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- Aug 27, 2011
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Well, I think design is good but this is the first failure I've had of the thrust restrictor bands (the equivalent of a thrust ring on standard rockets.)
The motor is held in place with two rubber bands, which both block forward motion and hold it in place in back. There are foam centering "squares" (again, equivalent of centering rings in a standard rocket) that hold the motor in place from side to side.
As far as I can tell, the bands broke at ignition, and the engine slid forward into the rocket body. In this case, a rocket body made only of 1/8" balsa. In combination with a demonstration of the Krushnic effect, the rocket didn't get much altitude, kind of a shallow St. Louis Arch. On board video is pretty dramatic, however. There wasn't much to salvage.
This is a larger diameter than I have used with previous rubber band retention models, and I think the bands were just stretched too tight. Will have to go with larger bands next time. Again, this is the first failure I've had with this type of retention.
[video=youtube;Xp2x_vlEMGo]https://www.youtube.com/watch?v=Xp2x_vlEMGo&feature=youtu.be[/video]
https://www.youtube.com/watch?v=jzgWUNt5NhI
[video=youtube;jzgWUNt5NhI]https://www.youtube.com/watch?v=jzgWUNt5NhI[/video]
The motor is held in place with two rubber bands, which both block forward motion and hold it in place in back. There are foam centering "squares" (again, equivalent of centering rings in a standard rocket) that hold the motor in place from side to side.
As far as I can tell, the bands broke at ignition, and the engine slid forward into the rocket body. In this case, a rocket body made only of 1/8" balsa. In combination with a demonstration of the Krushnic effect, the rocket didn't get much altitude, kind of a shallow St. Louis Arch. On board video is pretty dramatic, however. There wasn't much to salvage.
This is a larger diameter than I have used with previous rubber band retention models, and I think the bands were just stretched too tight. Will have to go with larger bands next time. Again, this is the first failure I've had with this type of retention.
[video=youtube;Xp2x_vlEMGo]https://www.youtube.com/watch?v=Xp2x_vlEMGo&feature=youtu.be[/video]
https://www.youtube.com/watch?v=jzgWUNt5NhI
[video=youtube;jzgWUNt5NhI]https://www.youtube.com/watch?v=jzgWUNt5NhI[/video]
