The main thing to remember when you are planning is that you will be supplied with a limited amount of parts. So think basic! The person who tries to be fancy always looses. Many times I've seen cars that don't even have steering come in the top three. The people that win almost always have these five things:
Low center of gravity
Low to the ground
Weight over the wheels
I'll show you how I achieved these things in a battle bot I made that won first place, and I'll give you some tips along the way.
I hope this guide will help future battle bot builders!
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Step 1: Creative Planning
Your planning time can be some of the most valuable time you have, and depending on the contest you might have very little. You do not want to waste it!
Think simple! You will be given a variety of parts and you probably wont want most of them. I know that a lot of times they give you a bad selection of parts to make you think and be creative, but never forget the fundamentals! Don't waste time and parts on fancy spinning things and lifts to flip the opposing car. I made this mistake my first time to compete and I had to spend half of the time I got to battle rebuilding my car. Just don't do it!
Step 2: Low to the Ground
I know that some of you are thinking that if you use the small wheels you will have less friction between the wheels and the ground. That is true, but there are ways to overcome that. If you only have the big wheels be sure to build the front of the car as close to the ground as you can.
Step 3: Weight Over the Wheels
Here is a helpful tip. Always use all of the parts you are given! Start by making the basic battle bot then add all of the extra parts over the wheels. Don't build it too high though. You want to keep a low center of gravity. If you build it too high it will be easy to flip your battle bot.
There is almost always those one or two people that have the majority of their parts left. They always loose. You want your bot to be the biggest and most compact one there.
Step 4: Steering
They almost always give you two knex motors for this reason. The way you create steering is by having two different axles that can move independently. Each axle has one motor on it so when you turn both on it either moves forward or backwards and depending of what combination of on and off you use it can steer in any direction.
Step 5: Keep It Flat
You also want to have a wide wheel base. Make it at wide as you can. This will make your car more stable, and will be less likely to get knocked over. You might want to add a stabilizing arm on the back like I did. If you let it drag behind you it will cause a little more friction.
If they give you gears be sure to gear down the wheels, but chances are the wont. I have never been in a competition where they have given you gears.
Step 6: End
If you ever need help on your battle bot or any other knex project please let me know and I'll be glad to help!