by Trevor Foss and Beau Bayless
Copyright PyramydAir.com ©2008. All RightsReserved.
Note: The 2008 California Science & Engineering Fair included an airgun-related entry from Beau Bayless and Trevor Foss, eighth-grade students at All Saints' Episcopal Day School in Carmel. Their entry won first place in the Physics & Astronomy section. In a slightly different format than our usual articles, we present their project.
Our objective was to find how changing the air pressure of an air gun affects the average speed of the pellet. We thought that if you double the air pressure, the average speed will double, if you triple the air pressure, the average speed will triple, and so on.
Methods & materials
We constructed an air gun that would shoot pellets at variable pressures through a barrel with a sensor at the beginning and the end. Then we set the pressure to 100 psi and fired the air gun. We recorded the time that the pellet took to pass through the first and second sensors and used the formula Speed = Distance/Time to get the speed. We repeated those steps four more times and averaged the five speeds. We repeated that procedure, increasing the air pressure by 100 psi each time until we reached 500 psi.
|Gas pressure in PSI (pounds per square inch)||100||200||300||400||500|
|Velocity (meters per second)||59.74||78.33||95.10||104.55||106.68|
|Average velocity (meters per second)||58.09||76.63||94.55||105.40||108.87|
Results & discussion
Our graph (above) shows the average speed for each of the gas pressures. For 100 psi, the average speed was 58 meters per second; 200 psi produced 77 mps; 300 psi produced 95 mps; 400 psi produced 105 mps; and 500 psi produced 109 mps. We concluded that our hypothesis was wrong in the saying that doubling the psi would double the average speed. However, we discovered that although increasing the pressure increased the speed as the psi increased, the increase in the average speed decreased.
Data analysis & conclusion
Our experiment investigated how the change in the pressure (pounds/square inch) of an air gun affects the average speed of a pellet. We were trying to find out the relationship between the pressure of the airgun and the average speed of the pellet. Our graph shows the average speed for each of the gas pressures. For 100 psi, the average speed was 58 meters per second, 200 psi produced 77 mps, 300 psi produced 95 mps, 400 psi produced 105 mps and 500 psi produced 109 mps.
Between 100 psi and 200 psi, the average speed increased by 18.6 mps,between 200 psi and 300 psi the average speed increased by only 17.9 mps, between 300 psi and 400 psi the average speed increased by 10.8 mps, and between 400 psi and 500 psi the average speed increased by 3.4 mps. We think we got these results because the greatest change in pressure is between 100 psi and 200 psi. And, 200 psi is twice the pressure of 100 psi, while 300 psi is only 1.5 times as great as 200 psi, 400 psi is 1.3 times as great as 300 psi and 500 psi is 1.25 times as great as 400 psi. So, the increases in pressure were also proportionally less. We concluded that our hypothesis was wrong in saying that doubling the psi would double the average speed.
Our experiment is important because it tells people how fast their airsoft guns shoot. People can use this because most airsoft gun's speed is a guess based on distance and impact. This experiment can tell people how fast their airsoft guns really shoot and if airsoft manufacturers are lying about speed to increase sales.
We think we controlled our variables quite well. We used the same pellet size and mass, the same length of the barrel and the same type of sensors.
One variable that we did not expect was that we had to use a spit wad and a pellet. Since the pellets we used were transparent, the sensors did not register the pellet going past the sensors. To solve this problem, we added a small rolled up piece of paper for the sensors to register the speed. We tried to use the exact same sized wad, but maybe some of the wad sizes could have been slightly off.
If we were going to do this experiment again, we would do 20 shots per pressure and then average them. We would have also made sure that we used the exact same size spit wad with the pellet.
Trevor and Beau used the above tools for their project.
Get FREE shipping on qualifying orders!
Any order $150+ with a shipping address in the contiguous US
will receive the option for free ground shipping on items sold & shipped by Pyramyd Air during checkout.
Certain restrictions apply.
Free shipping may not be combined with a coupon unless stated otherwise.
View Shipping Info
We work hard to get all orders placed by 12 pm EST out the door within 24 hours on weekdays
because we know how excited you are to receive your order.
Weekends and holiday shipping times will vary.
During busy holidays, we step our efforts to ship all orders as fast as possible, but you may experience an additional 1-2 day delay before your order ships. This may also happen if you change your order during processing.
View Shipping Times
It's important to know that due to state and local laws, there are certain restrictions for various products.
It's up to you to research and comply with the laws in your state, county, and city.
If you live in a state or city where air guns are treated as firearms you may be able to take advantage of our FFL special program.
U.S. federal law requires that all airsoft guns are sold with a 1/4-inch blaze orange muzzle or an orange flash hider to avoid the guns being mistaken for firearms.
View Shipping Restrictions
We have a team of expert technicians and a complete repair shop that are able to service a large variety of brands/models of airguns.
Additionally, we are a factory-authorized repair/warranty station for popular brands such as
Air Arms, Air Venturi, Crosman, Diana, Seneca, and Weihrauch airguns.
Our experts also offer exclusive 10-for-$10 Test and 20-for-$20 Service, which evaluates your air gun prior to leaving our warehouse. You'll be able to add these services as you place your order.
View Service Info
Shop and purchase with confidence knowing that all of our air guns (except airsoft) are protected
by a minimum 1-year manufacturer's warranty from the date of purchase unless otherwise noted on the product page.
A warranty is provided by each manufacturer to ensure that your product is free of defect in both materials and workmanship.
View Warranty Details
Didn't get what you wanted or have a problem? We've got you covered! Return any item in new, unopened condition along with its original packaging and any accessories that might have come with your product and receive a refund within 60 days of purchase.
Our customer service team can help determine the best course of action and provide you with some options in the event you're interested in a return.
Learn About Returns
Join the Pyramyd Air mailing list: Our e-mails are filled with new products, deals, sneak peeks, tips and tricks, contests and more - sign up today!
Airgun safety is no accident. You must be 18 years or older to buy any air gun or air rifle in our store.
Text JOIN to 91256 and get $10 Off Your Next $50+ Order.