Fun Projects for your LEGO MINDSTORMS NXT!

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Snowmobile Race
Building: Intermediate
Program: Easy

Building Instructions












Use one of the longest (50 cm) wires to connect the snowmobile that uses the wide 20 and 12 tooth gears to port C on the NXT, routing the wire through the two wire holders as shown below.

Use the other longest (50 cm) wire to connect the other snowmobile (with the 24 and 8 tooth gears) to port A on the NXT.

Snowmobile Race Programming

Use the Snowmobiles program for the Snowmobile Race.  This program simply runs motors A and C at full power.

Starting the Race

Start the two snowmobiles on opposite sides of the NXT brick with their wires extended, as shown below.  You can adjust the length of wire given for the port C snowmobile by pulling it through the wire holder on the NXT brick.


  • By changing the amount wire given to the slower (port C) vehicle, see if you can make the race even, or make the faster one pass the slower one, or make them crash.

  • Try modifying the design of one of the vehicles, or design your own to see if you can make it faster.  Try different gear combinations, which will result in different gear ratios.  A higher gear ratio (bigger gear driving a smaller gear) will make the wheels try to spin faster, but if you make the gear ratio too high then there won't be enough power to get going, so you will have to experiment to find the fastest combination.  How fast you can go will also depend a lot on how fresh your batteries are.

    You can also combine more than one set of gears to multiply the speed a second time.  The picture below shows one way to do this.  If you do this then you will need to reverse the motor direction in the program for that vehicle.

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