When a skydiver falls belly first they have the most drag on their body as possible, which means their terminal velocity is at a minimum. Starship’s maneuver can be compared to that of a skydiver during freefall. When air pressure increases and the atmosphere gets thicker, terminal velocity gets slower, because an object experiences more drag. Terminal velocity changes as the conditions around the object change. The definition of terminal velocity is: the maximum velocity an object reaches as it falls through a fluid, such as air, or when the downward force or gravity equals the force of drag. As a general rule, the lower the rocket’s terminal velocity is, the later it has to perform its landing burn, because the engines don’t need to burn off as much velocity anymore. The other purpose is to control the peak temperature and orientation of Starship during orbital reentry. One purpose of the belly flop maneuver is to scrub off and reduce as much velocity as possible passively. Terminal Velocity during a Rocket Landing Lighting the engines at a horizontal orientation produces a significant amount of horizontal velocity, which will then lead to the rocket intentionally over rotate to cancel out the injected horizontal velocity. The drain valves on the header tanks are positioned at a slight angle to aid in the maneuver. These header tanks are located in the nose portion and in-between the two main tanks of Starship, they remain nearly full until landing maneuver. Since the feed lines from the tanks to the Raptor engines are located on the bottom of the rocket, during the belly flop, the engines would receive mostly air if they tried to pull propellant from the main tanks. This is because the rocket is being slowed down by the ever thickening atmosphere, which pushes the propellant down on the belly. (Credit: C-Bass Productions) Propellant Settling on Starship’s Bellyĭue to the horizontal orientation of the rocket, the propellants settle on the belly or windward side of Starship. If they continued to take liquid methane (CH 4) and liquid oxygen (LOX) from the main tanks, the engines would end up ingesting air, which could result in a RUD (Rapid Unscheduled Disassembly) of the engines. The reason behind this is because the engines cannot take in any air. Sometime in the future, SpaceX might add hot gas thrusters to farther aid in the rotation.Īs a result of Starship igniting the Raptor engines horizontally, the engines must receive the propellent from special tanks called header tanks. This combined with the firing Raptor engines cause the tail section to rotate under the nose, making the rocket vertical. When the rear fins retract and tuck in, the nose portion experiences a substantially higher amount of drag compared to the tail section. At around 500 m (1640 ft) in altitude, it will light two Raptor engines, gimbal them full tilt, fold in the rear flaps, and swing from horizontal to vertical so it can land tail down on its landing legs. Starship begins by falling out of the sky, belly first, to expel the greatest amount of velocity as physically possible while in freefall. The Starship landing maneuver is a new and unique style of landing a rocket. “The Definitive Guide To Starship: Starship vs Falcon 9, what’s new and improved?” Starship’s Transition from Belly Flop to Tail Down In a previous video and article, Everyday Astronaut covered and answered questions all about Starship. Different options of engine combinations at the point of landing.This article will address the different aspects that affects Starship’s landing maneuver: Should SpaceX just switch to a Falcon 9 first stage style of landing?.Are the experienced G forces reasonable?. Why don’t they just start the flip maneuver earlier and ensure there’s enough time to make corrections if something goes wrong?.Will this ever be safe enough for humans?.Why are they doing the flip maneuver so close to the ground?.The landing attempts so far have raised a lot of questions: It is a 9 m wide, 50 m tall rocket that falls out of the sky horizontally, before flipping and landing vertically. Starship is performing maneuvers that have never yet been attempted.
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