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<HEAD><TITLE> For Students </TITLE></HEAD>
<font size="3" face= "arial, sans-serif">
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<hr>
<br>
<h2>
Stuff you want to do<br>
</h2>
Make your hovercraft:<br>
<ul>
<li> <a href="for-students-mfr.html#go-faster.html">go faster!</a>
<li> <a href="for-students-mfr.html#hover-higher">hover higher! </a> (Give your hovercraft a bigger airgap).
<li> <a href="for-students-mfr.html#hovercraft-over-more.html">go over more kinds of terrain and
go over taller obstacles!</a>
<li> <a href="for-students-mfr.html#hovercraft-runtime.html">run for a longer time!</a>
<li> <a href="for-students-mfr.html#hovercraft-payload-increase.html">carry more weight (like heavy R/C equipment!)</a>
<li> <a href="for-students-mfr.html#hovercraft-travel-straight.html">travel in a straight line!</a>
<li> stop spinning around and around!
<li> balance differently. (Change your hovercraft's tilt!)
<li> require fewer batteries because batteries are expensive and take a long time to charge!
<li> controllable with a string!
<li> controllable with radio control!
<li> more roomy! (Create more room for cargo.)
<li> travel in a straight line!
<li> travel in a straight line on an incline or hill!
<li> travel in a straight line when it is windy!
<li> quieter!
</ul>
<br>
<hr>
<hr>
<br>
<br>
<br>
<hr>
<hr>
<br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
<hr>
<a name="go-faster.html"></a>
<h2> Make your hovercraft go faster!</h2>
<ul>
<li>
Add <b> thrust.</b><br><br>
<ul>
<li> Make your hovercraft more powerful.<br>
<a href="for-students-mfr.html#more-powerful-motor.html">
Learn how to make a motor more powerful!</a><br><br>
<li> Add a thrust motor.
<ul>
<li> Add a separate thrust motor held up by a duct stand</br>
<li> Add an airbox that will let you choose between all thrust or half thrust and half lift
</ul><br>
<li> At hovercraft races, the drivers lean forward and back and from side to side throughout the race.
They are trying to change the way their craft is balanced.<br>
<a href="for-students-mfr.html#change-hovercraft-tilt.html">Learn how to change your hovercraft's
balance to make it go faster!</a><br> <br>
<li> Use other sources of thrust (a different propeller, a different motor and propeller, a sail, a model rocket, etc).
</ul>
<br>
<li>A hovercraft goes fast by staying above the ground. If it touches the ground, the hovercraft experiences <b> friction</b>, which slows it down. <br>
<a href="for-students-mfr.html#less-hovercraft-friction.html">Find out how to make your hovercraft have less friction!</a>
<br><br>
<li> The lighter your hovercraft is, the faster it will get to its top speed. (Teachers, here is a chance to teach about <b> innertia</b>.)<br>
<a href="for-students-mfr.html#less-hovercraft-weight.html">Make your hovercraft lighter!</a>
<br><br>
<li> At hovercraft races, the drivers lean forward and back and from side to side throughout the race. They are trying to change the way their craft is balanced.<br>
<a href="for-students-mfr.html#change-hovercraft-tilt.html">Learn how to change your hovercraft's balance to make it go faster!</a><br>
<br><br>
</ul>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br>
<hr>
<a name="hover-higher"></a>
<h2> Make your hovercraft hover higher!</h2>
<ul>
<li> <a href="for-students-mfr.html#less-hovercraft-weight.html">make your hovercraft lighter!</a>
<br><br>
<li> Add lift!
<ul>
<li> Make your hovercraft's lift motor more powerful.<br>
<a href="for-students-mfr.html#more-powerful-motor.html">
Learn how to a motor more powerful!</a><br><br>
<li> Add lift motor.
<ul>
<li> Add a separate lift motor </br>
<li> Add an airbox that will let you use half the motor's power
for lift and half for thurst (or all thrust and no lift).
</ul><br>
<li> <a href="http://www.gohover.com/wig.html" >Add wings </a><br>
(You might even try other kinds of dynamic lift, like helicopter rotors)
<li> Try a helium balloon?
<li> Try a peripheral jet system -- a skirt made out of high pressure air. <br>
(Sorry, the page on how to build a peripheral jet system is still in development.)<br>
</ul>
</ul>
<br><br>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br><br><hr><br>
<a name="more-thrust-hovercraft.html"</a>
<h2> Add Thrust</h2>
<ul>
<li> Make your hovercraft's thrust motor more powerful.<br>
<a href="for-students-mfr.html#more-powerful-motor.html">
Learn how to make a motor more powerful!</a><br><br>
<li> Add a thrust motor.
<ul>
<li> Add a separate thrust motor held up by a duct stand</br>
<li> Add an airbox that will let you choose between all thrust or half thrust and half lift
</ul><br>
<li> At hovercraft races, the drivers lean forward and back and from side to side throughout the race.
They are trying to change the way their craft is balanced.<br>
<a href="for-students-mfr.html#change-hovercraft-tilt.html">Learn how to change your hovercraft's
balance to make it go faster!</a><br>
</ul>
<br><br>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br><br><hr><br>
<a name="more-powerful-motor.html"</a>
<h2> Make a motor more powerful</h2>
<ul>
<li> Make the propeller tip clearance smaller. <br>The propeller works best when it spins as close as possible to the walls of the duct. The walls of the duct slope inward, so you can make the propeller come closer to the walls of the duct by pulling the propeller along the motor shaft. As you pull the propeller, it will get just a little bit further from the motor, and the distance between the duct's wall and the propeller will be just a little bit smaller. (Teachers, here is a chance to teach about the aerodynamics of a duct.)
<br><br>
<li> Add a battery cell
<br><br>
<li> If you have two motors connected to two or more motors in a serial circuit,
hook up the motors in a parallel circuit instead. (This will increase the voltage available to each motor.) (Teachers: here is an opportunity to teach about circuits)
<li> Use a different kind of battery
</ul>
<a name="more-powerful-hovercraft.html"></a>
<h2> Make your hovercraft more powerful!</h2>
<ul>
<li> Your hovercraft is powered by motors. Want to make your hovercraft more powerful?<br>
<a href="for-students-mfr.html#add-hovercraft-motor.html">Add another motor!</a>
<br>
<ul>
<li>Advantages: this will add a lot of extra power
<li>Disadvantages: this makes the craft heavier, and require more electricity from somewhere.
</ul>
<br>
<li> The motors are powered by electricity. The electricity comes from batteries. If you add more batteries, you'll produce more electricity. If you add more batteries to the ones that are already in a circuit, you'll increase the voltage. Increasing the voltage will make your motor spin faster <b>(why?)</b> and in turn will make your propeller spin faster. This needs to get cleaned up. <br>
<a href="for-students-mfr.html#add-more-batteries">Add more batteries!</a>
<ul>
<li>Advantages: This will also add a lot of power, without adding as much weight.
<li>Disadvantages: Batteries still have some weight, and they are expensive and take time to charge.
</ul>
<br>
<li> If your hovercraft has more than one motor, it matters how your batteries are hooked up to the motors.
Different kinds of circuits supply different levels of power to the motors. <br>
<a href="for-students-mfr.html#try-different-circuit.html">Try a different kind of circuit.</a>
<br>
<ul>
<li>Advantages: Changing the circuit doesn't add weight.
<li>Disadvantages: Changing the circuit doesn't really add power, it just changes how the power is
distributed.
</ul><br>
<li> Different kinds of batteries provide different amounts of power. <br>
<a href="for-students-mfr.html#different-batteries.html">Try a different kind of battery.</a>
<br><br>
<li> Batteries aren't the only power source for your hovercraft. <br>
<a href="for-students-mfr.html#try-different-power-source.html">Try a different power source.</a>
</ul>
<br>
----------Non GH methods (at least currently)<br>
<ul>
<li> try a different motor
<li> try a different propeller
<ul>
<li> try a larger diameter propeller
<li> try a different pitch
</ul>
<li> adjust pitch on propeller
</ul>
<br>
<br>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br>
<hr>
<br>
<a name="learn-about-friction-and-hovercraft-weight.html"></a>
<h3> Learning about Friction, part 2</h3>
We've already seen that friction occurs when two things slide past each other. But that's not the whole story.<br><br>
Try running a GH-1 single motor craft with the trapdoor open -- watch it hover away!<br>
<br>
Close the trapdoor, so that the craft is in "airboat mode". If you didn't know better, you might expect it to run faster, since the craft has twice as much thrust, but, of course, it won't move at all, due to friction.<br>
<br>
Ok, now hook up the batteries to long wires. Hold the batteries in your hand, and let the wires hang down to power the craft remotely. Now repeat the above exercise. <br>
<br>
Of course, with the trapdoor open, in hovercraft mode, the craft will really zip around, with no payload to slow it down.<br>
<br>
But here is the interesting part: close the trapdoor, so we are back in airboat mode, and try running the craft. Even in airboat mode, when the craft has no batteries to carry around, the craft will run surprisingly fast on a smooth floor!<br>
<br>
This demonstrates that friction is dependent on weight as well as on smoothness.<br>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br>
<hr>
<a name="less-hovercraft-friction.html"></a>
<h2>Make your hovercraft have less friction</h2>
<ul>
<li> If the rear of the craft is dragging along the ground,<br>
<a href="for-students-mfr.html#change-hovercraft-tilt.html">Change your hovercraft's balance!</a><br><br>
<li> If your craft is alreay balanced, maybe it simply isn't high enough off the ground to avoid all the obstacles.<br> In that case, you need to <a href="for-students-mfr.html#hover-higher">hover higher! </a> <br><br>
<li> Look at the skirt while the hovercraft is hovering. It is probably always touching the ground at one place or another. Everytime it touches, there is a little more friction (but not a lot more! Can you explain why?). To reduce friction a bit more, if your hovercraft has a detachable skirt, try removing it.<br><br>
<li> Try this <a href="for-students-mfr.html#learn-about-friction-and-hovercraft-weight.html">fun activity </a>to see that friction depends on weight and then<br>
<a href="for-students-mfr.html#less-hovercraft-weight.html">make your hovercraft lighter!</a><br><br>
<li> use a larger hull (ie use a larger tray) <br>
James, is this true? Do larger hovercraft have less friction, all other things being equal?
</ul>
<br>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br>
<hr>
<a name="less-hovercraft-weight.html"></a>
<h2> Make your hovercraft lighter!</h2>
<ul>
<li> Use fewer onboard batteries
<ul>
<li> use NO onboard batteries by using handheld batteries with long wires<br>
disadvantage: long wires aren't as much fun<br>
disadvantage: long wires have more <b>electrical resistance</b><br>
<li> use fewer onboard batteries per motor
<li> run multiple motors with one set of batteries
<ul>
<li> use a parallel circuit
<li> use a serial circuit
</ul>
</ul>
<li> Use a smaller hull (ie use a smaller foam tray)
<li> Use different (lighter weight) batteries
<br> <u> Use Smaller batteries of the same chemistry.</u>
<br> <u> Use a different chemistry batteries </u> which weighs less.
<li> Remove unneeded mass
<br> For example, the cover of the battery holder is heavy and can be replaced with a rubberband, foam, and velcro.
<br>(this might violate the "no irreversible changes" rule)
</ul>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br>
<hr>
<a name="change-hovercraft-tilt.html"></a>
<h2> Change the way your hovercraft tilts</h2>
<h3> What happens when your hovercraft tilts:</h3>
<ul>
<li> When the hovercraft tilts forward, it has the following effects:<br>
- it decreases friction if tail is dragging.<br>
- it increases the amount of air escaping out rear, generating a small amount of thrust.<br>
<li> Tilting backward has the following effect:
<li> Tilting to the left or right has the following effect:
</ul>
<h3> How to make your hovercraft tilt:</h3>
<ul>
<li> Move center of mass (batteries) in any direction to tilt the hovercraft in that direction(see "lessen friction" method
below)
<li> Turn on the thrust (or increase the thrust) and your hovercraft will tilt forward. <b>(Why?)</b>
<br> Tell story of flying saucer with thrust motor.
<li> If there is a separate lift duct is at the front of the craft, as in the GH-2,
increase the lift (or decrease the thurst) and your hovercraft will tilt backward.
<li> Use elevator for tilting forward or backward.
</ul>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br>
<hr>
<br>
<a name="add-hovercraft-motor.html"></a>
<h2> Add another motor!</h2>
<ul>
<li> Add a thrust motor
<li> Add a lift motor
<li> Add a motor to an airbox (thrust or thrust & lift)
</ul>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br>
<br>
<hr>
<br>
<a name="hovercraft-over-more.html"></a>
<h2> Hover over more kinds of terrain & go over taller obstacles</h2>
<ul>
<li> <a href="for-students-mfr.html#hover-higher">Hover higher! </a> (Give your hovercraft a bigger airgap).
<li> <a href="for-students-mfr.html#less-hovercraft-friction.html">Find out how to make your hovercraft have less friction!</a>
<li> Use a skirt...
<li> or don't use a skirt!
<li> increase height of skirt?
<li> <a href="for-students-mfr.html#change-hovercraft-tilt.html">Have the hovercraft tilt backward</a> so that the front doesn't bump into obstacles.
<li> Use a slanted front (like the wave jumper or wave hopper)
</ul>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br>
<br>
<hr>
<br>
<a name="hovercraft-travel-straight.html"></a>
<h2> Make your hovercraft travel straight</h2>
<ul>
<li> try adjusting the center of mass left and right<br>
If the hovercraft leans away from one side, air will escape from that side and propel the craft the other way.<br>
<li> try adjusting the center of mass forward and rearward<br>
If the nose digs in, the craft will tend to turn to the left or the right<br>
if the tail drags, the craft may also turn to the left or right.<br>
<br>
<li> reduce spin<br>
<li> straighten airflow from thrust
<li> straighten airflow from lift
</ul>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br>
<br>
<hr>
<br>
<a name="hovercraft-runtime.html"></a>
<h2> Make your hovercraft run for a longer time </h2>
<ul>
<li> Use batteries with more capacity
<ul>
<li> Try using a larger size battery <br>
Use AA's instead of AAA's<br>
(battery size determines capacity, not voltage, not "strength", etc)<br>
<br>
<li> Try using a different kind of battery (different battery chemistry)<br>
<ul>
<li>NiMH and NiCds are better than disposable batteries.<br>
<li>NiMH lasts twice as long as NiCd<br>
<li>Li-Poly and Li last even longer, but come in inconvenient voltages<br>
</ul> <br>
</ul>
<li> Use less power
<ul>
<li> try using fewer batteries per motor
<li> try using fewer motors per battery
<li> try using a different kind of circuit
</ul>
</ul>
<br><a href="javascript:history.back()">Go back to where you came from.</a><br>
<br>
<hr>
<br>
<a name="hovercraft-payload-increase.html"></a>
<h2> Make your hovercraft carry more weight </h2>
<ul>
<li> Use a skirt
<li> Make your hovercraft hull larger (use a larger foam tray or other large piece of foam).
<br>A larger hovercraft can carry more weight (up to a point). <b> (Why?)</b>
<li> <a href="for-students-mfr.html#less-hovercraft-weight.html">Make other parts of your hovercraft lighter.</a><br>
<li><a href="for-students-mfr.html#more-powerful-hovercraft.html">Make your hovercraft more powerful!</a><br><br>
</ul>