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

by Captain T | March 24, 2015 | (16) Posted in Projects

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.

Blurry pic of the wing's insides.

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.

Before

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!

 

 

COMMENTS

alibopo on March 28, 2015
That plane looked very sweet in the air - beautiful slow-speed performance. :) For my personal flying style, I'd be tempted to push the CG forward a little - it looked slightly tail heavy to me. But you '3D-style' flyers have different flying setups, and it wasn't out of control or anything like that, so that's just my opinion. It's a nice uncomplicated build design and it did what you wanted, so that's a win-win-win on price, performance and style! Well done.
P.S. If you're camera has a viewfinder, tell your dad to keep both eyes open. That way he can keep an eye on the 'bigger' picture as he's concentrating on the shot. If it's a camera with just a flat screen, those are always harder to track. (I hide my duff 'empty sky' moments by editing them out!)
Cheers :)
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Captain T on March 28, 2015
Thanks! I usually try to keep things simple when I design planes. My dad was using a smart phone to film so there was no view finder, he just needs practice:) I already edited most of the sky parts out. There was a 1:5 plane to sky ratio before I edited it. I think I brought it down to 1:2 ish:)
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HarleyRev on March 28, 2015
very nice build ! I like the look of the cub and have seen one fly, they fly well. I may build one someday too. Thanks for sharing.
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Adam Buildtip on March 28, 2015
great build,wery cool,can somebody tell me how thick is the foam that Flite Test is using???
Keep up the good work:)))))
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Captain T on March 28, 2015
it is 1/4'' thick. It comes in 20x30 sheets.
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dharkless on March 29, 2015
Actual thickness is 3/16"
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1959cutter on March 28, 2015
where can i find those nifty clamps!? and what are they originaly used for?
great cub design!
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Captain T on March 28, 2015
Well, they dont have a specific name, just 1/4 zinc rubber coated clamps, but I got mine at lowes at the hard to find hardware section.
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flysky on March 29, 2015
great job!

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dharkless on March 29, 2015
Very nice design and build. I see the quality improve with each project. Nice window details and nice smooth cuts on the tail feathers.
Very impressive slow speed performance.
Shoot me an e-mail. I have a couple of suggestions that I don't want to post here. dhark69@gmail.com.
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debay777 on March 30, 2015
Seems like the electronics are a bit over powered. I'm thinking a 800-900 KV park 480 swinging a 10" prop will give you the juice you need at a much lower amperage and thus shorter flight time. Excellent design. I plan on scaling it up to maybe 80". I may keep it at 60". Not sure yet.
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debay777 on March 30, 2015
Found my specs. My balsa cub came in at about 1 lb with only servos installed. between the motor and battery and ESC might as well add another 3/4 to 1 pound. The Park 480 is 960 kv and swings a 10x5 prop. at WOT she draws 17 amps. performance wise she takes off in 10' or less if I goose it. I tried a rolling take off at half throttle and she refused to stay down. Oh and that was with a 2200 3 cell. She wasnt fast mind you, but she had low end power for STOL and slow speed recovery.

Im tabling my other build ideas for now. Im building this next.
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debay777 on March 30, 2015
Hey I watched your video again. I agree, looks tail heavy or you need some down elevator dial in. In my limited cub experience, they seem to want to climb with throttle and require quite a bit of mechanical trim to keep them going level. Did you set the motor pointing down and to the right? that can help with nose up tendencies. Simple things like moving the servos forward of CG can make a huge difference.
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Captain T on March 30, 2015
It is a wee bit tail heavy, but I like they way it flies with a aft CG because it can hover better and it is more ''snappy''. I don't have any right or down thrust, but that might be nice.
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HilldaFlyer on April 2, 2015
Great plane! I'm in the process of making a Beaver, so this was really great to see. One thing that I didn't catch, where is the hatch/opening for installing the flight battery? Is it installed under the wing? Thanks.
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Captain T on April 2, 2015
The hatch is on the top of the plane. It is on the front section of the fuse. It is a piece of foam I bent at an angle that just folds up and down in the front. It goes more in detail in my extra modle.
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Captain T on April 2, 2015
http://flitetest.com/articles/50-foam-board-extra
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Deuxchevaux on April 2, 2015
Great job, Captain T

The proof is in the pudding: it flies great and you do too! Thanks for sharing! -malcolm
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Captain T on April 2, 2015
Thanks! That means a lot!
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Flight Risk on April 8, 2015
This Carbon Copy rocks!
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Phantom_flyer on April 12, 2015
I am mixing the beaver and the copy cub together
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Captain T on April 13, 2015
Sounds awesome!
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Jake3dpilot on July 22, 2016
Hi Toby its Jake we flew together at flitefest I flew the crack beaver what do you like more your copy cub or your beaver
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Captain T on July 22, 2016
Hey Jake! The beaver is incapable of any 3d, but it is a nice STOL fun flyer. The cub could do some mild 3d, but I never got enough incidence on the wing so it needed the flaps on to fly well. My favorite plane is still the sledge tho. I'm making one with a red tail p-51 scheme now! Question, does you bush wacker want to snap out of things on you? On snap to hovers and any upright harrier it wants to stall out and spin. It has a really nice inverted harrier tho. Thanks!
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Jake3dpilot on July 23, 2016
My bushwhacker does want to snap on high alpha stuff, my water proof one got destroyed but I made I knew one. It flies amazing.
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Jake3dpilot on July 23, 2016
Hi Toby if you go on YouTube and look up 93" laser Thomas arnold that's me
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Scratch Built ''Carbon Copy Cub'' With free plans!