Hybrid cannon

A hybrid launcher consists of seven basic elements

   * High pressure combustion chamber
   * Pressure-triggered main valve (usually a burst disk)
   * Barrel
   * Fuel system (usually metered propane)
   * Air filling valve
   * Ingition source
   * One or more pressure gauges

A hybrid is a type of spudgun that combines principles of the combustion and pneumatic spudgun. It uses a pressurized mixture of fuel and air to get more power out of a given chamber volume. In order to fire, the operator first inserts a burst disk, usually consisting of aluminium foil or plastic, between the chamber and barrel. A cam coupling or union is used to hold the burst disk in place. The operator then loads projectile into the barrel, adds fuel to the combustion chamber, and then adds pressurized air. The amount of air depends on how much fuel was added, and is calculated to achieve a stoichiometric fuel/air ratio in the chamber. when the ignition source is triggered, the pressure from the combustion ruptures the burst disk and propels the projectile out of the barrel. The hybrid is capable of higher velocities than a combustion or pneumatic spudgun, projectiles fired by a hybrid have broken the sound barrier (Source). A hybrid using twice as much fuel and air as a comparable combustion gun is said to be using a 2X mix, higher mixtures can be used and will produce even higher pressures. The fuel and air needs to be measured and matched carefully to ensure reliable operation, pressure gauges and fuel meters are used for this. A pressure gauge with a check valve can also be added to record the peak chamber pressure of the gun.

SAFETY: A hybrid is the most dangerous launcher that can be built. It is advised to build with pipe that can handle the high pressure environment (200+ PSI) such as Sch. 80 PVC or metal. Remote ignition is a must, and the limit of a 4x propane/ 4 atmosphere mix should never be breached. If a higher mix is attempted, DDT (deflagration to detonation transition) can occur, causing an extreme pressure spike. Most pipe cannot handle the spike, and will shatter, launching plastic shards every where. Therefore utmost care must be taken with these launchers.