3 Comments »

RSS feed for comments on this post. TrackBack URI

1. Michael, building a rocket and using your iPhone to collect and broadcast data about the launch is not very slacker-like. It’s far too cool. Fun stuff.

   I liked the idea that you planned to use the data to be able to track down the iPhone like a geocache. But it sounds like you don’t have data for the last part of the descent.

   Keep us posted on your progress.

   Comment by bethkatz17582 — November 10, 2008 #

2. Great stuff!

   The iPhone 3G uses the LIS331DL accelerometer which has a user configurable range of ±2g or ±8g. The FS (“full scale”) measurement range in Table 3 of the LIS331DL datasheet shows that when the FS bit is set to 0, the “typical” range is ± 2.3g which looks pretty much like where your accelerations maxxed out. So you basically have no idea what the true acceleration was during the ascent phase once it got beyond +2.3g. The good news is that this implies your iPhone went higher than the altitude you get just integrating the vertical acceleration curve twice.

   Cheers,
   Doug

   Comment by dougwelch — November 11, 2008 #

3. Without regard to what the accelerometer said, the GPS should have given you the correct altitude. If what you want to do is retrieve the iPhone, then have it send the GPS right after apogee, then maybe just before landing. You can get these points from the GPS altitude. You don’t have to stream the data in real time. The iPhone has enough memory for a few data points.

   I would call this project an “iPhone killer app”. Of course, yours survived. What they say is “if at first you don’t succeed, then sky diving is not for you.”

   Comment by suitti — November 11, 2008 #

Leave a comment

You must be logged in to post a comment.