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Jul 22, 2011, 12:04 PM
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Build Log

40" AT-502 Airtractor

Been busy getting the new 40" span Airtractor drawn up and am now getting around to the build. The idea is for a simple, light weight 4 ch. Park Flyer, using the E-Flite Park 250 for power. The build is simple and straight forward, so lets get started.

The build begins with the wing. It's done up using a 2 spar egg-crate style design that goes together really fast.

Construction begins with gluing the main and rear spars together with their ply dihedral braces. The front spar uses a brace on both sides, the rear spar has only one.
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Jul 22, 2011, 12:06 PM
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On To the Center Section

The center section is built first. The spars are pinned to the plans and the ribs added and glued in place. The leading and trailing edges are addednext, followed by the hold down bolt plates.
Jul 22, 2011, 12:13 PM
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The Outer Panels

The C-section is unpinned from the plan and the spar assembly rocked over onto the left panel. The assembly is dry fitted and tack glued with thin Cya. The aileron is built in place on the wing assembly.

The RH panel is built the same way, with a block placed uner the LH panel to support the wing while the other side is assembled.

The completed assembly is lifted from the board and the joints all glued with thing Cya, then the assembly is rough sanded, the ailerons removed, and then sanded to final shape. The aileron hinges are then cut in to complete the assembly.
Jul 22, 2011, 12:15 PM
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Building the Tail Section

Nothing out of the ordinary here. The parts are built directly over the plans, sanded to shape and the hinges cut in.
Jul 22, 2011, 12:18 PM
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Mmmm Love the Airtractor. Had the e* 802. Think you will really like the way it flies.

Jul 22, 2011, 12:19 PM
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Building the Fuselage

Assembly begins with the fuselage side frames. The landing gear is bent to shape, and mount assembly is built up around it. The sides are joined begining at the landing gear assembly. The side frames are pinned over the top-bottom assembly plan and squared up using triangles or machinists squares.
Jul 22, 2011, 12:22 PM
Veni, Vidi, Napi
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Cool Pat!

Hmmm... wonder if I could hack it a bit and turn it into a 401-B using one of Sparky's radials?

What can I say? I like round engines.

Does this mean you're on a ag plane kick? I hope.

Jul 22, 2011, 12:22 PM
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Adding the Remaining Formers and Stringers

The assembly is removed from the board and the side frames scored and cracked at the bends, then the remaining formers are aligned and glued in place followed by the stringers to complete the basic assembly.
Jul 22, 2011, 12:27 PM
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Fitting the Wing to the Fuselage and Building Up the Belly Pan.

The wing is taped into the wing saddle and the dowel holes drilled into the wing using a home-made drill bit made from music wire to insure proper alignment. The wing was removed, the dowels glued into the wing, then the hold down bolt holes were drilled and tapped.

The belly pan formers and stringers were added next, followed by the balsa fill to fair in the bolt holes.
Jul 22, 2011, 12:34 PM
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Mounting the Servo, Control System and Motor/ESC

With all the sub-assemblies completed and the basic shaping and sanding finished it was time to mount up the running gear. The aileron servos are glued in place with silicone caulk. The rudder and elevator servos are mounted on balsa rails. The elevator pushrod tube was run in, followed by the rudder pull/pull cables.

The firewall is set up for the E-Flight 250, so that was just a simple matter of screwing the motor in place.
Jul 22, 2011, 12:37 PM
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Framing is Just About Finished

And with that, framing is about wrapped up. I still need to add a few minor details, work out the canopy frame, and carve the cowl plug and shee'll be ready to cover.

Jul 22, 2011, 01:43 PM
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In! Wow Pat, you just started this build and here you're almost finished!

Jul 22, 2011, 03:56 PM
I eat glue
I wondered if you would ever wander over to an Air Tractor. Ordering plans for a 72" version.
Jul 27, 2011, 10:34 AM
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Thanks Pat for getting this project going! It has been a pleasure working with you, and I look forward to your posts on the remainder of this little Air Tractor! bob
Last edited by Ag Bug Killer; Jul 27, 2011 at 10:35 AM. Reason: forgot to identify
Jul 27, 2011, 11:19 AM
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Originally Posted by Ag Bug Killer
Thanks Pat for getting this project going! It has been a pleasure working with you, and I look forward to your posts on the remainder of this little Air Tractor! bob
Ag, Good to see you step in. Please feel free to post up pics of your build here too....

Meanwhile, the cowl plug is on it's way to Sparky, and the drawings are about done for the canopy frame. The windows are all flat plates, so the frame for it is really not a complicated assembly at all. Will get started building it real soon.


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