DIY Parachutes: Exploring Air Resistance and Terminal Velocity
At-a-Glance Experiment Overview
| Category | Details |
|---|---|
| Mess Level | 3/5 (Some string tangles and outdoor cleanup) |
| Time Needed | 20–30 minutes |
| Estimated Cost | $0–$3 |
| Safety Gear | None required (supervision near stairs or balconies) |
| Best For | Young and Middle kids |
| Core Concepts | Air resistance, terminal velocity, drag forces |
| Indoor/Outdoor | Both (outdoor drop zones work best) |
Yes! You can build a working parachute from a grocery bag, some string, and a small toy in about half an hour. This hands-on experiment teaches kids how air resistance slows falling objects, and why skydivers don't splat when they land.
What You'll Discover
When you drop a parachute from a height, gravity tries to pull it down while air pushes back up against the canopy. The bigger the canopy, the stronger that upward push. Eventually, the two forces balance out, and your parachute falls at a steady speed instead of speeding up. Scientists call that steady speed "terminal velocity," and it's the reason a leaf floats gently to the ground while a rock thuds down fast.
In this experiment, you'll design, build, and test your own parachute. You'll see how canopy size, string length, and even tiny holes affect how quickly (or slowly) your toy pilot lands. Plus, you get to drop things from safe heights, which kids love.
What You'll Need
Gather these materials before you start:
- Canopy material: A plastic grocery bag, a lightweight kitchen trash bag, or a square of thin fabric (napkins or bandanas work well)
- String or yarn: About 2–3 feet total (any color is fine)
- Small toy figure: A LEGO minifigure, a plastic army man, or a small stuffed animal
- Scissors: For cutting the canopy and string
- Ruler or tape measure: To measure string lengths
- Optional: A hole punch, markers for decorating, or tape to reinforce corners
You likely have most of these items around the house, which keeps costs low.
Step-by-Step: Building Your Parachute
Step 1: Cut Your Canopy
Lay your plastic bag flat on a table. Cut out a square that measures about 12–16 inches on each side. (Younger kids may want to start with a smaller square, around 10 inches, which is easier to handle.)
If you're using a trash bag, unfold it completely and cut a single-layer square. Don't worry about perfect edges, parachutes are forgiving. A slightly wonky square still catches plenty of air.
Adult help: Scissors can be tricky for younger hands. Grown-ups can do the cutting, or supervise closely.
Step 2: Reinforce the Corners (Optional but Helpful)
Fold a small piece of clear tape over each corner of your square. This makes the corners stronger and prevents the string from ripping through the plastic during drops.
If you're using fabric, you can skip this step, cloth tends to hold up better than plastic.
Step 3: Attach the Strings
Cut four pieces of string, each about 12–14 inches long. (Measure them so they match, uneven strings cause wobbly landings.)
Tie one string to each corner of your canopy. If you reinforced the corners with tape, poke a small hole through the tape and thread the string through before tying a knot. If you're working with fabric, tie the string directly around the corner and pull snug.
Tip: Use a simple overhand knot or double knot. You want it tight enough that it won't slip off during flight.
Step 4: Connect the Strings to Your Pilot
Gather the four free ends of the strings and hold them together. Tie them all around your toy figure's waist, chest, or a sturdy part (like a LEGO minifigure's torso). Make sure the knot is secure, loose knots mean your pilot might "bail out" mid-flight.
Stand up and hold the canopy above your head. The toy should dangle below it, and all four strings should be roughly the same length. If one string is way longer than the others, untie it and adjust.
Step 5: Test Your Drop Zone
Find a safe spot to drop your parachute. Good options include:
- A staircase: Stand at the top and drop it into the stairwell (check that no one is walking below)
- A second-story window or balcony: Make sure you're dropping into a yard or driveway, not onto people or pets
- A sturdy stepladder: Even a 5–6 foot drop shows how parachutes work
Safety note: Check your drop zone before every launch. Make sure no one is standing underneath, and avoid dropping near breakable objects or busy areas.
Step 6: Drop and Observe
Hold your parachute by the canopy (not the toy). Crumple it loosely in one hand, then toss it gently upward or release it straight down. Watch what happens.
Does the canopy open right away, or does it flutter for a second before catching air? How fast does the toy fall compared to dropping the toy by itself (no parachute)?
Try dropping the same parachute three or four times. Notice whether it lands the same way each time or if the canopy sometimes collapses or twists.
The Science: How Air Resistance Slows Things Down
When you drop an object, gravity pulls it toward the ground. The object speeds up as it falls, at least at first. But air isn't empty space. It's made of tiny molecules that push back when something moves through them. That push is called air resistance or drag.
A parachute works by spreading out a big, lightweight surface (the canopy) that catches a lot of air. All those air molecules press upward against the fabric, creating a strong drag force. The bigger the canopy, the more air it catches, and the slower the parachute falls.
What Is Terminal Velocity?
At first, gravity wins the tug-of-war, and the parachute speeds up. But as it falls faster, air resistance grows stronger. Eventually, the upward push from air resistance equals the downward pull of gravity. When that happens, the parachute stops speeding up and falls at a constant speed. Scientists call that steady speed terminal velocity.
A small parachute might reach terminal velocity at, say, 15 feet per second. A larger parachute might reach it at only 5 feet per second. That's why bigger parachutes give gentler landings: they have a lower terminal velocity.
Real skydivers use the same idea. Their parachutes are huge (often 200–300 square feet), so their terminal velocity is slow enough to land safely on the ground.
Try These Variations
Once you've built a basic parachute, experiment with different designs:
Change the Canopy Size
Cut a second canopy that's twice as big (or half as big) as your first one. Attach the same toy and drop both parachutes from the same height. Which one lands first? Which one drifts more as it falls?
Prediction challenge: Before you drop them, guess which parachute will have a slower terminal velocity.
Add a Guiding Hole
Use scissors to cut a small circle (about the size of a quarter) right in the center of your canopy. This is called a "guiding hole," and it helps the parachute open smoothly without jerking or spinning.
Drop the parachute with the hole and compare it to one without a hole. Does the hole make the descent faster, slower, or more stable?
Adjust String Length
Try making the strings shorter (6–8 inches) or longer (18–20 inches). How does string length affect how quickly the canopy opens? Does it change how stable the parachute is during flight?
Test Different Materials
Build parachutes from a napkin, a bandana, a coffee filter, or a piece of plastic wrap. Which material catches the most air? Which one tangles or collapses the easiest?
Why This Experiment Matters
Understanding air resistance isn't just for toy parachutes. Engineers use the same principles to design:
- Braking parachutes for race cars and jets
- Drag chutes for spacecraft re-entering the atmosphere
- Emergency parachutes for small aircraft
- Delivery drones that need to land gently
Even things like bike helmets, car shapes, and windbreaker jackets are designed with air resistance in mind. The more you understand how air pushes back, the better you can design objects that move through it efficiently: or slowly, when you want them to.
Frequently Asked Questions
Q: Why does my parachute sometimes not open?
A: If the strings tangle or the canopy folds up tight, it might not catch enough air. Try dropping it with a gentle upward toss instead of just letting go. That gives the canopy a moment to spread out before it starts falling.
Q: Can I use a heavier toy as the pilot?
A: You can, but heavier toys fall faster because gravity pulls harder on them. You might need a bigger canopy to slow them down to the same speed as a lighter toy.
Q: What if my parachute spins as it falls?
A: Spinning often happens when the strings aren't the same length or when air flows unevenly across the canopy. Check that all four strings match, and consider adding a small guiding hole in the center to let air escape smoothly.
Q: How high do I need to drop it for the parachute to work?
A: Even a 4–5 foot drop (like from a stepladder) can show how a parachute slows a fall. Higher drops give the parachute more time to reach terminal velocity, so you'll see a steadier descent from a second-story window or staircase.
Q: Can I decorate my parachute?
A: Absolutely! Use markers to draw designs on plastic canopies, or pick colorful fabric for cloth parachutes. Just keep decorations lightweight: heavy paint or stickers can weigh down the canopy and make it fall faster.
Disclaimer
This experiment involves dropping objects from heights such as staircases, balconies, or ladders. Adult supervision is recommended to identify safe drop zones and to help younger children with cutting and tying materials. Check that the drop area is clear of people, pets, and breakable items before each launch. Parachutes are for educational purposes and should not be used for jumping or attempting to slow a person's fall. Results may vary based on materials, canopy size, and environmental conditions such as wind. This activity is intended for fun, hands-on learning and is not a substitute for professional safety equipment.
Ready to send your toy on a safe, floaty adventure? Grab a grocery bag, some string, and a brave little pilot: then head outside to see air resistance in action. Don't be surprised if your kids want to build a whole fleet of parachutes in different colors and sizes. The best part? Every drop teaches them a little more about the invisible forces that shape how things move through the air.