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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

Hovering contest

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Hovering contest

Post by RaZias » Sat Sep 13, 2008 10:29 am

Why not a hovering contest ?

A contest for the most stable and durable hovering.


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Re: Hovering contest

Post by WRA2 » Sat Sep 13, 2008 3:30 pm

These are very interesting suggestions but we have to increase participation in our current classes before we add new ones but some of the ideas could be submitted under the design and fabrication contest which will be coming soon. What we need to do is to find a way to increase participation in our Class C competition. Do you guys have any suggestions on how we could improve it to make it more attractive to participate in. We always thought that people would love the class C since there was no expensive altimeter to buy and that complex rockets made from exotic materials were not allowed. Please post any suggestions for improving the class C competition in this thread.

We look forward to your suggestions :WRA2:


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Re: Hovering contest

Post by RaZias » Sun Sep 14, 2008 10:36 am

The rocket must be done with a 2 L bottle or it can be with a 2 L cutted FTC ?
Can the FTC be reinforced with zip-tie ?

I belive the competition in class C is the "who makes the lightiest rocket"-"competition" because they have low volume and pressure...

I think the people don´t participate because is to much hard work just to make a rocket that will only go up a few meters...
Imagine the weight of " camera + parachute " being lifted by only 2 non-reinforced liters, adding to that the need to buy a mechanical pump that can go from 130-150 psi.

Maybe in this class compressors could also be used ?

I am not thinking in buying a pump right now...I prefer to spend money in creating new ways to reinforce a rocket.


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Re: Hovering contest

Post by Tim Chen » Mon Sep 15, 2008 12:07 pm

RaZias wrote:Why not a hovering contest ?

A contest for the most stable and durable hovering.
I think you could make a hovering rocket by putting pipes on the nozzle and dividing the thrust to 3 or 4 corner nozzles a few inches out to the side and pointing down. They just showed a car lifted into a hover using fire hoses on mythbusters last week, so you just need to build a rig to make the rocket work the same way.

I don't think the contest should be the most stable hover but rather the longest hover duration!


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Re: Hovering contest

Post by RaZias » Mon Sep 15, 2008 12:26 pm

If you see the Hawn Harrier jet it hasn´t several nozzles but only one pointing down.
The nozzle only angulates when it´s necessary impulse for horizontal movement.
(I just want a device fixed at vertical without horizontal movement)

The Eagle module that landed on moon is an example of one nozzle.
(anyway it was more a lunar rocket rather an hovering device...)

I think it´s better one nozzle with the weight distributed periferic and far from to it, like having four weights far and around it (like the legs of the Eagle module).


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Re: Hovering contest

Post by RaZias » Mon Sep 15, 2008 12:30 pm

Also one problem is the impulse should be controled so it would be a battle to achive zero speed and zero accelaration with variable (dropping) air pressure.

Like a variable small nozzle in the beggining that would get smaller at the end.


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Re: Hovering contest

Post by RaZias » Mon Sep 15, 2008 4:18 pm



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Re: Hovering contest

Post by RaZias » Mon Sep 15, 2008 4:47 pm

To keep a constant flow of air it would be necessary to use somekind of valve.
I know that when I press a the "valve-pistol" attached to the compressor it releases air at a constant rate...so it must have somekind of the valve or calibrator.

I don´t know where is the valve, if in the pistol or in the compressor.
Would it be heavy or is it just a little thing ?


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Re: Hovering contest

Post by WRA2 » Mon Sep 15, 2008 6:59 pm

RaZias wrote:The rocket must be done with a 2 L bottle or it can be with a 2 L cutted FTC ?
Can the FTC be reinforced with zip-tie ?

I belive the competition in class C is the "who makes the lightiest rocket"-"competition" because they have low volume and pressure...

I think the people don´t participate because is to much hard work just to make a rocket that will only go up a few meters...
Imagine the weight of " camera + parachute " being lifted by only 2 non-reinforced liters, adding to that the need to buy a mechanical pump that can go from 130-150 psi.

Maybe in this class compressors could also be used ?

I am not thinking in buying a pump right now...I prefer to spend money in creating new ways to reinforce a rocket.
Those are interesting points, When the competition was designed we required the manual pump to eliminate the need for reinforcements of the rocket and the high cost electronics. (We figured that everyone would have a pump for inflating bicycle tires). Would allowing air compressors help if we limited the pressure vessel to stock soft drink bottles?
How about some kind of annual prize for the longest duration? (our 1000 foot challenge seems to be very popular).

We do not think that it is just a lightest rocket competition as there are no restrictions on the type of recovery and it is more on designing the best recovery system (altitude is not really an issue as most 2 liter bottles will fly similar altitudes).

Any more suggestions would be welcome.


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Re: Hovering contest

Post by RaZias » Tue Sep 16, 2008 5:32 am

What are the caracheristiques of the recovery system ?
Can be an impact stopper or it must be something that slow down the fall speed ?
Right now I am making a light impact stopper (to protect the rocket when a parachute fails).

I think it´s kind of hard to a parachute work sucessefully from the small height it achives with 2 liters, but anyway I never made one so I don´t even know what I am saying.


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Re: Hovering contest

Post by Tim Chen » Tue Sep 16, 2008 10:10 am

RaZias wrote:What are the caracheristiques of the recovery system ?
Can be an impact stopper or it must be something that slow down the fall speed ?
Right now I am making a light impact stopper (to protect the rocket when a parachute fails).

I think it´s kind of hard to a parachute work sucessefully from the small height it achives with 2 liters, but anyway I never made one so I don´t even know what I am saying.
The first water rockets Mark and I ever built were just really 2l bottles with fins taped on and a paper nosecone covering a rolled up parachute. We would tape a plastic bag filled with sand to the inside of the nosecone we could get the weight set up so the air pressure would hold it on top of the rocket until apogee. If you launched vertically the rocket would peak at apogee and then fall backwards before the fins would turn it around. In this backwards flight the nose cone would be sucked off and deploy the parachute. It was very reliable and if it were to fail the nose would still fall off and the whole thing would tumble pretty harmlessly to the ground.

A single 2l bottle could go pretty high, especially with a small nozzle. Look at the ones Anti Gravity Research Sells. They show videos of 2l bottles going really high!


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Re: Hovering contest

Post by WRA2 » Tue Sep 16, 2008 6:50 pm

RaZias wrote:What are the caracheristiques of the recovery system ?
Can be an impact stopper or it must be something that slow down the fall speed ?
Right now I am making a light impact stopper (to protect the rocket when a parachute fails).

I think it's kind of hard to a parachute work sucessefully from the small height it achives with 2 liters, but anyway I never made one so I don´t even know what I am saying.
The recovery system can be whatever you wish it to be, even a "no recovery" (although that probably would not stand very long if you managed to get video and 2 flights). Parachutes, side gliding, helicopter recovery, even deploying wings and flying like a glider would all be acceptable. Imagine what the video would look like from a rocket that flies vertically and then deploys wings and flies back to earth with the camera looking with a "pilots view".


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Re: Hovering contest

Post by Bonami » Tue Sep 16, 2008 9:46 pm

WRA2 wrote:
RaZias wrote:What are the caracheristiques of the recovery system ?
Can be an impact stopper or it must be something that slow down the fall speed ?
Right now I am making a light impact stopper (to protect the rocket when a parachute fails).

I think it's kind of hard to a parachute work sucessefully from the small height it achives with 2 liters, but anyway I never made one so I don´t even know what I am saying.
The recovery system can be whatever you wish it to be, even a "no recovery" (although that probably would not stand very long if you managed to get video and 2 flights). Parachutes, side gliding, helicopter recovery, even deploying wings and flying like a glider would all be acceptable. Imagine what the video would look like from a rocket that flies vertically and then deploys wings and flies back to earth with the camera looking with a "pilots view".
What is the record timing the whole flight or just the fall to the ground from peak altitude? Thanks.



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Re: Hovering contest

Post by Tim Chen » Wed Sep 17, 2008 9:55 am

It's supposed to be the duration of the flight, so going slowly up can be seen as a positive. It's a balancing act of getting as high as you can and falling as slow as possible.


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Re: Hovering contest

Post by WRA2 » Wed Sep 17, 2008 9:46 pm

The contest is for total flight duration which means the timing starts when the rocket starts movement (when launch is triggered) on the launcher and ends when the rocket touches the ground. The flight is timed using the onboard video.


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