FTFC20 SBD Dauntless-5 designed by Fidget

[Fidget]

I'm designing a foam board SBD Dauntless from balsa plans for this year's design challenge.
I'll be basing it on a design from Outerzone: https://outerzone.co.uk/plan_details.asp?ID=5185

My interest stems from some family history that I wrote about here: https://forum.flitetest.com/index.p...brance-naval-aircraft-training-history.58794/
My great uncle crashed and was lost in an SBD Dauntless in 1942. Based on the inventory of the time it was an SBD-4 or SBD-5. I found more models of an SBD-5 so I'm running with that.

The original plan is for an 88" wingspan plane. I want to drop it to 66", but practically speaking I should just cut it in half and do 44". That will fit an FT powerpack, and fit much better in my workshop. I might change my mind again as I design it. I really want to model the split flaps and the swing-arm bomb drop, and I'll need space for servos for those.

 

[Fidget]

Reserved for plans

 

[cdfigueredo]

Good project, SBD Dauntless is a great looking airplane. What materials do you plan to use?

 

[Fidget]

Nice proyect, SBD Dauntless is a great looking plane. What materials do u think to use?

Thanks! I'm planning to use mostly FT foam board. I've been watching the P47 build video and am pondering using the more formers & skin style.

 

[cdfigueredo]

Thanks! I'm planning to use mostly FT foam board. I've been watching the P47 build video and am pondering using the more formers & skin style.

That sounds good. Will be following the thread.

 

[rockyboy]

Awesome! Thanks for sharing your historical connection to the plane too!

 

[Fidget]

Today's work:
Found a 1/48 Revell model at my local hobby shop that I bought. The SBD dropped one large bomb that it carried under the fuselage. The dove at 70 degrees downward to hit the targeted ship. If you just dropped the bomb it would hit the prop, so it had a swing arm that basically flung the bottom away from the plane and out under the prop. I'd been thinking of how to make the ends of that arm, but the Revell model just has straight ends on the arm and grooves in the bomb itself. I think that's what I'll do. Then I just need a fork mounted to a servo arm.

I've been interested in this plane for a few months, so I got a couple of books about it for my birthday a while back. I probably won't model nearly the detail they show, but they're interesting and give me something to look at while I think.

Also mocked up a symmetrical wing with both flaps and dive brakes (top right image). The shape and scale are very crude. I cut the paper off of the control surface about 1/2 to 3/4" from the edge and then sanded away some foam so that they meet at a nice angle. I smeared some hot glue on the surface, sort of like we do "hot glue hinges". At least on 1" wide section it's not too weak. I'll probably smear them with clear Gorilla Glue in the end.

The SBD deployed the downward flaps and upward dive flaps in a dive to keep it from over-speeding. They had holes in them so that some air reached the elevator in the rear, so that they could pull up out of the dive. I'm thinking I'll only make the holes if I get my Rascal CNC built and working.

 

[jfaleo1]

Holes could be easily made with a sharpened piece of brass or copper tube that could also be slightly heated up by a heat gun. Press and turn steadily and on the paper on the back side take it easy. Or put the tube in a drill and do the same for small diameter holes. I used to do this even on balsa. Just be sure you back up the piece well.

 

[Fidget]

Holes could be easily made with a sharpened piece of brass or copper tube that could also be slightly heated up by a heat gun. Press and turn steadily and on the paper on the back side take it easy. Or put the tube in a drill and do the same for small diameter holes. I used to do this even on balsa. Just be sure you back up the piece well.

Thanks! I've heard of that but never tried it. I was just scaling the plans, and the holes will be right at 1/4" diameter, so it should be easy enough to find an appropriate tube to try it with.

 

[jfaleo1]

Thanks! I've heard of that but never tried it. I was just scaling the plans, and the holes will be right at 1/4" diameter, so it should be easy enough to find an appropriate tube to try it with.

Remember to sharpen the tube I have used sandpaper or a file for this. easy way is chuck up the tube and spin it against the sandpaper.
Good luck.

 

[rockyboy]

I had no idea about the pivot arm for dropping bombs during a dive run - really incredible how steep the dive was!

 

[Fidget]

I had no idea about the pivot arm for dropping bombs during a dive run - really incredible how steep the dive was!

With the guy in the back trying to fend off other aircraft with his machine gun and remember to not shoot off the vertical stab.

 

[dougbradbury]

I would love to build a foam Dauntless. 10 years ago a started a balsa build that I have never finished: https://www.rcgroups.com/forums/showthread.php?515431-Douglass-Dauntless-at-30-for-5-ch Pat Trittle was selling a short kit at that time: http://www.patscustom-models.com/dougdaunt.htm. That also might be some good inspiration for your design. It's a size that I think would fly nicely on the B pack. Please share your design and I would love to build along with you! Are you trying to build working dive flaps? The perforated dive flaps on the dauntless are so cool, but I can't think of a simple way to pull it off in foam.

 

[Fidget]

@dougbradbury thanks for the links!
Yes, I'm planning on dive flaps. I'm going to try the holes with the technique that @jfaleo1 mentioned above. I want to stick with foamboard, so we'll see how the strength holds up. I've considered doing less holes, but I'd want to come up with a pattern that still looks good.

 

[willsonman]

I modified a Windrider foamy dauntless years ago to have split flaps. The weight from the added servo and hardware was a bit much for it. After I removed all flap hardware and fixed them, she was a stellar belly lander. While a full-house Dauntless is always nice, keep in mind that the price is always weight.

My current ESM Dauntless is a peach to fly. I even added a scale-moving trapeze for the bomb drop. Bigger does fly better... and it handles the weight better too

With regard to flap strength, I have been able to successfully utilize my 3D printer for various applications. Of note in relation to this project is how I used a print of scale tail gear on my Corsair. I ended up needing to beef up strength. To do this, I used thin CA and 12K carbon tow. I can see how this may be applicable here. Creating a printed flap and then on the inside, lay down the tow and soak in the thin CA to make it more rigid. Keep in mind that any flap (top or bottom) is creating turbulent air and will undergo a lot of stress due to the drag when deployed. The holes will add to this.

Should you go with foam for the flaps, you could also inset carbon rod or even balsa sticks (maybe bamboo skewers) into score cuts with foam safe CA. Again, you are adding weight so be smart in whatever you choose to do.

 

[Slowpoke51]

I'm designing a foam board SBD Dauntless from balsa plans for this year's design challenge.
I'll be basing it on a design from Outerzone: https://outerzone.co.uk/plan_details.asp?ID=5185

My interest stems from some family history that I wrote about here: https://forum.flitetest.com/index.p...brance-naval-aircraft-training-history.58794/
My great uncle crashed and was lost in an SBD Dauntless in 1942. Based on the inventory of the time it was an SBD-4 or SBD-5. I found more models of an SBD-5 so I'm running with that.

The original plan is for an 88" wingspan plane. I want to drop it to 66", but practically speaking I should just cut it in half and do 44". That will fit an FT powerpack, and fit much better in my workshop. I might change my mind again as I design it. I really want to model the split flaps and the swing-arm bomb drop, and I'll need space for servos for those.

I'm designing a foam board SBD Dauntless from balsa plans for this year's design challenge.
I'll be basing it on a design from Outerzone: https://outerzone.co.uk/plan_details.asp?ID=5185

My interest stems from some family history that I wrote about here: https://forum.flitetest.com/index.p...brance-naval-aircraft-training-history.58794/
My great uncle crashed and was lost in an SBD Dauntless in 1942. Based on the inventory of the time it was an SBD-4 or SBD-5. I found more models of an SBD-5 so I'm running with that.

The original plan is for an 88" wingspan plane. I want to drop it to 66", but practically speaking I should just cut it in half and do 44". That will fit an FT powerpack, and fit much better in my workshop. I might change my mind again as I design it. I really want to model the split flaps and the swing-arm bomb drop, and I'll need space for servos for those.

 

[Slowpoke51]

I had the same idea the other day, after watching part of the giant p-47 build. I went over to my blueprints cabinet and pulled out the SBD.
Plans are the 100" Nick Ziroli Jr. that I never started in Balsa. I'll be building it out of Dollar Tree foam and Lite-Ply, 3 piece wing, and retracts. Will be using some of John's new Master series techniques, building it in sections. Best of luck to you on yours!

 

[Fidget]

I had the same idea the other day, after watching part of the giant p-47 build. I went over to my blueprints cabinet and pulled out the SBD.
Plans are the 100" Nick Ziroli Jr. that I never started in Balsa. I'll be building it out of Dollar Tree foam and Lite-Ply, 3 piece wing, and retracts. Will be using some of John's new Master series techniques, building it in sections. Best of luck to you on yours!

Have fun! I'd love to see pics as you go.

 

[Fidget]

@willsonman thanks for your advice! I was just listening about carbon tow on the Parkflyer Podcast yesterday.

I'm hoping to get closer to my want-to-include list this year (landing gear, flaps, bomb drop) than I have with previous years' competitions. We'll see how the fall shapes up!

 

[Fidget]

Tried @jfaleo1's suggestion. Cut off about 2" of aluminum 1/4" tube and chucked it in my drill. Sharpened it with a file and tried it on foamboard. The image on the left is the "top" side and on the right is the "back" side. It makes a much softer edge through the back paper. It really needs another piece of waste foamboard behind it so it will pop on through the back piece of paper.



I'm thinking that for the dive flaps I'll cut the holes with this method, then peel the back paper off and sand it so that it tapers at the back. Then cut an slit in an S between all of the holes. Then slide some 3k carbon tow in the slot and fill with either foam safe CA or clear Gorilla Glue.