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Video from a Google NexusOne smartphone with specially programmed Android apps, installed aboard James Dougherty's Intimidator-5 on a CTI N4100 load. Launch from Black Rock Playa on 24-July-2010 thanks to Maverick Civilian Space Foundation.
I'm curious about the launch, launch vehicle, and flight data. Can anybody tell us the story that goes with all this spinning and tumbling?
Where was the launch? What class of rocket was this? Was there an air traffic TFR for it? Was it part of an amateur launch day, and if so, where are the crowds? What was the final altitude? What was the payload mass? Was there any concern for thermal swings? Was the movie app triggered by a phone call? Was the camera deliberately aimed toward the parachute, or did it just turn out that way? Inquiring minds need to know.
replied to comment from Papa
| July 29, 2010 3:00 PM
| Reply
Hi Papa...
Some of the questions you're asking are answered already in the video description, but you have some other good ones.
Not all rockets will spin and tumble, but we have a few good guesses with what's going on with James's Intimidator rocket. In brief, the payload did was not balanced and the center of gravity was not precisely the physical center of the rocket, which introduced some wobble.
Additionally, the motor used to lift the rocket was a powerful Cesaroni N4100 scale solid rocket engine, which is 41 inches tall, 4 inches wide, and a 4000 pound per second total impulse lifting an 80 pound rocket!!!
The exhaust coming out the bottom of that rocket is a blazing tornado of fire and we did not have the control system to stop it from spinning. You can see Steve Jurvetson's image of the rocket at lift off at the MakeZine blog which describes some more detail.
Your question about thermal swings can be answered in my twitter post a few weeks back where we thermo-cycled the phones in a vacuum to make sure they'd handle the space environment. This rocket only went up to 30k feet and the temperature swings are well within the phone manufacturer's tolerances.
Lastly, the parachute being in the video was PURE LUCK as the hole in the rocket was randomly drilled (and you can see how it's slightly off center by looking closely at the top left & right corners of the video). The video application was manually started just prior to installing the phone into the rocket.
Thanks, Matthew. I didn't mean to be critical of spinning tumbling rockets. I mainly don't know anything about them.
I figured spin was either designed-in, or not designed-out, as you said. I'd guess few if any non-commercial rockets are attitude-controlled, so no criticism there, either.
I didn't think to pull up the source page on YouTube and look there. That was helpful, as were the MakeZine and Wired articles.
I guess what I was thinking is that the video is data "looking out", but half or more of the story is missing -- data "looking in". I was looking for a description of what the rocket and payload were doing that corresponds to what we see in the video. Thanks for your answers, and for the YouTube paragraphs and the articles. For example, I had no idea it was reaching Mach 2.4 and 30,000 ft agl. That kind of information helps people get excited about what you're doing.
Maybe there's a way to despin the video, yielding a panoramic view that changes vs. altitude. That means developing an attitude model for each frame of the video, which may not be easy. Then you could map the horizon +/-30 deg onto the rectangle of the screen, and populate/repaint portions of that rectangle each time the camera sweeps across it.
Maybe in the future there's a way to do that intentionally, i.e. to exploit the spin. Could you fly a mini attitude sensor to assist with that?
I think I'm motion sick.