Flight Log for 6 August 2000, Monroe, WA

Overcast 1000' AGL, wind 0-3 variable, changing to partly cloudy and 2-5 W after noon.
Model Flt 
#
Recovery Type Motor Comments
BBBertha!
14
12" plastic parasheet w/ central spill
Aerotech RMS 24/40 D15-7T
The launch was held until noon due to the overcast -- with our waiver specifying 1000' separation below any overcast, we were grounded for any models that need a waiver, and even the "Model Rockets" that could be flown without the waiver had to keep at least 500' below the clouds -- rather than have RSOs and pad managers have to turn away rockets that might go too high, the decision was made to hold until the clouds burned off, which was about noon.

This was the first time I've flown my 24/40 case in an Estes class rocket -- I've avoided doing so in the past because, in most cases, the motors available are too powerful for field and weather conditions in light rockets; I don't want to repeat the experience of losing my 18/20 case on its first flight back in 1996.  This time, however, I was using reloads to duplicate a motor that Estes has discontinued, the D12-7.  The concept worked very well indeed; ignition was immediate on the Copperhead that came with the reload kit; the rocket boosted straight and roll-free as always, and ejection was just after apogee, as desired.  I'll have to fly the combination again, especially since the Aerotech D is cheaper than a Estes D12 in any case.  Might even have to dry the D9 reloads, if I can verify that they're certified.

BBBertha!
15
12" plastic parasheet w/ central spill
Aerotech RMS 24/40 E18-10
The weather conditions were excellent, and the grass on the field wasn't too tall; I decided it was time to try an E motor in the BBBertha! and proceeded to buy a pack of E18-10 motors.  I loaded up the reload, and again ignition was immediate on a Copperhead.  I'd have expected this to be the right delay -- three seconds longer than what's right on a D, with twice the impulse and slightly higher thrust.  I'm sure I didn't get a bonus delay; I counted it out, and the rocket did go high enough to be hard to track.  None the less, it was well past apogee and descending when it deployed.  The result was an opened snap swivel, losing me the parachute, and a zipper about an inch long.  Then something happened that only a Bertha could manage; after tumbling down well over a thousand feet, despite the weight of the reload casing in the mount and the nose cone dragging at the end of the shock cord, the rocket stabilized into a vertical plunge descent and took a perfect core sample a couple inches deep.

There was grass in the recovery compartment, and honest to goodness dirt in the mouth of the tube -- but amazingly, the tube didn't crumple at all; the only additional damage from the unconventional landing attitude was a chip out of one fin from the impact of the nose cone, and the motor mount tearing loose inside the airframe.  The rear centering ring failed, not the airframe tube, so I'll easily be able to remount the original mount with a new rear ring (and a reminder to glue the front ring, too, this time); the zipper won't be hard to fix, though the recovery compartment will complicate repairs somewhat, since I can't just cut the tube and couple on a new section unless I do it behind the compartment, which will involve destroying the $8 decal.

Still, BBBertha' will fly again.

After this flight, it was time for my shift at LCO, and I took on a second shift while still at the table; then it was time to break down the range and go home; the delay waiting for the clouds to break had cost two hours in the morning, leaving only four hours of good flying time (some of which was spent talking instead of prepping and flying, of course).



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