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Fastest Mousetrap Racer

rhali8
  • 45 months ago

Hello Everyone!

I have an engineering assignment, and we have to build a mousetrap racer using a specific mousetrap. It is on a 2m drag strip, and our goal is to get it across the line as fast as possible. Bonus points if we somehow get it to leave tire marks on the starting line. (That isn't happening :D)

We have to consider:

  • Materials of wheels (friction)
  • Mass of chassis material (Lightweight = better)
  • What kind of drive the car is (4WD, Front, Rear)
  • Axle friction (We don't want the car to slow down too quickly once it stops accelerating)
  • Lever arm length (From the mousetrap)
  • Size of wheels
  • Surface area of wheels to ground

I'd like the design to look nice and be super lightweight and fast. I've got in mind:

  • A 4WD system that pushes all power to all four wheels on takeoff
  • 1:10 on road slick tires (I believe they are the fastest, but I don't want to lose power to wheelspin)
  • A super lightweight material such as balsa wood for the body, probably going to be carved so it is super thin and looks like this
  • Axle friction that is almost nonexistent, will probably oil the axle before the start

That's what I'm thinking. I'd like some advice and tips on how to build it and any idea is welcome. I'm also having trouble figuring out how to make a 4WD drive train work. Anyways, thanks guys!

Comments

  • 45 months ago
  • 3 points

I'd highly recommend visiting drag race sites and read how people build their cars. 4wd isn't always the way to go (look at the new corvette. Better 0-60 than any of the 4wd sports cars and some hyper cars and it is rear wheel drive). You add unnecessary weight, parts, and complications. 4wd is great for vehicles in road tracks, but not in drag racing.

Use as few parts for the drive train as possible. If you use a lever system use a very short lever. Get the power to the wheels as quickly as possible and the distance from the "motor" to wheels as short as possible. A front wheel car would probably be the best bet here. In small cars pulling is far more efficient than pushing (specially since weight distribution isn't a concern in such a small model) and since you don't need to worry about steering it's a fairly easy system (why most modern cars are front wheel drive, very efficient). I'd use graphite on the axles instead of oil (oil provides a lot of friction at the get go).

Cool little link of ideas

These are just my thoughts.

  • 45 months ago
  • 1 point

I'd highly recommend visiting drag race sites and read how people build their cars. 4wd isn't always the way to go (look at the new corvette. Better 0-60 than any of the 4wd sports cars and some hyper cars and it is rear wheel drive). You add unnecessary weight, parts, and complications. 4wd is great for vehicles in road tracks, but not in drag racing.

That sound great, but from what I understand a certain amount of power is going to be delivered to two wheels. If I add another lever arm to the second set of wheels, I won't lose any power will I? I'm pretty sure that same power will be delivered to all four wheels as it would to two, increasing the take off speed since no extra force will be required to get the front wheels moving.

Use as few parts for the drive train as possible. If you use a lever system use a very short lever. Get the power to the wheels as quickly as possible and the distance from the "motor" to wheels as short as possible.

Ok. That sounds good, I'll base my mechanics around that.

I'd use graphite on the axles instead of oil (oil provides a lot of friction at the get go).

That sounds really good too. That link is really helpful as well.

Thanks for the tips! :)

  • 45 months ago
  • 3 points

With two levers you will lose power. The mouse trap only has X amount of power to apply. If you go 4wd you are spreading that power to two points (instead one just focusing all energy to one point), which will reduce launch time, speed, and a number of other factors. That's kind the most basic way of putting it. Power is always distributed, and not always equally.

To improve a system that's 4wd over a 2 wheel drive with the same engine, you would need to increase the power output of that motor to compensate for the additional drive train.

It has been a long time since I was in a physics/engineering class. Hope i'm not f'en up my vocabulary.

  • 45 months ago
  • 1 point

With two levers you will lose power. The mouse trap only has X amount of power to apply. If you go 4wd you are spreading that power to two points (instead one just focusing all energy to one point), which will reduce launch time, speed, and a number of other factors. That's kind the most basic way of putting it. Power is always distributed, and not always equally.

Ah. I see. In that case, front wheel drive it is :D

It has been a long time since I was in a physics/engineering class. Hope i'm not f'en up my vocabulary.

Hehe, no problems.

  • 45 months ago
  • 2 points

Btw what you would actually have is AWD, power distributed equally tonall tires. 4WD is a little different.

great link on the differences

  • 45 months ago
  • 1 point

Ohhhhhhhhhhhhhhhhhh. I always wondered what was different about them. I thought they were the same thing lol. Ty.

  • 45 months ago
  • 2 points

Do not bother with 4wd at all. Waste of energy in that type of scenario. I did this in HS and had the best car. All you need to do is maximize your gear ratios (size of spindle to size of wheels vs length of string and arc of mousetrap. It's all trig and its easy trig at that.

Don't worry about friction at all. Line the wheels with rubber piping, or use big wheels, and you will not have any traction issues.

Mine looked similar to this: https://www.youtube.com/watch?v=oI6dHERoz4s but I used larger diameter plexiglass wheels and did 200+ft.

  • 45 months ago
  • 1 point

All you need to do is maximize your gear ratios (size of spindle to size of wheels vs length of string and arc of mousetrap. It's all trig and its easy trig at that.

Ok. Sounds good.

Don't worry about friction at all. Line the wheels with rubber piping, or use big wheels, and you will not have any traction issues.

:)

Mine looked similar to this: https://www.youtube.com/watch?v=oI6dHERoz4s but I used larger diameter plexiglass wheels and did 200+ft.

Holy cow! That's really good. Just for a bit of extra info, we're going for acceleration, not distance. Then once we've finished testing, we'll do a couple drag races.

  • 45 months ago
  • 2 points

For acceleration, just use smaller wheels lol.

  • 45 months ago
  • 1 point

Just a quick question - what is best material for the base? I'm thinking balsa wood....

  • 45 months ago
  • 2 points

Balsa wood is ok, but remember is has little to no tensile strength. What it has going for it is lightness.

https://emilypaterni.files.wordpress.com/2013/01/jenw.jpg

This is a good design for speed off the line.

  • 45 months ago
  • 1 point

Just wondering, some other guy recommended graphite powder to reduce friction on the axle. People on the internet are recommending speed cream. Which should I use?

  • 45 months ago
  • 1 point

ooooo

I'd like to help a little. A mousetrap car is one that uses the lever of the moue trap for power, correct?

  • 45 months ago
  • 1 point

Yep. When the mousetrap springs it makes an axle rotate at high speeds very quickly. I have to make a car out of it :D

  • 45 months ago
  • 1 point

Sweet!

What is the size you are going for?

  • 45 months ago
  • 1 point

1:10 and smaller. I don't want it to be too big, considering the mouse trap is quite small.

  • 45 months ago
  • 1 point

As someone who has done this exact project back in high school my advice is to ditch all the extravagant designs. Your goal is to make it across the finish line in one piece.

Choose a design that is easy to construct so you can have a greater amount of time to test the vehicle and make changes as needed before race day. Research is crucial...look at past winning designs and take note of common features which you can incorporate into your own.

  • 45 months ago
  • 1 point

Sounds good. I'm pretty confident in my engineering, the looks are just mainly for laughs. I won't be spending much time making designs and I'll try really hard to keep the weight increase to a minimum. Some guy is taping an enormous spoiler to the back of his racer. Good luck to him lol.

Choose a design that is easy to construct so you can have a greater amount of time to test the vehicle and make changes as needed before race day.

We've got over 5 weeks to work on it. Should be plenty of time to do plenty of testing.

Research is crucial...look at past winning designs and take note of common features which you can incorporate into your own.

That is some really good advice. Thanks! :)

  • 45 months ago
  • 1 point

I've always looked at these things from a different angle, so here's my quick take on it...

Why not use the mousetrap to trigger a small rocket engine? (such as this quick search brought up... https://www.amazon.com/Estes-C6-5-Model-Rocket-Engine/dp/B000QV0EEK ) That way, you can increase the amount of power available while still using a mousetrap, and this removes the need to worry about AWD/4WD/Front/Rear wheel power. Though, you may need to extend that 2m drag strip or put in a catch box.

  • 45 months ago
  • 1 point

Hehe a C engine would be waaaaaaaay to powerful for a 2m run like this. Little A engines would be best (but still way to much for 2m). If one were to go with a propulsion engine, a CO2 cartridge would be much better and much safer.

  • 45 months ago
  • 1 point

Yea, but more power in shorter time = faster time to complete.

Plus, always good to have fireworks. And incinerate the competition. :P

Then again, I did have a Physics teacher that advocated "MORE POWER!" and was actually thrilled when one of my experiments catastrophically exploded. (That poor egg... :P) Of course, follow all safety precautions. And maybe get a lead vest just in case...

[comment deleted]
  • 45 months ago
  • 1 point

Ahhhh no. The only form of thrust can be the mousetrap. Good try though :D

[comment deleted]
  • 45 months ago
  • 1 point

Yep :P

[comment deleted]
  • 45 months ago
  • 1 point

LOL. I was thinking something along the lines of that XD

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