Unless you can get the blades to reduce power I don't think playing with the alternator is going to cure things.
I had wondered earlier if Russell was on the top of a hill with a wind coming up at the machine, I was reminded of this problem when someone else reminded me that Bergey claim their machines won't handle this condition.
I am still not sure if this was the problem if the machine pulled back into the wind but it is worth investigating. If it was at right angles to the wind and the wind came from below then it could be the case. If it went back into the wind then it would run away from that condition alone and not need the wind coming up at it.
Not much point in worrying about the tail, I still think the offset is too small for this condition and if it is it won't turn down wind. These are extreme conditions, I have never had to experience such winds and what has always worked for me may have failed here.
Now about changes to the alternator and would it help.
Winding with more turns and reducing the cut in speed probably won't, it will get it more towards stall and may hold the condition off to a higher wind speed but it will fry easier when it gets out of stall.
Winding with thicker wire with less turns is a better way to go, it will increase the current capacity and increase the efficiency so you will get more power with less heating and this is very desirable under normal conditions. If under those rogue conditions the power available was within the rating of the improved alternator then it would have been ok. If it had pulled back fully into the wind then it still wouldn't have survived, there is far too much power available. Possibly with the lower resistance there would have been more chance of braking it but any brake switch would need to be at the tower with very low lead resistance, it may have given Russell more time to reach it in this case but no use if no one was there at the time of the event.
The fact that the blades survived makes me suspect that it was not developing the full power of an 80 mph wind so it may have been near the point where a bigger alternator could have coped but by reducing turns you will increase prop speed and that worries me, a burnt alternator is costly but not a disaster situation, shed blades would be a different matter.
I think Bob Golding has a point, reduce blade size but keep the alternator as powerful as possible and use the same offset so that it is bigger than normal for the blade size. Changes to blade profile could well solve the whole thing but there is no real evidence to base any new blade design on and it would be a complete gamble.
My immediate thoughts are to reduce the blade size, wind the alternator with more strands in hand with less turns ( the smaller prop will need more speed anyway), use a boost converter if you really want to keep the very low wind performance but otherwise make the cut in at 10 mph and you won't loose much in that wind area.
In the end the offset has to be sufficient to stop it holding up wind under any condition or it may still be worth trying the right angled vane with less offset..
It may be worth moving it from the very top of the hill to avoid the vertical wind components and perhaps try one of the smaller, tougher and better natured machines in that position.
There are a lot of other ideas that may work, the only sure cure is pitch control if you can build it reliably but you can play with tip flaps , servo yaw and other ideas but there could be lots of issues to sort out.
Flux
