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vermillioncrown · 2 years

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how do you think flying on a sword compairs to skateboarding/snowboarding? if an expert snowboarder ended up reincarnated do you think they could be a flying prodigy?

oh my god this ask has me doing the equivalent of that stick figure biting into a thing and tearing it apart (in a good way)

yes and no. i think they'd have a leg up and have a higher chance at being a flying prodigy if and only if qi powered flight has aerodynamics involved, and isn't just the equivalent of using your mind to hover through the air.

think of a paper airplane. you can 1) throw the plane and have it glide, or 2) personally hold the plane and move it through the air. both have the paper plane 'moved' but the forces and energy involved are very different.

(1 is more energy-efficient btw, and energy in the physics sense of work)

so let's say 1) is how sword flight works. okay, let's compare it to riding a skateboard or snowboard.

the key difference is that you don't have the ground. that sounds stupid but it matters.

before sword flight, let's think of an aircraft. and before motion, let's think of being still.

without doing work, you can stay in place with a skateboard. why? because you have the ground. the balance of forces is stable without motion. you weight a certain amount and press on the ground, and the ground can push back through the wheels. it's called normal force and we don't have time to go through intro to hs physics. it's why you don't fall through the ground.

snow is a bit different but it still works out. ground is dense enough that you don't compress it like snow, it's solid. snow isn't... purely solid--the individual snow flakes are solid crystalline structures, but it's a collection of these tiny little solids that can move if you press them together. we can call the collection of snow, not an individual snow unit, a fluid rather than a solid. fluids do not hold their shape if you use an outside force on them. from basic chem, we have gas, liquid, solid states, so fluids encompass gas and liquids (with so many caveats but again y'all aren't signing up for intro to viscous fluids)

but let's treat snow like a very dense fluid. the entire snowboard is distributed over the snow rather than the tiny wheels of a skateboard. you can already intuitively imagine that if you put a skateboard on snow, it'd sink until the flat part. the density of matter is what affects how it can 'push back' at things. ground is super dense compared to snow, so little wheels can stand on it vs snow needing a huge distribution to push back the same weight (snow shoes).

air is much less dense than snow. with a density of 1.225 kg/m^3, let's say you weigh 50 kg (~110 freedom units). using basic ass Pressure_liquid=density*acceleration_gravity*height and Pressure_you=mass*acceleration_gravity/Area -> we want P_liquid = P_you -> solve for Area... to stay still at a height of 10 meters, you'd need a 'board' of 4.082 m^2. or about 44 sq ft. but! that board will also have a weight, so you need something bigger, and bigger,

there's nothing out there that can support you, and be lightweight enough to not outpace the pressure that air can exert back to keep you in place. so how do you stay in the air?

two ways. either hover like a helicopter, continuously moving upwards to counteract gravity... or you continuously move forward like an airplane.

motion time! probably heard of lift force? what you're doing is, as you move through the air, you're displacing the air molecules. think of how it feels to wade through water. the faster you go, the more water pushes back.

now up the magnitude for air since it's less dense. you need to move very fast to displace enough air such that the amount of air pushing back can actually keep you up. but! you also need to deal with that resistance against your motion, too, aka drag.

but in this case, to even keep in constant motion or zero motion, work must be expended to push you up or keep you moving forward, or you eventually slow down and fall like a paper plane

skateboard relies on normal force and friction for its movement. i count staying still as movement, too; it's just movement = 0. you push on the ground with your feet, the ground resists your sideways push, and the wheels can turn, so you move forward.

snowboard relies on something like buoyancy and gravity for its movement. the pressure of the snowboard on an area of snow keeps you up, and you slide downwards because gravity pulls you. friction is still at play but not like skateboarding; the snow is 'slippery' compared to the ground, so you can glide forward

aircraft rely on external forces for any constant motion, even motion = 0. air isn't dense enough to support things in the same way as the ground or snow.

let's get to why it matters for sword flight.

for changing directions horizontally, all three would be similar. you lean (banking) towards the direction you want to turn, relying on the force keeping you level to push you towards the turn.

for climbing or rolling up, similar--you need to push the ground, expend effort to go up a hill on snow, or provide more thrust to exceed gravity's pull to climb in altitude.

diving, rolling downhill are similar. gravity does the work.

the mechanism for slowing down or staying still, however, very different. for sword flight, it's not that you can't; it's that you cannot rely on the same intuition as for terrestrial boarding. you probably need to consciously trade between the qi-pushing you forward to needing to push you upwards, and it's always a balance. you basically need to treat your qi like a reaction control system for spacecraft, which gets into optimal control theory and of course it's not that the human can't intuitively do it. but it is DIFFERENT than skateboarding or snowboarding. you're not moving your weight around to change motion; there's this nebulous qi thing that needs to be controlled alongside the positioning of your weight to do what you want it to do.

so i think the pro-skater (pro-boarder) will have an advantage, but it's not directly equivalent.

now, if qi-powered flight was the equivalent of holding a toy plane making airplane noises to move the thing through the air, moot point. entirely not the same thing at all, they don't have an advantage in qi control. but they do have the advantage of balancing on a thing in motion.

happy winter holidays, sorry not sorry to ambush y'all with physics

#inquiry #Anonymous #on dbd #science shit #look i almost drew diagrams but like i have shit to do #there are a lot of caveats to what i said too but we're going through so much #kinematics+friction+work-energy+pressure+hydrodynamics+fluid mechanics+aerodynamics+control theory #never mind i didn't get into aerothermodynamics for the temperature/density/pressure fluctuations #never mind viscous theory + more complex drag forces #and if they manage to go supersonic that's a WHOLE new can of worms #we don't even know if qi is a field #back to sewing #french seams are a special kind of hell when you need to tailor #and i'm adding gussets so extra extra hellish

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