Hot answers tagged

85

I can't speak for why SpaceX made the decision. However, while three legs won't wobble, four legs are less likely to tip over. SpaceX has demonstrated tipping over is a major problem. Dr Peterson of The Math Forum explains... There are different kinds of stability! A three-legged stool is guaranteed not to wobble, because the ends of its legs always ...


29

The dimples on a golfball is structurally the simplest iteration of a vortex generator. Vortex generators are most definitely used in practice to improve aircraft performance. (for some usage examples, see the tag over at Aviation.SE) Turbulence will happen, that's the fundamental nature of aerodynamics. Controlling the transition into turbulence is the ...


22

A stool with three legs that are rigid, are of a fixed length, and have a fixed orientation with respect to the seat of the stool is superior to a chair with more than three rigid, fixed length, fixed orientation legs in one and only one regard. And that one regard is completely irrelevant in the case of landing legs. The landing legs on any landing space ...


7

The actual origin is captured in the question above, so I'll suggest here why the "Skylark" could have been a chosen name. The Lark Ascending is a quintessentially English piece of classical music. Skylarks are a common sight (and sound) in the English countryside (doubtlessly more prevalent back in the 50's than it is now). According to a book on the ...


7

The short answer to your question is GNC (Guidance, Navigation & Control). Mission planning is done based on nominal (normal) performance of all systems launched through a mean atmosphere for the time of year when launch will take place. Depending on how many prior flights have taken place and how much data is available to model a specific vehicle launch ...


6

The main advantage of three legs is on uneven soil: they will always all contact the ground, while with 4 legs one might be up in the air. This isn’t a concern for space x since they land on a flat launchpad or barge. Here the 4 legs increase the stability by increasing the tipping tolerance (as seen is other answers)


6

Here is an attempt at answering this question without recourse to mathematical topology, i.e. using terminology that can be digested by a good physics sophomore. I am describing the outer shape of rockets, not the shape of the various internals (tanks, ducts, wires, combustion chambers...); also, I am consciously simplifying by assuming that apart from the ...


5

Red fuming nitric acid is used as a storable non cryogenic oxidizer. It does not leak, its fumes are vented, I guess to prevent a tank overpressure. From this pdf Problems in Storage and Handling of Red Fuming Nitric Acid So there might be too few NO2 and H2O within the mixture. Adding water would be dead weight, but 2 to 3.5 % should not be a problem.


4

I'm not entirely convinced by the "expendable" argument of the other answers. Let's look at the reasons why you would want to give a name to a craft: When you need to distinguish between more than one vehicle. Any mission with more than one spacecraft (e.g. rendezvous) will need an easy-to-use way to distinguish between the two vehicles. Sure, you can ...


4

Probably the same reason small-holders often don't name their pigs. "The spent lower stage of the ShinyRocket(tm) for project-put-thing-in-sky was jettisoned over the Pacific." Sounds better than if you'd given that same piece of hardware a name. This in keeping with the observation that the bits that weren't expected to meet a fiery end shortly after ...


4

I'll take a whack at it - like CourageousPotato said color code your power/data lines for easier differentiation, and I personally would like to see ground indicators (but may not be necessary). I think breaking out the sensors into a dashed assembly and saying what sensors would be useful. Why do you have a primary and redundant battery for each of your ...


3

When talking about air flow there are some different types/definitions to know: Laminar (uniform, smooth) flow Turbulent flow You're correct when you say This allows the smoothly flowing air to follow the ball's surface a little farther around the back side of the ball, thereby decreasing the size of the wake. The reason that works is because the ...


3

The power supply can be simplified - the data processing / control module is currently supplied by 7.4v at 7.4 amps. Instead of dedicated batteries I'd consider connecting your larger 14v batteries to + and - DC bus bars and having that power the whole system. The control module's power can then come from a 2:1 step down DC transformer connected to that ...


3

It is possible to put Pi type satellites in orbit, but not by flying your own rocket. Cubesats are a class of satellite specifically designed for this sort of thing, where larger payload owners sublet spare capacity on their launchers to smaller organizations, and get placed in orbit before or after the primary payload is delivered. Actually building the ...


2

It is very difficult, and way beyond the ability of hobby rocket science. To achieve orbit, besides large government agencies, there are very few commercial organisations able to put a payload into orbit. For amateurs, they do not get anywhere as close. For example, the European record for a student group is getting a rocket to 30km high. Although this is ...


1

ANone is correct that launchers traditionally haven’t gotten names because they’re expendable; it’s a shame to give a perfectly good name to a rocket that’s going to be in use for less than an hour. Note that the space shuttle orbiters got individual names, because they were flown repeatedly; the expendable booster & ET portions of the space shuttle ...


1

The brilliant and original F-1 Engine Familiarization Manual is a good place to start looking, also for sizes. I'm travelling now; as soon as I'm back (a few days) I can add info from other, offline docs.


1

The answer is YES, shockingly. Most people are likely taught that ion propulsion does not have enough thrust to ever lift its power supply. That used to seem correct. However, I have worked on the problem for 19 years. The result is US Patent No.10,119,527, the Self contained Ion Powered Aircraft. It is a very lightweight ion propelled aircraft that ...


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