Wednesday, June 22, 2016

Twin Prop Airplane

I have always been a little bit apprehensive about making planes.  There are two main reasons for this.  The first stems from the first plane that I made.  It was delicate and I was never sure how to make it stronger.  I repaired it several times until the damage was too extensive and was thrown out.  The second is the whole shaping the part until it looks good.  I like straight lines.  I am not the shaping type of wood worker.  However I had a friend ask me to make a plane for her grandson and I am not one to shy away from a design challenge.  The first ting I did was look at pictures and found a twin prop that I liked.  There was some big unknowns with this project and a lot of them worked out easier than expected but not easily explained.  First is that I wanted angled wings.  Was not sure how to do this until I realized I could taper the bottom of the plane and the groove would follow the angle on the table saw.
Then I wanted a clean joint on the bottom of the plane where the wings came together.  When setting up the order of cuts, if I cut all the angles at the same time they would all match.  Since I wanted the plane to last, I wanted thicker wings than the 1/4" material that was on the last airplane I made, so I made them 1/2" thick.  That looked really weird so the wings had to also be tapered like a real plane.  That taper was not fun.  I cut the stop cut on the bandsaw, scored the waste piece and broke it off.  Then there was a lot of sanding.  After a lot of work and thought, the tapered wing looked good.
The landing gear was the part that always broke on the first plane, so I took the easy solution and took it off.  The tail section was the last challenge.  I wanted sturdy and doweled.  So I grooved the horizontal piece to accept the vertical piece.  Before I glued the vertical piece in, I drilled holes in the groove through the fuselage.  Then installed the vertical tail, drilled into the tail and installed dowels.
The propellers and engines were more of a challenge to cut than to design them.  I will be reinforcing them with pin nails just to be sure they will not fall off.  Glue usually holds very well but not during crash landings.
There are a couple of features of this design that I am proud of.  The first is that it is a solid design.  I want to see how my kids handle it.  I am pretty sure they will do their worst.  Besides the tapered wings the other design element that I though was clever was the thickness of the fuselage.  It is 1 7/8" thick. This is two pieces of standard 3/4" material and a piece of 3/8" thick material.  The tail pieces are 3/8" thick.  The stripe that runs through the plane was planned and designed in.
This is one of the projects were I enjoyed the design process more than the build.  This just was fun to figure out the problems.  I really didn't know if it was all going to come together the way I had planned in my head.  I am not sure if these plans will go up for sale.  They need a lot of refinement and I will need to add images to the directions.  It is too hard to explain the procedure.

 This plane is made out of maple and walnut.  I still do not like the shape until it looks good but a plane with sharp angles looks even worse.  I will have to say that planes are a little less scary to design now.

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