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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.

Dual Parachute Deploy Modular Nosecone

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
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thampson
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Dual Parachute Deploy Modular Nosecone

Post by thampson » Mon Oct 06, 2008 12:42 pm

Hi everyone,

I have been working on this for the last week, very windy and raining here so no chance of testing it yet. I have put some videos together of the dual deploy system and the modular construction. I havent made any changes to the airflap systems as yet, we will have to see how much drag two of them have.

Here is a video of our modular approach. This is the PPNC module with main chute, drogue module and pressure bottle. I have designed it this way so I can add other modules later (payload / cansat module, camera, alt etc) or remove a module if I dont need it. It will also make fixing parts in the field easier if I take some spares and can swap them in and out easily. These modules will normally be taped together before flight

[youtube][/youtube]

This one is the test of the dual deploy with parachutes loaded.

[youtube][/youtube]

Am looking forward to a calm day to give it a test powered by our 2 bottle 2.5L wrocket

-todd-
HHWRSA


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Cloud Dancers
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Re: Dual Parachute Deploy Modular Nosecone

Post by Cloud Dancers » Tue Oct 07, 2008 12:14 pm

Very impressive modular system. I like the idea of having seperate sections for each purpose. That way you can customize the flight for multiple purposes and not have to "carry everything" all the time. That saves weight.

I look frward to seeing your test flight. Hope your weather clears soon.


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Re: Dual Parachute Deploy Modular Nosecone

Post by Graveyard » Tue Oct 07, 2008 9:20 pm

Yes...very nice !! where do you get the little timers?



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Re: Dual Parachute Deploy Modular Nosecone

Post by reno1 » Tue Oct 07, 2008 11:19 pm

Graveyard wrote:Yes...very nice !! where do you get the little timers?
Hi Graveyard this will help http://waterrocket.uh-lab.de/tomytimers.htm


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thampson
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Re: Dual Parachute Deploy Modular Nosecone

Post by thampson » Wed Oct 08, 2008 8:01 am

thanks graveyard. I have pics of the tomy timers in their packages on this URL on our blog. The ones we used are Thomas train wind up by TOMY (Japanese toy manufacturer)

http://wrocket.hampson.net.au/?p=337

Just depends what you have available where you are. These TOMY ones have a regulator in them, so that when you remove the wheels they still wind down at the same speed. Some of the cheaper ones if you remove the feet / fins / wheels of the toy they just spin down in less than 1 second as there is no work being done against the spring mechanism.

These TOMY ones are good for about 10-12 seconds

-todd-


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Re: Dual Parachute Deploy Modular Nosecone

Post by Spaceman Spiff » Wed Oct 08, 2008 10:07 am

thampson wrote:thanks graveyard. I have pics of the tomy timers in their packages on this URL on our blog. The ones we used are Thomas train wind up by TOMY (Japanese toy manufacturer)

http://wrocket.hampson.net.au/?p=337

Just depends what you have available where you are. These TOMY ones have a regulator in them, so that when you remove the wheels they still wind down at the same speed. Some of the cheaper ones if you remove the feet / fins / wheels of the toy they just spin down in less than 1 second as there is no work being done against the spring mechanism.

These TOMY ones are good for about 10-12 seconds

-todd-
Is there a way to tell if a timer toy has a regulator or not without opening it up or taking it apart? You can find them in gift shops all over the place so if there was a way to test them non destructively then I would pick some up next time I see some.


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Re: Dual Parachute Deploy Modular Nosecone

Post by Cloud Dancers » Wed Oct 08, 2008 12:15 pm

Isn't the regulator you mention really just a flywheel and some reducing gears?

That is probably what to look for.


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Re: Dual Parachute Deploy Modular Nosecone

Post by thampson » Thu Oct 09, 2008 11:58 am

I dont think you can tell without opening it. Although they do have a distinct sound - pushing all those gears, very noisy. When I did take one apart it did have quite a few gears inside, probably about 6. I imagine turning all these gears alone puts load on the coil inside.

I originally used ones I found in a $2 shop, they were like swimmer toys. But as soon as you take the load of the spring (ie: cut the tail off) they are no good. The only ones so far I have seen that work as intended when you take the load off them (or wheels in this case) is the TOMY ones. TOMY exports all around the world. Look here

http://www.tomy.com/top_img/distribution.htm

For your country and the name of the distributor and give them a call or email to see where you can get their "wind up" Thomas trains. You can email them the pics from here to tell them what you are after. They cost about A$3 here each

http://wrocket.hampson.net.au/?p=337

-todd-
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Re: Dual Parachute Deploy Modular Nosecone

Post by Cloud Dancers » Thu Oct 09, 2008 12:18 pm

Thanks for the info Todd. I will check those out.

In the US these timers can be frequently found in McDonalds "Happy Meals".

I think that most of the "walking" ones have the "gears" in them so that they walk at a reasonable speed. Rolling toys may be the ones without. Relying on the wheel friction on the ground to resist the spring.

Maybe we should have a "supplier list" here.


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Re: Dual Parachute Deploy Modular Nosecone

Post by thampson » Mon Oct 13, 2008 7:20 am

Just wanted to update the post. We tested this config this wekend, but had a pressure leak at 80psi. We currently dont have an abort system on the launcher so for safteys sake we launched. It lawn darted unfortunately.

I have just about rebuilt the modules with a slightly different design using a dummy PPNC module and a main chute module. I am alos presently adding a launch abort valve to the launcher.

I will update again once we go for another dual parachute launch.

-todd-
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Re: Dual Parachute Deploy Modular Nosecone

Post by thampson » Tue Oct 21, 2008 8:01 am

Hi all,

we had a launch day on this past sunday to test out the dual parachute deploy. we had some limited success but ended up crashing the wrocket (twice).

The first launch of the day at 110psi saw the main only deploy, issue on the drogue release timer was the elastic got stuck. We will have to redesign this section as it needs to be more reliable.

Second launch we tried to abort due to wind but the launcher broke before we could get to the abort valve and we ended up with a cruise missile. Some damage but was fixed.

Third launch was a crashdown with no deploys and to make matters worse the foot pump broke at 100psi.

I think we are making progress .. slowly ... for safeties sake we will make a launch rail for the next launch day, our wrocket with both modules and the big PPNC dummy nosecone is 100cm tall and we are only going to add to it ... :) It did look good before we went :)

Pulling the parts apart afterwards both chute modules are damaged and the nosecone is a write off but easily replaced, one pressure bottle is damaged but the fins and bottom bottle are ok ...

We will also look at some 12V pumps .. any suggestions are welcomed ..

There is a write up and a video of the chute release on our website http://wrocket.hampson.net.au


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Re: Dual Parachute Deploy Modular Nosecone

Post by Spaceman Spiff » Tue Oct 21, 2008 8:57 am

Hi Todd!

Sorry about your mishaps but glad to hear the damage was not too severe and you were able to learn a lot from the experience. I can't help but be reminded of the early experiments of guys like Robert Goddard and the Wright Brothers as they developed the groundwork for their successes.

As for pumps: My best recommendation is to find one with good ventilation. Ones with a cooling fan and a lot of metal cooling fins on the cylinder are the best. The failure of most pumps is due to overheating, so the cooler it runs the better.


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Re: Dual Parachute Deploy Modular Nosecone

Post by thampson » Wed Oct 22, 2008 7:40 am

Thanks Spaceman :) .. Im looking at the different options available for the pump. Appreciate the advice on the cooling, seems like this is a common cause of failure, so I will pay close attention to that ..

cya
-todd-


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Re: Dual Parachute Deploy Modular Nosecone

Post by Spaceman Spiff » Wed Oct 22, 2008 10:16 am

thampson wrote:Thanks Spaceman :) .. Im looking at the different options available for the pump. Appreciate the advice on the cooling, seems like this is a common cause of failure, so I will pay close attention to that ..

cya
-todd-
Todd,

I have discovered that the compressors that run on DC from your car seems to almost all work at higher pressures than the kind that use AC power from a wall outlet. I suggest you look at DC powered compressors and get a small battery like one from a motorcycle or lawnmower to power it when you're out launching.

Also, don't get greedy with the pressure. USWR did a report some time ago showing that these small pumps break down if you try and use them at their rated pressure. They made a video with a compressor catching on fire trying to get to the pressure rated on the box. Always assume the compressor and only reach between 2/3 and 3/4 of the rating.


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Re: Dual Parachute Deploy Modular Nosecone

Post by Tim Chen » Wed Oct 22, 2008 12:52 pm

Here is the article that Spaceman is talking about

http://www.uswaterrockets.com/business/ ... ory_01.htm


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