June 2006

Newsletter, June '06

It's not a recent discovery, nor even original I wouldn't think (not wanting to give credit where it possibly isn't deserved), but Australians have found two new uses for sheep:- meat and wool.

But here's something that is new from Aus.- or by Aussies at least- a new use for a kite- a Venom 19 no less.

But I'm getting ahead of myself.

In (October?) 2004, Aussie Ben Deacon arrived on our doorstep fresh from having kite skied across Greenland.

A glutton for punishment, he'd decided to do it again-  but sitting down (feeling his age maybe?).

Anyway, he wanted us to build him a ski buggy- and just wouldn't take no for an answer when we explained the various reasons why conventional ski buggies probably wouldn't be up to the job- as was shown by the well funded but completely unsuccessful attempt at a trans-Antarctic in '02,  photo. attached.

The problem is steering; skiers get directional control by using a combination of weight transfer and ankle movements to make their ski's tilt onto one edge and bend to the desired radius.  When ski's are attached to a chassis of some sort, the complex interactions that this requires are not available.

The usual steering system for ski equipped vehicles is therefore to use multiple short skis with one or two of them mounted on steerable pivots.  Snowmobiles are an example.

Unfortunately, this type of steering is not nearly as efficient as tilting and bending because the skis sweep out a wider track when turning than when running straight.  For snowmobiles, this extra drag can be countered by cracking open the throttle- but kite powered buggies don't have this option- or rather they can steer this way,  but will be left behind by more efficient kite skiers- which isn't a good look.

I'd had a solution to this problem in mind for years but had never actually made it happen- until Ben came along with a well timed kick.

This solution is to bend the ski's sideways- and to allow this, each ski is made of multiple longitudinal elements, able to slide lengthways relative to each other but dovetailed together to prevent their separating. The first KiteSled was built in just three days, and worked immediately.

A patent application was then filed.

Lack of useful testing conditions has been the main impediment to progress since then- NZ has snow in the winter but our winds are in summer.  Most of the initial testing was therefore done in Australia- and in an advantageous spin-off, the ABC  (Australian Broadcasting Corp.) consequently made a KiteSled segment for their popular Catalyst  program. 

We did send a prototype KiteSled for trialing in Canada during their 05/06 winter but this was less than satisfactory as users reported a tendency for the tail to slide out- which had not manifested here nor in Australia, nor later in the trans-Greenland (but I'm getting ahead of myself again).  Not being able to experience what was happening at first hand, for the next versions I reshaped and sharpened the ski's central steel rib, and added extra adjustment for longer legged users- on the assumption that the reported oversteering was caused by some combination of hard ice (rather than snow)- and sitting too far back. 

The next step, in preparation for their first trans-Antarctic was for Ben (and Patrick Spiers) to take two KiteSleds to Greenland.

In Ben's own words:

 Hi guys!!!
Just got back. Wow, what an incredible trip in the most severe arctic conditions. COLD!!!!!!!!! and windy, and windless.
The big news is the sled is a real success. We got it right. You all did the most amazing job in design and construction. The level of workmanship was so high, not a bolt came undone nor anything broke. 
The real story of this trip was that the weather was far more extreme than we could have imagined. We were there a month earlier than my last trip, and we ran into a pattern of very violent storms followed by clear, cold calms with temperatures down to -40C. The result was we only got a fraction of the usable wind I got on my last trip. The pattern was often that the wind would pick up, we'd head off, then after a few hours we'd be enveloped in a white-out, with winds blowing over 30 knots. We'd put the kites down, fight to put the tent up (without it blowing away) then sit out the storm. We'd wake up the next morning to lighter winds, head off again, before the winds died a few hours later. There'd be a few days calm, then the cycle would repeat its self.

On one of the first nights, the temperature plunged, -30 odd. the sleeping bags we had- good enough for Everest,  were nowhere near warm enough, and we shivered horribly all night. We knew it was going to get colder higher up, and we thought we might have to abort the trip. Then, V-19's to the rescue: Folded three ways as a bed-spread they increased the warmth of the bag by 20 or so degrees. In -40 our noses would sting  from the cold where they poked out of the sleeping bag, but we were warm enough. They saved us!   Needless to say, in conditions like this we weren't able to make the 1000km+ distances we'd hoped for. In the end we did a bit over 700km. 
What we did get though, is the chance to test our gear and ourselves in the toughest polar conditions, and crucially in the whole range of conditions you actually get, rather than you hope to get. We found, as hoped that the sled is quite a bit faster than skis. Skis would become unstable at about 30-35 km/hour, where the sleds were quite happy at 40km/hour, loaded up with 100kg+. I reckon the sleds have a 20% speed advantage over skis, which is a hell of a lot. The seats were super- comfortable, and the ergonomics really good.
The surprising thing was how the sleds performed when there wasn't any wind. We could have chosen not to haul the sleds at all, but there were so many windless days we had no choice. We learned this a critical part of the sled's design- they need to be as efficient to drag as to sail. Here we got very close, but can still do some work to optimise the performance. So in short, we imagined we'd go to Greenland, get ideal conditions, and break records. instead we got the toughest weather that place can throw at you, and came away knowing we'd built a superior technology that can handle one of the toughest places on earth. Pat, Andrew and I are pretty psyched now for Antarctica. Our design is good, really good. I reckon the PL KiteSled will become the standard design for this sort of thing

Ben Deacon

Fantastic Ben (and Pat).

And - did you catch the new use for kites!- bye bye baa baa's!

Peter Lynn

Ashburton,

June 1 '06.