Ideal technique for packing Shock Cord and Parachute

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KenECoyote said:
Hi Purkeypilot,

As you can see, ask and you can get a dozen different answers! :wink:

My opinion is that since you have a 12 pack of Alphas, just use the chutes that came with them and try following the directions provided first, then when something goes wrong, try it a bit differently...heck, you have lots of replacements! Also when you're starting, it's great to learn through your own experiences to prepare you as you move to bigger things. However, I still recommend at least unfurling the chutes first...don't just stick them into the rocket as they come folded since they may well remain the same way. ;) Also others may disagree, but in general, I'll assume the manufacturer has some of the best advice on how to fly their rocket (note that this definitely isn't always the case), so I'll usually follow the directions first and then try to improve or fix next.

FWIW - I flew a lot of Estes plastic chute rockets in the winter on a frozen lake (often snow covered) and I think that's some of the worst conditions for plastic chutes...freezing temps and high humidity and so my earlier advice comes from a lot of launches in those conditions with stock Estes chutes.

Good luck and enjoy launching your Alphas!
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+1 Use as instructed, should have lots of great flights. That being said I don't use plastic on anything, Top Flight thin mil chutes on all LPR/MPR up to what their 30 inch chutes can bring down.
 
Can I use 550 nylon paracord to secure my NC to a quick link instead of Kevlar? This is for a PS II kit.
 
noffie79 said:
Can I use 550 nylon paracord to secure my NC to a quick link instead of Kevlar? This is for a PS II kit.
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You can use nylon, and many do, but the down side is that heat can degrade the performance of the nylon. So it can work but it may need to be replaced after x number of flights.

Greg
 
So, I think I'm going to pick up one or two Top Flight Thin Mill parachutes. I'm considering using the 9" for my LPRs that weigh less than 2oz. On Top Flight's website, under the "Descent" tab, it says that they recommend a decent rate between 17-22 FPS (crazy, as that is 9-15 Gs, though I guess that's not much when you're talking 1 oz.). I'm assuming that their chart is specifying weight ranges for each size that will keep it within that recommended descent range (1-2 oz. for 9" will result in 17-22 FPS)?
 
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I try to target 15-18 fps descent rate typically. A lot depends on what you're landing on - for me, its typically a planted field. Carrots, soy beans, wheat, etc and tilled soil. That makes for a softish landing, and the descent rate minimizes the walk. However, if you're landing on a harder surface (dry dirt, lake bed, concrete), you'll want to slow it up a bit and allow for more time in chasing.
 
EXPjawa said:
I try to target 15-18 fps descent rate typically. A lot depends on what you're landing on - for me, its typically a planted field. Carrots, soy beans, wheat, etc and tilled soil. That makes for a softish landing, and the descent rate minimizes the walk. However, if you're landing on a harder surface (dry dirt, lake bed, concrete), you'll want to slow it up a bit and allow for more time in chasing.
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I understand, it completely makes sense. I'm ask mainly because I'm trying to to make smaller what I'm puttin' in my <1" BTs :) Also, this time of year in the Southwest, it's hard to get a day with calm wind, and I want to keep the recovery area somewhat smallish if I can without breaking something, haha!
 
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To help understand descent rates, free fall distance helps. That is to say, if your rocket was falling without a recovery device from a predetermined height, the velocity at contact with the surface would equal that descent rate.

Your rocket falling from a height of 3'0.9/16" will simulate a 14 fps rate of descent.

Your rocket falling from a height of 4'5.7/8" will simulate a 17 fps rate of descent.

Your rocket falling from a height of 7'6.1/4" will simulate a 22 fps rate of descent.

Greg
 
I'd like to do fancy wraps but the wind (and ceiling fans) don't allow me. I fold my LP parachutes (everything I do is LP) in halves from Batman to smaller pizza slices, then fold that in half and wrap the shroud lines around it. Then I wrap the shock cord around the 'chute in the opposite direction. At ejection, the shock cord quickly unwraps the shroud lines and the 'chute deploys immediately.
 
Kirk G said:
I have been told that this simple, basic snap and swivel above will tend to pull apart if deployed too fast. I have been told you want a slightly different style, that will pull tighter onto itself under load, rather than spring the clip and loose the chute completely. I can't recall the NAME of this type of swivel for the life of me.
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You have been told correctly. I re-learned that lesson not too long ago on an Estes Stratocruiser. Beautiful flight up, not so good coming down.
 
Then, what does this other style look like? I've been in the habit of crimping these closed once I've installed them. So far, I've probably used them on 50 or so launches without issue...
 
I'll have to check that out when I get home - apparently Bass Pro Shops website is blocked here at work because they sell guns... :rolleyes:
 
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I use this type (wire only). I've had every other type fail but this style. There are several different types of wire only ones, I've used most of them, and they all work about as well. The safety pin style, not so much. Sooner or later, crimped or not, the metal fold fails, usually when your rocket is in a position to loose altitude un-gracefully.

https://www.ebay.com/itm/Fishing-Sw...lid-03-/271931895390?var=&hash=item3f50676e5e
 
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I used to use snap swivels, but had a couple pull apart from the force of deployment. But attaching the chute to the nose cone without doesn't have to be permanent: collect all the shroud lines together so their ends form a collection of loops. Insert the collection through the eye or nose cone attachment point, and slip the chute through the collection of loops. When you pull it tight, the parachute is firmly attached to the nose cone. If you need to remove it, simply loosen the shroud lines and slip the chute back through the loops. Changing out a chute or streamer that has a loop at the end is quick and easy.

As for packing the shock cord, one idea I have heard but haven't yet tried came from Tim VanMilligan at Apogee - he uses a crochet hook to "crochet" the shock cord into a short bundle (this works best with Kevlar thread). At deployment, the crocheted shock cord unravels with enough friction to cushion the ejection. He has a video on the Apogee site showing how he does this.
 
Bat-mite said:
Just about every rocket dealer out there sells heavy duty swivels. Why is everyone using fishing swivels?

https://rocketrywarehouse.com/advan...Csid=79de7c537471e0514d2c685dea825fb9&x=0&y=0

https://cart.amwprox.com/index.php?...category&virtuemart_category_id=29&Itemid=435

https://giantleaprocketry.com/products/components_recovery.aspx#Swivels

https://www.wildmanrocketry.com/ProductDetail.aspx?product=1133
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You don't actually think that these are purpose built ROCKET toys, do you? Wal Mart "Fishing" swivels work just fine for most LPR, and if you do some size and load test comparisons online (either on ebay or a retailer), you'll find you can make your rocket dollar go a LOT further with the same spec "fishing" swivel for MPR/HPR. That or you'll spend the same money, but actually have twice or more as much product! Heck, some of the web sites you posted even give you the size, but I note that their prices vary WILDLEY for the same item. For the price that one of them is showing, I recently got over a dozen of a better spec (but same physical size), shipped to my door. :)
 
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Banzai88 said:
You don't actually think that these are purpose built ROCKET toys, do you? Wal Mart "Fishing" swivels work just fine for most LPR, and if you do some size and load test comparisons online (either on ebay or a retailer), you'll find you can make your rocket dollar go a LOT further with the same spec "fishing" swivel for MPR/HPR. That or you'll spend the same money, but actually have twice or more as much product! Heck, some of the web sites you posted even give you the size, but I note that their prices vary WILDLEY for the same item. For the price that one of them is showing, I recently got over a dozen of a better spec (but same physical size), shipped to my door. :)
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Is there any way you can post a link to something you've used for MPR?
 
Banzai88 said:
You don't actually think that these are purpose built ROCKET toys, do you? Wal Mart "Fishing" swivels work just fine for most LPR, and if you do some size and load test comparisons online (either on ebay or a retailer), you'll find you can make your rocket dollar go a LOT further with the same spec "fishing" swivel for MPR/HPR. That or you'll spend the same money, but actually have twice or more as much product! Heck, some of the web sites you posted even give you the size, but I note that their prices vary WILDLEY for the same item. For the price that one of them is showing, I recently got over a dozen of a better spec (but same physical size), shipped to my door. :)
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Reminds me of a time when I made a WW II battle scene with a 4' X 8' sheet of polystyrene from Home depot for the same price of a 1' x 2' sheet of HOBBY FOAM at Staples. Look how much more I got because I didn't buy it in a cute plastic bag stapled with a colorful tag with the label "Hobby Foam" attached to it.
Some people want their genuine "ROCKET SWIVELS", not fishing swivels because their rockets shouldn't deserve anything less.
 
There are 2 generic types of fishing swivels: snap swivels (below left) and closed end swivels (below right).

snap fishing swivel.jpg closed end swivel_600_l.jpg

The snap swivel (left photo) has two problems: the snap wire can pull out under shock load and the 2 snap pin ends can snag your shroud lines. I don't recommend using them for rocketry. They are also available without the snap fitting (on the right side of the swivel in the picture) which is a regular closed end swivel.

The closed end swivels (right photo) are rated commercial fishing swivels. They do not have anything to snag parachute line and they won't open up below their rated load.

Snap swivels (without the snap portion) are adequate for smaller model rockets, especially those with plastic chutes. Mid and high power rockets should use the larger swivels shown below with test load ratings (Note: other manufacturers make them up the 12/0 size.)


50pcs-rolling-swivel-connector-solid-rings.jpg

These swivels are made from brass, steel or stainless steel. The brass and steel versions are frequently chrome or nickel plated to increase corrosion resistance. The stainless steel or the plated version of the brass and steel versions are preferred because of the corrosive nature of the black powder ejection charges.

The rating for fishing tackle has a design factor of 1. A 1500 pound test means the swivel or line will not break when a 1500 pound load is applied, however it could break if the load is 5% higher. IMO a single deployment rocket should have a recovery system rated for 100 G (+/- 5 seconds off apogee), so you swivel should be rated for 100 times the rocket weight. For dual deployment the rating drops to 40 G (64 fps delta v at sea level) differential descent rate or less when using a main parachute deployment retarding system such as a slider.

Bob

Thanks Greg. Fixed.
 
bobkrech said:
There are 2 generic types of fishing swivels: snap swivels (below left) and closed end swivels (below right)...
Click to expand...

Hey Bob, those first two links in your post aren't working for me. Are they good on your end?

Greg
 
Another thing: when the others say they wrap the lines around the chute you should be rolling the shroud lines, not winding them on. Winding the lines introduce a twist into the lines. Rolling the lines around the chute avoids this problem And I have never had a chute foul up in deployment ...unless the dreaded ejection charge bypass happens and you weld the chute together :p
 

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