This is all well and good but there must be a limiting factor in how fast the disk rotates. There must be an max rpm rate. I'm not knowledgable in anyway shape or form. But helecopter designers have faced the problems caused by rotor tips aproaching the spead of sound for years, this has effectivly limited the top speads a helecopter can achieve. Would not the same problems be true of a disk drive. As the outer edge of the disk aproached the sound barrier.