BT-70 classics

Jul 16, 2003 24 Replies

Dave, The simple way is to use a sawed-off, spent 18mm case as the adapter. The T motors will usually friction fit fine, sometimes a wrap or two of tape is needed.

The big problem you'll have right now is not blowing it up. The current

1/2A motors have pretty hot ejection charges. I haven't witnessed it with any full-A T-motors, so those may be OK. And I doubt you really want to fly it on composite 18mm short motors :)

Doug

Well, here's one I did.

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It uses the stock BMS cone. It crashed on its inaugural flight at NARAM last summer. The upper stage E9 didn't light. At this size, it's a little slow off the rod. This is when I wished Estes had a large core D motor (~D40) to really kick it off the rod.

I've also thought about integrating some

13mm MMTs into another booster for getting it up more quickly.

I suppose an E30 to an airstarted E9 shoulda/coulda been a consideration.

The nosecone was smashed, but I rebuilt it. The booster suffered a pretty good ding (unrelated to the crash) and has been repaired.

I was able to salvage everything from the upper stage except the tube. The rings and MMT assembly were re-used in the repaired rocket along with the fins. I just need to add some paint and it will be good as new.

Doug

Close. In addition to smaller ID, the LOC's OD is also larger. BT-70 2.175" 2.217" LOC BT-2.14 2.14" 2.26"

Bob, for HPR I agree. I hate seeing folks 'glassing stuff when there's already a suitable tube available. LOC's 2.56" tube is a perfect example. With its

0.035" wall, it's perfect for use in place of 'glassed BT-80. I much prefer to spend a few bucks and save a couple hours.

As for the LOC 2.14" tube, I'm torn. With its 0.060" wall it's really a motor tube. It's fine for that, and for HPR airframe, but it's really heavy for lesser applications - ie, mid-power.

That said, there isn't anything (that I'm aware of) in between BT-70 and BT-2.14, so the user would have to glass his own BT-70 I suppose.

Doug

I already posted to this thread USR tube is 2.17 x 2.25 and the data from tests is at

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I heard that a certain teammate of mine bought a set of BMS parts to clone this classic last NARAM...

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

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