Step 2: Back to the pressure...

Water rockets use air pressure to throw the water out of the rocket, but it doesn't have to be air. Alka-Seltzer (or 'A-S') rockets use gas pressure to throw water out the back, like the water-rocket, but you don't need so much equipment, so much effort, or even so much preparation. The easiest way to find out what we're talking about is to try it. Time for another experiment.

Take an 'Alka-Seltzer' tablet (or any other indigestion remedy with the word 'effervescent' on the packet) and drop it in water. See the fizz? That is carbon dioxide gas (CO2). The gas is produced by a chemical reaction between the solid ingredients of the tablet. Notice how the froth is a lot bigger than the original tablet? If we can trap this large volume of gas, we can create enough pressure to power a rocket.

Time to Build Another Rocket.

As with any experiment involving chemicals or fast-moving parts, safety must be observed. A-S rockets can be fast, so wear safety goggles, which also serve to prevent chemicals being splashed in the eyes. If you know you have an adverse reaction to aspirin (an ingredient of Alka-Seltzer), you should take extra care, or even avoid doing this experiment all together.

These rockets need some, ahem, highly technical equipment:

An Alka-seltzer tablet
A 35mm film canister
Some water

That's it. Really. The rocket is finished. There's nothing else to do except...

Launching the A-S Rocket

A-S rockets are best launched outdoors, as they can go higher than a typical ceiling, but if you have access to a large room with an easily-dried floor (school science lab, church hall, warehouse, etc) then go for it.

Launching an A-S rocket takes quick, nimble fingers. Put a small amount of water in the film canister (about a teaspoon full is a good start). Snap the tablet into four quarters, put on your goggles and get ready for the speedy bit:

Drop-the-tablet-in-the-water, put-the-lid-on-quickly, stand-the-canister-upside-down-on-a-surface-that-doesn't-mind-getting-wet and-stand-back.

The ingredients on the A-S tablet dissolve in the water, and the fizzing starts. CO2 is being generated and the pressure is rising inside the canister. Don't lean over it, because very soon the pressure will be great enough to throw the lid off and the water out backwards, sending the body of the canister flying upwards. There will also be a certain amount of splashing, so don't stand too close!

Alka-Seltzer Rocket Recovery

Now that it's empty, the canister is very light, so it doesn't need a parachute, and won't do any damage on the way down. Watch carefully as it falls, just in case a gust of wind carries it away.


> A-S rockets can become the heart of a lot of 'proper' Science:

> What are the ideal quantities of water and tablet to add?

> Will other combinations of chemicals yield the same effect (baking soda and vinegar?)

> Can streamlining improve the tumbling flight of the canister?

> Will other containers act as rockets as well? What about a fizzy pop bottle with a cork in?
What do they call Boy Scout of America across the pond or is it just Boy Scouts or just Scouts
Here, in the birth-place of Scouting, we just call it "Scouting" (since girls are allowed to join as well).
here in the dirty usa girls arent allowed to play with the boys at all. they formed thier own gruop starting with brownies ofall the food gruops to go with!!
<p>BSA actualy started a group called Venture scouting the is CO-ed </p><p><a href="http://www.scouting.org/scoutsource/Venturing.aspx" rel="nofollow">http://www.scouting.org/scoutsource/Venturing.aspx</a></p><p>link provided in case you have or know girls that are interested.</p>
We have those as well: <br> <br>Rainbows &gt; Brownies &gt; Guides
A bit advanced one is trying with a KNO3 fertiliser(or stump clearer) and mixing it with table sugar. The ratio is 35:65. But Beware! a small problem is enough to burn a paddy field.
Hey Kiteman, I'm having a bit of a problem with the match stick rocket, and was wondering if you could help? I've tried it twice now, and both times I've ended up with semi-flaming (technically it was the match head that was flaming) foil. I'm wondering if this means I need to use more foil, or is it something else? <br> <br>Thanks for your time. <br>-ElvenChild
My first thought is to recommend more foil.<br><br>Make sure the rocket is capable of actually launching, and isn't too tight on the match intended to stay behind.
My only match rocket experience is using a meter long lab glass tube fire sealed at one end<br> held secure at an appropriate up angle to allow a stick match to slide head down and ignite&nbsp;<br> at the molten glass end.<br> <br> The expanding gas makes an excellent simply&nbsp; re-loadable mortar able to easily launch sticks<br> as far as10 meters away.<br> <br> A
A matchstick mortar...? <br> <br>Ohhh...
Ahh Burt Rutan. He is my role model. <br>(Along with Mr. Steve; )
Baking Soda and Vinegar is a lot more fun and costs less:<br> <br> <a href="http://www.instructables.com/id/Film-Container-CO2-Rocket./" rel="nofollow">http://www.instructables.com/id/Film-Container-CO2-Rocket./</a>
This is a lot less messy, though, and (when you've got a class of thirty 11 year-olds doing this) it makes the risk-assessment paperwork easier to have water splashing instead of acidic vinegar. <br> <br>Oh, and isn't it about time you posted another project? <strong><sub>;-)</sub></strong>
you should put the football adapter in the other way then it in the end of a soda bottle and shake it up it would directionalize the spew of expanding soda and cause it too fly higher thank a bike pump
oh hai i is potassium nitrate? kno3 sugar rockets... the best kind cheap, easy quick and plenty of thrust... if you makem properly. blackpowder is also cool, just started playing with some, is fun!
Yes, potassium nitrate is KNO<sub>3</sub> , also known as <em>saltpetre</em> or <em>salt peter</em>.<br/><br/>Apparently it can be found as &quot;stump remover&quot;.<br/>
or you can boil down pee to make it...
&nbsp;I'm sure that's phosphorus - and it takes gallons of pee, high temperatures and a lot of time to make tiny amounts.<br /> <br /> Saltpetre is made by regularly pouring large amounts of urine on a pile of cow dung and straw as it rots down for a few weeks.<br /> <br /> Don't ask me how they discovered either of those things. (Actually, I know the first one - it was an alchemist who thought that because of its colour, urine must contain gold.)<br />
The second one is because saltpetre is highly soluble in water and, as such, tends to collect around the upper edges of undisturbed manure piles as the water evaporates out of them.
or you can get it from the internet. inoxia chemical supplies do a reasonable deal.
I guess we need an Instructable on this . . . . . . Okay, first I&nbsp;need to drink about 10 pints of <strong>Old Knackers Heavy Bitter</strong> . . . . . . then . . . . . ??<br /> <br /> (and don't forget the pictures of every stage&nbsp; :LOL: )<br />
Potassium nitrate can also be extracted from many natural sources, such as nitrate bearing earth.
if u mix KNO3 with sugar and then burn it u get a buttload of smoke
pee aside, KNO3 CAN be found as stump remover, in america at least, idk about the rest of the globe.
I've got an idea<br> Using some ultra-tech hi-cost toilet paper, you could separate the AS from the water... until it's flipped. Then, they would come in contact, and... BOOM! An instant, easy to carry AS rocket! Just take care not to flip it as an accident.
Yes, that works well.
Also, sorry for the horrible drawing, it was done on MS Paint with a mousepad.
Whoa sweet Kiteman! Are you from the U.K? People from their are always cool =P<br>
I am.<br><br>Cool? I try.
Haha. I think you are one of the best people on Instructables right now! I love this website so much. Me and my friend were making Altoids Tin boats all day yesterday!
I hope you took plenty of photos to write up a step-by-step Instructable?
Actually, we used this one that's already posted, then did a little tweaking and improv.<br><br>http://www.instructables.com/id/Rubber-Band-Powered-Altoids-Boat/<br><br>Sorry can't make links for some reason...my computer can but I forgot how. =) Copy and paste it?<br>
Had it been MY article, this step would have been the very first one...maybe more general in order to not share EVERYTHING you were doing!
I see your point, but piling on the nanny stuff up-front tends to put people off, and it's generally assumed that readers will go through *all* the steps before actually following them.<br><br>
A mortar is actually closer kin to a cannon...modern mortars use a twelve-gauge shotgun shell minus the shot to power a fin-stabilized projectile. The mortar shell looks like a rocket due to its shape and its fins.
this is all $#!% teehee hee ^_* <br>
I hope that's a wink on the end...
someone really neads to make a instructable on water roket launchers for BIG rockets.i cant find a one thats compatible w/ the one in the instructable cynobite made!!!!!!!!!!!!!!!!!!!!!!!!! HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! please?
Got a link?
cooooooooooooooooooooooooooooooooollllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll! 6 stars! (i dont care if theres no such thing)
Hi That is interesting, Instead of a rubber bung and a football pump valve, when I did this I used to use a Woods bicycle tyre valve and the actual cap of the bottle. I drilled a hole the same diameter of the Woods valve and then wrapped a small amount of paper masking tape around it and inserted it into the cap. Same method as you but when the pressure was too much it forced the valve out of the cap. To stop tumbling we used to get a 50 foot length of plastic coated clothes line and then duct taped a copper tube to the rocket and fed the clothes line through it. It was a tad safer and was guided
Copper tubing? Dangerous! Read the Instructable again, metal is illegal. Have Fun!! - but be careful!
I believe he meant the copper tube was attached to the outside of the bottle, the clothesline passed through it, and then tie the clothesline off at both ends.&nbsp; The bottle then rides along the clothesline.&nbsp; A good solution for school teachers with administration that is sensitive to rockets or other things that go up in the air as in our school system where the kids have to use tennis balls to play baseball - &quot;so no one gets hurt.&quot;<br />
That is correct SJU87, it is taped to the outside of the bottle as a guide<br />
I feel really good about myself now, after months of deliberation (or just not having the right stuff) I finally made it. It's amazing how high it can send it, but it's sort of annoying because you have to shove the cork in impossibly hard, other wise it comes out too easy. Anyway, thanks for introducing me to H2O rockets!
You're welcome!<br/><br/>If the cork thing is a problem, there are projects around for launchers that restrain the rocket until you want to launch is, like <a rel="nofollow" href="http://www.instructables.com/id/water-rocket-launcher/">this one</a>.<br/>
Yes, after finding out how much fun launching rockets 20 metres into the air was I thought I'd research how to make it go double, or triple, that. I've got a new launcher planned that shall retain the bottle until pressure is right. I'll deffinitely need a new pump though, I'm borrowing my step dad's which is a foot pump & 10 years old, the pressure guage does not work well plus it actually leaks air/water back out when under pressure. A heap of hot glue sort of worked, but now it squirts out doubly far but at least not as much. By the way, what's with the new blurred images everyone's putting up?
(I don't know <em>what</em> you mean)<br/>
Display picture, you've changed it now.
You're behind the times, my friend.

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