Fan Blades: Newsletter Challenge (10/04/05)

He could try counting the shadows from the blades on the floor, I'm not sure if they would be distinct enough, though it did say "bright lighbulbs"

That would put the shadows on the ceiling not on the floor. I imagine turning the fan off or asking the wife if she knows isn't going to be it either.

You're right, missed the "suspended below" part.

That is sample. Just switch "on" another table fan for cooling. Then switch "off" the ceiling fan and you can count the fan blade. Isn't that simple. If you want to count the fan blades with the fan running, wear Rayban sun glass so that the bright light from the bulb is shield off.

get a camera...hi def...and tk a pic. simple or digital camera would work as well... TOO simple!

Blink your eyes really fast. It'll be like watching an olde tyme flick.

Assuming simply switching the fan off is not the answer, how about switching the bright lights on and off at the right frequency to "lock" the blades - the old strobe effect where the rotating m/c appears stationary.

Ceiling fans usually turn slow enough to make this possible - maybe!

I'm not sure, but I'm going to have to go home and try it. Somebody wake me in about two hours...

If the blades are casting shadows on the ceiling, he could check the angle between the shadows. If it is a right angle, then 4 blades; greater than a right angle, 3 blades; and finally if less than a right angle, 5 blades. If the room he is in is rectangular (likely for a home), then it would be easy to judge if the angles formed by the blades' shadows are right or not.

I like this one - it's got a "why didn't I think of that" feel about it!

That should read... "Why did I think of that?" If you cant see the angle of the blades because of their speed, how can you hope to see their shadows?

As written in the 10/11 issue of Specs & Techs from GlobalSpec:

He closes his eyes, waits a little while, then rapidly opens and re-closes his eyes. The bright illumination from the incandescent lamps helps form an after-image in his eyes, clearly showing five fans blades frozen in an instant of time. The process is like pulsing a strobe light, only now the incandescent lamps provide steady illumination and he uses his eye lids as a shutter to capture an instant of the motion.

Doh! How many times have I done just this to look at something rotating or flashing? I may be drummed out of DRC (Dogbert's Ruling Class)for this!!

Stand up on the bed, count the times the fan blades hit your head during one revolution.