Water Rocket Mk VI – More testing

Robinson Coupling Update

We had a few test runs on the front driveway at 60psi but there were leaks, so back onto the workbench to strengthen the coupling on on MkVI. To be truthful, we should have had the additional washers in the robinson coupling configuration in the first place, but previously with 1.25L bottles and 130psi max we didnt see any leaks without the metal washers. Due to the increased volume and pressures we are working at now, we realize these are indeed needed.

We have inserted another metal washer at on the bottle cap side of the coupling so now we have one behind the nut at each end as described by the diagram below.

robinson coupling exploded diagram

Robinson coupling exploded diagram

The MkVI with the 2 x 2.25L bottles and above coupling configuration was hydrostatic tested at 140psi for 1 minute without any leaks. So its all ready to go for next weekends test at our new launch / track site.

Initial Test Runs – low pressure (100psi)

We have performed some initial test runs at 100psi (due to space limits at home driveway) to see how MkVI performed. No video unfortunately as it was just adhoc testing to empty the bottles after the hydrostatic tests. Initial  observations are

– Thrust lasts a lot longer than the 1 bottle config
– During pressurization some water is forced into the second bottle
– All the water is not expelled from the second bottle after launch
– The 100psi pressure launched MKVI to a distance of 38m which is similar distance to 1 bottle at 140psi.

Our driveway is long but narrow, so we really threaded the needle to get this distance which means directional stability is good.

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This entry was posted on Tuesday, August 4th, 2009 at 12:05 am 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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