So, finishing the thought from my previous post the epiphany I had while trying to sleep was that during my last session with Peter the plan was to glue the trailing edge (W-TE-1, 1/4” x 3/8“, ) on while the hinge support blocks were still exposed. This allowed me to use them as anchors for clamping.
To follow through with this plan I checked how the leading edge piece was fitting on the back of the wing and did some touch up sanding to remove excess glue around the scarf joint. Also, went over everything using the balsa pieces I cut to ensure the balsa sheeting would lay flat, sanding where I needed to.
Once I was happy with the fit I poured up some wood glue and lathered it on the back of the wing where the piece is going to go. I then placed W-TE-2 (Trailing Edge) on and clamped, from left to right, along the back of the wing. I started this holding the wing up, balancing on the leading edge, until I made enough progress.
Once I had it all clamped down I went back to the beginning and ensured the trailing edge was flush with the top (which is actually the bottom in the picture) trailing edge (W-TE-2). As I worked my way down I discovered it was off a bit. So I loosened the clamps and re-adjusted and then reapplied the clamp.
Once that was done I went back over the entire thing until I was satisfied that the trailing edge (W-TE-1) was, to the best of my knowledge, properly in place.
I then left everything as seen in the pictures to let it dry.
Sunday, I couldn’t take not building anymore so I went rogue and got back to work on my aircraft. I started prepping the back of the wing so I could add W-TE-1.
First I was thinking about the trailing edge and looked at making the W-TE-2 pieces. For this I took a piece of 3/32“, 4” wide, balsa sheeting and cut it in half, measuring 2 inches along the sheeting. Unfortunately my cut wasn’t perfect as I learn to do things on my own, the sheet shifted and thus not a perfectly cut in half piece. This is where a bandsaw would come in handy :). When I go to put it in place I will see if it will still work or not.
Fixing my overzealous sanding involved using some shavings from where I cut the back down. I sanded pieces to fit into gouged out places. I then used wood glue to glue them in place, pinned on each end and clamped in the middle.
You can see a close-up of this in the featured image above and the general locations for the 4 touch-ups in the image below.
That wrapped up this session. I didn’t want to do to much as I was still uncertain exactly how best to approach the rest; however, check out my next post coming as I did have an “epiphany” that night while sleeping. 🙂
Wednesday, Peter came over and we made some more progress. Could only do a little bit as the trailing edge is required to continue.
First, using a forstner drill bit, I drilled a hole into the top center of the wing. Peter held a piece of ply behind to help prevent the balsa sheeting from splintering while I drilled. This hole is where the servo leads (likely a Y extension) will come up through and into the fuselage to connect with the receiver.
Once that was done we determined the length of the trailing edge, which needs to be made out of two pieces, insuring some excess. Allowing for 3 inches of overlap I cut the excess off of one piece to make it more manageable to work with and then:
Marked 3 inches from each end of the scarf
Drew a line along the diagonal of the wider side of one
Marked side to be sanded
Determined how the diagonal line needed to be drawn on the other and which side marked to
Ensure pieces would fit together, one on top of the other
Sanded down to the line testing the fit along the way
Using 30 minute epoxy I glued the two pieces together
Placed a pin in each end and clamped to dry
You can see the final scarf joint clamped together and left to dry in the image below.
Due to Covid-19 and social distancing I’m not sure when our next session is going to be.
Sunday, Peter & I did some more work along the trailing edge of the wing. I started by continuing where we left off cutting down the trailing edge. I took a few more passes with the utility knife and then moved on to using a sanding block to get it flush with the back tip of the ribs. I did my best to ensure I didn’t nick the ribs in the process, but unfortunately I’m not perfect and you can see some light patches where I brushed against them with the sand paper.
Yesterday Peter came over and we got to looking at the ‘instructions’ again. It appears the top and bottom sheets go right to the trailing edge along the ribs and then a cap goes right along the back.
Because of that I started cutting off the excess WKA/WKB that has been hanging around incrementally using my utility knife. You can see the trailing edge in the featured image above and notice that the process isn’t completed. We kept a piece of 3/32” balsa up against the excess edge as a guide. Once I reached that point we stopped the process this session. Once we are confident in the configuration, Peter is going to bring W-TE-1 ( 1/4”x 3/8” balsa piece) so we can determine how everything is going to come together before proceeding with the trailing edge.
That didn’t stop us from making more progress as we moved on to the bottom of the wing. Peter cut out some more ‘sheet glue supports‘ from balsa and marked the center lines. I then used medium CA to glue them under the leading edge sheet between each rib.
I then cut out a piece of 3/32”, 4″ wide”, balsa similar to the peice on the top of the wing in length and curves. Using wood glue I applied it to the glue supports, ribs (previously marked how far back) and along lines Peter marked on the bottom of the sheet that’ll make contact with the ribs.
The sheet was pinned in place and weights placed on top while the glue dries. This wrapped up another session!
Wednesday we completed Step 4 of the wing instructions (minus cutting flush the trailing edge). Peter brought all the W-SH-5’s & W-SH-4’s he cut at home out of 3/32” balsa a bit longer then required.
I lined one of the pieces up on a rib, marked how much needed to be sanded off one end and then sanded them down to fit. Once I had them all sanded I marked the center of the rib on the top and bottom sheets so that while gluing we had a reference point to center the ‘rib caps’ on the top of the ribs.
Friday Peter & I got some more sheeting done on the top of the wing. The first piece was the curved middle piece sheeting the middle of the wing.
In order to do this we cut a piece of 3/32“, 4″x62”, to make W-SH-2 to go to curve out to between the middle of the ‘enclosing’ ribs. To determine the curve we tried different plastic curve templates Peter brought until we found one which provided a curve to our satisfaction. To aid in this we had marked where the curve should start and end to leave enough hang over for the bottom portion. I then traced it and cut it out with the utility knife.
Wednesday we started the process of sheeting the wing. Prior to actually sheeting we went over the whole wing doing some sanding, removing any excess glue gobs, rough edges, etc. making sure everything was finished as best we could. This is to make sure the sheeting sits down properly and eliminate as many covering issues/bumps as we can.
Once that was done we trial fitted how we wanted the first set of balsa sheets (W-SH-1, 3/32 “, 4″x62”) to fit. Based on the diagram (Wing Step 3) the butt joint isn’t in the center, so we used a full sheet for the first part and then will trim the excess (seen in the bottom & top images) from the second sheet.
Sunday we focused on getting the ailerons glued together. This aircraft has some very nice sized ailerons. 🙂
We needed to figure out how to determine the size of the 1/4” x 1/4” balsa stringers we’d need, and which piece to start with. Ended up temporarily putting in place the WT1 (1/8” Ply) wing end tip piece to measure the length from the trailing edge of the wing to the trailing end of WT1. This gave us the length of the outer edge balsa stringer of the aileron (smaller piece).