View Full Version : A challenge for all you hobbyists.

04-07-2006, 05:22 PM
alright, i've got a school project and i'm interested in getting some ideas from the creative people here. here's what i've got:

-a balsa wood car that we have to use (about 7-8" long by about 2-3" wide)
it is empty and has about a 1.75-2" x 5-6" space inside. the space is about 1-2 inches tall.

what we have to do is design a way to have the car roll down a 45deg incilne into a wall. the catch is the car must hold two normal sized eggs and they must not break after the crash. we are not allowed to use anything that will slow the car down in it's travel down the ramp. the options are pretty simple: use a lot of padding, use a spring, whatever. easy.

but i want to do something that is really cool and outlandish, but will still work successfully.

also, the eggs must be able to be easily extracted after the crash. and keep in mind that the heavier the car is, the faster it will roll.

if needed i can get more details on the length of the ramp and exact car measurements.

gimme the best ya got!!


04-07-2006, 06:56 PM
I'd wrap the eggs in saran wrap, support them in the car and then fill the area with spray foam. When this hardens cut the foam around each egg to remove it in such a way that it can be replaced to securely hold the eggs. This will be light and since there will be no localized shocks anywhere on the shell of the egg (the whole surface is in contact with the foam), it shouldn't break.

Good luck with it!
Jarod Matwy
Winnipeg, Canada.

04-07-2006, 07:03 PM
wow, i love that idea!

i'll look into it today at work. (i work at a local ace hardware store)

04-07-2006, 07:15 PM
For something "cushier" than the spray foam (Great Stuff?), I would look into a dense car washing foam sponge. Trim to fit so its fairly tight inside the car. Then slice a slot into the top and hollow out a little cavity for each egg but making sure they are still snug. Its light, and should be pretty shock absorbing.

Thats not really cool or outlandish though...

Are you allowed to tinker with the eggs or exterior of the car? If I could I would hollow out the eggs (pin hole on each end and blow hard). Hard boiling is an option, but the hollow egg will be lighter and still strong.

Andy m
04-07-2006, 09:39 PM
As the car will be hitting the wall at a 45 degree angle the eggs will have to be protected on top as well because the sudden stop will tend to make the rear of the vehicle pich up causing the whole length of it to hit the wall.
I have no idea what size a "standard" sized egg is in the US but if it is around the same as here in the UK the eggs will have to sit one behind the other if the maximum width of the loadspace is 2".
My feeling is that a box made to fit the space in the car with 2 compartments lined with memory foam (the type used in motorcyclists jackets/trousers) would do the trick. Obviously a lid lined with the same stuff would have to be fitted as well.
The eggs should be placed in the container lying on their sides, that is, the pointy bits facing the front as that is where all the strength lies in an egg (have you ever tried to crush an egg upright between your thumb and forefinger?) ;)

04-08-2006, 04:56 AM
no, we can't tamper with the eggs. they will be standard (probably the same as in britain) eggs uncooked etc.

as far as i've heard (i need to verify this before i build this thing) the down slope will be hitting a wall that is also 45deg to the ground so that it will be a collision at 90deg to the decline.

i def think the sponge and foam ideas will work, and i could do that for an insurance policy, but i'd like to hear some ideas that are wacky.

i think the competition includes a category for most innovative idea. the projects is based on car safety but i think any crazy idea would be great.

i can get some pics of what i have to work with in terms of the car and eggs, if that would help.

and fyi, this has nothing to do with the grade or winning, it's just because this interests me and i'd like to do something that would awe people as well as myself.

tim hooper
04-08-2006, 08:34 AM
OK, now that you've got us doing your homework for you........

How about a cradle, suspended by rubber bands, to carry your eggs?

I'm no expert, but it would seem to me that the more room you can give your eggs to decelerate on impact, the greater your chances of success.


04-08-2006, 04:01 PM


Nitro Blast
04-08-2006, 04:33 PM
ok heres a wierd one... go for the ooze mess....

get yourself some of that goop... you can use lots of materials... he kids toy "slime"... Jello..... or some of that goop that goes in those thermal ice packs... Filling the void with something like Marshmellows, or even Penut Butter will get a good reaction from the viewers. Just as much as the task, folks will remember the show. PRESENTATION and DRAMA are king. Act it up funny boy and you will be the hit of the show.

Create a pocket to hold the goop, slip the egg in... presto. A real slimy mess to remove (maybe even eat the jello as you remove the egg for some real 'ugs' from the crowd)

As I typed this I even thought of more eggs.... use the goop from a few eggs (crack them open into the volume) and insert the whole egg. Suspended in the egg-fluid they would be ok.

I have done a few of these challenges, and found the more messy, wierd, odd and funky the better.

I did one where we had to save the egg from a fall. All I did was go buy a box of rubber bands. A big box of trusty #64's and all I did was put the egg in the box, and throw it over the rail. I though for sure it would break, but it didnt and the award for the most simple soloution went to me.

If you can apply anything to the car, put a mondo pice of foam as a bumper, that will help tons.

Good luck, and please share your solution and results!

04-10-2006, 02:54 AM
i like the ideas, guys. all of them would probably work, and some are really interesting.

keep in mind that i'm not doing this for anyone but myself (and now for all you guys haha) and i could get an easy A if i needed to with 10 mins of effort.

with that in mind, lets try to think more complicated. i can think of the simple solutions such as immersing the eggs (THERE ARE TWO) in a foam, gelatin. (btw, i tested the eggs in the car earlier and i have about an inch of extra length when the eggs are laying lengthwise, TOUCHING. but i can mod the car if need be.

how bout a moustrap that would fling the eggs into the wall on impact? haha that would be great, but i think the teachers would have a cow at my mockery. especially since the eggs represent humans.

or what if i used the eggs as the wheels on the rear axle?

but i'd like to hear some ideas of more like a contraption. this is an engineering project. i'll brainstorm some and come back with some ideas.

think outside the box.

04-10-2006, 03:07 AM
Actually if you get the low expansion/water cleanup spray foam it never really sets up like the regular stuff so it'd probably make a real good shock absorber.

I'd basically cover the eggs then cut the set up foam in half to make for easy eggstraction.:D

:edit: if you want complicated what about a baloon connected to a CO2 cartredge. Devise a way of piercing the canister on impact which fills the baloon like an airbag which will probably have enough force to fling the eggs back up the ramp into the launcher's face. :D

04-12-2006, 02:08 AM
i got a pretty good setup going now using carved out sponges. so that's my insurance policy so i have a backup plan if all else fails.

hmmmm well i wish the project wasn't so constricting. i like the drop an egg from a building much better.

orrr here's what i was thinking: airplane ejection seats!

you tie a string to a mousetrap which is on a foam glider plane. then you throw the glider and when the string pulls the mousetrap springs and sends the egg flying out. then the students have to devise a scheme for getting the egg to the ground safely. (maybe with limited materials).

hey at least it would be more fun...