Have a look at this video, which hopefully explains it a little better.

The problem with going fast is that you need to be able to support and transfer very large forces into the ice, and to do this the machine needs to be strong, and relatively stiff. When you need to absorb bumps over a range of speeds, this presents huge problems for a structure carrying high loads and a sophisticated suspension system is required. However, active controls are not allowed and there are also issues with the size and frequency of the bumps. The skate weighs over 50 kg and it needs to move at at a speed of up to 50 Hz over maybe 2-3 inches. To save confusing everybody, I won’t go on , but this challenge is nothing short of impossible. Imagine driving your car with steel wheels and no tyres over concrete speed bumps at irregular intervals at 120 mph.

Walking over the surface at slow speeds, you really don’t get a proper picture for the size and frequency of the ice bumps and I had been way too optimistic of what the natural flex of the main beam would accommodate. The end result is that the craft suffered a couple of failures during the first sail, that I was unaware of at the time.

Firstly the main sail bearing for the top section failed. This was a huge surprise and has performed perfectly for thousands of miles on land. It is a big industrial, self aligning machine bearing, that is rated for over 300 kg of axial load. The sail only weighs 25 kg, so well within design range. Secondly, the counter weight on the top section had bent very slightly down, meaning I could not extract it from the composite sleeve in the wing. This tube supports a lead weight in the end and was designed for dynamic forces of 10G (ten times gravity) to cope with any accelerations. However, it yielded.

Both these failures point to vertical accelerations of over 10G at the top of the mast, which is completely unacceptable. It felt rough from the cockpit, but not that rough!

Adding to the problems the lake had some more snow over the last day or two, which have exaggerated the drifts, extending the time that it will be out of action.

For now we have packed the craft up and will be repairing the two problems (easy fixes), but I am uncertain when we will be able to run again.

The bottom line is that to go really fast, the surface needs to be flat and this only happens at the start of the season, after first freeze and before any snow, or at the end of the season in March, when the surface melts, before the ice breaks up. My gut feeling is that the only opportunity is going to be after first freeze in December, but we will see. If the ice does get better this season, we will be back, but if not, then I guess I will be sitting by the lake in December while it is still water, waiting for the freeze.

If it was easy, everyone would do it, right?

The Greenbird ice craft is now set up at Canyon Ferry. The ice is in reasonable shape with a usable area of about 2 miles by 0.5 miles. This is tiny compared to the whole lake, but also huge compared to the runways we use to run on in the UK, so it should be enough room. We have one little modification to do on the steering system before we are able to run at any speed, but this is under way and will be finished in a day or two.

One thing that is already very clear is that the weather at the lake is almost completely unpredictable. It seems to have its own micro climate that differs from surrounding towns and the forecast! (wind can funnel down valleys differently, giving very different patterns on different sides of hills) The only solution will be to stay on permanent standby, near the craft. The week ahead looks quiet and warm (great to improve the rough ice surface) then a new weather system should move in towards the end of the week. As long as there is not more snow, we should be in very good shape by the weekend.

(Technical note: even a light dusting of snow can make the lake unusable. The moment it snows, it is not necessarily a problem as it is still light and fluffy, but it quickly drifts with the wind into sizable mounds, which then freeze into solid lumps, turning the smooth ice into more of a mogul field. To be able to approach record speeds, we need snow free ice for a minimum of 3 miles)

However, conditions have improved much sooner than we thought and after local inspection on New Years day, a significant part of the lake was clear and usable, with ice conditions improving all the time.

I therefore jumped on a plane and am currently on route to San Francisco, where the team van awaits. After a 1000 mile drive to the frozen north of Montana, we will set up on the lake, hopefully next weekend.

Many thanks to Dave, John, Jim, Dale and all the locals for the detailed weather reports over the past few weeks, much appreciated.

Time to make the sacrifices to the weather gods and hope the snow holds off for as long as possible!