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Hovercraft Help
Moderators: kgudger, bfinio, MadelineB, Moderators
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anin1009
- Posts: 1
- Joined: Sun Nov 27, 2011 12:49 am
- Occupation: Student
- Project Question: What's the minimum motor power (in watts) of the leaf blower for a hovercraft (from: http://www.sciencebuddies.org/science-f ... 5&from=TSW) to carry a person with at least 65 kg weight? Thanks!
- Project Due Date: Some time in February (No exact date yet)
- Project Status: I am just starting
Hovercraft Help
I'm building a hovercraft i found on this site. (https://www.sciencebuddies.org/science- ... 5&from=TSW) I just wanted to ask what's the minimum motor power (in watts) of the leaf blower for the hovercraft to carry a person at least 65kg (at least that's how much i think my teacher weighs) in weight. Thanks!
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deleted-71882
- Former Expert
- Posts: 338
- Joined: Sun Jul 10, 2011 5:48 pm
- Occupation: retired physicist
- Project Question: n/a
- Project Due Date: n/a
- Project Status: Not applicable
Re: Hovercraft Help
Hello anin1009,
You pose a very good question, but I think it's hard to answer. Here are the issues.
A leaf blower is designed to push a large volume of air. Your hovercraft will lift off when the pressure under it becomes high enough. Before it lifts, very little air should escape from under the disk. The main thing you need to know is, "Can my leaf blower generate enough pressure?"
Just how much pressure your blower can generate depends on a lot of things other than just its power rating. Among these things are:
So you will need a pressure of 637 Newtons / 1.18 sq. m = 540 Newtons / sq. m. Converting this pressure to English units of pounds / sq. in. gives approx. 0.078 lbs/sq. in.
How can you measure the capacity of your blower? A very simple test would be to place your hand over the output tube and estimate how much force you feel. Clearly this method is very crude, but may be sufficient.
If your blower has the common output diameter of 2-1/2", the force on your hand needs to be 0.078 lbs/ sq. in times 4.9 sq. in. = 0.38 lb.
Place a 1 lb. weight in your hand (say a 1 lb. box of candy) and become familiar with how it feels, then put your hand under the blower. My guess is that you will feel a force much greater than 0.38 lb., so you can guess that it is capable of lifting your teacher.
The volume of air that the blower can push will determine how far off the ground you can lift.
Good luck, WW
You pose a very good question, but I think it's hard to answer. Here are the issues.
A leaf blower is designed to push a large volume of air. Your hovercraft will lift off when the pressure under it becomes high enough. Before it lifts, very little air should escape from under the disk. The main thing you need to know is, "Can my leaf blower generate enough pressure?"
Just how much pressure your blower can generate depends on a lot of things other than just its power rating. Among these things are:
- How efficient is the motor?
How well does the fan blade function when the airflow is restricted?
So you will need a pressure of 637 Newtons / 1.18 sq. m = 540 Newtons / sq. m. Converting this pressure to English units of pounds / sq. in. gives approx. 0.078 lbs/sq. in.
How can you measure the capacity of your blower? A very simple test would be to place your hand over the output tube and estimate how much force you feel. Clearly this method is very crude, but may be sufficient.
If your blower has the common output diameter of 2-1/2", the force on your hand needs to be 0.078 lbs/ sq. in times 4.9 sq. in. = 0.38 lb.
Place a 1 lb. weight in your hand (say a 1 lb. box of candy) and become familiar with how it feels, then put your hand under the blower. My guess is that you will feel a force much greater than 0.38 lb., so you can guess that it is capable of lifting your teacher.
The volume of air that the blower can push will determine how far off the ground you can lift.
Good luck, WW