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Vanel
08-04-2005, 10:38 AM
Anyone know of a vendor selling BT-30s? I have checked places like Totally Tubular, but didn't see any tubes matching the specs (ID and OD).

stefanj
08-04-2005, 11:07 AM
Totally Tubular does sell a T-30, but it may not be on the "current" catalog page.

Semroc sells some similar toobs.

In neither case are these parallel wound toobs.

Vanel
08-04-2005, 12:08 PM
Stefanj,

According to Ninfinger's BT listing, the BT 30 has an ID of 0.725" and an OD of 0.765"; I checked Semroc's site and couldn't find anything closer than the ST-7, which is BT-20 equivalent. Totally Tubular lists a T-20+, which has an ID of 0.744" and an OD of 0.770", which is close (the tube slips over a BT-20). However, their T-30 is listed as having an ID of 0.656" and an OD of 0.700", which is smaller than a BT-20 :confused:

Is this a typo?

BMS makes nose cones for the BT-30, so the tubes should exist somewhere.

stefanj
08-04-2005, 02:23 PM
Write to Totally Tubular and ask. I bought BT-30 sized tubes from them several times.

I suspect the listing for the T-30, as shown on their catalog page, is inaccurate. The ones I bought from them worked perfectly with the BMS BT-30 sized cones.

Doug Sams
08-04-2005, 02:45 PM
(Totally Tubular's) T-30 is listed as having an ID of 0.656" and an OD of 0.700", which is smaller than a BT-20 :confused: Is this a typo?Yes, it's a typo. He inadvertently entered the T-.700” dimensions for the T-30 dimensions. I've used TT's T-30, and it works great. And after you fill the spiral and paint it, nobody can tell it's not convolute wound without looking inside the tube. Furthermore, no one has dissed my Scout and Sprite clones for not using authentic parallel wound tube :)

Also, Sigma Rockets (formerly known as the Advanced Rocketry Group) has T-30, too:
http://www.sigmarockets.com/arg_tubes.htm

BMS makes nose cones for the BT-30, so the tubes should exist somewhere.Now don't go using logic. We'll all get screwed up then :)

Seriously, what does Semroc use in their Sky Hook clones? Wasn't that originally BT-30? I haven't looked to see for sure, and quite frankly, it doesn't matter to me. I've never thought the Sky Hook or Mark needed the heavier tube since they weren't tumble recovery anyway. I have a Semroc Sky Hook stashed at the house for my daughter's college tuition :) I'll have to check the tube tonight.

Doug

Vanel
08-04-2005, 09:14 PM
Thanks guys - I'll email Totally Tubular.

The OD on the Semroc Sky Hook is 0.759" - This is the same as their ST-7 (BT-20) tube.

SEL
08-05-2005, 12:28 AM
Now don't go using logic. We'll all get screwed up then :)

Seriously, what does Semroc use in their Sky Hook clones? Wasn't that originally BT-30? I haven't looked to see for sure, and quite frankly, it doesn't matter to me. I've never thought the Sky Hook or Mark needed the heavier tube since they weren't tumble recovery anyway. I have a Semroc Sky Hook stashed at the house for my daughter's college tuition :) I'll have to check the tube tonight.

Doug

Semroc uses their ST-7 tube.

Sean