Aptly named Sailrocket, blasts off!
17 November 2012
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.
Those of you that have been following this blog know that I’ve been giving Sailrocket the best chance of increasing the sailing speed record, as soon as they got their (earlier) control issues worked out. They’ve done that and it’s obvious! Early in this blog, I stated that stability was the key to high-speed sailing and Sailrocket has proven me out. It’s interesting that when you get a real certainty in an area, you start to wonder why it’s not obvious to others. But the truth is that it took some work on my part to gain that certainty, and not many others have had that opportunity. It takes some time to change people’s understanding of how things work, when a new idea comes along. Bernard Smith started that new idea with his book “The 40 Knot Sailboat”. Sailrocket has proven Smith right – but not just 40 knots, rather 60 knots and beyond!
What is the potential? I believe I stated that earlier and that it is simply a matter of fluid dynamics and structural engineering; fluid dynamics to design the most efficient craft possible (high-power at low-drag) and structural engineering to design the strongest, lightest craft possible. What speeds do I think are possible? I can’t say because I haven’t attempted to compute them. All along, the one thing I have known is that any speed that any sailing craft was able to achieve using weight for stability, (including Innovation, Hydroptere, kite-boarders, and windsurfers, etc.) could be easily beaten by a craft that was dynamically stable, this stability achieved by properly aligning the forces that drive the boat. Sailrocket, as conceived and executed by Paul Larsen, Malcolm Barnsley, and the whole VSR team, has demonstrated this to the Sailing world.
My own certainty of what the potential was came about in 1985 with my first successful model of what Bernard Smith called an “aero-hydrofoil”. A photo of that model is at the top of this blog page. I believe that a better term than aero-hydrofoil is a “force-aligned” craft, a term I’ve heard others use to describe this type of craft.
An interesting problem I encountered early on was that some sailors thought that “an inclined airfoil is inherently unstable”. I already knew from my own experience that that statement was false. I suspect that the flip of “Delta” (follow link “Sailien prototypes (early), Delta, etc” in the sidebar) may have started that false idea. Delta was derived from Smith’s “Monomaran”, a design that violated the concept of a force-aligned craft by putting the leeway resisting (and steering) foils on the lee side of the craft, under the corners of the airfoil. This is a guarantee of a flip -- if the craft ever gets powered up. While my craft looked quite similar in many respects, in function it was essentially the opposite; my steering and leeway resistance was positioned on the windward side of the craft and there was no leeway resistance elsewhere. This is the most important arrangement for a force-aligned craft that does not use down force for roll stability. Note that Trifoiler is a force-aligned craft, but it uses down force from the windward foil to achieve stability.
What’s next? While Sailrocket is a real sailing “rocket”, it is not a practical sailing craft. The next step to getting stable, high-speed sailboats available is to develop practical craft that will sail all points of sailing that a normal sailboat can sail. I actually did that with the 1985 model and with all the later full-sized prototypes. The only real problem has been low wind-speed performance, but this can be worked out without too much difficulty. Anyone interested in working on this contact me.