Looking forward to Friday...
Wed, 12 Oct 11 13:23
We have had a spell of light to moderate winds which are unsuitable for VESTAS Sailrocket 2.
Today we managed to get most of the data logging action working our way. It turns out that there were a three independent problems that all happened at the same time. That old chestnut!
So we definitely won't be sailing today and it looks like tomorrow is pretty flat as well. The front planing surface has now been bonded on so we could be taking two people sailing in the next outing... starting with Helena. This will be a hoot.
Friday and Saturday are good forecasts so let's just hope that they hold up.
For those of you 'technophiles' who crave some more detail info on the boat, I have written up a good description of the wing and how it works. You can find it in 'The Boat' section of the website under 'Wing-Sail' . I reckon there will be enough info in there to keep most of you happy. As usual, feel free to ask questions. I always read the comments and reply where appropriate. Next will be a description of how the ventilated/cavitating foil works... the only trouble is... we are still trying to understand that one ourselves. All we know is that it seems to be working. I'll also try and talk you through a 'drivers perspective' of how we get VSR2 from satndstill and up onto the boil for a complete run.
Cheers, Paul.
Wing Extension
Submitted by Tim on Thu, 10/13/2011 - 22:29.Fantastic, Paul. Great explanation of a unique approach to a terrific challenge. Reading your explanantion, I'm reminded of the design challenge considerations of a high performance glider wing that has to efficiently perform over speeds ranging from stall in the low 40s knots up to 150 knots high-speed cruise.
The wing extension makes sense to raise the outboard float, but are you not also concerned about the wing extension reaching a critical angle of attack from any number of causes that might require an instantaneous response: high speed lift generation, pitching up because of swells or other turbulence, etc. I'll be curious to hear how the mass-balance approach works on the wing lift flap...it sounds simpler than a surface sensing wand. I wonder whether the wand ultimately proves to be the fool-proof mechanism?
QUESTION: You mentioned that you find it more efficient to turn the boat into the wind during start up rather than sheeting in. Is this done to unstall the wing and get the airflow attached?
I look forward to your thoughts on the ventilated foil. This is a fascinating piece of business.
All the best -
Tim, Vermont
Passengers
Submitted by P.Flados on Thu, 10/13/2011 - 02:09.You know that with two person capacity, you could consider a charity auction for a ride in the worlds fastest sailboat (soon I hope). I would not be a candidate (the travel cost alone are not on hand), but still I can dream.
Wing
Submitted by Mike Ewart on Wed, 10/12/2011 - 15:56.Paul that is great I was wondering if there was any adjustment in the wing extension, and I was wondering what to call it as well, do not underestimate the surface effect, in my youth I did some work on WIG craft and it is awesome the power developed, the experts then were the Russians.Probably still are.
Do you have the wing controls semi balanced ? or are you controlling them in both directions?
Wing extension in ground effect...
Submitted by Paul on Wed, 10/12/2011 - 17:01.Hi Mike,
We originally started off with the wing much lower to the water to increase the ground effect. I had concerns over it hitting the water if things go wrong and we end up out in the rough water at the end of a nautical mile attempt. I may have gone a little too high but I would rather this option as we don't know what conditions we may ask this boat to sail in yet.
The wing is pretty well balanced aerodynamically but it still has to be positively sheeted in to the wind. I am only using a 2:1 mainsheet system on the wing although it is pretty hard work when the wing is stalled early in the start-up phase. The load in the wing can be adjusted by pre-setting the angle of the trailing edge trim flap on the middle wing. The more I ease it out, the lighter the load in the mainsheet becomes.
I only use the forward bridle to lock the wing off when towing the boat or holding it on the shore.
Cheer, Paul.