What's happening with high altitude kite fying

Hello Rocketeers,

Bob Moore here. Got a message from this forum that long time no hear from me and what have I been up to? Well, in September 2014 my team broke the World altitude record for a single kite with a flight to 16,009 feet above ground level. This has now been certified by Guinness World Records, The Australian Book Of Records, the American Kitefliers Association and the Australian Kitefliers Society. This was the culmination of 10 years of intermittent attempts under the conditions provided by CASA.
After a break of 2 years we will be heading back to Cable Downs, a 50,000 acre sheep station northwest of Cobar in Western NSW. We may attempt to up the record to 20,000 ft plus and/or trial a train of smaller 4 kites to 20,000 ft in preparation for an attempt on the outright record for a train of kites to 40,000 ft. In the mean time I am building and testing various DT delta kites on local fields to trial different enhancements to the design to improve lift, durability and increasing the upper wind range.
The cross over interest between my kite flying and rocketry is GPS telemetry, data logging and to a lesser extent batteries. I have had some dialogue with the PICO balloonists that track Mylar party balloons around the world. There tracking tech is interesting and for me the batteries are my interest. Their balloons are flying around the 9,000 metre mark.
https://picospace.net/?p=1050
https://www.kitesite.com.au/kiterecord/september_2014.html
[video=youtube;IG_Y9ESbS4c]https://www.youtube.com/watch?v=IG_Y9ESbS4c[/video]

Bob

Very cool! Thanks for the report!

"flying"
"frying"
or "Fying"?:wink:

Kirk G said:

"flying"
"frying"
or "Fying"?:wink:

Click to expand...

Yeah, flying can be frying if it's really hot or can be fying if I'm from Japan or China.
The latest news is my team is heading west to our flying site in late September 2016. We will be testing a train of 4 medium kites up to 20,000 ft if conditions are right. Our GPSFlight telemetry has died and we will be using either the Tragic Little Aerospace or Big Red Bee GPS telemetry, both of which were developed for rockets by rocketeers in the USA. The only question is whether these units can transmit data reliable over 10 km. We will be using a Yagi receiving antenna which was good to 30+ km with the GPSFlight telemetry. Later, I hope to develop some mechatronics with a Guy in the Czech Republic and some of this stuff is already developed for quad copters.

Bob Moore

That is pretty awesome. {stupid question deleted }

Maybe it's Christmas?

Kirk G said:

"flying"
"frying"
or "Fying"?:wink:

Click to expand...

"No L"

Well, I've decided I could built a kite (not as good as the OPs, but still a kite). However, that winch system blew my mind.

I've looked over your site but possibly missed it, How much does the 12km of line weigh?
Are there rules in place restricting the use of anything to help support the line?
I would have thought that you would be required to have some sort of highly visible marker at set distances along the line.

I just realised why I haven't been getting forum messages. It's been going to the spam folder. Doh!
Somehow I missed this reply and it is over 2 years old but anyway I’ll update on high altitude kites. I had hoped to do some more flying from the Cable Downs site near Cobar in western NSW, Australia. Firstly the new property owner declined to respond to requests for further flights from his air strip. I then made some preliminary inquiries for permission to fly from a national park, 80 km to the north east of the record site. However, I also became unwell and postpone all kite activities. A few months ago I started to think again about either increasing the single kite record to 20,000 ft. + or a test train of medium kites to a similar altitude. The test train would consist of 4 x 4 sq. metre DT deltas, the same design as the record kite. The ultimate goal would be a train of 4 x 12 sq. metre kites to 40,000 ft. or a least surpassing the 1919 record of 31,955 ft.

The winch wouldn’t need to be upgraded for a 20,000 ft. flight but the kite needs some mods to improve lift. That involves replacing some of the fiberglass spars with carbon fiber. For the test train flights I would need to add a second motor to cater for increases in line tension from 54 kg to 70 kg.

For a crack at the outright record for a train of kites, the winch would need a major upgrade in power and running gear. The line I used over the 12 years of high altitude flights is still in good condition but I have a large quantity of Dyneema 78 line in storage which was donated by DSM Dyneema in Holland. The Dyneema I used on the record flight was 6,000 metres of 134 kg line from Amika in Taiwan. It is very high quality line made from fibres manufactured under license by Toyobo in Japan. The bottom half of the line was 6,400 metres of 159 kg Dyneema from France. The 134 kg top line was 0.7 – 0.75 mm diameter under tension. The 159 kg line is 0.85 – 0.9 mm under tension. Both are hollow braids with 8 strands made of (Dyneema 78) micro fibres. The hollow braided structure enables spliced joins which eliminates the need or knots. Dyneema has a specific gravity of 0.97 so floats on water. The 134 kg line weighs about 350 grams/1,000 metres and the 159 kg line, about 400 grams/1,000 metres. The total line weight was 4,660 grams. The biggest resistive force on the kite is line drag from wind resistance and the second most important is line weight. Line properties was one of the most important issues and I spent months finding the best lines. Drag,weight and power, the same issues for rocketeers, although at a much lower speed!

Bob

It's a small world. I read a bunch of stuff on your other web presences related to my quest for parachute materials.

I have the guys at work half convinced to fly an extremely high altitude kite project, based on how cool your projects are.

If I wanted to purchase some line similar to what you use, where would you suggest I look? Currently I have ~100m of Liros DC000-0161-228 0.83mm / 175 daN to play with.

Fascinating stuff, thanks so much for the inspiration.

In 2004 I purchased 200 lb line from Innotex in the USA. They manufacture braided ropes and lines including UHMWPE (Spectra 2000). I purchased 10,000 metres on 1,000 metre spools. This line was used for my initial test flights and is good quality but I decided to increase the safe margin between between actual line tension measured on field and the claimed breaking strength. In 2004 this line was $1,500 Australian or $150 per 1,000 metre spool landed.
In 2005 I purchased 10,000 metres of 300 lb Dyneema SK 78 from Amika in Taiwan. This line has proved to be exceptional quality and has been used in all series of record attempts from 2005 to 2014. I payed $1,300 landed or 13 cents/metre. Amika appears to have gone out of business which is a pity.
The lower half of the line I used to set the world record was 6,400 metres 350 lb SK 78 Dyneema made by Cousin-Trestec in France. This line was supplied under sponsorship from DSM Dyneema in Holland and was part of a 26,000 package of varies lines including 6,400 metres of 180 lb SK 78, 6,200 metres 250 lb, 6,400 metres 350 lb, 6,600 metres 550 lb. In my opinion Cousin-Trestec lines are the highest quality lines in the World but there are others that are up there.
These lines, irrespective of whether they are made from Spectra of Dyneema fibres are the strongest and lightest in the world. The gel spinning process that forms these fibres was developed and patented by DSM Dyneema in Holland. There are two other companies who are licensed to use this process. Honeywell in the USA makes these fibres and calls their product Spectra. They name their fibres and products with a numerical term such as Spectra 2,000 and Dyneema SK 78 to define the version and strength. They have developed stronger versions over time and the latest version is always the most expensive.
The other company was Toyobo in Japan who retained the Dyneema name for their fibres. The Amika line I purchased in 2005 was made with Dyneema fibres from Toyobo. Last year they ended there licence agreement with DSM Dyneema and have moved on to produce their own brand of fibres. I requested sponsorship 2 years ago but although they didn't rule it out, said they couldn't consider my request until they had fully developed their braided products.

Another line manufacturer I have contact with is Twinline in the USA. That company makes braided ropes, cords and lines. The owner is John Kiker who is a very nice fellow and is interested in kites and similar hobbies. He sponsored Richard Crawford's high altitude attempts and some images can be seen on the Twinline web site.

I had interest from another small manufacturer in New Zealand, Tasline. Although Kees Van Luik mainly produced lines for the fishing industry, he custom made some sample lines for up to 800 lbs. Very nice quality using Spectra fibres. He was prepared to sponsor my high altitude flights with line supply but this is on hold. The lines are the most expensive part of high altitude flying by far.

Why are these UHMWPE lines so good? The fibres are very small diameter (micro fibres) and are produced by a pultruding process of spinning and pulling hot molten UHMWPE (melted special polyethylene formula) through spinnerets and through cold water, much like a spider spins web, apart from the water. I have read that this material is related to plastic shopping bags. The molecules are aligned in this process to form very long and extremely strong chains of molecules with high bond strengths. The fibres have a specific gravity of 0.97 so the line made from these fibres floats on water.

The 300 lb Amika Dyneema has a diameter of between 0.7 and 0.8 mm depending if it is under tension or not. The relationship between diameter and strength is not linear as the strength is directly proportional to the cross sectional area. This is a function of Pi R squared. This is very important as larger kites can use much stronger lines but have a lower kite area to line drag ratio. In other words, double the kite size requires double the line strength but a line twice as strong is only 43 % larger in diameter. All these lines I have mentioned are what are called 8 ply braids or have 8 fibre bundles and are hollow braid. The hollow braid structure allows knot-less splicing which eliminates the need for knots which can weaken lines by up to 50%. The line is also very slipper, having a friction coefficient of 0.2 which makes it very difficult to hold a line under tension even with gloves. This presents a mechanical problem as well as the line needs to wrap around the winch drum at least 16 times to reduce the spooling tension to under 2 lbs. Any greater spooling tension will see excessive accumulated tension on the storage real and possible reel collapse but although the reels i use are solid core, the reel sides may spread.

One flaw with these UHMWPE lines is there low melting point of about 150 deg C. Line guide friction should be avoided. I use guide pulleys on my winch so there is no heat build up from friction on fixed guides.

I haven't mentioned lines from China. Avoid them as any purchases I've made or samples from China have resulted in anguish and very unhappy communications. I discarded 10,000 metres of brand new line the manufacturer called Dyneema but was 70 % of the strength of genuine Dyneema. I suspect they use cheaper Dacron fibres with the stronger fibres. The exception would be if you found an honest supplier who could guarantee their products but that is very hard IMO. Most of the lines made in China are fake, poor quality and rarely meet the standards set by DSM Dyneema or Honeywell Spectra.
Europe - https://www.cousin-trestec.com/en/
USA - https://www.twinline-usa.com/ Take a look at Richard Crawford's high altitude kite and he mentions line for altitude kites in his product usage.
Australia - Toyobo https://www.toyobo-global.com/seihin/dn/izanas/ (contact Toyobo to find out who are their line braiding partners) or Tasline in New Zealand https://www.tasline.co.nz/
Ebay has lots of low strength lines claimed to be Dyneema. I doubt that many are actually authorised or genuine Dyneema or Spectra. Very few lines over 200 lb

Bob Moore

Hrmm, so my sample is sk99, pre-stretched, heat-set, around 390 lbs if I'm not missing the point entirely.

But! It's probably the wrong type entirely as I believe it would have to be knotted / don't think it can be spliced.

Thanks again for all the good things to ponder.

Very cool! My wife thinks I'm nuts when I put together a train of 10 and have to tie it to my truck.

Kiting interest me too. I want to build a box kite to get to the 1500'-2000' range but I have zero idea what size to make the thing or what poundage I need for the line.

I figured I'd start on the smaller side and shoot for the 500' range first.

The product specs are being upgraded constantly but my detailed knowledge of Dyneema and Spectra braids is about 4 years old. Each time DSM brings out a stronger version of Dyneema, Honeywell responds with a stronger version of Spectra. These companies don't actually make ropes, cords or line, rather their manufacturing partners do. The line manufacturers make various spec braids and the details may change more rapidly than the fibres they' are made of.
The thinner braided lines like 80 lb fishing line, are 4 weave, lines over 100 lb are usually 8 weave and a few are 12 weave and up to 16 weave. For the same strength line but with more weaves, the line is slightly thinner. The more expensive lines are prestretched or bedded. My Amika 300 lb Dyneema SK 78 line was 0.85-0.9 mm thick from the factory. After several years of flying under tension and stretching out on a dry lake bed under high tension, the line is 0.75 mm thick. This is a 17% narrower so reduces the aero drag significantly. Stunt kite flyers are particularly interested in prestretched lines. Some lines are braided around a strand to fill the hollow braid (solid core) and this increases line strength for a slight increase in line diameter. It does prevent splicing joins which precludes it's use for my high altitude flying.
The fiber's product codes are something like this: Dyneema SK78, SK75, SK65, SK62, SK38 etc etc. I believe there is SK88 and now SK99. I think they choose those numbers because they have a ring to them for marketing purposes.
Spectra 900, 1,000, 2,000 and I don't know what else. Dyneema has some interesting applications for it's fiber including composites. I don't know if these composites are superior to carbon fiber.
An interesting side light to the high altitude flights was my inclusion on the consultants for the Ion Power Group. https://ionpowergroup.com/contactteam/ Their goal is to extract electricity from atmospheric ions. Who knows how all this could be related to rocketry? Some times knowledge is serendipitous.
Re rockets. Before fireworks were banned in my state (NSW Australia) we used to have rocket fights in the street. These rockets cost a penny and were about 30 cm long. Their maximum altitude was about 200 ft or so. We used to use a tube to launch them at each other when we were about 100 ft apart. With slight elevation they usually reached the target within 2 seconds or so. Pretty harmless unless hitting someone's eye which was unlikely. The bungers were a different story. The two penny bungers were about 8 cm long and 3 cm thick. They blew a few kid's finger's off and there were enough injuries from other fireworks for the authorities to ban the public sale of fireworks in all states except, for some strange reason, our national capitol, Canberra.

Bob Moore

You people (I was about to write guys but I don't know if there are any lady rocketeers) may be interested in my use of GPS telemetry. In 2004 I started my high altitude flights out in western NSW using a Garmin Geko hand held GPS which I put on-board the kite. I could only estimate the kite's altitude in real time by the amount line out, the kite's angle and the line droop. I used a catenary table which gave estimate of altitude and was accurate within 5%. In 2005 the record attempts began and I increased my inventory of GPS loggers to 3 Garmin handheld units plus started using theodolites in conjunction with accurately surveyed bench marks. The triangulation methods associated with the theodolites proved very difficult and impossible in cloud. I have included a chapter on theodolites on my website. In 2007 I first used GPS telemetry with the acquisition of a GPSFlight 900 MHz system. Very good features but very unreliable over the first 2 versions. The last one I obtained before the company died was more integrated with SMD components and the transmitter is still working but the receiver failed 2/3 of the way through the record flight.
I have the following and I summarise these units with a few words:
900 MHz means 902 -928 Mhz. some are spread spectrum but within the amatuer radio band in Australia
GPSFlight STXe 900 MHz. Good features with extra pins for temp and barometric altitude. Maxstream (now Digi) receiver failed. may be able to get a new one. Reported as 40 km with some estimates as much as 100 km line of sight.
BigRedBee 900 Mhz - Never tested on board but has failed with only back yard and battery tested. To be sent back for repair or replacement. Online report claims over 50 miles.
Tragic Little Aerospace - Never tested on board but still working on bench. Will test for range soon but some online reports claim over 30 km line of sight.
Eggfinder - One kit built late last year (not by me). Hand held LCD display and basic GPS telemetry transmitter. No reason why range should not be similar to BRB or TLA units. Purchased optional receiver to data log to laptop. I plan to purchase 2 other transmitters as backup providing the range tests exceed 20 km line of sight. Purchasers do require some electronics and soldering skills to assemble theses kits.
Data loggers are used as on-board backup for record verification and ground searches with the last known GPS telemetry position.
Garmin Geko - I've disassembled this to customise a battery pack to increase the duration. I need to make an insulated enclosure to keep it from -15 degree temperatures. I loke the Garmin devices because of the Mapsource software.
Garmin eTrex H x 3. A little bigger and cheaper than Geko but does the job as a ground search GPS for 3 team members.
Holux x 3 - Did the job as a backup logger when the GPSFlight system failed on the record flight.
Tripmate 852 - Works fine and power consumption as good if not better than the other data loggers. Hasn't been flight tested in low temperatures.
Canmore - A cheap logger off ebay. I haven't field tested it yet but works outside my workshop.
All these loggers interface with Windows 7/10 but I can't remember Bluetooth capabilities which would be good for Android and other hand held communication devices.
I like to use a Windows laptop on field as that is what I am used to. The only problem is the bright sunlight drowns the screen so I have to make a viewing enclosure. The same with the LCD receiver for the Eggfinder. Something that fits around the eyes and the shape of the face like some binoculars.
BigRedBee runs with Trimble Studio which is very comprehensive but has a steep learning curve. I found it best not to touch the default settings.
TLA uses U-centre which is a little less complex but again default and auto detect setting is best IMO.
The Eggfinder uses proprietary software in it's LCD tracker but the receiver laptop dongle van use a variety of Windows compatible software, eg mapsphere . I haven't tried it with others for data logging such as Trimble or Ublox u-center. There is a program called visual GPS which I have played with a little but have not come to any conclusion if it's good, bad or indifferent.
I have a lot to thank you Rocketeers as without your hobby and a few electronics gurus, I wouldn't have any affordable GPS Telemetry to stick on-board my kites or I would have to get someone to invent it.

Bob Moore

In return, thank -you- for these extensive, comprehensive, and long-duration comparisons.

Very handy to have reports on more than a few moments' experience.

Electronic of this type, especially those requiring custom enclosures, are relatively fragile. They won't last long in the field if they are not protected from rough handling. Pay attention to their housing, shock proofing, static resistance plus treat them with care and they should last for many years. Don't look after them and they will be lucky to pass one season. I'm reminding myself about this as well.

Bob Moore

Droceretik said:

Electronic of this type, especially those requiring custom enclosures, are relatively fragile. They won't last long in the field if they are not protected from rough handling. Pay attention to their housing, shock proofing, static resistance plus treat them with care and they should last for many years. Don't look after them and they will be lucky to pass one season. I'm reminding myself about this as well.

Bob Moore

Click to expand...

We like to regularly subject ours to high G-loads, so mounting and protection is something we're rather fond of as well

About the Chinese... From my observations as a teacher here, great strides have been made in their ability to distinguish and pronounce the letter "L" (though complex consonant clusters are still a PITA (example "world" which frequently sounds like "word"). They still have problems with the fricatives (namely the voiced and unvoiced "th" sound (as in "this" and "thick" respectively)) tending to pronounce it like an "s". So, "they" might sound like "say", and "mouth" frequently sounds like "mouse". The affricative (voiced palatal) sound of "j" as in "joy" is also a problem... "Usually" often sounds like "you rally" (note: this is not the "L" that is the problem).

The odd thing is, they have many of these sounds in their own language, but not as syllable final consonant sounds. Most Chinese syllables end in a vowel sound, necessitating the use of a schwa (the "uh" or "er" sound) at the end of words that end with a consonant sound.

Vowels are another problem all together.

FWIW, when you see Chinese words written in Pinyin (the western alphabet system), the "zh" is pronounced like a "j", "xi" is pronounced like "she", and "t" is more like our "d" (as in "duh", but not like "deep"), though "ts" is like very much like the sound in "tsunami".

You can see some detailed updates of progress towards some remote kite tests on my Facebook site. https://www.facebook.com/donate/307298369939345/
Sponsorship has reached $1,300 which I am very grateful for.
A sheep station owner has invited my team to do some testing on October 3rd, 4th, 5th and 6th. This is a 223,000 acre property, Bulgoo, 40 km South West of Cobar in western NSW, Australia. It's about 70 km SSW of our previous site at Cable Downs. We won't be going really high but enough to test the 3 GPS telemetry systems, a few kites, some new line and some winch mods. I have sponsorship from Toyobo in Japan with their IZANAS line. Toyobo actually made the Dyneema fibre which our record line was made from by Amika in Taiwan. They ended their agreement with DSM Dyneema in 2016 and developed their own fibre. They declined my request for sponsorship in 2016 but didn't rule it out. After I sold them a convincing story early this year to promote their new fibres, they agreed to supply Tasline in New Zealand with fibres to create some test lines. The fibres provided should be enough to make 7,000 metres (23,000 ft.) of various 8 weave test lines between 310 and 330 lbs. These lines will be between 0.8 and 0.85 mm in diameter, hollow braid. They are hollow to enable knotless slice joins. Knots weaken the line by up to 50% and at least 20%. Future sponsorship from Toyobo will involve provision of enough fibre to make at least 40,000 metres of line for the single kite record and 30,000 metres of higher strength line for the kite train record. That's a lot of line and could be valued at up to $15,000. The owner of Tasline will be making these lines to sponsor our records. This is very generous donation of his time, expertise and production facilities. The braiding production rate of an 8 carrier braid is about 6 metres/min. 40,000 meters would take about 5 days continuous running but probably would be done in 1,000 metre reels that I can easily be spliced later. That gives a lot more flexibility to fit a reel in between his production runs of fishing line.
I am building some new storage reels that will be 75% lighter than the solid core reels. This will reduce inertial sluggishness on acceleration and braking of the winch which can produce slack line between capstan and storage. Line damage and kite loss was partly caused by this flaw in 2005 and resulted in a lost kite and 3,000 metres of line.
I have a new sports camera that i will attach to the kite. I have another time lapse camera but it is a little big. I am adding some carbon fibre mods to the current kite design to increase power. If this results in significant increases in lift then I will incorporate these mods into a 30% bigger kite design which will get us to 25,000 ft. next year given favorable winds. Interestingly, my ophthalmic surgeon wants to visit us later this year at Bulgoo station as he runs an eye clinic at two remote townships nearby. Ironically the kites will be out of sight but I do have telescopes and binoculars.

Bob Moore

Some of you may have experience with the BigRedBee GPS telemetry. I mentioned above that it failed basically just sitting in my workshop cupboard with occasional testing out the back for battery duration and andonce for accuracy against government survey benchmarks. Probably less than 12 hours run time. Anyway, early this year I got it out and it had died. I sent it back to BRB and Greg Clarke was very kind to replace the major components free of charge even though it was well out of warranty (about 7 years!). All I had to pay was the $28 mail and it is as good as new. I am still puzzled why electronics would fail just sitting in a box inside a cupboard inside a workshop unless I carried a lot of static charges the last time I handled it. It could be that I zapped it with overvoltage when experimenting with different battery packs but I don't think so. I will give it an extensive test in October out west at our new site. I'll just use the included rechargeable LiPo pack for the time being. That pack is intended for rocketry where 4 hours duration is usually enough to do a ground search but is well short of the 14 hours required for a long kite flight in difficult conditions.

Bob Moore

My favourite bit: At about 1:12 into the video...notice the wind-destroyed EZ-Up in the background? Yep, there are lots of shared experiences between rocket and kite folk, and that is certainly one of them I guess.

Seriously though....congrats on the achievement, and thanks for posting here. Very interesting and cool.

s6

Cousin Letrec 16350 too much for this 56" x 136" DC ?

dhbarr said:

Cousin Letrec 16350 too much for this 56" x 136" DC ?

Click to expand...

Photo attached this time.

dhbarr said:

Photo attached this time.View attachment 388583

Click to expand...

Excellent kite and great graphics.
Bob Moore

I've always liked the French Military Kite... I've got a 9' Dual French Military kite design in the works. However, the pattern I was working on was tossed by someone at work, so I have to start over.

Like I said to Kitelines Magazine back in the 90's...

If your kite can't kill you... It's TOO SMALL!!!

It's a little hard to make out at the end of 1000ft of Twinline Spectra 200 against the LDRS38 sky :-D

Plenty of good exercise reeling in ~100ft while walking toward it, then dragging back straight overhead.

stealth6 said:

My favourite bit: At about 1:12 into the video...notice the wind-destroyed EZ-Up in the background? Yep, there are lots of shared experiences between rocket and kite folk, and that is certainly one of them I guess.

Seriously though....congrats on the achievement, and thanks for posting here. Very interesting and cool.

s6

Click to expand...

I also had an E-Z Up destroyed by the wind. And was at a rocket launch, no less.
I'm not sure how big my two line stunt kite is, may have to post a photo of it.
Keep up the amazing work!!

Droceretik said:

I just realised why I haven't been getting forum messages. It's been going to the spam folder. Doh!
Somehow I missed this reply and it is over 2 years old but anyway I’ll update on high altitude kites. I had hoped to do some more flying from the Cable Downs site near Cobar in western NSW, Australia. Firstly the new property owner declined to respond to requests for further flights from his air strip. I then made some preliminary inquiries for permission to fly from a national park, 80 km to the north east of the record site. However, I also became unwell and postpone all kite activities. A few months ago I started to think again about either increasing the single kite record to 20,000 ft. + or a test train of medium kites to a similar altitude. The test train would consist of 4 x 4 sq. metre DT deltas, the same design as the record kite. The ultimate goal would be a train of 4 x 12 sq. metre kites to 40,000 ft. or a least surpassing the 1919 record of 31,955 ft.

The winch wouldn’t need to be upgraded for a 20,000 ft. flight but the kite needs some mods to improve lift. That involves replacing some of the fiberglass spars with carbon fiber. For the test train flights I would need to add a second motor to cater for increases in line tension from 54 kg to 70 kg.

For a crack at the outright record for a train of kites, the winch would need a major upgrade in power and running gear. The line I used over the 12 years of high altitude flights is still in good condition but I have a large quantity of Dyneema 78 line in storage which was donated by DSM Dyneema in Holland. The Dyneema I used on the record flight was 6,000 metres of 134 kg line from Amika in Taiwan. It is very high quality line made from fibres manufactured under license by Toyobo in Japan. The bottom half of the line was 6,400 metres of 159 kg Dyneema from France. The 134 kg top line was 0.7 – 0.75 mm diameter under tension. The 159 kg line is 0.85 – 0.9 mm under tension. Both are hollow braids with 8 strands made of (Dyneema 78) micro fibres. The hollow braided structure enables spliced joins which eliminates the need or knots. Dyneema has a specific gravity of 0.97 so floats on water. The 134 kg line weighs about 350 grams/1,000 metres and the 159 kg line, about 400 grams/1,000 metres. The total line weight was 4,660 grams. The biggest resistive force on the kite is line drag from wind resistance and the second most important is line weight. Line properties was one of the most important issues and I spent months finding the best lines. Drag,weight and power, the same issues for rocketeers, although at a much lower speed!

Bob

Click to expand...

Hey Bob, where can I get kite line? Can't find dyneema anywhere in bulk?