Hovercraft

[arielcay]

I am trying to help my daughter build a hovercraft. I have never done this before. Her science project is due by December 10th. My question is this, If we build this thing and it acutally flies we need to do some friction experiments. I need ideas besides just sit on it. Can anyone help me? I think she needs to do some kind of display board too. (Maybe something like friction controller? Which to me sounds impossible...LOL) One more thing. If anyone has ever built one.. WHAT is the best type of air blower to use?

[deleted-71588]

Sounds like you picked something interesting to work with.

If we build this thing and it acutally flies

By definition, a hover craft will NOT fly. The basic hover craft design is to pump air into a chamber bounded by the surface you want to hover over, a skirt, and the hover craft platform. The idea is to be able to pump air into this chamber fast enough so that even though air is leaking out between the bottom edge of the skirt and the surface, enough pressure builds up in this chamber to exert a force equal to the weight of the hover craft so that it lifts up off the surface. As the skirt lifts off the surface, air escapes more rapidly and the pressure decreases so the lifting force decreases and the platform comes down. If you manage to balance things well, you can get to a stable point of floating slightly above the surface.

I need ideas besides just sit on it.

You need to scale back your expectations on what you can afford to achieve in a few weeks. It typically takes something like a small jet engine to develop enough power to move enough air to lift the fuel, the engine, the air turbine/compressor, the weight of a structure that can support these and a small load.

My recommendation is to think small. If you use a shop vac or leaf blower sitting on a table with a flexible hose attached to a small very light weight experimental hover craft on the floor, you don't have to lift the weight of your air source, only some portion of the weight of the supply hose in addition to the test hover craft. This simplification will make it much easier to demonstrate the principles with equipment that is safe to experiment with. Unfortunately, having this hose attached will limit any propulsion type experiments.

In order to make this into a science fair project, you need a hypothesis and then figure out how to test your hypothesis scientifically. Please refer to "The scientific method" and "Your question" on https://www.sciencebuddies.org/science- ... ndex.shtml for some guidance.

we need to do some friction experiments.

I'm not sure what you mean by friction as it applies to hover craft. There are friction like properties involved with aerodynamics in the fan, air hose, and with air escaping under the skirt but I don't recognize any classical "friction" properties involved in a hover craft design.

Typical measurements you might want to take probably involve the velocity of air flow so you are going to have to research and invest in something to measure air flow and figure out how to adapt it to whatever setup you come up with to get the data needed to evaluate your hypothesis.

[deleted-71709]

Welcome to Science Buddies. I hope I can be some help to you.

Working on a hover craft with your child would qualify you to become a "Geek Dad". This is a special person in a young person's life. The phrase comes from a feature that is run occasionally on the PBS series "Wired Science". I saw an episode last season that accomplished just what you want to do. Here's a link to the Wired Science web site that tells you one way to build a hover craft. http://www.pbs.org/kcet/wiredscience/st ... d_ufo.html

In this case, the craft is large enough to sit on, and is powered by a leaf blower. If you "Google" "how to build a hover craft", you'll be barraged with ideas. Try this one: http://www.break.com/index/how-to-build ... craft.html, or this one, http://groups.physics.umn.edu/pforce/hovercraft.html.

You're correct about the need to collect some kind of data to make a good science project. I would suggest measuring the force it takes to glide the craft over a surface with different amounts of weight on it. You will find you will not be able to move any heavy weight effectively until you get down to the "take-off" point of the craft. And this will vary, depending on the surface. For instance, you should be able to lift a greater weight on a smooth surface, than on one that is highly textured, such as a carpet.

Whatever you come up with, have a great time working with your child.

I hope this helps.

[arielcay]

According to my daughters teacher, 6th Grade, SHE was not impressed with my daughters science project choice. NEXT when my daughter turned in her project of building one, she (teacher) said, "WELL I ALREADY KNOW IT CAN FLY, YOU HAVE TO COME UP WITH A BETTER QUESTION LIKE< HOW DOES FRICTION EFFECT THE CRAFT (weight). I told her teacher, "Part of building it according to the directions says .."THEN sit on it." But we need (again If it will fly LOL that in itself ought to be intersting) We must experiment with it. I thought maybe putting weights in different places on the craft as it floats AND, differet size weights. MAYBE even a FAN for resistances. AND Mommy is only helping with research, You are right about GEEK DADDY, that is his department to help her build it and make it fly. HER father is a smart ingeniose man. IF it is possible, he will make it fly. I will let you know by sending pictures if you guys are interested. They may help you help others who may choose to build one. Also,This project when complete will be entered in to FL state science fair. First prize is $500. Great to add to the college fund. BUT I will also make sure to QUOTE all the helpers in the journal. That includes you guys.(smile) THIS was my daughters first HYPOTHISIS which got rejected, for obvious reasons. MY HYPOTHISIS IS: I THINK THE HEAVIER THE OBJECT IS< THE FASTER THE CRAFT WILL MOVE< BUT THE SLOWER IT WILL ACCELLERATE. Don't laugh now.... she has no idea what she chose for a project I can see. She just wants to sit on it. lol GREAT FAMILY PROJECT!!!! Quality Family time.

[arielcay]

ONE MORE THING.. We are not to worried About the cost..... We want it to fly. (smile) And no I can't afford a Jet engine, But I bet that would make it fly.... Thank you so much for the links and advice... I 'll keep you posted ... The hard part is pleaseing my daughters teacher for class project, we get past that, then the state science fair will be a breeze. I hope.

[deleted-71417]

Hi,

You might find this hovercraft discussion thread from last year useful:

https://www.sciencebuddies.org/mentorin ... =29&t=3024

Best regards,

Barrett Tomlinson

[arielcay]

My daughter and her father were successful at making a hover craft. They used 1/2 in ply wood and a battery operated leaf blower. The web site we used was :

http://amasci.com/amateur/hovercft.html

The shaft was modified to its shortest length. We have have come up with a hypothesis. I am wondering if this is acceptable for a 6th grade teacher, or do we need to change it. "THE HOVER CRAFT LIFTS OFF THE SURFACE THE SAME AMOUNT REGUARDLESS OF HOW MUCH WEIGHT IS ON IT". We figured we can put different weights on a craft and hold a ruler to the floor/surface of ground and measure how high it lifts the weights. Would this be acceptable?

By they way...YOU guys are right ...I does not FLY...IT FLOATS.....IT REALLY DOES WORK.(smile)

[deleted-2131]

arielcay,

My apologies for the delayed response to your post. I think that the hypothesis you have stated is a good one - it is testable, which is a major criterion that hypotheses need to meet. It sounds like you had a very successful time constructing and testing the hovercraft; let us know if we can be of further help.

[arielcay]

This project turned out to be an "A" project. Thank you for the help.