wiki/ news/ 2009-04-19 - Drop test of recovery system, with a tad bit more success.


Once again, it was a beautiful day to drop stuff out of airplanes!

And once again, a bunch of us headed out to a farm in western Oregon to test the recovery system. With the land-owner's permission, we dropped the recovery system (nosecone, separation ring, parachute system, recovery module) and a 9 lb. weight to make sure we had at least 20 lbs. of force on the various parachutes.

But, unlike last time, this time everything worked! The timers fired the nose cone separation ring, the drogue deployed, the line cutters fired, the main deployed, and the two systems came down to a fairly gentle landing. This concludes the "ground" tests our recovery system: the next test is to launch it!

Prep work

The day (and night) before, we rebuilt the the flight computer using some PerfectFlight microTimer2 timers. They seemed solid, although there were many aspects of the timers which we didn't like:, including the non-0.1" hole spacing for connectors, and the scary 15 mA (not 3mA!) continuity detection. But they worked!

We used Nathan's estimation of drop time's for the timers:

Event Elapsed time (s) Height (Agl, ft)
Drop 0 2600
Drogue 8.3 1500
Main 17.5 750

And we thoroughly tested the system: with LEDs, with igniters, with doubled igniters. With one possible anomaly, it worked solidly.

Flight computer testing.

Some Pretty Pictures and Movies

We got a few shots from the plane:

Parachutes from the plane's point of view.
Another aerial shot.

And a lot of shots of the system after recovery:

Nosecone and drogue parachute.
Recovery module and main parachute.
Another view of the module and main chute.
The flight computer worked (!)

And a few shots for noting the state of the system when we found it:

Inside the module; line still in line cutter.
Check out Dan's message in the NSR :)
Removed line cutter piece (~ 2 lbs of force).
Inside the module without the line.
Many of the lines were quite twisted up.

Here are some high-speed (300fps) videos of today's test:

And finally, here is a normal-speed video (20 MB) of the drop test.

No (useful) data for us

We all went out for lunch afterwards, at which point Dave got to dump the data from the LPC2148 w/SCP1000 logging board. Disappointingly, the pressure sensor board didn't seem to work: Just like before, something happened at it stopped recording before it left the plane. We're hypothesizing that something happened with the SCP1000 and it stopped asserting the DRDY line, which would freeze the LPC. This definitely needs more investigation if we plan on using the SCP1000. Here's the raw data from the LPC board, and here's the spreadsheet with processing and graphs. And for your instant gratification, here are a the graphs:

Graph of pressure data.
Zoom of the last few points, with anamolous points.