Building an Overhead Water Rocket Launcher

8/3/2019 Building an Overhead Water Rocket Launcher

1/11

BUILDING AN OVERHEAD WATER

ROCKET LAUNCHERMATERIALS AND TOOLS LIST FOR THE WATER ROCKET

You can get the materials from a building center or hardware store with a good plumbing department, and the tire valvefrom an automotive parts store. The video shows all the parts, or ask a clerk to help you identify pipe parts.

1 piece 1/2 inch (by the label not actual measurement, standard American pipe sizes do not represent actual

dimensions, either inside diameter or outside diameter), schedule 40 (schedule refers to the wall thickness of the pipe,schedule 40 is by far the most common available) PVC--not CPVC!--plastic pipe. It comes in 10 ft lengths, which isexactly how much you'll use. You can ask a clerk to cut the 10 foot length at 4 (or 6, depending how you look at it) if itmakes it easier to transport.

1 piece a short piece of 1 1/2" PVC schedule 40 pipe. Since you only need a 2" long piece, you might be able to get ascrap from someone handy. If you cant find a short piece of 1 pipe, Andrew Baillie has discovered that using a 1 slip connector works instead (this is not updated in the video instructions yet). And its already 2 long!

1 piece 1/2" slip Tee. Slip means you put glue on and slip it onto the pipe for a strong glue connection.

2 pieces 1/2" slip end caps.

1 piece 1/2" adapter, slip and internal thread.


2/11

1 piece 1/2" adapter, slip and external thread.

1 roll small roll teflon tape.

1 small canPVC cement. I prefer the kind with the applicator built in to the lid.

1 piece hose clamp that opens to at least 1" diameter

8 piecesmultipurpose ties (sometimes called zip ties), as close to 8" long (20 cm). They will likely be in the electricalsection of the store. Other sizes might work, but I know this size works.

3 feet of twine or thin rope

1 piecetire valve (sometimes called a stem). You get this from any auto parts store or a place that fixes tires might give

you one free. Either the long or short stem kind is OK and the cheap pull-on kind is fine (you don't need the expensivethreaded kind). If it is available in more than one diameter, you want the thin kind ( thanks to Ben Manvel for pointing out

the thicker size).

Optional 1 cheap air tire pressure checking gage. I recommend that people not pressurize the bottle to more than 70 psifor safety. it is hard to get much higher than that with a regular bicycle pump, so for most people it's good enough to pumpuntil it gets difficult, then launch. But if your tire pump doesn't have a pressure gage and you want to know, they are cheapin auto parts stores.

2 bottles empty 2 liter plastic bottles. You can shoot smaller bottles also, but you might have to cut off a bit of pipe so itcan fit on, and you might have to readjust the hose clamp/ zip-ties every time you switch between big bottles and littleones.

1 piecesandpaper, any grit

TOOLS and stuff around the house

marker


3/11

hack saw or any saw to cut plastic pipe

1/2" drill bit and a smaller drill bit about the diameter of whatever twine you end up using (listed above).

pliers (you might need a big pair to get the lid off the glue)

tape measure

candle

duct tape

scissors

air pump, with a pressure gage is nice (the foot operated kind has not held up well for me).

Part 1: Introduction and Overview, lets you know what you're getting into if you want to make the overhead waterrocket launcher featured on Ask This Old House during their special kids program. It uses inexpensive, readilyavailable materials. It peeks at how the launcher works: the bump that seals the water and air pressure in the bottle, thezip-tie assembly that holds it on, and the spring that helps prevent accidental launches. And part 1 asserts that shootinga water rocket is analogous to driving a car--potentially dangerous, but safe if done with care. If YouTube is blocked in

your school, try this SchoolTube link Part 1
http://www.youtube.com/watch?v=icQhLT4QCO8http://www.youtube.com/watch?v=icQhLT4QCO8http://www.schooltube.com/video/2b24c9cce326d5fb0337/Part-1-Build-an-Overhead-Water-Rocket-Launcher-Introductionhttp://www.schooltube.com/video/2b24c9cce326d5fb0337/Part-1-Build-an-Overhead-Water-Rocket-Launcher-Introductionhttp://www.youtube.com/watch?v=icQhLT4QCO8http://www.youtube.com/watch?v=icQhLT4QCO8


4/11

Part 2: Materials and Tools. PRINT FRIENDLY SUPPLY LIST CLICK HERE You can get the things you need at abuilding center, plus one thing at an auto parts store. The overhead water rocket launcher uses less than $10 US ofactual material. NEW! Observant correspondent Andrew Baillie of Atlanta discovered that you can substitute a 1 1/4"slip joint for the 2" of 1 1/2" pipe. Details here. If YouTube is blocked in your school, try this SchoolTube link Part 2
http://www.youtube.com/watch?v=KIKHSn24EJMhttp://www.sciencetoymaker.org/waterRocket/MATERIALS%20AND%20TOOLS%20LIST.rtfhttp://www.sciencetoymaker.org/waterRocket/makeBigPipe.htmhttp://www.schooltube.com/video/fa5b2fb4d94c48449d46/Part-2-Build-an-Overhead-Water-Rocket-Launcher-Materialshttp://www.schooltube.com/video/fa5b2fb4d94c48449d46/Part-2-Build-an-Overhead-Water-Rocket-Launcher-Materialshttp://www.sciencetoymaker.org/waterRocket/makeBigPipe.htmhttp://www.sciencetoymaker.org/waterRocket/MATERIALS%20AND%20TOOLS%20LIST.rtfhttp://www.youtube.com/watch?v=KIKHSn24EJM


5/11

Part 3: Install the Valve, Cut and Glue Pipe. You hook a bicycle pump to the launcher to pressurize the bottle. You drilla hole and install a common car tire valve. Then you can glue the plastic pipe together, which stinks (do it outside) butis not hard to do. You glue the pipe first so it will be strong by the time you are done with the rest of the launcher. IfYouTube is blocked in your school, try this SchoolTube link Part 3
http://www.youtube.com/watch?v=OfR_zWTyICEhttp://www.schooltube.com/video/fd7dcede27189685c7af/Build-an-Overhead-Water-Rocket-Launcher-Part-3-valve-pipehttp://www.schooltube.com/video/fd7dcede27189685c7af/Build-an-Overhead-Water-Rocket-Launcher-Part-3-valve-pipehttp://www.youtube.com/watch?v=OfR_zWTyICE


6/11

Part 4: Seal on a Bump. I worked in Bangladesh in South Asia for an organization that promoted inexpensive waterwells and hand pumps. It was there that I learned how to heat and form PVC plastic pipe. With only a candle you cancreate a little bump on on the small pipe that will seal in air and water while you pressurize the rocket. It's easier tomake than a seal with O rings and more durable, too. If YouTube is blocked in your school, try this SchoolTube linkPart 4
http://www.youtube.com/watch?v=jMK9wZPZ01khttp://www.schooltube.com/video/1bf73661e56b7b1d3d5f/Part-4-Build-an-Overhead-Water-Rocket-Launcherseal-bumphttp://www.schooltube.com/video/1bf73661e56b7b1d3d5f/Part-4-Build-an-Overhead-Water-Rocket-Launcherseal-bumphttp://www.schooltube.com/video/1bf73661e56b7b1d3d5f/Part-4-Build-an-Overhead-Water-Rocket-Launcherseal-bumphttp://www.schooltube.com/video/1bf73661e56b7b1d3d5f/Part-4-Build-an-Overhead-Water-Rocket-Launcherseal-bumphttp://www.youtube.com/watch?v=jMK9wZPZ01k


7/11

Part 5: Make the Trigger Mechanism. An Australian water rocket enthusiast named Ian Clark came up with a simple,effective trigger mechanism that uses ordinary plastic ties (zip-ties).If YouTube is blocked in your school, try thisSchoolTube link Part 5
http://www.youtube.com/watch?v=iZeTZuZfAkAhttp://www.schooltube.com/video/15fe3d60028d3eafbb46/Build-an-Overhead-Water-Rocket-Launcher-Part-5-triggerhttp://www.schooltube.com/video/15fe3d60028d3eafbb46/Build-an-Overhead-Water-Rocket-Launcher-Part-5-triggerhttp://www.schooltube.com/video/15fe3d60028d3eafbb46/Build-an-Overhead-Water-Rocket-Launcher-Part-5-triggerhttp://www.schooltube.com/video/15fe3d60028d3eafbb46/Build-an-Overhead-Water-Rocket-Launcher-Part-5-triggerhttp://www.youtube.com/watch?v=iZeTZuZfAkA


8/11

Part 6: Make a Safety Spring. A British Astronomer who--naturally--also tinkers with water rockets (sending up minivideo cameras) devised a simple spring that helps prevent accidental launches. Fittingly, it's made from a 2 liter bottleIf YouTube is blocked in your school, try this SchoolTube link Part 6

Part 7: Launch Tips, like how much water and how much pressure to put in, and tipping water out of the launcher aftereach use. And how to modify a bottle to launch water balloons! In addition to the video version, below you can find

more tips and answers, including some you won't find on the video. If YouTube is blocked in your school, try thisSchoolTube link Part 7
http://www.youtube.com/watch?v=0KReX192pbchttp://www.schooltube.com/video/9764b1c7dfd223139596/Build-an-Overhead-Water-Rocket-Launcher-Part-6-safety-springhttp://www.youtube.com/watch?v=N70frJm1piQhttp://www.schooltube.com/video/1297bae9dcf09ea1904c/Build-an-Overhead-Water-Rocket-Launcher-Part-7-launchhttp://www.schooltube.com/video/1297bae9dcf09ea1904c/Build-an-Overhead-Water-Rocket-Launcher-Part-7-launchhttp://www.schooltube.com/video/1297bae9dcf09ea1904c/Build-an-Overhead-Water-Rocket-Launcher-Part-7-launchhttp://www.schooltube.com/video/1297bae9dcf09ea1904c/Build-an-Overhead-Water-Rocket-Launcher-Part-7-launchhttp://www.schooltube.com/video/1297bae9dcf09ea1904c/Build-an-Overhead-Water-Rocket-Launcher-Part-7-launchhttp://www.youtube.com/watch?v=N70frJm1piQhttp://www.schooltube.com/video/9764b1c7dfd223139596/Build-an-Overhead-Water-Rocket-Launcher-Part-6-safety-springhttp://www.youtube.com/watch?v=0KReX192pbc


9/11

IF THE AIR PUMP LOCKS UP it's because too much water got into the launching tube and the check valve on yourpump is not working. Then water leaked into the pump. The check valve is a one-way valve that is supposed to let airgo out of the pump, but not go into the pump. It's on all air pumps, near where the hose goes into the pump, but it is

usually not accessible for repair. You'll have to unhook the pump from the launcher and pump out the water. To preventit from happening--short of getting a new pump--is to pump fast so there is little back flow and...

TIP OUT THE WATER IN THE LAUNCHER AFTER EACH USE

IF THERE IS A LEAK AS YOU PRESSURIZE THE BOTTLE you can readjust the zip ties for a better fit. If it's a hotday and you don't mind getting sprayed a little, you don't have to fix a small leak.

To adjust the launcher, loosen the hose clamp so you can slide the taped-together zip ties. You might want to mark on

the pipe so you know how much you are moving them. Move them just 1/16" or so at a time, toward the bottom of thelauncher to tighten the fit. If you move them too much you won't be able to get the bottle hooked on.

Very rarely, if the bottle has landed on hard pavement, the neck of the spout can crack, causing a leak.

HOW MUCH WATER depends on what you want. You don't have to put any water in the bottle, which might be goodon a cold day when you don't want to get wet. It makes a satisfying sonic boom when launched without water. Note,


10/11

however that the trigger mechanism has to be well adjusted (see above) because air volume leaks out much faster thanwater.

If you want to get wet, you can fill the bottle up to half full with water. However, if you fill it much more than that it

can be dangerous. Too much water displaces the compressed air, which is your stored energy source once the bottle isin the air. And the bottle is heavier, too, so a bottle with too much water might fall on someone before having ejectedall its water.

When launching water balloons (see below) I find that a bottle 1/3 full of water works well.

HOW MUCH PRESSURE DO YOU NEED IN THE BOTTLE? Depending on how hard you have the bottle jammedonto the bump, you will likely need 30 or 40 psi of pressure just to get the bottle off of the launcher. And you need thatmuch pressure to eject all the water before the bottle lands. Young kids will need some help getting the pressure high

enough.

So how much pressure is too much? I talked to a bottle manufacturer who said they can guarantee the bottle will notburst up to 100 psi, but that is a new bottle, unscratched and not crushed, not left in the sun for weeks, etc. Althoughyou can see internet videos of people bursting bottles at 190 psi, (http://www.youtube.com/watch?v=a_QvUC3EqxA ) Istick to 70 psi maximum. If you are going to go higher, use a different kind of launcher where you are not so close tothe bottle, and wear earplugs!

If your pump does not have a pressure gage, you can unhook the air-pump use a cheap tire gage from an auto parts

store to check the pressure. With a typical bicycle tire pump, it gets pretty hard to pump after 70 psi.

IF THE BOTTLE GETS STUCK ON THE LAUNCHER it could be that you need more pressure in the bottle (see howmuch pressure, above). Once, a bottle got stuck because the water inside was sandy. The sand lodged in between thebottle and the pipe, so even with a lot of pressure it would not launch. I was able to push off the bottle with my hand,still pointing up, of course. You can also disarm the rocket of its energy by unhooking the pump and pushing the insidecore of the tire valve, which will let the air out.
http://www.youtube.com/watch?v=a_QvUC3EqxAhttp://www.youtube.com/watch?v=a_QvUC3EqxA


11/11

WHAT ABOUT FINS ON THE WATER ROCKET? When we taped the Ask This Old House segment about waterrockets, I was the overhead launcher construction expert. But the shows producer, Chris Wolf, was the water rocketexpert. He made some cool rockets with nose cones and fins, and they soared really high, much higher than the plainold bottles that I launch. Bottles tend to tumble around in the air, creating a huge amount of drag, so they dont go as

high. Fins keep the low profile of the nose pointing up, so the rocket goes higher.

But we found that the upside of adding fins to rockets is the downside as well. Unlike a tumbling bottle, they speeddown hard and fast enough to possibly lacerate a scalp or break a windshield.

There're ideas on the internet for parachutes and other recovery devices to slow the descent of the rocket, but they'remuch harder to get to work than anyone thinks heading into it. So if you launch finned rockets, do it in a wide openspace with no kids or cars nearby.

LAUNCHING WATER BALLOONS Water balloons launched from water rockets go as high as finned rockets.Although the dense balloon would sting if it landed on you, it's unlikely that you would need stitches. I have heard ofpeople launching tennis balls, too. The simple modification for the bottle to launch balloons is shown near the end ofthe video instructions. Of course you still have to launch water balloons in wide open spaces sans young kids. And itgoes without saying that launching hard objects like stones could cause severe injury--or even kill someone.

Building an Overhead Water Rocket Launcher

Documents

Transcript of Building an Overhead Water Rocket Launcher