Lovely work so far!
SBD Dauntless, from scratch
- Thread starter Witold Jaworski
- Start date
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
- Thread starter
- #42
Witold Jaworski
Airman 1st Class
@SANCER: Thank you! Answering your questions: well, in fact I earned my Msc. Eng. in aeronautics in 1994. However, I choose different professional path and became an IT consultant... All the programs I use in my work on this Dauntless model are the free, Open Source software: 2D drawings: GIMP (www.gimp.org), Inkscape (www.inkscape.org), 3D: Blender (www.blender.org). So they are affordable for all!
@Wurger: Thank you!
@Gnomey: Thank you!
OK, let's continue:
In the previous post I have modeled the aileron bay in the SBD Dauntless wing. However, it was one of the cases when I followed my intuition and the mathematical precision of the computer models instead checking how this detail looks in the real airplane. So let's do it now. I have reviewed many photos. The figure below shows the one which is the most useful (made by my friend in 2014 in one of the air museums):
We can see here that the flaps are attached (via a very long hinge) to a reinforced structure which resembles a spar. It ends at the first aileron hinge. On the other hand, the aileron is mounted on three "point" hinges which protrude from the ribs. Thus the curved sheet metal that closes the aileron bay has much lighter structure, because it is merely a cover. It is riveted to the ribs and other wing skin panels. The "sharp corner" at the upper edge of the aileron bay is obtained by a fragment of the upper wing skin that overlaps (by about half of inch) the bent, rounded edge of the internal wall.
I recreated in my mesh the auxiliary spar along the flaps and the fragment of the wing skin that overlaps the upper edge of the aileron bay:
I will model the bent upper edge of the internal wall later, during the detailing phase. The lightening holes in the spar will not be modeled. For such less important openings I will use transparency textures.
At the beginning of the previous post I cut off the wing trailing edge. Now I split it into two objects: the aileron and the flaps. Then I started to work on adapting the aileron mesh. First I simplified its topology: I slid its upper longitudinal edge forward, where the curved leading edge begins (Figure a), below). I do not need its bottom counterpart, so it will disappear. In the effect the aileron cross section resembles a triangle, as in the real airplane. (Such simplifications of the theoretical trailing edge geometry were common in this aircraft generation).
To form the curved shape of the aileron leading edge I extruded vertically from its bottom edge two face rows (Figure b), above). Then I closed the remaining gap with another row of faces.
After small adjustments of their vertices at the wing tip I obtained the rounded shape of the aileron leading edge:
Then I did some further adjustments, checking if the gap between the aileron and the wing is wide enough (0.2") for the whole aileron rotation range (from -10⁰ to +17⁰). You can see the result in the figure below:
However, comparing this result with the photos, I discovered that I fitted it too tightly! What's more, I also noticed differences in the shapes of the aileron tip and its bay between various restored aircraft:
The outer wing panels were the same in all the SBD versions (at least their external details — see this post) — so I cannot explain these differences as the differences between various aircraft versions. Well, it seems that one of these restored aircraft was modified afterward. But which one?
To determine which case is wrong, you have to look at the archival photos:
In the picture of a factory-fresh SBD-1 you can see that the tip of the aileron was curved. Nevertheless, I had to widen the gap between the aileron and the wing tip, reproducing the case I can see on the archival photo:
In this source *.blend file you can check all details of the model presented in this post. In the next post I will recreate the flaps.
@Wurger: Thank you!
@Gnomey: Thank you!
OK, let's continue:
In the previous post I have modeled the aileron bay in the SBD Dauntless wing. However, it was one of the cases when I followed my intuition and the mathematical precision of the computer models instead checking how this detail looks in the real airplane. So let's do it now. I have reviewed many photos. The figure below shows the one which is the most useful (made by my friend in 2014 in one of the air museums):
We can see here that the flaps are attached (via a very long hinge) to a reinforced structure which resembles a spar. It ends at the first aileron hinge. On the other hand, the aileron is mounted on three "point" hinges which protrude from the ribs. Thus the curved sheet metal that closes the aileron bay has much lighter structure, because it is merely a cover. It is riveted to the ribs and other wing skin panels. The "sharp corner" at the upper edge of the aileron bay is obtained by a fragment of the upper wing skin that overlaps (by about half of inch) the bent, rounded edge of the internal wall.
I recreated in my mesh the auxiliary spar along the flaps and the fragment of the wing skin that overlaps the upper edge of the aileron bay:
I will model the bent upper edge of the internal wall later, during the detailing phase. The lightening holes in the spar will not be modeled. For such less important openings I will use transparency textures.
At the beginning of the previous post I cut off the wing trailing edge. Now I split it into two objects: the aileron and the flaps. Then I started to work on adapting the aileron mesh. First I simplified its topology: I slid its upper longitudinal edge forward, where the curved leading edge begins (Figure a), below). I do not need its bottom counterpart, so it will disappear. In the effect the aileron cross section resembles a triangle, as in the real airplane. (Such simplifications of the theoretical trailing edge geometry were common in this aircraft generation).
To form the curved shape of the aileron leading edge I extruded vertically from its bottom edge two face rows (Figure b), above). Then I closed the remaining gap with another row of faces.
After small adjustments of their vertices at the wing tip I obtained the rounded shape of the aileron leading edge:
Then I did some further adjustments, checking if the gap between the aileron and the wing is wide enough (0.2") for the whole aileron rotation range (from -10⁰ to +17⁰). You can see the result in the figure below:
However, comparing this result with the photos, I discovered that I fitted it too tightly! What's more, I also noticed differences in the shapes of the aileron tip and its bay between various restored aircraft:
The outer wing panels were the same in all the SBD versions (at least their external details — see this post) — so I cannot explain these differences as the differences between various aircraft versions. Well, it seems that one of these restored aircraft was modified afterward. But which one?
To determine which case is wrong, you have to look at the archival photos:
In the picture of a factory-fresh SBD-1 you can see that the tip of the aileron was curved. Nevertheless, I had to widen the gap between the aileron and the wing tip, reproducing the case I can see on the archival photo:
In this source *.blend file you can check all details of the model presented in this post. In the next post I will recreate the flaps.
Last edited:
Nicely done so far!
A4K
Brigadier General
Fantastic research mate..!!
If you need Dauntless decals, I've got theses going spare - 1:48 Monogram SBD (top), and 1:32 Matchbox.
If you need Dauntless decals, I've got theses going spare - 1:48 Monogram SBD (top), and 1:32 Matchbox.
Lucky13
Forum Mascot
Amazing! 
- Thread starter
- #47
Witold Jaworski
Airman 1st Class
Wurger, Gnomey, Lucky13 - Thank you for following this thread!
A4K - Thank you very much! However, I will not be able to use your stickers! Reading your message I realized that I have to write an off-topic post, explaining what kind of models I build:
Many years ago I was making a 1:24 models from scratch (the motto from CommanderBounds' footer: "Build what YOU want, the way YOU want to, and above all have fun" is good expression what I wanted . You can learn more here). In 2006 I decided to try a completely new branch of our hobby: computer models. Once you have accepted the fact that you cannot touch such a model, there are tremendous advantages:
- you can recreate the original airplane as precisely as you want - your patience and available time is the only limit!;
- you can always update your model when you find new references and you find an error in your work;
- you can build any airplane you want, in any camouflage and markings - just to find a good reference!
For the traditional "plastic" modelers, the computer models combined with the 3D printers open another option: why do we have to wait for a kit manufacturer? Instead of being consumers, let's become "prosumers"! Of course, to learn all aspects of this new technology you have to start by making small details you are missing in your models, then larger elements... Who knows, you can ultimately make a complete plastic kit in this way!
I specialized in another field: visualizations. Usually I try to recreate something that really happened (for me this is a kind of the ultimate test: if the model looks like a real thing in the real environment, then I obtained the effect I want). Going a little bit off topic, I will show it on an example. Here is my previous model, the P-40B:
(Click here to see larger version of this image)
You can also apply an alternate camouflage: in this case it is an AVG fighter, standing on the Kweilin airfield:
(Click here to see larger version of this image)
What's more, you can make dynamic, in-flight scenes like this one:
(Click here to see larger version of this image)
I titled this one "Unexpected end of Saturday's party". These two P-40B from 47th PS are taking off from provisional Haleiva airstrip (Hawaii, Oahu island) on 7th December 1941. The 47th PS avoided the direct attack, on that Sunday. A few days earlier, they were relocated for the gunnery training to provisional Haleiva airstrip, at the north of Oahu island. Two pilots from this unit – George Welch and Kenneth Taylor – managed to return to the airfield and get airborne. (All flying staff had left this field base for the weekend, and Japanese fighters could "hunt" this day even the cars on the roads!). Both survived this day, destroying some Val diving bombers. They fly two times, that day. On the second time, they were caught by the Vals just over the Wheeler Field runway. They downed the Taylor's machine, and its pilot got hurt. Welch shot down the Japanese airplane that attacked Taylor, and flew again over the port.
I build my models using the free, Open Source software: Bleder, GIMP, Inkscape, which is available for all. What's more, we can share our computer models - so do I, here. They are accompanied by a free "getting started" booklet, which explains how to install these software and its basic usage. Of course, a much thicker guide that describes everything is also available. So I encourage everybody who would like to try! It is a great fun!
A4K - Thank you very much! However, I will not be able to use your stickers! Reading your message I realized that I have to write an off-topic post, explaining what kind of models I build:
Many years ago I was making a 1:24 models from scratch (the motto from CommanderBounds' footer: "Build what YOU want, the way YOU want to, and above all have fun" is good expression what I wanted . You can learn more here). In 2006 I decided to try a completely new branch of our hobby: computer models. Once you have accepted the fact that you cannot touch such a model, there are tremendous advantages:
- you can recreate the original airplane as precisely as you want - your patience and available time is the only limit!;
- you can always update your model when you find new references and you find an error in your work;
- you can build any airplane you want, in any camouflage and markings - just to find a good reference!
For the traditional "plastic" modelers, the computer models combined with the 3D printers open another option: why do we have to wait for a kit manufacturer? Instead of being consumers, let's become "prosumers"! Of course, to learn all aspects of this new technology you have to start by making small details you are missing in your models, then larger elements... Who knows, you can ultimately make a complete plastic kit in this way!
I specialized in another field: visualizations. Usually I try to recreate something that really happened (for me this is a kind of the ultimate test: if the model looks like a real thing in the real environment, then I obtained the effect I want). Going a little bit off topic, I will show it on an example. Here is my previous model, the P-40B:
You can also apply an alternate camouflage: in this case it is an AVG fighter, standing on the Kweilin airfield:
What's more, you can make dynamic, in-flight scenes like this one:
I titled this one "Unexpected end of Saturday's party". These two P-40B from 47th PS are taking off from provisional Haleiva airstrip (Hawaii, Oahu island) on 7th December 1941. The 47th PS avoided the direct attack, on that Sunday. A few days earlier, they were relocated for the gunnery training to provisional Haleiva airstrip, at the north of Oahu island. Two pilots from this unit – George Welch and Kenneth Taylor – managed to return to the airfield and get airborne. (All flying staff had left this field base for the weekend, and Japanese fighters could "hunt" this day even the cars on the roads!). Both survived this day, destroying some Val diving bombers. They fly two times, that day. On the second time, they were caught by the Vals just over the Wheeler Field runway. They downed the Taylor's machine, and its pilot got hurt. Welch shot down the Japanese airplane that attacked Taylor, and flew again over the port.
I build my models using the free, Open Source software: Bleder, GIMP, Inkscape, which is available for all. What's more, we can share our computer models - so do I, here. They are accompanied by a free "getting started" booklet, which explains how to install these software and its basic usage. Of course, a much thicker guide that describes everything is also available. So I encourage everybody who would like to try! It is a great fun!
Last edited:
... and nothing more to add. Your work is very useful for modellers. Please keep heading... 
Świetna robota i bardzo pomocna dla wszystkich, zwłaszcza dla tych , którzy mają problem z widzeniem przestrzennym. ... A jest ich trochę. Proszę mi wierzyć.
A4K
Brigadier General
With Wojtek!!
Dzieki, yes, I did think you meant plastic (or resin!) modelmaking... I'm still old school!
Your P-40s look fantastic... will follow this tutorial with alot of interest. Like Wojtek said, though completely different mediums, it will be very useful information for when I build my 1:72 Hasegawa SBD-4.
Cheers!
Evan
Dzieki, yes, I did think you meant plastic (or resin!) modelmaking... I'm still old school!
Your P-40s look fantastic... will follow this tutorial with alot of interest. Like Wojtek said, though completely different mediums, it will be very useful information for when I build my 1:72 Hasegawa SBD-4.
Cheers!
Evan
Last edited:
Lovely work!
- Thread starter
- #52
Witold Jaworski
Airman 1st Class
Wurger, A4K, Rogi, Gnomey : thank you!
Currently I am leaving on vacation (away from the computer for two weeks). I will describe further progress of my work on the SBD Daunless on August 29th.
Currently I am leaving on vacation (away from the computer for two weeks). I will describe further progress of my work on the SBD Daunless on August 29th.
SANCER
Senior Master Sergeant
Good trip and see you upon your return. 8)
Saludos cordiales
Luis Carlos
SANCER
Saludos cordiales
Luis Carlos
SANCER
A4K
Brigadier General
With Wojtek and Luis - have a good trip mate, look forward to your progress when you come back.
CommanderBounds
Airman 1st Class
Agreed! Can I use one of those shots of the P40 as my desktop background because those look terrific!
- Thread starter
- #57
Witold Jaworski
Airman 1st Class
Wurger, SANCER, A4K, CommanderBounds: thank you! I have just returned from the trip
@CommanderBounds: of course, it is a great honor for me if you choose one of these images as your desktop background. Let me know if you need its dedicated version, having proportions and size adapted for your screen (1920x1080px?).
For example, I already made another shot of this airplane for my friend (the picture on the left, click these images to see the full-size versions):
This is CAF P-8186, assigned to William N. Reed from 3rd squadron of the AVG. It had rather chaotic painting scheme, including the forgotten RAF roundels. I would title these pictures "Yangtze Sharks" (the background is a real aerial photo of the Yangtze river). I will glady adapt the two other pictures below for the screen proportions/size, if somebody of you would like to have them as a screen background!
@CommanderBounds: of course, it is a great honor for me if you choose one of these images as your desktop background. Let me know if you need its dedicated version, having proportions and size adapted for your screen (1920x1080px?).
For example, I already made another shot of this airplane for my friend (the picture on the left, click these images to see the full-size versions):
This is CAF P-8186, assigned to William N. Reed from 3rd squadron of the AVG. It had rather chaotic painting scheme, including the forgotten RAF roundels. I would title these pictures "Yangtze Sharks" (the background is a real aerial photo of the Yangtze river). I will glady adapt the two other pictures below for the screen proportions/size, if somebody of you would like to have them as a screen background!
Last edited:
- Thread starter
- #59
Witold Jaworski
Airman 1st Class
Thanks, Wurger! Let's continue:
Perforated split wing flaps were the hallmark of the SBD Dauntless. Their inner side was reinforced by the "grid" made of stringers and ribs. Because these flaps were often wide open — during landing or in dives — I have to recreate their internal structure. In this and the next post I will describe how I did it.
All the SBD flaps had fixed chord (they were made from perforated sheet metal of rhomboidal shape). After studying many photos I assume that all their ribs have the same size and shape — also the parts attached to the trapezoidal, outer wing section. It seems that Douglas factories built all five flaps of the SBD in the same way, using unified components. The flaps for the external wing panels had to be twisted a little during riveting — most probably on appropriate mounting pads. The trailing edge of the upper flap is the trailing edge of the whole wing. It was a thin wedge, profiled from a sheet metal and riveted to the flap skin:
(Similar wedge is riveted to the upper skin of the center wing — see the picture above). The chordwise contour of these flaps looks flat on the photos. In fact there is only a small difference (less than 0.2 inches) between the theoretical contours of the wing airfoil and a straight line on the area around the trailing edge. I think that for the designers such a technological simplification was not a big deal — they had already made a more serious modification by perforating the flaps.
I started building the SBD flaps by creating their upper and lower planes. (I created them by simplification of the mesh fragment that I previously cut off from the wing). I used the Solidify modifier to give them thickness of a sheet metal. (I used this modifier for all parts which I will create in this post). Then I added the wedge (another object) along their trailing edge:
I started this wedge as a single contour, which I extruded along the whole span of the flap. Because of the trapezoidal shape of this wing, I had to twist a little the outer end of this wedge, fitting it better to the upper flap. Then I shortened the trailing edge of the bottom flap, fitting it into the wedge when it is closed.
When it was done, I added the main "spar" of the flap (in fact it was a U-shaped stringer). I did it in the same way as I created the trailing edge: shaping the profile, then extruding it lengthwise:
Once extruded, I had to rotate this object and twist its end, lying its outer edges on the inner surface of the flap skin. To facilitate this process I assigned this object a contrast, red color.
While fitting this spar, I discovered that the twisted, four-vertex face of the flap skin has small elevation along its diagonal (as in picture above). It is not something "real" — just an effect of the internal decomposition of all quads into triangles made by Blender.
To eliminate this artificial effect I had to divide this sigle, large face into several smaller pieces:
It minimized the influence of Blender internal "triangulation" and allowed me to properly fit the stringer to the flap. As you can see in the picture above, the end profile of this spar is twisted, following the twist of the flap skin.
After the first stringer I created in a similar way two other reinforcements on the flap edges:
As you can see, I used two clones of the rib contour. (I needed them to determine slopes of the front and rear reinforcements in the side view — as in picture above).
When the flap lengthwise reinforcements are in place, I can add the ribs:
All the internal ribs are clones of a single mesh. The external ribs have the same contour, but each of them has its own mesh (because they do not have the cutout for the central spar, as the internal ribs). These flap ribs have quite complex shape, but I managed to keep their mesh quite simple. It was possible, because a part of this complexity (the sheet metal thickness, rounded edges) is created by the Solidify and Bevel modifiers.
When the ribs were in place, I added the last stringer. It was a "L"-shaped beam:
Modeling internal structures of the flap forced me to carefully measure anew all of its details, especially the width and location of its spars. In the effect you can see that my wing drawings are not as precise as you could expect:
In this source *.blend file you can check all details of the model presented in this post. In the next post I will continue my work — this time on the upper flap.
Perforated split wing flaps were the hallmark of the SBD Dauntless. Their inner side was reinforced by the "grid" made of stringers and ribs. Because these flaps were often wide open — during landing or in dives — I have to recreate their internal structure. In this and the next post I will describe how I did it.
All the SBD flaps had fixed chord (they were made from perforated sheet metal of rhomboidal shape). After studying many photos I assume that all their ribs have the same size and shape — also the parts attached to the trapezoidal, outer wing section. It seems that Douglas factories built all five flaps of the SBD in the same way, using unified components. The flaps for the external wing panels had to be twisted a little during riveting — most probably on appropriate mounting pads. The trailing edge of the upper flap is the trailing edge of the whole wing. It was a thin wedge, profiled from a sheet metal and riveted to the flap skin:
(Similar wedge is riveted to the upper skin of the center wing — see the picture above). The chordwise contour of these flaps looks flat on the photos. In fact there is only a small difference (less than 0.2 inches) between the theoretical contours of the wing airfoil and a straight line on the area around the trailing edge. I think that for the designers such a technological simplification was not a big deal — they had already made a more serious modification by perforating the flaps.
I started building the SBD flaps by creating their upper and lower planes. (I created them by simplification of the mesh fragment that I previously cut off from the wing). I used the Solidify modifier to give them thickness of a sheet metal. (I used this modifier for all parts which I will create in this post). Then I added the wedge (another object) along their trailing edge:
I started this wedge as a single contour, which I extruded along the whole span of the flap. Because of the trapezoidal shape of this wing, I had to twist a little the outer end of this wedge, fitting it better to the upper flap. Then I shortened the trailing edge of the bottom flap, fitting it into the wedge when it is closed.
When it was done, I added the main "spar" of the flap (in fact it was a U-shaped stringer). I did it in the same way as I created the trailing edge: shaping the profile, then extruding it lengthwise:
Once extruded, I had to rotate this object and twist its end, lying its outer edges on the inner surface of the flap skin. To facilitate this process I assigned this object a contrast, red color.
While fitting this spar, I discovered that the twisted, four-vertex face of the flap skin has small elevation along its diagonal (as in picture above). It is not something "real" — just an effect of the internal decomposition of all quads into triangles made by Blender.
To eliminate this artificial effect I had to divide this sigle, large face into several smaller pieces:
It minimized the influence of Blender internal "triangulation" and allowed me to properly fit the stringer to the flap. As you can see in the picture above, the end profile of this spar is twisted, following the twist of the flap skin.
After the first stringer I created in a similar way two other reinforcements on the flap edges:
As you can see, I used two clones of the rib contour. (I needed them to determine slopes of the front and rear reinforcements in the side view — as in picture above).
When the flap lengthwise reinforcements are in place, I can add the ribs:
All the internal ribs are clones of a single mesh. The external ribs have the same contour, but each of them has its own mesh (because they do not have the cutout for the central spar, as the internal ribs). These flap ribs have quite complex shape, but I managed to keep their mesh quite simple. It was possible, because a part of this complexity (the sheet metal thickness, rounded edges) is created by the Solidify and Bevel modifiers.
When the ribs were in place, I added the last stringer. It was a "L"-shaped beam:
Modeling internal structures of the flap forced me to carefully measure anew all of its details, especially the width and location of its spars. In the effect you can see that my wing drawings are not as precise as you could expect:
In this source *.blend file you can check all details of the model presented in this post. In the next post I will continue my work — this time on the upper flap.
Last edited:
Users who are viewing this thread
Similar threads
