Sailrocket 2 set to launch

Sailrocket

5 attempts today-and no luck. I was going to say:"Don't cut the foil-add to it!" but I'm too late......
http://www.sailrocket.com/blogs

Good luck tomorrow!

 

Chop it all the way off!!! Come on you speed freaks go for it! You know you want to ! And maybe get that old trapeze handy....

 

The results showed what seems to be no detectable change after first 15 cm and then 30 cm total length reduction.

The lack of change is the most puzzling thing at this point.

I would have expected a speed reduction with area reduction until cavitation mode takes hold.

 

Sailrocket

The more I thought about it the more it seemed like the way to get the thing to start working was to increase the area-which would have had a similar effect to carrying more weight since the foil pulls down. When weight is added it reduces foil loading! But cutting the foil down increases the foil loading. I don't understand enough about the supercavitating foil ,I guess....

 

Sailrocket

51.33 today........

 

Sailrocket

Poor runs today and the sub-cavitating foil destroyed. Today was not the best way to end an attempt that has come so very close....

 

The first official round with the new boat did not pan out with big numbers, but all is not lost.

They worked through a few handling issues and proved that they could reliably go out in stronger winds that ever before.

The basic boat, cross beam, front steer rudder and wing assemblies are now "tried an true" tools. No real need for much work in any these areas.

As expected, the big unknown was (and continues to be) the foil. They went at it with a good plan, but it was not to be. At least they can take what they learned, and focus on trying some new stuff.

The track record for this team says they are not done yet. They also seem to be willing to incorporate "outside of the box" thinking that put them in great position for a leap in performance if they can crack that one last nut (the main foil). I greatly admire this whole effort and fully expect them to succeed.

 

I'd suggest to the kite/wind surfer crowd to come up with a stepped hull cat/tri configuration for more power-less drag and skip the foils.

 

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What would you say to the Hydroptere crowd that still holds the mile record and whose peak speed exceeds Sailrocket and the Rob Douglas record to date?
( sorry, couldn't help myself! )

 

Damn good job but I still think foils will have a lower high speed limit than other ideas. Where they shine are high speed rough water challenges. Hydroptere is more of a "boat" usable on seas and all courses. Record machines tend to be single purpose whether on land or sea which narrows the challenges they are qualified for. I think you'd agree these are apple/oranges comparison. Finding the fastest fruit basket does tend to upset the apple cart of convention. Certainly the development in foils is being helped by these exciting efforts but a willingness to be "unattached" to a approach may be the supercavitation that is required to break through the barriers. Certainly sailrocket has shown a reliable consistant ability to hit 50 knots which is nothing to be ignored.

 

I would tend to attribute the max peak speed success of the Hydroptere to the amount of foil research that went into the design with a significant contribution from scale (bigger really is better for a large number of parameters).

The big French Foiler has struggled when they took it out in rougher seas. It can handle "chop" but it was not designed to ensure it can stay up on the surface piercing foils when the boat needs to be "following" a surface up and down.

For very high speed open water efforts, lifting foils combined with long efficient hulls (Banque Populaire V) seems to work well in the rough given that when the foils and hulls just naturally work together to keep the ride smoother than either can do alone. The smoother ride translates into both less drag and less structural stress due to pounding.

I am sure that a design that uses foils to lift the boat such that the hulls are clear of the water in the rough is possible, but it would probably require constant active elevation / attitude control. Theoretically this can be manual (pilot), self powered (wands / feelers / floats) or "fly by wire" with electronic controls and powered control surfaces. As long as the latter used wind power (small wind turbine) to generate the power, a few would fuss but most would concede that intent of "wind power alone" has not been trampled. The cost to develop such a system at the required scale will be high.

If they get it right, the payoff will be the ability to go 25% - 50% faster in the rough when you have more than enough wind, but are currently limited by structural concerns with the pounding that any displacement mode boat will see.

If someone does figure out all of the above, the non-cavitating profile foils would probably still be the right choice initially. Eventually, such an effort may find themselves up against the same kind of foil performance wall that Sailrocket and others have hit. Use of supercavitating concepts at that scale are conceivable, but I just do not see it until the entire state of the art for high speed open water sailing has advanced a bunch from where we are.

 

Sailrocket

From Scuttlebutt tonight:

* (December 16, 2011) - The World Sailing Speed Record Council announced
the ratification of a new B Division (from 150 sq.ft up to and inc. 235
sq.ft) World Record. Paul Larsen (AUS) sailed Vestas Sailrocket 2 to a
speed of 49.19 knots on a 500 meter course at Walvis Bay, Namibia on
November 30, 2011. Larsen was the previous recorder in 2008 on Sailrocket
1, setting a speed of 47.36 Knots on Walvis Bay. --http://tinyurl.com/WSSR-121811

 

I'd say that 5 kitersailors smashed your 51.36 knot run and 3 kiters set new faster outright records. Kitersailors and Sailrocket continue the quest for 60 knots while Hydroptere has retired from outright record attempts in order to pursue slower speed sailing records.

 

In a phony, cheating, trench/ditch they did - let's see them in open water, like everyone else.

 

Gary: I question the use of the word phoney, it did indeed happen and required great skill and a lot of preparation.

However, I would agree that, due to the entirely different and rather artificial conditions, ditch surfing belongs in an entirely different category and comparisons with it do not belong in this thread. If it comes to that, Sail Rocket, sailed one way parallel to a beach that happens to have the right combination of wind, wave and bottom in carefully chosen seasons, while another great adventure, scarcely bears comparison with those like l'Équipe Hydroptere who strive for open water records in a vessel actually capable of going from one place to another in whatever conditions prevail at the time.

Different strokes for different boats and folks, it's a big world, plenty of room for everyone without getting upset about others trying to excel by a different route. It's strange though, how close the best speeds of these three entirely different classes of vessel are.