Tuesday, November 9, 2010

Plaster Blaster 2010: A new personal record of 21,915'!!

This last weekend's Plaster Blaster 9 launch featured amazing weather, many cool projects, more spectators than I've ever seen at Plaster City, and my parents even drove out from AZ to visit. Nice!
As always I'd planned more flights than I'm capable of completing on this three-day weekend. At a minimum I had hoped to fly Der Red Mix II (K635 Red Thunder, air-starting 2 x I345 White Thunder), my Nike Smoke on a pink M1675, and Em-Sem-Fity with a CTI M795 in a drag race with Frank Hermes and Art and Tom Just from AZ. Jack didn't have the K635 in stock and I was too tired to prep the Nike Smoke on Sunday so the only flight I completed was for the drag race.
I started prepping the segmented M795 moonburner from CTI late on Friday night so it could cure for Saturday morning. Despite arising early on Saturday I was still tardy for our agreed flight time of 10AM. Art and Tom had their M650 rocket sitting on the pad for awhile then Frank headed out about 10:15AM. I was finally done prepping by about 10:30AM but, when I headed out there, Frank had just dropped a rail guide. He was confident that he could quickly a) swap boosters and b) increase the black powder load in his CD3 system. I set up Em-Sem-Fity on the pad, armed the electronics, and loaded the igniter. Astonishingly Frank was done with everything in about 15 minutes!! We were a bit concerned about the thin, uniform cloud veil right above us but we agreed everything should be fine. Upon ignition Frank's rocket leapt off the pad at astonishing speed and smoked both Art/Tom and I thus winning the first-to-1000' portion of the informal contest (Thanks to mom for shooting this sequence :)
Then our two remaining rockets lifted off almost simultaneously:
KO captured this video of the liftoff with her Flip MinoHD video camera (watch full-screen in HD on YouTube for best effect):
Upon liftoff my rocket appeared to be a bit overstable and coned some on initial boost. This is strange because this motor weighs almost the same as last year's M750 and that lifted off straight without even a wobble so I'm confoosed. The flight path was several degrees toward the southeast, it punched through the cloud layer, and I heard it burn for another 6-7 seconds!! Unfortunately Art/Tom's rocket failed under boost and they're not yet sure what happened. Those dudes are super nice and they say they'll come back next year with a 20k attempt.
So I have my CSI radio beacon installed and I get a nice clean signal boost when the thing blows out of the carbon fiber tubing. Having heard that I told our RSO, Ken Sparks, that I had attained apogee safely and started following the signal with my Yagi antenna. I walked for several minutes with a nice clean heading NE toward the prison then... nothing. Static. Normally static means you've crashed the transmitter but, in this case, I knew it had been falling for about the expected amount of time under streamer/'chute. Undaunted I continued to pursue that last line toward the NE. During this long walk I thought I heard a periodic blip in the static and redirected to see if its strength increased. After about an hour of meandering I decided that I had to scale the highest 'local' feature and walked up to the abandoned quarry to the east. I removed my sandals and climbed the loose gravel to the top of the 40' mound, turned on my receiver and... I had my signal back!! It was pointing me north right toward where it had earlier so I should have simply stuck to that line. As I continued walking the signal would strengthen and fade as a function of elevation. Keep in mind this was on 'long range' so this thing still had to be far away or in a really deep ravine. At one point I feared that it had landed on prison grounds or in one of trees hiding the prison from view. Finally I found the thing laying on the ground about 0.2 miles north of the prison:

I used Google Earth to map the landing destination. The red straight line is roughly 3.2 miles as the crow flies and the yellow, meandering path is my best guess on my walk of ~4.9 miles:
I was in almost constant phone contact with Frank who had just recovered his 22,176' flight 6.8 miles north of the launch site. He was kind enough to trek out to pick me up. I didn't notice my exhaustion until after I'd found Em-Sem-Fity but I was pooped. Frank took this photo as I approached:

I downloaded the altimeter data and here's the ARTS2 summary and graph with a barometric peak of 22,080':
And the Raven summary and graph showing 21,749' for an average of 21,915':
I also plugged the flight info into the ARTS2 software and here's the motor analysis:
Now allow me to be very clear: I am not taking anything away from Frank's second victory on peak altitude here!! However, none of those motor attributes match those on the ThrustCurve site. Who knows how accurate this analysis is but, again, I'm left wondering if reload aging impacted performance. One of these days I'll need to buy a pristine motor and eliminate this aging variable for my peace of mind.
This was a great launch and I'm grateful to all the club volunteers who made it happen! The spectators, including my folks, were really stoked so I consider Plaster Blaster 2010 to be a great success. I posted the rest of my pictures here if you're interested. Thanks for reading this saga and cheers to a great PB 2k11!

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