Water Rocket Parachutes

 - by KitchenPantryScientist

For some serious outdoor fun, try a little rocket science and parachute engineering. Click here to watch a demo and segment on rockets I did for Kare11 Sunrise (the top video on the page is metamorphosis, the bottom one is rockets)!

NASA works hard designing new parachutes to slow the descent of spacecraft so they aren’t damaged when they land on distant planets. It can be tricky, since parachutes depend on air resistance to slow the descent of their loads, and many planets have very little atmosphere.

Here on Earth, you can design and test parachutes for our terrestrial atmosphere using produce bags, glue dots and string attached to a water rocket, to see what works best! Click here for detailed instructions on making a water rocket!

You’ll need a bike pump, an empty 1L plastic bottle, a cork that fits the bottle, cut in half, an inflation needle, lightweight plastic bags, like produce bags, string or twine, and glue dots (optional)

1. Make a water rocket. Directions for assembling the rocket are here: http://kitchenpantryscientist.com/simple-water-rockets/ 

2. Cut produce bags into large squares.

3. Cut 4 or more strings to attach the produce bag parachute to the rocket. You can use kitchen twine, yarn or embroidery thread.

Use glue dots to attach your parachute to strings.

Use glue dots to attach your parachute to strings.

4. Use glue dots to firmly  attach the strings to the plastic, and duct taping the parachutes onto 1 liter bottles. If you don’t have glue dots, punch holes in the corners of your parachute and tie the string on.

5. Securely attach the strings on your parachute to the bottom of the 1L bottle with duct tape.
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Safety goggles are required for this experiment!

6. Once you’ve made a parachute and attached it to a bottle, fill the bottle with 3-4 inches of water and plug it with a cork that’s been cut in half and impaled with a ball inflation needle.

Point the bottle away from you, with the cork down and the bottom up!

Point the bottle away from you, with the cork down and the bottom up!

7. Put on your safety goggles, attach the needle to a bike pump, set the bottle in a box or container so the bottom of the bottle is pointing up and away from you with the parachute positioned over the bottle (see photo), and start pumping!

What happens? As air pressure builds in the bottle, it pushes the cork and water down towards Earth, and sends the rocket in the opposite direction. Gravity pulls the empty bottle back to Earth, but the open parachute attached to it has a large surface area, which increases air resistance and adds a huge amount of drag to the falling rocket, slowing its fall. 

The shape of the parachute, the length of the strings, and even the material the parachute is made from all affect how air moves around it and how well it slows the fall of an object. Adding holes to the parachute to help control air movement can also affect how well it works. It may take several tries to get your parachute to work, so don’t get frustrated! Just keep re-engineering it!

Have fun rocketing!

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