Cake (firework) been blown off by the discharging stars). In a traditional cake, all the candles point upwards; a variant is called the "fan" or "angle" cake. Cakes are one of the most popular types of firework, as they can create spectacular and long-lasting effects from a single ignition while minimising safety concern. In the UK, the reclassification of aerial shells to Category 4 has popularised cakes as a method for achieving similar effects while staying within safety guidelines, particularly by firing multiple candles at the same time. Cakes vary greatly in size, weight and duration. Some last only a few seconds
Rocket engine Rocket engine A rocket engine uses stored rocket propellant mass for forming its high-speed propulsive jet. Rocket engines are reaction engines, obtaining thrust in accordance with Newton's third law. Most rocket engines use combustion, although non-combusting forms (such as cold gas thrusters) also exist. Vehicles propelled by rocket engines are commonly called rockets. Since they need no external material to form their jet, rocket engines can perform in a vacuum and thus can be used to propel spacecraft and ballistic missiles. Compared to other types of jet engines, rocket engines are by far the lightest, and have the highest thrust,