Though my plane according to the plans was complete, Monday I truly completed my aircraft!
Outside of the plans, based on club members experience, I added support wires to the tail. You can see them installed in the featured image above. The reason for this addition is that a known flaw in the design of the aircraft is the weakness of the fin. If you were just flying in circles and figure eights you would be just fine but as soon as you started performing loops and rolls you would have a problem.
That problem is that the forces applied to the fin during these maneuvers would cause the tail to twist making the aircraft unstable in the air. This instability, and perhaps damage, leads to a lack of control and I believe even the potential for the fin to break.
The wires were created by John based on the ones installed on his 4 Star 60. He sautered the ends to bolt to the surfaces onto the wire. The are adjustable for length as you want to make sure they are at about the middle of the top of the fin as well as the middle of the outer edge of the stabiliser into solid wood, but not to close to the edge to ensure a firm hold.
Doing one at a time you line it up and mark where the holes need to go into the stab and the fin. Adjustments needed to be made on the ends to ensure they sit flush with the surface of the aircraft. You then drill out the holes, ensuring you go through in a straight line as you don’t want to be at an angle. Next you put the screws through (screw it in once required) and then put a locking nut on the screw through the stab. Can leave the one through the fin for now.
On Saturday I got to work on my plane again and made some more progress on covering and installation of the fuel tank. One of the discussion Peter & I had in a previous session was what I’d like to do with the cockpit, use covering or paint it. I decided to go with painting it as I felt under the heat of summer with no airflow under the canopy that covering would wrinkle and be a waste, so Peter stained the cockpit green, seen at the top.
I continued where I left off last session by completing the covering of the fin in white. I was able to utilize the knowledge I learned from John in my last session about covering. I was impressed with the result. I didn’t quite get it right the first time so had to switch around the covering and start again (as the glue along the one edge was no longer good after pulling up the heated covering). Throughout the process I had to make some incisions at the top and bottom to allow the covering to come around properly, which includes removing excess when I could.
Tuesday was an excellent covering session and nice to get in back to back days working on my plane. Covering is definitely a time consuming task and the tail with all its intricacies took a lot of concentration and patience. Throughout the process I learned how to do things better, namely so that I do not get the wrinkles when rounding corners causing a jagged/rough looking edge with wrinkles in the fabric.
I started with covering the bottom of the stabilizer in orange and the top yellow to match the colour scheme of the wing (picture below and above, respectively). Measuring the surface at its widest point and longest point to cut a piece at those dimensions plus three inches to have play and room to grab. For each piece the process I went through was (see bottom of article for better approach):
Woodpecker the surface
Line the piece up at the fuselage
Tack it down starting at the centre and working my way out
Start up by the fuselage and apply heat from trailing edge to leading edge (width of iron)
Repeat moving down the stabilizer
Ensure all edges are fully ironed down
Cut excess from trailing edge and tip
Fold leading edge (as have excess) around the entire edge, pull tight & iron it down
This is where the wrinkles really come in!
Trim excess from trailing edge
Doesn’t necessarily look pretty as the wrinkles cause the blade to catch preventing a clean line and instead you get a jagged rough line
Last Tuesday I got to work on my plane again and been so busy since I’m only now getting around to blogging about it.
The first thing we did was install the wire for the tail wheel. This involved first bending the tip of the wire into a 90 degree angle and ‘sanding’ the wire to rough it up a bit which allows the glue to stick better to hold the wire into place. Then needed to drill a hole into the button of the rudder for where the end of the wire (the part bent up at an angle) will slide into. This provides a sturdier fit into the rudder, since this wire steers the tail through the wheel/rudder connection.
The remaining part of the wire that goes along the bottom of the rudder needs to be recessed into the rudder itself so that it is flush. In order to accomplish this I first lined up the wire and traced two guide lines along the bottom. Using the guide lines I drilled tiny wholes along its length to carve out a groove. I then alternated between using a drill bit to run along its length a tiny file to sand out the inside. I alternated and repeated until upon one of my checks the wire sat down into the rudder to my satisfaction. Note that we used the plans to figure out how far back the wire needed to go and also need to ensure that not to much sticks out at the leading edge that would interfere with rudder movement.
Once that was done and glued into place we then cut a piece out of a fiberglass sheet such that it would wrap around about 2 inches on each side. I then brushed glue over the fiber glass, ensuring to role any air pockets out of the fiberglass over the wire and down the sides. Once this was done it was left to dry.
The fiberglass provides additional support / reinforcement to the tail wheel assembly.
Next I went back to working on the wing and installed the invasion stripes on the bottom of each wing panel, seen in the feature picture at the top. Placing covering over top of covering can lead to an excessive amount of air bubbles forming as air gets trapped between the two layers. In order to help mitigate this issue I used the Top Flite Woodpecker Perforating Tool:
Had another great building session with Peter today. I started with covering the other wing tip in green, which again took a lot of time and due diligence! I was able to do this one by myself as I remembered what I learned from working with Peter & John while covering the other tip, bottom of this post.
Afterwords I glued the balsa tail fairing blocks into place. In order to do this I cut two 3″ lengths of 1/2″ balsa triangle stock to serve as tail fairing blocks. I then marked one for each side of the fin. Peter showed me on the first one how to angle the back so it tapers from front to back. You mark a line for the max you can go for your tapper as well as marking where F6 (Former) rounds against the block as you then sand to achieve the desired taper at the back and to get it to be ‘aerodynamic’ with F6, as you don’t want it to be squared up above creating unnecessary resistance. The reason for these two blocks is that in the design the fin is not sturdy enough without them and can cause the fin to flutter or break off during flight. These two fairing blocks provide additional support to the fin to help prevent side to side movement.
After that was completed we poured some glue into a small container and mixed in another compound with the glue in the original container. The compound makes the glue thicker, so you keep adding and stirring until you get the consistency you are looking for. We then went over the sheeting on the wing and found any little whole, indent, ding, ‘non-smooth surface’ we could find and filled it with the mixture. We then left it to dry. The beauty of this mixture is that it is easy to sand, so next time I’ll sand for a smooth finish.
Today I got over for another great building session with Peter. Peter kindly had the sheeting for the (tail) stabilizer of my plane glued together. We marked out one side of the sheeting tracing the framework with a pencil to know where the stabilizer framework had to go on the sheeting and then flipped over the framework. I placed glue along the entire surface that was coming in contact with the sheeting while Peter spread it. I then flipped over the framework, placed it on the sheeting, wiggled for good glue disbursement and then temporarily pinned in place while I glued the other side. I removed the pins and placed the other set of sheeting onto the tail. Peter then placed weights to hold everything snuggly together while it dries.
The next step was buidling the fin. Found it on the plans, pinned it in place followed by pinning wax paper over it. The next step was to find the pieces and line them up on the plans followed by gluing and pining. I then measured, cut, and sanded the rectangular ‘centre pieces’, need to remeber what their called and will update, until they fit snuggly but not to tight such that they are pushing out / warping the pieces already glued and pinned.
After completing this phase I had what’s below. The long piece, trailing edge, is not attached yet however the bottom part has been sanded to give the desired angle and will be cut at the top when the time comes.
The last part for the day was to prep the sheeting for the fin. You always want to go oversized to ensure you cover everything and then can (what I imagine and will learn how) cut it down to size. This time Peter and I did it together. Peter tapped the back side using special tape (leaves no residue) and then folded the pieces back so I could run glue down between, top to bottom. Then we layed them down flat, on glass, and wrighted them down while the pieces dry together.
That wrapped up another fun building session! I’m definitely learning little by little.
Update 10/22/2016: I couldn’t remember the name for the ‘centre pieces’, it’s ribs
Yesterday I bought a Sig 4 Star 60 kit off John from our club. I’ve been so excited and nervous about building I wanted to get a start on it ASAP so I called up Peter today, as he’s teaching me, and got over to his place after supper.
We opened the box, seen in the image, and went through everything. Noticed that for the plans we had two 2 of 2 pages and we were missing page 1 of 2 of the plans! Thankfully a quick trip to Johns and he was able to provide us with the missing plan.
I got a start on the tail this evening after an intro into learning how to read the plans which includes how to tell the different tyes of woods and the way the grains are going. The grain direction is important as it provides strength.
They do recommendtwo copies of the plan as then you have one you keep in good condition and another you place on the table for working on. We cover it with wax paper to keep the glue off but still poking pin wholes through it.
I punched out the required pieces and then sanded any edge that will be glued to remove the ‘burn’ marks from the laser cutting and the rough parts from where a piece is punched out.
Once that’s done made sure everything was lining up properly and glued the framework together and pinned to make sure it’s held tight. This didn’t include the 6 pieces for support.
The 6 pieces were done from biggest to smallest (this allows for if you cut to small you can use it for a smaller one). Theirs one piece of wood that’s the appropriate width and then I measured and cut (using a bandsaw) each piece. Before cutting the next I’d sand the end down until their was a snug fit. Don’t want it to big or else it’ll push out the frame and cause warping/twisting of the frame.
Once I got them all fitting together properly going by Peters markings as to where the overlay stopped I placed glue on the surfaces that would be contacting the ‘main’ (top and bottom) pieces.
Throughout this process we’d pin the wood down to the table to ensure everything was snug and flat.
That sums up today’s building process as left the glue to dry. I was uncertain how I’d like building but if today was any indication I’m going to love it as I really enjoyed this build session. I know I just started, so will have to see how good my patience and ability to learn construction skills really are!