50" Scratch Built Foam Board Extra

by Captain T | November 27, 2014 | (6) Posted in Projects

      I have always wanted a balsa wood 3d machine, but they cost a lot of money and are not the slightest bit durable. I am 14 so getting the money to buy a balsa kit would be hard, so I made a DTFB Extra type thing. I really love the FT 3D, so I tried to basically make a giant FT 3D. I freehanded most of the plane, so everything is not exact, but it looks alright.

After noticing some wing flex on the first flight, I decided to add a carbon fiber arrow shaft to the wing to prevent the wings from folding. It gave the wings a huge amount of strength. You can hold it by the wing tip with a battery installed and the wings don't even flex! I am very impressed with how rigid the wings are given that there is only a 25" arrow shaft and a single foam spar inside. The wing span is a wee bit under 50'' and it is 40'' long.

One of the funny things about this plane is that is has a small amount of accidental anhedral. I don't really notice anything bad when flying right side up, but it is a little more stable inverted which makes it really fun to fly inverted.

The electronics are from a old Dynam SU-26M that was not in the best shape. I replaced all the servos with HobbyKing 9 gram servos because the old servos stopped working. I used the BBQ skewer technique with the push rods because they may or may not be paper clips:) I am using a 2650 mah 4 cell 50c Nano Tech. The 2650 will fly it for around 10 mins. I am also using a 13x4 prop on a genaric 650kv motor which gives it tons of power!

The motor is mounted with a simple piece of 1/4 inch plywood. I simply cut a 1/4 inch slot in the nose with a slight amount of left thrust angle. Then, I slid the plywood with the motor already attached into the slot and added lots of hot glue.I also reinforced the nose with lots of popsicle sticks because the motor is so huge. I didn't want the motor to pull out of the foam while flying. The canopy is just a flat piece of foam with a tape hinge. There are 2 strips of velcro that hold it down in flight.

I put red packing tape and black star stickers on the top because it looked really cool. I also put black stripes on the bottom to help with orientation.

 The video isn't the best quality, but it gets the point across.

COMMENTS

Noobi1951 on November 28, 2014
Looks like you built a winner! Great job, and good flying. You mention the motor being huge, but I missed what the motor is. What is your wing span? Length? All in all, a great job, and who needs balsa when you can do that.
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Captain T on November 28, 2014
It is a generic motor, but I know it has a 650 kv rating. It is swinging a 13x4 prop with a 4s and is pulling a little over 40 amps. It has tons of power. It can go vertical at half throttle. The wing span is about 50'' and it is 40" long. I will add that to the article. Thanks!
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81zapper on November 28, 2014
Super job heck of a pilot also love designing and building my own too even though Im a newbie having a blast and your so young so much time to build and fly enjoy

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Captain T on November 28, 2014
Thanks man, I am on Thanksgiving break now so I have tons of time to build and fly for the next week!
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Jake3dpilot on July 27, 2016
Nice article captain
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50" Scratch Built Foam Board Extra