Introduction: Building a Solar Powered R/C Car
This is my newly completed Solar RC Car. I built this car to spark interest in competing in a Solar Race in Summer 2009 in the U.S. This project used many off the shelf hobby parts and could be built by a R/C hobbyist with experience in kit building and soldering.
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This car was designed to take an Associated Style Pan Car and expand the size to accomendate a solar panel. I did this for a few reasons. Cheaper than buying new parts. Critical parts already engineered to tight tolerances. Finally, very easy to adapt for my application. My donor car was an Associated RC10L3 oval car.
The first step is planning and gathering materials for the car. Nearly everything I used in this car was bought from a local hobby shop or source off E-bay.
Associated RC10L or RC12L style car for donor parts
Motor: Just make sure you can mount it into the Motor pod and use the right pinions.
FOAM or other material for Chassis
1/8" Birch plywood for model airplanes
1/16" Piano wire and Wheel Collars
Your choice of Radio System with Servo
FOAM SAFE GLUE Polyurethane Glue ( Elemers or Gorilla )
Wire. (6 ft each of Solid and stranded of wire near 18ga size)
Motor Controller: You need at least a 8Amp rated controller.
And various nuts/bolts/screws and hobby parts. Your needs will vary.
Total cost would be around $400 if going all out like I did. I bought fairly high end motor and controller, solar cells and radio gear.
Planning the Car, I drew everything out onto poster board to make sure it all fit and worked in the space I wanted.
More Videos in later steps
Solar R/C Sites
Step 1: Building the Chassis
I designed my car so that the chassis is the solar panel. Everything is attached to the panel to make it function as a car.
My foam sheets were too small I had glue together two sheets to make a larger sheet. I used the glued seam up the middle for reference to keeping cutouts aligned. A simple line drawn up the middle of the sheet could also be used for reference.
The car needs 4 critical cutouts in the foam. The first two cutouts are for the wheel wells. I made 3"x3" to accommodate a 2.4" wheels from the RC10L donor. It is very important two have these cutouts squared and spaced equally on the foam The second cutout is the Servo cutout. This size will vary with the servo and may need to be slightly offset to center the servo horn in the middle of car. The final cutout is for hollow for the T-Plate. The hollow needs to be long enough for the t-plate and shock mount.
If you want to route the servo wire through the inside of the car, now is the time to create a tunnel or slot for the wire. Get a long enough extension to reach from the RX to inside the servo cavity.
Now to make plywood pieces for mounting the RC10L parts on. You will need two pieces for the front A-arm suspension mounts. One larger piece for mounting the T-Plate and shock, and finally once more piece to mount the servo onto. Make the gluing surface large so that the plywood is not ripped from the foam under stress. To make sure the mounting holes for the RC10L parts were correct, I double sticked taped the plywood pieces to the graphite chassis. Using a pencil transfered the mounting holes into the plywood.
Test fit all the RC10L parts and servo to the plywood pieces then test fit the pieces into the cutout cavities. I drew reference lines on the plywood that were squared or in-line to the mounting holes. I used these reference lines and a square to keep all items true to the center line of the car.
If the pieces fit and can be lined up with the center reference line then you can proceed to glue them in place. Remove the RC10L parts, apply glue and position correctly. I used a carpenters Square to align the center line and the suspension mounts. Apply some weight to keep the polyurethane glue from expanding and shifting the location of the piece. It may be better to only glue one piece at a time as glue sets slowly. This step could be done over a few hours or days to ensure everything remains true in placement.
Step 2: Building the Power Pod
This step will need the Associated RC10L style motor pod.
First Step is to put the appropriate spur gear on the axle/wheel assembly. Then attached the motor to the mounting bulkhead with the provided cross brace that came with the motor. Attach the Pinion to the motor shaft and align the gear and set the proper gear mesh.
Once the motor is in place, move on to preparing the motor controller. The power input wires will need to have a male connector to plug into the solar panel. If installing a capacitor, the male power connector would be a good place to solder the capacitor leads. The motor leads will need to have the same style of connector as found on the motor. Most motors come supplied with connectors. Now attach the motor controller the Motor Pod and connect to motor leads. I used zip ties to attach the controller. Now it is time to place the Radio Receiver or RX. I used servo mounting tape for this task. Test the function of the motor pod with a battery similar in voltage to the solar panel.
Step 3: Building the Front Wheel Assemblies
Build the front A-Arms to the directions that Associated provides. In most cases if using a donor RC10L the assembly is already built as it was for me.
Now comes the tricky part connecting the wheel assemblies to the steering servo. Many ways to accomplish this, and imagination will help. My final design used piano wire and Du Bro EZ servo connects and wheel collars.
I then took a piece of piano wire that I sharpened and poked a tunnel through the foam from the steering wheel to the servo horn. I expanded the hole a little more with a dowel rod. This tunnel is for the Linkage. I measured the distance from the servo center to connecting point on the wheel and then added a few extra inches. I bent a 1/2" 'L' at the end of the wire. I inserted the wire into the tunnel with the 'L' being at the servo. The 'L' is connected to the servo horn and held in place with a wheel collar.
Center the servo horn! Point the Wheels straight.
Using a marker, I marked off the excess piano wire that needed to be trimmed off but also left a 1/2" extra for error. Remove the linkage, trim, then reinstall.
Step 4: Pre-Finalization Testing and Assembly
This is by far the most critical step and do not skip.
Attach the RC10L parts to the chassis:
Attach the T-plate and Shock and Mount to the Chassis mount. Make sure the Tweak Screws are set to prevent the plate from rocking.
Attach the POWER POD to the T-plate using only the Outer screw holes, not the center hole. Attach the Shock to the upper POD and Plug in the servo extension to the RX.
Insert the Wheel Assemblies. Connect the steering linkages to the servo and steering block. Align the wheels with the servo horn being centered.
Time for TEST DRIVING.
Connect a battery similar voltage and power rating as the solar panel. Test the car in many driving situations. Full speed, slow starts, hard starts, sweeping corners, chicanes, and full switch back corners. Make sure wheel alignment is good and tire ware is minimal.
Don't just be content with the car, make sure it is 100% perfect in handling. Fixing problems will only get harder later.
If the car is a pleasure to drive then foam at this point could be coated or painted. Make sure the covering is FOAM SAFE
Step 5: Finialization and Solar Panel Assembly.
Once the car is drivable and covered you can now assemble the panel. Solar cells can be very very fragile which is why this is the last step.
Using card stock make mock solar cells and place them on the car to ensure the arrangement still fits from the first playout on the poster board.
Assemble the cells into strings to fit the layout of the mock layout. This step will most likely require soldering, and will need decent soldering skills. Once a string is assembled, check the Voltage of the string to ensure good connections. Using a mild glue like rubber cement, attach the solar strings to the car. Connect each string to the next solar string by using jumper wires. My jumper wires between strings was solid 18ga magnetic wire. Insulated wire would have worked too. Attach a female plug to the stranded wires used to complete the final connection from the panel to the POWER POD. Then solder the stranded wires to the panel's positive and negative . Once again check the voltage to ensure good connections.
At this point you should be have completed your car. Congratulations!!!!
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