Weightlessness

Summary
NASA's Weightless Wonder simulates zero-gravity by following a parabolic trajectory that enables the plane–and everything inside of it–to fall together with the normal gravitational acceleration (9.8 m/s^2). Because of that, when you drop a ball inside the plane, it will fall at the same rate as the floor, so it will appear to float. For more detail, look find below a copy of Professor Ed Thomas's weightlessness presentation.

Acceleration Data
Collectively, we were all weightless for approximately 45 minutes, 11.3 minutes per flight.  We were in the air for a total of 4 hours during the flight week. So far we have the acceleration data for 2.5 hours of that, and we're actively seeking the rest. Here you'll find a description of the data and how you can use it. Team Isotopes and Team Philly recorded some accelerometer data from the Wednesday and Thursday flights.  As we accumulate it from various sources, we will also be posting the accelerometer data from our flights below. If you have any questions, feel free to email Stephanie Wissel at swissel@pppl.gov

Wednesday, July 27, 2011
The data from Wednesday was taken with an on board accelerometer (ADXL335 from SparkFun Electronics) that was calibrated prior to the flight. Unfortunately, Team Philly's experiment was shut down mid-way through the flight, so we only have acceleration data from the first 1600 seconds or so, including the first 10 parabolas.

What you can see is that the flight was considerably smoother during the zero-g portions than the 1.8-g portions and that the plane leveled off after completing 5 parabolas.  Acceleration data was recorded 1000 times per second, and the complete data file is: acceleration_74.lvm (192.5 Mb).

That's a pretty big file, so only use it if you need to know the precise acceleration at each millisecond during the flight. If instead, you only need acceleration data recorded every tenth of a second, use the file: acceleration_74_10Hz.csv; every 1/2-second, use acceleration_74_2Hz.csv; or once every second, acceleration_74_1Hz.csv.  Those files are available on the ftp site and in the files below.  We also broke the file up into smaller segments in case you want to look at the large file in smaller chunks.

Thursday, July 28, 2011 – Morning Flight
The data from the Thursday flights were recorded with the plane's onboard accelerometer, which reports out signals in Volts instead of g's. If you plot the raw signal versus time, it looks like this:
You can clearly see the 1-g portions of the flight: while everyone is setting up (0-500 s) and during two level-offs (~1300–1700 s and ~2500–2700 s). We also know that the plane oscillated between 0-g and 1.8-g, so we should be able to calibrate the data.  The first 500 s are fairly steady and if we figure out the average value of the voltages during that time, then we can convert from volts to g-s.  

Above you can see that for the first 500 s, the average value is 3.275 +- 0.1229 V. So if you divide the raw signal by 3.275 V per g, they you can figure out what the acceleration was during the flight. Also, check out the lunar and martian parabolas at the end.

As before, the acceleration data was recorded 1000 times per second, and the complete data file is: acceleration_6.lvm (435 Mb).

That's a pretty big file, so only use it if you need to know the precise acceleration at each millisecond during the flight. If instead, you only need acceleration data recorded every tenth of a second, use the file: acceleration_6_10Hz.csv; every 1/2-second, use acceleration_6_2Hz.csv; or once every second, acceleration_6_1Hz.csv.  Those files are available on the ftp site and in the files below.  We also broke the file up into smaller segments in case you want to look at the large file in smaller chunks.

Thursday, July 28, 2011 – Afternoon Flight
If we process the afternoon flight's data in the same way, we can see that the afternoon flight was a little choppier than the morning flight.


All the same, the data files are available both on the ftp site and below. The acceleration data was recorded 1000 times per second, and the complete data file is: acceleration_0.lvm (431.5 Mb).

That's a pretty big file, so only use it if you need to know the precise acceleration at each millisecond during the flight. If instead, you only need acceleration data recorded every tenth of a second, use the file: acceleration_0_10Hz.csv; every 1/2-second, use acceleration_0_2Hz.csv; or once every second, acceleration_0_1Hz.csv.  Those files are available on the ftp site and in the files below.  We also broke the file up into smaller segments in case you want to look at the large file in smaller chunks.

File Summary
The acceleration data for Wednesday's and Thursday's flights have been uploaded.  The z-acceleration of the plane was recorded at 1 kHz (1000 times per second).  The complete (large) files are are available on the ftp site.  We recommend that you only use them if you need to:

Wednesday 192.5 Mbacceleration_74.lvm 
 Thursday – AM 435 Mbacceleration_6.lvm  
 Thursday – PM 431.5 Mbacceleration_0.lvm 

We processed these files to reduce their size, so if you only need to know the acceleration every tenth of a second, every half second or every second even, you should use these smaller files available below.  If however, you still want to use the acceleration data at the millisecond-sampling level, try using the data files broken up into 10-s chunks. The files are available on the ftp site, organized in folders named for each flight.  The files are named acceleration_no_startsec.00-endsec.00.csv.


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Professor Thomas's presentation on weightlessness   314k v. 1 Aug 17, 2011, 8:30 AM PPPL Clouds
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Z-Acceleration data for the morning flight on Thursday (07/28/2011). Data is recorded ten times per second.  3397k v. 3 Aug 18, 2011, 12:09 PM Unknown user
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  Dec 22, 2011, 9:25 AM PPPL Clouds
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Z-Acceleration data for the morning flight on Thursday (07/28/2011). Data is recorded each second.  340k v. 2 Aug 18, 2011, 12:09 PM Unknown user
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Z-Acceleration data for the morning flight on Thursday (07/28/2011). Data is recorded twice per second.  680k v. 2 Aug 18, 2011, 12:09 PM Unknown user
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Z-Acceleration data for the afternoon flight on Thursday (07/28/2011). Data is recorded ten times per second.  3217k v. 2 Aug 18, 2011, 12:16 PM Unknown user
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  Dec 22, 2011, 9:24 AM PPPL Clouds
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Z-Acceleration data for the afternoon flight on Thursday (07/28/2011). Data is recorded each second.  322k v. 2 Aug 18, 2011, 12:16 PM Unknown user
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Z-Acceleration data for the afternoon flight on Thursday (07/28/2011). Data is recorded two times per second.  643k v. 2 Aug 18, 2011, 12:16 PM Unknown user
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Z-Acceleration data for the Wednesday flight (07/27/2011) for the first 1600 seconds. Data is recorded ten times per second.   1452k v. 3 Aug 18, 2011, 12:04 PM Unknown user
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  Dec 22, 2011, 9:24 AM PPPL Clouds
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Z-Acceleration data for the Wednesday flight (07/27/2011) for the first 1600 seconds. Data is recorded once every second.  145k v. 2 Aug 18, 2011, 10:46 AM Unknown user
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Z-Acceleration data for the Wednesday flight (07/27/2011) for the first 1600 seconds. Data is recorded two times every second.  290k v. 2 Aug 18, 2011, 10:46 AM Unknown user
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