Fire away! project

Description of our trebuchet

Our Model of a trebuchet is made with a wooden base, wooden legs, and a arm made from a pvc pipe. Along with the arm we had a cradle connected to it made from plastic to give the release a better angle. The whole catapult never goes over the 1 meter in size. Our projectile we used was a piece of clay that we put in the cradle. We used rubber bands connected to our base held on by nails to create tension before being released so then the arm would have more power when pulled back.

The selling points

One of the best things about our catapult is that it can launch our projectile a far distance consistently. Another big advantage our catapult has over others is because we used a pvc pipe for the arm. This is important because it is lightweight and hollow on the inside making our projectile fly farther.

Our 8 Modifications

1.Using more rubberbands

By using more rubberbands it creates more tension before the release therefore making the projectile go further.

                                      2.    More stable legs

By using more stable legs we can reuse this catapult even more because they wont shake and ruin the screw connected to it. Not only that but this would also make our projectile go more straight instead of to the left or right.

                                   3.  Straighter launch angle

Having a more straight launch angle would make our projectile go straight with would make the distance go further becuase it isnt going to the sides.

4. Farther back Rubberband

By making the rubber band farther away on the base it creates more tension and power aswell for our projectile to be launched

                                                5. New arm ratio

With a change in our arm ratio we now have it so then both sides of the arm do an equal amount of work which makes it a lot less likely to break.

6. Thicker rubber bands

By using thicker rubber bands it gives more potential energy when stretched out which from there would make our projectile go further

7. Change cradle angle

By changing the angel that the cradle is the release angle is changed with it which means that it will be released at a better angle to maximize distance

8.  Reduce friction from axel and arm

By doing this this the arm can move with out having any friction slowing it down and shortening the distance our projectile goes.

Technical specifications

Mass of our projectile: 0.015kg

Horizontal distance: 25m

Time in air: 1.75 seconds

Vertical distance 3.773m

Horizontal velocity: 14.3 m/s

Vertical velocity 17.15 m//s

Total velocity: 25.53 m/s

Release angle: 50 degrees

Spring constant:140N

Initial spring Potential energy: 51.25N

Kinetic energy of ball 9.2J

Percent energy converted:18%

                                                                       CER POSTER