ArthurSmith

All I meant was if your model is an accurate predictor of reality (Kepler's ellipses) keep the model. If not, discard the model rather than reality.

Experimental evidence beats intuition.

I can see there is a difficulty. I'll wish you well and take my leave.

I mean Uri Geller got his come-uppance.

That's a shame. If the claim (the possibility to exceed windspeed when travelling directly downwind powered only by the wind) is crackpot and/or its chief proponent is a crackpot, wouldn't it be better to address and expose the claim scientifically rather than hide it?

As I said, I'm new to this site. The accident that brought me here coincided with a short period of "enforced" bed rest with a respiratory infection that is rapidly subsiding but gave me ample opportunity to indulge my internet addiction. In looking back through old threads on this site, I see it has been going for twenty years and was the brainchild of one Tormod from Oslo. So congratulations, Science Forums on reaching the double-decade!

Unfortunately, I agree. By the time it it is obvious to all that the changes are happening now and chaotic, not cyclical, it will be too late. It is, in my view, already too late but I sincerely hope I'm wrong. And I sincerely hope you are right. Just in case, I've chosen to live at an elevation of 280m. Coastal dwellers, pacific island nations, New Yorkers may need other plans. Well, again, lets hope you are right. The problem is life is an experiment without a null hypothesis, there is no way to revers the time variable. The annoying thing for me is that so many things we can do to reduce carbon emissions, pollution, habitat destruction and so on would be worth doing anyway if Climate Change were a myth.

Or we could cut to the chase and consider the downwind case. I hope nobody disputes it is physically impossible to sail precisely upwind using fixed leverage of the wind against any other medium: water, ice, solid ground. And of course there's no question a turbine arrangement would not work, contrary to the direct upwind example (storage on board such as batteries is ruled out). So is there a way to operate a wind-powered vehicle directly downwind and achieve sustained speed in excess of the wind?

Regarding the limits of fixed sail. I've seen video of recent America's Cup racing where the yachts are up on hydrofoils. According to impressive graphic overlay, they are approaching 4x true wind speed at times. Ice yachts have gone beyond 8x true wind speed. There's a land yacht, Greenbird, that holds the world record for speed Vs ground that achieves similar leverage. I could dig up links if of interest.

Sure one can criticize the details. Excess deaths is broad-brush but it solidly confirms a steep rise in death rate coincident with this pandemic. Data is gathering daily, treatments are developing daily and virus is evolving daily. We'll see what happens.

That's the snag with real life. There's no control to the experiment. Climate change is happening and I doubt there's enough time for humanity to affect the change. I'd love to be wrong for the sake of future generations.

Happened to me once. Was invited to do a guest post on a pro-intelligent-design site. The opening post was technically by the guy inviting me and I participated in the comment thread. Lively discussion ensued, over a thousand comments over a couple of days, then I find I can no longer log in and all my comments disappeared. The site owner had decided to end my participation for good. The OP is still there along with the surreal comment thread. That site has not thrived since. But then neither has "Intelligent Design".

That's unfortunate, though not unprecedented. Even it was at his own request it's a bit like erasing history.

No problem. It's just a teaser. One solution is to mount a turbine on the vehicle and drive the wheels with it. Practical tests have achieved twice windspeed upwind.

Well maybe we agree. The limit to using wind power is how much wind you can interact with and how efficiently you can harvest it. Is there an avenue to harvesting and storing energy and storing it, then using it as needed? Of course, yes, in the general case. That's why Elon Musk is focused on battery technology. But can you redirect the wind to sidestep the limits of fixed sails? Can you sail directly upwind using the power of the wind if you adapt a sail?