American V8's - Curious
American V8's - Curious
(OP)
The mechanical drive fans on american v8's are never symetrical. They have equally spaced blades except for one or two locations that are oddly spaced. Whats up with that?
Just a Friday afternoon off in the clouds kinda question.
Any suggestions?
I have come up with;
balancing for other items (viscous clutch)
maybe the designer had really thick glasses?
fluid flow dynamics?? (not sure what might require this)
Just a Friday afternoon off in the clouds kinda question.
Any suggestions?
I have come up with;
balancing for other items (viscous clutch)
maybe the designer had really thick glasses?
fluid flow dynamics?? (not sure what might require this)





RE: American V8's - Curious
However, is it possible that they make a standard fan and, depending on the application or power available to drive it, they remove some of the blades to reduce load?
Or perhaps they got it all wrong in the first place and "overloaded" the fluid drives. To save throwing the 20,000,000 fans they had already made they just reduced the blade numbers??????
RE: American V8's - Curious
Rod
RE: American V8's - Curious
RE: American V8's - Curious
RE: American V8's - Curious
Typical steel fans have an odd number of blades, and they're all unevenly spaced, some a little, some a lot, so they won't form constructive interference with each other or with nearby stationary objects, e.g. radiator fins.
Contrast them with a mechanical siren, comprising evenly spaced vanes of a frustrated centrifugal air pump, interacting closely with evenly spaced stationary bars and slots.
Mike Halloran
Pembroke Pines, FL, USA
RE: American V8's - Curious
If you stagger the blades then the result is the same overall sound level, but the tonal component is not as high.
They do the same with tread patterns on tires, and possibly on alternator cooling fans.
Bear in mind they still need to balance, so you only have a limited choice.
Cheers
Greg Locock
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RE: American V8's - Curious
might work, otherwise look in the Gallery at
http://www.geocities.com/greglocock
it's the top link. This is the (predicted) noise spectrum of a five bladed fan.
red is the baseline, blue is with 4 of the blades staggered by 10 degrees, although I didn't check the balance.
The strength of the fifth order tonal drops a bit , and oddly the tenth order drops a lot. The penalty is that you get all the other orders springing up. The improvement is about 4 dB at the peak tone, but I didn't optimise this. Incidentally, the balancing vector is fun - it's a pentagon with equal length sides, so it is symmetrical. A six bladed fan gives you many more possibilities.
Cheers
Greg Locock
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RE: American V8's - Curious
Regards,
Cory
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RE: American V8's - Curious
non standard spacings for helicopters to reduce
the noise level. Do not know if they still do
this or not.
RE: American V8's - Curious
Putting it another way, it reduces the sickness of "knuckle-busted-itis". Whether this was a planned advantage for the mechanic or an inantvertent one, I am not sure, but I have been thankful for it a few times.
BK
RE: American V8's - Curious
Cheers
Greg Locock
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RE: American V8's - Curious
Mike Halloran
Pembroke Pines, FL, USA
RE: American V8's - Curious
RE: American V8's - Curious
-The future's so bright I gotta wear shades!
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RE: American V8's - Curious
Or you could add a counterweight, but that's ugly.
Incidentally I think modern automotive cooling fans are balanced individually, but that may just be prototype ones.
Cheers
Greg Locock
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RE: American V8's - Curious
RE: American V8's - Curious
I know for a fact that this is done on alternator cooling fans - I work in a facility that makes alternators. Not only is the spacing uneven, the blade sizes and angles are different as well.
RE: American V8's - Curious
RE: American V8's - Curious
RE: American V8's - Curious