Each flight log entry usually represents a launch or test day, and describes the events that took place.
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Team Members at Event: GK and PK

We noticed that we forgot to link in the new underwater video on Day 25 so here it is: Day 25 Underwater launches. This video shows footage from underwater of launching a water rocket from a depth of 2m.

But now on to this weeks update .... In the last two weeks we have been rebuilding the Polaron rocket, increasing the capacity on the Acceleron rocket and building an updated launcher for it. We have also been working on building a thrust measurement test rig that hopefully will be able to provide us with information about the effectiveness of the experiments we are doing.

Events

• Acceleron's capacity has been increased by 6 L. A 2 litre bottle has been added to each segment of the booster. For this we needed to make three new couplings.
• The Acceleron launcher has been working very well with one exception: After every launch the o-rings in the launcher would get flushed out of their groove and had to be re-seated. This was quite annoying so we decided to create new nozzles for the rocket so that the o-rings sit on the nozzle rather than remain on the launcher.
• Because of Acceleron's higher capacity as well as higher weight, we increased the nozzle diameter to 10mm. As a result of the size increase and relocation of the o-rings we had to also make new nozzle seats in the launcher to accommodate the larger nozzles.
• The central aluminium pipe on the rocket has also been replaced with a longer one. The central pipe provides rigidity to the entire rocket and will function as a stable support for the second stage. At the moment only the dummy payload is attached.
• A second parachute was added to the rocket as its increased weight might be a little too much for the 900mm parachute. The secondary parachute is deployed the same way as Polaron III used to deploy its secondary parachute. Basically the primary line loops behind the secondary parachute and is pulled out when the primary chute opens.
• The detailed diagram at left shows the different components of the rocket as well as some dimensions.
• We wanted to fly the booster this weekend but unfortunately the weather was rainy with very strong winds so we decided to defer until the next favourable conditions.

Thrust Measurement Rig

• The thrust measurement rig is basically a balance with a rocket on one side and a calibrated kitchen scale on the other. As fellow water rocketeers have suggested in online forums we have first gone with the cheapest option before attempting to build a more sophisticated one. The scale dial is videotaped at 60 frames per second giving us basically 60 samples per second for the thrust measurement. After the experiments are complete, we will manually step through each of the frames and record the readings. This may sound a little tedious, but when you compare with how long it takes to do everything else associated with the experiment it is not really significant.
  
  Full details of the setup of the measurement rig will be posted with the next update.
• The electronic scales we have on hand do not change fast enough for our needs.