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Jul 13, 2017, 03:50 AM
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Decathlon Quick Build!!!

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Span- 31"
Length- 22"
Flying weight- 4.5oz with BL180, 5oz w/ BL250
4 Channel
Power- park180 slow flyer, park250 for 3D performance
Lipo- 2S 280mAh 30c provides me 5 mins of 3D w/ the BL250
prop- GWS 6x3
ESC- 10A (BL250) 6A (BL180)

Performance- No stabilizer
Ground handling extremely stable. My easiest plane to land EVER. One wheel drive n' go's are definitely called for.
Flies it's self, until you disturb it.
Extremely light, and slow when you want it, but 3D capable aerobatics. Prop hangs, knife edges, inverted, a little slower on the AIL rolls, however.
Hey! There's Room for a pirate! I mean .. pilot! (que the 3d printed jack sparrow)

Lately, I've really wanted something aerobatic and yet slow flying for those calm, dusky, summer nights at the park. Don't have a ton of $ to spend on airplanes this year. I liked the idea of realistic lighting, and scale features such as clear windows, and a nice "manufactured" quality to it.. ALL while being amazingly cheap, fast and easy to slap together. Great stability in the air, and on the ground is a must for me. (no fish tailing or tail spinning allowed for my "touch n' go" addiction). I pictured a model that could be easy to repair and include simple part replacement, all from home with a few magic machines that you can build yourself, or buy relatively cheap. Wouldn't it just be nice to LAUGH when you crash a scale model, knowing that as long as the electronics survived, you could be back up in no time and for basically no dollars? In this thread I will cover step by step exactly how I was able to get parts to look factory made. I'll provide full downloadable PLANS, FILES, and SETTINGS for FREE so you can make your own. A parts list and materials list will be posted. If you use these, please post some pics!? I will build another airplane (red and white) and show you step by step how to get er' done the easy way! (photos and video series), which include some pretty dang neat little hacks you can do at home. Here's a few of them-

*Make your own custom EVA tires with detailed rims and tread. (walmart under $5 EVA sheet)
*The "Juiciest Aileron" method you've ever seen.. maybe... I liked it.
*Vacuum forming PERFECT cowls, windshields, Leading edges, wing tips, wheel pants.. etc (Easier than you think and it's INSTANT compared to 3d printing, and much better surface quality. )
*My way of Heat Shaping depron sheets with ease, or similar to depron sheets. (Leading edges, control surfaces, and wing struts.)
*3D Print all of your own hardware, including landing gear struts, rims, control horns.. and even props! (I've made it work!)
*Near weightless LED lighting, using SMD Led's with no light board (plug straight into Rx, or bum off servo lead) If you want flashing, you'll need a board.
*Nice sticky backed markings from your inkjet printer.

If you would like to build the airplane but don't have access to the machines, you can still build it by hand cutting the patterns from the files. You can improvise the hardware using classic build techniques. If you want a "shortkit" package with all Vac Formed parts, Laser cut Parts, and 3D printed parts, I will gladly ship them to you. Just shoot me a PM with your shipping address.

This airplane has been seriously PURE JOY, to build and fly. I've put several packs thru it already and still going strong. There are some changes and a couple small upgrades I'd like to add during the build log. So be aware that the parts list may change a bit during the build log. I will try not to post any files that will change later.

I hope you guys enjoy this airplane, lemme know if you do and I'll design another one. Like maybe a "Porter".. "Cubby".. or a Beaver-Fever??? Maybe a Twin of some type?


RC Decathlon made with desktop CNC machines at home! (3 min 46 sec)
Last edited by Scalejet757; Jul 17, 2017 at 06:43 PM.
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Jul 13, 2017, 05:52 AM
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File download

Here is some footage with the BL250 upgrade. Build Files are listed below. (Still a few more to add) The files are subject to change during the build. I have been updating everything to the best of my knowledge for the new build. I am beginning the build of V2 immediately, and will be posting every step along the way. Please post pics of your Citabrithon! enjoy!

Citabrithlon (1 min 51 sec)
Last edited by Scalejet757; Aug 26, 2017 at 02:00 AM.
Jul 13, 2017, 10:44 AM
Registered User
cbalgra's Avatar

Let me be the first to say, outstanding job on the Citabrithon!

Very clean and well engineered design. Marvelous CAD, 3D printing and vacuum forming.

The Citabrithon flies very realistically with the Park 180, and quite "spritefully" with the 250.

Looking forward to more of the build of #2. Especially interested in your aileron hinging technique.

Jul 13, 2017, 02:37 PM
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Thanks Brad! I've got lots to share.. The ailerons and tires are my fav. I used to dread them.. now I can't wait to hook em' up!
Jul 13, 2017, 02:40 PM
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cbalgra's Avatar
Waiting patiently to learn new things.
Jul 13, 2017, 02:55 PM
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Source your own Tires and Gear

You can source your own tires by cutting thin "tire slices" from an EVA sheet (under $5 at walmart) and stack them together with CA or spray 77. When finished they appear to have tread lines. If you use a laser, be aware that the fumes can be pretty harmful to yourself and animals. Open the window, wear a mask, and close off your area to traffic. I 3D print rims to fit into the center of the tire snugly with CA. Of course you can use other methods if you don't have a 3D printer. Bottle caps, metal tubing, plastic tubing, etc.

For the struts, I just 3d print them from PLA with 3 outer shells and at about 40% infill. They are strong and work well. If they break, print another set! The axle is just music wire pushed into the designed hole on the strut with CA. You can also print it as more of a pilot hole and heat the wire before pushing it in, which will allow the plastic to melt around the wire. Much more strength in that method, but I haven't found it something I have to do. Use wheel collars, wire bend, or 3d print push-on collars to keep the tires on the axle. The struts were also designed with the tires slightly angled inward for stability. This worked great, I had zero tail spin or fish tailing while ground handling.

On the green decathlon, I vacuum formed the wheel pants, but I decided that I would like to now 3D print them and use them as a 2 in 1 system; instead of wheel collars, the inside of the wheel pant will have a slot for the axle, and connect to the strut. I will document in the next build.
Jul 13, 2017, 03:23 PM
flyin' fool
goldguy's Avatar
Wow, what an amazing project.

Especially considering that I'm all about EPP and hot melt.
Jul 13, 2017, 05:24 PM
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Gonzo007's Avatar
Great looking plane

What watt laser head are you using?

Jul 14, 2017, 12:41 AM
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Thanks Colin! It's a 3500mw diode. It's a little weak, but gets the job done. Only cuts materials that are not white or reflective. The laser in the video is a 60 watt co2 laser that I had to use to cut the white depron. Looking to put one of those suckers in my shop in place of the diode. Can't wait!

Gold guy- yes, the balsa can be subbed with EPP.. and I did use hot melt! infact I think the whole airplane can be subbed with dollar tree foam, or EPP. The tolerances need adjusting is all obviously the plastic is kinda hard to sub with foam..
Jul 16, 2017, 02:40 PM
Senile Member
Lnagel's Avatar
Fantastic Broc,
I don't have a CNC cutter but I do have a 3D printer. Looking forward to the plans and stl files.

Jul 16, 2017, 03:07 PM
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Originally Posted by Lnagel
Fantastic Broc,
I don't have a CNC cutter but I do have a 3D printer. Looking forward to the plans and stl files.

Larry! Comin' right up! Worked on the mods to the plans/files late into the evening yesterday. Just making some final improvements before posting for you.
Having a 3d printer will get you pretty far here. You can make your own molds and vac former, and hand cut the foam parts with patterns.

G'day, Broc
Jul 16, 2017, 09:24 PM
Registered User
rajazo's Avatar
impressive work... it flies amazing.
you showed than combining foam, balsa and 3d printed part are a excellent way to go

can you tell more about the vacum former? I was thinking to use 3d printed mold to make some parts but I have doubt about the temperature to fomer the plastic and the PLA resistence.

hope to see plans soon and STL files
Jul 16, 2017, 11:00 PM
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Rajazo- thanks kindly! I have figured out the secret to using both PLA and ABS for vac forming, and the parts come out stunning to say the least. I will show exactly how when I get to that step.
Last edited by Scalejet757; Jul 17, 2017 at 06:36 PM.
Jul 17, 2017, 06:39 PM
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Files posted above (second post). Build of V2 to begin shortly
Jul 19, 2017, 06:23 AM
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Vacuum Forming Secrets

There's a hundred and one DIY vac forming tutorials out there.. but most haven't talked much about the most important step! I discovered a few things over the years that have made this a profound and valuable technique for building model airplanes. It's SO much faster than 3D printing, much better surface for painting, and it's lighter in most cases. The other thing I like is the impact resistance. A lot of times, you can just pop the dents out after a mishap. So one of the seemingly dumb components that makes this DIY so much better, is the Silver Ducktape used to tape the plastic sheet to the frame. I stumbled upon this by accident years ago.. went to get some ducktape to see if it would hold. Bought some silver instead cuz I thought it looked nicer.. and bang. No more clamping, no more bolts with screws and washers, AND.. you can re use your strips over and over again.

Vac Forming "The Right Way" at Home! (5 min 1 sec)

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