4 ms·
Water is fairly viscous, and when you try to pull through too fast you completely change regime due to cavitation. In comparison, from my days studying aerodyn
by Arodex 5mo ago
Water is fairly viscous, and when you try to pull through too fast you completely change regime due to cavitation.
In comparison, from my days studying aerodynamics for RC soaring, air has a wider range of "viscosities" (represented by the Reynolds number) depending on the scale of your aeroplane and the speeds you intend to go through the atmosphere. The aerodynamic ideal or what count as useful tricks (winglets, dimples) can be fairly different for a a golf ball compared to a RC airplane compared to a commercial jet compared to a fighter jet...
- naasking 5mo agoWater is also largely incompressible. The fluid dynamics are just too dissimilar to air to carry over simplistic assumptions.
- warumdarum 5mo agoWasnt there something about building abblative vortexes that convert the friction into rotation and are then discarded at the edge of the surface?
- stasomatic 5mo agoAsking as a complete neophyte - how does this reconcile with modern war planes being inherently unstable as far they flight dynamics go, without their enormous thrust capabilities? I’m just curious, I know nothing about the subject, but it seems that the solution we came up with is thrust, baby.
- bombcar 5mo agoUnstable fighters gives them much more maneuverability at the cost of “not returning to straight and level flight” that normal planes have. It’s not directly related to how the wind goes over the wings.
- stasomatic 5mo agoI am curious about humans operating machinery outside of our inherent performance envelopes. Do we have enough runway beyond switching arrow tips from flint to SS?
- xyzzy_plugh 5mo agoA key difference is that war planes occasionally want to be able to rapidly change their trajectories. With sufficient thrust you can fly around in a cube.
- stasomatic 5mo agoWould you a have a link that would show case something like that? It feels like only a T-1000 would be able to make any rapid coherent decisions under such load. Thank you.
- murderfs 5mo agoInstability just means that they don't naturally return to stable flight. Fighter jets benefit from this because when you want to make a maneuver, you're not fighting the plane's natural inclination to stay where it's pointing. You don't need particularly powerful hardware to do this kind of control, quadcopters are an even more obviously inherently unstable example, because any thrust imbalance will immediately make it roll. Quadcopter control loops only need to run at a few hundred hertz to achieve stability.
- soco 5mo agoEnter drone piloting, enter autonomous AI... We are maybe approaching that stage, not necessarily with shiny exoskeletons, but not-human nevertheless.
- stasomatic 5mo agoThey can’t “want “. The pilot may want, but can she, under these loads?
- simne 5mo agoThat's simple - to make quick rotation, you must apply force (torque) and beat inertia - from mathematics could know, the farther from center of mass the more energy will spend to rotate at same speed. So, to rotate faster, you need larger control surfaces. From other side, traditionally, self-stabilize spent at least 1% of energy (on small planes normal up to 10%). What all this mean - with 10 000kg of total weight, your control surface will constantly make 1000kg of force to just fly, but when need to turn, will need significantly more than 1000kg, that's all. Old planes need self-stabilize, because constant corrections was very time consuming, but modern have powerful computers and could provide artificial stabilization - current 1kg computer could provide same stabilization as control surface constantly making 1000kg of force.