My Grandmother was named "Mary Roberts" and I always found that slightly amusing.
Mary helped me out one time... I had bought a "Maniac" to launch my Astrocam on top with a D motor, and of course on the first flight the rubber band shock cord popped, dropped it from altitude, and it core sampled... it had rained a few days before and the top layer of soil was damp and relatively soft, but the ground was much harder and drier underneath, which was a "perfect storm" for the core sampling rocket-- it hit the ground, penetrated about 2 inches, and then started to "accordion" the tube to dissipate the forward momentum. The tube accordion-folded for about half its length, when suddenly we heard a very loud POP! or "POW!"... When I got to the rocket, which I saw had impacted maybe 30-40 yards away and was visible the entire time, I found that the other half of the tube was completely blown out, nearly down to the fin can. Apparently, the tube penetrating the soil had very effectively "sealed off" when it core sampled-- in fact the front inch or two of the tube buried in the ground was practically unscathed. The tube had accordion-folded on impact above that point, from the ground up, which of course shortened the effective length of the tube and the air trapped within it was forced to compress. At some point, the compression of the air inside exceeded the tube's containment strength, and the tube had "blown out", opening up along one of the spiral seams and blowing outward to vent the trapped air inside the tube. I did manage to cut off the tube about 2 inches above the fin can where the seam separation stopped and the tube was undamaged... Added a stage coupler and made it into a booster for a regular Maniac.
Of course I was rather ticked at Estes and let them know about it. First flight and the rubber band snaps and demolishes the rocket! I got a new Maniac kit in the mail with a nice letter from Mary Roberts, which I really appreciated. Even got a pack of motors IIRC. I guess in retrospect, I should have been suspicious about the cord... I bought the rocket from a local electrical and crane shop that had a small storefront over in Wharton-- the owner was a model airplane and model rocket enthusiast and he kept some hobby stuff in the store front along with the chokers and cable ends and various and sundry electrical fittings of the usual business... even had a rotary display rack with rocket kits hanging on the pegs in the shops front window, which was facing west. I didn't think about it at the time, but the hang tag on the kit was sun bleached from being on the display rack in the window in the afternoon sun for who knows how long... I'd bet cash money, in hindsight, that the rubber cord got "sunburned" from too much UV streaming in from the afternoon sun and that fatally weakened it, causing it to snap. Oh well...
Never been much of a fan of the Estes rubber band shock cords anyway. From that time on, I've ALWAYS just tossed that rubber band crap into 'spare parts' bin and cut off what I needed from a good old roll of sewing elastic. MUCH sturdier and even if the rubber core fails, the webbing will prevent a separation, unless of course it's a catastrophically late high-speed ejection or something like that where NOTHING would hold up to the strain...
Later! OL J R
