Egg Drop

[Naval Power]

Was wondering if any of you could share designs that worked for an egg drop project. Its a test grade, and we can' t use Styrofoam, foam, marshmallows, cotton balls, bubble wrap, balloons, water, or food. We can't have wings or parachutes either but its being graded by using the equation:

Score = 1/2 Mass X time^2

Basically that means I need a very lightweight device that falls very fast and prevents the egg from breaking. We're dropping this off of a 30' stadium onto concrete and if it breaks we immediately get a 70 (which isn't so terrible, because most peoples average test scores in there is below 70).

This is my rough design I thought up today in class, I don't know if it would work or not, but if anyone can think up something that they know will work, post it here. Oh yea, the design must fit on a 8.5 X 10 sheet of notebook paper, but it can be any height (I have to lug it to school though, smaller is probably better)

The egg goes in the cone btw, and I'm wondering if adding a small weight would help it accelerate and keep its balance without sacrificing low weight. Thoughts?

 

[taper]

You're on the right track. The trick is to slow down the de-acceleration of the egg. You'll want the egg to hit big end down, since that's the strongest side. If the device tips over and the side of the egg hits something, it'll probably break, so avoid that. You could try something with the egg sitting in a flexible cone, so when the device hits, the egg continues falling, although rapidly and gently slowing down. Drinking straws and rubber bands work well.

 

[madviking]

I was thinking a paper tube that would hit the ground and crumple up, that way the paper would absoarb the impact...

 

[Bill3000]

Find the minimum amount of kinetic energy required to shatter an egg before anything else.

 

[ShannonCT]

If your score = 1/2 mt², wouldn't your score be higher if your design was heavier and slower?

Assuming that your score is inversely proportional to the mass and time², I would encase the egg in a cylinder of gelatin or ballistics gel. They're both great absorbers and distributors of force and will minimize the chance of breakage. You can attach your crumple cone to one end of the cylinder for aerodynamics and speed. What points you lose in mass, you'll gain in time.

 

[emzie]

Are you issued your egg there or can you bring it from home? If you can bring it from home, hard boil it first.

 

[onejayhawk]

The best design I ever saw for an egg drop is a foam egg carton with the egg on one end and a 500 gram weight on the other. Since you cant use foam, consider the design. It collapses to absorb the impact. I suspect that wadded paper would do a similar effect.

J

 

[Nylan]

I have done a few of these, but they all violate the rules (air packets, etc.)

Suspension by rubber bands, if given the right tension, works decently enough, but it's not great...that's all I can think of at the moment

 

[Bill3000]

Flood the classroom with pitch! Extremely high viscosity, ergo high t!

 

[Fetus4188]

Freeze it in a block of ice.

 

[Cheezy the Wiz]

Your goal is going to be to create maximum time for the force to act on the egg, so that the force is spread out. A crumple zone is a good idea, but the cone may be a bad one. I would recommend a double thick crumple zone made of paper crumpled into balls, so the egg sits in the middle and never actually hits the ground. When your device hits the ground it WILL roll, it is not going to stay straight up. In fact, it may even spin in flight, this is why I recommend something even all the way round.

 

[Naval Power]

If your score = 1/2 mt², wouldn't your score be higher if your design was heavier and slower?

Assuming that your score is inversely proportional to the mass and time², I would encase the egg in a cylinder of gelatin or ballistics gel. They're both great absorbers and distributors of force and will minimize the chance of breakage. You can attach your crumple cone to one end of the cylinder for aerodynamics and speed. What points you lose in mass, you'll gain in time.

Lowest score wins a 100, by adding mass you would get a faster acceleration, but the mass would make your score higher as well. Another requirement I may have forgotten to mention was that it has to be easily set up like in class. Ballistics gel doesn't seem like it would work.

Suspension by rubber bands, if given the right tension, works decently enough, but it's not great...that's all I can think of at the moment

I was thinking suspension from something with enough tension to stop it from hitting the sides of the container would work, and wadded paper does sound like a good idea. A plastic bag filled with them, with the egg in the interior?

Freeze it in a block of ice.

That violates the no water rule.

No hard boiling I'm afraid, we are issued an egg in class. I don't know how much of a difference it would make anyway.

 

[Lotus49]

[Man that always uses proverbial commons sense, and finds the line of least resistance]

Since it's available, I would just use modern technology. I.e., a crash helmet. Doesn't break the rules... they're made of plastics, and reinforced with kevlar or carbon fiber. The only challenge would be to strap it down in such a way that it received maximum benefit from the design, as intended.

[/Man that always uses proverbial commons sense, and finds the line of least resistance]

Don't like that idea? Then just use plastic. Some kind of hollowed polyhedron construction, made with flexible plastic strips, while internally the egg is suspended from the external joints via rubberbands from all sides. The only engineering challenge would be to develop the proper rigidity for the plasic struts, in relation to the elasticity of the rubber bands, so that the egg doesn't contact the ground, and the plastic & rubber components absorb maximum impact. A rather large polyhedron, would enable a considerable about of travel, thus the larger you go, the less and less the G-force upon the egg, as it stops.


Alternatively, I could come up with even more complex designs, for example one which would transfer the impact into a device that would induce a centrifugal force onto the egg, spinning it on a lever (which it is securely strapped to) that would actually cause no force-impact at all. But, this would have to be a larger object, and more serious mechanical design. Though, no big deal, if you're serious.

Basically, a truly smart design would take the impact, and transfer it's energy effect upon the egg in such a way as to prevent direct point pressure which would break the shell (since that's the objective, obviously).

But I'm no mathematician. You might want to go talk to those guys.

 

[MOTH]

by adding mass you would get a faster acceleration,

Mostly wrong. In a vacuum something weighing 1 gram or 1 giga gram would fall and accelerate at the same rate. Depending on your design, air resistence might have some very slight affect on a 30 foot drop. As long as you don't make a sail or parachute I would ignore the wind resistence as it won't add much time.

My suggesting is to go with something light with an outer shell. I would suggest 3 8" x 11" sheets of paper taped togather on the long sides to make a tube. Inside the tube use loosly crumpled soft paper (toilet paper?) and use tape over the ends of the tube to keep it in. Outside the tube use loosely crumpled harder paper (printer paper?) taped or stapled all around the outside.

Crumple zone on the outside and cusion crumple zone on the inside.

You will need to test how it falls. If it tends to tumble then you might consider adding a "tail" if it is legal. A kite style tail could add just enough air resistence to resist a tumble. The point isn't to slow it down, but to control its roll.

 

[PrinceOfLeigh]

Hard Boil it.

 

[Masquerouge]

Hard Boil it.

Actually a better way would be to pierce two very very small holes using a needle at both ends of the egg, and emptying it by blowing through one hole.

I suggest this page: http://www6.shizuokanet.ne.jp/kishimh/EGGworld/SAQ/saq_e3.htm

Then when the egg is empty the shell will be so light it will very likely withstand any sort of impact.

 

[Sophie 378]

Something to distribute the force evenly over the whole shell? IIRC, eggs are pretty weak against sharp things but very strong for their size against blunt things. I also recall hearing someone tell someone else about a TV programme where they dropped eggs out of a high-flying helicopter, and they bounced instead of breaking.

Could you make a parachute that deploys after a set time or at a set height, for fast initial dropping and then a slowed descent?

 

[ShannonCT]

Mostly wrong. In a vacuum something weighing 1 gram or 1 giga gram would fall and accelerate at the same rate. Depending on your design, air resistence might have some very slight affect on a 30 foot drop. As long as you don't make a sail or parachute I would ignore the wind resistence as it won't add much time.

My suggesting is to go with something light with an outer shell. I would suggest 3 8" x 11" sheets of paper taped togather on the long sides to make a tube. Inside the tube use loosly crumpled soft paper (toilet paper?) and use tape over the ends of the tube to keep it in. Outside the tube use loosely crumpled harder paper (printer paper?) taped or stapled all around the outside.

What's really important in factoring in air resistance is the mass:exposed-surface-area ratio. The higher the ratio, the lower the air resistance. I tried dropping a stone and a wadded piece of paper in my home. In an 8 foot drop, the piece of paper was approximately 2 feet above the ground when the stone hit, which meant that t² was around 33% greater for the paper than the stone. A wadded-paper-type egg drop device would need to be have 75% or less of the mass of a stone-like egg drop device to be superior.

For a given amount of mass, the more compact the device, the faster it will fall. If you have a design that you are sure will protect the egg, more compact and faster = a better score.

 

[ShannonCT]

Something to distribute the force evenly over the whole shell? IIRC, eggs are pretty weak against sharp things but very strong for their size against blunt things. I also recall hearing someone tell someone else about a TV programme where they dropped eggs out of a high-flying helicopter, and they bounced instead of breaking.

This is why I like gelatin. I've used this before and I'm sure it works. (It's just a matter of having enough surrounding the egg.) Encasing the egg in gelatin gives you a very even distribution of force without the bulkiness of something like cotton balls.

 

[dutchfire]

Are tissues allowed?
I tried once, and I believe it worked quite well. You should at least consider wrapping the egg up in something like tissues insid the construction you're thinking of making.