2007年3月22日 · Good quality obsidian fractures down to single molecules which can produce a cutting edge 500 times sharper than the sharpest steel scalpel blade ("American Medical News", Nov. 2, 1984:21). On the cellular level an obsidian knife can cut between cells rather than tear the cells as a steel knife will do.

2007年3月12日 · The number of blades is a compromise. When you design a fan like that you want to do work on ALL the air that goes through it. If there are more blades, each blade has to do less work, therefore the forces and stresses in the blade are …

2016年6月20日 · The width and thickness profile changes along the blade to allow for different airspeed and radius. The area of the transducer disc should make no difference to the lift or thrust per unit area. For a boat the minimum diameter of the propeller is proportional to √( power / …

2008年1月3日 · I am just using MathCad as an example, as I don't know others. In college I did use something that did good 3D plots, and solved differential equations and performed integration. I was wondering if there were free or low-cost alternatives to these expensive programs. I just need something...

2024年2月13日 · Sure. Far from a black hole there are normally two changes in causal status. First when an event is no longer in your future lightcone it is no longer definitely in your future, and second when it enters your past lightcone it is definitely in your past.

2024年1月14日 · I'm having a difficult time understanding Euler's turbine equation as it relates to designing a centrifugal air compressor. I need to calculate the impeller size if I know the inlet pressure, outlet pressure, rpm, and mass flow rate. The …

2020年6月19日 · It is said that lift on a wing always acts perpendicular to the relative wind. Why is this so? Is it because we arbitrarily choose to analyze its components with one purposely chosen to be perpendicular or is it a matter of physics that the lift …

2005年1月5日 · Yes, if a plastic shrinks upon heating, it will usually expand when cooled within that same range. This phenomenon is known as negative thermal expansion (NTE), and is seen in other materials besides plastics/polymers.

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2016年6月9日 · In summary, Airwolf is a Mach 1+ helicopter with advanced weapons systems, but its speed is limited by the retreating blade stall and dissymmetry of lift. It is suggested that turning off the rotors could make it more feasible for supersonic flight, but there are still stability and design challenges to overcome.