If you ever come across a single-line kite flier using Spectra, you can bet they are up to something interesting, like setting altitude records! Or perhaps they just like the low weight of this material. Very large kites need quite a weighty and bulky spool of line otherwise.
Are you ready for some concentrated info on Spectra line? After digging around a little, some interesting facts popped up.
Just to be different, I've decided to use a Question / Answer format to present it all...
When the weather's good and you have the time, it's great to get out with a kite or 3. But what about on bad weather days? Then it's time to pull out...
"Kites Up!" - my downloadable kite-flying board game! Apart from towing indoor kites, doing a spot of imaginary flying is the next best thing :-)
Q: What's the difference between Spectra and Dyneema?
A: Not a lot! Which is why you have probably heard both terms used in similar kiting contexts. Confusing.
The 2 materials have slightly different molecular structures, which explains why Dyneema tends to wear a bit less. More importantly for multi-line kite fliers though, is the fact that at 3%, Spectra has about half the stretch of Dyneema. For single line flying, a bit of stretch can be handy for lessening the impact of sudden changes in line tension on the kite's frame.
Dyneema (c) is a registered trade name of the Dutch company DSM Dyneema. This material is much more popular in Europe than in the rest of the world.
Q: What is Spectra?
A: Spectra is a trade-name for a very high molecular
density form of polyethylene. Like other synthetic materials, it is made
in other forms beside long flexible line. Like bullet-proof vests!
Polyethylene, by the way, is the most widely used plastic on the planet.
Think 'plastic bags'.
In Spectra, the very long chains of molecules are aligned
which gives the material its very low stretch and high strength. In
fact, the strength-to-weight ratio is more than 10 times better than
Spectra kite line sold online is often of a length suited to sport kites (around 200 feet). The idea is to buy a sleeving kit as well and hence save some money. Putting knots in Spectra without sleeving that area first is not recommended! Many line sets now come with pre-sewn loops rather than requiring sleeving and knotting .
Q: How does Spectra compare with other kite line materials?
A: It is more expensive than most other line materials. Such as cotton and nylon. For a given strength, it is much thinner and lighter
than the other commonly used line materials. That explains why it has
been used for altitude record attempts! In fact, Spectra is about 1/3
the diameter of nylon line of the same breaking strain.
On top of this, Spectra has very low stretch, which is
important for flying steerable multi-line kites. In fact, it has roughly half the stretch of comparable Dyneema line. As for Dacron and nylon, there's no comparison :-)
You might have heard of Kevlar - a stronger line material than nylon or Dacron. However, Spectra is up to 40% stronger than Kevlar. Kevlar is quite abrasive and will rapidly saw through other types of material if lines are crossed. Hence don't use this material for single-line flying if you value your friendships on the flying field :-|
Q: When was Spectra invented?
A: Gel-spun polyethylene was invented by DSM High
Performance Fibres of Holland in the 1990s. At that time, the company
called the material Dyneema. It was later licensed to Allied Signal in
the U.S. and Toyobo in Japan. Dyneema is very similar to Spectra, and is
used a lot with paragliders. Spectra is the trade-name used by Allied
for its version of the material.
Q: How is Spectra kite line made?
A: Gel-spun, that's how. OK, I'd never heard of that
either... While the hot polymer is still in a gel state, it's forced
through a rotating spinneret to form individual strands which bond
together as they cool. After this the strands pass through an air-drying
and cooling stage before being cooled even more in a liquid bath.
It's no coincidence that spiders spin their incredibly strong web material the same way. Man copies nature.
Q: Who makes Spectra kite line?
Spectra is the trade-name for polyethylene kite line
coming from Allied Signal, a U.S. manufacturer. Actually, the name
'Spectra' is a registered trademark for the material, held by Honeywell
International. This company was known as Honeywell Incorporated before
being bought and re-named by Allied in 1999.
Q: Does Spectra have any special properties?
- It floats on water! That's more of interest to fishermen rather than kite-fliers of course.
- It has a rather low melting point. 147°C (297°F) to be
precise, which is not a lot hotter than boiling water! For this reason,
it must be kept well away from lines of other types while in the air. A
back and forth sawing action by the other line will soon friction-heat
the Spectra to the point of failure. Bye-bye kite!
- It is naturally very slippery, which multi-line fliers love since crossed lines don't inhibit the control of the kite.
- It is susceptible to 'creep', meaning it will very slowly get longer
if it is held under continuous heavy tension. Kite fliers would not
notice this, I'm pretty sure, as far as flying lines go. Bridle lines could be another matter though, where relative lengths are important.
Hope you found some of this info on Spectra kite line interesting, useful or even both!
As mentioned earlier, there's another alternative to towing indoor kites if it's just not possible to fly outdoors...
"Kites Up!" is my downloadable board game. It's a PDF file which has all the documentation for the game plus images for all the components. Tokens, cards, the board itself and so on. Anyway, just click that link to see more info :-)