No lower weight limit.
The engine mount holds the engine in place.
cast aluminum
More bounce per ounce of fuel..
Model rockets can use anything from 1/4A to G engines.Amateur rockets can use up to N engines.Professional rockets have no limit.Each successive engine letter has twice the power of the previous. Assuming Professional rockets start with O engines, the smallest Professional rocket engine has 256 times the power of the largest Model rocket engine. Most will of course be much larger.
Rocket fuel is very heavy and it would take more rocket fuel for the launch to carry the weight of the fuel for retro rockets.
To launch the rocket off the ground and make it go fast.
sail
Hybrid rockets use a hybrid fuel-oxidizer system, usually a solid fuel with a liquid oxidizer. This allows simpler construction and higher reliability (like solid fuel rockets) but retains the ability to throttle the engine on demand or even turn it off and restart it (like liquid fuel rockets).
A squad is a combination of a fire engine and heavy rescue
magnesium is used for airplanes, bombs, photography, engine parts, shuttles and rockets.
Mostly to propel rockets, those going into space, and those carrying explosives.