High-Speed Sailing

Vessel Name: Sailien
Vessel Make/Model: Experimental/custom
Recent Blog Posts
28 September 2013

The America’s Cup

I watched, with interest, the videos of the 34th America’s Cup. At last we have fast sailboats engaged in a competition that is fun to watch. The virtual images (such as course boundaries, distance grid lines, separation between boats, etc.) overlaid on the real images really helps to keep the race [...]

31 August 2013

100 Knots for Hydroptere?

The latest news from Hydroptere is that they have plans for a 100 knot sailboat. This was posted on 26 Aug 2013, so look for that date at this address. http://hydroptere.com/en/the-news/last-news/

17 November 2012

Aptly named Sailrocket, blasts off!

While yet to be ratified, Sailrocket posted an average speed over 500 meters of 59 knots. I will not be surprised if they increase their record into the 60 knot range during this record attempt.

02 January 2012

More drag for VSR2?

I want to start by pointing out that the whole VSR2 team has done a stellar job and has demonstrated conclusively that the forces that drive a sailboat can be aligned for roll stability without using ballast and without using any down-force. (Trifoiler achieved roll stability by using down-force, but [...]

18 December 2011

My analysis of Sailrocket

I copied a diagram of VSR2 (wing doesn’t show well) and added in the major force arrows that apply. Be aware that these arrows are not correct in terms of scale (length) and some of their locations are guesses, however I believe I’m correct enough for us to learn something about what VSR2 has been [...]

23 October 2011

60 is within reach, what’s next?

I have been watching Sailrocket’s progress with great interest and there’s no question they have a winner. I fully expect to see them reach 60kt in the near future. Sailrocket has now demonstrated what I first learned with my models and again with my full-sized prototypes, that if you get the forces [...]

Outrunning the wind that powers you!

03 April 2011
A friend tipped me off to an interesting project that I’d like to comment on. Some of you may have seen the land vehicle that went straight down wind reaching a speed of 2.8 times the true wind speed. (The true wind was powering it.) I recommend that you read the article about it at this address: http://www.wired.com/autopia/2010/08/ddwfttw/all/1

Yes it tends to “wrap your brain around a lamppost” trying to understand how you can go faster than the force that’s pushing you! Interestingly enough, I’ve already explained the elements of how this can be done earlier on this blog, but I hadn’t considered how it could be used to go straight downwind till now. Please refer to my earlier posts: “Faster than the wind.” 5 May 08, “More on sailing faster than the wind.” 6 Sep 08, “From soap bars to land yachts.” 7 Sep 08, “How fast can we go??” 9 Sep 08, “The speed limit.” 14 Sep 08, “Squeezing our craft on ice or land.” 20 Sep 08, and “The water’s squeeze” 21 Sep 08.

After reading my earlier posts, watch this video: http://www.youtube.com/user/axelerat3d#p/a/u/2/UGRFb8yNtBo

That video gives a good demo of what I described in my earlier posts about the balloons interacting with the airfoil. However what they omitted is how the sail or propeller is powered. All that’s missing is the rest of the balloons (air particles) and it now becomes obvious that the transfer of energy from the “balloons” to the sail/airfoil/propeller is what provides the power.

What may not be obvious yet is: if the airfoil is on a platform that is moving away from the wind at a speed of 2.8 times the wind, wouldn’t the energy transfer slow the craft? Here’s the tricky part and this is not clearly shown nor explained; the speed of the propeller’s rotation and it’s angle of attack, causes each “balloon” to push the propeller blade forward a bit as the propeller swings past it, and “climb forward” to the next “balloon” which also gives a tiny push and so forth. This is in exact accordance with my soap bar analogy and how a slower motion can generate a faster motion (the soap bar squirt!) In essence what we have is the propeller is continuously “tacking” downwind (shown in the video demo), whereas a sailboat has to tack the whole craft to do the same thing.

Rick Cavallaro and John Borton did an outstanding job in creating the “DDWFTTW” “Blackbird”. Note that “our own” Richard Jenkins (Greenbird) shot the video of Blackbird in action.

Bob
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