12 grams may seem excessive on a 6" airframe, but it depends on the length of the bay and as I recall Conway's bird was a bit long. The UprOar project, a 7.5" project with an inner airframe of 6"" and it used 13.5 grams as I recall for main deployment - confined in 5/8" or 3/4" surgical tubing and that was not too much. The chute bay was about 48" long as I recall. JW may be able to comment here - I can't recall or find my old notes. Now we did have concerns about binding during separation since that wasn't an all-composite bird.

There you go, Chris! To each his own. YouWarren M. were not there to see my L3, lessons learned and a perflect flight! We are all brothers in this.

12 grams may seem excessive on a 6" airframe, but it depends on the length of the bay and as I recall Conway's bird was a bit long. The UprOar project, a 7.5" project with an inner airframe of 6"" and it used 13.5 grams as I recall for main deployment - confined in 5/8" or 3/4" surgical tubing and that was not too much. The chute bay was about 48" long as I recall. JW may be able to comment here - I can't recall or find my old notes. Now we did have concerns about binding during separation since that wasn't an all-composite bird.

Yep - that's why I said that it depends on the rocket, and I was assuming a fairly standard 6 incher. On a longer or heavier rocket than usual, more of a charge will be needed.

Well, JW, I agree with you on LONG shock cords, my L3 100 foot can attest to that. Although this guy, JW, doesn't use masking tape to reef the Kevlar, he uses electrical tape! I have yet to use latex glove fingers--as many in this club do, but that seems reasonable for highest of altitudes, and lower.

1.) Latex glove fingers will NOT work at really high altitudes... note that this was tried here http://www.wimpyrockets.com/page16.html. It is clean and tidy and all, but it doesn't hold the pressure long enough. Tony2 verified this in the chamber he built.

2.) I do indeed reef every few folds with electrical tape... at least on the bigger rockets. It would stand to reason that this would absorb the energy more, as it is harder to break. As you will see in the ground test, it works splendidly. I aways sorta bite my lip when I do this - and it always works!

JW

Yep..that's what I do too.

Tony

Personally I'm a masking tape Z-fold guy...1 layer where I want it to break first, then 2, then 3, then 4... in 4 bundles. Has worked well so far. I use masking tape because it is cheap and biodegradable.

I think this has become one of the best threads I have seen here in a long time!

Thanks for the pic Tony. Warren, can you explain the "z-fold" a bit please? This is great information guys and I really appreciate it!

the z fold is like what you see but laying flat going back and forth in a z like fashion. It is easy to do with the nylon cord that a lot of us use and also the Kevlar flat or tubular that a lot of us also use. It looks neat and deploys cleanly. Just bundling the cord up and taping it you have more of a chance of tangling. These methods not only help in a cleaner slower deployment but also helps make things easier to pack and fit into your airframe.

Here is a couple of pictures of Z-fold

OMG, I recognize that fixture. Z folds or taped bundles or carpenters chaining, whatever you want to call it, is like adding elasticity to an otherwise more rigid and finite length of shockcord.

That is Z folding extreme! I remember that fixture. Doug likes making things to make things easier. I think he just likes making things. 🙂

Holy crud, Doug! No wonder your rockets always deploy perfectly. Bret, you couldn't have had a better display.

Since the pictures were taken, I have moved to masking tape instead of the electrical tape. I'm more lazy than environmental and cutting all those little pieces of tape was too much work. I got an automatic tape dispenser from McMaster that measures and cuts the pieces to the same length. It was kind of costly but saved a lot of time taping all those wraps. It is even battery operated for the field.

Doug

Exactly what I'm talking about - except that I wrap the packets in different # of layers - one packet with one layer, then 2, then 3, etc. That way they pull apart in the order I want to prevent tangling.

Warren