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Bill was on hand to help out, so we drove out to my launch site and set up the pad and controller. Electronics were on, igniter in place. All clear, 5,4,3,2,1 and ignition. The slightly larger propellant load (1.35 lb.) lit quickly and the rocket leapt off the launch rail. The rocket quickly coasted out of sight, both Bill and I gazed upward, trying to reacquire the rocket. Then pop! That was a good sign as we heard the apogee charge going off, but still no rocket. Several seconds after the pop I finally sighted the rocket coming in.
Here's a really enlarged image of the rocket coming in.
As you can perhaps see in the image, the drogue chute isn't fully opened up. Luckily, the drogue chute was large enough to destabilize the rocket to the point where it was coming in almost like a glider plane. See the angle the rocket is at? It came down at that angle pretty much the entire way. I was still hoping for main deployment, but it was not to be. There just wasn't enough drag to pull the main chute out of its deployment bag. The rocket landed just behind a small rise, so we set out to find the rocket and check for damage.
Here's the way the rocket was found.
As luck would have it, the soft, wet ground prevented any damage. The rocket was recovered with no apparent damage. My next question was, "How did the altimeter fair?". The cause of the collapsed drogue was quickly apparent. The piston had flown through the shroud lines, causing them to tangle. I've heard of nose cones going through shroud lines, but never had it happen to me. The PIRM2 had fired, and just a little more tug by the drogue and the main would have deployed. I turned off the electronics and we headed back to the van. Once everything was packed up, we headed home. I was anxious to see how the altimeter had held up during the hard landing.
Back home, I removed the altimeter module from the rocket. Everything looked OK. No loose wires, batteries or components. So I hooked up the serial cable from my PC to the altimeter and ran the data retrieval program. The data was fine, here's the results.
Ground Level: 3137 data values= 28.32" Hg= 0'
Maximum Altitude: 2831 data values= 87.351 kPa= 2,683'
Main Deploy: 3073 data values= 93.916 kPa= 597'
So the altimeter continues to work well, the reported altitude was within 90' of the software predicted altitude. Before this flight I had sanded and repainted the upper body tube. Suppose that slick new paint gave me the extra 90'? Could be, but I am running the software at a drag coefficient of .65, and that's a little high I'm sure.
I need to take a look at the drogue, and make sure I'm packing it properly. Had the drogue not tangled, I'm sure deployment would have been fine. I think I may need to lengthen the shock cord, that may have been the cause of the tangled drogue. I used more of the shock cord between the PIRM2 and the main anchor eye bolt to make sure the main chute would make it all the way out of the body tube. That shortened the rest of the recovery harness. The nose cone and piston may have snapped back into the parachute because there wasn't enough shock cord to decelerate the ejected nose cone and piston.