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  • Tee Shirt Launcher

    Here some pics of that remote control t-shirt launcher that was in the pic with the injection molding machine at TechShop.

    It was built with the kids at Tigard High School Robotics. 9 barrels, can fire 3 shirts in each barrel. The elevation is with an old seat adjuster from a chrysler town and country that was a warranty reject.



    More Pics at: http://www.flickr.com/photos/techshoppdx/






  • #2
    Here's a soundtrack for viewing those photos, salute to the t-shirt launcher inventor: http://www.youtube.com/watch?v=1b3pJYfv5eg

    -Matt

    P.S. How many feet per second do the shirts go?

    Comment


    • #3
      That audio is great!

      Not sure what the muzzle velocity is. Thought about rigging up some sort of chronograph.

      It will launch a standard shirt about 150 feet. Pepsi cans much further!

      Comment


      • #4
        How about a wet t shirt? Tomato perhaps?

        You don't need a chronograph. Set the launcher to fire parallel to the ground at a height of one meter and fire something that has negligible retarding effect by the air such as the Pepsi can. Measure the distance until it hits the ground in meters. Multiply by 2.214 and you have the muzzle velocity in meters per second.

        You can then extrapolate by the ratio of masses from the tee shirt and the pepsi can the approximate muzzle velocity of the tee shirt.
        Last edited by Evan; 05-09-2009, 04:31 AM.
        Free software for calculating bolt circles and similar: Click Here

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        • #5
          Or find any decent paintball field. They'll typically have either some radar-based chronies or at least a breakbeam light-sensing type.

          We chronied a potato cannon many years ago- the typical PVC and hairspray style. It'd lob a potato about 200 yards, but at "only" around 150fps muzzle velocity. (That was using a high-end radar chronograph.)

          I'd wager this shirt cannon is in that same ballpark.

          ... Are those socket-wrench U-joints on the driveshafts...?

          Doc.
          Doc's Machine. (Probably not what you expect.)

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          • #6
            yep, they are.

            If they break home depot will replace them!

            Comment


            • #7
              lIt shoots at 180 fps. (according to the bud audio)
              - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
              Thank you to our families of soldiers, many of whom have given so much more then the rest of us for the Freedom we enjoy.

              It is true, there is nothing free about freedom, don't be so quick to give it away.

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              • #8
                It doesn't matter what device you use to throw something, the velocity will be the same for the same angle and range if air resistance is neglected. At these low velocities something dense like a soda can or a tomato will have the same trajectory if you throw it, kick it, bat it or shoot it. Since the attraction of gravity is the same in all cases basic grade 9 calculus applies. That's why it can be boiled down to such a simple term if you fix the other variables as I offered above.

                BTW, if you don't want to use metric then place the device 39 inches above the ground and measure the distance in feet. Then multiply by 7.26 for feet per second.
                Free software for calculating bolt circles and similar: Click Here

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                • #9
                  That is Ballistics 101, and while interesting, it is of only passing value. To be meaningful, the range must be dead level and the starting trajectory ie. the bore of the barrel, must be parallel to the ground of the range. Any elevation or depression will skew the results. If these requirements are satisfied, it still only yields an average velocity, not muzzle velocity.
                  Jim H.

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                  • #10
                    Originally posted by JCHannum
                    That is Ballistics 101, and while interesting, it is of only passing value. To be meaningful, the range must be dead level and the starting trajectory ie. the bore of the barrel, must be parallel to the ground of the range. Any elevation or depression will skew the results. If these requirements are satisfied, it still only yields an average velocity, not muzzle velocity.
                    you guys should debate it for the next thirty pages

                    Comment


                    • #11
                      That is Ballistics 101, and while interesting, it is of only passing value.
                      I learned ballistics in grade 9 as one application of calculus. Calculus is the mathematics of motion over time.

                      Physics of trajectories
                      A familiar example of a trajectory is the path of a projectile such as a thrown ball or rock. In a greatly simplified model the object moves only under the influence of a uniform homogenous gravitational force fieldForce field (physics)
                      Originally a term coined by Michael Faraday to provide an intuitive paradigm, but theoretical construct , for the behavior of electromagnetic fields, the term force field refers to the Line of force one object exerts on another object or a collection of other objects....

                      This is the focus of the discipline of ballistics
                      Ballistics is the science of mechanics that deals with the flight, behavior, and effects of projectiles, especially bullets, gravity bombs, rockets, or the like; the science or art of designing and accelerating projectiles so as to achieve a desired performance....

                      Newton's theory later developed into the branch of theoretical physics.
                      Theoretical physics employs mathematical models and abstractions of physics in an attempt to explain experimental data taken of the natural world....
                      known as classical mechanics.

                      Classical mechanics is used for describing the motion of macroscopic objects, from projectiles to parts of machinery, as well as astronomical objects, such as spacecraft, planets, stars, and galaxies....

                      . It employs the mathematics of differential calculus.
                      Differential calculus, a field in mathematics, is the study of how functions change when their inputs change. The primary object of study in differential calculus is the derivative....
                      (which was, in fact, also initiated by Newton, in his youth).
                      http://www.absoluteastronomy.com/topics/Trajectory

                      To be meaningful, the range must be dead level and the starting trajectory ie. the bore of the barrel, must be parallel to the ground of the range. Any elevation or depression will skew the results. If these requirements are satisfied, it still only yields an average velocity, not muzzle velocity.
                      I believe I mentioned that. I used fewer words though.
                      This is a Tee Shirt launcher, not a precision target rifle. The results obtained will be accurate to within ten percent or so without taking any special measures. That is good enough. Repeatability will be considerably better as long as the same setup is maintained.

                      As I said, the effects of air resistance at these low velocities are negligible on an object that is reasonably massive compared to it's volume. The terminal velocity of a full Pepsi can will be somewhere over 100 miles per hour which is approximately 146 fps.
                      Free software for calculating bolt circles and similar: Click Here

                      Comment


                      • #12
                        Originally posted by Evan
                        The terminal velocity of a full Pepsi can will be somewhere over 100 miles per hour which is approximately 146 fps.
                        Based on what information?
                        Jim H.

                        Comment


                        • #13
                          Originally posted by mochinist
                          you guys should debate it for the next thirty pages
                          Wait, are we done panicking about Swine Flu yet?

                          Jerry: Great Job! That looks like a blast to build and operate!
                          "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                          • #14
                            Originally posted by mochinist
                            you guys should debate it for the next thirty pages

                            *passes over popcorn*

                            Beer is the cooler under the mill.
                            This product has been determined by the state of California to cause permanent irreversible death. This statement may or may not be recognized as valid by all states.
                            Heirs of an old war/that's what we've become Inheriting troubles I'm mentally numb
                            Plastic Operators Dot Com

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                            • #15
                              Originally posted by Liger Zero
                              Beer is the cooler under the mill.
                              Ah, so that's what the door in a turret mill's base is for!
                              "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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