Looking for something exciting to do? Try building a water powered rocket out of a 2 liter soda bottle! This can be completed in less than half an hour with simple household materials.


  • 1 Two liter bottle
  • Cardboard
  • Card stock (or construction paper)
  • 1 Cork
  • 1 Schrader needle (common on most bicycle pumps)
  • Tape


  • Excato Knife
  • Drill (or awl)
  • Scissors
  • Bike pump
  • Marker (or pen)

Step 1: The Cork Stopper

Take a cork and stick it into the soda bottle's opening to make sure that it fits in snugly. The seal has to be tight, so if your cork doesn't fit either find a larger diameter cork, or wrap the cork with tape to increase the diameter.

Cut the cork shorter so that the Schrader needle is longer than the cork, the tip of the Schrader needle has an opening that needs to be exposed.

<p>Hi <a href="https://www.instructables.com/member/Hammock+Boy/" rel="nofollow">Hammock Boy</a></p><p>You describe this as a &quot;water powered rocket&quot;.</p><p>However, this is actually a &quot;compressed air powered rocket&quot;.</p><p>One should ask what the water is used for in these things?</p><p>These rockets go much further by eliminating the water and use only the compressed air in the bottle.</p><p>Here is the physics:</p><p>1. The energy contained in the air is proportional to the volume times the pressure. So the more water in the rocket the less air or energy contained in the rocket.</p><p>2. The lighter the rocket the greater it can accelerate. Water is quite heavy compared to the rocket body. This heavy weigh limits the maximum velocity and consequently the the maximum height the rocket can atain.</p><p>Try a series of test launches with various quantities of water including no water and compare the resultant maximum heights. To be fair, make sure each launch has the same air pressure.</p><p>redrok</p>
<p>Yes you are correct the water only acts as mass for the bottle. The air released is what causes the bottle to fly</p>
Air powered? I don't think air alone would get that bottle very far, do you? Try it without water.
<p>Well by decreasing the container volume, you are increasing the gas pressure (PV=nRT). This means a greater pressure per same amount of pumps</p>
<p>You do need water in these rockets to achieve a maximum height, the water is a mass that you are ejecting. The mass of the water leaving the rocket at speed will give you an equal opposite force pushing the bottle (Newtons 3rd Law). If you only have air in the bottle you will have very little mass, so the rocket won't go far at all. The optimal amount of air/water is something you do need to experiment with (unless you want to get into some maths!)</p>
<p>Here is the physics... Air is not a solid Object, like water. Question, Will a shotgun kick more if there is a slug in it , or just a blank? It has to move the Slug / water, now but that is a Solid Propellant.. well the water is. Check this out .. it will help you to understand more .. </p><p>http://exploration.grc.nasa.gov/education/rocket/BottleRocket/sim.htm</p>
<p>There is a air/water rocket station at OMSI in Portland, Oregon. Filling with some water typically makes them go higher. There may be less energy with water in there, but doesn't the water add thrust and direction?</p>
<p>Maybe the water helps hold pressure better than just air. Prevents some of it from leaking. Maybe if you used a gel of some sort on the cork it would work even better eliminating the weight of the water but letting it seal better also.</p>
<em>Hi redrok,</em>My rocket went higher with the ballast than it did without. the water actually helps increase the weight which increases the momentum gained. This increases the height that the rocket catapults to (law of conservation of angular momentum).<p>SamGeek</p>
Come on Guys, You haven't actually done the experiment of &quot;Water vs No Water&quot;, have you?<br><br>The energy stored in the bottle is solely contained in the compressed air. Since water is incompressible no energy is stored in it.<br><br>The water is simply excess mass. Worse yet the more water volume the less compressed air in the bottle which limits the stored energy.<br><br>redrok
<p>I made one of these years ago but used a crutch bottom on the bottle. The rubber holds tight on the cap and seals again and again. I would think the cork would be destroyed over time.</p>
<p>Although I'm a biology teacher, I would love to do this with students to have them work together and figure out what works best. Simple idea. I love it.</p>
<p>Download Cliff Hight Timer app on your phone for free and start the clock when your rocket start to desend. Easy way to calculate hight of rocket. Add a parashoot to your rocket.</p>
i saw a contest on Japanese TV which was a bottle rocket contest based entirely on distance achieved.<br><br>the winner was a multistage rocket as made here. it had launching tracks and went about 500 feet.<br><br>awesome.
<p>what do you mean 'multistage'? how did they do it?</p>
<p>timers that make the next bottle launch as soon as the previous stage stops</p>
<p>can you please post a link?</p>
<p>Why not use a small hobby type air compressor or portable compressed air tank to pressurize the rocket? All I've ever seen is hand operated pumps.</p>
<p>We use one of the cheap portable jump-starter packs that has a12V lead-acid battery and inbuilt compressor. Works great. I'm planning a smaller unit using a 12V $10 compressor and LiPo battery pack.</p>
<p>You rock ! My son is the same way. I just posted you all over FB and the Geeks that love good geek stuff! Thank you for your awesome ideas! :-) </p>
This is a great fun idea. Thanks
This looks really fun! Good project for holiday break!
For a school science class we made these. I never got to see mine go up though. It went the highest from what I was told, but I wasn't in school that day because unfortunately the night before was my grandfather's memorial service and my mom turned off my brother's and my alarm clock. She didn't want to make us go to school the following day, she thought it would be too hard. Anyway, my science teacher was also the photography teacher, and even though she set my rocket aside so I could see it fly, her photography students threw it out. I've been meaning to make another, but didn't have any way to get it in the air.

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Bio: From solder to zip ties, lead acid batteries and LEDs, and especially Legos, putting things together has always fascinated me. The more challenging the better ... More »
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