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November 25, 2011 

Water rocket sets new world record for number of cameras flown on a single flight.

This launch report documents a single flight which was launched on November 25, 2011 which set a new unofficial world record for the largest number of cameras ever flown on a Water Rocket. The new record was not the original purpose of the flight, but since we needed a number of cameras onboard to record the test data, we decided it would be fun to scrape together as many working cameras as we could, and place them at various locations on the rocket to try and make a new record. Another experiment which we were conducting on this launch was to test a type of lens called "Jelly Lens" on a Water Rocket for the first time.

We had recently made some software improvements to our free ServoChron 2 dual deploy servo timer software, and we wanted to capture video of the new software in operation to see if there were any issues that needed to be resolved. We also were anxious to obtain some showing the ServoChron working in conjunction with our newly invented Axial Parachute Deploy System, so that we would have a nice demonstration video to illustrate the systems in operation.

We decided to set up at Launch Site Beta with our reliable 15 liter B-2 Test rocket, and installed the cameras at various positions of interest along the rocket. We used our special "Boom Camera" to take an external view of the ServoChron and the Axial Deploy System, and we mounted an MD80 Camera on the boom near the root which would look up at the parachute deploying through a wide angle "Jelly Lens". These lenses are named as they are because they are made of a clear gel like material. These lenses are inexpensive "special effects" lenses which are sold for use with cell phone cameras to create special lense effects. In this case we were interested in using the lens to expend the depth of field of the MD80 camera so that the rocket and the background would both be in good focus. We had several of these lenses, so a second one was used to observe the LED's on the ServoChron from a few inches away inside the rocket.

We arrived at the launch area, and set up quickly, thanks to having prepared most of the rocket beforehand. We had even prefilled the rocket with water and used our removable launch tube system to keep the water from draining out of the rocket during transportation. Once the rocket was set up, all of the cameras were turned on and set to record video. We then quickly filled the rocket to 100PSI and launched the rocket at 2:01PM. We had been in a hurry to launch, because the temperature was 45 Degrees Fahrenheit (about 7 Degrees C), and we were fearful that the cold would shorten the battery life in the cameras, so we were trying to launch as quickly as possible. In our haste, we failed to notice that the rubber band of the Axial Deploy System had been working loose from the lobes that secure the nosecone to the rocket. All of the handling of the rocket during transportation must have moved the rubber band from the correct location. The rubber was likely stiffer due to the cold and had less friction to secure it as well.

The launch seemed to go off without any problems whatsoever, but almost instantly something seemed wrong because the blue plastic tip of the nosecone was seen separating from the rocket just above the launch area. At first it seemed like the tip of the nose had blown off or came loose because of the cold temperature, but then as the rocket slowed down near apogee, it was clear that the parachute had come out prematurely.

The rocket continued to climb to an apogee of nearly 250 feet, where it turned over and headed towards the ground with increasing speed, with the parachute somehow being dragged along without opening. It looked as if the rocket was doomed, when suddenly the parachute popped open and abruptly slowed the fall, causing the rocket to flip over 180 degrees into the upright orientation. The rocket then descended to make a soft landing in a patch of grass and snow.

At this point we were not quite sure what had happened to cause the early deploy, so we decided to pack up for the day and not conduct any further test launches until the cause of the deploy was determined. When we had returned to the shop, we were able to successfully download the video from all seven cameras and tanks to the number of onboard cameras we had employed, we were able to recreate the entire flight and the reason the rocket behaved the way it did.

The root cause of the failure was described above, where the rubber band had moved out of the correct position on the nosecone, which caused the nose to deploy thanks to the deceleration right after burnout.

The rapid deploy of the parachute at high speed cause the shroud lines to slip off the parachute rather than to unroll as usual, so the shroud lines ended up in a twisted wad which was wedged against the body of the rocket which was holding the parachute closed as the rocket ascended and began coming down.

After the rocket had reached apogee, it flipped over and because of the change in position, it gave the jammed parachute shroud lines some room to move. As the rocket picked up speed, the parachute became free enough to catch the air and then burst open about 100 feet above the ground.

The rocket was saved, and the cause of the near accident was simply human error, rather than a design error in the ServoChron or the Axial Deploy system.

In the end, the launch failed to obtain the exact video we were hoping for, but we were able to capture an unexpected event and obtain something a bit more interesting than just a demo flight video.

Here are some more highlights of the flight. As with all of our articles and tutorials, if you click on the thumbnail images, they will expand to a larger view and reveal extra commentary about the image:

If you want to see how to build our axial deploy system, click this link to go to the tutorial showing you step-by-step instructions:
USWR Axial Deploy System.

If you would like to build your own ServoChron 2 Dual Parachute Deploy Servo Timer, click this link for the complete tutorial.
USWR Axial Deploy System.

Other tutorials showing how to build a water rocket similar to our B-2 15 liter water rocket can be found at our tutorial menu:
USWR Tutorials Menu.


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