12-10-2007, 08:04 AM
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Ye Olde Rocket Shoppe
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Join Date: Jun 2004
Location: Milwaukee, WI
Posts: 6,485
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Quote:
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Originally Posted by Mark II
No, when I mentioned the part about them only having a spiral-wound version, I was referring to Semroc's BT-30.
I started ordering from Estes in 1967, but I don't recall ever seeing the engine mailing tubes (aka BT-40) during that time. My orders used to come in a long box - almost exactly like my orders from Semroc do!  - and the engines would come lined up end to end and rolled up in some newspaper, and then packaged in their own little parcel post box, as I recall.
I'm not 100% sure about this, though; it was a long time ago, I only had about 3 or 4 orders with them altogether (didn't have much money then) before taking a 30+ year hiatus from the hobby, and nothing that I had from that era has survived (my folks threw away all of my rocket stuff - including live engines!  - when I went off to college). 
Mark K. |
Mark,
The engine mailing tubes and the BT-40 were two different animals. The BT-40 was from what I recall leftover stock from MMI. I have some scratch-built rockets here that I bought off of eBay six or seven years ago that have BT-40 tubes and those old, rubber nose cones. This tube had an inside diameter of .765". They had a balsa cone, a plastic skyrocket cone (fit over the outside of the tube) and two rubber cones available for this tube. The BT-40 size derived from the skyrocket size tube if I'm not mistaken.
The engine mailing tubes were much larger in diameter and much thicker-walled. Estes only offered one cone for the engine mailing tubes. That was the BNC-MTD. This tube had an inside diameter of .937". |