# Pullback Mechanism vehicle

1. Mar 1, 2009

### Gary1990

Hey all,

Our team is currently working on a project wich contains the pullback mechanism like the ones you find in toys. We are competing against other teams and have a fun match at the end.
The idea is to pull or push the vehicle back 1 meter and store as much as possible energy.
We only have 30 seconds after the push/pullback to adjust the vehicle but it is not allowed to store extra energy other than the energy you stored from the 1 meter push/pullback. After releasing the energy (when the vehicle starts riding) its also not possible for the rider to add extra energy (e.g. moving back and forth to steal extra lenght)
The goal is to store as much energy as possible to get a great deal of traveling distance.
We have several idea's about the construction and the energy storage (we are planning to use springs of a special composite)
We have calculated that if we are to push the vehicle back with a force of 800N, we can only reach the maximum speed of 4 meters per second with the energy we put in to.
A few members are currently working on the wheels because we need to watch out for slipping while pushing/pulling back or while riding.
We have a low budget of 150 euro's.. we are trying to find some sponsors to realise our project.

Greetings,

Gary

2. Mar 1, 2009

### NateTG

Are you going for speed or distance?

3. Mar 2, 2009

### Gary1990

We are going for distance. Speed is irrelevant. We just calculated that our maximum speed would be around 4 m/s.

4. Mar 2, 2009

### xxChrisxx

What kind of energy storage are you thinking of?

For the best distance you want the energy to be released incrementally and at a steady pace. As soon as I saw this I thought of Da Vinchis self propelled cart.

5. Mar 2, 2009

### NateTG

How big is the vehicle going to be?
Does it have to turn?

Depending on scale, I think I'd be looking for a system with a spindle and a dropping weight.

6. Mar 2, 2009

### minger

That's exactly what first came to my mind. Essentially you have your wheels connected via belt/chain to a mass. As you push the car back, it raises the mass. When letting go the potential energy of the mass is converted to rotational acceleration of the wheels.

The only limiting factor is structurally supporting the mass, stability, etc. However, that's trading off for potentially storing as much energy as needed (to beat the others).

7. Mar 2, 2009

### xxChrisxx

Wouldnt a steady release of energy get them further than a single impulse from a dropping weight?

8. Mar 3, 2009

### minger

Well, you wouldn't get an impulse from dropping a weight if its geared correctly. Basically, you have the shafts and wheels tuned such that the force from the mass is 'just' enough to accelerate the wheels.

Let the mass drop slowly generating a lot of rotational energy.