Flight Log - 2001-08-04 - Ocotillo Club Launch

Woke up at 5:00 a.m. so that I could be at the launch site early. The sun rose as I made my way over the Tecate Divide and down into the badlands. By the time I got there (about 7:00 a.m.), it was already starting to warm up. During the day, the temperatures exceeded 110' with moderate winds. It was nice enough for a while in the morning, but it got really hot by noon. I was processing water about as fast I could drink it. The heat made the walks to get the rockets difficult. I can see how someone could perish in a few hours out here. At 1:00 p.m., I decided it wasn't worth the effort anymore and cut out. The drive was hot and hard as well, with winds and "no air conditioning for the next twenty miles". Still, I was on the range for a good 5 hours, and got four flights in. Some better than others :-|

Flight #1 - GPARS #3 (I211-M)
GPARS third flight.
actual: 2360 ft
predicted: 1958 ft.

One of my goals for today was to try to get GPARS flying right, so for the first flight of the day I chose to send her up on an I211M. The boost was nice and straight with the rocket climbing nearly out of sight. It opened up and separated correctly, but the parafoil parachute did not open all the way. It remained folded as the electronics module made it's way to the ground. The parafoil came down a little quicker than the booster, but there was no damage to the innards. Obviously, I never had R/C control of the chute.

The booster landed about 1/2 mile away, the parafoil a little less. Even at 8:00 a.m. it was pretty hot. I started thinking about a shortened day.

Flight #2 - DoubleTrouble #3 (J90-L shaved)
Double Trouble's third flight.
actual: 2762 ft
predicted: 2578 ft

Click here or on the photos below to see a 3M mpg movie of this flight.

For the second flight of the day, I went with DoubleTrouble on a J90 again (thanks to John for loaning/giving me the motor insulator tube ... it's a little worse for wear and tear, but I still have it if you want it back). My theory was that I could leave the delay longer and force the electronic deployment to work. So I thought I cut the delay down by less than an 1/8" (less than 4 seconds), which, according to sims, would still allow for 3 seconds of freefall after apogee, which should have been enough to let the altimeter kick in.

As noted on the film, the motor deployed early, I'd say only 6 or so seconds after it stopped burning. hmmm... I wonder if it was really a J90 medium? Don't think so! Even though it wasnt pretty, there was no apparent damage to the rocket. The mains deployed on cue. After the mains deployed, the drogue chute got wrapped up in itself, the nomex heatshields, and the electronics module. Seems like the drougue should fire out the top. Hmmm ... but then I couldnt use motor backup (cuz the mains go off based on altitude, much later, and not based on time). Oh well, I'll have to try again later ..

Flight #3 - SkyDream #9 (K185-L shaved)
SkyDream's last flight.

Click here or on the photos below to see a 2.8M mpg movie (with analysis) of this flight.

O.K. So now it's hot out here. I had wanted to fly SkyDream on a K185 again so I could get some good footage. John had a K185 so I bought it and built it. I'm pretty sure I messed up, and I know how. When I was finished building the motor, I realized (as I had on a flight at LDRS) that I had used the wrong aft closure (one of mine has holes drilled in it for motor retention, and the other doesnt), so I hastily cleaned the aft closure from DT's J90 and replaced the closure on the K185 after I had built it. The first photo below shows SkyDream under boost.

Either my motor assembly was wrong, or as Andy suggested, about 1 out of 3 K185's has blow by problems, but I had my first motor failure (ever) on this flight. About 3 seconds into the long-burn 7.5 second boost, the motor blew by the fore closure causing separation under boost. Way under boost. In the second picture below (and on the movie) you can clearly see the nose cone and parachute for a split second.

I gained a new respect for these motors on this flight. As you can see on the film, the rocket barely changes motion, corkscrewing slightly when the separation occurred. The top body tube came off and rapidly pulled out the parachute. A few milliseconds later the parachute opened, and really started putting stress on the shock cord. I'm not exactly sure of the order of operations, but, the booster continued accelerating upwards almost unimpeded as it snapped the 1" nylon strap that brings the shock cord out of the booster (probably severly zippering the booster in the process), broke and bent open a 160lb test quicklink that connected the shock cord to the top half of the rocket, and ripped every 1/8" nylon shroud line on the parachute, all like they were'nt even there, in the blink of an eye.

I accidentally turned the camera off when it was under boost and went wrong. Searching the skies, I finally heard, and then saw the booster came in ballistic about 1/4 mile behind the flight line. I was surprised how clearly I could hear the hiss as it came screaming in at, what I'd have to estimate was upwards of, or maybe even over 500 mph. It hit the ground and bounced, sort of. When I got to it, it was still on fire from the blow by ... it must have been like a blowtorch, coming down that fast on fire, cuz it melted the aluminum anti-zipper strap, and all that was left of the booster is what's shown in the picture above, a little wad of burning stainless steel mesh from the motor baffle, and a scorched mark on the ground. There were only minute (smaller than 1/4") pieces of the rest of the booster around the crash site.

When I got back to the flight line, someone had recovered the top of the rocket and the chute (thanks!). The nosecone free fell to the ground, and the parachute must have landed some distance away. The altimeter had broken free of it's mounting but appeared to still be working on a quick test. The oddest thing about this flight was that, later, while retrieving the Arreaux after the final flight of the day, I found SkyDream's shock cord out in the middle of the desert. It was only after I found it, lying by itself, that I was finally able to piece together what had happened to SkyDream. The shock cord was still attached to a little piece of the nylon strap on one end, and had a wide open quicklink on the other end. Wow. It's weird how it would have enough force to separate both sides. The failures must have been nearly simultaneous.

Flight #4 - Arreaux #24 (G80-10)
Arreaux Rocket-Cam Dual Launch

Click here or on the photos below to see a 4.9M mpg movie taken from the rocket during this flight.

I'd had high hopes about getting a bunch of flights in today but was starting to feel tired by about noon. One of the things I was hoping to do today was a dual launch, filming one of my other rockets from the Arreaux during flight. Also I had rigged a new apogee triggering mechanism and parachute harness on the Arreaux and glassed the body tube, and so wanted to see how they would all work. However, I really didn't want to clean a motor and prep one of my other rockets at that point. So I suggested to one of the club members who was loading his rocket up at the same time that we attempt a dual launch. Below on the left is the Arreaux taking off, on the right is the other rocket a little later.

I was filmed it from the ground as well, though it's not really worth seeing, as Andy volunteered to press the buttons. I had guessed we needed about 7 seconds from when the Arreaux took off to when we pressed the second button, allowing 2 seconds for the second rocket to start.

For better or worse, the second rocket took off about 2 seconds after the Arreaux. It didn't really matter that much because the apogee trigger went off at lift off, and instead of a hi-res movie from apogee I got a low res movie of most of the flight. However, the new parachute rigging seems to have worked. By attaching a kevlar thread from the nosecone back to the shock cord, I had rigged it so the camera would point down while under chute. As you can see from the above picture (or from the film, by clicking on the above links), the camera is clearly pointing down while under chute, revealing the roads leading into the area and the flight line, much improved from previous Arreaux-Cam movies.

Summary:

Well, today was a hot one. I'm not really that dissapointed about SkyDream cuz we build em to fly em, and if you fly em, they're gonna crash! I would have liked to test GPARS more, but it got too hot and there were other rockets, experiments, and things to do today. Thanks to the club and folks that were there to help and share.

See ya next month!

- Pat