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Bill of Materials
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Fifteen years ago, my original SkyCrawler design was published in Model Aviation magazine. At that time, LiPo batteries and brushless outrunner motors were unavailable and video cameras were still big and bulky. As the new batteries and brushless outrunner motors became accessible, and HD (high-definition) video became available in small point-and-shoot cameras, I decided that my old SkyCrawler design needed an update.
I changed to a lower landing gear position on the model, so a camera wouldn’t hit the ground if I installed one. This also allows takeoffs from grass fields that might not have been mowed for a while.
In my updated SkyEye design, I use a brushless outrunner motor, and a 3S 1,300 mAh LiPo battery. This airplane has been a lot of fun to fly, and hand launching is unnecessary because of the model’s big wheels and high stance.
The video camera that I carry on the SkyEye is a 1.5-ounce Polaroid Cube (polaroid.com/cube) camera that records the flight in 1,080p HD. I thought some of you might enjoy doing what I have been doing—shooting aerial video. This videography is just for fun, and AMA rules need to be followed at all times.
The SkyEye is fun to fly, even without an attached camera. It will take off from any larger grass field and lands nicely on the same. Let’s build the SkyEye.
First, cut out all of the pieces for the entire airplane. The oak suspension mounts should have the holes drilled in them before they are cut to shape. As noted on the drawing, some of the parts require two, four, or even 16 of the same parts to be built. Stack balsa or light plywood, and carefully glue around the edges, then cut out the multiple parts as noted. I used a glue stick to put the patterns on the wood.
The horizontal and vertical stabilizers can be glued and pinned to the building board or a piece of drywall and then allowed to dry. Waxed paper should be laid over the plans so the pieces don’t stick to the plans. When the pieces have been removed, slot the edges for the hinges after you mark the centerline in the balsa using a T-pin. Test fit the hinges into the slots.
The ribs of both wings are glued to the LE (leading edge) and TE (trailing edge) wooden dowels. Pinning the front dowel to the plans before gluing and pinning the front of each rib to the dowel works well. Then, lay the rear dowel up against the rear of all of the ribs. Put a dab of glue into each spot where it will contact a rib, and then roll the rear dowel forward to glue it to all of the ribs at the same time. Also in this step, add in the diagonal ribs. When the wings have dried, add the wingtip support pieces to the outer three ribs.
The ribs of both wing halves have been glued to the LE and TE wooden dowels. Pinning the front dowel to the plans first, and then gluing and pinning the front of each rib to the dowel, works well.
The wingtip pieces will need a bit of sanding as they are joined. Let the glue dry between each step of the five-step operation.
Pin the left wing to the building board, and make sure the wings touch each other at the end of the dowels. Put a 2-inch spacer 51/2 inches from the center of the wings under the right wing to space it up for 20° of dihedral (I used two VHS tapes). When that has dried, glue in the four light plywood wing mounts, then sand the wingtips on both sides.
The wing halves are glued together with the dihedral joiners. Pin the left wing half to the building board, and make sure the wing halves touch each other at the end of the dowels. Put a 2-inch spacer 5.5 inches from the center of the wing under the right wing to space it up for 20° dihedral.
This is a good time to glue in the strut mounts, and use the 1/2-inch thick balsa strut mount jig to get the correct angle. Make sure that you install the #2-56 blind nuts into the strut mounts before covering the wing, because it will be impossible to do so later.
For the fuselage, note that the first of the 1/4-inch dowels that connect the firewall to the oak suspension mounts have 1/16-inch scrap spacers under them. The firewall itself has 1/8-inch spacers beneath it.
The two nose pieces are glued to the firewall, and the motor mount is glued to the nose pieces. Put the nose piece on the right side as indicated on the drawing to provide some right thrust, which is helpful on takeoff. The firewall should be spaced up with a 1/8-inch-thick piece of scrap wood. Add the ESC mount when the nose pieces have dried to the firewall.
Cut the 7/16 dowel to proper length and flatten the rear with either a sander or a scroll saw so that you have a flat area to glue on the tail mounts. Glue them on along with the tail skid support.
To keep the firewall perpendicular to the fuselage stick, I used the VHS tapes and a crack in my flooring. The alignment tool holds the rear of the fuselage at the elevator servo mount location.
The 1/8-inch plywood pieces (number four), are glued in place. I found it easiest to hold the entire fuselage vertical for this step. When that has dried, glue in the 1/8-inch plywood strut mounts on both sides.
Next is the camera mount. The vertical balsa support pieces should be spaced exactly 13/8 inch apart from each other. Epoxy in place the small galvanized plate that accommodates the Polaroid Cube’s magnetic mount. The 1/4-inch diameter hole in the center can accommodate a small point-and-shoot camera such as a Sony Cyber-shot (Sony.net), which can shoot 1080p HD video. It should be noted that the Sony camera weighs roughly 41/2 ounces, whereas the Polaroid Cube is 11/2 ounces.
The SkyEye Mini’s performance will vary depending on the camera you choose, and the takeoff distance is considerably longer with the heavier camera.
The wing mounts should be glued in at an 111/2-inch spacing, as shown on the drawing. It is easier to first glue the wing mounts together as a subassembly. For the battery, I glued in a 1-inch-long, 1/4-inch dowel into the front hole to anchor an elastic to retain the battery in flight. This entire battery mount can be glued on top of the 7/16-inch dowel fuselage stick, to attain the correct CG (center of gravity) in the range shown on the drawing.
Only one battery mount is required. The battery is used as a jig to support the side pieces as they dry. A 1-inch piece of 1/4-inch dowel was glued into the front hole.
I measured my CG to go with the lighter-weight Polaroid Cube. When I attach the heavier camera, the CG is moved forward slightly, but it does not seem to hurt the model’s flying qualities. Don’t do the final gluing of the battery and its mount until all of the other components are in place.
Covering and final assembly include gluing the 3/16-inch gussets to the top of the horizontal stabilizer. This will allow the vertical stabilizer to be glued in place after covering.
The landing gear, made from 1/8-inch steel rod, needs to be bent and attached. It can be bent with a hammer and a vise, but a more precise method is to use a press brake. I don’t own one, so I took the steel rod to a local machine shop, and the proprietor bent it for me.
When the landing gear is attached to the fuselage with nylon ties, the front oak pieces will need to be grooved with a Dremel tool, to stabilize the formed landing gear. Also glue in a 1/8 x 1/4 x 41/2-inch plywood piece on top of the landing gear and attach it to the 1/4-inch dowel.
Attach the wheels, and retain them with the 1/8-inch wheel collars. Using nylon screws, mount the wing to the fuselage by drilling and tapping the oak wing mounts of the fuselage to #10-32 thread. The 3/16-inch wood dowel struts should be built at this point. Place a 1/16-inch drill bit so it is coming out of the drill no more than 3/8 inch to prevent it from wobbling. Drill the dowels to a full 3/8-inch depth. Now the #2-56 threaded rods (cut to 7/8-inch length) can be inserted into the dowel struts, and epoxied. They should stick a 1/2 inch out of the dowel.
The front of the fuselage has the battery mount and ESC secured with a nylon tie. The landing gear, made from 1/8-inch diameter steel rod, has been bent and put in place.
After all of the outside edges have been sanded smooth, the structure is ready to be covered. Cover the wings first. Only the upper surfaces are to be covered. This creates a lot of drag, but it also makes the airplane slower and easier to fly. Make sure you wrap the MonoKote at least three quarters around the LE dowel and the TE dowel so it will stay on during flight.
When the wing is covered, the dowels will bend upward slightly. Try to have the same amount of bend on both sides. The nylon hinges, which attach the control surfaces, should be epoxied in place. I drilled 1/8-inch diameter holes partway through the balsa and through the nylon hinge, and filled the holes with epoxy so that no epoxy jams up the hinge operation.
Solder the connectors to the ESC wires and battery. Attach the servos with the extender wires. The ESC and receiver can be held in place by wrapping electrical tape around the fuselage stick. Use the gauge supplied with the plans to achieve the correct amount of elevator and rudder travel.
The struts are attached to the strut mounts using the adjustable ball joints. Make sure that the TE is higher than the LE at the outer part of both wings. This provides some washout and will make the airplane easier to fly. Try to make the amount of washout equal on both sides. When the model is completely assembled, hold the battery and its mount with elastic bands and check the CG. When the correct position of the battery is determined, glue the mount in place.
Probably the best thing about SkyEye is its flying qualities. The aircraft will take off from nearly any grassy or hard surface. I prefer to take off from grass because the tail skid drags. This helps keep the airplane straight without having to use a lot of rudder. If you take off from a hard surface, you will need to use more rudder correction.
Flying is simply fun and relaxing. The SkyEye Mini will do loops from level flight. If you do fly to take video, I found that the best video comes when the airplane is flying straight and level.
Be careful not to fly it too far away when shooting video, and make sure to get permission to fly over certain areas. Golf courses (after or before hours) are perfect for this. I always fly where there won’t be people, and I think this is common sense.
When landing, cut the throttle and the airplane will quickly drop. As you get close to the ground, feathering up with elevator will probably not be enough for a smooth landing. You will need to add a touch of throttle to grease the landing.
I promise you will have fun!