35% Extra 330S

Construction (Page 4)


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Other then some final assembly processes, like radio, switches, batteries, tank, etc. The Extra is now to the point of being prepped for paint and covering. Although I have a general idea of where and how all my internal components will fit, I usually leave those final installations steps for after painting. My reasoning is that this way I can see how the plane will balance, and come together, before my final placement of all the major internal components.
      Here are a few pictures of the completed plane, before I strip it down and prepare it for sanding and filling.

The first step in preparing the plane for painting, is sanding and filling in any defects that you may come across. But before I do that, I want to make sure that there is a good fit between the wings and the fuse. No matter how hard you try, there is always going to be a bit of gap between the fuse and the wings/stabs at the root. Sanding the root of the wings/stabs will get you close, but to get a perfect fit, you will need a little filler.
What I usually do is place a piece of wax paper on the fuse where the wings/stabs mate. A little spray glue on the wax paper will keep the wax paper nice and tight to the fuse. Once that is done, I then mix up a little filler with West System Epoxy, and West System 404 fairing filler. The combination turns the epoxy into a putty type filler that is very easy to sand. I then place the putty around the root of the wing/stabs. Generally a 1/4" thin bead around the circumference of the root is plenty. Once that is done, I then mate the wing/stab to the fuse. The filler will ooze out, filling any gaps.
        Here you can see some pics of it being set up. I do one side, let it dry, then flip it over and do the other side.
  Once the epoxy has dried, the final step is to remove the wings/stabs, and sand the edges. As you can see in the picture you are left with a 1/4 inch ring around the edge of the root, that creates an almost seamless, seam.


The wings and stabs are now covered using Monokote. I'm not going to get too involved in how I cover, because I don't do anything special, other then cover how Monokote is designed to work. I'm just showing some completed pictures of the colour scheme I'm doing.

Now that all the fillets are complete, the plane is ready for the painting process. But before I get into the painting and prepping, I just wanted to mention for clarity, and for whomever may be interested in painting. The paints, primers, fillers etc, are all Standox products. Standox products are all very high quality automotive paints, that are typically found on more expensive automobiles.
The first step in prepping for paint, is to fill and sand down any defects that you may find in the glass work. Cracks, large pin holes, the seam, and any other unwanted variances you may come across. As I come across the defects, I use Standox body filler to fill in, or patch these spots.
   Here are a few pictures of the filling process. You can see the seams have been sanded down, and filled with the body filler. Once the seams are filled, I then give everything a good sanding with 100 grit sandpaper. Making sure that all the sheen is taken off the gel coat, and that everything is smooth. Any professional painter will tell you that the finish is only as good as the preparation, so take some time to prepare things.
Once you are satisfied, and feel that you have filled all defects, the next step is to paint on the first primer. But before you can paint, you need to mask off parts that you don't want painted, and you also have to figure out ways in order to hold your parts.
Here you can see a picture of all the parts that are going to be painted. In order to be able to hold the fuse for painting, I had to make a handle of some sort. So I installed a temporary tube through the fuse, then fastened the tube to the firewall and to formers inside the fuse. I will then use a workmate to clamp the handle for the fuse, thus allowing it to be spun while painting.  For the Wheel pants, Spinner, and gear, I used some scrap lumber and made some handle, fastened with screws. The canopy just needed some masking, and the cowl can just be placed over a can or something, that will support it while you paint.

Now that all the parts have been filled, prepped and sanded, the next step is to prime everything. Peter Woo, who has been a modeler for years, and use to own a hobby shop has helped me with the actual spraying. He now owns an automotive body shop, so he has allowed me to use his spray booth. The name of the primer used is Standox HS primer, which is basically a chalky filler primer, used to fill in the deep scratches and imperfections that are left from the filling process.  This particular type of primer has very chalky like characteristics, with a tan like colour, which make it perfect for this sort of application. Unfortunately, I forgot to bring my camera to Peter's shop to take some pictures of this process, but I'm sure you get the idea. Once the primer was sprayed, the next step was to sand it all down. Again I did all of the sanding at Peter's shop, for it is a dusty process to say the least. Initially I used 220 grit sandpaper and a block to sand down the primer. You want to sand it down to the point where the primer begins to have a translucent appearance or you begin to just barely see the original finish come through. Once I was satisfied with that, I then water sanded the hole airplane with 800 grit sand paper. This got rid of any fine lines that were left from the 220 grit sand paper and left the airplane with an ultra smooth finish.

Now that the airplane is primed and sanded, the next step is to apply the white basecoat. The colour scheme I chose is predominantly white, so it only made sense to spray the entire airplane with Standox basecoat white first, then apply masking for the eventual colours. The white was sprayed at Peter's shop. I then took home all the parts that needed masking where I could be in the confines of my home and take the time to mask off the lines properly.
As many of you know, an airplane has many curves and contours. So placing masking tape on a fuse and expecting to have straight lines is not an easy thing to accomplish. Especially when you try to place the masking tape on free hand and by eye.  In order to achieve relatively straight lines, I had to make a jig to mark pencil lines as a guide for the tape. What I did was to make a small base out of some ply wood, drill a hole, glue in a piece of dowel (in my case I had some left over aero shaft) then tape a pencil to it. I then leveled the fuse, and went across the fuse, and every 5-10" drew a faint pencil line. Because the pencil is at a fixed height, and the table is straight, my line is at the same point all the way around the fuse. This in turn gives you a proper line to follow and is especially helpful when going around curves like the front of a cowl as you can see in the picture.
   The tape used to mask the edge of the lines is called 3M fine line tape (the blue one) It comes in various thicknesses, from 1/16" to 3/8", depending on your application. I used 1/8" because it is the amount of seperation I want between colours. This is designed for the actually edge of where you will paint, and once you define your lines, you need to mask the rest off in a conventional way, a la masking tape, paper, etc. (see photos)
      Now that all the hard stuff is done, the final step is to actually start painting. Here you can see some pictures of the parts being painted in the spray booth.
     After the white was sprayed the next colour sprayed was red. Once the red was sprayed, the fuse was flipped upside down,  and masked off for the black and silver stripes.
   Finally and now that all the colours have been applied, the last step is to spray the clear coat, and leave to dry.

Final Assembly:
 The final assembly was pretty straight forward. All the internal electronics and tank locations were pretty well set and just reinstalled after the paint was dry. As far as decals and art work are concerned, I made my own using a bubble jet printer and some clear adhesive paper available at any local stationary store. Here are a few pics of the final installation:


Here is some pics of the Extra at the field ready to fly:


Click here for flight tests and specifications

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Extra parts list






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Last Updated 05/03/2007