Water Rocket Parachute Deployment Mechanism

There are different ways to eject parachutes from water rockets. The technique we like to use is called Side Deployment (aka Horizontal Deployment) where the parachute is deployed in a perpendicular direction to the rocket body axis. The other common technique is to separate the nosecone and have the parachute come out in-line with the rocket axis. This is how most amateur pyro rockets do it.

We use the side deployment technique because we often have a camera and altimeter mounted in the nosecone. Having them rigidly attached to the rocket body gives them a more stable platform on the way down.

There are a lot of different ways to achieve side deployment as well. We like to construct ours so that the outer aero-shell is separate from the actual mechanism itself. This makes construction and adjustment much easier. It also allows the mechanism to be easily reused if the aero-shell becomes damaged.

The procedure below outlines the general steps of how we construct ours. No specific dimensions are given here as these will depend on the bottles you use and how much space you want to allocate for the parachute.

Materials

- Corriflute (Coroplast, Twinplast, Correx ) corrugated plastic sheet
- 2 PET bottles
- Cardboard
- 2 rubber bands
- Paper clip
- String
- Wire
- Skewer stick
- Ping pong ball
- Timer (Tomy timer, flight computer etc.)

Tools

- Tape
- Contact glue
- Scissors
- Craft knife
- Long nose pliers

More water rocket instructions such as these can be found at our main website:
www.AirCommandRockets.com

Step 1

Get a clean bottle with a nice aerodynamic shape and straight sides. Remove the label and clean off the glue with mineral turpentine.

Comments

[ianstein951]

Beautifully done!

[Ishrat]

dude i wanna ask how to make that parachute stuff can u plzz tell me step by step cause i wanna make this thing can u buy that stuff somewhere maing's better though

[Ishrat]

dude i wanna ask how to make that parachute stuff can u plzz tell me step by step cause i wanna make this thing can u buy that stuff somewhere maing's better though

[superboe]

 LOL
hobbking servo

[louwhopley]

I know this sounds stupid but where's the center of gravity supposed to be on a water rocket? i will be fitting mine with this parachute mechanism plus I am using RC to control the parachute to try fly it back to me.

[air.command]

Actually it is a very reasonable question. You should always work out the Cg for a dry rocket. This is because most of the flight the water rocket actually has no water in it. The Cg should be about 1.5 rocket diameters ahead of the Cp. When flying with fully open nozzles the water is ejected in the first couple of meters of flight so there really isn't that much time for the weight of the water to have an effect on stability. When flying with restricted nozzles you tend to want to make the rocket a bit more over-stable, ie. move the Cg a bit further up as the water stays in the rocket longer. Very good idea about flying the rocket back under parachute. :) Will you be using some kind of steerable parafoil?

[oscarthompson]

When making your Instructable, I found a few problems (with my build). As I am using a "tommy timer", I found that half a rotation of the wheel, pulled the pin out within 2 seconds. I have an 'arm' on the slowest moving wheel (to connect the string to, like your servo) When I twist it once round, the pin is pulled out releasing the parachute, like I said "within 2 seconds", which unfortunately is a bit to short of time for when I want my parachute deployed. I do not intend to fault your design, but I have found a way on how to fix this. Instead on having a pin pulled out i now wrap an elastic band around the rocket to keep the door shut and then wrap it round the "tommy timer". When that un winds it releases the parachute. I think your design is brilliant, along with the instructable. I'm just saying this so if someone designs it with a tommy timer and have the same problem, they can fix it. If there is a way to fix it.. I would like to know Thanks Oscar

[louwhopley]

I've only got 2 servos - so if all fails i would make it deploy two parachutes, one high up when rocket is starting to fall and the other a few feet from the ground for a perfect soft landing - haha

[louwhopley]

yes, I am investigating the use of a parafoil like parachute. ...still looking into designing the shute though, from scratch (my parafoil kite is a bit to big) I have got all the details to build the rocket from your site - thanks!

[i make shooting things]

Thats amazing, how high dose it fly (sorry i just skimmed the ible)? Do you have a video of it launching? iv seen thinks like this but never this intricate.

[air.command]

This particular rocket goes to around 400 feet. Here is a bigger rocket that uses the same parachute deployment mechanism.

[oscarthompson]

I have made a professional water rocket guide on instructables.
It also has drop away boosters but the are different to yours....

If you would like to check it it please go to http://www.instructables.com/id/Professional-water-rocket-guide/ or it apears to be in the realeted at the bottom of this page

[Plasmana]

That is amazing, it must been difficult to build and pressurized that rocket..

[i make shooting things]

thats amazing, multistage water power

[stunami]

Is there an instructable to make this rocket?!

[air.command]

Hi stunami,

There is no "Instructable" but we have instructions on our website on how to make the different components for this rocket and then you can assemble them into one that looks like this.

Here:
http://home.people.net.au/~aircommand/construction.htm

and here:
http://home.people.net.au/~aircommand/construction_2.htm

[oscarthompson]

do you have problems with the centre of gravity with this rockets with the boosters at the bottom of the rocket?

[air.command]

Yes and no. Just after liftoff the rocket is way too tail heavy and the Cg is actually behind the Cp, but the water drains very quickly so that in less than 1 second the rocket is stable again. We use a 2m long guide rail to try to get it pointing in the right direction as it builds speed. In an earlier rocket the fins were a little on the small size and we did get unstable flight during the initial part of the flight. Increasing the size of the fins fixed that problem up.

[stunami]

Thanks!

[831]

u shod show it cumin back down after but that is so good wot u have made u shod now move on to putin a camere an the record goong up that wuold be god an ther r sum good 1 that u can use

[Lftndbt]

Very impressive indeed!! That is alot of content there. Excellent write-up. I see you found some free time, nice. ;)

[oscarthompson]

I have checked there (or his/her) website, Its amazing. They have deatialed instructions on how to make drop away bosters, recovery system and lots of over intresting things. I will try and get an instructable in which will be a long guide about water rockets recovery, pressurizing, luanching and other things i hope to make i at leat 40 steps long

[oscarthompson]

I will probaly not use the air commands launcher but one of nasa's water rocket launchers.

[Xellers]

Very Well Done. 5 Stars!

[altomic]

when I was living in Japan I watched a show on TV which was a water rocket distance competition. The winner was a 3 stage rocket. from memory it went about 540 meters (distance) though it may have been more. it was very cool. - it was made up of - 1st stage :8 bottles, 2nd stage:4 bottles, 3rd stage:1 bottle it was a monster and the pressure needed to drive it was monstrous. it was the most impressive thing I have seen on TV for ages. sorry to distract. nice instructable

[F-35JSF]

were can u get the pdf for the rocket I have made the mechanism jus need the rocket pdf plzz

[MOHAMMAD_MS_MS]

In the name of GOD You are not inventor . You are ARTIST . This is the beutifullllllll. This iS WOW. Thanks alot .

[Ghost Wolf]

wow that is big and very heavy does it go as high as a model rocket

[mortso]

Does anyone in the SF Bay area have an interest in Building these? I have the stuff, knowledge etc. but have been having trouble finding people willing to have FUN ! C'Mon... Let's go Shoot for the Moon! email [e-mail] if you do..

[Wyle_E]

I remember little low-pressure water rockets I had as a kid, and I've seen the crude ones on Mythbusters. After following your links it was a real surprise that anyone had taken the idea this far. Have you tried reinforcing a bottle with fiberglass strapping tape? It's ugly, but amazingly strong. Have you tried building a boost-glider? With a tilting mirror to shift the camera's line of view from back along the rocket to straight down in glide, you could get some really nice video. The glider stage wouldn't have to be powered; your rockets could get it high enough for a good view.

[air.command]

Hi Wyle_E,
Yes, we have done tests with fiberglass strapping tape, and you are right it is great stuff and does a good job of reinforcing bottles and FTC tubing.

We have not made a boost glider yet (too many other projects :) ) but there have been plenty of people who have. They have made them remote control and have put cameras on them.

If you are interested, in the water rocket recovery guide:
http://home.people.net.au/~aircommand/recovery_guide.htm
you will find some examples of boost gliders people have made for water rockets. Scroll down to the Glider/Wings section.

There are some links to good YouTube videos of onboard footage from the gliders.

Cheers

- George

[ewilhelm]

Excellent Instructable! I see a couple of techniques on your site for increasing pressure and volume. A general tips for water-bottle rocketry Instructable would definitely be well received.

[Lftndbt]

LoL, I have been bugging him for months. He has been busy over christmas, but it looks like he is back in business now. His knowledge and write-ups are second to none on the net. I am glad he has chosen I'bles to use as the knowledge is well placed. Thanks for featuring as the "splicing bottles" I'ble should have been better recieved I must say.

[Kiteman]

Thanks for featuring

You're welcome ;-)

[Lftndbt]

Sorry your comment was at the bottom and I saw eric's first, then commented. I just assumed it was his. Good to see you have overcome your pixelitus.

[Kiteman]

;-)

[Kryptonite]

Your site is amazing, 194m into the air is amazing!

[acaz93]

Amusing , Yours is a great instructable !!

[air.command]

Thanks for the positive feedback everyone. :) We'll try putting up a few more instructables this year, as time permits. Thanks also to Lftndbt for encouraging us to put stuff up on Instructables.

[Lftndbt]

Congrats on the Feature!! I took the liberty of adding it to Make and my group also.