Has anyone added springs to a rubber band car?

If so, how did you add them? Did you add it to the stationary point? Will this addition help with the distance of the car?

This is the goal:

"1. your car must be powered by no more than 2 rubber bands. may be any size.
2. body of car may be made out of most common household materials. wheels may be previously manufactured, but body can not be.
3. may not launch or catapult car. must be self propelled." 

Comments

[jeff-o]

It would seem to me that you can't use springs as a extra source of power.  I suggest you use two of the biggest, baddest rubber bands you can get your hands on.  Maybe pull some from a slingshot or one of those gimmicky strength training gadgets.

[Koosie]

Wouldn't that violate number 3?  Or are you talking about suspension springs?

Or do I have the cat by the tail?!

[Re-design]

Doesn't understand what launch or catapult means.

[orksecurity]

The car's motive mechanism must ride the car; you can't build an external launcher to "leave the engine behind" and thus reduce weight.

(Homework problem...)

[bluefly1215]

I see where your going but, the vehicle must be self propelled. This would mean the rubber bands need to be on the car. Thanks everyone for your replies.
I don't think I explained this well enough.
"by no more than 2 rubber bands" can mean just rubber bands OR only two not three or four of them. Therefore the problem arises. 
Koosie, Will the car launch with the spring pulled out all the way? No it's not suspension. And I have 10 cats, which tail did you mean?

[orksecurity]

Almost certainly it means "rubber bands", period. Ask whoever's running the contest, but I'd bet dollars to donuts on that.

[RavingMadStudios]

+1
It means only rubber bands AND two or fewer of them, not OR.

[lemonie]

Springs aren't allowed by rules 1 & 3.

L

[bluefly1215]

What I was thinking is similar to the stretch rubber band method. That would mean adding the springs to the stationary end and when you pull the car back to wind the rubber band it will get to a point where the spring would stretch out as well.Giving the rubber band a bit more stretch, or legnth. Thus letting it go,the spring would first compact then the rubber band will release it's energy. It shouldn't catapult the car, I plan on using two rubber bands  side by side for the power. 
Kind of like the pull back cars and let it go. Anyway that is what I was thinking. Which shouldn't violate the rules.

[RavingMadStudios]

Sorry, it'll violate the rules. The spring would be supplying energy in addition to the rubber bands, which is in clear violation of Rule #1. The spring would, in effect, be funtctioning as an additional rubber band, just not made of rubber.
If your intent is to play rules lawyer and argue that the rules state "no more than two rubber bands", but fail to exclude non-rubber power sources, then go for broke and put a lawn mower engine on it.

[orksecurity]

+1. Sorry.

[bluefly1215]

This is the idea of the function of the car and the rubber bands.
www.instructables.com/id/Robot_Racer_Video/