Scratch Built ''Carbon Copy Cub'' With free plans!

I always have wanted the E-Flite Carbon Cub ever since it came out, but I never had the $400 to buy one. I knew what I had to do: design my own! Spring break had just started so I had a lot of time on my hands. I had recently designed a De Havilland Beaver that flies very well, so I used a lot of the same techniques that I used on the Beaver to make the Cub  I started with figuring out what size I was going to make it. The motor that I had could swing a 13x6 on 4s, so I thought that would be a perfect motor for this plane. I decided to make the plane have a 60'' wingspan (about 20" less than the E-Flite Carbon Cub). .

As usual, I start the build by studying some pics of the plane I am trying to recreate. I also get the wingspan and length of the plane so I know the width to length ratio. In this case it was about 2:3; by that I mean the fusealage length is about 2/3rds the length of the wing.

Wings

After I knew what I wanted it to look like, I started on the wing. It ended up having a 60" wingspan and a 11.5'' chord including flaps and ailerons. The wingspan is the same as the Beaver, but the chord it a bit bigger on the Cub. The chord on the Beaver is only 10.75''. I gave the cub GIANT flaps and ailerons because I wanted to be able to fly very slow and do hovers while maintaining control. The flaps and ailerons are both 3.5'' wide. The flaps are 7.25'' long and the ailerons are 19'' long. In comparison to the Beaver, these are HUGE control surfaces!

The wing is 1.5" thick at the thickest part, about the same as the Beaver. I used one foam spar and a 30'' hard plastic spar. It seems plenty strong for general sport flying.

To get the curve on the wing tip, I cut a template and used razor blades to attach it to the wing tip. Then I just traced it and cut it out.

Fusealage/Tail

Now I started on the fuselage. I planed to make it 40'' long, same as the Beaver. The shape was basically the same as the Beaver, but I made it a little bit narrower. The front half is about 3.5'' wide, and then it tapers down to 2.25'' at the end.

I mounted the motor by sandwiching the mount in between  bbq skewers that I poked through the front of the fuselage.

When I finished the fuselage, I started on the tail section. For the horizontal stabilizer, I cut out one half and traced over it for the other half. I used a carbon fiber rod and a BBQ skewer to attach the two. I just free-handed the vertical stab.

I glued the servos near the rear of the plane so I could get the CG right without adding weight to the tail.

Decor/Wing mounting

After I got the tail section glued in, I started to try and recreate the color scheme with colored packing tape from Hobbyking. I actually ended up using my AMA number for the identification numbers on the tail and under the wing. I also covered the open wing tips with colored packing tape to clean it up a bit.

Than I just added some foam strips to the top of the fuselage. I also just used a piece of foam that I bent at an angle to use as the canopy. It is basically the same thing that I did with the Beaver.

I decided to mount the wings using rubber bands because it was the easiest way to do it and because that is how I did it on the Beaver and it seemes to work fine. I used a thick plastic material for the rubber bands to hook onto because it is farily light weight, but very strong. 

Landing Gear

Then it was time for the landing gear. I used the same landing gear concept that was used with the 200% FT Spitfire. I glued a piece of 1/8th inch plywood to the bottom where I wanted the gear to go, then I bent a piece of 5/16th inch steel rod into the shape of landing gear. Then I used these nifty little clamps to hold it on the bottom of the plane. This seems to work very well in terms of strength. Once it was attached, I added some foam wire cover type things to hide the wire. I also glued a tail wheel to the back because it looked cool.

Overall Review

The plane can fly very slow or moderately fast. It can hover, fly inverted, do aggressive snap rolls, and take off in about a foot if there is enough wind. The plane has tons of power and does not need a bigger motor. One thing that surprised me is how well it flew inverted. The beaver couldn't fly inverted for more than a few seconds. I think I messed up the look of the gear, and I think they should be farther forward, but it works for now. I also think that it might have flown a bit slower and better if I put undercamber on the wing tips. The only big drawback to this plane is that it cant handel the wind very well. 

Specs

Motor: BM3720A-KV650 Brushless Outrunner Motor

ESC: 40-50 amp

Prop: 13x6

Servos: 9 grams all around

Wing Span: 60''

Wing chord: 11.5''

Length: 40''

Battery: 4s 2200 to 3000

Weight with 4s 3000: 58 OZ

Weight without battery: 47 OZ

Wing loading: about 12.47 OZ per square foot.

Radio used: Tactic TTX650

If you have any questions, leave a comment and I will try to anwser your questions.

Plans

I couldn't get the tail section to look right on Sketchup, so you could either use the tail feathers I did, or design your own. Feel free to either scale the plans up or down to make a mini cub or a extra giant one! You also may need to scale the plans for your printer. 

Finished Plane Pics

Flight Video

Sorry about the video, there is more sky than plane.  My dad isn't that great at filming:)

Thanks to Fred Provost for the sweet article name!