Take a look at the RPM's on my CPU fan

[danball1976]

I find this interesting that it could do that. I'll tell you in a bit how I did that. It whines just like a jet when it does that.

[TheBaron]

lol

[danball1976]

I'd say it was around 125-150db at that speed

[shwaip]

There is no way it is going that fast.

[Cyclonite]

Yeah. That's an error in monitoring.

[danball1976]

Nope, that's no error in monitoring. ;D

[Cyclonite]

It most certainly is. Lol.

Think about this, and someone correct me if I'm doing the math wrong.

Assuming the fan has a diameter of a full 80mm, to get the circumference we take C=(pi)(4cm)^2. That gives us about 50.24cm.

If it were to make 337,500 rounds per minute, a single point would travel a distance of 169,560 meters in one minute. That translates to 105 miles approximately.

If it were traveling at 105 miles per minute, that would be 6300mph, which would destroy the fan before it even reached a tenth of that speed.

Now, someone correct my math if I'm looking at it the wrong way. Even if I am, the possibility of an 80mm fan, or even 120mm fan going that fast is non-existent.

[danball1976]

Well, I used my Dirt Devil vacuum hose, and put it as close as possible to the fan. Besides, it happens to be Vantec's Tip Magnetic Driven fan, which can be reversed very easily like that. I tried it on a regular 80x80 fan, and it doesn't work as well.

[Cyclonite]

Heh. I think it's just a misreading from it going so fast. I don't suspect that it actually travelled as fast as the monitor showed, but I'm sure it travelled damn fast. Just don't do it again, or you may break the fan. ;)

[mmonnin]

Anyone ever seen the video where a guy put CDs onto a Dremel. The CDs shattered, and thats only at a max of 30k RPM. Physics says that speed is impossible. Not like anyone ever believed it.

[danball1976]

I know, I didn't do it any longer than a minute. It whined so loud it hurt my ears. Isn't it true that if you go faster than 100,000RPM, it is spinning faster than the speed of sound?

I don't know, but the bagless Dirt Devil vacuums are pretty powerful.

[Cyclonite]

Wow! A minute? Man. Five seconds of that could kill the fan. Heh. Be careful. ;)

[danball1976]

It most certainly is. Lol.

Think about this, and someone correct me if I'm doing the math wrong.

Assuming the fan has a diameter of a full 80mm, to get the circumference we take C=(pi)(4cm)^2. That gives us about 50.24cm.

If it were to make 337,500 rounds per minute, a single point would travel a distance of 169,560 meters in one minute. That translates to 105 miles approximately.

If it were traveling at 105 miles per minute, that would be 6300mph, which would destroy the fan before it even reached a tenth of that speed.

Now, someone correct my math if I'm looking at it the wrong way. Even if I am, the possibility of an 80mm fan, or even 120mm fan going that fast is non-existent.

Your circumference measurement is highly inaccurate. No way the outer diameter would be 50.24cm (or nearly 1 foot 8 inches).

Correct math would be pi*4cm=12.57cm, there is no squaring unless you want volume.

You would then do 12.57cm times 337,500 = 4,242,375 cm per minute or 42,423.75 meters per minute, which would then be (42423.75m*39in)/12/5280=26.113... miles per minute or 1566.786... miles an hour

Oh, and I also did that to the northbridge fan on the KD7-RAID. I didn't do it as long because I was alot more worried about it exploding because it is so small. (40x40mm)

[Cyclonite]

You're right. I used the wrong equation. It's 2(pi)r. (pi)r^2 is for area, not volume. :) Either way, my original point was that that speed is impossible. ;)

[leishi85]

Your circumference measurement is highly inaccurate. No way the outer diameter would be 50.24cm (or nearly 1 foot 8 inches).

Correct math would be pi*4cm=12.57cm, there is no squaring unless you want volume.

You would then do 12.57cm times 337,500 = 4,242,375 cm per minute or 42,423.75 meters per minute, which would then be (42423.75m*39in)/12/5280=26.113... miles per minute or 1566.786... miles an hour

Oh, and I also did that to the northbridge fan on the KD7-RAID. I didn't do it as long because I was alot more worried about it exploding because it is so small. (40x40mm)

yours is wrong also, it's pi*8cm

[Thrax]

****ing nerds.

[madmat]

I'd say it was around 125-150db at that speed

There's no way it was 150db, you'd be dead. 150db will kill a person pretty much instantaneously by basically liquifying your brain and 125db is loud enough to be physically painful.

You were prolly dealing with 90-100db if that. I've chucked 80mm fan blades into my dremel and spun them up to the full speed the dremel would turn and while noisy, there was no way they were hitting over 80db.

[danball1976]

Ok, then pi*8cm=
25.1327cm*337,500RPM=
8,482,300.1647cm/100cm=
(84,823.0016m*39in)/12in/5280ft=
52.2111 miles per minute*60 minutes=
3,132.6677MPH/720MPH=
4.3509 times the speed of sound.

[madmat]

The speed of sound varies with ambient air temperature, the hotter the air the higher the speed needed to break the barrier. At high altitudes where the air is cold the sound barrier is somewhere around 680mph and when they broke it on the salt flats it was around 700mph due to the air temps on the flats, just thought I'd toss that out there :D

[mmonnin]

You wouldnt be deaf at 150dB. Altho at least here in Ohio 160dB is illegal in cars.

[leishi85]

i would hope so, otherwise, everyone will be going deaf in ohio.

[McBain]

Correct math would be pi*4cm=12.57cm, there is no squaring unless you want volume.




Volume is cubed.....area is squared.

[leishi85]

and there is no volum for a square, as sqaure is a 2d object.

we are such geeks.

[McBain]

yup....we're geeks.

smug ones too. ;D

[Cyclonite]

Haha. Look what I started. Yay geeks!

[Gargoyle]

Maybe 150db explodes your brain, but 160db explodes your car? ;D
We can see where priorities lie in Ohio ;)

[mmonnin]

Hehe its so people dont drive around with that much noise because that WILL make you go deaf. 160dB enclosed inside a CAR. Standing outside of a car doing that much with a car door open will shake your shirt like there is a breeze.

[madmat]

153db in an enclosed car creates over 500psi, you'd stop breathing, your heart would collapse and your central nervous system would turn to jelly in a matter of moments.

Let's review here kids, 120db, threshold of pain, 130db permanent hearing loss within a matter of seconds, 140db, threshold of death, anything above that, faster death.

[csimon]

153db in an enclosed car creates over 500psi, you'd stop breathing, your heart would collapse and your central nervous system would turn to jelly in a matter of moments.
Oh I hate when that happens! ;D

[madmat]

I was doing a little more digging and it seems that at 180db the merest momentary exposure to it is istantaneous deafness...w00t, way to be.

[redchief]

so how many Cubit ft of air was the fan moving at 375000 rpm?

[danball1976]

I dunno, the same amount as the vacuum was pulling I suppose.

[primesuspect]

nerdiest thread EVAR