3D Model B-33 Super Marauder (XB-33A)

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Maty12

Senior Airman
326
340
Nov 6, 2019
Evening everyone, figured it was about time I share some of my progress on this beast! I started work on it sometime in 2017 (if I remember correctly) and have been working on and off since. I've been using the original Martin blueprints and photos of the wooden mock-up as reference, which I got from Stan Piet at the Glenn L. Martin Museum. I chose to build the final revision of the model, but might also build some of the manned turret options and the old Marauder-esque plexiglas nose section. I'm using Blender 2.7 for all my modelling.

1.PNG2.PNG3.PNG4.PNG5.PNG6.PNG7.PNG8.PNG9.PNG10.PNG
Pictures (left to right): Front view, side view, top view, close-up on nose section, nose landing gear bay, nose landing gear retracted, main landing gear extended, main landing gear retracted, tail close-up with rudders 15 degrees to the right and elevators 10 degrees down, flaps fully extended (40 degrees).

For those interested in this aircraft, I'll take the time to address two small misconceptions about it:
I often see the aircraft modeled with a very large protrusion at the top of the engine nacelles to accommodate the landing gear (It's even present in the Anigrand 1:144 resin kit), which as far as I can tell was never actually used. Wind tunnel videos from NASA show a mock-up with smaller, less drag-inducing protrusions for the individual wheels. I've also seen people frequently call this 4-engined version the "XB-33A", but none of Martin's documents ever refer to it with the A designation, so I'm not sure where that comes from. That being said, finding performance information on this plane is a nightmare since information tends to be a mix of the original twin-engined version and the final version.

What still needs to be done on the model (in no particular order):
1- Add turrets
2- Rebuild the engine cowlings and nacelle as my previous approach to the air intakes makes it almost impossible to add the cowl flaps and also just looks unrealistic Done.
3- Remodel auxiliary nose landing gear doors (Blueprints don't show the actual design. Older mockup had a single door that opens forwards, unsure if that was maintained or not. The current design leads to the gear's scissors hitting the small doors when the nose gear is rotated) Done.
3- Remodel engine nacelle
4- Remodel wings
5- Fix discrepancies between model and listed dimensions
6- Add hinge brackets for the control surfaces and actuators for the flaps
7- Add trim tabs
8- Finish the aircraft's interior, including nacelle bomb bays
9- Model the auxiliary components of the engine, including oil tanks, oil cooler, air ducts and turbocharger
10- Texture mapping and painting
11- All the coding

If anyone has any questions regarding the aircraft or my modeling process/plans, let me know I'll do my best to answer them! There are a few things I myself am curious about, and so far only have theories about. For example, there are small flaps just aft of the main landing gear compartment on the nacelles. No one I've asked seems to know their purpose, and they're only present in the inboard nacelles. The theory I have formulated with some friends is that the flap opens when the landing gear is extended so that air going into the nacelle is directed outwards again instead of creating drag by hitting the back of the nacelle's interior. I also have yet to figure out where the oil cooler and exhaust stacks are in the aircraft, but I'll explain these problems (and my theories about them!) in a future post :)

The only reason I haven't provided specifications and whatnot is because I have to find out where I wrote the information down. Like I said, I've been working on it on and off, so I sometimes tend to forget where I've placed my references. Hope you guys like these progress shots!

Cheers,
-Matt
 
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Thanks for the kind words, guys

Interesting Matt, but what is it about this work that makes it 1:1?
Well, it's a flight simulator project, so it is 1:1 scale. The object (in Blender) measures the exact same as the plane. In hindsight seems like superfluous information, should I remove that from the title?
 
Way cool! What an immense project to undertake! I work with automotive CAD models all day, and can only marvel at the effort you are going to!
Thank you very much! Yeah, it'll be quite a long project, even with my "small" to-do list. Always glad to talk to someone with 3D modelling experience


There are a few things I myself am curious about, and so far only have theories about. For example, there are small flaps just aft of the main landing gear compartment on the nacelles. No one I've asked seems to know their purpose, and they're only present in the inboard nacelles. The theory I have formulated with some friends is that the flap opens when the landing gear is extended so that air going into the nacelle is directed outwards again instead of creating drag by hitting the back of the nacelle's interior. I also have yet to figure out where the oil cooler and exhaust stacks are in the aircraft, but I'll explain these problems (and my theories about them!) in a future post :)

Right, so I had some free time today, figured I'd explain those theories now

First off, the flap on the inboard nacelles. It's only on the inboards and is located pretty far back. Looking at pictures, it seems that's where the P5M Marlin's oil cooling flaps were, but again these don't appear in the outboard engines, so that would make little sense to me. I don't recall who suggested to me that they might be related to the landing gear, but so far I think that's accurate. I have yet to build a mechanism linking it to the actual gear. Here it is on the blueprints (circled in blue):
3 View Top 2.png


The other issue pertains to the general arrangement of the engine. As far as I know, no other aircraft used turbocharged R-2600s, so my references were limited. Martin themselves didn't seem to use turbochargers very often, but I'll try to see if they did have any such aircraft. I originally based it on the B-32's layout, since I know it quite well, but it's very hard to adapt as it uses two turbos per engine. Currently trying to base it off the B-24, as it's the plane that seems to have the most similar layout (two big intakes on the sides, one single turbo). Slight problem with that... I have no idea where the exhaust stacks are. The early variants and wooden mock-up had them on the right side of each engine, but this version does not contain that familiar-looking protrusion (probably too drag-inducing). Here's the suspected layout in the blueprints:
3 View Side.png

At first I considered that the exhaust stack might end at the first protrusion (since I can't see any opening flaps there and the aft protrusion has what look like cooling flaps), but then the location for the oil cooler intake makes no sense if that's the case and requires a curved tube. I think the layout I drew over the blueprints makes the most sense, with a small flat oil cooling flap (which I can't actually see) at the back of the first protrusion. I haven't seen many aircraft with opening flaps around the turbo though, and frankly that makes little sense to me. If anyone has any other theories, or has a lot of knowledge regarding turbocharged radials, please do contact me. The same goes for the small flap at the top of the nacelles.
 
I have Blender installed, but haven't used it yet. Can you draw parts to specific sizes like you can in SketchUp?
I think it depends on the shape, I know it can be done with a torus and a cylinder. Personally my approach is to scale things after "spawning" the shape. That being said, I will admit I'm not sure how much of this model I did measure, since I started it so long. What I had dimensions for, I used dimensions for. Some other objects I approximated dimensions based on the blueprints (I think I gave the astrodome a 10" radius because that matched the drawings relatively well and made more sense to me than scaling it to the drawing and making it like 10.2585" or something like that), but a lot of parts made earlier on were just approximated from the drawings, including most of the landing gear components. I'm also in no way an expert on Blender, I've just learned how to use it well enough for my own purposes.
 
Concerning engine cooling, flaps, gills, and vents for them - if there are turbos involved, there are also likely need to be intercooler inlets and outlets. Since the engines are approximately equal, guessing from the ductwork on a P-47 will not be too far off. Details will of course be different, but should be good for the scale of the amount of "stuff & space" needed. I can't see the allowances for them in the drawings provided. Or did I miss them?
 
Concerning engine cooling, flaps, gills, and vents for them - if there are turbos involved, there are also likely need to be intercooler inlets and outlets. Since the engines are approximately equal, guessing from the ductwork on a P-47 will not be too far off. Details will of course be different, but should be good for the scale of the amount of "stuff & space" needed. I can't see the allowances for them in the drawings provided. Or did I miss them?
I will see if I can adapt the P-47's layout and perhaps mix it a bit with the B-24's. As far as I understand it (and this is of course just guesswork), I think the two air intakes near the top of the engine are for the turbocharging system, whereas the bottom intake is solely for the oil cooler. Because the XB-33 was never fully built, there aren't blueprints that go into much detail regarding the engines, with these being the only ones that show them (other than one blueprint for an earlier proposal that had all air intakes combined into one very wide unit, seen below). I have found no measurements for any of the parts of the nacelle or cowling and mostly guesstimated the exterior based on the 3-views I've posted above.
nacelle.PNG

Whenever I next have free time, I'll try to draw up what I think the system might look like
 
Very slick looking work ! I wish I could learn how to use Blender. I tried downloading it but it wont run on my Windows POS pullstart computer. Time for an upgrade I guess.
 
Very slick looking work ! I wish I could learn how to use Blender. I tried downloading it but it wont run on my Windows POS pullstart computer. Time for an upgrade I guess.
Thank you, hoping to work more on it this week. I don't really remember Blender's requirements, but it ran reasonably well in my old PC which was what can't even really be considered a gaming laptop. It struggled to run most modern games in even low graphics. My best advice is just to look into a computer with more RAM, it makes a lot of difference
 

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