How much water to use in a water rocket

How much water should you put in a water rocket?
As a general rule of thumb, fill it 1/3 full of water.
For more information on the precise amount please see:
www.aircommandr...
More information on this experiment can be found here:
www.aircommandr...
Music:
Clean Soul - Calming by Kevin MacLeod is licensed under a Creative Commons Attribution licence (creativecommon...)
Source: incompetech.com...
Artist: incompetech.com/

[@anarchestra9411]

I enjoyed launching water rockets in the late 60's, early 70's. While 30% sounds right I was happy to see you actually test this idea with real measurements.

[@mjproebstle]

really enjoying your channel! done solid fuel model rocketry for years. your subject matter, approach and delivery are just great, informative even to someone that has been around rocketry, and just plain fun to watch, very well put together! thank you!

[@AirCommandRockets]

Cheers! Thanks for the nice words. :)

[@hcamaleon]

I really love your videos, i'm university student at Mexico, and i'd like if you can make one complete article on your blog to see how you design one rocket, calculates aerodynamics, the nozzle, simulations, etc..

[@AirCommandRockets]

Thanks for your suggestion Pedro. We have had several similar requests now for such an article. We will put that on the TODO list. :)

[@excellenceinanimation960]

Awesome video! I’m super glad I found your channel again after probably 7 years lol

[@AirCommandRockets]

Welcome back! :)

[@franktechmaniac7488]

I wonder whether a salt solution could improve the performance of the water rocket. Sodium acetate solution has a significant higher density than water and isn't any corrosive

[@AirCommandRockets]

For a deep dive on liquid density and how it affects performance see this video: kzbin.info/www/bejne/fKaWo3yfhd6SZ5o

[@RaketfuedrocketsDeutschland]

That's a great video George, I love the series! =) Very impressive how accurate these simulators are. I'm looking forward to the next video. Julian

[@AirCommandRockets]

+RaketfuedRockets Thanks Julian. Yes the simulators are pretty accurate in modelling the rockets.

[@algodude8713]

1:50 the crows are laughing at you for putting too little water

[@garfield_thedog1188]

a little late of a comment but where can i get the double sided caps for the rocket to connect multiple bottles?

[@AirCommandRockets]

Search for the term "Tornado Tube" on google. Here is an example: www.amazon.com.au/tornado-tube/s?k=tornado+tube

[@ScrapwoodCity]

Awesome science tutorial! Your water rockets are awesome!

[@AirCommandRockets]

+Scrap wood City Cheers :)

[@JustLifeTravels]

Really Great video!

[@johnarcidiacono9440]

Thanks I always wondered how much water to put and why it effected the outcome. Thanks a lot

[@AirCommandRockets]

You're welcome :)

[@RogerGarrett]

I'm trying to understand why putting ANY amount of water in an air-powered rocket makes it fly higher than using just the compressed air. Certainly the water adds considerable weight, plus it means less compressed air (less energy), so it would seem reasonable that it would fly not nearly as high as with just compressed air. In addition, in some of the videos it actually shows that some of the water that's exiting the nozzle is actually moving in the SAME DIRECTION as the rocket, which would seem to imply that it's not acting as exhaust contributing to the thrust. I'm thinking that the effect that the water has is that it keeps the internal pressure higher slightly longer than with an air-only setup, since the water isn't nearly as fluid I know that's not quite the right term) as the air, so it takes a bit longer to escape through the nozzle. Maybe the issue is that you're using the same nozzle size for both the air-only and the air-with-water launches. Maybe the air-only needs a smaller diameter nozzle and it would then reach a higher altitude. It just seems counter-intuitive that adding the relatively tremendous amount of water weight to the rocket and the significantly less pressurized air should result in higher altitudes.

[@AirCommandRockets]

It may seem counter intuitive. For a definitive answer here is a good explanation with equations and everything. www.et.byu.edu/~wheeler/benchtop/pix/thrust_eqns.pdf

[@pangolin7398]

Conservation of momentum and Newton's third law

[@oswaldoriginal5037]

I wonder will NASA ever consider water rockets as part of the booster, the advantage is that water spouting together with the flames can damp the noise from the raptor engines

[@AirCommandRockets]

No, water rockets are extremely inefficient.

[@TheChowster]

Thank you! This was super helpful.

[@T-bros]

Thanks so much for clarifying this with me!

[@istvanfrank9201]

Informatív és tanulságos kísérletek.

[@mangeshjoshi8627]

Can you suggest a mathematical way to calculate the optimal amount, like what equations are used to run the simulation. I did some calculations for my rocket but they don't predict between 25-45 % range.

[@AirCommandRockets]

Best way is to use a simulator. www.aircommandrockets.com/sim/simulator.htm or cjh.polyplex.org/rockets/simulation/ but if you really want the maths then this is a really good detailed explanation: www.et.byu.edu/~wheeler/benchtop/pix/thrust_eqns.pdf

[@mangeshjoshi8627]

@@AirCommandRockets Yes, i read your detailed description on the website. The pdf you sent was useful. Solved my problem. Thanks. 😊

[@bksduskmirror1250]

If you put a smaller opening at the bottom of the rocket, would that make a difference? Let say instead of a 1" opening, you go to 1/2" opening and increase the air pressure to 200 psi, like when you put your thumb at the end of a garden hose, it makes the water go further, wouldn’t it be the same with a rocket?

[@oak4901]

The German WWII tank (Super Tiger I believe) used two air powered rockets as antipersonnel fired vertically...

[@almodovar4897]

Thanks I needed that for science Olympiad

[@Danielastronomo]

A thought that came to mind. Supercritical fluids feature the density of a liquid and the viscosity of a gas. I wonder, how a theoretical rocket that runs on supercritical CO2 would perform.

[@AirCommandRockets]

That's a really good point. It would be interesting to do a test with that. :) A nice expansion nozzle too.

[@prof.nenobio]

Fun and educational. Great for elementary and high school. Congratulations George.

[@AirCommandRockets]

Thanks Neno. :) We have good fun doing these videos.

[@FirstLast-tx3yj]

​@@AirCommandRockets for some reason using a water rocket simulator at 20% gave me higher altitude than 33% for a 2.1L bottle

[@AirCommandRockets]

@@FirstLast-tx3yj Other factors come into it as well like the dry weight of the rocket and the drag coefficient.

[@AirCommandRockets]

1/3 water is a general rule of thumb that is a good starting point for most rockets, the optimum amount will vary slightly depending on various other factors. If you have a look at this graph it shows you the optimal amount to use depending on the size of nozzle and weight, all other things being equal. www.aircommandrockets.com/images/water/Water_2L_altitude.png Here is the full article on optimizing the water amount. www.aircommandrockets.com/water.htm

[@ericpham8205]

The secret of using water and air pressure is that we can replenish during fly because we can use fuel less electric and reproduce air and water and continuously compress and repulse to travel into space of around earth many many time. According ti my calculation, the ải water pressure of 6 stages each use 2 litter at 1200 psi so total missile weigh only 50 lb can be shoulder launch or base launch and 10 lbs war head can get to 5 km altitude at match 3 speed and if deliver by a drone at high altitude can beat even b52 at 50000 ft for bigger bmversion is only a few dollars more

[@nathanieljpruden]

How do the simulations change if you increase the density of the liquid? Say by using a 15% salt water?

[@nathanieljpruden]

Disregard. I just saw your video explaining this. Excellent videos!

[@human_3217]

now what if you launched a rocket with a proper CD nozzle, with only air? and also due to being so light you could have a larger tank?

[@AirCommandRockets]

We've compared water rockets with air+water and with just air. The air-only rockets went about 2/3 the altitude of water+air. A CD nozzle wouldn't make up that difference, but it would help.

[@ericphantri96734]

Thanks ...you are good professor

[@erichaskell]

Had a water rocket toy when I was quite young, doubt they are made as a toy now.

[@Pipizzakitchen]

Me too. That's what brings me here. My grandson will have one also.

[@zerxe_]

i dont know if 1/3rd is truly the ideal amount, but for the water rockets i built, 20-25% water almost everytime worked the best. But depends on the rocket.

[@AirCommandRockets]

Right, 1/3 is not always ideal for all rockets, but it is a good approximation for most rockets.

[@rajuujar3298]

Thanks bro

[@richardsleep2045]

Thanks, that's interesting and fun.

[@okboing]

Helpful information. Thanks!

[@rock3tcatU233]

This is great stuff!

[@asusiotab3568]

Do i need kangaroo to lunch water rocket?

[@pangolin7398]

Yes.

[@yottaplex2239]

does adding boosters make you able to use more water in the centre stage since you increase the total thrust on the vehicle at liftoff, so that the heavy core is able to lift itself normally and achieve a longer thrust duration?

[@AirCommandRockets]

Interesting question. So yes, the boosters would allow you to add more water to the center core to get a longer duration thrust, if thrust duration was what you are looking for. However, it will result in less altitude because you are adding more weight to the whole system and so you will use up some of the performance of the rocket to overcome this added weight. Secondly the core stage will under-perform because you now have less air in it (shared volume with the water) It is the compressed air that provides the energy. Having less air means you can store less energy. The 1/3 water to 2/3 air ratio still applies as optimal here. But you are on the right track of wanting a longer burn. The longer burn can be achieved by reducing the nozzle size. This way you stretch out the burn over a longer period while still retaining the correct water/air ratio. The boosters allow you to get a rocket up to speed with a relatively small nozzle that normally wouldn't allow the rocket to get off the pad by itself. A longer burn allows you to travel slower for longer meaning you induce less drag. Since drag is proportional to the square of the velocity. So you can get somewhat slightly better performance that way as well.

[@yottaplex2239]

@@AirCommandRockets but isn't ballistic trajectory based on an initial velocity V0 minus the drag and gravity acceleration? In this case, a higher V0 is going to result in a longer coast phase, therefore a higher altitude. Regarding the adiabatic expansion, that was our main concern when adding propellant to the centre core. We just didn't properly understand how to apply it mathematically in our simulations. In a previous video, you stated that plain PVC pipes don't work well as high pressure vessels. We found ratings for 80 PVC pipes and found out they can withstand over 600psia of pressure... Is there any reason behind the material strength why it can't withstand any higher pressures that a regular PET bottle?

[@AirCommandRockets]

Ballistic trajectory is also dependent on the initial altitude. Ballistic trajectory happens when you stop producing thrust. So with a faster burn you get higher velocity (and higher drag), but you start at a lower altitude compared to if you stop producing thrust later in the flight with a slower velocity. In the end there isn't much of a difference between the two altitudes. I'm not saying you can't use a PVC pipe for a rocket, but you can't easily compare it to a PET bottle. If the narrower PVC pipe with it's wall thickness can hold 600psi, you can't compare that to a PET bottle that bursts at 190psi. To compare the two, make a PVC rocket the same size/weight as a PET bottle. I am not trying to discourage you from experimenting, I'm just providing information based on what I have seen over the years people attempting to make rockets out of PVC and why you don't see it very often. If you are going to pressurise PVC to its limits be careful of the shards that will be generated when it lets go. Stay at a safe distance.

[@yottaplex2239]

@@AirCommandRockets we will! Thank you for your precious advice. Good luck with horizon!

[@aidanmarshall8469]

Which rocket is this

[@AirCommandRockets]

This is a water rocket.

[@pieromartinmendiburomerino7233]

thats an amzing explication now i know how much water do i have to put. But i have a question maybe you can help me. How much fins do i have to put in my rocket water 1 ,3 or 5? or maybe without fins?

[@AirCommandRockets]

+Piero Martin Mendiburo Merino That's a really good question. If you are talking about normal flat fins, then a minimum of 3 is required, and 4 will give you a little more stability with smaller fins. 5 or more fins will generally tend to have a negative effect on altitude because you are increasing drag and weight without adding to stability significantly. You could potentially use 1 or 2 fins but would need to spin up the rocket to get stable flight. Of course you could also use a single ring fin without needing to spin the rocket.

[@pieromartinmendiburomerino7233]

ok thanks a lot for the answers. and one more question if i don't have fins in my rocket what will happen?

[@AirCommandRockets]

+Piero Martin Mendiburo Merino That depends on your rocket. If your rocket is fairly short it will most likely tumble end over end and not go very high. You need to make sure your rocket is aerodynamically stable in order for it to fly straight.

[@oscaranderson1822]

I would like to take about a 10,000 gallon air tank place it under a boat hull and pull water in from the ocean around it. There would be no fuel weight Boat design calls for 3 Hulls. Roughly thirty thousand gallon total. Botas designing at 87 ft length by 40 ft width. I am looking for suggestions on nozzle diameter.

[@AirCommandRockets]

Depends on how much pressure you intend to use.

[@Skyliner_369]

would higher air pressure allow more water to be stored in the rocket or is the efficiency independent of pressure?

[@AirCommandRockets]

It is mostly independent of pressure, though there are slight variations if you want to get super optimal.

[@Skyliner_369]

@@AirCommandRockets Thanks! that's actually pretty helpful! That means that there's not as much need to fiddle with the water as pressure increases. On the other hand, now the question is treating the water, or using other liquids. after all, a heavier fluid will give more ΔV per launch... but that's an entirely different thing.

[@AirCommandRockets]

Yup, here is a video that covers different liquid densities. A denser liquid will result in more thrust but not necessarily higher altitude. kzbin.info/www/bejne/fKaWo3yfhd6SZ5o

[@kaikeuning2762]

Nice question Henry

[@michelleli4142]

Hi, may I ask how you deployed the parachute?

[@AirCommandRockets]

Here is a full tutorial on how we make our deployment mechanisms: www.aircommandrockets.com/construction_7.htm

[@MultiSegelflieger]

Again: Nice Video! By the way: How do you trigger the Parachut of this Rocket? Do you use your timer or another Method? I am currently devoloping a deployment-mechanism with an Arduino nano as the main component. I was wondering what Sensortype would be more practical: A G-Sensor or a Barometric Sensor? What do you think? Keep on the good work! Love your Videos!

[@AirCommandRockets]

Thank you MultiSegelflieger, We use our timers for these rockets. I would highly recommend a barometric sensor for your project. There are some great breakout boards available on the net that have the barometric sensor and support components built on so all you need to do is talk to it from the Arduino. One thing to keep in mind is to keep the sensor out of the sun, otherwise you can get false readings. Good luck with the project.

[@MultiSegelflieger]

+AirCommandRockets Thank you very much!

[@Cardstacker]

For fun, I'd like to see an 80 or 90% water launch, with perhaps a longer launch pole. Or with boosters...

[@AirCommandRockets]

I agree, it would be interesting to see. You'd also would want to make sure the rocket is stable when it's that full. You wouldn't want it flying out of control at the launch site. Probably a bigger nozzle would be useful in that case.

[@Cardstacker]

+AirCommandRockets Exactly... when my brother used too much water early on it was a beautiful slow lunch but it went nearly horizontal at very low altitudes (10-15 feet!!) which is of course not the the safest situation lol.

[@martkt10]

I wonder if the type of water would affect the thrust, say if you used carbonated water (fizzy) , would this aid or hinder ?

[@AirCommandRockets]

It's a good question. We do use foam in our rockets and it definitely helps performance.

[@RhyssRocketProject]

LOL kangaroo's hopping across the field !

[@AirCommandRockets]

+The Dream Duo Space Program They were back again last launch and got a whole lot closer to the launch pads. :)

[@m.s.l.7746]

Why not fill it completely & have a stage of compressed gas to charge it continuously?

[@AirCommandRockets]

? I am not sure I follow. That is exactly what happens in a water rocket.

[@Pipizzakitchen]

I'm thinking the same thing. Like a flamethrower works.

[@hastrinam.salleh5072]

I have a question if I try to use the same amount of water but the pressure is 90psi could be the altitude of the rocket similar to your results? or the results would apply when applying the 210 psi only

[@AirCommandRockets]

I am not sure I follow, are you comparing your rocket to the experiment? Your rocket should still roughly use 1/3 water. That will optimize the altitude for that rocket. At lower pressures it will fly lower and higher pressures it will fly higher.

[@jraschke]

Have you considered adding salt to the water to make it heavier?

[@AirCommandRockets]

Yes, Here is a video that looks at liquid densities and how it affects performance. We used sugar instead of salt as we'd rather feed the ants at the launch site than kill the grass. :) kzbin.info/www/bejne/fKaWo3yfhd6SZ5o

[@parulverma2475]

Hello, how to subtract buster rocket , main rocket

[@parhamray4843]

Hello AirCommand I'm only 12 and I wanted to make a water bottle rocket I don't want to go too big only one bottle I know all the aerodynamics but I want to make a launch pad how could I make a cheap easy launch pad for pressurising rockets and have a release cord PS: could I get all the materials at bunnings? Thanks!

[@HardikKundalwal]

Can we use other fluids in water rocket?instead of water

[@AirCommandRockets]

Sure, you can also use non-fluids as well. Here are some examples: kzbin.info/www/bejne/aYKyd2eqpqeIn9U and kzbin.info/www/bejne/fKaWo3yfhd6SZ5o

[@tiitsaul9036]

very interesting stuff.

[@aaronramirez3414]

How much water does a 3 letter bottle needs I need it before Monday, if you please can answer. Thanks

[@AirCommandRockets]

1 Liter of water.

[@aaronramirez3414]

@@AirCommandRockets what if the bottle is 2 liters? Thank you very much

[@AirCommandRockets]

About 650mL ... Use 1/3 of the volume of the rocket.

[@aaronramirez3414]

@@AirCommandRockets thank you very much

[@ScreenPrintR]

Why do you color the water?

[@AirCommandRockets]

Makes for better looking photos and videos :)

[@francuadasilvacosta5116]

WHAT TYPE OF TELEMETRY DO YOU USE?

[@AirCommandRockets]

We haven't done any telemetry yet, as in send live data to a ground station. We do collect on-board data though including barometric pressure (altitude) acceleration in 3 axis, temperature. Velocity and acceleration are derived from vertical distance.

[@francuadasilvacosta5116]

@@AirCommandRockets your channel is very good, I am in a school project and I rely on your channel to see your rockets, they are really good. Thank you very much!

[@AirCommandRockets]

@@francuadasilvacosta5116 Thanks, glad to hear that the videos are useful. :)

[@WATERROCKETSCLUB]

Great job! Very cognitive video.

[@AirCommandRockets]

Thanks +WATER ROCKETS CLUB :)

[@priyanshbhatter9338]

Hi sir, can you provide an equation to prove your experiment please

[@AirCommandRockets]

www.et.byu.edu/~wheeler/benchtop/pix/thrust_eqns.pdf

[@priyanshbhatter9338]

@@AirCommandRockets thank you so much!!!

[@priyanshbhatter9338]

@@AirCommandRockets hi sir, sorry to disturb you again but actually I am not able to understand the whole document. Can you please provide me just the equation to show the relationship between the amount of water in the rocket and the height reached by the rocket. Otherwise can you tell me the page number where this equation will be present. Thank you so much😄

[@AirCommandRockets]

@@priyanshbhatter9338 The document describes the motion of a water rocket in detail. It is not simple. There is no simple equation that just relates the amount of water to altitude. There are many interrelated parameters that need to be considered when working out the final altitude. Simulators are typically used to calculate the predicted altitude based on the various parameters. www.aircommandrockets.com/sim/simulator.htm and cjh.polyplex.org/rockets/simulation/

[@coringaringa]

Hello, how can I calculate the rocket's distance in the air?

[@AirCommandRockets]

There are quite a few factors that affect the final altitude of a rocket. It is best to use a simulator to calculate the rocket's apogee. For example: cjh.polyplex.org/rockets/simulation/ if you want to know how to measure actual altitude please see: www.aircommandrockets.com/day171.htm

[@tvu5652]

How did you measure the altitude of the rocket?

[@AirCommandRockets]

We use a commercial altimeter. The altimeterOne from Jolly Logic. www.jollylogic.com/products/altimeterone/

[@momochionichan5329]

can you teach me more detail about the rocket.

[@AirCommandRockets]

Sure, what do you want to know?

[@momochionichan5329]

+AirCommandRockets what material that i can use to make rocket body and what size you recommend

[@mrbshow5596]

how you lift it up

[@nalandasouza3131]

Show.

[@kishoreb1213]

Sir may i know the applications of water rocketry

[@AirCommandRockets]

Water rockets are primarily used for teaching science. Though you can use them to carry payloads and do experiments with them as well.

[@AmIonArock]

WOW you have started a new. culture

[@3dannsiki]

60% water? ? It is not a water rocket! It is a real liquid rocket!

[@tshiamomatiza9008]

HI GUYS Am Tshiamo from South Africa love your videos watch them all the time,Can you guys please help me,Am stuck here at home with my water rocket and the is a competition coming in 2 months time,can you guys make a tutorial video on how to make your water rocket boosters separate from your rocket like in the (Water Rocket with Boosters - Axion G2) video PLEASE GUYS I REALLY REALLY NEED YOUR HELP,PLEASE RESPOND TO MY QUESTION AS SOON AS POSSIBLE.

[@AirCommandRockets]

Hi Tshiamo, Although we don't have a tutorial here is an explanation of how it works: www.aircommandrockets.com/howitworks_1.htm#DropAwayBoosters The principle is very simple, as long as the boosters create greater thrust than the main stage, then they stay in place, and slide out when they stop producing thrust. The actual implementation will depend on your rocket design and the type of launcher you are using.

[@tshiamomatiza9008]

AirCommandRockets thank you guys you guys are the best🙋

[@digitalmorgan]

ok.. i get it...the water is the ladder.

[@ericphantri96734]

If addon electric heater stage using motion spin turbine generator supply electric to heater make it real powerful

[@AirCommandRockets]

You wouldn't be able to heat the water fast enough. In a small rocket like this, it has about as much water as a tea kettle. Try boiling all that water in half a second. Also any generator is going to add weight and drag.

[@asdfasdfdf6834]

hello from Serbia

[@Bryan-ot1yz]

awesome science tutorial if the rocket is filled with liquid nitrogen only what will happen

[@AirCommandRockets]

+Bryan Ang Good question, I'm not really sure. I guess it would depend on how quickly the nitrogen would boil off and how much pressure could build up at the top of the rocket to start pushing the liquid nitrogen out of the bottom. If you held the rocket sealed for a while you would probably build up enough pressure.

[@cuthon3574]

Finally...

[@johnnyllooddte3415]

what about foam ahahahahha like pulling teeth

[@aulialuftiani11to4]

cool bro

[@ominousscreech4054]

I challenge you to get a water rocket to 5120 feet, after I challenge a solid motor stage then the second stage a water stage 1.8 liters at 200 - 400 psi

[@AirCommandRockets]

+Jirreh Smith Why 5120 feet?

[@tshiamomatiza9008]

Good day Team AirCommandRockets its Tshiamo again from South Africa,Thank you so much for responding the last time I ask you guys a question.So guys quick question,How did you guys make the rocket launcher in the (Axion G4 rocket with BOOSTERS) video??Because most of the videos here on KZbin only shows you how to create a single water rocket without boosters launcher like the video on this link:kzbin.info/www/bejne/naqyq6mnorqmasU (PLEASE HELP GUYS RESPOND AS SOON AS YOU GET THIS VIDEO)

[@tpsr1193]

sir what shud be the water amount if pressure must be fixed to 50psi

[@AirCommandRockets]

+Tanuj pal singh rathore What is the capacity (volume) of your rocket?

[@tpsr1193]

+AirCommandRockets sir it's 2 litre

[@gk123434534]

+Tanuj pal singh rathore Try using around 650-700mL of water.

[@tpsr1193]

+gk123434534 OK sir

[@momochionichan5329]

can you teach me more detail about the rocket.