"Flex" pyro recovery hardware

[jderimig]

This post is an offshoot from the Goex BP thread. This is a recovery system I just test flew successfully at BALLS 29. Everything is in the nosecone, integrated altimeter board, gps, apogee "pushrod" and main chute line cutter. For apogee a tiny 1/8 gram charge of BP (or Pyrodex, or smokeless power) pushes a pushrod (not shown in pictures below) against a shelf in the airframe to push off the nose cone. Attached to the linecutter is the main chute in a drawstring bag which is released when it fires. Also only uses about 1/8g of gas generating powder. Powder is contained in both cases, will work in space.

 

[cerving]

Interesting. Are you doing HED? Do you need shear pins on the NC? Vents to prevent the NC from coming off at speed?

 

[jderimig]

Yes, one break at the NC. One shear pin on the NC to keep the pushrod seated against the charge.

 

[Kelly]

Would love to see more info and pics.
Are you concerned about the laundry hanging up on the 'shelf'?
How exactly does the linecutter free the chute from the drawstring bag?
How do you retain the push rod?
How fast does the NC come off, will it reliably pull out 'tight' laundry?
More details on the linecutter? It looks as though maybe that eye comes off when the linecutter fires?

 

[watheyak]

That is some outstanding outside-the-box thinking.

the more I look at the picture the more “cool factor” I see. Marsa squirrel-works has been busy!

 

[jderimig]

Are you concerned about the laundry hanging up on the 'shelf'?

Yes, that was a concern. The shelf is roughly contoured to minimize catchpoints.

How exactly does the linecutter free the chute from the drawstring bag?

The drawstring is a ziptie that gets cut by the line cutter. The drogue pull the bag off the chute and lets it inflate.

How do you retain the push rod?

The hole in the shelf above is lined with a sheet of rubber that attempts to hold the push rod.

How fast does the NC come off, will it reliably pull out 'tight' laundry?

About 15 ft/s on the ground test.

More details on the linecutter? It looks as though maybe that eye comes off when the linecutter fires?

The eyebolt is the attachment point for the harness, it stays on. It comes off for cleaning only.

 

[bobbyg23]

This is very interesting.

 

[Buckeye]

Very interesting, but you omitted the best part. Need details on the pushrod thingy!

 

[Kelly]

Ah, OK, you're using a drogue, that makes it a bit more clear. And so that hole in the eyebolt-rod is the linecutter?

I love that the BP residue - and flame - is entirely limited to the interior of the rods. No exposure of the body tube, chute, lines, or electronics whatsoever. No need for a chute protector.

 

[jderimig]

Very interesting, but you omitted the best part. Need details on the pushrod thingy!

Does this view help?

 

[jderimig]

Ah, OK, you're using a drogue, that makes it a bit more clear. And so that hole in the eyebolt-rod is the linecutter?

I love that the BP residue - and flame - is entirely limited to the interior of the rods. No exposure of the body tube, chute, lines, or electronics whatsoever. No need for a chute protector.

Yes and no need for ridiculously long harnesses.

 

[ChuckH]

This reminds me of the Z-Pard (zero pressure active recovery device) that was featured in Rockets magazine 15 or so years ago. I could probably dig up that issue if anyone is interested. Here's a thread about another implementation of that device.

https://www.rocketryforum.com/threads/z-pard-test-video.137084/

 

[FredA]

Sweet -- how high did the test flight go?
How did the GPS & Radio's do?
Is this a product or test bed?

 

[jderimig]

Sweet -- how high did the test flight go?
How did the GPS & Radio's do?
Is this a product or test bed?

Did 29K on a fast M. Everything worked. Could be a product now that it is proven (once...). Would do one more iteration likely to improve somethings. Probably go double thickness PCB as it doubles as the "sled".

 

[Worsaer]

Hey John, I like where this is going. I see what looks like your collaboration with James also. Looking forward to hearing and seeing more.

 

[jderimig]

Hey John, I like where this is going. I see what looks like your collaboration with James also. Looking forward to hearing and seeing more.

This was more of a "Frankenavionics" project with James to integrate known working solutions for this flight.. The new stuff we are working on will spin some heads, mine is still spinning. Had a successful test flight of that stuff at BALLS 29 in another rocket. Sorry for tease.

 

[Worsaer]

… Sorry for tease.

No apology needed! It’s refreshing to see product development in progrses.