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Flywheel Hard Disk Drive

Powers itself; doesn't drain laptop battery
 (+6, -1) [vote for, against]

An ordinary computer hard disk drive is built to be fairly lightweight, because the less the disk weighs, the less energy it takes to spin it up to its working speed.

Well, suppose instead the drive was designed for its disk to nearly always be spinning? Then it wouldn't matter so much what the disk weighed.

(1) It is well-known that a lot of energy can be stored in a rapidly spinning disk, usually called a "flywheel". (2) It is also well known that the hard disk of a laptop computer is one of the biggest drains on a laptop battery.

So let us solve the (2) problem by taking advantage of the (1) fact. We PLAN on the disk to store a lot of energy, and we use that to power the disk drive.

Imagine a disk drive that weighed somewhat more than normal. The extra mass is put in the spinning disks of the drive. We could suppose the construction of the disk to contain composite materials, like carbon nanotubes for maximum tensile strength. It has been proved that while extra mass is associated with greater energy storage, even-more energy-storage is associated with higher speeds, so we want the fastest-spinning disks possible to make. That means we want maximum tensile strength, which means carbon nanotubes.

Certain electronics in the drive must be modified, of course. Since the drive is first powered up to run at maximum energy-storing speed, and it slows down as energy is drawn from it, obviously the electronics needs to always know what the current speed of the disk is, so it can save or read data to/from the disk correctly.

There will be some slowest speed at which the user will consider the drive to be saving or fetching data too slow, of course. That's the point where the flywheel/disk must be powered up again, to maximum speed. Ideally we would want this to match the battery-discharge time. That is, if the battery can run the rest of the laptop for 6 hours before it must be recharged, then we want the flywheel to be able to power the disk-drive electronics for those same 6 hours. I'm pretty sure that is technically feasible. And so the charging system would recharge both battery and flywheel at the same time, every time, of course.

In closing I'd like to point out that a flywheel is probably NOT a good idea for powering the rest of the laptop; it will weigh too much. This Idea is merely taking advantage of an already-existing spinning disk, in the laptop, and trying not to go overboard with it.

 — Vernon, Sep 20 2007

64GB SOLID STATE DRIVES http://www.alienwar...ame=press091007.asp
[BJS, Sep 21 2007]

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A geared crank at the back of the computer could be used to provide the initial rpms. [+]
 — zen_tom, Sep 20 2007

What happens if you tilt the computer while the drive is spinning? I know little of hard drives, but I believe that the head is held very close to the platter. The whole thing would surely have to be very rigid to maintain the clearance were the drive suddenly tilted?
 — MaxwellBuchanan, Sep 20 2007

The gyroscopic effect of the flywheel would make carrying the laptop around an amusing experience ...
 — nuclear hobo, Sep 21 2007

 Heh, I was wondering if someone would mention the difficulty of tilting a flywheel. That's why this notion is half-baked, of course!

It could work if the entire drive was fully gimballed, but that wouldn't let it fit inside a laptop.
 — Vernon, Sep 21 2007

But are there any advantages to a rapidly spinning heavy platter over a rapidly spinning lightweight platter?
 — hippo, Sep 21 2007

 Why add extra weight to a laptop?

You should research hybrid and solid state drives.
 — BJS, Sep 21 2007

 [hippo], a more massive spinning disk stores more energy than a less massive disk. We don't want to overdo it, but if we are going to use it, then a more-massive-than-normal disk is appropriate.

The alternatives to hard drives are fine, and don't use so much electricity, but please remember this is the HalfBakery, where I don't have to investigate serious alternatives to an Idea.
 — Vernon, Sep 21 2007

//You should research hybrid and solid state drives// But they won't maintain a constant heading. [+]
 — AbsintheWithoutLeave, Sep 21 2007

I saw "flywheel" and automatically assumed it was [Shapharian] writing. Wonders.
 — elhigh, Sep 21 2007

 At full chat won't the disk be turning too fast for the head to capture data off the disk? I really don't know how much time it takes, but considering just how fast these things can go, and how small the signal loci are to start with, how short a pulse can the head catch before the software disregards it as noise?

Bun for double dutiness.
 — elhigh, Sep 21 2007

What if the user has the computer turned off and unplugged for a few days before wants to use it?
 — BJS, Sep 21 2007

How about a spherical hard drive? Data would be encoded on the surface of a spinning sphere which was suspended by powerful...oh, wait.
 — MaxwellBuchanan, Sep 21 2007

1. A heavier disc would require more force to balance, would require more thrust loading from whatever bearing technology you're imagining, and would react with more gyroscopic loading if the laptop is moved around. 2. In steady-state operation, a lighter disc would still use less energy because of the reduced bearing losses. You also have viscous losses with the air at the surface of the platters. 3. A spinning disc will deform outward. At the data densities encountered in hard drives, it wouldn't take a lot of deformation to cause trouble. (15000 RPM drives ain't cheap, and I can only imagine why.) 4. If your goal is to store energy, remember that the energy has to come from somewhere. The less you intend to store, the less you have to provide ahead of time.
 — kevinthenerd, Feb 22 2012

 Looked at one way, it's 100% efficient, and what other system can say that?

 But why a laptop? Given the problem of tilting a flywheel, this seems better suited to data centers or server farms, as a UPS. They have emergency generators, of course, but there might be an economic advantage in reducing demand on those, or in smoothing out demand so it didn't spike right when the external power went down. (That sort of thing apparently matters a lot to the cost of electricity.)

 Also, the weight of armor to protect against exploding flywheels wouldn't be a problem.

If used for laptops, the difficulty of riding a bike with this device in a backpack might give rise to a new extreme sport.
 — mouseposture, Feb 22 2012

[+] wonderful idea except for the heads won't float under a certain rpm. It would be easier to catch if dropped as well.
 — FlyingToaster, Feb 22 2012

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