Building Aero 3D Day 21: Ribs Glued & Scarf Joints

Today started by reinforcing the scarf joints, seen in the featured image above, using gussets which in this case is made out of wood (filler I believe). The pieces are cut to the width of the sides they are going on (1/4” in this case) and a length that goes a bit past the scarf joint on each end. You can see the glued pieces, using medium CA in the featured image above. In the image at the bottom you can see where weights were left on the spars to keep them flat.

Once that was done we moved on to the wing. Using the big ruler to help keep a straight edge we propped up the trailing edge along it… we started with the ruler at the end closest to us in the picture below (right) and pinned some blocks to support it from the other side.

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Building Aero 3D Day 20: Scarf Joints

Scarf Joint Marked

Yesterday I learned how to make a scarf joint and then proceeded to make four of them. For this model the wing is one piece; however, the spars are not long enough in a single piece so need to make them out of two pieces. Since need one for top and bottom need two of each. The main spars are made out of 1/2” x 1/4” balsa and the other two out of 1/4” x 1/4” balsa.

The rule of thumb (apparently with full scall aircraft too) is a ratio of 12:1. That is for every 1 unit of thickness you need 12 units of overlapping length. I may not have explained that well so here are the numbers for my pieces.

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Building Aero 3D Day 19: Hinging Prep & Wing Beginnings

Stabilizer, Fin & Elevator Posing

Sunday afternoon Peter came over and got caught up on my progress. Since we were done on the fuselage for now we put it aside for safe keeping and focused on the tail control surfaces to start with.

For the rudder, stabilizer and two elevators I prepped them for hinging. At this point I also brought out my new toy (thanks Steph for the Christmas gift 🙂 ), the vise you see in the left image below.

While everything was still pinned to the table I marked two hinge line locations for hinging the rudder to the fin (vertical stabilizer). The elevator hinges were previously marked. Next we clamped the rudder, fin, stabilizer and each elevator into the vise one at a time using some scrap balsa sheeting to protect the pieces from the vise clamps.

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Building Aero 3D Day 18: Fin, Rudder & Fuselage

Wing Saddle Sanding

Today I made some more progress on my Aero 3D. I started with the gluing portion which focused on the fin and rudder. The result seen in the image below.

I had everything laid out from last session so I started with the fin and glued all the pieces together. I actually missed the cross-brace somehow as I moved pieces to glue so I ended coming back at the end of everything to put it into place (not the most efficient usage of glue). For the bottom of the fin I glued some filler between the piece I previously broke (the notch for the cross brace in the bottom piece) and the trailing edge.

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Building Aero 3D Day 17: Stabilizer, Rudder & Fin Oh My!

Stabilizer Ribs Glued & Hinge Locations Marked

Wednesday Peter came over and we got to work on the aircraft. I replaced the defunct far right rib of the horizontal stabilizer (image above) with a new one. We then marked a center line on the trailing egdge and rib so that when we placed the rib back we knew its positioning.

We then got to work gluing all the ribs into place as well as the two end pieces. Once that was done, and ribs were pinned in place, placement for the hinges were marked across the elevator and trailing edge of the stabilizer. We also glued some 1/2” balsa blocks behind the elevators leading edge where the hinges are going to be for added support. You can see these, along with the glued ribs, in the featured image at the top. There will be 6 hinges total, 3 on each side.

Next we moved back to the rudder & fin.

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Building Aero 3D Day 16: Stabilizer Ribs & Fuselage

Stabilizer Ribs Cut

Yesterday evening I did some work on my aircraft for about an hour after I got home, prior to getting supper.

I started by cutting out the ribs for the stabilizer… I guess technically I should be calling this the horizontal stabilizer as what I’ve been calling the fin is probably more properly known as the vertical stabilizer :).

Once I had the six ribs cut out of 14” x 14” balsa to length I trial fitted them and ended up cutting three filler pieces for the three left ribs. In the picture above, you can see the filler pieces laying in the openings between ribs. The lengths of the ribs from left to right in the featured image are 27/16”, 21516”, 33/8”, 33/8”, 3”, and 21/2”. Chop that up to being human as in an ideal world they first and second set of 3 (left and right ribs of the stab) would be equal length.

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Building Aero 3D Day 15: Gluing Stab, Rudder & Touch-ups

Carving Out Wing Cradle

Yesterday Peter came over and looked at what I had laid out for the fin & rudder so far.

We then moved back to the stabilizer and got the trailing edge and ‘intermediary’ piece cut to size. Starting with the trailing edge we did the following:

  • Cut the end off at a 45 degree angle using a mitre box
  • Lined it up in place and marked with a pencil on the inside edge where it goes to
  • Cut it at a 45 degree angle, a little oversized
  • We were happing with the fit on the left side (image below) so sanded the right side repeatedly until happy with the overall fit

Once the fit was as we wanted we moved on to the inside piece, going between the trailing edge and S1. This involved:

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Building Aero 3D Day 14: Rudder & Fin Started

Today I started finding the pieces that make up the rudder and fin of the aircraft, pinning them in place. I started with R1 (the top of the rudder) and R2, which I will say is a cross brace of the rudder making up the bottom of the front half that hangs over the top of the fin and connects back to the trailing edge of the rudder. I lightly sanded these two pieces and then pinned R1 into place making sure the left and right sides were equal distance from the edge of the workbench. The image at the bottom can be used for reference and how I left things pinned at the end of this session.

Using the fixed R1 piece and the angle of the R2 piece I lined up a piece of 14” x 14” balsa stringer and used the left hand sides of R1 & R2 to get the angle correct along with making sure the two middle slots lined up appropriately so the 12” x 14” balsa was verticle (used a triangle to help ensure right angles at the top). Having these pieces pinned in place I was able to cut the 12” x 14” balsa to length, 212” and the 14” x 14” balsa stringer that angles between the leading edge and R2 to lengh, 234”.

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Building Aero 3D Day 13: Gluing Elevator Frame & Stab Leading Edge

Elevators & Stab Leading Edge Glued

Yesterday Peter & I worked on the tail again. We are using carpenters glue, as another member of the club (Marc) mentioned how he has been using it and carpenters glue has been working well for him.

We glued all the pieces of the two elevators together using the carpenters glue. As previously mentioned due to some loose fitting pieces filler was utilized to’fill’ the gaps.

We started with the leading edge of the stabilizer and glued the two S2 pieces (that make up the leading edge) to the bottom of S1 and pinned the pieces in place.

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Building Aero 3D Day 12: Elevator Framework Pinned

Elevator Framework

Yesterday I did some work on the elevators by myself. This involved getting the perimeter of the right elevator pinned in place and then measuring the length for the ‘cross-braces’ making up the internal structure of the elevators and getting them cut and pinned in place out of 14” x 14” balsa stringers.

The length of the stringers from small to large are 218”, 234” and 314”.

I was surprised by the looseness of the fit. It’s like they didn’t take into account some light sanding of the laser cut joints where glue would be applied.