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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.

Thampson WR-car record

Discussions about water rocket powered cars, sleds or boats.
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Re: Thampson WR-car record

Post by RebelRockets » Sun Nov 07, 2010 1:18 pm

Just go around in circles.
George,

That reminds me of the ancient times ( my childhood :( ) before R/C electronics when gas powered model planes were flown around in circles on control lines held by the operator and model cars ran around in circles tethered to a pylon.

Even if that doesn't become allowable for a record, tethering the car to a pylon during testing could save the car from major collision damage.

Dennis



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Re: Thampson WR-car record

Post by RaZias » Sun Nov 07, 2010 3:59 pm

It seems making circles would be the answear.

A drag road and a salt bed aren´t easy for everyone, even the permission in an airport is not easy.

If I was in my country of origin (Portugal) I could make a road in the montain where I used to make montain biking, I used to do that to creat new trails for biking.

There are also the stadiums, that have a run area around the football field, for doing the 100m run...may a WR-car could make 2 laps in that area...but I don´t know how I could get permission to do that...

Just remember, finding a High-way in construction is the holy-grail for this.


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Re: Thampson WR-car record

Post by RaZias » Sun Nov 07, 2010 4:11 pm

I just remembered from another problem, if you want to go in straigh line for 500m is the RC range capable of those distances ? SC:


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Re: Thampson WR-car record

Post by thampson » Mon Nov 08, 2010 2:03 am

Last time I looked at range on the r/c transmitters, the good ones used for r/c planes had a range up to 800m which would be more than enough as long as you still had line of sight. It would also help if the antenna was vertical I imagine. Another option is to Rollerblade after it holding the remote to reduce the range needed.

We have tested our transmitter range to around 200m and it was still working fine, we just ran out of line of sight at that point and couldn't hear each other shouting to turn the steering on the transmitter anymore.

The idea of a highway under construction is a good one to run the car. There is a 20 year project going on here to upgrade the pacific highway (Sydney to Brisbane ~ 1000km) with dual carriageway, km's and km's of nice flat white concrete :)

They do it in 20 - 30km sections typically so that might be an option as well. The road workers never work on the weekends anyway :)

-todd-


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Re: Thampson WR-car record

Post by thampson » Fri Nov 12, 2010 11:13 am

Hi Lisa,

Do you have a timeframe for the next (hopefully last) version of the water rocket car rules ?

thanks
-todd-


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Re: Thampson WR-car record

Post by WRA2 » Fri Nov 12, 2010 9:39 pm

thampson wrote:Hi Lisa,

Do you have a timeframe for the next (hopefully last) version of the water rocket car rules ?

thanks
-todd-
The timeframe should go as follows:

I will post a new draft within the next week. (I have been waiting for the discussion to slow before I make a draft. Then we can debug and have the final release by months end. Ratification by a membership vote will follow during December with a formal start of the competition starting on the 1st of January 2011. WO:

Do you have any photos of your WR dragster in action that you could contribute to use to demonstrate a WR dragster on the WRA2 competitions page?


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Re: Thampson WR-car record

Post by U.S. Water Rockets1 » Sat Nov 13, 2010 9:38 pm

RaZias wrote:USWR,

I know that it´s almost impossible to turn the rocket unless you make very open turns...even so it´s very hard to make it, just imagine the speed of it.

But once again, how do past from a 500m record ?

For WR the sky is the limit, but for the WR-cars 500m would be a serious limit.
It seems very unlikely that a water rocket car would go 500 meters. The friction of the wheels should slow it down well short of that. It seems like an issue that we probably don't have to worry about. At least not right away. As someone gets a water rocket car to get closer to 500m, we could assume that they have worked out the location to go that far.


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Re: Thampson WR-car record

Post by thampson » Sun Nov 14, 2010 8:48 am

I dont think long stretches of straight asphalt are going to be as hard to find as we think.

I spent an hour on Google Earth looking over industrial areas in Sydney today and have 11 potential sites. All of them are straight and over 200m long with most in the 300m and 400m range. I used Google Earth Street view to see if they were close to level and most look ok. I will be doing some reconnaissance of the sites in the next week to check them out.

As they are industrial areas and are mostly dead end roads, I should be able to find 1 or 2 that are pretty deserted to use on an early sunday morning or late sunday afternoon launch.

I have uploaded them to Google maps so I can navigate to them using google maps on my phone, so if anyone is interested here are the sites
http://maps.google.com/maps/ms?hl=en&ie ... e68e44527b

USWaterrockets is right about 500m, thats a long long way, I would think a water rocket car would need multiple stages to get that far ;)

-todd-


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Re: Thampson WR-car record

Post by RaZias » Sun Nov 14, 2010 12:48 pm

Your rocket at 140 psi made like 150 meters (i think), so a 300 psi would make 300 meters (using a small nozzle to not haste all the power at the begining).

Getting a 300 psi in a rocket with the doble of your WR-car volume it could go far than 300 meters.

I know that I am making linear extra-polations but that is the best estimation avaiable.


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Re: Thampson WR-car record

Post by WRA2 » Thu Nov 18, 2010 11:19 pm

I have been working on the next draft and found a possible loophole. DOH: We need to define a minimum size for the wire mesh cage that will protect from an exploding pressure vessel. We need minimum size for the "grid squares in the mesh and also a minimum size for the wire strands the mesh is constructed from. If we do not have a minimum we could have a competitor :twisted: try to use ordinary window screen for the cage BO: which will not be sufficient protection.


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Re: Thampson WR-car record

Post by thampson » Sat Nov 20, 2010 8:08 am

Lisa,

As a guide, this is the wire that I am using.

Aviary Wire
- Grid Squares --> 6.5mm x 6.5mm (1/4" square)
- Wire Thickness --> 0.63mm (0.024")
- Grids are welded
aviary-mesh.jpg
An alternative is Bird Netting (Chicken wire)

Chicken wire is typically
- Hex Shaped grid available in 1.3cm (1/2"), 2.5cm (1") and 5cm (2")
- Wire thickness 0.56mm (0.022" ), 0.9mm (0.035") and 1.0mm (0.039") respectively
- Hex shapes are twisted
chicken-wire.jpg
I think the grid square we should apply is 10mm x 10mm. This means if you want to use chicken wire, you just need to do a second wrap and overlap the hex patterns. The 0.63mm wire thickness I am using seems plenty thick enough although the 0.56mm chicken wire would probably be the minimum I would think.

Hope this provides the clarification we need to close the loophole :)

-todd-
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Re: Thampson WR-car record

Post by WRA2 » Sun Nov 21, 2010 9:42 pm

The new draft has been released for the Water Rocket Dragster Competition Rules.

It is ready to be reviewed.


http://www.wra2.org/WRA2_Dragster_Rules.php


My thought for the speed competition would be like dragster time trials where the competitors will time the dragster on a fixed distance course. Everyone uses the same distance and can go head to head based on ET (Elapsed Time) Just like they do when racing cars.


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Re: Thampson WR-car record

Post by thampson » Mon Nov 22, 2010 9:53 am

> Do you have any photos of your WR dragster in action that you could contribute to use to demonstrate a WR dragster on the WRA2 competitions page?

Lisa,
Sorry I didnt reply to this. Id be more than happy to supply a picture for the competitions page. I will look through my pics to find a good one:)

-todd-


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Re: Thampson WR-car record

Post by WRA2 » Mon Nov 22, 2010 8:40 pm

thampson wrote:> Do you have any photos of your WR dragster in action that you could contribute to use to demonstrate a WR dragster on the WRA2 competitions page?

Lisa,
Sorry I didnt reply to this. Id be more than happy to supply a picture for the competitions page. I will look through my pics to find a good one:)

-todd-
Thanks, It is WRA2 tradition to have teams contribute photos for the website.


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Re: Thampson WR-car record

Post by WRA2 » Tue Dec 07, 2010 5:59 pm

Bump:

We will be holding a vote on adoption of the Water Rocket Dragster Rules soon. Are there any more suggestions or bugs that need working on.

The draft can be found at:

http://www.wra2.org/WRA2_Dragster_Rules.php


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