Ray's Home Page 2

Airplane Modeling
From Rubber Band Power to Radio Control Gas

      (Long, read only if you have the time or the interest in this hobby)

This is a work in process
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My second plane was an Ace "Bingo", a low wing, six foot span plane that I liked the looks of the first time I laid my eyes on it. Of course I couldn't just build it as it came out of the box. Since I had a 6 channel radio system I wanted to use all 6 of them. I built in flaps (on 3 position channel 6) and designed and built in a retractable landing gear into the wing (on channel 5). The plane final weight is 6.5 pounds. I went through 3 mechanical landing gear kits before I finally installed one that was strong enough to support the plane on take-off and landing. I can still picture the plane landing a number of times and the landing gear collapsing, allowing the plane to belly-womp into the gravel. I did have the foresight to cover the plane with cloth covering even thought it did add some weight.
 

Head On

Three Quarter

Gear and flaps DOWN

Gear and flaps UP
                 One Quarter View
            Rear Quarter View
The engine is a K&B "65 Sportster", and I've never been sorry that I bought it. It also starts very easily and runs beautifully. Most of the members at the club have more powerful engines and seem to have more problems than I ever did. Maybe it's because I break in my engines like I used to in my free-flight days and don't abuse them by trying to get every ounce of power out of the engines by running higher than necessary nitro fuel and running their engines too lean.
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Four Ft.Speedster showing Add-Ons

6 Ft Assembled

6 Ft. Read to Go

Another View
What you see here is an attempt to make a perfectly symmetrical plane that would have a thick airfoil for keeping the speed down while being able to perform all of the pattern maneuvers that are possible. This plane had the K&B Torpedo Greenhead  installed, and the engine performed very well for as many years as it laid around not being used. Unfortunately, I didn't cycle my batteries often enough to detect a bad receiver battery and control was lost during one of the maneuvers, resulting in a crash that provided a lot of insight into component design. I called it the Yellow Streak. Another lesson that I learned, don't use white or any light covering on the underside of the wing as it is almost impossible to see when the sky is overcast. It's OK when the sky is nice and blue, but who can predict the weather.
 

The main development in this design is the use of tubular spars and tubular leading edges. The tubes are made up of 2" gummed paper tape (the kind that was used to tape packages for shipping that you had to wet with water) (getting rather hard to find) wrapped on a bias over plastic vinyl water pipe with the gummed side up and then wrapped again on the opposite bias with the gummed side down. The wrap is then soaked till the water wets the glue between the paper and then allowed to dry. Two more bias layers are applied with the glue down on each wrap, and soaked and dried. After the tube is completely dry it is removed from the pipe and a solution of epoxy diluted 1/4 with denatured alcohol is applied to the inside of the tube and allowed to cure. (I found that I could speed up the process of curing and at the same time impregnate the paper tube better if I heated it with the heat gun). After the inside has cured, a solution of the same kind is applied to the outside of the tube and cured. This made for a very strong and lightweight spar and would be good anytime a long, strong, light member was needed. This was a long and tedious process but I figured that if it was viable the tubes could be purchased from the paper mills that make the tubes for christmas wrap. Their tubing seems to be about the strongest and thinnest that I could find. The tubes would then only need to be impregnated with epoxy.

The wing was designed as a one piece 4 ft. center section with a 1 ft. wing tip on each end. They were attached using pieces of the pipe that they were made on, to be inserted into the matching tube in the main center section and pinned in place. This would allow transporting the plane to the flying field with all of the radio connections in place, since everything was contained in the center section including the ailerons. At the field the wing tips would be installed if a 6 ft plane was desired, or the plane could also be flown as a 4 ft. hot-dog.

The stabilizer was also perfectly symmetrical and built with the same kind of tubing (although smaller diameter) (I used a bow hunters arrow shaft) as the wing and was mounted on twin booms, which were attached to the spar. A mistake that I made was to use 3" x 1/4" balsa for the booms. They proved to be weak and unstable on the first flight and the booms broke on the first landing. Two revisions had to be made. One was to install 1/2" x 1/4" strips along the center line of the boom and the other was to attach 1/2" x 1/4" strips across the booms and anchored at the center. These changes were sufficient to continue testing the concept until the battery problem resulted in the pictures that are above. The picture looks much worse than the original crash site because I cut the covering to remove the landing gear and all of the radio gear. The worst damage was to the broken booms, and the spar broke next to the fuselage. Someday, I will replace the booms with light ply and repair the spar and it will fly again.

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I had always wondered if one of those all foam gliders could be made into a RC plane. I bought one ($5.00) at WalMart and assembled it, but with fiberglass tape along the top and bottom length of the wing to keep the flexing down. I bought a Cox .049 Dragonfly  and mounted it to a piece of light ply and installed it on the squared off nose of the glider. The fin and stabilizer needed to be enlarged so I just did it by adding a rudder and an elevator to the original parts. Cutouts for the receiver and servos were made into the fuselage at the approximate locations (I taped them to the fuse with masking tape for judging the CG). Push rods of 1/8" dowel were installed with 1/32" wire ends. The Cox .049 Dragonfly was run until I could start it with the starter spring on the first try. The hardest thing in getting it to start was getting the proper prime. It doesn't have a venturi or exhaust port like most model engines and needs a drop of fuel in the exhaust slot.
 
 


Note the Enlarged Fin

Cutouts in Fuse were from Servos

The first flight was a long glide with the engine screaming, but it was all down hill and when left or right control was given the nose dropped even more. Way too heavy! It didn't need more power, just a lot less weight. The engine control and elevator servos were removed The engine would be run wide open. The elevator was linked to the rudder. When the rudder was deflected to the right or left, up elevator was applied. This solved the weight and control problems but the flights were more like my first rudder only RC flying. It works but I'm not enthused enough to pursue it any more.

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I was so impressed with the tubular spar that I decided to design and build an even more diverse model. Firstly, since the usual real reason for having a fuselage is to contain the radio gear, batteries, actuators and fuel tank, and attach the tail feathers, I decided on a profile model with as much as possible stuffed into the wing as it was in the Yellow Streak. This design is only similar to the Yellow Streak in that I used a tubular spar in the wing. The rest of the design is completely foreign to model building as I know it.

The profile is made out of a sheet of rigid foam, such as is used to make letter or object profiles for decorations. I bought mine at a hobby shop. It came in a sheet 1 ft. x 2 ft. x 1/2" thick. Using 3M Super 77 spray adhesive, I laminated 1/16" balsa to each side of two of the sheets. I then cut out the fuse profile and the stabilizer. The fin is part of the fuse profile. These were then edged with 1/16 thick balsa strips using Elmers Carpenter Glue. I also inserted a piece of 1" x 2"x 1/2" thick balsa into the area where the landing gear was to be attached.

The wing is made up of the tubular spars, and all of ribs are cut from the same 1/2" rigid foam but are not laminated. They are slid on the tubes, located, and bonded with E C G. Leading and trailing edge are 1/2" x 1/4" balsa on edge and laying down. Not knowing how the rigid foam would react to the plastic covering material, I edged the top and bottom of each rib with Scotch tape. This resulted in a smother finished surface on the wing. I also made sure that I didn't use a light colored film on the bottom of the wing. The plane is hard to follow when it is 2 or 3 oops high and especially when the sky is overcast.

This is the plane and it has the  K&B Torpedo Greenhead installed in it with a Tatone muffler and a Vecco carburetor with a Bramco venturi bar and a throttle arm for RC.
 
 

Foam Profile model

In the above picture the rigid foam is shown in its applications, in the sandwich form and as a wing rib. The airfoil shaped, laminated rib is actually the cut-out from the fuselage for insertion of the wing.

These are actual parts of the various epoxied tubes that were used to build the experimental models. The biased wraps are visible on the outside of the tube.Color is cured epoxy.

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Here are some of the ancient RC components that I found in the K&B box that was in a drawer in my bench. Across the top--the K&B box--a Mighty Midget box--two crystals in their original plastic cases and five loose crystals [(I don't know where the extra crystal comes in since they were always paired up (transmitter and receiver)]. Middle row--a Mighty Midget motor--a peanut tube used in the receiver--a slide switch--a bulb and coil that was slipped over the transmitter antenna for checking transmitter output,mighty crude but it worked. Bottom row--K&B Allen Fury Red Head Engine with a Vecco carburator--Two original Spark Plugs (not glow)--clamp on exhaust adapter for flying with RC.

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Some of my other distractions are, working with oils to create conceptual visions.
This is really a work in progress


SWAMP

4 SEASONS

Last updated: 07-12-01

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