Wind Power B/C

[RestingDoll]

I'm not quite sure I understand why faster blades don't generate more power. The faster the blade, the more revolutions there are that dictate the amount of output voltage; the higher the voltage, the more power generated (v^2/r). Am I missing something here? Or is there another variable attached with maximum voltage?

All other things being equal, a faster blade will generate more power than a slower blade on the exact same setup. The key though is that the resister via something called back-emf actually causes physical resistance to the blade turning. So a blade designed to turn really fast at low resistance might actually end up turned rather slow at larger resistances. The best analogy to this is to consider what would happen if you took a typical airplane propeller and tried to use it underwater as a boat propeller. It wouldn't work very well (assuming you had everything water tight of course and didn't short out the electronics). A boat propeller looks a lot different than an airplane propeller due to the resistance it encounters.

Does higher resistor mean > physical resistance in this case? If so, would it be best to always test on a 25 ohm resistor?

[windu34]

I'm not quite sure I understand why faster blades don't generate more power. The faster the blade, the more revolutions there are that dictate the amount of output voltage; the higher the voltage, the more power generated (v^2/r). Am I missing something here? Or is there another variable attached with maximum voltage?

All other things being equal, a faster blade will generate more power than a slower blade on the exact same setup. The key though is that the resister via something called back-emf actually causes physical resistance to the blade turning. So a blade designed to turn really fast at low resistance might actually end up turned rather slow at larger resistances. The best analogy to this is to consider what would happen if you took a typical airplane propeller and tried to use it underwater as a boat propeller. It wouldn't work very well (assuming you had everything water tight of course and didn't short out the electronics). A boat propeller looks a lot different than an airplane propeller due to the resistance it encounters.

Does higher resistor mean > physical resistance in this case? If so, would it be best to always test on a 25 ohm resistor?

Yes; No - you want a turbine that generates high voltage at both resistances. The optimal design should generate the highest voltage at 5 and 25 ohms

[science R]

What type of material should i make my fins out of for my wind turbine

[chalker]

What type of material should i make my fins out of for my wind turbine

Anything non-metallic. What do you have readily available? As with all Science Olympiad events, a big part of the value is trying different things out inside of just being told exactly what to do. I'm sure if you look around your home you'd find lots of possible things to use to make blades.

[science R]

Would you recomend thin material or thick

[daydreamer0023]

Would you recomend thin material or thick

Depends on the weight of the material. Some teams like to use cereal box or cardstock blades. Others go for balsa blades. Both, I think, have proven to be effective, though it is up to you to experiment with to see which one fits your preferences better.

[sunvenu]

The rules say "The CD must fit on the mount found in a standard CD player.
Modification of the CD is not allowed (except to affix the blades via tape, glue, etc.)." I cannot think of anything else other than tape or glue to fix the blades to CD. Are there any other ways to attach the blades to the CD without modifying the CD. Are plastic screws allowed (that would require holes in CD)?

[SPP SciO]

The rules say "The CD must fit on the mount found in a standard CD player.
Modification of the CD is not allowed (except to affix the blades via tape, glue, etc.)." I cannot think of anything else other than tape or glue to fix the blades to CD. Are there any other ways to attach the blades to the CD without modifying the CD. Are plastic screws allowed (that would require holes in CD)?

The rule is written like that to permit tape or glue, not prohibit it, so I'd suggest sticking with your initial instinct.

It's probably also possible to build a slotted blade that has a friction hold on the cd (akin to a paper clip) but, tape or glue should give you a light and durable hold.

[dhdarren]

The rules say "The CD must fit on the mount found in a standard CD player.
Modification of the CD is not allowed (except to affix the blades via tape, glue, etc.)." I cannot think of anything else other than tape or glue to fix the blades to CD. Are there any other ways to attach the blades to the CD without modifying the CD. Are plastic screws allowed (that would require holes in CD)?

The rule is written like that to permit tape or glue, not prohibit it, so I'd suggest sticking with your initial instinct.

It's probably also possible to build a slotted blade that has a friction hold on the cd (akin to a paper clip) but, tape or glue should give you a light and durable hold.

A slotted blade won't work, at least for this year. If I'm understanding you correct, you're implying that the blade goes on the thin edge of the CD, correct? Since the rules prohibit any part of the blade on the rear side of the CD this year, a slotted blade would be in violation.

[SPP SciO]

The rules say "The CD must fit on the mount found in a standard CD player.
Modification of the CD is not allowed (except to affix the blades via tape, glue, etc.)." I cannot think of anything else other than tape or glue to fix the blades to CD. Are there any other ways to attach the blades to the CD without modifying the CD. Are plastic screws allowed (that would require holes in CD)?

The rule is written like that to permit tape or glue, not prohibit it, so I'd suggest sticking with your initial instinct.

It's probably also possible to build a slotted blade that has a friction hold on the cd (akin to a paper clip) but, tape or glue should give you a light and durable hold.

A slotted blade won't work, at least for this year. If I'm understanding you correct, you're implying that the blade goes on the thin edge of the CD, correct? Since the rules prohibit any part of the blade on the rear side of the CD this year, a slotted blade would be in violation.

Good point - that's rule 3.f. Don't do the slotted blade idea. Glue or tape works fine.