If we change the shape of the air cannons exit aperture, then the speed of the air coming out will change too, because the different shapes create different vortexes and places for the air to slow down.    We think the circle aperture will produce the fastest air speed, and the square will be the slowest because it has more edges for the air to catch on. We think the triangle air speed with be in the middle.

Our project looks to test the idea of how shapes affect airflow. We reviewed the following sources as part of our research.

Explainsthatstuff.com - Air moves and flows like water does because it is fluid. When air hits different shapes, it can either move smoothly or slow down. Round shapes help the air slide past more easily, but shapes with corners make the air swirl around and slow down.

Nasa.gov - NASA explains that when you pull back a balloon (in a cup‑style air cannon), you pull in air. When you release it, the air rushes forward. The air in the middle travels faster than the air near the edges, which creates a vortex (a spinning ring of air). This shows that air speed depends on how quickly the air is pushed and how evenly the air can escape from the opening.

ScienceWorld.ca explains that the puff of air coming out of a cup‑style air cannon is part of a vortex shaped like a donut (torus). The air rolls from the center to the edges because the air in the middle exits faster than the air around the edges.

ScienceBuddies.org vortex cannon activity explains that air is everywhere, even though we cannot see it, and that you can push air using force. Pulling back on a balloon and releasing it pushes air out quickly. This shows how consistent force makes consistent airflow.

Emily’s Wonder Lab, a netflix show on how building high‑powered air cannons demonstrates how blasts of air through shapes affect how the air comes out.

Controlled

• The area of each shaped exit aperture is the same (19.635)
• The air cannon build & materials used are the same
• The air speed is measured using the same anemometer at measured distances (12”, 24”)
• The air cannon location is the same for each trial
• The pull of the air cannon bungee is limited 2.5” back

Manipulated

• The shape of the exit aperture (circle, square, triangle)

Responding

• The speed of the air coming out of the air cannon

Trial set up: 1.     set up one of the three air cannons on a flat surface.  We used the counter so that the lip of the bucket can push against the counter to ensure the location is consistent for each trial (controlled variable) 2.     from the exit of the air cannon we measured 2 distances and marked them on the counter with a marker (12” and 24”) (controlled variable - distance) 3.     set the anemometer at each measured distance (controlled variable)

Procedure Steps 1.     Set the anemometer at the 12” measured distance (controlled variable) 2.     Starting with the Triangle exit shaped (manipulated variable) air cannon. Stand behind the air cannon holding onto the handle & pull back the bungee to the max allowable distance (2.5”) (controlled variable) and release (controlled variable) 3.     Using the anemometer (controlled variable) record the max air speed 4.     Complete 5 separate air speed measures (controlled variable) to develop an average measure for the Triangle a 12" 5.     Move the anemometer to the 24” measured distance (controlled variable) and repeat the process to pull back the bungee and release 6.     Using the anemometer (controlled variable) record the max air speed 7.     Complete 5 separate air speed measures (controlled variable) to develop an average measure for the Triangle at 24" 8.     Next move to the Square shaped exit air cannon and repeat steps 1-7 9.     Next move to the Circle shaped exit air cannon and repeat steps 1-7

Repeat steps 1-9 until we completed 10 separate trials for each air cannon shape

Materials 3 – 5-gallon buckets 1 – shower curtain 3 – bungee cords 3 – pop bottle tops with lid 1 – packing tape roll 1 – duct tape roll 1 – 1x3 piece of wood 6 – 2.5” wood screws 6 – 1” metal bolts 3 – 1” wood screw 12 – metal washers 6 – metal nylock nuts 3 – plastic knobs 1 – anemometer 3 – shoelaces 1 – fog machine   Tools used – drill, skill saw, propane torch, screwdriver, mini-impact driver, socket wrench, side cutter, jigsaw, framing squares, measuring tape, plyers, nail, scissors, safety glasses

Building the Cannon - our parents helped us with the math so that the exit area of each shape is the same (controlled variable. Plan the exit shapes to make sure they have the same exit area (19.635 inches) controlled variable Circle 5” diameter Area: pi x radius square Area = 3.14 x 6.25 = 19.635inches   Square: Area of a square is length x width Area = square root of 19.635inches Length & Width = 4.431 inches   Equilateral Triangle: Area = square root of 3 divided by 4 x side Side = square root of 4A divided by square root of 3 Side = square root of 4x19.635 divided by square root of 3 Side = square root of 78.54 divided by 1,732 Side = square root of 45.346 Side = 6.734inches    

1 Measure and cut the different shapes into the bottom of the buckets ensuring they match the measurements based on area calculations below

2 Cut the wood to build the handle support

·       Line up the wood to the bucket and measure the support to the height of the bucket.  Mark the bucket at the point on the bucket ·       Cut wood to your mark

3 Mark holes on the wood at the top and bottom of the bucket and drill holes though the wood and bucket

4 secure the handle using a screw, washer and nut through each hole

5 Cut wood for the handle

·       Measure the wood to the desired length for the handle, mark the wood ·       Cut wood to your mark\

6 drill holes through handle and support to attach the handle to the support

7 attached the handle to the support using screws

8 Take a soda bottle and measure two inches down from the top of the pop bottle cap.  Mark the bottle with a pen or marker

9 Cut around the bottle at the measured and marked 2”

10 Mark two holes on the cut pop bottle near the top across from each other (one on each side)

11 melt holes through the marked hole using a heated nail.  The melted plastic makes it stronger

12 drill a hole through the middle of the pop bottle and secure knob with a screw though the hole\

13 mark and drill a hole in the bucket 1 ¼” from the bottom on each side

14 drill through the holes

15 take the shower curtain and put the cut pop bottle top in the middle and measure out 8” and mark it all around the top to form a circle.

16 cover the marked circle on the shower curtain with clear tape

17 cut the shower curtain and tape around the circle

18 place the cut shower curtain with attached pop bottle on top of the bucket rim and secure with duct tape

19 take the bungee cord and put it through the outside hole of the bucket and run it through the holes on the pop bottle on the inside.  Feed it out through the other hold of the bucket to the outside and tie off

20 tie a shoelace to the pop bottle pull knob and measure a shoe lace to be 6” on each side

21 fed shoelace through the bucket hole and secure

• The triangle average speed at 24” and 12” is almost the same. Distance does not impact the speed on the triangle
• The square had the fastest speed on the 24” distance
• The circle had the fastest speed on the 12” distance
• Distance matters. For the circle and square, speeds were higher at 12" than at 24" (they slow down as they travel). The triangle was a surprise, the air speed averaged the same at 24" and 12"
• Consistency - The circle has very consistent average air speeds in all trials
• The square was also quite consistent except trial 2&4 which had slower air speeds at 24”
• When we used to the fog machine to put fog into the air cannon only the square and circle shapes created a vortex which could be seen in the form of a fog ring. The triangle did not produce a vortex that can be seen with the fog. This makes sense using the data which shows that the triangle has the lowest air speeds and is the same at both distances.

Data for the trials is in our log book and in the excel sheet attached

We think the experiment worked well and that our controlled variables and numerous trials provided good data to answer our Problem/Question. We did 10 separate trials and averaged 5 data points at each distance to ensure that we had accurate data. Our analysis shows that the square is the fastest at farther distance (24”) and the circle is the fastest at closer distance (12”).

We have attached graphs that show air speeds for each trial / shape

Our hypothesis for the circle shaped cannon was correct when we measured the air speed at 12” but was not supported at 24”

Our hypothesis was incorrect for the square shape as the air speeds at both 12” and 24” were faster than the triangle air speeds.

Our experiment did demonstrate that the exit shape does impact the exit air speeds

Extension - if we did this experiment again these are the things we would do different.

• Test more shapes like oval or rhombus to see how it changes air flow
• Build a fixed cannon holder to ensure it cannot move
• Make the size of the aperture different (smaller / larger)
• Build a fixed anemometer holder
• Try different strength bungee cords to see if the air speeds were impacted
• Test and measure air speeds at more distances
• Test in different air temperatures, outside, inside, cold room, etc.
• Build from different materials like carboard or wood

·       HVAC system – air ducts & vents use different shapes to control airflow and speed ·       Aerodynamics – engineers design planes, cars, trains to be smooth to avoid sharp corners ·       Scientists use mini vortex rings similar to what our air cannons produce to study and understand tornadoes and wind patterns

We used some AI technology to help us come up with ideas on how our experiment could fit into real life and then reviewed our data to see if it supported the real life examples. We think the HVAC example is a good one for our project because we can see this in our houses

Sources of error: ·       While we did calculate to ensure that the area of each shape was the same, there could be slight imperfections in the shapes due to cutting, rough edges, plastic debris that could impact air flow ·       The air cannon could not have been pushed against the counter perfectly each time ·       The bungee elasticity could change due to wear as we did each pull ·       Human error recording numbers incorrectly ·       Temperature of the air in the room could vary ·       Air pressure in the room could vary. Like a heat register turning on ·       Anemometer could move or not be lined up perfectly ·       Calibration of anemometer ·       Placement of anemometer to catch exit airflow

We modified these instructions in order to build our air cannons. TKOR. (2019, May 18). DIY smoke ring shooter! TKOR builds an epic Airzooka, Air vortex cannon, DIY Air vortex cannon [Video]. YouTube. https://youtu.be/BuH-hWrjZmw

Science Buddies’ vortex cannon activity explains that air is everywhere, even though we cannot see it, and that you can push air using force. Pulling back on a balloon and releasing it pushes air out quickly. This shows how consistent force makes consistent airflow. [sciencebuddies.org] Science Buddies. (2020, April 16). Build a vortex cannon! | STEM activity [Video]. YouTube. https://youtu.be/w8j1ZHAhu3g

Emily’s Wonder Lab, show how building high powered air cannons demonstrates how blasts of air through shapes affect how the air comes out. [watch.plex.tv] barisakdemir6comam. (2023). Emily’s Wonder Lab – Se1 – Ep07 – Bowling with Air HD Watch HD Deutsch [Video]. Dailymotion. https://dai.ly/x8esmae

Science World explains that the puff of air coming out of a cup style air cannon is part of a vortex shaped like a donut (torus). The air rolls from the center to the edges because the air in the middle exits faster than the air around the edges. [scienceworld.ca]. Our project looks to test this idea to see how shapes affect airflow — shapes with corners slow air down because they interrupt that rolling motion. Science World. (n.d.). Air cannon. Science World. https://www.scienceworld.ca/resource/air-cannon/

NASA explains that when you pull back a balloon (in a cup style air cannon), you pull in air. When you release it, the air rushes forward. The air in the middle travels faster than the air near the edges, which creates a vortex (a spinning ring of air). [nasa.gov]. This shows that air speed depends on how quickly the air is pushed and how evenly the air can escape from the opening. National Aeronautics and Space Administration. (June 2020). Air vortex cannon (EP‑2024‑11‑624‑HQ). NASA. https://www.nasa.gov/wp-content/uploads/2020/06/air_vortex_cannon.pdf

Woodford, C. (2025). Aerodynamics. Explain That Stuff. https://www.explainthatstuff.com/aerodynamics.html

Our parents - helping build the air cannons because power tools were needed Our parents - helped us make chart and print things for the trifold

Jon's uncle Jeff let the fog machine for us to use so we could see what exit shapes made a vortex