After looking at the GPS, I am really not to worried about the crafts performance, and will be bringing you data on this shortly. The real problem is the ice surface.
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?