gradual curves around the Carbureter Intakes, this is what I came up with. It still loses a lot of the subtle curves, but I believe it is close enough to use in a final project.

This thing is expensive though. I figure it will cost 7 Components, a dozen or so Parts, and at least one Structure just to get it to a reasonable stage without significant bleeds and that is for each side. For me, this project isn't do-able without SCASM.

- Ivan.
 
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