Science Buddies: "Ask an Expert"

For a science project I am proposing to exhibit the role of dimples in golf balls for sustaining longer flight by reducing drag. One approach is to shoot dimpled and undimpled balls from a pressurized air cannon and measure the distance differences. I am doing this. Another approach is to build this, https://www.sciencebuddies.org/science- ... ion1.shtml, and try to measure the different resistances offered by dimpled and undimpled balls. Do you think this wind tunnel is appropriate for measuring the drag differences between dimpled and undimpled golf balls?

Thanks!
LimaDelta

Hello,

Thank you for your question. I am the designer of the Science Buddies wind tunnel that you linked in your question.

The tunnel was designed to test airfoil models, and so I do not believe it would be appropriate to use it for testing golf balls. However, if you were to modify the design a bit, you may be able to get what you need out of it. Unfortunately, I cannot offer expert advice about testing golf balls in a wind tunnel.

I suggest that you re-post this question in the Physical Sciences forum for grades 9-12. There are many more experts there that can help you adjust the design of this tunnel, or come up with other ideas, in order to test the golf balls. The link to the forum you want is here:
https://www.sciencebuddies.org/science- ... m.php?f=29

Good luck on your project!

Why don't you think it would work? Shouldn't the design be able to measure differences in drag of any object?

I do not think it will work because the mounting mechanism is not designed for a ball. The design uses two sensors and some rods to mount an airfoil model, but it's not designed to mount a golf ball. The wind tunnel itself will work just fine, it's just the mounting design that needs some adjusting.

Unfortunately, I do not have any expert advice about how to mount a golf ball, so I suggest that you take your question to the Physical Sciences board that I linked in my last post. There, you'll find other experts who may have more ideas.

Good luck!

Hi
I've built my own wind tunnel for the same purposes, to measure the drag on a golf ball.
The problem is I don't know how to measure this and can't seem to find out.
If you can offer any help whatsoever it would be greatly appreciated
Thanks, Tommy

Hello Tommy,

Measuring drag is difficult, because you have to find a way to attach a force sensor to the test subject parallel to the wind stream, without disturbing the wind stream or pushing too much on the specimen (interfering with the drag) in the first place!

I'm asking a colleague of mine for ideas for you. In the meantime, I suggest that you do some internet searches to see what you can find. Also, you could try tying a string around the ball, running it back upstream (toward the fan), and attaching it to a force sensor, so that it would measure drag as a pulling force. You'd need the sensor to be out of the way of the flow, so perhaps you could use a pulley to run the string up and out of the wind stream before it attaches to a force sensor. You'd have to have a slim pulley so that it wouldn't mess up your flow.

I'll let you know if my friend has any ideas. Good luck on your research!