In five minutes, you can build an air-powered bazooka. The bazooka launches plastic capsules about 100 feet. And with some tweaking, you might stretch that distance quite a bit. Although everything you need to know is in the pictures, the video tells the whole story just as well… If the video is not playing, have a look at it here... All you need to know to build this low-pressure kid's gun is described in the texts, as well as in the comments with the pictures. Have fun building and shooting! But please be careful, don't point your self made bazooka to living creatures. Step 1: Stuff you needShow All ItemsStuff you need:Any model will do. Straight piece of PVC tube, at least 1 meter long. Longer is better (see the text on tweaking)! Inner diameter 35 mm (1.4"). A PVC 3-way junction with an angle of 45°, that fits the straight PVC tube. A projectile: I used the plastic capsule that is inside "surprise-eggs" (see picture). Old school film containers work as well.

Whatever you use, make sure that the projectile's diameter is just a little smaller than the PVC tubes'. A small piece of cardboard (business cards are perfect).« A vacuum bazooka is a pipe-based cannon which uses a vacuum pump (often a vacuum cleaner) to reduce pressure in front of the projectile and therefore propel a projectile as a result of the air pressure acting on its reverse. The concept was originally proposed by Neil A Downie in 2001[1] but many variations have been built since. The vacuum bazooka uses a straight tube which is sealed with a type of bursting disk at the launch end and by the projectile at the other. A tee-piece at the launch end allows application of vacuum. When the projectile is released the air pressure behind the projectile causes it to accelerate towards the vacuum port. When the projectile reaches the vacuum port its momentum causes it to continue past and break through the bursting disk towards the target.[1] A lightweight bursting disk such as a piece of paper can be secured simply by the vacuum action when it is held against the barrel.

Maximum velocity which projectile reached is about 650 mph. The velocity of a projectile in a vacuum cannon can be modeled. The maximum velocity is independent of the projectile mass and barrel diameter. In this model, the maximum velocity is lower than the speed of sound.sharp vacuum cleaner belts Several variations have been developed including a belt fed[3] repeating model.inc robot vacuum cleaner There are many tutorials on how to make a cannon using suction, but it requires too much set up per shot. ear vacuum cleaner canadaWhat I wanted was something that just needs balls fed to it: something my two year old son could use. The cannon design basically is to turn a vacuum motor around and have it blow the balls out.

Most of the tutorial is concerned with how to do this both efficiently and safely. Need: Firm foam (flooring mats used) Bubble wrap or soft foam (like that used in sofas) An old vacuum cleaner A cardboard box about 30 cm for each dimension or larger A grill (to keep fingers out of where they shouldn’t be) Superglue (lots) Hot glue or Caulking Thin, firm and flexible plastic (I used plastic file folders) Step 1: Preparing the vacuumShow All Items« PreviousNext »View All Steps Download from the show Cambridge Science Festival HighlightsWhat you NeedA vacuum cleanerSome pipe a similar size to the vacuum cleaner tube. You can either use plumbing fittings or cardboard tubesSome bubble -wrap or foamSome plasticine, or clay What to doThere are 2 designs for this using either cardboard tubes or waste pipe. Cut a short length from your tube about 10cm long. Cut a hole (or a drill a series of holes making a sieve type arrangement) in the side of the long tube about 5cm clear of the end.

Shape the short piece of tube so it will fit nicely onto the side of the long one. Attach the vacuum hose to the short pipe (this may require more tape) The Waste Pipe Method Attach the length of waste pipe to the T-junction.  If the junction is asymmetric attach it as shown, to reduce the chances of the projectile getting sucked down the side pipe. Attach the vacuum cleaner to the side of the T-junction Make a light projectile by rolling about 5g of plasticine into a sausage. Roll the plasticine sausage in some bubble wrap until it it big enough to fit loosely in your main tube.  This will be your projectile! Use some tape to hold it together. Turn on your vacuum cleaner Put a piece of card over the short end of the tube - the vacuum should hold it in place. Hold the projectile in the other end of the tube. WARNING - If you have a powerful vacuum cleaner the projectile can come out very fast, so DO NOT POINT THE BAZOOKA AT PEOPLE or other breakable objects.

What may happenYou should find that the projectile flies out of the end of the tube at high speed, in a very satisfying manner. Why does it happen?When you attach the vacuum cleaner to the tube it can suck up to about 10% of the air out of the tube.  This may not sound like very much difference, but air pressure is huge.  Air pressure pushes with a force equivalent to 10 tonnes (about the weight of a double decker bus) on every square metre. This means that the air inside the tube is pushing out on the projectile with a force of about 160N (equivalent to 16kg), but the air outside is pushing in with a force of about 180N.  This means that overall there is a force pushing it down the tube of 10-20N (equivalent to 1-2kg). This force is very large for the 10-20g mass of the projectile, so when you let go it will accelerate down the the tube very rapidly. When it hits the card it is going fast enough to knock it off and fly through the air. This is how we suck things up a straw, we reduce the pressure inside our mouths which means that the air pressure pushing down on the drink can push it up the straw into our mouths.