Amazing & Graceful Egg Drop Contraption




About: I'm a mechanical engineer with a passion for making things.

Recently my AP Physics class was assigned the egg drop project. After experimenting with a few designs I found one that works very well and looks good too.

Although some of the restrictions for the classic egg drop project vary, some of the same prinicples found in this design might be applied to your own device.

The winner for our competition was determined based on the highest P-score. Where the P-score is equal to the below equation (h being the maximum height survived, m being the mass in grams and V being the volume in cubic centimeters). I think my device ended up with a score of about 430 (more than four times the second place score).

Step 1: Materials

The materials I used to create my device:
2 toilet paper rolls
1 manila paper folder (any kind of thicker paper would work just as well)
5 yakitori skewers (long thin sticks)
2 straws
ziplock bag
some thread (optional)

hot melt glue gun (not totally necessary but helpful)
x-acto knife (again not necessary but helpful)

Step 2: Assemble the Body

Start by cutting the toilet paper roll length-wise. Then fit the other roll inside of the one you just cut. Tape it back together so that it is now slightly wider and can just fit the other roll inside.

Take the un-modified roll and cut it in half. This is easiest with an x-acto knife but scissors will work too. Make about 1 inch vertical cuts all the way along the perimeter of one of the halves. Leave about 3/4 inches of space between the cuts.

Step 3: Assemble the Rotors

Now find the other half of the roll you cut up. Poke a hole about half a centimeter from the end of roll (I found the x-acto knife worked well here). Make the whole large enough to fit one of the skewers through. Poke another hole directly opposite this so that the stick can pass all the way through the roll. Repeat this process four more times. NOTE: You will have to increase the distance from the edge of the roll for each skewer so that they can all fit.

Step 4: Cut Out and Attach the Blades

Cut out eight 11cm x 5 cm rectangles from the manila folder. You can of course alter the length of these blades. My project required that the device fit within a 30cm x 30cm footprint but if you're allowed to go bigger, the longer the blades are the more drag they will create giving a better chance of survival for the egg.

Once you have all your blades, attach them to the skewers at slight angles. I used electrical tape to attach mine to reduce weight but I'm sure hot glue or other kinds of tape would work just as well. Make sure all the blades are approximately equidistant from the center of the tube (this ensures that it is the most stable as it gracefully spins downward).

Step 5: Putting It All Together

Now all that's left is putting everything together.

Poke another pair of holes in both the bottom of the roll of the rotor assembly and top of the roll that was slightly widened. This attaches the propeller assembly to the base while also allowing you to easily take it off for transporting or checking the egg.

Create two more pairs of larger holes on the bottom of the widened toilet paper roll to fit the two straws through. Ideally they would be perpendicular to eachother but as long as it's able to support the egg it should be fine.

Insert the bottom half of the role (the one with vertical cuts) into the bottom of the widened tube. I didn't need to secure this because mine was a relatively tight fit but if it falls out when you hold it vertically you should use tape to secure it in place.

Step 6: Finishing Touches

It's almost time to test it....
First get a small ziplock bag and cut the top off (about one third down). Wrap your egg in the bag and insert it into the top of the device prior to dropping it. It should be a pretty snug fit. If it's not fitting make sure the bulk of the excess plastic bag is under the egg when you place it in and the egg is sitting vertically in the tube (eggs are much stronger in this orientation).

Also slightly curl out the bottom cuts so that when the device lands it acts as a sort of spring or shock absorber and spreads out.

You can also attach a thread to the top rotor assembly. This makes dropping the device easier. This is very helpful if you're not the one dropping it.

Step 7: Drop Time!

There you have the finished product! You may want to test it without the egg first to make sure it spins as it falls. If it doesn't check that your blades are all in the correct orientation.

If it's working well it should spin gracefully down and land lightly on the springy cardboard cuts.

That's it! Good luck with your egg drop.



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    60 Discussions


    Question 11 months ago on Step 4

    Does this count as a parachute, or is it completely released?


    Question 1 year ago

    Does this fit in an 6x6 inch square box


    9 years ago on Introduction

    I have a few questions.
    *MY limit for size is what would I need to alter
    • Do the rotor blades actually move? Like spin..isn't that the point?
    *I am not allowed to use skewers, so what could be replaced?

    Thanks....perfect for what I was lookin for...
    2 replies

    Reply 9 years ago on Introduction

    The whole device spins not just the rotors. So if you can't use skewers you can just glue or find some way of attaching the rotors at an angle. Maybe you could cut slots in the tube for the blades to fit in. The angle of the blades maybe an important factor. My belief is that you want the blades as close to horizontal as possible while still getting nice rotation. 10 to 15 degrees from horizontal is probably best.

    For the size constraints.. actually my 30cm cube constraint is almost exactly the same as your 12in cube one (30cm = 11.8in). So my dimensions should work perfectly for you.


    Reply 1 year ago

    does it fiit in a 6 by 6 inch box.


    1 year ago

    Would this fit in an 6x6 inch square box.


    10 years ago on Introduction

    I have to wonder, how many eggs are wasted in the numerous egg drop competitions such as this. PEOPLE ARE STARVING OUT THERE AND WE WASTE EXTREMELY NUTRITIOUS EGGS. Shame.

    7 replies

    Reply 1 year ago

    what if u used water balloons


    Reply 4 years ago on Introduction

    It is not a shame whatsoever. There are plenty of eggs out there to break, and people starve, so what. It's all part of natural selection, a very valid theory that you have no place in trying to go against.


    Reply 10 years ago on Introduction

    Eggs are what - about 15 cents each? The goal of this exercise is *not* to break the egg, but I assume a few presumably break as the team refines their design. Let's assume they're really wasteful, and each team member breaks 6-7 eggs, or about $1 in eggs a piece. $1 for a very valuable lessing in practical engineering seems like a great investment to me!

    Sure, you could donate eggs to a homeless shelter, or dehydrate them and include them in food aid to Burma and China. Trust me - people who run homeless shelters and food aid programs know exactly how cost-effective eggs are when it comes to feeding the poor and starving. And they most likely prefer to get that $1 in cash instead, which gives them a lot more flexibility.

    So now your question becomes:

    Is it more important to spend $1 to teach an engineering student a valuable lesson, or to donate that $1 to feed starving people... In the end, a $1 egg experiment is going to be FAR more cost-effective than a similar experiment using and extra $10 in cardboard, elastic, rubber balloons and hot glue instead.

    After all, it's not as if eggs are a limited resource. Eggs are a great renewable resource - that's why they're so cheap in the first place...


    Reply 10 years ago on Introduction

    You miss the point completely. It's not about the money, it's about the wasted food. Even if they donated an egg for every one wasted, it would still be a waste of an edible nutritious egg. You can't tell me there are no other ways to learn about "how not to break an egg".


    Reply 10 years ago on Introduction

    Except that it's not wasted.

    An egg is multi-functional: yes it's food, but it is also a valuable engineering lesson. Eggs are also used to manufacture flu vaccines, for example - would you call that "wasted"? Biology students do all sorts of interesting experiments using fertilized chicken eggs - great for observing embryo development, for example. Why would it be more acceptable for a biology student to "waste an egg" in a valuable learning experience, than an engineering student?

    There are so many other types of waste more deserving of your attention. Go ahead, break an egg or two to learn something useful. Then go dumpster diving for dinner...


    Reply 10 years ago on Introduction

    I agree with uguy first of all the egg is wasted because after you use the egg i dont think anyone will go and eat it. they will just throw it away even if it did not break. i bet you wont eat it either after you used the egg in your experiment.


    Reply 10 years ago on Introduction

    I'm sorry, but I have to pipe up and add my 2 cents and agree with Patrik.

    The point is that even though the egg is not being eaten, it is not being wasted, because it is being used to educate. Instead of becoming "stomach-food," it is literally becoming "brain-food!" :)


    I am doing this project for class and the teacher says the contraption we make is supposed to reach the ground within 5 seconds. We are releasing them from football stadium bleachers about 15-20 feet high. If I make this specific contraption, if made exactly and correctly, can it reach the ground within 5 seconds?


    Reply 5 years ago on Introduction

    My blades were 22 by 9 1/2
    I dropped it down the stairs, 4 -7 meters I will later do an instructable on how to do it.