Water Rocket Car MkIX – Nighttime Launch

Before the details of the night time launch, a few modifications to the steering were performed. These included

– Reconfiguring the transmitter to reduce the travel distance of the servo, both left and right
– Adding a physical limitation to stop the front wheels from being able to turn to full lock

The overall effect was that the steering is not as sensitive. Here is a pic

Steering Update - stoppers

Steering Update - stoppers

A 7mm nozzle reducer disc was added to the nozzle and tested up to 60psi prior to launch. We also used for this launch 5 x 3L bottles of water for the weights on the launcher (approx 15kg)

Night Time Launch
One good thing about the new test track we have is that it is lit at night. So after making the alterations I decided to go by myself and give them a test. Here is a pic of the track. Its lit well enough to see the car but not really well enough for video. Here are a couple of pics,the light was a little better than the pic shows.

Test Track - lit at night

Test Track - lit at night

Water Rocket Car and Launcher at night

Water Rocket Car and Launcher at night

Launch 1 – 1000ml (foam) & 100psi
Unfortunately when the car was pressurized to 100psi it started to leak out of the thread side of the nozzle. We went ahead with the launch anyway and the rocket car went fine, distance about 77m. However trying to fix the leak on site just wasn’t happening, tried extra teflon tape, closing the nozzle tighter with metal grips … it still leaked. So we aborted that launch and just removed the reducing nozzle and pressurized again. No leaks ..

Launch 2 – 1000ml (foam) & 120psi
This launch was at 120psi uphill and the car went very well, it actually stayed within 1 cars lane width the whole way. I measured out at 107m by foot (no long measuring tape yet so just a personal record at the moment)

The launcher and equipment was moved up to the other end for a reverse run to see  if we could beat that distance with the slight downhill run

Launch 3 – 1500ml (foam) & 120psi
We added a bit more water this time and pressurized to 120psi again. The launch was pretty spectacular with a big looping fishtail going down the course. The rooster tail from the rocket spray made it hard to see where it was going at night so it may have been driver error that caused the fishtail :( … The distance was good though. 110m

Launch 4 – 1500ml (foam) & 120psi
Its a little hard to tell exactly what pressure this one launched at. I think it was 120psi but not sure. Halfway through pressurizing I heard the unmistakable click of a large relay going off … follow not long afterwards by the floodlights on the test track also going off … hmmm .. standing in the dark … thoughts of aborting were the way to go until I realized I could just turn the car around, point it down the track and put on the high beams … So did that and with the track lit pretty well, launched.

Again a big long looping fishtail down the course, made even harder to see with the rooster tail from the exhaust spray being lit up my the high beams headlights …. The car made it out to 98m which was ok considering …. packed up the gear and headed home.

We need to work on the leak with the reduced diameter nozzle to get the best out of this car. This should tame the fishtail


This entry was posted on Friday, October 23rd, 2009 at 6:22 pm and is filed under Launch Days. 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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