Introduction: Amazing & Graceful Egg Drop Contraption

Picture of Amazing & Graceful Egg Drop Contraption

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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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!

Picture of 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.


thiakos_889331 (author)2015-06-03

it worked

ThePuzzledBoy (author)2015-05-22

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?

jeremy.richards.73744 (author)2015-04-20

You could do this, or bake a cake. When you are a child, the choice is really hard.

uguy (author)2008-05-25

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.

AlecM4 (author)uguy2015-03-11

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.

Patrik (author)uguy2008-05-25

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...

uguy (author)Patrik2008-05-28

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".

Patrik (author)uguy2008-05-28

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...

instructiondude (author)Patrik2009-01-24

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.

ElChick (author)instructiondude2009-03-06

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!" :)

mcgenius2000 (author)2014-02-12

If anyone knows the time this contraption stays in air, could you please tell me?


TunaTech (author)mcgenius20002014-02-24

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.

BunnyLab (author)TunaTech2014-11-17

How many grams did yours weigh?

TunaTech (author)BunnyLab2014-11-17

Im not positive BunnyLab ,but I believe it weighted about 100-400 grams.

BunnyLab (author)TunaTech2014-11-19

My limit it's 200 grams

TunaTech (author)mcgenius20002014-02-22

its about 10-15 seconds

mcgenius2000 (author)TunaTech2014-02-23

Woah, that's a way better time than me! How high did you drop the contraption from and what were the measurements of your wings?


aramey1 (author)2014-02-05

For step 4, I didn't use 11 x 5 cm squared. I used 5 x 2 INCHES squared. I'm just sharing an example of how the blades can be different on the contraption.

aramey1 (author)2014-02-05

I found a way to use the hot glue gun for this. I glued one of the sticks to the top and used the other 3 (yes, it wasn't a miss type, I said 3) to do what is said in step 3.

xxepicxgamerxx (author)2012-02-23

ummm you only used four yakitori sticks in this picture and i dont know if we need 5 or 4of them

aramey1 (author)xxepicxgamerxx2014-02-05

I made the same mistake. The 5th one is to hold it to the body.

aramey1 (author)2014-02-05

I found scissors to be easier for me. I guess this just depends on which tool you're more comfortable with.

TunaTech (author)2014-01-13

on testing thought it goes upside down, solution a basic eraser weight


TunaTech (author)2014-01-12

awesome design! helping me so much for science olympiad this year thanks!!


mcgenius2000 (author)2013-12-09


I really like your egg drop design and would like to learn more about the physics behind it. How did you figure how to make such an awesome egg drop design like this? If you could provide me with resources that could enhance my physics skills and could provide me with the knowledge necessary on how to build devices like this, it would be greatly appreciated.



(I had a few mistakes on my other comment so I deleted it.)

wkl (author)mcgenius20002013-12-22

Hey! Thanks.

The physics behind this are basically just that you're producing lift with the rotors to oppose gravity (the added benefit is that the spinning tends to stabilize the craft). The net result is that you reach terminal velocity (when the lift force equals the downward force of gravity) very quickly and thus you impact with relatively little momentum.

Hope that helps!

Derp shire (author)2013-09-13

I like potatoes

anthony190255 (author)2013-02-27


csbrocket3 (author)2012-12-11

Thank you for your help! Amazing! :D I am making a Rotor egg drop device for Science Olympiad so this helped a bunch!!

that kind of paper was inventend in our country,philippines

kacee3 (author)2011-04-22

I'm confused. Do we need 3 toile rolls? I cut my first roll length wise and then put the other one inside of it and taped them together... but do I need another one to cut in half??

dancer101 (author)2010-03-13

Thank you so much for creating this! Its amazing! it totally works and is super easy to build. I have to create one of these for my 9th grade Physical Science class and we have to drop it off of our stadium. We also have to write a paper on the laws and forces that are acting on the any ideas?

marty109 (author)2009-11-24

have any clue about what the weight was?

MissNanners (author)2009-05-09

I have done this design, but with smaller rectnagles, and my contraption is spinng crooked and all over the place, also, instead of skewers I used straws, could this be the reason? And, is there a better number of blades, like 4 bug ones, or 8 smaller ones?

wkl (author)MissNanners2009-05-09

hmm. Perhaps the weight isn't evenly distributed? if the straws are bending then that's a problem. You'll want to find something that can support the drag created by the blades. Also make sure that your rotors are all at a 10 to 15 degree angle (from the horizontal). As for the number of blades, you basically just want to create as much drag as possible while keeping a good spin going. I found eight worked well but you can certainly experiment with fewer.

MissNanners (author)2009-05-03
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...
wkl (author)MissNanners2009-05-03

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.

hithere12 (author)2009-04-29

How many grams is thatt?

wkl (author)hithere122009-05-02

sorry i forget.

kaylakat (author)2009-05-01

could you give me an estimate of fall time.

wkl (author)kaylakat2009-05-02

Sorry I have no clue about the time. I do know it easily survived a 5 story fall and seemed to maintain the same speed meaning that it could probably sustain any fall as long as it keeps spinning in a vertical orientation.

JennyROX94 (author)2009-02-16

if you put an egg inside of a sponge and wrap it around in cottonballs and then surround by mesh bath scrubber material it actually works

CameronSS (author)2008-05-25

Nice! The last egg drop competition I was in allowed the use of helium. I got ninth with a super-light structure and a parachute, and places one through eight were taken by kids who did no engineering at all, just attached helium balloons to ziplock bags until they showed under ten grams on the scales, including the egg. Yeah, I'm bitter.

bhunter736 (author)CameronSS2008-05-28

Dont be bitter. Be proud. You have the mental power to work with a great deal more situations. And you also recognize that there is more than one way to do things. The other competitors just took the easy way. Now if it was not supposed to be a competition for the best way to handle the situation then you could be bitter. You didnt use a limited resource wastefully. Your design would hold up over time, the helium would escape the balloons in short order. Imagine if the goal was to air drop the eggs in another country and there was 2 or 3 days in transit and handling before the drop. The balloons would have lost their helium before the drop! Your design would be ready to go. Yours is also re-usable it sounds like. Keep up the good work. : ) PS - You gained a lot from the competition, the balloonists did not. They do not know any more than my 4 year old son about floating stuff. He loves balloons. You just need a competition suited to your higher abilities.

CameronSS (author)bhunter7362008-05-28

:-D I was kind of joking, actually. I'm used to that kind of thing. I have morals, and even when I have an easy chance, I refuse to cheat or copy in class. I then see someone sitting next to me passing their quiz to the person behind them. It's obnoxious, but it's life, and I can't do anything about it. Mostly, the annoying bit was that the first prize was a TI-84. Ninth prize was a few pencils and a keychain.

Rock Soldier (author)CameronSS2009-01-23

What's a Tl-84?

bhunter736 (author)CameronSS2008-05-28

Oh well. A TI-84 would have been nice. At least pencils can do the same thing with the right operator. ; ) Just not as much fun.

CameronSS (author)bhunter7362008-05-28

Actually, I overheard a teacher talking to a judge, saying that they were disappointed that the rules had allowed their students to do so little work and still do well. That was the last year I was eligible, so I haven't checked, but I think they were planning to take helium out of the "permitted" list, as it killed the competition.

Bongmaster (author)CameronSS2008-05-25

the fiends :(

About This Instructable




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