2 Today was the season opener for [Tripoli Colorado](http://tripolicolorado.org)
3 at their launch site on the buffalo ranch near Hartsel, Colorado. After huge
4 snowfalls along the front range of the mountains in the last few days, we were
5 a little tentative about going, but it turned out to be nearly perfect flying
6 conditions! There was apparently much less snow this week on the high plains
7 west of the front range, and by this morning the snow had almost entirely
8 disappeared, the skies were clear and blue, and the winds were calm except
9 for a few gusty bursts in the afternoon. This launch site is really something
10 special, at 8800 feet above mean sea level, in the middle of a huge area of
11 wide-open short grass prairie. We love flying there, and today the drive to
12 and from the launch site through the snow-covered Colorado Rockies was just
15 Son Robert and I flew three rockets today, including his
16 [LOC/Precision](http://shop.rocketsbymelissa.com)
17 [Lil Nuke](http://shop.rocketsbymelissa.com/product.sc?categoryId=-1&productId=114) with added
18 [payload section](http://shop.rocketsbymelissa.com/product.sc?categoryId=-1&productId=159) on an [Aerotech](http://www.aerotech-rocketry.com/) G54W-M reload,
20 [Polecat Aerospace](http://polecataerospace.com) 5.5 inch Goblin kit on one
21 of the relatively new [Aerotech](http://www.aerotech-rocketry.com/) I245G-M "Mojave Green" green-flame reloads. But by far the highlight of the day was
22 flying my [Giant Leap](http://giantleaprocketry.com) Vertical Assault on
23 a [Cesaroni](http://pro38.com/) J335 red-flame reload... with
24 serial number 1 of [TeleMetrum](http://altusmetrum.org/TeleMetrum) on
25 board collecting our first-ever flight data!
27 From the ground, it looked like a textbook perfect dual-deploy flight, with a
28 small drogue chute out at apogee around 4000 feet above ground, and the main
29 chute deploying at 700 feet above ground for a beautiful, soft landing only
30 a couple minutes walk from the launch rail.
32 The ejection events were controlled by a PerfectFlite
33 [MiniAlt/WD](http://68.178.208.82/cgi/PF_Store/perlshop.cgi?ACTION=enter&thispage=MAWD.html&ORDER_ID=!ORDERID!). The data recovered from it shows a big
34 negative spike in the altitude right at apogee, coincident with firing of the
35 apogee deployment charge. I have to assume this means the aft bulkhead on the
36 avionics bay in the reconstructed coupler section isn't sealing well, and some
37 pressure from the apogee deployment charge leaked in to the avionics bay
38 "fooling" the altimeter into thinking the altitude was lower for a sample or
39 two. Clearly, that needs to get fixed before that airframe flies again.
41 Further evidence that we had a mighty kick from the apogee ejection charge
42 was discovered when we went to clean the motor casing. The Cesaroni reloads
43 are packaged in a plastic liner tube that slides into the reusable aluminum
44 case. When we pulled the spent reload out of the case, it was significantly
45 shorter than when it was loaded, suggesting that the ejection charge forced
46 the forward closure on the reload backwards compressing the heat-softened
47 plastic. This could be evidence that the reconstructed coupler was slow to
48 separate from the booster airframe due to excessive friction?
50 The flight data recovered from the
51 [TeleMetrum](http://altusmetrum.org/TeleMetrum) board looks great until
52 apogee, when the data collection stopped. Since I flew firmware that was
53 compiled and flashed on the flight line from Keith's latest git commit as
54 of this morning, it's entirely possible that there was a software bug that
55 caused data collection to terminate at apogee. We'll investigate that. But
56 I personally think what actually happened is that we experienced a temporary
57 short in the power supply at the time the apogee ejection charge fired. On
58 extraction of the electronics sled from the avionics bay this evening, I
59 noticed that one of the mounting screws has gone missing. If it wasn't snug
60 enough, and vibrated loose during flight, it could have been torn loose at
61 the time of the ejection event and shorted something as it rattled around in
62 the avionics bay. The screw is now just missing, but may have fallen out
63 when we were extracting data on the flight line just after the flight without
64 being noticed at the time. So I'm not inclined to worry much about this, at
65 least until we can get some more flight data!
67 Keith post-processed the raw flight data and presented me with a
68 [plot](http://www.altusmetrum.org/TeleMetrum/flights/sn1-flight1.plot.ps)
69 showing two traces, acceleration and barometric altitude. The data from the
70 accelerometer closely matches the published data for the motor we flew, which
71 is a really cool result, and my 10-year-old son enjoyed figuring out why the
72 rocket showed negative acceleration after the motor burn out but was still
73 climbing. (See, there really is some science education hidden in the fun!)
75 All in all, we had a great time, and it's totally cool to have data from a
76 first flight of [TeleMetrum](http://altusmetrum.org/TeleMetrum)! Can't wait
projects / web / gag.com / blob