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Fleet Biplane by CDW - FINISHED - Concept Models - 1:4 - Wood Construction


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This 1:4 scale Concept Models Fleet Biplane is going to be built to fly RC using a Saito 1.8 cubic inch 4-stroke engine for power. The engine will be converted from glow fuel to ignition/gas or possibly methanol fuel with no nitro additives. Have not fully decided yet.

When I am not ship modeling, I do a lot of scale model aircraft modeling as well. I prefer large models such as this 1:4 scale model, with a wing span of 7 feet.

I bought the model and the engine from private sellers on the classified section of a popular R-C aircraft forum.

 

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That's a lot of wood in that box. About 20 pounds worth. Finished model will weigh approximately 20-25 pounds ready to fly.

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The wings are generally the first thing I'll build when doing an airplane model.

These wings feature a built up main spar consisting of two spruce spars and plywood sheet on each side of the spars making a hollow spar. The pictures show fairly well how the spar is built. Makes for an extremely strong but light weight wing structure. Both the top and bottom wings on this model are equal lengths. 

Except for areas where required, this model will be almost entirely built using Tite Bond as the adhesive. Where higher strength is needed, epoxy and fiberglass cloth. Certain areas of the main spars receive epoxy and fiberglass due to the fact the wings disassemble with a connecting plywood spar that slides inside the main spars. 

A model this size demands that it come apart for transport, then assembled at the flying field for flight. With a biplane such as this, it will employ functional flying wires and turnbuckles to hold it all together. Some thought is required to make it all easy to assemble at the flying field, yet strong enough to withstand the stresses of flight and maybe a hard landing here or there.

 

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I lay ceiling tiles on my building tables to allow for pinning down the wood structures when I am building them on top of the plans.

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Once the fuselage gets framed up, the cabane wires and landing gear wires must be bent and built. Steel wire binds the joints then silver solder seals the deal. Both the cabane wires and landing gear are removeable.

This thing is starting to become rather large for my modest building room/area. I could move out to my 3-car garage, but it is not climate controlled and not very friendly to wooden models nor my body. The limits of my willingness to endure the drastic Florida heat and humidity will eventually force me to strongly consider insulating and air conditioning my garage.  ;)

 

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Now comes construction of the cowling. it's a rather humble beginning with some huge chunks of balsa, but gets more interesting as shaping and construction moves on. Remember and look the first pictures in this post. The real aircraft had a radial engine whose cylinders protrude outside of the cowl. Will need to find a way to fashion some dummy cylinders to make this have a scale look and appearance.

 

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To insure a proper fit, the cowl is test fitted to the fuselage along the way and shaped accordingly. Lots and lots of filing and sanding goes into this. 

 

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Here are a couple of pictures of the Saito 1.80 engine that will be used to power my model. Behind it in the background is a scale drawing of the actual radial engine cylinders in the 1:1 real aircraft. Remarkably, the Saito engine is very similar in size and profile to the real engine.

The Saito engine will fit where the cylinder faces down when mounted on the plane.

 

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Next, I have to find a way to recreate the radial engine cylinders that protrude outside of the cowling. I decided to use basswood to represent the cooling fins of the engine cylinders. So, I used my handy-dandy Olfa Cutter to cut a gazillion circles of various sizes for the cooling fins and spacers. A dowel fits through the center of the fins and holds it all together. Next, the various other pieces are carved from balsa blocks. Once I am satisfied with the first, prototype cylinder, I recess the cowl and fit the cylinder to it. 

Now, this same process must be repeated for the remaining cylinders.

 

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Once the model is framed up, then the (sometimes) tedious task of making certain the wings and stabilizers are all square is done. You must do some tweaks here and there to get everything lined up and the appropriate degree of incidence in the wings. With biplanes, this task is harder because there are two wings and it's just the nature of the cabane wires/struts that fasten the top wing to require adjustment to fit.

 

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Once everything fits and is square/aligned, then it's time to cover the framework.

Frames are prepared by sanding and applying a product called Balsarite. This product is brushed on over the entire framework and is a heat activated adhesive. This adhesive serves to hold the covering material in place and adhere it to the framework.

The covering material I used in this application is called Koverall, sold by Sig Models. Koverall is a lightweight polyester fabric identical to that used on full scale home made and other light aircraft. It is first cut to fit then ironed onto the framework. The heat of the iron serves to activate the adhesive previously applied to the framework and it shrinks the polyester fabric to a drum-tight condition.

 

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After all the framework is covered with polyester, it is then covered with multiple brushed on coats of Nitrate Dope. I purchase Nitrate Dope from Aircraft Spruce, a company that carries all sorts of home made/experimental/light aircraft products. It is the identical product used on full sized aircraft. It is highly volatile and gives off a lot of smelly fumes. Very much a product to only be used in very well ventilated areas or even outdoors if weather conditions permit. This clear dope also fills the weave in the fabric making it fuel proof and further serves to tighten the fabric.

When finished this way, the model becomes very strong indeed. 

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After the model was covered with dope and dry, I prepped the painted the entire model using sprayed on epoxy paint. The graphics were done free hand and do not represent any actual aircraft i am aware of. The 1:1 Fleet Biplanes were rather dull and bland in the way they were finished/painted. I wanted my model to stand out and be as easy to see while in the air as possible.

I put the finishing of the model on hold after my brother passed away last year. I am resolved to finishing and flying it this coming year. Not very much remaining to do at all. 

 

As you can see, it is rather large, taking up almost the entire width of a driveway.  :cheers:

 

It should fly nice and slow, and be very aerobatic.

 

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  • 2 weeks later...

 

a23dfXM.jpgI am in the process of rehabilitaing one of these. I have seen reports that the tail surfaces are not torsionally stable (elevators especially, I think). I add corner gussets. My cabanes appear to be glued in, but I may make another attempt to remove them after seeing you covering photos. Wish my building abilities were as good as yours! Denny

Edited by DennyG
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  • The title was changed to Fleet Biplane by CDW - FINISHED - Concept Models - 1:4 - Wood Construction

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