12 fins and 3" of two stage good-ness

[Yoehahn]

Any chance you could post more detail on your inter-stage coupler? It looks far different from anything I have seen.

Also, How'd the motor retention work out for the sustainer? I assume good? I've always wanted to try using this method.

Sure thing. Anything in particular? I can do a full on build thread too, not much was salvageable from it..

And the retention worked Great! except the interstage coupler ripped out one piece of the threaded rod. It takes a lot more time than an aeropack, but it is MUCH more secure. I use a wide nut, then a lock washer and then a smaller nut on top. Ill get some close-ups.

 

[awseiger]

Sure thing. Anything in particular? I can do a full on build thread too, not much was salvageable from it..

And the retention worked Great! except the interstage coupler ripped out one piece of the threaded rod. It takes a lot more time than an aeropack, but it is MUCH more secure. I use a wide nut, then a lock washer and then a smaller nut on top. Ill get some close-ups.

Sorry to hear about the loss, it was a slick looking bird :-(

I'm mostly interested in how you kept the two rockets together without a coupler between them. Unless I'm not seeing something, It looks like your interstage coupler consists of rods sticking out of the booster and tubes along the sustainer?

And good to hear about the retention. Seems alot cheaper than an aeropack, especially for the bigger diameter motors.

EDIT: Derrrrppppppp Darkstars are 54mm motor mounts in a 3-inch body. It's early here in Budapest.... I'd still like to see the detail though, if you don't mind.

 

[Yoehahn]

Sorry to hear about the loss, it was a slick looking bird :-(

I'm mostly interested in how you kept the two rockets together without a coupler between them. Unless I'm not seeing something, It looks like your interstage coupler consists of rods sticking out of the booster and tubes along the sustainer?

And good to hear about the retention. It's a good way to get around using the Minimum-diameter retainers.

Nope, I had a coupler that went up about 3" Into the sustainer body tube. Im not cool enough to be that different and Dont worry about the bird, She will be flying On May 18-19th. at least once. Also, an Aeropack does in fact fit in the 3" coupler tube, I just figured this would work just as well since I don't use the motors ejection charge. And I didnt have enough time to order an aeropack.... but thats a different story.

 

[Yoehahn]

The AT 38/720 case and adaptor

 

[Yoehahn]

More videos! Enjoy

The Success:
[video=youtube;yLLWmdyfk-U]https://www.youtube.com/watch?v=yLLWmdyfk-U[/video]


The CATO:
[video=youtube;9LnYXoHYizY]https://www.youtube.com/watch?v=9LnYXoHYizY[/video]

 

[REK]

The second video doesn't look like a CATO to me. Seems more like a premature ejection. Do you have pictures of the destroyed parts?

 

[Yoehahn]

The second video doesn't look like a CATO to me. Seems more like a premature ejection. Do you have pictures of the destroyed parts?

That's exactly what happened, the flame from the motor bypassed the delay element and lit the ejection charge before burnout