This is a continuation of a separate article where I demonstrated the flying go-cart called the SkyCart. In this article, I quickly take you through the construction so you can build one yourself if you like.
Video Breakdown:
Intro - jump
Part 1. How It Works - jump
Part 2. Building It - jump
Part 3. Foam Construction - jump
Part 4. Tire Construction - jump
Part 5. Servo and Control Installation - jump
Part 6. Final Steps - jump
Part 7. What I Might Do Differently - jump
Intro
1. I just built the flying RC go-cart called the SkyCart.
2. If you haven’t already, be sure to check out my flight video.
3. In this video, I’m going to go through some of the construction details for the SkyCart.
4. Note, these are free plans available on RCGroups and it was created by users leadfeather and motorhead, so I can’t take any credit. Check the video notes for the link to the thread.
5. In this video, I’ll cover the materials I used, but not necessarily what’s recommended in the thread. However, I’ll try to point out the differences as I go along.
6. There are 7 parts to cover in this video. We’ll cover how the SkyCart works, what you need to know get started on building it, go over the Foam and Tire Construction, cover servo and control installation, talk about Final Steps and then end with what I might do differently.
Part 1. How it Works
1. First, let’s discuss the basics.
2. The SkyCart is a 4-channel EPP foam-based RC plane/go-cart.
3. The 4 channels are throttle, rudder and elevons (which work as elevators and ailerons).
4. The high angle of attack on the motor, combined with a rectangular horizontal surface, helps provide lift.
5. Two side pieces and the center vertical stabilizer provide stability.
6. The rudder and elevons are used for turning on the ground and in the air.
7. To make turning the most effective on the ground, you typically turn the rudder in conjunction with the elevons.
8. When on the ground, the elevator part of elevons don’t do a lot, except help launch the SkyCart into the air with a quick elevator stick up then down motion. You can also get a take off by driving on bumpy ground, driving into the wind or going over a ramp, like the pitcher’s mound at a baseball field. Taking off from a flat parking lot is doable, but more challenging.
9. When in the air, the elevator works with typical pitch up and down.
10. Because the SkyCart uses elevons, you need a radio transmitter that does delta (aka elevon) mixing or buy an inexpensive delta mixer.
11. I would recommend the SkyCart for any first time flyers. The design reminds me of a nutball. It’s simple to fly and forgiving, just be sure to keep your flight level using your aileron or rudder control.
Part 2. Building It
1. To build it, it helps to have some RC and foam scratch building experience, but it’s good for first-time builders too.
2. I’ll put links to the items I used in the video notes.
3. Don’t worry if you don’t have the exact items here. Just improvise or use something close.
4. Mine weighs about 13.5 ounces, but the thread suggests a 8 ounce weight, but mine still flies fine even though it is heavy. I’ll suggest some lighter options along the way, if you’re concerned about weight.
Part 3. Foam Construction
1. Download one of the character graphics from the RCGroups thread, print it out, tape together the pieces and cut around the border. Note, you’ll have two sides to the graphic. Also, download, print and cut out the 4 tire graphics.
2. Using a new hobby blade or utility knife, cut out your foam pieces using these dimensions. You’ll cut out the main wing and 2 side pieces. I used 9mm 1.3# EPP foam. Don’t cut out the piece for the vertical stabilizer yet.
3. For the main vertical stabilizer, spray the back of one of the character printouts with spray adhesive, glue it onto a foam sheet, then cut out around the border. Note, for more stability, you can add tabs in the bottom of your vertical stabilizer that can fit into notches later. Spray the opposite side of the foam sheet and carefully attach the other character printout side.
4. For front support, on the bottom of the main wing, cut a slot for a 3mm carbon fiber tube, a ½” back from the leading edge. Hot glue it in.
5. Repeat the same for the rear support tube, but this time cut the slot a ½” in front of the elevon hinge line.
6. For rear axles I used 6” 3mm carbon fiber rods. Tubes work OK too. If your tires are wider than 1”, you’ll need to cut carbon fiber tubes that are longer than 6”. Cut slots on the bottom of the elevons for the rear axles 2” from the tail edge of the elevon. If you’re using the 1” tires you’ll want to have 1-3/4” sticking out.
7. Cut the hinge lines for the elevons on the back of the main wing and the rudder on vertical stabilizer. You want to cut each side at an angle around 45 degrees. Doesn’t have to be exact, it will still work. Notice, I use a metal straight to get an angle.
8. Rub some welders or beacon foam-tac glue on the edge of the hinges, let them dry 20 seconds, then push the hinges edges together to allow them to stick. You can reinforce the hinges with straping tape if you wish. You just need to spray it with adhesive first.
9. Now is a good time to paint the pieces if you wish.
10. Hot glue the side pieces to the main wing
11. To make a front axle, measure 2” from end of wire and make a 90 degree bend, measure 1-1/2 more inches and make another 90 degree bend in the opposite direction, but within the same plane. You should be left with 2-1/2” on the end. Slide the 2.5” end into front carbon fiber tube support. Repeat for other axle. Note, if you are using tires wider than 1”, you’ll need to increase the 1.5” measure I mentioned.
12. Cut a 1” x 1-5/8” piece of plastic or thin plywood to secure the axle in place. Drill a hole in the plastic about 1/4” from the bottom to allow the axle to fit through.
13. Place the axle inside. With axle perpendicular to the main wing, glue the plastic in place. Repeat for the other axle.
14. In the front of the vertical stabilizer, cut out the slot where the stick motor mount will go. Solder bullet connectors to your motor and ESC if they don’t have them already. Attach the motor to the mount. Hot glue the motor mount into the slot.
15. Use hot glue to attach the vertical stabilizer to the center of main wing, making sure they meet at the front. If want, you can create notches in the middle to lock the pieces together.
16. Hot glue motor mount supports each side of the motor mount.
Part 4. Tire Construction
1. Now for Tire Construction.
2. I used 1” thick foam from Home Depot to make my tires. The forum suggests using EPP foam. The tires are 4” in diameter. I used a 4” hole saw to cut them, but you could just cut them with sharp blade. Use a marker to marker the center of the hole, you’ll need to know that later. Cut 4 tires.
3. Cut eight 2” circle discs from plastic gift cards or old credit cards. Drill holes in the center for the size axles you need, making the holes just slightly little larger than the axles. These will be the wheel hubs. Note, the front axles are smaller than then rear ones.
4. Cut notches in the sides of the disc and bend them over 90 degrees.
5. Push the discs into the center of each tire, lining the center holes together. Hot glue them together. Repeat for other side of tire and for all 4 tires.
6. Spray paint tire black if you wish.
7. Cover the tread of tire with black duct tape for durability.
8. Hot glue the printed tire covers, one onto each tire. Make sure the center of cover is in the middle of the hole.
9. Cut a 4mm long piece of fuel tubing just large enough to fit over each axle. Slide the tubing all the way against the main wing. Use CA or Super Glue to glue in place. You can also use a glob of hot glue if you don’t have fuel tubing.
10. Put a tire on each axle.
11. Cut another 4mm long piece of fuel tubing just large enough to fit over each axle. Slide one onto each axle and glue into place. Make sure to leave a little room for wheel to turn. You can also use a glob of hot glue or an actual wheel collar to keep the wheel on.
Part 5. Servo and Control Installation
1. Now for servo and control Installation.
2. Plug each servo and the ESC into the marked ports on the receiver.
3. Turn on your transmitter and plug in the battery into the ESC.
4. Center all your control surfaces. Turn on delta mixing on your transmitter or if you don’t have delta mixing, hook up a stand-alone delta mixer into the marked elevator and aileron ports and plug the elevons into the other end of the mixer.
5. Determine servo mount locations and trace around them with a pen. I installed my elevon servos 4” back from the leading edge and 1” from the side edges. I installed my rudder servo about 3” in front of the elevon hinge line.
6. Attach servo arms to servos with screws.
7. Cut servo location a little smaller than the outline mark made. Don’t glue it in yet, just put the servo in the slot.
8. Install one end of your control rod into the servo arm. Let it run straight back to the control surface. Mark a line where it crosses. Put a control horn on this line and move it to where it just reaches the hinge line. Cut a shallow slit in the foam and put the control horn in. Don’t glue it in yet.
9. Cut control rods to length and attach the other end to the control horn.
10. Test servo movements and confirm they move in correct directions. Reverse the channels if necessary.
11. When you are happy with the movements, hot glue the servo and control horn in.
Part 6. Final Steps
1. Determine placement for your receiver, ESC and battery. Once you do that, I recommend you attach each with Velcro.
2. Install the ESC on right side of plane, on the side. I installed mine here.
3. Install the receiver on the left side of the plane. I installed mine here.
4. Now the CG is about 5 to 5-1/4” back from the leading edge, which is important for the next step, battery placement.
5. It’s a good idea to be ready to move your battery forward and backward, to help meet the CG of the plane. I had to put my battery all the way in the front right below the battery and I cut out a slot beneath the motor because I had more weight in the back of my plane. If yours is lighter, you probably want to put the battery on the right side of the plane. You can install a longer strip of Velcro so that you can move the battery forwards and backwards.
6. Install your propeller and prop saver if you have it.
7. Turn on your transmitter and plug in the battery into the ESC.
8. Test all control surfaces move in right direction. Rudder stick right, moves rudder right and vice versa. Aileron stick right move right elevon up and left elevon down, and vice versa. Elevator stick down, moves both elevons up and vice versa.
9. The elevons should move +/- 1 inch. The rudder should move +/- 1-1/2”.
10. Ensure prop is moving in correct direction, meaning you should feel the SkyCart move forward. If it doesn’t simply unplug any 2 wires to the motor and swap them.
11. Also, make sure the prop is on in the correct direction, which typically means the numbers printed on the prop should face forward.
12. Optional: Cover lead edge of main wing with packaging tape to help protect it. Spray with spray adhesive first to help it stick better.
Part 7. What Might I Do Differently?
1. Now let’s cover some things I might do differently on my next build.
2. Try smaller battery. 500mah 3 cell.
3. Use lighter control rods on elevons
4. Move the rear axles off the elevons, so you don’t put too much stress on them
5. Place rudder servo further towards front of cart.
6. Put the rudder servo in the middle, with a double sided servo arm, with control rods on both sides, to provide even turning
Useful links:
1. SkyCart plans: http://www.rcgroups.com/forums/showpost.php?p=12953243&postcount=198
2. SkyCart RCGroups thread: http://www.rcgroups.com/forums/showthread.php?t=1094114
3. SkyCart character and wheel graphics can be found in here: http://www.rcgroups.com/forums/thumbgallery.php?t=1094114&do=threadgallery
4. Plans for main wing: http://static.rcgroups.net/forums/attachments/3/3/6/8/5/2/a5463101-98-SkyCart_Main_Wing_not_to_scale.jpg
5. Plans for other pieces: http://static.rcgroups.net/forums/attachments/3/3/6/8/5/2/a5463102-149-SkyCart_ExtraPieces_not_to_scale.jpg
Links to supplies needed.
1. Transmitter and receiver of your choice.
2. hexTronik 24gram Brushless 1300kv Motor: http://www.hobbyking.com/hobbyking/store/__2069__hexTronik_24gram_Brushless_Outrunner_1300kv.html&aff=210817
3. Stick motor mount: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9869&aff=210817
4. 10 Amp ESC: http://www.hobbyking.com/hobbyking/store/__14870__H_KING_10A_Fixed_Wing_Brushless_Speed_Controller.html&aff=210817
5. 8x6 Propeller: http://www.hobbyking.com/hobbyking/store/__7154__TGY_Slow_Fly_Prop_8_6SF_w_shaft_adapters.html&aff=210817
6. Prop saver : http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8237&aff=210817
7. 3-cell LiPo battery, 800mah (could go as low as 300mah and try a 2-cell instead): http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9173&aff=210817
8. Two control rods for elevons (I used 3mm carbon fiber tubes with 2mm threaded rods inserted with CA, but you could use something else)
9. Rudder control rod: used one Hobby Zone Super Cub control rod, cut to 3.5” inches.
10. Three 9 gram HXT 900 servos: http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=662&aff=210817
11. 3.5mm bullet connectors for ESC and motor (3 male, 3 female): http://www.hobbyking.com/hobbyking/store/__68__PolyMax_3_5mm_Gold_Connectors_10_PAIRS_20PC_.html&aff=210817
12. Power connector for ESC to match battery (e.g. JST female connector): http://www.hobbyking.com/hobbyking/store/__9683__Female_JST_battery_pigtail_12cm_length_10pcs_bag_.html&aff=210817
13. For main wing, sides and vertical stabilizer, one 24x36 9mm 1.3# EPP foam sheet: http://www.rcfoam.com/index.php?cPath=82&osCsid=7f5658bfa302d12c84b6545d9a4527fa
Could also get away with Dollartree foam board, but it won’t be as flexible and crash-resistant as EPP.
14. 3mm Carbon fiber tube for front support (15”), rear support (15”) and rear axles(2 x 6”): http://www.rcfoam.com/index.php?cPath=94&osCsid=7f5658bfa302d12c84b6545d9a4527fa
15. Two 6” long 1.5mm diameter piano wire for front axles. Wire needs to fit inside CF tube.
16. Scotch Extreme Tape for hinges: http://www.amazon.com/Scotch%C2%AE-Extreme-8959-RD-Inches-Yards/dp/B001AFKV0S/ref=sr_1_1
17. Also for hinges, Welders glue or Beacon Foam-Tac glue: http://www.rcfoam.com/product_info.php?products_id=1243
18. 3M Spray adhesive to glue character printout onto vertical stabilizer: http://www.rcfoam.com/product_info.php?products_id=1240&osCsid=7f5658bfa302d12c84b6545d9a4527fa (also used for helping hinge tape stick to EPP)
19. Use hot glue for gluing most of the pieces together, except the hinges.
20. For motor brace, two 4” 3mm carbon fiber tubes or bamboo skewers.
21. For making wheels, one 1” foam board from Home Depot, Lowes or Hardware store. You could also use EPP method described in the RCGroups thread.
22. Eight plastic gift cards for making wheel hubs and control horns.
23. For front axle side supports, two 1” x 1-5/8” plastic gift cards or plywood pieces
24. For wheel collars, fuel tubing or hot glue.
25. Velcro to keep ESC, battery and receiver in place.
26. Spray paint, if you want to paint it.
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