To be featured in the upcoming June 2014 issue, the Sky Skooter construction article by Clark Salisbury shows what you can do if you have a good imagination.
Before we begin building, I need to explain my motivation for designing an RC plane like Sky Skooter. I have always been intrigued by the idea of taking my wife, and a couple of kids or friends to a distant place, (500 or 600 miles). It would be fun to do that faster than I could in a car, and be able to see the scenery from above, and not have to follow large trucks getting to that destination. The Cirrus, the Lancair, and a few other planes seem to fill that need, at a decent 200 mph or better. So, yes these 200 plus horsepower light planes with four seats have intrigued me.
With that in mind, I present to you the Sky Skooter, a 1/9-scale version of what I think would be a great way to get around, inspired by full size planes, both certified and homebuilt, already on the market.
Cutting out the parts:
Before you start glueing any parts together, cut out all of the pieces from the plans, by using a gluestick, and attaching the paper cut pieces to the wood. In some cases, such as the fuselage sides, and all of the ribs, cut the pieces out, after you have layered two pieces of wood together. Just be careful not to put glue only around the outside of the cutouts. Most of the parts have been put on the drawing separately, into a cutout pattern, but such is not the case with the rudder and elevator. You will need a scroll saw to cut all of the pieces.
In figure 1, I am showing you the trickiest piece that you will be cutting. It is the piece made from 2 inch wood dowel, that when cut will become the top part of the engine cover. Draw a 5 inch line exactly along the center of the dowel, after cutting the dowel to 5 inch length. Now, gluestick the template exactly to the top of the dowel, along the centerline you have drawn. Now, rotate the dowel 90 degrees, and glue on a couple of scrap pieces to the bottom of the dowel, so that the dowel can be held in that position, as you put it through your scroll saw, to cut out the part.
Tail Feathers and seats:
As shown in fig. 2, the horizontal and vertical stabilizers have been pinned to the plans, and glued. Use wax paper over the plans so that the parts do not stick to the plans. After you have glued these assemblies together, take some time and sand the seats to shape, and then glue the seat supports to the seat backs, and to the seat bases as shown in fig. 3.
OK, now that you have done that, the horizontal and vertical stabilizers should be dry, so you can unpin them, and sand the edges to a nice 3/16 radius. Also, you will need to sand down the ¼ dowel to the thickness of the elevator. This is a good time to cut the slots into the rudder, elevator, and the stabilizers. Test fit the hinges into the slots, but don’t glue them in yet.
In fig. 4, the wing structure has been started. First, cut the ailerons from the trailing edge, if you haven’t already done so. Now, slot the ailerons, and the trailing edge for the nylon hinges. I found that I had to cut the nylon hinges down a bit, to fit in the ailerons, without coming through the balsa. Sand the edges of the ailerons, so they can move up and down. Now, test fit the hinges, and leave them in, but don’t glue them yet. Pin the trailing edge onto the plans, and glue in the 1/16 balsa sheeting on the bottom rear section of the wing, both sides, and glue in the landing gear mounts, made of 3/16 ply.
In fig. 5, additional steps have been taken. Pin the bottom 3/16 square spar to the building table. Now glue the 1/16 sheeting which is the front bottom section of the wing to the 3/16 spar. Now, glue in all of the ribs, but ribs 1-3 should only be glued to the 1/16 sheeting where the ribs are flat on the bottom. When the ribs are in place, glue the upper 3/16 square spar to the top of all the ribs.
In fig. 6, the web pieces, W1-W10 have been glued in place which connects the upper 3/16 spar piece to the lower 3/16 spar piece.
In this step, as fig. 7 shows, glue the ¼ dowels to the front of all of the ribs on both side, to form the leading edge. Now, push the aileron servos through the aileron servo mounts, but do not attach them yet, and don’t glue the mounts in place yet. Just let them be lose between R3 and R4 as shown. Push the aileron wires thru the holes in R1, R2, and R3. Glue a small piece of scrap balsa to the hole at R1, to make it smaller, so that the aileron wires can’t accidentally be pulled through. Now, glue the upper 1/16 sheeting to the rear section of both wings.
In this next step, the front upper balsa sheeting has been added to both wings, and the 1/16 x ¾ balsa strips to the top of the leading edge as shown above in fig. 8.
Fig. 9 shows the lower balsa sheeting pulled up to the leading edge, glued, and held in place with masking tape.
Fig. 10 shows the wings joined together. Use VHS tapes, which are exactly 1 inch thick, at the dihedral lines on the wing plans. Now pin R1 on both sides, and add the dihedral joiner, which will hold the spars together. Also, sheet the bottom section of the wing behind the dihedral joiner.
In fig. 11, the front wing mounts have been glued to the front of the wing, and the ¼ dowels, are also glued in place. The dowel spacing can be held exactly correctly, by using the F4 doubler as shown, but of course, don’t glue the dowels to the doubler.
This is the last step to finish the wing before covering. In fig. 12, it is shown that the sheeting has been competed on the bottom of the wing. On the top of the wing, use the 6 inch wide, 1/16 balsa to sheet as far back as shown. Notch out for the oak wing mounts, and add a notch at the front the same width as the battery, and notch 1 inch deep. At the rear top of the wing, just add a 1 inch wide piece of 1/16 balsa as shown.
When all the sheeting has dried, sand the wingtips to match up with R11 rib, and sand the leading edge of the wing. Also sand off any rough corners, etc. The aileron servo mounts can now be glued to R4, and the front of the trailing edge. They mount flush with the bottom of the wing.
Fuselage and Wheel Pants
Notice that there are differences between the left and right fuse sides. Glue on the elevator and rudder servo mounts to the inside of the fuse sides. Also, you will want to turn your building board into a fuselage alignment jig, as shown above in fig. 13. Just glue in scrap balsa triangles, 3×4 inches, along the top view of the fuselage on the plans. Glue in a triangle wherever there is a former. This jig will be used thru the entire building process to keep the fuselage straight. Also, at this time, mount the engine plate to F1, with the blind nuts, and the steerable landing gear to F2, also with the blind nuts, it will be very difficult to do it later.
Fig. 14 shows the wheel pants clamped together. You will want to make two wheel pants with the plywood on the right side, and one with the plywood on the left side. When the glue is dried, and clamps have been removed, trace the cutting pattern on the top of all three wheel pants, so that they can be cut to this shape with your scroll saw. Now, sand the wheel pants to a nice smooth shape.
In fig. 15, add formers, F9, and also F7. I found that clamping them at the top, and then using small balsa wedges at the bottom will hold them nicely in place against the jig, as the glue dries.
Fig. 16 shows that F8, F6, and F5 are glued in place, again using small balsa wedges and clamps.
Fig. 17 shows that the instrument panel, F4 is now in place, and the floorboards are also glued in. Lastly, glue in the canopy rim stiffeners.
As shown above in fig. 18, the F3 former is glued in place, and F2, which is the landing gear mount, also, F1, the engine mount, and the pine nose piece. Before you glue in the nose piece, mount the engine, so that the nose piece can be centered properly. I covered the motor with tape, because a lot of sanding will be done around it later. I actually glued each on of these in one at a time, and let glue dry between each piece. Now, glue in the 1/16 pieces over the instrument panel, connecting to F3, and also the rear upper fuse covering pieces, also made of 1/16 balsa. Both of these parts must be bent, and you can do much easier, if you wet both sides of the balsa first. Painters tape works well to hold them in place.
Fig. 19 shows the motor cover built, and pinned together till it dries. Once again, wet the 3/16 balsa both sides to be able to bend it into shape. The formers, F0, and F3A will hold the balsa to shape. Also, in this step, glue in the oak pieces between F1 and F2 in the fuselage. When dried in place, these pieces need to be drilled and tapped to #6-32, so that the nylon screws can be used to retain the engine cover later. Later when you are sanding the engine cover to shape, install the screws to hold it in place.
Fig. 20 shows the fuselage turned upside down. Use the same jig built onto your building board to hold the fuse in place, and glue in the right and left sides of the fuse bottom front section. Also glue in the rear bottom piece. When those have dried, glue in the front center bottom section, along with the air scoop front piece, and two side pieces. On the rear bottom, glue in the mid-section piece, and the two 3/16 balsa filler pieces.
Fig. 21 shows the gussets for the rear wing mounts in place, against the bottom of the floorboard, with the wing mount glued in place. Make sure that the wing mounts properly at this point, you may need to sand a bit, or drill thru the front mounting holes, in F4 for a good fit. Although not shown, this is also a good time to glue in the rear window deck piece, made from 1/16 balsa, and the oak rear window, and oak front windshield mount in place.
Fig. 22 shows the 3/8 plywood canopy formers, C1, C2, and C3 glued in place to the fuselage sides. To achieve the exact correct location for these pieces, use the vacuum formed windshield and rear window to check and make sure that they will fit correctly once the formers are in place. The ¼ inch balsa roof pieces have been glued in place, and when they have dried, sand them to match the formers, C1, C2, and C3 along the top of the roof.
Fig. 24 shows the front wheel servo attached to the front wheel control arm. The steel connecting rod will need to be bent at both ends, and put into the hole on the servo arm to achieve the steering travel you want. In the photo, the front wheel servo has been painted already, to match the interior color I chose.
In fig. 25, the battery supports have been glued in place. The front and rear sports are glued as shown, then add a piece of ¼ balsa to the top and bottom of the floorboard, these pieces should be ½ x 1, and when they have dried to the floorboards, drill a ¼ dia hole thru the two pieces and the floorboard. A 2” long dowel has been put into a ¼ dia hole thru these two pieces. Note that the dowel is not glued in. It is to retain the battery, and is held in place with friction.
Fig. 26 shows the electrical parts attached to the bottom of the floorboard. I used epoxy to attach the receiver, and nylon ties to attach the ESC to the bottom of the floorboard. It is a good idea to reinforce around the holes you drill in the floorboard, with scrap balsa. Note the battery location. This location worked for me, to get the center of gravity (CG) right, but you may need to slide the battery forward or rearward, before glueing in the battery retainer pieces. Use the extension wire on the receiver, to be able to attach the aileron servos. Also, use the wire Y connector to bring the aileron wires together. The other Y connector is for attaching the nose wheel servo and the rudder servo together. A hole has been put in the bottom of the wing to attach the battery when getting ready to fly, and also for battery charging, without having to remove the wing. The hole is important also, because it allows air to flow under the floorboard, to keep the ESC cool.
Flying the Plane
I had my friend and test pilot Dave Stewart fly the plane for the first time, while I shot video. Our local club, Bridgerland RC Club, has a 700 x 50 foot runway, and we tested with snow piled pretty high on both sides. I believe the plane used about 100 feet to take off, and it lifted very smoothly. It is important to keep the CG as shown on the plans, and the wheels located as shown. Anyway, the plane flew very smoothly in the cold winter air.
The flight lasted about 7 minutes, and when I charged the battery back up, noticed than it had only been discharged about half way. Landing should be kept at a good speed, and the SkySkooter has a pretty long run out. Just enjoy, this is a fun plane to fly. Dave’s only comment was that the plane would be more of a pylon racer if I had installed a four cell, instead of a three cell li-poly battery. If this is your first plane, do some flight training on a computer simulator first, as this plane is definitely not a trainer. Personally, I thought the speed of this plane was just about right.
Sky Skooter Bill of Material
Item Quantity Description Available
1. 2 1/4” dia round hardwood dowel, 36” long Hobby Store
2. 4 3/16 square balsa strip, 36” long Hobby Store
3. 2 3/16 x 4 x 36” Balsa Sheet Hobby Store
4. 1 3/16” Aircraft Plywood Sheet 6” x 24” Hobby Store
5. 1 1/8 Aircraft Plywood Sheet 6”x 24” Hobby Store
6. 2 1/16” Balsa Sheet 4”x36” Hobby Store
7. 2 1/8” Balsa Sheet 3”x36” Hobby Store
8. 2 1/16” Balsa Sheet 6” x 36” Hobby Store
9. 1 ¾” Pine, 3” x 6”, min., or 1x4x4ft. Pine @lumber store Hobby Store
10. 2 Trailing edge, balsa, 3/8 x 1 ½ x 36 Hobby Store
11. 12 in. 1/16” diameter steel rod (servo connectors) Hobby Store
12. 2 pkg Medium Control Horns, (for 1/16 pushrods) Hobby Store
13. 1 .090 Alum sheet 6×12 (for landing gear) Machine Shop
14. 1 #6-32 x ½ Nylon Bolt, countersunk head (front cowling attach) Hobby Store
15. 2 #8-32 x 1 Machine Screw (for mounting wheels) Home Depot
16. 4 #6 Wood screw ½ long (for mounting landing gear to wing) Home Depot
17. 4 #8-32 Stop Nut, or Elastic Stop Nut (wheel mounting) Home Depot
18. 1 10×6 Prop. (electrics only) MAS1060NE Horizon Hobby
19. 1 3 Channel Radio (minimum), w feather light Receiver 800-338-4639
20. 3 Spektrum Micro Servo, Horizon #SPMSA4010 “ “
21. 2 Hitec Micro servo, HS-55, Horizon #HRC31055S “ “
22. 1 Speed Controller, 40Amp #EFLA1040L “ “
23. 1 E-flite 25BL, Brushless Outrunner Motor #EFLM4025A “ “
24. 1 E-flite 2100mah Lipoly Battery #EFLB21003S “ “
25. 2pkg. Medium Nylon Hinges DuBro cat. No 116 “ “
26. 1 set Control Horns, Nylon large DuBro#105 “ “
27. 1 DuBro Steerable Nose Gear DuBro#153 “ “
28. 1 Pkg. DuBro 5/32” Plated Brass Wheel Collar “ “
29. 1 DuBro 2” Spinner, DuBro#272 “ “
30. 2 pkg. DuBro 2.5”Micro Sport wheels, DuBro#250MS “ “
31. 2 Servo extender wires 9”, Horizon #SPMA3002 “ “
32. 2 Servo Y harness, Horizon #JSP98020 “ “
33. 2 rolls Covering (I used Hanger 9 Ultracote Transparent Blue, and White) Hobby Store
34. 1 piece Transparent covering ( to cover side windows) 4×18 Hobby Store
35. 1 can Spray Paint, latex enamel to match monocote color Paint Store
36. 1 set Battery connectors of your choice, male and female Hobby Store
37. 1 Wood dowel, 2” diameter, need only 5” Lowes or Home Depot
38. 2 Balsa block, 2x3x12 long Hobby Store
39. 2 ¼-20 Nylon Bolt, ¾ long Home Depot
40. 1 ¾ x 2 x 12 Oak Block Home Depot
41. 1 3/8 Aircraft Plywood, 6×12 Hobby Store
42. 1 ¼ Balsa Strip 3 x 36 Hobby Store