Electra-10 Airplane – Part 2


May 2012 – Amazing Wonders Aviation VBS Prop

The first piece of Insulfoam I cut out was the two tail fins. This taught me a lot about precision foam cutting techniques. I had to dial in the heat in the cutting blade so that it sliced but did not melt away a half inch gap. The difficulty was that the foam block was 4″ thick and while I traced the outline on one side I could not see if the edge of the knife was following the outline on the other side. I overcame this on my next cuts by having Ben hold the far edge with a pair of lock pliers to guide the cut along the outline. Ben has a great amount of experience in sanding and shaping foam. While his subjects are usually miniature houses and small scale, the same principles apply to large scale. By sanding down the rough block cut we achieved the smother beveled edge look we were going for. I have high hopes that once the foil and metal tape are applied the Insulfoam will look like a metal plane part.

  

Using an extra block of foam from my Easter Crosses project I made a mock up of the planes skin. I would use an incredibly long roll of 12″ foil, each sheet would be spaced an inch apart to allow contact between the metal plumbers tape, the foam, and the foil. This would bind it all together and by running the sheets in parallel with the structure of the plane it would create the illusion of metal skin.

As I approach the main build I decided to make a scale paper blueprint of the plane. This would allow me to place the integral superstructure inside the drawing and pull wing and tail measurements without converting for scale. I found some extra gray butcher paper in our children ministry closet and began to lay out the plane. First the main body, then each wing, and finally the tail and engines. The mega-blueprint folds up into a nice two foot square.

  
  
  

Superstructure
A lot of time and effort has gone into the design of the interior superstructure of the plane. Since this 12′ long vehicle will be hung at least 14 feet in the air inside our worship center, safety is paramount. The main cross beam will be 6′ piece of half box unistrut conduit. This gives the main body of the plane a 6′ width allowing it to fit through a standard door. The plane will be assembled in four large pieces.
  1. Main Body: A six foot wide section of wing containing both engines, this piece will span from the nose of the plane to the cross beam for the tail.
  2. Tail: The five foot wide tail section will bolt onto the main body.
  3. Left Wing: A four foot piece of unistrut will be embedded in the wing and have a 1′ overlap with the main body cross beam.
  4. Right Wing: A four foot piece of unistrut will be embedded in the wing and have a 1′ overlap with the main body cross beam.
As this diagram illustrates, the unistrut (orange) will be made in three pieces to allow the wings to be both removable for transportation yet securely fashioned to the main body at the anchor points.  Down the main body of the plane will run two corner metal flanges. One on the top, and one on the bottom. Each 10′ flange will be nailed into the front and rear foam pieces as well as the center wooden cage section. The center cage will connect the foam pieces to the metal unistrut and bear the weight of the plane onto the landing gear and the two main anchor points.
  
 The next step will be main assembly of the center body and the wings. This will be comprised out of cardboard spars constructed around the main unistrut beam. A paper skin will be stretched over the spars and eventually everything will be covered by foil and metal tape. The first priority is safety, the plane must hold together with enough rigidity and strength to support itself from the anchor points. Part 3 will have some great progress pictures of the engines and the plane fuselage.
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4 thoughts on “Electra-10 Airplane – Part 2”

  1. The Lockheed I am intenf=ding to build will span 155 inches, The drawings shown on previos page, at the begining oof you project, are the best ones I have seen. How could I get a copy of them?
    I will appreciate your assitance..

    Carlos

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