Doug Conner attended Maker Faire in San Mateo, Calif., and was impressed by a compressed-air rocket demonstration. These are not actual rockets -- they're projectiles -- but he was sufficiently inspired to go home and make his own PVC-based rocket and launcher. He started sending rockets 200 to 300 feet high from his backyard. Then a brainstorm hit. What if you could watch the flight from the rocket's point of view?
Conner decided to strap a video camera on to the rocket. This required calculations to accommodate the additional weight of the camera. He increased the body diameter and length of the rocket and sent it up with a live camera shot of the trip.
Doug Conner calculated that he could achieve approximately the same flight with the extra weight of a camera if he increased the body diameter and length.
Doug uses a launch pressure of 45psi for the flights, which typically last 7.1-7.4 seconds.
I feel that the article implies that Mr. Conner CREATED the idea of placing a camera on his rocket. Nothing is further from the truth than that. A quote from the article: "Then a brainstorm hit. What if you could watch the flight from the rocket's point of view?". In the 1960's, the Estes Model Rocket Company sold two cameras for this purpose. One, a still-shot was called "Camroc", and the other a motion-picture camera, "Cineroc". The Germans during World War II deployed launch cameras on their V2 rockets and Robert Goddard did it way before that.
I only mention this because of my objection to the way the article was written, not to detract from anything Mr. Conner did. I believe that any young person interested in rocketry might not be aware of the history of rocket cams and assume something otherwise.
Actually mine was a two stage rocket. I never thought of using soda, but I can see where it would work better and I can imagine the sticky mess. Some times I would manually release the top rocket and leave the base rocket in place. I do not remember why, only that I did it.
Yes, I had the single stage air over water rocket as a kid too! I would pump it up as much as I could to get it to go ever higher and higher. I also varied the water level over and below the water level mark on the translucent rocket body, trying to see if more air or more water would take it to higher altitude. Finally in an epiphany I tried 7Up! It sent the rocket to record heights. Unfortunately at the launch pad I was a wet sticky mess and my mother began to suspect the sudden high consumption rate and my sudden interest in her favorite summer beverage. My rocket fuel was rationed afterward... Great memories, thank you !
WARNING: Find and use a valve designed for handling air pressure. I was an irrigation valve engineer for 19 years and PVC valves rated for 150 psi water pressure are not safe handling air pressure. The faster parts motions associated with air induce higher part impact stresses than with water. The in-line valve is better, but there was a lawsuit we had where someone shot their eye out using air pressure to blow-out and winterize an Antisiphon style irrigation valve. And then there will be those that wan to go launch higher and keep creeping up the launch pressure. Wear your safty glasses!
As a kid I had a rocket that was partially filled with water and then attached to a hand operated air pump. As the air was pumped into the rocket body it passed through the water and built up pressure. When the rocket was released from the pump, it expelled the water which forced the rocket upwards. There was even a second stage that mounted on top of the first and was secured with some sort of pressure valve. When the first stage was emptied, the valve would release the second stage. It has probably been 50-55 years ago and i do not remember how high it went, but it was enough that the projectiles would land several houses one way or the other.
I was the only kid on the block that had one and I never saw another, so I do not know how popular they were. Today they would probably be outlawed because the projectile did have some weight and I am sure there is a lawsuit there somewhere. It finally cracked on landing and no glue that I could find would return it to its air/water tight state.
What a cool and innovative way to launch rockets. In reviewing the design of the launcher circuit schematic diagram, as a phase 2 project, have a digital timer switch the solenoid valve. With the timer, you can give your compressed air rocket an automatic controlled launch with a real count down sequence. Great project and article!
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