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Large Streamers for HPR recovery
#1
I'm a big fan of streamers.  I use them all the time as apogee events for DD rockets, made a few of these for friends, but have recently been looking into them as primary recovery devices for L1-sized rockets.  Most, I've found, can accommodate a streamer large enough to bring them down at reasonable recovery speeds (I generally shoot for around 17 FPS).  Recovering under streamer definitely has an advantage over a chute --if in no other area, it's REAL easy to see and visually track.  

Problem is, there's damned few places one can purchase a durable streamer.  I know of one manufacturer with a line of them, but they aren't anywhere near large enough for true HPR recovery.  So, I figured I'd start making them. 

I'd considered mylar, like that which is used in the LPR rockets, but the stuff tends to rip--also, holds its folds extremely well... which is good to increase drag, if you have lateral folds, but if you have to vertically fold it to fit it in the recovery compartment, this is a problem.  I briefly considered Nomex, but it's expensive and difficult to find--and its primary advantage (heat resistance) is pretty well defeated unless one uses a Nomex thread as well--and that's even more difficult to find and more expensive than the material.  This led me back to nylon. 

I started with a 4" by 40", for LPR, because that's what I thought a streamer Had To Be... that the golden ratio was 10:1, because, Hell, that's what everyone uses, so it's gotta be right.  Turns out, I found I got better results if I went with a 12:1 L:W ratio rather than the 10:1.  In doing research on why it's 10:1, I discovered that ratio was from a paper published in the early 70's, and that ratio was recommended for PAPER streamers, not nylon.  The 6" version I made in both ratios gave me a slower descent rate without adding significant weight, so I adopted the 12:1 as my standard with this material. 

After a lot of trial and error, and figuring out not only how to make these well (and lighter, and less bulky), but also how to predict their descent rates at a given weight, and what tube they'd fit in and deploy well out of, at Red Glare 18 I recovered my G-force under a 24" by 24' streamer. It had flown on an H... 135, I think?  A little 29mm white motor.  I forget; I was more into the recovery than the motor on that flight, to be honest.

I figured that one predisposed to argument, or vehemently against streamers for HPR for reasons incomprehensible to me, might justifiably argue that the G-Force is not, truly, a HPR rocket, but rather a MPR with some HPR capabilities if modified for this purpose; that the stock-built G-force is made for G motors, thus the title of the kit.  While I would balk at this, and point out that most G-forces I've seen --indeed, most kits-- are modified to some degree to suit the flier's intent, there's no denying that, if built stock, it's supposed to take G motors.  So the Red Glare flight I'll consider a 95% of accomplishing the goal.

I have a nearly-stock Minie-Magg here (I added an Aeropack, and used epoxy in construction).  A couple of them, actually.  One's painted, even, and I did my L1 on it back in 09.  There's also a King Kraken I've got sitting around that's never flown on anything smaller than a H (mostly I's).  These, surely, qualify as L1 rockets, would you not agree?

Of course, they're a bit heavier than the G-force, as they use thick tubes, heavier nosecones, and plywood rings (and, in Maggie's case, fins).  I'm thinking a 30" x 30' for the King Kraken and  36" x 36' for the Magg.

As I'm making these for myself, I wondered... would anyone else be interested in using them, or, at least, learning more about them?





Later!

--Coop
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#2
Some photos...

   


This is the 18x18 streamer. Here, you can see one of the brass grommets I put in for tying or quick-clipping to the harness. I can recover something about 1.5 lb on this as primary, or up to about 20 lb as secondary, depending on how quick I want it down from apogee.

   

Here she is in a loose roll. You can also see here the tunnel I sew in to permit the harness to pass through the streamer.


   

There's the tunnel--and my left hand. Heh.

   

Here's the backside of the venture, showing the box around the grommet area, one of the grommets, and the tunnel.

   

Here's how I hem them--a double roll, so the raw fabric edge is encased inside. This is tedious and time consuming, particularly on the real big ones, but I prefer this look to the serger's thread loops.

   


Here's another one I made, loosely rolled and folded so I can weigh it to input into Rocksim. That's 306.8 grams. Care to guess this streamer's unfurled size?

Later!

--Coop
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