Space Simulator  1.0.9
space flight simulator

Principles of Rocket Design

Leaving aside digital electronics, and exotic composite materials, current rockets are dissapointly similar to Von Braun's A-4 (V2). All current rockets compose a number of stages, each holding two very large ( and very light!) tanks of Fuel and Oxidizer. A set of Turbopumps (not unlike the turbocharger on diesel engines ), force the fuel and oxidizer into the combustion chamber , achieving this by burning a small fraction of fuel/oxidizer generaly in a smaller combustion chamber. The bell shaped (de Lavall nozzle ) is sh] 888aped in a way that the maximum pressure happens at the narrowest point , and hence , pushes the exhaust gases to tremendous velocities. The mass of those gasses ( both are termed propellants ) at those speeds, create a reaction force (thrust )that pushes the rocket fordward.

Ideally an ideal rocket would have very little mass and hold huge values of propellant . However this is not possible. The engines, the tanks ,the structures, are basically dead-weight. As the rockets burns its propellants, it obviously decreases significatively its weight , and so need less thrust to keep on accelerating . The engines are big enough (huge! ) to lift a 2000 Tons rocket off the ground .But one couple of minutes later , the same rocket weights only 1000Tons. It could do with smaller rocket engines, smaller tanks, etc.. In other words, the huge rocket engines, turbo pumps, etc.. are oversized by the rocket in mid-flight. Here is when it comes the concept of Staging. It can be derived that it is more efficient to split the rocket in incresigly smaller detachabnle ,parts, to be shred as the velocities increase and the need for thrust is required. Soon it was realized that the optimum number for earth orbit is somewhere beetween 2 and 3 ( the tradeoff beetween carring larger rocket engines and heavier emtier tanks , versus , carring a set of non-pushing (smaller) rocket engines in upper stages.

Outside the Earth's atmosphere ,a rocket will keep oits velocity , affected only by gravitational forces. Most spacecrafts , the ISS, space Shuttle in orbit, Apollo spacecraft on its way to the moon , etc , are NOT using fuel. They are simply coasting .Trust -and hence fuel -is only needed to change the spacecraft's velocity. That brings up to a point :A rocket can only accelerate forward. As rockets have no way of braking , the only way a rocket can slow down ,is rotating the rocket/spacecraft engine side front (as in pointing backwards) and using the engine to accelerate backwards :i.e. recuding the speed.

Fuel in rockets is in extremely limited quantities. The science and art of astronautics and orbital maneuvers consist on finding the more efficient ways to achieve the required mission. In Space-Simulator (the app )you can practice and simulate the outcome of different orbital maneuvers.