The Basics of Rocket Propulsion.Part 1.

Wanambwa Zack Nicholas

• Spaceflight usually starts with a rocket launch.

• Once the craft is in space several methods of propulsion exists, including Non-rocket orbital propulsion methods like solar sails, magnetic sails, plasma-bubble magnetic systems, and using gravitational slingshot effects.

• Most crafts use propelant based rockets for propulsion.

Phases Of Space Flight

• Launch Phase

• Cruise Phase

• Encounter Phase

• Extended Operations Phase

We shall concentrate on the launch phase.

Launch Phase

•A spacecraft starts its journey with a Rocket launch.

•A typical rocket like the Saturn V pictured, accelerates the craft to orbital velocity.

•In about 3 minutes they reach speeds of about 10km/s

Rocket Engine

• A rocket engine is a reaction engine that generates thrust from the action of a highly pressurised propelants coming out of a nozzle.

• Can be solid fueled or Liquid Fueled of Hybrid fueled, (Mixture of Liquid and solid fuel)

Liquid Fueled

Liquid Fueled

• A fuel and oxydizer are pumped into a combustion chamber.

• They burn creating a high-pressure and high-velocity stream of hot gases.

• The gases flow through a nozzle that accelerates them further (8,000 to 16,000 kph)

Examples of Fuels Used

• Liquid hydrogen and liquid oxygen - used in the Space Shuttle main engines

• Gasoline and liquid oxygen - used in Goddard's early rockets

• Kerosene and liquid oxygen - used on the first stage of the large Saturn V boosters

• Alcohol and liquid oxygen - used in the German V2 rockets

Advantages of Liquid fuel

1.You can control the amount of thrust by regulating the flow of the fuel and oxidizer to the combustion chamber.

2. You can stop and restart the engines by simple stopping the flow of fuel and restarting it.

Disadvantages of Liquid Fuels

1. Liquid systems are complicated and expensive.

2. Liquid fuels are not very safe, since if you mix too much of the components an explosion could easily result. As a result, liquid propulsion systems are generally not used in situations where solid rocket boosters can suffice

Solid Fueled

• Consists of casing, nozzle, grain (propellant charge), and igniter.

• Propellant burns producing exhaust gases at high velocity

Solid Fuel

• Hot combustion gases are forced out of the hole.

• Simple example of a solid fueled rocket is fireworks.

Solid fueled

• Invented by Chinese in 13th

century.• Most prominently

used as booster for the Space Shuttle launch. (SRB)

• An SRB containing over a million pounds of fuel, burns for about two minutes.

Advantages of solid fuel

1.Simplicity. Since you are basically just putting a match to a pile of highly flammable material, Solid rocket boosters are very simple.

2. Low Cost. The Materials used to create the fuel are relatively inexpensive.

3. Safety. Assuming that the fuel was produced properly, there is no danger of explosion. It will simply burn until it is gone, and then stop.

Disadvantages of solid Fuel

1.Thrust can not be controlled. Once lit, it burns at a steady rate. You can not change this rate without changing the composition of the fuel used

2.Once ignited, the engine can not be stopped or restarted. Any method that might possibly halt the combustion of the fuel would be sure to destroy the remaining fuel.