Air tractor AT 402 B Build and cad design

Flying Farm Kid

Active member
I live on a farm in NW Ohio and we see air tractors flying around us and spraying the fields all the time. In my opinion they look awesome and I have always wanted to build one. This thread will be about me designing and building an air tractor. I am designing it mainly in onshape in 2d and 3d, I plan to make plans for this so it will be easier for me to build it and so all of you guys out there can to! And because I hope to build an erc cutter so I can get a cleaner build.
Design constraints.
-Around a 60 in wing span, or power pack C size
- Ailerons elevator rudder throttle and flaps
-be relatively simple to build
-scalable
-working spray nozzle's, maybe if it fits (;
-looks like the real thing, obviously
- 3d printed landing gear holders to stop the foam from tearing
3d printed scale details exhaust, spray bar, tank, etc

This is my first planed scratch build and first time making plans.
If you are wondering why I chose the AT 402 B its because it has the most 2d style plans for it.
Any tips or ticks are welcome and hopefully by the end of this we will have an air tractor!
download (1).jpg

Air-Tractor_402B_social.jpg
 

ColoFlyer

Active member
I am not sure if you have seen the FT Duster, but this may give you a place to start, or some design ideas. Or you could build one if these.
I have built this plane and if fly's amazing.
 

Flying Farm Kid

Active member
Progress I have almost finished the fuselage outer skin. I am using @Whit Armstrong build series for fusion 360. It is very helpful to have guide lines to
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know what to do even though I am doing it in onshape hope you like it this is design number 3 of it.
 

Flying Farm Kid

Active member
Ok here is the next update. I have finished most of the internal structure in the fuelash and the wings, there are only the little fiddely bits left to do. Like the servo holes on the fuse and the back of the cabin, aswell as some other small details like the landing gear.
 

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FoamyDM

Building Fool-Flying Noob
Ok here is the next update. I have finished most of the internal structure in the fuelash and the wings, there are only the little fiddely bits left to do. Like the servo holes on the fuse and the back of the cabin, aswell as some other small details like the landing gear.
Internal Structure... that's what I keep forgetting! This project is looking great, keep at it.
 

Flying Farm Kid

Active member
Here is the next update finished landing gear and wheels. The wheels will be 3d printed wile the strut its self will be bent aluminum. Now I just have to figure out how to attach it to the airplane. I think I made my nose to long though so I might have to change that. Have a Great Christmas to.
 

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Flyin Okie

New member
This may be slightly off-topic, but having seen one of their sister aircraft at work this summer, I thought I’d share.
We were delayed by a wildfire in the Columbia River gorge and saw the AT-802F Fire Boss hard at it.
 

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Flying Farm Kid

Active member
How do you make the plane work with foamboard in onshape? I would like to design a kitfox. I've already gotten used to onshape, but am not super advanced. Thanks.
I just use a 4mm thickness for everything you could be more advanced and set a material as foamboard and change each piece but that can be a lot to manage. I am going to use Pepakura Viewer to unwrap everything I have yet to do that though so I don't know how it will work. My best advice is to not be to particular it will all end up in 2d so the exact thickness all around does not matter to much as long as it is close. It is only a foamboard airplane after all. Hope this was helpful and a happy new year!