Return of a falcon9 stage fails
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12-11-2018, 10:58 AM
Post: #6
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RE: Return of a falcon9 stage fails
Agreed, it would be good to spend some quality time with rocket scientists. Fortunately, you don't need to, because there are lots of resources out there.
The question of parachutes for SpaceX is almost an FAQ... in fact I see it is in the FAQ. If you play a few rounds of a lunar-lander type game you'll see that burning as late and as hard as you can is the way to use least fuel. The nature of the rocket equation is that using least fuel is very desirable indeed. One way to see this is to time-reverse a landing, using negative fuel consumption. If you took off really slowly, climbing up in the gravity field is just spending fuel unnecessarily. Your rocket is heavy, and you want to get it into free-fall. Imagine a rocket with only just enough thrust to hover: it spends all its fuel and gains no kinetic energy at all. There are also relevant answers on the Space Exploration Stack Exchange:
Why is it even desirable for a spacecraft to land without a parachute? AIUI, the problem with parachutes for re-entry is that by the time you've picked up enough atmosphere to get any useful drag, you're already moving so fast that you will have a serious heat problem - as well as a parachute problem. It might be relevant for SpaceX especially, that they want to get the boosters back to land, or not too far out to sea. So they need to kill a lot of horizontal velocity, fast. See also Having said all that, it seems SpaceX are thinking, or were thinking, of some kind of toroidal ballute for getting the second stage back down for reuse. The second stage is much smaller and will be going much faster, so the tradeoffs are different: no chance to get back to near shore, and a shallow trajectory. |
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Messages In This Thread |
Return of a falcon9 stage fails - compsystems - 12-06-2018, 04:36 PM
RE: Return of a falcon9 stage fails - burkhard - 12-07-2018, 10:17 PM
RE: Return of a falcon9 stage fails - Valentin Albillo - 12-08-2018, 12:39 AM
RE: Return of a falcon9 stage fails - Jim Horn - 12-08-2018, 12:33 AM
RE: Return of a falcon9 stage fails - burkhard - 12-10-2018, 06:59 PM
RE: Return of a falcon9 stage fails - EdS2 - 12-11-2018 10:58 AM
RE: Return of a falcon9 stage fails - burkhard - 12-11-2018, 04:23 PM
RE: Return of a falcon9 stage fails - EugeneNine - 12-11-2018, 12:52 PM
RE: Return of a falcon9 stage fails - burkhard - 12-11-2018, 04:33 PM
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