Mach 1, BT-60 Black Hole EXT

3.5 gram charges are you sure you need that much? 1.5 should be plenty for sure no more than 2. Can't be more than 12" of booster tube to pressurize even less in the main tube section.

crossfire said:

3.5 gram charges are you sure you need that much? 1.5 should be plenty for sure no more than 2. Can't be more than 12" of booster tube to pressurize even less in the main tube section.

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Lol. I said just kidding in the post. It will be .8g.

Funny that was a good one. Sometimes at a launch a ejection will fire and it sounds like a shoot gun going off.

So I cut another ounce off this thing. I was using an eyebolt in the forward closure. But it was huge and heavy. So I took a carriage bolt and ground the head down until I had a nice Square block to drill into. Drilled a hole and angled the edge. Then took it to the sander and wire wheel to clean up any rough spots.



The new attachment weighs 8 grams. And I plan on using a heavier 1/4" kevlar to get me out of the body tube. It will handle the ejection charge and abrasion better than the 500 lb that will continue the recovery harness.



It will work in my Aerotech closure and the CTI motor adaptor plug.

Cool.

Andrew_ASC said:

Cool.

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So have heard a few people say that their club does not allow friction fit. Because it does not meet the requirements of positive retention. But then I also heard that that friction fit is allowed there if your recovery harness is attached to your motor case. Because even if you blow the motor case out the back it will still stay attached via the recovery harness.

Glad you called it - I was reading it and almost spat my coffee across the breakfast table when I read 3.57g...

swatkat said:

Streamer on top, chute 1/2 way down. Here's the sled... came in at 23g!View attachment 360705

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Where'd ya get the sled?!?

I need one.

Normzilla said:

Where'd ya get the sled?!?

I need one.

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printed by Aaron

I 3D printed it... IM me and I can make you one for cheap.

oops, wrong thread

I hate to ask dumb questions, but seem to specialize in them. In post #25 of this thread, you've sanded the BT until the crosshatched pattern appears. It's such a smooth, even sanding! Do you do this with a mandrel rotating the BT, or by hand with patience and skill?

I just used 400 Grit with a piece of soft foam and did it by hand.

After 4 months of rained out high power launches in Northern California.... We finally got a beautiful weekend and launched both days.

Today the BT-60 Black Hole went up on an I59wn. Had a great liftoff with fly away rail guides. Seemed to have a little wobble in the flight, possibly right as the cored grain finished burning and went to just the end burning.

Lost sight of it after the 8 second burn and it coasted for another 14 seconds. The Eggfinder mini never lost contact. And it landed 400' away from the pad.

Waiting on the pad


Good ignition


Fly away rail guides coming off


Gentle grass landing

Screen shot of quantum. I will hook the Raven3 up to the computer tonight.

I polished this up during the six-month fire danger season. I took the micro mesh kit to it up to 6000 Grit. The main parachute and Chute release were moved to the forward payload. The GPS remained in the nose sled. Hoping that the forward weight would help with stability a might have caused a little wiggle on the last flight.

I loaded up another I 59 and took it to TCC October Skies last weekend. I entered it in the 2-mile Target competition and did very well. I was extremely happy and surprised to see how much more performance I gained by a polished finish. And this launch happened with 10 to 15 mile an hour winds.



There was less then a 0.5% difference between the two altimeter reading.

Sweet flight! This should be a record.