Foam Plate Cloud Tramp

introducing the FOAM PLATE CLOUD TRAMP

Responding to a discussion about airplanes made from foam plates and a proposed Foam Plate Airplane Contest, I started working on a foam plate airplane based on Cloud Tramp proportions. I’ve wanted to build a foam CT anyway.
I can get a 2″ x 5″ rectangle out of the 5 1/2″ flat center of a 9″ foam plate. (Later I found 9″ plates with a 6″ flat center and built a slightly larger Foam Plate Cloud Tramp. Now I hear there are 10″ plates which might make bigger planes.) Normally the CT has straight dihedral, but this makes for a somewhat complicated wing saddle join at the center and two 5″ panels make only a 10″ wing. (Actually an 11″ span CT wing would have a narrower chord and could go farther across the plate so it could be a full 11″ span, half size. It could be done. I may do it.) I wanted to keep it simple enough to post on EndlessLift where novices might be able to copy it. I decided to go with a 2″ chord and three panels, 15″ span, flat. A 2″ chord would be 2/3 normal, which would scale to 14 2/3″ span, close enough to the 15″ of three panels. (Actually, the rounded tips would allow slightly more than 5″ tip panels, but then that would indicate slightly more than 2″ chord, which would reduce the center span slightly, on and on, I decided to keep it simple.) The center panel goes straight across a simple rib attachment to the stick, no complicated double beveling required. The tip panels would be angled up to produce a polyhedral (trihedral) wing. Wing panels are crease cambered at 10, 20, 30, 40, 50 and 60% chord. It is possible to heat-form sheet foam into a smooth airfoil, but I want to stay away from heat and ovens for what might become a classroom or scout troop activity. A standard commercial 6″ prop assembly is a little larger than the 5 1/3″ diameter of a 2/3 size, but a little extra prop diameter is OK. This puts the prop shaft under the stick, so the wing goes on top. The downthrust built into the prop assembly dictates a corresponding taper under the back end of stick for the tailplane, to keep it aligned with the thrustline. The wing ends up flat on the stick, no incidence necessary. The downthrust of the prop shaft combined with the elevated zero lift line of the airfoil produces enough incidence to provide lift. Stick length is 12″. I used 1/8″ x 1/4″, with a 1/8″ square bit to fill the prop hanger. The 10″ tailplane scales down to 6 2/3″ which won’t fit inside the 5  1/2″ flat center area of the plate, but the round tips allow a slightly shortened 5 1/2″ span. (Later I will show how to make a full span tailplane in two parts.) I considered increasing the chord to compensate, but didn’t. Fin and tailplane fit on one plate, so total required is four foam plates. Wheels would scale to 0.83″ diameter, so I used 3/4″ P-P plastic wheels. About a 10″ length of 0.025″ steel wire makes adequate struts and axles for the landing gear.
With the design specified, I gathered the necessary materials and went to work. Worked all night, finished just at daylight, had an 11″ loop of 3/32″ rubber strip handy, left over from an AMA Cub class, positioned wing to balance at 40% chord, took it out onto the driveway and put in 150 turns. It went up steeply and slowly about roof height, circling left about 15′ diameter. Put in a tad of right rudder. Took it out in the street, put in 200 turns, similar, but straightened out at the top and went across the street, over the car and into tall grass. Took it down to the intersection for more room, 250 turns, similar, but straightened, then turned right, came down in a tree. It was within reach, so I was able to get it down. Took it over to the small local park, similar flights from center of lawn, at 500 turns it drifted south along the trees. Moved to the north side of the field and this time with 700 turns it drifted north into a tree, had to go home and get the 30′ pole to get it down. I wanted to open the left circle and maybe make it go right-right. It has a right rudder tab. It seemed that the dihedral was not enough. Scale would have been 2″. I aimed for 1  1/2″, but it came out at 1  1/4″. I made a second wing, raised the tips a bit more while sanding the dihedral bevel to get 2″, still got only 1  1/2″. I think the sandpaper is compressing the foam and not taking it off. Went over to the bigger park a little farther away, put in 900 turns. Why, oh why, did I do that? It climbed steeply to the left, straightened out and flew straight out of the corner of the field, still climbing steeply, out of sight against the overcast sky. Lost from sight at about 37 seconds, still climbing. I walked all over the neighborhood looking. It is amazing how many small bits of white you can find around a neighborhood. Did not find it. Stayed up all night again making another, this time I cut the dihedral gores with a knife and only finished the faces with sandpaper. A quick test in front of the house shows very similar flight. Had to catch up on sleep and it was already too windy to fly and foggy when I finished. The 3/32″ rubber is way more than it needs. I am flying on a little more than 50% of maximum turns for this motor. It might go on 1/16″, or something in between. First one weighed 8.5 grams, second weighed 8.8 grams, motor weighs 1.4 grams. 27.85 square inches of wing area. The foam is about 0.056″ thick. Later I got it flying with a bit of right rudder and right thrust. Right thrust results from twisting the prop holder to the right. The flight pattern was consistently to the right, going up and coming down, so it stayed in the park. Here is a short test flight with 900 turns in the motor.

Here are pictures of #1 with the first wing, to show you what it looks like.
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On the table.
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In the sky.
Oh, the joy of free flight! Circling high over the field.

Building a Foam Plate Cloud Tramp

This is a long tutorial. Being long makes it look complicated. It is not. It looks complicated because I have broken the building sequence down into the smallest simple steps. Each step is simple. There are many steps, but each of them is easy. Once you have gathered all the tools and materials together on your work table, it may take you an hour and a half to two hours to complete the construction. Be patient, take your time, do each simple step and at the end you will have a great flying airplane.

Note – these directions are for foam plates with 5  1/2″ of flat surface in the center. Later I found plates with 6″ of flat surface. This tutorial was written for and uses photos of the build from 5  1/2″ disks of foam. The exact same steps are involved in building one from a 6″ disk, with the dimensions changed accordingly. The numbers to use with a 6″ disk will be given in [square brackets] where necessary. Some of the dimensions don’t need to change, like the wire landing gear struts.  At the end of this article I will also show you how to make a tailplane that is correctly proportioned in size from two pieces.

Print the plan

We start by acquiring a plan of the Cloud Tramp from any of several sources. The plan is half size, with outlines of the wing, fin and tailplane tips in full size. Volare sells Cloud Tramp kits in the USA and Flitehook sells them in Great Britain. The easiest way to get a plan in the size we need is online at Mike Parker,  Outerzone, or The Plan Page. These print out on letter paper. Print one out and measure the wing chord. For this project, we want a wing chord of 2″ [2  9/32″]. If it is not 2″ [2  9/32″], adjust your printer settings accordingly. I printed four copies so I could test the fit of parts on a foam plate, but you will need only one for making your patterns.
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We will use one plate for the fin and tailplane, three others for the three wing panels. We will be using cardboard patterns to mark and cut out parts. These are made from thin cardboard such as the boxes cereal, cookies or crackers  come in.

Make cardboard patterns

In thinking forward to the steps in the construction process, I decided to cut out three 2″ x 5″ rectangular wing panels, mark the edges for creases, crease them, bevel the joining edges, glue them together and then cut the tip curves last. This would ease the crease forming and alignment of straight edges during beveling and assembly. So the first pattern will be a simple 2″ x 5″ [2  9/32″ x 5  9/16″] rectangle.
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 Draw a line a bit more than 5″ [5  9/16″] long on a bit of pattern cardboard.
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 Mark a starting point on the line.
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Mark another point on the line 5″ [5  9/16″] away from the first.
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Draw perpendiculars to the line from both points.
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Mark 2″ [2  9/32″] out from the baseline on each of the perpendiculars to indicate the other 5″ [5  9/16″] edge of the rectangle.
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Draw a line through these two points to complete the rectangle. Draw a centerline 2 1/2″ [2  25/32″] from each end. Cut out the rectangular pattern.
Punch holes through the centerline about 3/32″ from each end to mark the centerline on the foam. With the steel straightedge and razor blade, cut around the perimeter of this rectangle to make the 2″ x 5″ [2  9/32″ x 5  9/16″] pattern for the foam wing panels.
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Mark along one of the 2″ [2  9/32″] edges every 0.2″ [7/32″] up to 1.2″ [21/32″]. These marks will locate the positions of the crease lines at the edge.

We need another 2″ x 5″ [2  9/32″ x 5  9/16″] panel for the curved gores at the ends of the wing panels where they join together. Mark out another 2″ x 5″ [2  9/32″ x 5  9/16″] pattern as before.
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On this one, mark 23/32″ (0.72″) [28/32″] from one of the 5″ [5  9/16″] edges on one of the 2″ [2  9/32″] edges. That 5″ [5  9/16″] edge will be the leading edge of the wing.
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At this marked point, mark 1/32″ [*] in from the 2″ [2  9/32″] edge. This point is the high point of the gore curve. This curve will be cut out of the end to allow the two cambered wing panels to be set at the correct angle to each other.
*[The exact number for the intended dihedral is 0.025758″, about 3/128″. 1/32″ = 0.03125″ will work fine for the 6″plate plane. This is a rough cut. We will let the sandpaper make up the 0.005″ difference. Considering that the width of a pencil line is about 0.01″, this is “close enough”.]
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Now draw the curve through the three points. This curve must meet four conditions.
1. It must pass through the trailing edge point.
2. It must pass through the leading edge point.
3. It must pass through the high point.
4. The tangent to the curve at the high point must be parallel with the base chord line. Drawing a line through the high point parallel with the baseline will help you judge this tangency.
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Now cut through the cardboard along this arc. Use your curve to guide the knife along the arc. The knife contacts the curve lightly. Do no try to cut through in one sweep. Make several light cuts. Keep the blade tangent to the curve. You will need to move the curve a couple times to match all parts of the arc. Finish by cutting out the remaining three sides of the rectangle. Mark an arrow along the curve pointing to the leading edge.
We will need a pattern to make the fin and tailplane. It turns out that the longest tailplane that will fit in the center of the plate is twice the length of the fin. The fin pattern can be traced for one half of the tailplane and flipped over to trace the other half. The same pattern can of course be used to make the fin, and also the two wingtips. So the one pattern can be used for all three.
At the end I will show you how to make a full span tailplane from two pieces.
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I taped the fin/tail/wingtip pattern to a piece of cardboard to keep it from moving around, then poked holes through the curve all around the edge, every 1/8″ or so, to poke holes into the cardboard underneath. I made sure to poke holes along the straight edge at the base a little in from the curved edges.
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This leaves a row of dots outlining the shape.
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Next I used a steel straightedge and a razor blade to cut through the two dots along the straight line at the base.
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I cut the pattern out about 1/8″ around the dots, then cut exactly along the curve formed by the row of dots.
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We will need a pattern for the balsa central wing rib. The paper rib pattern is cut out of the plan and taped to the cardboard. Holes are poked along the perimeter. Be sure to poke holes near the ends of the straight lower edge.
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Draw a line through those two dots.
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Mark a point on the line  1/2″ beyond the end of the arc.
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Draw a perpendicular to the line at the point.
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Do the same 1/2″ beyond the other end of the arc.
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Put a mark 3/4″ up on both of the perpendiculars.
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Cut along a line through those two marked points.
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Cut along both of the perpendiculars.
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 Tape the pattern to the work board to prevent it moving while being cut. Use your curve to guide the knife along the arc. The knife contacts the curve lightly. Do no try to cut through in one sweep. Make several light cuts. Keep the blade tangent to the curve. You will need to move the curve a couple times to match all parts of the arc.
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That completes the four patterns that we will need to make the parts of our airplane. Note the arrow on the gore pattern pointing to the leading edge. Note the crease marks along the 2″ [2  9/32″] edge of the 2″ x 5″ [2  9/32″ x 5  9/16″] wing panel pattern and the centerline. Also notice that I have marked out a rudder on the fin pattern. This was added after completion of the first plane. The layout dimensions will be given at the time I show the making of the fin. Go there now and mark it on your fin pattern.
Later I decided to add side plates to the rib to prevent the wing rocking on the stick. The side plate will be glued to the rib and the 1/16″ width of the hold down stick. It will extend down across the 1/4″ depth of the fuselage stick. It must be a long as the rib. We start by making a cardboard pattern.
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Select a scrap of cardboard large enough to contain the pattern. Make a straight cut along one edge.
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Put two pencil marks on this edge a distance apart equal to the wing chord, 2″ [2  9/32″].
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Draw a perpendicular to the straight edge at each of the two marks.
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Put a mark 5/16″ from the straight edge on each of the two perpendiculars.
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Draw a line between these last two marks.
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Align the rib pattern so it fits exactly between the perpendiculars and so the base aligns perfectly with the line.
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Tape the pattern to the cardboard.
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Use a pushpin to poke holes through the airfoil arc into the cardboard underneath. Make the holes close enough together to clearly define the curve.
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Remove the pattern from the cardboard.
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Cut through the cardboard along each of the perpendiculars.
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Rough cut about 1/8″ outside the airfoil arc.
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Cut precisely along the line of dots to finish the side plate template.

gather materials and tools

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The materials required to make this plane are:

Four 9″ foam plates from your local grocery store, or salvaged from a nearby picnic  😉 .

A 6″ Peck-Polymers propeller and bearing assembly. The hanger fits on a 1/8″ x 3/8″ stick.

A 10″ piece of 0.025″ steel wire for landing gear. Or a Peck-Polymers landing gear wire set will save you a lot of work.

Two 3/4″ Peck Polymers wheels.

A 3/4″ straight sewing pin for rear motor hook. Or a pack of Peck-Polymers motor hooks.

Four 3/16″ heavy dental elastics for wing hold downs.

A 1/8″ x 1/4″ x 12″ [1/8″ x 1/4″ x 13  5/8″] medium hard balsa stick for the fuselage.

A 1/16″ x 1/8″ x 3″ hard balsa stick for the wing hold down bar.

A 1/8″ x 1/4″ x 2+”  [1/8″ x 1/4″ x 2  9/32+”] medium soft balsa block for the central wing rib.

A 1/8″ x 1/8″ x 1/2″ balsa block for the nose block.

22″ of 3/32″ rubber strip for the elastic motor. You can get that from Peck-Polymers, too. This motor is good for test flights and small field flying. Longest flights will be made with a motor about twice the distance between the hooks. You will need to move the wing to properly balance with this heavier motor.

An O-ring for the motor. (Left out of this picture, see the next one.)

A tacky glue suitable for sticking foam together. Most glues for wood or plastic models contain solvents that will melt foam plastic. If you can smell solvent, don’t use it. Use a water based glue.

All of the balsa wood for my planes came out of my scrap box. You can find balsa wood at your local hobby, craft or art store. You can buy it online from Sig or Midwest.

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I store the materials and completed parts in a box to keep them from getting lost or broken.

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At the same time, I cleared all the boxes, books, bits and pieces off the back of my work table and arranged all the tools I will need for this plane across the back, in roughly the order, left to right, that I will need to use them. This eliminates the need to dig through my tool box every time I need a tool; I get everything out at one time.

Trace the foam parts

First we trace the patterns onto the flat areas of the foam plates.

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Hold the pattern firmly to the foam so it doesn’t slide around, and trace around it with a pen. Point the pen inward against the edge of the pattern. Trace three 2″ x 5″ [2  9/32″ x 5  9/16″] wing panels on three plates.

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On one of the wing plates, poke holes through the pattern near the ends of the centerline, to mark the centerline on the foam. This will be the center panel of the three part wing.

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Place the fin pattern along the edge of the flat area, right along the foot of the rising edge.

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Poke holes through at the corners of the rudder.

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Trace one half of the tailplane around the same pattern.

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Flip the pattern over, carefully align the pattern with the first half and trace the second half.

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That completes the tracing out of all the foam parts on four plates.

Cut out the foam parts

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Cut out around the three wing panels.

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Rough cut out the parts a little out from the edges.

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Cut the curved parts exactly along the edge with scissors.

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Use the steel straightedge to guide the blade while cutting the straight edges.

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Mark the crease points along the edges of the wing panels. Make sure they start at the same edge on both ends. They start at the leading edges, closest to the deepest part of the dihedral gores.

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Here are all the foam parts cut out and marked.

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Place the wing against a block of wood or sturdy ruler and line corresponding crease points with the edge.

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Press the overhanging panel down on the table top to form a crease along the line between the marks. Do this for all six corresponding pairs of marks on all three wing panels.

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Shape the airfoil to match the one on the plan.

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Lay out the three wing panels end to end with the center panel in the middle. We are going to cut the curved gores into the ends of the panels. Be careful to orient the wing panels and the pattern so their leading edges correspond; the creases start at the wing leading edge and the high point of the gore is toward the leading edge. There will be three wing panels, each different. The left panel will have the gore cut on its right edge, the center panel will have the gore cut on both edges and the right panel will have the gore cut on its left edge. Lay them out end to end and keep them in the same orientation as you work on them to keep track of which is which.

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Cut the wing gores off the four ends, as necessary.

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Place the wing on a 5″ length of Sig airfoil form with the leading edges together and one end sticking out a little beyond the end.

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Put the other end up on a 3/4″ thick block and lightly sand the bevel in the low end with a vertical sanding block. Sand away only enough to flatten the end surface and roughen it slightly for better glue adhesion.

There will be three wing panels, each different. The left panel will be sanded on its right edge, the center panel will be sanded on both edges and the right panel will be sanded on its left edge. Lay them out end to end and keep them in the same orientation as you work on them to keep track of which is which.

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You will know when this is done correctly when the wing panels are put together end to end with blocks under the tips and there are no gaps in the joints. They are now ready to glue together.

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But first let’s form the charming elliptical wingtips. Set the tip pattern on top of a tip panel with the tip opposite the end with the curved dihedral gore, the very tip aligned with the fourth mark back from the leading edge. Then cut around the curve with the knife.

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Turn the pattern over and trim the opposite wingtip.

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That completes all the foam parts.

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Sheathe the knife so you don’t accidentally cut yourself while looking for something else.

Assemble the wing

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Run a bead of glue along the inner edge of one of the tip panels.

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Rub the end against the corresponding edge of the center panel to spread glue uniformly on both edges.

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Align the leading and trailing edges with each other.

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Rotate the high points of the wing together while holding the leading and trailing edges together. Adjust so all the panels join smoothly. Hold until the glue sets. You can rest it on the leading edge to let the glue dry while doing something else, then come back and glue on the opposite wing tip.

Later I found that tape could help hold the wing joints together and in alignment as the glue dried. I started by putting tape on the under surface at the leading and trailing edges, pressed the wing panel edges together and put tape across the top of the wing at the high point.

Marking and Cutting the Rudder

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The rudder will be made by making two slits into the trailing edge of the fin and bending the resulting panel to the right along a hinge line. Line up the ruler along the trailing edge of the fin with the end at the base of the fin.

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Put a mark 5/16″ up from the base.

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Put another mark 1  5/16″ up from the base.

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Put a mark along the base 5/16″ in from the trailing edge.

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Draw a line up from that point, perpendicular to the base, between the two marks on the trailing edge. This is the rudder hinge line.

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Make a cut at the lower mark from the hinge line to the trailing edge, perpendicular to the hinge line.

Later I marked the lines out on the cardboard pattern and poked pin holes through the inner corners of the rudder. Then I could mark these points at the time of cutting out the fin by poking a pin through the holes in the pattern into the foam.

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Make a cut at the upper mark from the hinge line to the trailing edge, perpendicular to the hinge line.

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Put the fin on a block with the hinge line aligned with the edge and press the rudder down to bend it to the right.

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Adjust it so it is deflected about one thickness of the foam. We will adjust it later during flight testing.

making the fuselage

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Mark the center of the stick.

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Balance the stick at the marked point and notice which end goes down. Mark this end with a pencil. This heavy end will be put at the front.

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Put a mark 2″ [2  9/32″] from the back end of the stick on what will become the underside of the stick. This corresponds to the chord length of the tailplane. We will be cutting the bottom corner off the stick to form the tailplane taper.

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Put a mark 3/16″ up from the bottom edge of the stick at the tail end.

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Draw a line between these two points.

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Cut the excess wood away. (You can use a razor saw if you have one.) Be careful to not cut into the wood we want to keep. Cut a little outside the line. The excess will be sanded away to the final line.

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Put the stick on a block of wood to space it up from the table top, back it up with a stiff piece of wood and sand the taper to the line. Holding the squared sanding block snugly against the table assures that the sanded surface will be perpendicular to the sides of the stick.

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Apply glue to the top surface of the nose block.

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Glue the nose block to the front underside of the stick. Make sure it is flush with the sides and front end of the stick.

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The finished fuselage stick. Note that the nose block and the tailplane taper both go on the underside of the stick.

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Apply a thin layer of glue to the tailplane taper.

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Carefully center the tailplane on the stick and press it in place.

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Put it in an out of the way place and place a weight on the stick to hold it down until the glue dries.

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When the glue has dried on the tailplane, you may add the fin. Apply a generous bead of glue along the base of the fin.

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Place the fin on the stick, with the rudder to the back, and slide it around a bit to spread the glue. Hold it in place until the glue takes hold. You may want to block it in place while the glue dries. You can place a block on each side of the tailplane and a block on top of each of those, slid together to hold the fin in exact perpendicular alignment.

Adding the wing rib and hold down stick

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Sand bevels on each end of the hold down stick. Sand at about a 35 degree angle until the end just about disappears. Both bevels are sanded in the same side of the stick. The bevels enable the hold down elastics to be rolled up onto the stick.

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Here is the finished stick.

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Next we will make the wing rib.

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Place the rib material against a block.

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Place the rib template on the rib wood and against the block. The edges of the rib stock and the template should be aligned against the block.

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With a pencil that has been sharpened to a chisel point, draw the rib pattern onto the rib stock.

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Rough cut the rib. Don’t cut into the rib material, leave a little extra outside the line. It will be sanded to final shape.

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Here the rib has been cut close to the final shape.

This would be a good place to glue the side plates to the rib. A short bit of 1/8″ x 1/4″ could be put between the side plates and they could be sanded to final contour together with the rib. Since I added them as an afterthought, that is what I will show later. “Do as I say, not as I do.”

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Place the rib on a block and sand to the line. Keep the sanding block perpendicular to the table and keep as much of the rib as possible flat on the block. Sand a little at a time, in sections, first the front, then the middle, then the back.

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Apply glue to the flat under surface of the rib.

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Press them together, aligning them carefully, with the hold down stick extending equally in front and in back of the rib. Let the glue dry.

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Mark the wing centerline on the leading and trailing edges on the top surface. (Ignore the photos, I had to transfer the marks to the top.)

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Make sure the marks are on a line perpendicular to the wing edges.

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Apply a uniform coating of glue to the top of the rib.

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Place the rib flat on the table and place the wing on top of it, centering it carefully, then press it down.

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Press the wing down uniformly along the entire top of the rib.

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Place weights along the leading and trailing edges to hold the wing firmly in place until the glue dries.

MAKE THE REAR MOTOR HOOK AND GLUE IT TO THE FUSELAGE

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The rear motor hook can be made from an ordinary 1″ straight pin or a 1″ length of 0.020″ steel wire.

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Start by cutting the head off the pin. Hold the shaft between your fingers, place the diagonal cutter against the pin head and put a finger over the head to keep it from flying off.

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The diagonal cutter leaves a sharp chisel end on the wire. This can cut into your rubber motor, causing it to break when it is wound up. File the sharp end round. Start by filing the end down flat, then twirl the wire between your fingers as you file across the end at different angles.

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Motors can twist off a hook.  The motor will have a clockwise twist in it. With a right handed pig tail in the hook, the motor will twist itself onto the hook. Put the end of the pin in the round nose pliers at an angle where it has about a 3/32″ diameter.

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Twist the wire around the pliers to form a right handed helix. Roll up the fingers of your right hand and point your thumb out. A right handed helix goes in the direction the thumb points when going along it in the direction the fingers point.

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Bend it around to make a complete loop. There should be enough room between the end and the remaining shaft that an O-ring can easily fit through the gap.

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Bend the wire 45 degrees to raise the loop up from the stick. The center of the loop should be about  1/8″ above the stick.

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Half of the remaining straight piece is bent down at a right angle. These last three straight pieces lie in the same plane. Since this is short and hard to grip, and has a sharp end, use a block of wood to bend it.

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There is the finished hook.

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Poke a pilot hole in the underside of the stick, just ahead of the tailplane, at the appropriate angle and centered on the stick.

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Apply glue to the parts of the hook that will be in contact with wood.

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This is one place where the contact area is small and lots of glue is desirable.

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Insert the point of the hook into the stick and press it into place.

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Center it carefully.

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Press it firmly in place. It is a good idea to put glue all around the parts of the wire in contact with wood. Use a fine brush or small stick, like a toothpick. Some builders wrap and glue thread around the wire and the stick for added security.

add the side plates to the wing rib

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Sand the end grain of some 1/16″ sheet balsa.

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Align the edge of the balsa and the side plate pattern against a block. The leading edge of the pattern aligns with one edge of the sheet balsa.

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Cut out the side plate with a razor blade. Always cut into the edge of the balsa sheet. Cutting across an edge going outward will split the wood.

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Here is the finished plate. Make another just like it.

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Apply glue to the side of the rib.

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Spread the glue uniformly to coat the entire surface of the rib.

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Put the side plate against the rib. Add the other one.

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Align them carefully and press them in place.

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Squeeze them together between blocks to make sure they are flat against the sides of the rib.

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That finishes the wing. Let the glue dry.

It would have been better to make the side plates together with the rib and sand them together. I show that alternative in the next section.

Making the wing saddle with side plates

The first side plates were glued to ribs that had already been glued to wings. It is better to make the entire wing saddle as a single unit before gluing to the wing. This alternative takes the place of what was shown elsewhere.

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We start with the four components of the wing saddle, made as shown in above sections; the rib, the hold down stick and two side plates.

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Paint glue on one side of the rib.

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Press it to one of the side plates, aligning the airfoil curves. The damp from the glue may make the side plate bend away from the rib. We will press things together when everything is together, before the glue dries.

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Paint glue on the remaining exposed side of the rib.

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Place the assembly on the other side plate, aligning the bottom edges against a block and the ends with each other.

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Place a piece of 1/4″ stick alongside the saddle assembly, which is also 1/4″ high.

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Place a block over both.

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Place a weight on top of the block to hold everything tightly together as the glue dries.

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Bottom view.

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Top view.

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Place a short piece of 1/8″ x 1/4″ in the slot to support the sides as we sand the finish airfoil on the top surface.

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Place the saddle on a block, spacing it up from the table top, and sand the airfoil, keeping the sandpaper perpendicular to the table. This surface must be uniformly smooth and perpendicular the the side plates to keep the wing from being twisted.

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If I had used a shorter stick, I would not have needed to move it to sand the other end of the saddle.

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Check that it is uniformly sanded.

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It is a smooth curve without bumps or flat spots.

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Paint glue on the top of the hold down stick where it will be in contact with the rib.

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Put the hold down stick between the side plates, glued top toward the rib, sticking out equally on each end.

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Press it in place.

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Apply glue to the top of the saddle.

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Spread the glue with a bit of card.

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Put the saddle on the fuselage stick.

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I have prepared a jig to hold the wing down on the saddle as the glue dries. The stick is held between the jaws of the machinist vise. (If you don’t have a vise, you can use blocks of wood, held down with weights, such as soup cans.)  This keeps the stick vertical. On either side I have placed 1/8″ x 1/4″ sticks on top of 1/16″ sheets to produce rails with their tops 5/16″ up from the surface, corresponding to the height of the bottom of the rib. The 3″ long block will sit on top of these rails.

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Place the wing on top of the saddle and use the pin holes to align it carefully.

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Place a weight on the rails and along the trailing edge.

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Press the wing down across the entire arc and hold the leading edge down with a block.

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Place a weight on the block to hold the wing firmly in place until the glue dries.

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When the glue has dried, carefully remove the weights.

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Check the wing for warps and twist out any that you find.

Making the wire landing gear legs

You can buy prebent landing gear wire, or you can bend your own. Skills learned in bending this simple landing gear will come in handy when there is no commercially available unit. Bending steel wire is one of the important skills of any aeromodeller.

I find that the prebent commercial units often require reworking before they can be used, anyway. In particular, check that the wheel axles are not curved. If they are curved, the wheels may not spin freely.

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We start with a dimensioned, full scale drawing. You can redraw this one or you can copy, download and print this one, adjusting your printer settings to get the correct size. Actually, you can measure directly on the wire, so the important things on this drawing are the angles.

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We will make the landing gear out of 0.025″ steel wire. The total lengths of the sections of the landing gear is 9  1/4″. I prefer to have a little extra, so I started with a 10″ length of wire. The first thing to do is file down the sharp chisel edge that results when you cut wire with diagonal cutters. File it flat and then file the corners down to round off the end.

We will make the bends in sequence, starting from one end.

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We start by bending the wheel axle on the end of the wire. Put a short piece of thin tape cut from the end of the tape roll against the wire 1/2″ from the end.

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Fold the tape over the wire.

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Check the length against the plan.

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Grip the wire in the pliers right next to the tape.

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Bend the wire perpendicular to the face of the pliers. Bend it a little more than the angle you want, the wire will spring back some. Experience will teach you how much.

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Check the angle. Here we went a bit too far. It must be unbent slightly.

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Adjust and check until it is right.

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Position tape for the next bend.

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Press the tape firmly in place so it won’t slip.

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Grip the wire in the pliers. This bend is out of the plane of the previous two lengths of wire. It must be visualized in three dimensional space. Once you have figured out which way the wire must be bent, rotate the wire so the direction of the bend will be perpendicular to the face of the pliers. Push the wire to bend it. Push close to the position of the bend. If you push from too far away from the bend, you may put a curve in the wire. You want a sharp bend.

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Check the bend. This is a three dimensional object, so view it from both directions. The wire sticking up must be parallel with the central plane of the landing gear, a plane perpendicular to the drawing sheet, and it must allow the landing gear to project forward. The wire will lean away from you as seen in the photo.

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Mark next bend. This is one side of the piece that fits into a slot in the plastic propeller hanger box.

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As always, squeeze the tape tightly in place so it doesn’t slip.

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This next section will be horizontal when the axles are horizontal. I held the axle to the board to orient the assembly so i could orient the pliers for the bend.

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Bend the wire.

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This next bend is the most dimensionally critical one. The length of this section determines whether the wire will fit properly in the plastic nose piece. It must be made to exact tolerance. Put the existing edge in one slot and mark the bend position with tape. Keep in mind that the bend takes place about one wire diameter outside the face of the pliers. Place the edge of the tape about one wire diameter inside where you want the bend to be.

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This next section must be in the same plane as the previous two. Align the previous two so your eye is in the plane that contains them and make the bend, keeping the next section in that same plane.

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The completed section is in the same plane as the previous two.

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It is parallel with the one on the other side of the box. Adjust as necessary.

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Check the fit in the nose piece. It should be a snug friction fit.

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This next bend is a bit tricky. It is a compound angle bend close to the previous two bends. This next section must be the same length as the parallel one on the other side of the box. Lightly grip the two pieces of wire and slide the pliers along until it stops at the first leg. Keep the face of the pliers perpendicular to the wires. The next bend is not made perpendicular to the inside faces of the pliers, it must splay the wire out from the center as well. Refer to the drawing and note that this leg is symmetrical with the other.

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Check the bend. From the side, this leg is in the same plane as the first leg. Adjust as necessary.

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This leg is symmetrical with respect to the first one.

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Adjust as necessary.

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Check against the drawing.

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The final bend makes the other wheel axle. Mark with tape. This section is in the same plane as the previous axle and the two legs. Align that plane with your eye  and make the bend.

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Check against the drawing and adjust as necessary.

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Looks good! Mark the end of the axle where we will cut the wire.

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Cut off the excess wire.

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File away the sharp cut end.

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Slide a wheel onto one axle. The hollow part goes inside, the rounded surface faces out.

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Grip the wire so about 1/8″ sticks out beyond the face of the pliers.

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Press the end of that 1/8″ piece against a hard surface to bend it over to a right angle. This section will keep the wheel on the axle.

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Do the same with the opposite wheel. Check that the wheels spin freely.

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Press the wire box into the slots in the plastic nose piece.

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Check the fit of the nose piece on the nose of the stick. If it is too small. put the top of the stick against the top inside of the nose piece and press it in to make an indentation across the bottom of the balsa nose block.

If the stick is too small, glue on a shim of hard balsa. The prop assembly needs to be a snug fit on the stick.

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Sand the nose block down to remove the thickness that was indented. Be careful to not overdo it. Approach it gradually, with frequent test fits, until you get a tight fit.

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When you get a tight fit, press the stick all the way into the nose piece.

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This completes the fuselage assembly. We will take the propeller assembly off temporarily to put the wing on.

final assembly

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If you used tape to hold the wing panels together while the glue dried, you can remove it now.

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Pull two dental elastics over the nose and roll them about 5  1/2″ back on the stick. You can double them up if you want them to be tighter.

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Put two more on and roll them about 2″ back on the stick.

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The wing will go on between the bands.

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Place the wing on the stick and, while holding it in place with one hand, use the other hand to roll the back bands up on the hold down stick.

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Turn it around and put the hold down bands on the front of the wing.

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Put the propeller / landing gear assembly back on.

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Put a tiny bit of light machine oil on the prop shaft and bearing.

You will have made a motor according to our Motor Making instructions. This plane will use an 11″ loop of 3/32″ rubber for test flights and small field flying. For longest flights, a motor about twice the distance between the hooks is good. You will need a pretty big flying field for that, and a time with little or no wind.

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Put the motor on. The O-ring goes on the back hook. Make sure the hook is open enough so the O-ring can go in with very slight clearance.

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That completes the construction.

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Sit back and admire your work.

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We need to adjust the wing position to get proper balance. Prepare a couple of balancing supports. Stick round head pins into the ends of some blocks.

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Support the plane on the pinheads so it balances at the 40% mark on the wing, the high point, with no part touching anything else. Put a pencil mark on the stick so you can find this location again. If you use a different motor, you will need to move the wing to rebalance the plane.

We are now ready to fly the plane. Check the wing for warps and any other problems. Fix anything that is out of line before starting to fly. Read our instructions elsewhere on Winding the Motor. This plane flies best with a tiny bit of right rudder and a tinier bit of right thrust. Test fly, gradually increasing the number of turns in the motor. Start with about 150 turns in the motor and increase the number of turns by 50 on each succeeding flight if all goes well. Adjust so it climbs and descends in about 50 foot circles.

Initially flights should go high enough so you can judge the glide with the prop freewheeling.You can do that by using a motor slightly thicker than required for best time. I use a loop of 1/8″ rubber for test fights, then a loop of 3/32″ for duration flights. Adjust the rudder to get the diameter of circle you want in descent, then adjust the sidethrust, by slightly bending the prop hanger, to get the diameter of circle you want in climb.

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Happy flying!

Making TWO PART full span tailplanes

In the build above I shortened the span of the tailplanes to fit inside the flat area of the plates. As I was writing this tutorial and making my fourth Foam Plate Cloud Tramp I saw a way to cut the full size patterns on a diagonal and make the tailplanes in two parts. These instructions are generic. You can use them for either the 5  1/2″ or 6″ foam disk.

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Print out the plan to match the size you want. For the 5  1/2″ disk, adjust your printer settings to make the tailplane chord 2″. For the 6″ disk,make the chord 2  9/32″. I made one of each; one to replace the tail on an earlier plane and one for my new plane.

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Cut out the tailplane pattern a little outside the perimeter, to allow a margin for taping to the cardboard.

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We will make templates from thin cardboard. Get a piece of cardboard large enough to contain the entire tailplane, a bit more than twice as wide as the half pattern. Draw a chord line on the card. Space it a little more than half a tailplane span from each edge.

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Align the centerline of the tailplane pattern with the centerline drawn on the cardboard and tape the pattern to the cardboard at both corners.

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Tape down the tip to keep it from shifting.

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Use a push pin to poke a hole through the corner of the tailplane pattern to make a small hole in the cardboard underneath.

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Mark the opposite corner.

Also poke holes on the centerline about 3/32″ in from each corner.

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Poke holes all around the perimeter about every 1/8″.

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The holes can be a bit closer together where the curve is tighter. Go all the way around the perimeter.

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Poke a hole through the base of the arrowhead.

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Poke a hole through the base of the opposite arrowhead. These mark where the pattern will be cut in half to fit both pieces onto a plate.

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Remove the tape.

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Flip the pattern over and carefully align the center lines. You can use the push pin through the holes in the pattern to line up with the holes in the cardboard.

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Tape it down again.

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Poke through all the same holes into the cardboard.

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On this side you need to poke through only one of the arrowhead bases.

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Remove the tape.

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You can draw a pencil line through the two holes made through the arrowhead bases. This is the line along which the pattern will be cut in half. You could cut a line between these holes later without the pencil line if you prefer.

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Rough cut about 1/8″ outside the pinholes. It is easier to make a precise cut along the pattern if there is only a thin bit of card being removed.

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Cut a smooth curve between the pinholes.

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Cut the pattern in half along the diagonal line.

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Write labels on the patterns.

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Poke holes about 3/32″ in from each edge on each of the half patterns. These holes will be used to mark the centerlines on the foam parts.

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Place the patterns on the plate and arrange them so they are entirely on the flat part and there is a small gap between them.

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Draw around the patterns, pointing the pen inward. If you want, you can cut around the patterns with a sharp blade.

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Poke the four holes marking the centerline.

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Poke the holes marking the inside corners of the rudder.

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Cut out the center of the plate.

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Rough cut each part to separate them.

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Cut precisely along the inside edge of the ink lines.

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Use the straightedge to cut the base of the fin.

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Use the straightedge to cut the diagonal lines on the tailplane parts.

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Use the straightedge to cut the diagonal lines on the tailplane parts.

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Here are the cut out parts. You can see how the tailplane parts will fit together.

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Cut a slit for the lower rudder separation.

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Cut a slit for the upper rudder separation.

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Line the pin holes up with the edge of a block and press the rudder down to form a crease for the rudder hinge. The rudder should bend to the right in flight.

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Lightly sand the straight edges of the two tailplane parts and the base of the fin. They are sanded just enough to get them square and roughen the surface. Place them on a block to space them up off the table and hold the sanding block so it stays perpendicular to the table.

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Apply glue along the straight edge of one of the tailplane parts.

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Rub the two edges together to spread the glue uniformly.

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Protect your board with plastic sheet. Press the edges snugly together.

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Place weights onthe pieces to hold them flat and in firm contact as the glue dries. After the glue dries, you can peel the plastic film off the underside. The glue might still be damp under the file, so let it dry. Then you can line the pinholes up with the tailplane taper on the stick and glue the tailplane to the stick.

 

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