After we cut and tested all the parts several times without glue, it was time to start the A1-D construction. It is very important, with a structure like this, to get the best assembly order and stick to it. There are plenty of slots to align and some parts just cannot be put in place after some others.
This is why it took a while to proceed with the construction phase. Once I got a good plan, i glued the front fuselage together in one single process. Then I put it was on the assembly jig we constructed last year for the Juliet. For reference, I put a drawing printed from the 3D program on the bottom of the jig. This made very easy to align both the blocks and the single parts, while keeping everything straight.
After the front part cured, I started to close the tail. Here there are another two quite big pieces of carbon-balsa sandwich. These form a very strong structure which shares both the loads of the big rudder, and of the tailwheel. Additionally, they incorporate the slots to put the servos of rudder and elevator in the tail for balancing purposes.
The top of the fuselage is made of two parts. One is part of the structure and goes from mid-lenght to the end, and the other one is a detachable canopy. The canopy is quite big. I made the woodden part completely out of balsa and on top of it theres a transparent plastic “bubble” which I thermoformed on a plug just as the one in A1-C. I then kept it in place with a slot in the front and a metal, spring loaded latch in the back.
For the motor cowling I tried something new. After making a plug with the same technique used on the first Juliet. First I made the shape using foam blocks that I glued together. Second, I covered the foam with fiberglass to make a rigid base. Finally, I used epoxy and microbaloons on top of the cured fiberglass to have a easier to sand surface. Once the part was ready, I made a mold of it and produced a lighter one using only fiberglass. I will explain the whole process in a separate post.
As opposed to the commercial A1-C Carbon-Kevlar one, I scratch-built the landing gear of A1-D. To make it stiffer and avoid propeller contact with the ground during landings, I decided to make it out of carbon fiber and fiberglass. I laminated several layers including unidirectional CF and fiberglass, with the classic ninety degrees carbon fabric on the outside for a nicer look. i then put the wet layup over the pre-made shape and pressed it until cured. At the end, to save weight, I bought some 70mm lightweight foam wheels from Hobbyking.
Like for the engine cowling, i will go more in detail about this process in a separate article.
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