Physics Lab B/C

[Epicfail]

Good job! The one at regionals was really easy...
And how come everyone is using two blades? I still vote for more blades...but maybe im an epicfail (like my name)and im wrong.

[wyu1229]

I only get 700 mV on high, and I think the problem is the shape of my blades. I use two cardboard blades that have a somewhat gently round protrusion about two thirds of the way out and that is folded to an angle so that it can capture wind. For your design, do you guys use a triangular shaped propeller (one that is completely straight on its edges and tapers throughout? How wide are your propellers? Do you fold the at an angle so that they can capture wind? It would be nice if there were more pictures for this event on the image gallery so that I can get some better ideas.
Thanks.

[Epicfail]

I only get 700 mV on high, and I think the problem is the shape of my blades. I use two cardboard blades that have a somewhat gently round protrusion about two thirds of the way out and that is folded to an angle so that it can capture wind. For your design, do you guys use a triangular shaped propeller (one that is completely straight on its edges and tapers throughout? How wide are your propellers? Do you fold the at an angle so that they can capture wind? It would be nice if there were more pictures for this event on the image gallery so that I can get some better ideas.
Thanks.

the fan i have that gets 695 on high has 3 cardboard blades 1 inch wide at the bottom and no tilt, i have a 24 blade that also has no tilt thats still untested made of window shades shaped like triangles and an eight blade made of window shade that are shaped like squares with a tilt.

[illusionist]

I only get 700 mV on high, and I think the problem is the shape of my blades. I use two cardboard blades that have a somewhat gently round protrusion about two thirds of the way out and that is folded to an angle so that it can capture wind. For your design, do you guys use a triangular shaped propeller (one that is completely straight on its edges and tapers throughout? How wide are your propellers? Do you fold the at an angle so that they can capture wind? It would be nice if there were more pictures for this event on the image gallery so that I can get some better ideas.
Thanks.

the fan i have that gets 695 on high has 3 cardboard blades 1 inch wide at the bottom and no tilt, i have a 24 blade that also has no tilt thats still untested made of window shades shaped like triangles and an eight blade made of window shade that are shaped like squares with a tilt.

Epicfail- You want to have some tilt(angle) in your blades. otherwise, there is no area for the wind to push on in order to turn your fan. Also, for me, a more curving design seems to work better, instead of triangles and squares...

[wyu1229]

"Epicfail- You want to have some tilt(angle) in your blades. otherwise, there is no area for the wind to push on in order to turn your fan. Also, for me, a more curving design seems to work better, instead of triangles and squares...[/quote]"

Illusionist-- how steep is the curve on your blade? In other words, what is the distance from the farthest point of the curve (i guess you can call it the apex) to the bottom side of the blade? To get tilt, do you fold the curve? And finally, what disc radius do you use? It seems like cutting a CD always works better for me, but I'm not sure what the optimum radius is...

[Epicfail]

Epicfail- You want to have some tilt(angle) in your blades. otherwise, there is no area for the wind to push on in order to turn your fan. Also, for me, a more curving design seems to work better, instead of triangles and squares...

i used window shades, which are made already curved so we didn't have to tiolt them. for the cardboard, we bent it in the middle

[illusionist]

"Epicfail- You want to have some tilt(angle) in your blades. otherwise, there is no area for the wind to push on in order to turn your fan. Also, for me, a more curving design seems to work better, instead of triangles and squares...

"

Illusionist-- how steep is the curve on your blade? In other words, what is the distance from the farthest point of the curve (i guess you can call it the apex) to the bottom side of the blade? To get tilt, do you fold the curve? And finally, what disc radius do you use? It seems like cutting a CD always works better for me, but I'm not sure what the optimum radius is...[/quote]
Experiment with different amounts, because varying shapes will require different amounts. I don't want to go out and tell you exactly how much, just experiment with different amounts. And I agree about the CD, I also use a cut away CD

[blue cobra]

Ok, so I submitted a rules clarification regarding one bladed turbines. I said,

In a one bladed turbine design, should size be judged such that the diameter
of the circle produced by the tip of the blade while spinning on the testing
apparatus must be between the numbers stated?

And their response was,

Yes.

So one bladed turbines should be the radius for the required circle.

[Littleboy]

How do you get the blades to not hit the motor? I have a way but it ads a lot of weight

[blue cobra]

You have them angled away from the motor...

I'm not sure how angling it away from the motor could add any more weight than angling it toward the motor.