The Rocket Launcher is a combo weapon in Dead Rising 2 and Dead Rising 2: Off the Record. It is created by combining Rocket Fireworks with a Lead Pipe. You can shoot fireworks at enemies at a relatively fast rate, clearing hordes of zombies with a short burst. The fireworks need to travel a small distance to "arm up", so make sure you're not firing them point blank or they'll just bounce off an enemy before going off. Getting stuck in an explosion causes you to drop the weapon, so keep your distance.
The Rocket Launcher has a small advantage over most other heavy weapons in that it has no motor that requires starting before it can be used; Chuck can simply pick it up and start firing. Furtherfore, it has an extremely fast rate of fire, allowing Chuck to inflict massive damage in a very short time (it is particularly effective against psychopath Randall Tugman). However, it has the standard disadvantages common to all heavy weapons: it cannot fit in Chuck's inventory, and if he is injured, he drops it.
Both materials needed for the Rocket Launcher can be found inside the Maintenance Room on the South East side of the Silver Strip between the entrances of Royal Flush Plaza and the Slot Ranch Casino.
Once constructed, the Rocket Launcher can be taken to Leon Bell's trailer and combined with a Dirtbike to create a Rocket Launcher Motorcycle.