Chapter 24 Space Vehicular Systems

Objectives After reading the chapter and reviewing the materials presented the students will be able to: Identify the structures of various types of aircraft. List several support systems for space vehicles.

Propulsion System Solid Fuel Rocket Engines: contain solid propellant, a combination of fuel and oxidizers, packed into a cylindrical container. The propellant is ignited at the bottom. As the fuel burns, thrust is produced from the bottom of the engine. Liquid Fuel Rocket Engines: These engines use two separate liquids, kept in separate tanks, which are ignited in a combustion chamber. Valves are used to control the flow of each liquid fuel. As propellant is burned in the combustion chamber, it leaves the bottom of the engine as thrust. Launch Vehicle Propulsion: Launch vehicles are used to take spacecraft and satellites into orbit and outer space. By using stages (several propulsion systems on top of each other), the vehicle can get rid of unneeded mass during flight. Space Shuttle Propulsion: The shuttle has 3 main propulsion components: the main engines (3), the solid rocket boosters (2 SRBs), and one external tank (ET). During takeoff the engines receive needed fuel from the ET. Two minutes after launch, the SBRs are empty, and released from the shuttle. They are recovered and reused.

Guidance Systems Navigation is being able to establish the spacecraft’s location in space. Triangulation (three radio antennas located on three continents around the earth) is used to compute the location of a space craft or other object in space. Guidance is determining if the vehicle is in the correct place and figuring how to change its location if not correct. A flight plan is a detailed account of the path the spacecraft is supposed to travel.

Control Systems Unmanned Spacecraft: Satellites and space probes must be controlled from ground control centers. Thrusters can be used to rotate the satellite into position. Reaction wheels (large rotating wheels) can generate momentum and spin the spacecraft. Manned Spacecraft: Two types of manned spacecraft are space shuttles (fig 24-12, page 582) and manned maneuvering units ( MMUs). On space shuttles, flaps on the rear of the wings control pitch and roll. A rudder on the tail fin controls yaw. Once outside the earth’s atmosphere, the above methods cannot be used. The nozzles surrounding each of the main engines can be rotated. By directing the flow of escaping gas, the engines are able to steer the space shuttle. MMUs use small jets that emit nitrogen gas. The escaping gas provides an action that causes a reaction in the opposite direction.

Suspension Systems The only time a space vehicle uses a suspension system is when it exits and reenters the earth’s atmosphere. One suspension system used on space shuttles is the orbiter wings. The wing of the orbiter serves two purposes. The first is to suspend the shuttle in the air as it is guided back to earth during reentry. The second function of the wing is to serve as a thermal protection system (over 2,000 degrees F on reentry). Another space shuttle suspension device is the landing gear, much like the one commercial aircraft use.

Structural Systems Unmanned Spacecraft: The main structure (bus) material is most often an aluminum alloy, titanium alloy, or magnesium alloy. Composite materials, such as Kevlar resins are becoming more popular, but they are often used in combination with an alloy. Components attached to the main structure include solar panels, antennas, guidance and navigation equipment, measurement instruments, and monitoring devices. Manned Spacecraft: The International Space station (ISS) will be over 200 feet long and 350 feet wide. The aluminum trusses will contain the cooling system and solar arrays needed to maintain the ISS. It will also have living areas and research areas for crews. The shuttle orbiter makes use of construction techniques found in the aircraft industry. The SRBs (solid rocket boosters) are constructed of a series of hardened steel rings. The booster sections are attached with high strength steel pins. The resulting joints are sealed with rubberlike O-rings and then covered with a fiberglass tape. The SBRs are reusable. The ET (external tank) is the largest part of the launch vehicle. It holds the liquid fuel (oxygen and hydrogen) the main engines will use. It burns up during reentry to the earth’s atmosphere.

Support Systems NASA (National Aeronautics and Space Administration) has a number of space centers, research centers, and test facilities that conduct research and tests and prepare space craft for flight. The most well known centers are Kennedy Space Center in Florida (Orbiter Processing Facility where the orbiter is examined and reconditioned and Vehicle Assembly Building where the SRBs and ET are attached)and Johnson Space Center in Texas (Mission Control Center that directs the actual liftoff). Unmanned spacecraft are supported by NASA’s DSN (deep space antennas). The antennas are in California, Spain, and Australia. The DSNs are able to monitor and correct trajectories, as wll as collect scientific data the space craft is sending. Private companies also provide support to maintain and improve existing space craft and research ways to enhance space travel.

Summary Solid Fuel Rocket Engines: contain solid propellant, a combination of fuel and oxidizers, packed into a cylindrical container. Liquid Fuel Rocket Engines: These engines use two separate liquids, kept in separate tanks, which are ignited in a combustion chamber. Space Shuttle Propulsion: The shuttle has 3 main propulsion components: the main engines (3), the solid rocket boosters (2 SRBs), and one external tank (ET). Guidance is determining if the vehicle is in the correct place and figuring how to change its location if not correct. Unmanned Spacecraft: Satellites and space probes must be controlled from ground control centers. The International Space station (ISS) will be over 200 feet long and 350 feet wide. The SRBs (solid rocket boosters) are constructed of a series of hardened steel rings. The booster sections are attached with high strength steel pins. The resulting joints are sealed with rubberlike O-rings and then covered with a fiberglass tape. The SBRs are reusable. The ET (external tank) is the largest part of the launch vehicle. It holds the liquid fuel (oxygen and hydrogen) the main engines will use. It burns up during reentry to the earth’s atmosphere. NASA (National Aeronautics and Space Administration) has a number of space centers, research centers, and test facilities that conduct research and tests and prepare space craft for flight.

Home Work 1.What are the 3 main propulsion components of the shuttle? 2.What are the 2 purposes of the wings of the shuttle orbiter?