Solid and liquid.
The two main types of rockets are liquid fuel rockets, which use liquid propellants like liquid oxygen and kerosene, and solid fuel rockets, which use a solid mixture of fuel and oxidizer. Liquid fuel rockets offer more control and efficiency, while solid fuel rockets are simpler in design and more reliable.
LIQUID PROPELLENTS OR SOLID PROPELLANTS
Only two: solid liquid fuel
what are the two main types of environment
there are two main types the marine and freshwater
Smaller alkanes and alkenes
the two main types of communications are emailing and socialising
The two main types of friction are kinetic and static.
The two main types of economy are Command and Traditional.
The two white Solid Rocket boosters fall back into the sea and are re-used. The main engines are on the shuttle itself which of course is used many times.
what are the two main types of environment
The two main types of creosote are made from wood-tar and coal-tar. Creosote is distilled from these different types of tar and used for varying purposes such as astringent, laxative, and anti-septic.