Flight Log for 13 May 2000, Boeing Space Center, Kent, WA

High overcast, breezy -- 10-15 just before the launch, dropping to 5-7 during the launch, then starting to rise again toward the end.
Model Flt 
#
Recovery Type Motor Comments
Astron Cobra (repro)
1
12" plastic parasheet
3x Estes 1/2A6-2
This was my first flight of a Cobra since I built one in grade school in 1973.  This one went better -- that first Cobra only launched twice; the first time, only two motors lit and the rocket traveled downrange about 1/4 mile under power; the second time, one motor CATOed and the rocket was destroyed.  This Cobra, despite an early ejection by one of the 1/2A6-2 motors, lit all three motors and recovered successfully -- flight was spectcular, but short.
Astron Cobra (repro)
2
12" plastic parasheet
2x Estes A8-5, 1x Estes B4-6
This was an experiment: everything I knew said this ought to give a nominal boost and slightly prolonged burn due to the one higher impulse motor (but with identical initial thrust profile) -- but I'd never heard of anyone doing it.  Unfortunately, I didn't learn much on this flight; only the A8 motors ignited, and though the delay was longer than I'd have liked for the altitude, recovery deployment was above ground and the rocket was undamaged.  If at first you don't succeed...
Astron Cobra (repro)
3
12" plastic parasheet
2xEstes A8-5, 1x Estes B4-6
This time, after carefully scraping the propellant inside the nozzle of the B4-6, all three motors ignited, and the rocket boosted straight.  There was no discernible change of course at burnout of the A8 motors; the continued thrust of the B4 carried the rocket high and straight.  The shorter delay and shorter burn of the A8-5s meant they deployed the recovery system, again nominally, and the rocket was recovered a couple hundred feet away, still with no damage other than some blast scorching of the nylon cap nut that served to retain the motors.
BBBertha!
1
12" plastic parasheet
Estes B6-4
This is the newest 24 mm Big Bertha clone in my fleet -- this one is a repro, built from scratch and JimZ plans rather than from a kit, but structurally and aerodynamically identical to a kit Bertha.  On this one, I experimented with a vinyl decal custom cut at a local shop; for just under $8, I got a graphic good enough to go on a car or a professional's shingle.  With an adapter to take the 18 mm motor, boost, coast, and deployment were nominal -- and not one speck of wadding was used; this rocket flies without it due to incorporation of a recovery compartment as put forth in Tim van Milligan's Model Rocket Design and Construction.
BBBertha!
2
12" plastic parasheet
Quest C6-5
This flight showed some waggling in the tail -- I don't know yet what's causing that; it might be nozzle irregularities in the Quest motors, though there's nothing visible when I look at unfired or expended motors.  In any case, other than the waggle, the flight was normal in every respect.  I noted on this and the previous flights that the ejection is nearly silent; I can only speculate that this is because the large dead space within the airframe, behind the narrow annular exhaust around the recovery compartment, acts like a muffler to absorb the pressure wave from the ejection.  In any case, every launch so far has been like this, ejection very quiet compare to other similarly sized models (like the Cobra).
BBBertha!
3
12" plastic parasheet
Estes D12-5
With this flight, I started to really miss the D12-7 I can't get any more.  The Bertha is still rising pretty rapidly at ejection with this motor, where the -7 version had it just laid nicely over on deployment -- that means I'm ejecting at over 30 mph when I could be ejecting at near dead stop, if only Estes hadn't decided the D12-7 wasn't profitable.  I might have to start flying this model on the D15-7 Aerotech reloads instead, or CHAD stage it C6-0/C6-7.
BBBertha!
4
12" plastic parasheet
Quest C6-5
Again, the tail waggling -- but everything else was nominal, and BBBertha! settled into the kind of ho-hum perfect flights one expects from a Big Bertha.
BBBertha!
5
12" plastic parasheet
Estes B6-4
Last flight of the day -- the recovery compartment really saves prep time, since I can repack the parachute while walking back from recovering, and simply change motors (takes a couple minutes, including seating the igniter) and I'm ready to fly again.  In any case, eight flights on two new models, thirteen motors, on a day that started out with me flying a kite instead of rockets -- definitely worth the trip.


Back to 8 April 2000


Forward to 4 June 2000


Back to Launch Logs page.


Back to my Home page.