Kite Altitude World Record
Dyneema®, the world’s strongest fiber™
September 2012 - Wind, no Wind, Wind, Windier and Windiest.
One of the most frustrating and eventful weeks on Cable downs. My two boys, James and Andrew came up to observe and to keep the sheep station kid, Ethan company.
Mike, Mick and Roger arrived on Monday September 24th. Setting up the winch and base station took about 2 hours so it was about 11 am before we could launch and didn't leave much time to have a crack at the record, especially with some dead patches to negotiate. An 8 - 12 knot breeze was blowing from the south and we quickly ran the big white and black DT delta up to 4,000 ft. The new hydraulic tension gauge was wonderful, thanks to Doug La Rock. It showed that with moderate winds, line tension varied between 10 and 40 lbs, a lot less than I anticipated.
From 4,000 ft we struggled to make any progress and eventually we decided to retrieve the kite to adjust the bridle's angle of attack. Unfortunately, this put off any hopes of a record
Monday September 24th
These graphs were downloaded after return to Sydney and were not available at Cable Downs. The green line is the most important lthoughthe wind direction can have an effect on the ability to negotiate wind sheer.
A late start is usual on day one. Uunless the whole team is on the strip by 6am it is difficult to setup the base and be prepared for launch by 9am. With ideal winds from ground to record altitude it would take 4 hours to reach our target and 3 hours to retreave the kite. In marginal conditions up to 12 hours would be need for the entire flight.Unfortunately we were unable to capitalise on potentially good conditions due to the late start and line which proved to be the wrong grade. 450 lb line was supplied as 250 lb and while the breaking strength is not in itself a problem but the larger diameter causes excessive wind drag and to a lesser extent the extra weight contributed to line sag. This error in line selection was a major issue for the whole week and on one day in particular, may have prevented record altitude.
Other issues were the telemetry battery lasting due to incorrect charging and possible low temperatures causing Garmin GPS shutdown.
A major surprise was the La Rok tension gauge showing lower than expected line tension and the winch motor being overcome at 120 lbs tension.
The kite bridle setting was not giving sufficient pull nor a high flight angle on day one and this limited it's ability to power through some soft layers. it wasn't to mid afternoon that we retrieved the kite from a 4,500 ft maximum then relaunched after adjusting the angle of attack. By 4.30 pm the kite was back up high had gone beyond 5,000 ft but it was too late to try for anything higher and be down before last light.
Disappointing news was the reduction in balloon flights at the Cobar weather station to 3 days a week. This reduced our available wind data, effecting the flight strategies significantly. I understand this cost saving measure has been applied to many stations across Australia.
Tuesday 24th and Wednesday 25th September
Conditions were warm and mostly calm with light eastly to north easterly breezes, calm periods and thermals. The only flights possible were with medium deltas and a rok to 700 - 1000 ft. Mike and Mick amused themselves flying a Platz glider near the wool shed. The calm was a contrast to the high winds and storms over the next 3 days.
The graphs (left) are from the Australian Atmospheric Soundings site, a service for glider pilots. The data is fed from the Australian Bureau of Meteorology balloon sonde flights. Unfortunately cost cutting has reduced these flights at Cobar to Monday, Wednesday and Friday. If the auto balloon launch fails then often the launch is not repeated. Occasionally there will be an extra flight if a significant weather event is occuring. This happended on September 26 with an additional flight at 8am(see 26th UTC 00Z) You can see why it was near impossible to launch the big kite because of winds in the 3 - 6 knot range from ground to 6,000 ft. 25 hours later (below) winds were better but still not ideal.
Friday September 27th
The times at the top of the graphs are in UTC or 10 hours before local times. 23Z on 26th september is actually 10 hours later or 9am on 27th Sept. The sounding gives a snapshot of conditions and so it although it is accurate at that time, it may vary a lot within an hour or stay similar for many hours. The "vary a lot" could mean big low wind layers develop or there are increases in certain zones. The kite would probably struggle on the 27th at 7,500 - 10,000 ft then again at 14,000 - 15,000 ft. if these conditions shown on the graph remained static. They didn't but the kite struggled because the line was too thick and heavy for these light to moderate winds. The kite may have reached 13,000 ft but the telemetry stopped transmitting at 10,000 ft because the battery wasn't fully charged. I'll never know the true height because the backup Garmin unit also stopped recording at around 9,000 ft. These niggling issues with batteries are easily fixed but remain crutial for the record attempt to be properly recorded.
Friday September 28th
Refer to sounding of September 27th, 23Z. The wind went "off the dial" at 3,000 ft and we didn't have the benefit of weather station balloon data telephone reports. A strorm that came through also added to our problems. The kite was already distressed with wings bent back and not gaining any height. The tension gauge showed a constant 120 lbs which, surprisingly, was the limit of the winch motor's capacity. I had miscalculated the effect of a larger motor pulley (2.5" increased to 3"). I assumed the maximum to torque generated to equal 200 lb line pull. The motor will be upgraded to 1.5 hp from 1 hp. We were struggling to retrieve the kite because the winch only operated with enough torque at low rpm.
Consequently the storm squall line roared through with the kite still at 1,000 ft. It was ripped beyond repair and the only salvagable parts were the spars. The line was intact as it should be being 450 lbs and 1.5 km was recovered easily with no signs of damage. We retired to the wool shed to assemble another kite. We carry 1 spare assembled kite, 3 spar skins and spars on each record attempt. So we have a total of 5 record capable kites on every series plus 3 spar line sets, a backup motor, 3 sets of telemetry and 4 garmin GPS units. We also have a repair tools and spare spars. The telephone communications is a task in itself. We have a 4 meter mast and cabling to connect my Telstra 3g phone. It's mandatory that I contact airservices to open and close the zone at the start and finish of any flights.
Saturday September 29th
With the new kite we launched at 8am with high hopes. It seemed to be progressing well until 6,000 ft when high winds again cause the kite to stall. Through the theodolite it look distressed with folded back wings and the line tension again heading over 100 lbs. We persisted until mid afternoon when we decided to abort the attempt. Unfortunately Mike, Mick and Roger decided to return home as they had a kite festival to run and work committments.
The good conditions have again given way to dry soils, low dam levels and heading toward drought yet again. Farming requires a great deal of patience and skill to extract a decent living even from a property of 50,000 acres as is Cable Downs. Stock numbers were built from 600 in 2007 to over 1,000 in 2012 I believe. Without rain these gains may be nullified. We cannot give up with the kite record attempt not only because of our will to succeed but also as a gesture of support for the struggle that the Viants go through on a daily basis.
Doug la Rock's great hydraulic tension gauge provided better than anticipated line tension readings. The needle is steady and the mechanics very robust and durable. We joked that it made my winch looked amateurish. The surprise was the 30 lb tension in moderate winds and the 120 lb maximum tension in very strong winds. I expected at least 200 lb tension as a maximum and normal tension in the range 50 - 100 lbs.
The winch was refined over 7 years but some niggling problems persist that require a more permanent and robust solution. 12,000 meters of line is now the standard length on the storage reel. Here is white 450 lb Dyneema from French company, Cousin-Trestec. The line was supposed to be 250 lb but was mislabelled. It looks thin enough in the image but is actually 40% thicker than 250 lb line, a major factor in not echieving record altitude on day 4. Two other reels are available, each with 12,000 meters of line
The computer screen constantly displays the kite's position and altitude from data transmitted at 0.1 sec intervals.
This image taken below the line as it leaves the winch makes the line look like it is fat and snaking. High frequency vibrations produce this effect as well as a high pitched scream.
Preparing he kite for launch on day one. This kite has made over 30 flights since 2007. Unfortunately it was destroyed by a storm a few days later, flying in 50 knot winds.
The woolshed has been our home for the last few attempts since our camp was washed out in 2009. It's drafty but very durable and offers a degree of comfort but would be rated as one star :).
Compare the above wind profile (green line) and you can see there is a big difference between 29/09 kite shredding winds and 30/09 winds that would see the kite struggle to pass 6,000 ft.
1. New line 180 - 200 lb ultra-thin Dyneema 30,000 metres.
2. All line fault tested with capstan to capstan brake system.
3. Larger disk brakes on capstan to control rapid line release.
4. Brake on reel to eliminate overrun on rapid line release.
5. Larger 1.1 kw TECO motor.
6. Stronger capstan shaft mounting to eliminate runout.
7. Better line guide to improve line behaviour on capstan.
8. Use only upgraded reels to eliminate vibration and runout.
9. Use 0.75 kw motor as backup.
10. Improve motor control switches.
11. New laptop.
12. Laptop screen surround to improve screen visibility.
13. Better prepared accommodation and supplies for a longer stay.
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