Introduction: Mars Rover Curiosity or Perseverence Wind Powered DC Motor Driven
Make your very own wind-powered DC battery motor driven replica of the real Mars Rover Curiosity or Perseverence (launch July 2020). Both are similar but Perseverence will have some added features. If made and tested correctly, your rover will move at a steady pace (not made for speed) and also in a straight, linear path. Too light and your rover will go crazy in circles. Too heavy and your rover will not move at all. Have fun learning about DC electricity, series/parallel circuits, wind energy, and the surface of Mars!
Chassis: Foam core, cardboard, light-weight aluminum, clear plexiglass or acryllic
Wheels and axle: Cheap store-bought car/truck. Make sure your axles are long enough for the width of your rover chassis and doesn't impede the wheels from spinning. Or hobby/electronics store you can purchase both wheels and axles. 4 wheels/2 axles should do the trick
Model motor: 3-6v should be OK. Any science kit or hobby/electronics store. Amazon?
9V battery: Dollar store is OK but you will go through quite a few if you test it often
Battery connector: Hobby/electronics store. This will also serve as your switch so it is important. Has red/black wire leads coming from it. You may want some extra wire to reach your motor position
Model propeller: Hobby/electronic store. You will need help to drill the exact whole where the motor shaft goes into the propeller. Should make a nice snug fit. Can even glue it to make more secure. 5/32" drill bit I believe
Step 1: Parts Is Parts
Where can you get most parts?
Home (be creative)
or I recommend:
Note: 9V battery connector is NOT $18.95 but is not listed in the store database. They are usually packaged loose and they are very inexpensive and also very crucial
Good assortment of propellers. Remember your motor shaft needs to fit snugly into the propeller hole and may need to be drilled. Get help with this. You can glue it but it needs to be a snug fit.
Step 2: Determine Your Chassis Material and Design
Your chassis is the body of your rover. It needs to be strong enough to support battery, motor/mount, and axle holders for underneath plus wheels.
Tinker some designs. Rectangular 10-15cm wide, 20-30 cm length is tried and true although I have seen triangular, octagonal, and other shapes work. Make PRECISE cuts. Sometimes a mm or 2 will make the difference between a successful rover and not
I personally like to use foam core which you can get at any dollar store. Don't bend it. Get help cutting with either an exacto knife or hacksaw blade.
Other materials that would work for chassis:
"Measure twice, cut once" Very wise saying that holds true
Look at some of the student designs. Your chassis can be flat 2-D, box prism, pyramid shaped 3-D, your choice! Be creative
Common beginner mistake: Wanting to use swivel wheels to go in multiple directions. Wind power wants to drive it straight
Use sandpaper to smooth out the edges and sides if you want
Step 3: Measure Your Axles and Attach Your Wheels
Axles can be almost anything. Wire coat hangers, existing axles from a toy, aluminum rods, wood BBQ skewers
The most important thing with these is they roll smoothly on a flat surface like a table
Your axles should not be too wide or too close to the chassis of your rover
One option is to attach the wheels to the axles so they all roll together
Another option is to glue the axles to the bottom of the chassis and have the wheels spin with as little friction as possible. You might need rubber stoppers on both sides of the wheels so they don't fall off
A good rule of thumb is to align the axles about 1/4 of the way from each front and back side. 1/2 would be towards the centre and weight would be distributed evenly
Measure so your axles are PERFECTLY LEVEL. You might need some help with this so your rover travels as straight as possible
Plastic straws make pretty good axle holders yet there often is some wiggle room. That's only if you want your wheels to spin with your axle
Step 4: Add Your Motor Mount and Battery Holder
NOTE: You can use glue gun or regular white glue (no glue stick) White glue needs to dry overnight and glue gun you can use almost immediately. Once you glue, it's permanent so be careful
Pro tip: Use straight pins to hold pieces in place and take out once glue is dry or leave in!
Motor mount: Must be VERY secure (no wobble) and towards the REAR of your rover. If you LEAD with your motor and prop, it will get damaged if it runs into a wall. Make sure it is high enough so the prop doesn't touch the ground OR the edge of your chassis. Attach the prop at any time and TEST with battery so air flow goes AWAY from the motor. Designs will vary, be creative. There are many correct motor mount designs
Pro tip: Once you get airflow direction, mark the RED and BLACK leads on the motor so you can connect easily
Pro tip: You can test the motor just by touching the positive and negative leads right from the battery. WATCH YOUR FINGERS!
Battery Holder: This is important as you don't want your battery sliding off during test runs. You want it accessible because you need access to change it AND for your switch. IF you don't have extension wires, you want to put the battery holder within distance of your motor. Your battery can be vertical or horizontal. The switch will work both ways
Pro tip: If both your motor AND battery are TOO CLOSE to each other, your weight distribution will be uneven. Make sure to centre both of these things so it doesn't tip or lean to one side
Step 5: Trial and Error After Each Step
Always test after each step. Then THINK about what is going right and maybe backtrack to make some minor adjustments.
Certain things you can fix. Other mistakes you might need to start that step over again.
Take your time, be patient, try to have an undisturbed workspace. Don't make cuts or use messy glue on your good table. Always cover your work space and get help with parts like cutting or drilling.
Wait until the very end to decorate using various materials: Tin foil, markers, tape, paint
Watch the videos provided as I will take you through the process
Use two people when you test so they can "catch" the rover and turn off the switch. Outdoor testing is fines as long as it's not too windy
Speed is not much of a consideration unless you want to know km/hr
SPEED CHALLENGE Estimated km/hr _____________km/hr
10 m in 10 seconds = 10 divided by # of seconds for 10 m X 3.6 = km/hr ________ km/hr
example: Rover A took 4.5 seconds to travel 10m (assuming it stayed within 2m wide track
10/4.5=2.22 X 3.6 = 8 km/hr
DISTANCE CHALLENGE Estimated distance to stay on a 2m wide track ____________m
Measured distance to the nearest .01 ________________m
example: If Rover A travels more than 10m you would simply say 10+ or 3.5m, whatever it traveled straight
Linear distance is what we are after. We usually make a track (chalk if outdoors?) 2m wide X 10m length and make hashmarks every 1m
Be careful if your driveway has a slope. Will go faster on the way down and slower on the way up. Test each way to determine the difference but try for a level surface
Step 6: Be Proud, Record Your Work, and Ask Questions
This is a great partner project. Unfortunately, you will have to use a family member during quarantine
I'll try to itemize and price some supplies from a couple different places. You'll be surprised how many household items you could use
You can name your Rover. Does not have to be Curiosity or Perseverence. You could take design functions from these rovers and include them if you want. Obviously the real rovers do not move by propeller. Be creative, have fun, and I hope you win the contest!
Step 7: Solar Challenge (Junior Solar Sprint)
They have competitions throughout N. America for JSS
Obviously you need the sun. It's a fun challenge but I find our battery/propeller to work more consistently