Shopping for Kevlar cord

rodel: ahh I'm not trying to be a smart butt, but why don't you just call them on their

1-800 number and ask? Thats what I would do.... 800-915-2320 It appears the 2oz-8oz is the weight of the kevlar on the spool Tex size means the higher the number the heavier the thread..

let us know what you find out... shockie B)

Joel

Mile High Rockets

sells 120 lb Kevlar cord, 10 ft for $2.50. NO shipping or handling charge. No minimum order.

They also sell some great stuff that I haven't seen anybody else carry: Kevlar-wrapped elastic. All the strength and fire resistance of Kevlar, with the stretchiness of elastic.

I've ordered from them a couple times, and their customer service is the best I've ever seen -- even better than Balsa Machining Service, whom I consider top-rate.

-- Bob Cox

This reminds me of an idea I head for a "shock absorber" that would actually absorb shock in a recovery harness:

There are "energy-absorbing" foam rubber materials (I've encountered the material, under the brand name of "Ensolite", used by backpackers for a thin but comfortable camp mattress) that can be compressed rapidly by an applied force, but rebound relatively slowly (few tenths of a second). Take a long cylinder of this material, and put it inside a tubular braid of Kevlar, such that pulling lengthwise on the braid will compress the foam radially (like a "Chinese finger puzzle").

This assembly would provide a certain amount of "give" to a sudden tension load, but would absorb the energy (instead of springing back like nylon).

Thoughts, anyone?

-dave w

Interesting idea. If I am visualizing it correctly, your device would be similar in principle to the shock absorber used on dog chains, but instead of a spring, you're using a foam cylinder. Any concern with the Kevlar cutting the foam? Or ejection charge damage due to heat/particles?

Mark Simpson NAR 71503 Level II God Bless our peacekeepers

Good point, it didn't even cross my mind. I'm not sure I would know what to ask. The bigger size #'s represent larger diameter thread, but I don't know what diameter I need. My plastic ruler only has 1/16" marks on it and the Quest cord is "a lot" smaller than that ;)

Also, I kind of assume that phone order jockeys are not able to provide much rocketry related advice.

I was hoping the collective wisdom of rmr would be able to pick one out of the lineup, but *all* of the responses so far have pointed in another direction. This means that A) none of the products on the site would work, B) there's not enough information to make a recommendation, or C) it's a small hobby, and we expect you to support the little guy.

I think I will call and ask if it's coated or non-coated and what they mean by "bonded".

Ahh.. the magic words: "No S&H, No minimum". I didn't flinch at the $17 S&H charge I paid for my previous internet order, but that was 15 lbs. of supplies. In this case what I want could quite literally be stuffed in an envelope and mailed on a stamp (or two).

Thanks for that link, I believe that one's the winner. I might even pick up a pack of paratroopers :)

Test it numerically and put it on rocketmaterials.org?

david: you might want to take a look at a material called Sorbothane.....this is a energy absorbing polyurethane foam

is very useful as a padding in egglofters.......

available at mcmaster-carr as is evrything else in the known universe....

shockie B)

For small quantities of kevlar, het it from Pratt, ASP, or APogee as others have said. For large quantities on spools, I get mine from kite companies like

or when they have it surplus from Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!