SuomiKaataa2

A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of artificial objects are in LEO. LEO is at an altitude less than about one third of the Earth's radius, or about 2000 km.  No human spaceflight took a place beyond LEO except of the Apollo program, see  Apollo program  overview. LEO is the easiest orbit to get to and stay in.  Low Earth Orbit (LEO) and Geosynchronous Orbit (GEO)  The mean orbital velocity needed to maintain a stable LEO is about 7.8 km/s, which is 28,000 km/h.  This speed depends on the exact altitude of the orbit. For example, if we calculate the orbital speed for a circular orbit of 200 km, the orbital velocity is 7.79 km/s. For example, for a higher 1,500 km orbit the velocity is reduced to 7.12 km/s.  The pull of gravity in LEO is only slightly less than on the Earth's surface. This is because the distance to LEO...

The hypergolic rocket engine AJ10 has been used to propel upper stages of several launch vehicles, such as Delta II and Titan III. Some variants were used as the service propulsion module for the Apollo Service Module, and in the Space Shuttle Orbital Maneuvering System.  AJ10-118K; source: wiki The AJ10-138 engine was originally developed for Vanguard and Able, and was flown from 1964 to 1980. Two of these engines were used in the Titan III GTO Transtage, with thrust uprated from 35 kN to 36 kN, and with a higher specific impulse of 311 s (3.05 km/s). The AJ10-137 engine (91 kN of thrust) was used in the Apollo service module's service propulsion system from first flight in 1966. Trans-Earth injection, from lunar orbit, was the most critical usage of this engine during the Apollo program. This version used Aerozine 50 (a 1:1 mix of UDMH and hydrazine) as fuel and nitrogen tetroxide (N 2 O 4 ) as oxidizer, rather than the previous nitric acid/UDMH. The AJ10-118F engine produced ...

The Space Shuttle orbiter is the spaceplane component of the Space Shuttle, a partially reusable orbital spacecraft system that was part of the discontinued Space Shuttle program. Operated from 1977 to 2011 by NASA. Orbiter is the part of the Space Shuttle system that looks like an airplane. The size is very similar to that of standard medium size commercial passenger jet such as Boeing 747.   Figure 1: Discovery approaches the International Space Station (ISS) on STS-121; source: wiki Six orbiters were built for flight: Enterprise, Columbia, Challenger, Discovery, Atlantis, and Endeavour. Space Shuttle Enterprise (Orbiter Vehicle Designation: OV-101) was the first orbiter of the Space Shuttle system. Rolled out on September 17, 1976, it was built for NASA as part of the Space Shuttle program to perform atmospheric test flights after being launched from a modified Boeing 747. It was constructed without engines or a functional heat shield. As a result, it was not capable of sp...

Forces on rocket is another interesting topic. Aerodynamic forces are generated and act on a rocket as it flies through the air. Forces are vector quantities which means that they both have a magnitude and a direction. Action of force is described both by the magnitude and the direction. In flight, rocket is under influence of four forces: weight, thrust, lift and drag, see  Applications of aerodynamics . Four forces on a rocket; source: NASA The magnitude of the weight depends on the mass of the whole rocket. The weight force is always in direction towards the center of the Earth and acts through the center of gravity, depicted by the yellow dot in the Figure above.  The magnitude of the thrust depends on the mass glow rate though the engine and the velocity and pressure at the rear of the nozzle. The thrust force acts along the longitudinal axis of the rocket.  The lift of a rocket is a side force used to stabilize and control the direction of flight. Lift occurs when a...

Rocket engine nozzle Rockets use nozzles to accelerate hot exhaust to produce thrust as described by Newton’s third law of motion. The amount of thrust which is produced by the engine depends on the mass flow rate through the engine, the exit velocity of the flow, and the pressure at the exit of the engine. The values of these three flow variables are all determined by the design of the nozzle. A nozzle is a device, which is shaped into tube through which hot gases flow. Rockets  nozzle designs typically consist of a fixed convergent section followed by a fixed divergent section. The nozzle configuration is then called a convergent-divergent, or CD, nozzle. In a CD nozzle, the hot exhaust leaves the combustion chamber and converges down to the minimum area, or throat, of the nozzle. The throat size is chosen to choke the flow and set the mass flow rate through the system. The flow in the throat is sonic which means the Mach number is equal to one in the middle of the throat. Downst...