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Possible Cobra B6-6 motor problems...
#1
I got about four 3-packs of B6-6 motors from either the 1990s or 2000s...they had dust on the packages. The local Hobby Shop sold them and 15 other packs of various bubble pack motor packages for $50 total when they got out of the business. I jumped at the deal. I cracked open the first pack last month and suffered a melt down with this as the upper stage of a two-stage B6-0 pairing. Since the second stage burned, I'm now thinking perhaps the upper B6-6 have "gone bad" somehow. How likely is it that these "Cobra" B6-6 might be "bad" and what can i do about it?   To my knowledge, these and all t he motors I bought, had been kept in a temperature controlled showroom hobby shop for years and years.  Other than dust and perhaps some sun fading on the package, there's no obvious signs of damage.

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#2
that upper stage b6-6 didnt light, but have you tried it alone, without trying to stage?
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#3
Kirk, as long as there was no physical trauma (generally you can see small cracks in the nozzles or dislocations of the end caps in those with ejection charges) and no temperature cycling between hot/cold etc the motors should be fine.
I launched some BP engines from Estes last year that I had hanging on my basement wall from the 1970's and they worked just fine! They were sealed in packages which were covered with dust.
That being said if you are contemplating using them in a model that has some special significance you might want to not do that, just to be on the safe side, since you really don't know how those were stored/handled by the hobby shop...
Greg Young - L3
TRA 00234
NAR 42065
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#4
(05-08-2016, 09:56 AM)tomsteve Wrote: that upper stage b6-6 didnt light, but have you tried it alone, without trying to stage?

No, it didn't appear to NOT light, but perhaps went all at once.   The burn was destroying the bottom of the second stage launch tube, though the fins were "fine", the tube was half gone.
That makes me think the second stage didn't separate, and or, part of the second stage slipped down the shaft of the two-staged motors.  But I don't know.
The whole thing (motors) ejected and felt to the ground on their own.... striking an Elmer who wasn't watching.

(Does that qualify him for a "SpaceLab Award"?)
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#5
How did you interconnect the two stages / in what rocket?

I've heard of a lot of accidental subs of masking vs. cellotape, which can cause them to stick-n-burn.
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#6
(05-12-2016, 12:48 PM)dhbarr Wrote: How did you interconnect the two stages / in what rocket?

I've heard of a lot of accidental subs of masking vs. cellotape, which can cause them to stick-n-burn.

Agreed. That's the question at hand. Masking tape, electrical tape, anything that won't melt instantly is no good for staging BP. The other possibility is that the stage itself couldn't separate. Was it too tight?
John S.
NAR #96911
TRA #15253
MDRA
Level 1, 2014-Mar-15 -- Aerotech Sumo, H133BS
Level 2, 2014-Jun-21 -- Giant Leap Vertical Assault, J240RL
Level 3, 2016-03-12 -- MAC Performance Radial Flyer, M1101WH, 13,028 feet
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#7
The two were staged by a wrap of "magic mending tape" just once around. However, both motors had at least one and a half wraps of masking tape holding them into each top and second stage to be snug. Even at that, both motors ejected and dropped as a unit, striking a fellow rocketeer who wasn't paying attention. (Didn't hurt, just startled him.)
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#8
You should only use cellophane tape when taping motors together for staging purposes.  Other adhesive types of tape are a bit too strong for that purpose.  You may need to search a little to find some cellophane tape, though.
Michael Toelle

NAR 31692 L1
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