Water Rocket Car MkVI

After our latest successful tests of having the wrocket car going straight, its time to work on increasing the speed. There are two ways to do this

– reduce weight
– increase thrust

We decided to work on both ….. some design work has started on a new lighter longer bodied wrocket car. Hopefully this will see the light of day in a few weeks. While this is in the works, we have added another 2.5L bottle to the existing wrocket car to increase thrust on the existing car …..  and here she is

2 Bottle Wrocket Car

2 Bottle Wrocket Car

The modifications we have made are as follows

– Added second 2.25L bottle with an enhanced Robinson coupling
– Changed the position of the bike computer
– Installed a smaller stopper between the first and second bottles
– Used stronger cable ties to hold the wrocket down
– Added a nosecone to reduce aerodynamic drag
– Moved the front wheel angle supports to allow space for the second bottle

The enhanced robinson coupling uses an additional washer to assist in sealing a bigger area between the bottles.

Stronger Robinson Coupling

Stronger Robinson Coupling

Robinson Coupling

Robinson Coupling

The bottle connection is made as per our previous howto post showing how to make these couplings except for an additional washer. We tested the coupling up to 60psi without any leaks. We will do a hydrostatic test up to 140psi to see if the coupling will hold the intended launch pressure.

The bike computer has just been moved to a vacant spot to get out of the way for the second bottle. The nosecone was made from the top section of a 2.25L bottle with a half ping pong ball glued (with PL Premium) in place of the spout.

Front View

Front View

A smaller stopper is screwed in place betweeen the bottles. This is used to arrest the forward motion of the bottles on the wrocket itself. The base of the rear bottle on launch hits up against this stopper and the cable ties then hold it in place.

New smaller stopper

New smaller stopper

Here is a view through the nozzle showing the coupling. Just visible in the centre of the coupling hole is the molded join of the bottom of the far bottle. Click on the pic below for a larger view.

Nozzle View

Nozzle View

It will be interesting to see how the water and air mix going from one bottle to another in a horizontal position as well as how much water is left in both bottles. We will do some tests but have a solution in mind to keep the first bottle full of water and leave the second for air only .. we will see if we need it or not after or next test day.

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This entry was posted on Tuesday, July 28th, 2009 at 11:33 pm and is filed under Development. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

 
 

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