Flight Log for 1 July 2001, Monroe, WA

Broken clouds in the morning, burning off to scattered clouds by midday.  Wind variable and light.
Model Flt 
#
Recovery Type Motor Comments
Viper X
3
18" nylon parasheet
2x Estes E9-4, 2x Estes D12-7
With five of the sample E9-4 motors our Section had received last month still available, I checked with other Section members -- and not surprisingly, there was a demand for some of the motors, but I was able to use two in this cluster along with a pair of D12.  I had intended to use D12-5, but found I was out of that delay; so chose motors with longer delays to let the E9 control ejection.  With no thrust blocks in the motor mounts, prep was identical -- ensure the piston is sliding freely and parachute isn't tangled in shock cord, wrap 1/4" masking tape thrust rings on all motors, install them in the tubes, insert igniters and plugs, put on the washer and nut that retain the motors, then pull the tapes from the igniter leads and twist them into a diamond pattern for use with the clip whip I made up last month.

With that done, I got the RSO check required for the (barely) G total impulse (about 88 Ns), requested a rail for pad assignment, and loaded up.  Ignition was prompt with four good flames, and the rocket boosted significantly higher than it had with four D12-3 installed -- in fact, the four second delay in the E9 turned out a little short, but with my zipperless piston, there was no damage and recovery was nominal.  I do note that descent is a little rapid; that's probably because the modifications to my Viper X to allow modular motor mounts and the zipperless piston have added nearly a pound to the weight compared to a stock Viper 4.  Still, good ignition, good deployment, and good landing with a short walk add up to a good flight.

Thug
18
24" nylon parasheet
North Coast F62-4
With the F62 long out of production and due to lose certification in the next year or two, I decided to burn one of the two remaining in my 29 mm motor bag.  Since I only have the short delays left, that decided me to fly the Thug, which hasn't been in the air since last September.  I verified the recovery system, added some dog barf (this rocket normally doesn't eject the barf; instead it function as a sort of labyrinthine baffle), and prepped up.  I'll really miss these motors; the included Laser Fire igniters are hot and easy to fire, the nozzle cap is the finest innovation in motor accessories since motor clips, and the burn is smooth and strong.  This one was no exception, with a straight boost and perfect apogee deployment; due to a small amount of arcing that this rocket has displayed ever since I reattached two fins following the canopy incident at NSL '98, it was over the flight line at deployment, and dropped under parachute directly into the spectator area, about twenty feet from where I was standing -- with lots of warning, no one was surprised or caught underneath.  In other words, just about as good as a flight can get with a model this size.
Spike (2)
31
18" nylon parasheet
Aerotech F50-6FWL
Checking my 29 mm motor bag had brought to light a F50FWL that's been in there for some time -- probably a couple years.  The Laser Fire igniter the vendor had supplied to replace the Copperhead had long since lost its pyrogen, so I used one of the large batch of Copperheads I got for about a penny each when Rocket Vision was liquidating.  After pulling off the hair fine copper shavings on the edge, and trimming the nozzle cap to allow secure retention of the Copperhead without sharp bends, I installed the igniter and loaded the rocket onto the rod.  Ignition included a  single sharp chuff, probably because the igniter slipped a tiny bit under the weight of the clips and leads, but then the rocket leaped off the pad for a nominal flight.  Recovery wasn't as close as the Thug, but was still almost among the other group of HPR capable pads -- about 100 feet from the launch point.
Viper X
4
18" nylon parasheet
4x Estes D12-3
With an hour to go before my LCO stint, I decided to prep up my Viper X again.  With no more E9s I backed down to the three second delay again.  Once again, all four motors ignited, but instead of coasting out the three seconds and ejecting near apogee, one of the motors ejected within a second or so of burnout, while the rocket was still rising at about 40 mph.  The zipperless piston, however, did its job, allowing the parachute (mounted directly to the piston) to turn around and decelerate the model with no signs of stress to the airframe or piston, and no chance for the rocket to fly through the recovery rigging.  The rocket did crack a pair of adjacent fin fillets, apparently on landing; that's no big deal, since the fillets, made of Elmer's Finishing Wood Filler, are strictly cosmetic in any case, and a little thin CA will make them stronger than before.

IMO, the zipperless piston system works well enough it should be considered for any large model or HPR rocket.  I hope to be able to post a page and/or send an article to Sport Rocketry soon with construction and design details.



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