Sky Viewer

sky-viewer
Designer builds his dream aircraft
sky-viewer-plans

Full-size plans
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Tiled plans
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I never quit dreaming of another airplane that I would like to design. The Sky Viewer is one of those recent dreams. I was inspired when I saw a YouTube video of the Vulcan, which basically has a glass nose, giving the pilot an impressive forward view.

The Vulcan is a twin-engine airplane with the propellers on the wings and the pilot sits in front of them. I was thinking about my own full-scale aircraft pilot training roughly 14 years ago and how I struggled to know when I was going to touch down because my forward view was obstructed by the forward-mounted engine and propeller.

Of course, when flying RC, you don’t ever wonder when your airplane is going to touch down because you can clearly see when that will happen. I like to design airplanes that potentially could be upscaled and flown by a pilot. For that reason, plus the fact that it looks great, I am using a rear-mounted engine and pusher propeller on the Sky Viewer.

This model also has a nearly fully clear nose, which offers a much better view than what a front-engine airplane can offer a pilot. It also has extremely light wing loading for comfortable slow or dead-stick landings, and I kept it simple with a lot of dihedral in the wing so that only rudder and elevator are needed for flight control.

A tandem, two-seat arrangement allows for a narrower cockpit for less drag, and this airplane would be fun to scale up to full scale. The passenger also gets a truly great view of the sky through the transparent portions of the wing. Let’s get into building.

Cutting Out the Parts

Figure 1 shows a stack of parts that I cut out to build this airplane. Everything was cut with a scroll saw, and I glued the paper patterns to the balsa or plywood with a glue stick. With some parts, stack your plywood or balsa so that you can cut two at a time, such as the fuselage side panels and wing ribs. Other parts have edges cut on various angles, and you will want to set your scroll saw to cut on the angles indicated.

Building the Tail Section

Figure 2 shows the horizontal stabilizer, elevator, vertical stabilizer, and rudder all pinned and glued over the plans on the building board. Make sure that you cover the plans with waxed paper before you start gluing everything together.

When all of the pieces have dried, slot the balsa strips as indicated for the nylon hinges. Test-fit the hinges, but don’t glue them in yet. Sand all of the leading edges (LEs) and trailing edges (TEs) to a small radius. This is the most tedious part of the build, which is why you are doing it first!

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Figure 1
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Figure 3

Building the Wing

Figure 3 shows the wing being glued together. The LE, which is a 1/4-inch wood dowel, should be pinned to the building board, and all of the ribs except for R1, R4, and R5 should be glued to that dowel. Glue the TE, which is also a 1/4-inch wood dowel, to the rear of all of the ribs. Now glue the wingtips to R3 on both of the wing ends.

Figure 4 shows the 1/2 × 7-1/4 × 1/8 balsa strip glued to the top of the R3 ribs and the wingtips. Figure 5 shows the wing halves being connected. Use the plywood dihedral joiners at the front and at the back of the wing. A 3-inch piece of 1/4-inch wood dowel goes in the center of the wing, front and back, and the ends of the piece should be cut on a 10° angle to match the amount of the wing’s dihedral.

Clearly shown is a 1-inch spacer on the dihedral line on the plans. Old VHS tapes left over from the 1980s are exactly 1-inch thick. You will need to prop up the wing on both sides and the VHS tapes work perfectly.

Figure 6 shows finishing the wing’s center section. Glue in the front wing mount and the rear wing mount. At this time, R4 and R5 diagonal ribs can also be glued in, as well as the rear wing gussets. These gussets are made of 1/8-inch balsa and are stacked three high to achieve a total thickness of 3/8 inch.

Figure 7 shows the 1/16-inch plywood wing strut mounts glued to the front and rear wood dowels and R2 ribs. They should be glued at 30° downward to mate up with the struts. Also shown in this photo is one of the LED light mounts. It should be centered between the ribs and glued in high enough so that the LEDs can be visible from the front of the wing. The 45° cut should be on the upper back side of these mounts so that the mounts don’t bulge up the covering material later.

Figure 8 shows the LED light mount in position at the back of the front wing mount and exactly in the center of the wing. Note the black lines at the rear of the wing. This is a section that will be cut out with a scroll saw. The lines are 1 inch inward and 2-3/4 inch wide. This must be cut out so that the notch in the fuselage can hold the rear of the wing down.

Figure 9 shows black and green wires soldered to the white and green LEDs. LEDs only work with electricity flowing one way, so your three-cell battery holder will have a positive and a negative lead on it. The short lead on each LED should attach to the positive battery side, and the long lead on each LED should go to the negative battery side; otherwise, the lights will not light up. The wires are taped and glued to the front wood dowel. This will make your wing look much cleaner.

Figure 9A shows the top view of the wing after the top has been covered with the green and transparent covering materials. The center section that covers the fuselage has transparent covering material. I covered three rib sections with the transparent material as the airplane’s name suggests. Sky Viewer even offers the pilot and passenger a view of the sky through the wing!

Building the Fuselage

In Figure 10, you are creating left and right fuselage side panels by gluing on the plywood tailboom doublers. In this photo, the floorboard is glued to the right fuselage side panel. The rear of the floorboard should align with the notch at the bottom of the fuselage. It is held perpendicular using the VHS tape. Note that the F4 former base is further extended with a scrap piece of balsa so that it can later be better pinned to the building board.

In Figure 11, mount the motor to the plywood motor mount. Use 1/2-inch #4-40 Allen head bolts and #4-40 stop nuts on the back side to retain the motor.

In Figure 12, note that a perfectly straight line has been drawn on the building board so that you can build a straight fuselage. The floorboard is pinned to the board on the centerline that was drawn, and the left fuselage side panel is glued to the floorboard. Former F2 is also glued to the floorboard and side panel. Again, the VHS tapes are used to hold the side panel perpendicular to the floorboard.

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Figure 9A
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Figure 14

In Figure 13, the top cabin doubler is glued in at the top of the fuselage side panels. Make sure that the center of this part is exactly over the centerline on the building board using two VHS tapes.

In Figure 14, with the floorboard still pinned to the building board, glue in former F4 at the rear of the fuselage. It should be exactly at the front of the cutout for the horizontal stabilizer. Note that former F4 is again directly on the centerline and securely pinned down so that it does not move. Later, F4 will be cut from its base, but right now, that base is keeping the fuselage straight.

In Figure 15, the fuselage rear wall is being glued in place. Again, keep the floorboard and F4 pinned to the building board as you do this step. I wetted the balsa so that it would curve more easily when it is attached to the fuselage side panels. Use tape to hold it in position while it dries.

In Figure 16, former F1 is glued in position at the front of the fuselage. F1 should be glued in so that the slot is on the right side and the hole (which will later be used for wires) is on the left side. Use a piece of 1/2 × 3-inch scrap balsa and cut the front of it on a 20° angle so that it can go under the waxed paper and hold the floorboard to F1 as it dries. Note that the grooves you made earlier in the front of the floorboard make it easy to bend the plywood in a nice, upward curve.

In Figure 17, the battery box sides are glued to the nose-wheel servo mount. Their position is indicated on the plans and they create the interior of the battery box that is exactly 1-1/8 inch in width.

In Figure 18, the steerable nose gear has been bent 90° and has been cut to the length indicated. The 90° bend can be done in a vise with a tube over the wire. There is a video on the Du-Bro website showing this method. The cuts are made with a hacksaw in a vise. Not shown, but particularly important, the nylon mount for the nose wheel must have 1/8 inch cut off of the top and the bottom so that it can fit in its position.

Figure 19 shows the nylon mount screwed into position in the front of the fuselage. Next, the front fuselage doublers should be glued into place then the front cowling should be glued in. It should rest on top of the nylon mount for the steerable nose gear.

Figure 20 shows the nose piece just before I glued it to the front of the fuselage. The LED nose light mount has been glued into the nose piece and the LEDs are epoxied into the three holes grooved out on the back of the nose piece to allow the wires from the three front-mounted LEDs to come through into the fuselage. There are two holes in former F1 to allow these wires to come through. Make sure that they do so before you permanently glue the nose to the front of the fuselage.

Figure 21 shows the elevator and rudder servo mount glued into the rear of the fuselage. The rear of this part should be even with former F4 (already glued in). The photo also shows former F5 glued into the tail bottom end of the fuselage. The motor mount has been glued to the rear wall of the fuselage. The photo does not show the motor attached because I found that it is actually fairly easy to remove. Although I had you attach it earlier in my instructions, it isn’t necessary.

Figure 22 shows the nose-wheel servo mount and battery-box side panels added to the front of the fuselage, as well as the instrument panel top panel and the battery-stop piece, which prevents the battery from interfering with the nose-wheel linkage. The battery-box fillers are also glued in place from the floor up to the nose-wheel servo mount. They fill in the remaining gaps.

The separate piece at the top of the photo is the instrument panel. The instrument panel gauges will go in where the six open holes are in the front piece. The long part is a piece of 1/4-inch balsa glued to the 1/8-inch plywood piece. The balsa should be sanded to a nice curve that matches the curvature of the windshield (see Figure 25). This piece will later be screwed in place. The balsa has a large hole for the nylon screw head. The instrument panel’s top retainer, which has the threaded hole in it, is also glued in place and butts up to the battery-stop piece.

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Figure 23 shows the seats glued together but not yet sanded. After the glue has dried, sand nice, rounded corners to all of the sharp edges, except for the bottom of the seat. Note that the seat mounts are glued to the seats. For the front seat, which will eventually have a pilot sitting in it, glue the seat mounts to the back of the seat to form an X. This seat will be glued to former F2 with the top of the X in front of the former and the bottom of the X behind the former. This gives the seat a perfect angle for a pilot.

How high on the former you glue the front seat will be determined by the pilot you intend to use. On the rear seat, glue the seat mounts to the side of the seat. The seat will be later glued to the bottom floor of the fuselage behind the front seat.

Figure 24 shows the front bottom of the fuselage. The front cutout is an access panel for the three AAA batteries and the small hole in the front is for attaching this panel. The notch in this panel is for the nose-wheel servo.

A small tab is located at the rear of this access panel, which is glued in place. Glue the square mount tab to the bottom of the fuselage floorboard. It is a threaded #6-32 and will accept the nylon screw to retain this access panel.

Figure 25 shows the windshield screwed in position. It is retained with #6-32 nylon screws and the location of these holes is predrilled in the front fuselage doublers, which were shown in Figure 16. This photo also better shows the curvature of the top of the instrument panel.

Figure 26 shows the wing-mount bolts in place. Match drill through the top of the wing into the top of the fuselage, which is plywood, using a 3/16-inch diameter drill. The holes are 3/16 inch from the front of the wing and are 2 inches apart. Tap the 3/16 holes in the top of the fuselage to a 1/4-20 thread. Drill the holes in the wing out to 9/32 diameter so that you can use the 1/4-20 nylon screws to mount the wing.

The heads of these screws are nearly 1/2 inch in diameter, therefore, a flat spot on the balsa wing top will have to be grooved out so that the screw heads can rest on a flat spot. I used a Dremel tool with a 1/2-inch diameter sander to do this.

Figure 27 shows the bottom front of the fuselage with the AAA battery holder screwed in position in the nosewheel servo mount piece that you installed earlier. Use some small wood screws and drill through the battery holder between where the batteries lay next to each other. As these small wood screws come through the top side, you will have to grind off their ends so that the main drive battery does not rest on these sharp points.

Figure 28 shows me carefully drilling a hole in the vertical stabilizer. I am drilling with a Dremel tool where the nylon hinge is located, creating a hole in that hinge and not going all the way through to the other side. The idea is that the hole can later be filled with glue. When the glue dries, it creates a rivet that will keep the nylon hinge from pulling out.

When you install the horizontal and vertical stabilizers, you will want to glue them in the following order. First, glue in the vertical stabilizer, keeping it perfectly vertical as it dries. Then glue in the horizontal stabilizer and the elevator. Finally, glue in the rudder using the method I previously described.

Figure 29 shows the LEDs installed in the horizontal stabilizer. You want to do this before gluing the stabilizer to the fuselage. I grooved the balsa so that the wires could be embedded partway into the wood. The wire leads should be approximately 18 inches long so they can meet up with the other wires in the fuselage. The wires that are in the grooved balsa can simply be held in position with regular glue, although you might want to tape down those wires while the glue dries.

Covering and Final Assembly

In the wing construction, I described how the covered wing should look from above. I actually painted all of the ribs white before covering. When covering, first start at the center of the wing and work your way toward the wingtip then work toward the LE and TE dowels, again working your way to the wingtip.

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Figure 27
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Figure 32

Finally, seal the edges all of the way around. When you are done, you should be able to lay the wing flat on a table and the underside should be flat. If you get a little washout, which is the wingtips angling slightly upward at the rear, that is okay, but just make sure you have the exact amount of washout on both sides, otherwise, the airplane will be virtually uncontrollable in flight.

You can carefully twist one side of the wing slightly if needed with one hand then with your other hand, heat the MonoKote with your iron while holding the wing twisted. As you release the twist, it will hold its new shape. Later, the struts will help you achieve the right amount of washout.

The receiver will need to be linked to your radio and you will want to ensure that all of your servos go the right direction for flight control. Two servos go to your aileron control on your receiver—one to the rudder and the other to the nose-wheel servo. This is where you’ll be using the Y-connector that you bought.

On the nose-wheel servo, there is only one choice of servo direction, and that is clockwise. The servo arm movement makes the front wheel turn right, so you will need to set up your rudder servo so that clockwise also makes the rudder turn the airplane to the right. When you install the ESC, you will want to make sure that the propeller turns in the right direction.

Although this might seem obvious, every propeller blade has a curved side and a flat side. Make sure that your curved side faces forward or you will lose roughly half of the thrust. If your propeller turns the wrong way and the airplane wants to go backward, simply change any two of the wires from the motor to the ESC, and then it will go the right way. I did not install a switch for the LED lights, so when the three batteries are in the holder, the lights are on.

The bottom access panel holds the batteries in place when the nylon screw holds the access panel in. Always turn on your radio first with the throttle stick in the back position before connecting your drive battery. Make sure that the stick does not get bumped forward while you are securing the access panel.

The pilot is a heavily modified doll that I found at Walmart. I adjusted the seat and the pilot so that its feet could span the battery box. I also added a small seat-mounted flight-control box made from scrap balsa block and a toothpick.

Figure 30 shows where the covering material should be cut to allow you to glue on the fuselage strut mounts. The strut mount gussets should be glued in at this time, which puts the strut mounts upward at a 35° angle. After these parts have been glued to the fuselage and the glue has dried, add green covering material on these parts and lap it over roughly 3/8 inch onto the fuselage. This will provide extra strength to adhere to the fuselage sides.

The strut construction is essential. Cut the 3/16-inch wood dowels to the length shown on the drawing (sheet 2). You will need to cut two front struts and two rear struts. In a drill press, carefully drill a 3/32-diameter hole centered in each end of the dowels and drill them 5/8 inch deep. I found that it was easier to push the dowels up into the drill.

Cut eight pieces of the #2-56 threaded rod to 1-1/8 inch in length. Epoxy these pieces into the holes you drilled in the end of the dowels. When the epoxy has dried, cover the wood dowels with green covering material.

Install the wing on the top of the fuselage with the 1/4-20 nylon screws. The struts can be added at this point using the Kwik-Link clevises to connect the wing to the bottom of the fuselage with the struts.

You should be able to do so by adjusting each clevis to get the washout exactly the same on the left and right wing halves. The right amount of washout is roughly 1/4 inch.

Figure 31 shows the link from the front nose-wheel servo to the nose-wheel arm. This part took me several tries to get it perfect, and it is impossible to rebend the steel rods, so you might have to make a few to get it right.

Figure 32 shows the link in position connecting the servo to the nose-wheel arm.

Flying

This airplane uses the same wing that my Sky Springer model did from the October 2020 Model Aviation issue. decided that this model should be similar in flying characteristics as the Sky Springer, and it is. Because there is not a lot of propeller clearance to the ground on takeoff, I would recommend flying from a paved runway. That is the only way my prototype has been flown.

Taking off from grass might be possible, but you could have to mow the grass before takeoff. The wing allows for nice, slow flying, and even with rudder-only steering, it will make beautiful, smooth turns.

So far, all of my flights on the prototype have taken place in fairly calm conditions with no more than 3 mph wind. The airplane will perform a loop, but it requires flying slightly downward to gain speed first. Loops are best done large and gentle because a tight loop puts more stress on the wing. When it’s time to land, throttle back, and you won’t have to do a long landing approach. Just flare a bit before touchdown and have fun!

two of the authors music students display
Two of the author’s music students display the completed airplane. This shows that the pilot has a great view from the cockpit.
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