Fuselage Boom Assembly Begins

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Now that parts inventory and preparation have been completed the fuselage boom assembly can commence. We started by locating all of the parts necessary for assembly.  The bulk heads were fastened to the boom sides as outlined in the instructions.  This was followed by attaching the top and bottom skins to the boom.  We ran out of cleco fasteners in short order and had to wait a couple of days for more to arrive.  The additional cleco’s allowed us to fasten all of the parts that comprise the fuselage boom although we still did not have enough to fill every hole that would need to be riveted.  The next step will be to fasten all remaining 1/8″ holes and then double check the fitment prior to starting the riveting process.  We don’t want to have to drill-out any incorrectly placed rivets.

Here we begin the sub-assembly of the Boom Sides and Internal Stiffeners and the Rear Wing Spar Carry Thru.
Ethan sets the first official rivet in place.
Noah sets the second official rivet into place.
The first and second rivets are officially set and signed.
Forward section of Fuselage Boom is held together with cleco fasteners.
Ready to mate the aft section with the forward section.
All hands on deck as the assembly grows.
Only a few more cleco fasteners left before we run out and need to reorder.
Inside view of the Fuselage Boom.
After a long day of hard work you come in the next day only to find the project draped in Christmas lights. They couldn't even wait until after Thanksgiving... The shiny, reflective surface of the 2024 aluminum really make the lights pop.

Time lapse of Fuselage Boom assembly.

We Have Parts

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Our first shipment of parts has finally arrived from Rainbow Aviation in Corning, CA.  The parts were delayed due to a slip-up on the part of UPS–not sure how you ‘lose’ an 8 ft. long wooden crate.  This initial shipment includes all of the parts necessary to build the Fuselage Boom, Vertical and Horizontal Stabilizers, Elevator, and Rudder.

The first step in the process was to check for any damage and then inventory all of the parts.  It took us almost 3 hours to go through all the part numbers.

The next step involved preparing all of the parts for assembly.  This basically required that all edges and holes of the aluminum skins be deburred (removing all sharp edges left over from the machining process).  This took 3 to 4 students about 3 meeting periods to complete.

The crate UPS lost for a week, ready to be opened.
Here we begin the inventorying process. All parts are numbered and need to be cross-referenced with our order sheet.

Custom 3D Printed Drill Tooling

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The Forward Spar requires that 2 holes be drilled near each end.  After using the tube template to locate and center punch were the holes are to be drilled, we need to make sure that the holes are parallel to one another and that we are drilling normal to the tube at that location.  To ensure that the two 1/4″ holes were aligned with one another we designed and printed two clamps that the tube would tightly slide into.  Then we mounted the clamps to a scrap piece of 3/4″ plywood. The drilling jig would now rest on the drill press table and guarantee square and aligned holes.

CAD rendering of the drilling jigs.
The Forward Spar mounted within the drilling fixture.
Fixture mounted to the drill press platform.
The Forward Spar ready for drilling.

Wing Box Fabrication

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The Wing Box fabrication starts with the assembly of the welding fixture.  Using deck screws we built-up the tooling to accept the 4130 steel tubing.
The boom mounts are the first parts that need to be bolted on to the fixture.  Unfortunately at the time of wing box mock-up our shop was not quite set-up for welding.  That meant we could not weld the boom mount washers to the 1.125″ tube.  In the mean time we designed and 3D printed temporary inserts to act as the washer.  This would allow us to align and bolt the boom mounts to the fixture.  At that point we could proceed with the coping and fitment.

Brian Carpenter @ Rainbow Aviation has refined the coping process using templates generated using his CAD files.  He has produced a good video that describes the process.  Brilliant!

Wing box tooling sides.
WIng box base tooling with alignment pins.
Wing box tooling ready to accept tubing.
3D printed temporary inserts act as washers until the real washers can be welded. They allow for the boom mount tubing to be bolted to the jig so that fitment of the other tubes could proceed.
Close-up of the temporary 3D printed insert holding the tube in place for initial tube fitment.
The teplating procedure gives a near perfect fit.
Getting close to tack welding everything in position.

Cutting 4130 Steel Washers On Waterjet

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Using the OMAX Waterjet Machine we can easily cut the boom mount washers from 1/8″ 4130 steel.  The waterjet doesn’t even break a sweat as it accurately pierces through the material.  We will be using this machine to cut all of the required flat stock parts.  We also use this machine to fabricate some of our competitive robots and a myriad of other projects.

Here's what the layout looks like on OMAX Make after everything has been pathed.
Clamping down the material prior to the cut.
Washers cut with tabs to prevent them from falling through the slats.
Finished product.
We also cut the wing box tooling spacers using the waterjet.

Cutting Welding Fixtures

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While waiting for the 4130 steel to arrive*, we started by cutting the tooling fixtures with our ShopBot CNC router.  Using the dxf files from the builders database and 3/4″ plywood, we cut the 4 full sheets of ply which will provide all the tooling required to weld-up the fuselage frame.

*Living in Hawaii does have its disadvantages.  Most of the parts/supplies that we require cannot be sourced locally.  Long lead times will slow progress and shipping costs add up quickly.  The price of paradise…
Our machinists hard at work.
Cutting the parts that will make up the fuselage tooling jig.
The pathed file in VCarve.

Time lapse video of the CNC operation.

Visit To Rainbow Aviation

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Our project officially launched with a visit to Rainbow Aviation  in Corning, CA where Brian, Carol, and Jasen gave a tour of their facility and provided details of the EMG-6 motor glider.  Following the visit we decided that the EMG-6 would be the perfect platform for our project.  It’s a solid design that is configurable and the fact that all of the design files are open-source will make it convenient for us to configure the propulsion system as desired.

Rainbow Aviation Facility in Corning, CA.
"Sparky" - One of the EMG-6 prototypes.
Prototype to be fitted with the Polini 250 engine.