Blackbird faster than the wind

And this is news?

Led by Rick Cavallaro, DDWFTTW has developed a wind-powered car called the Blackbird that is capable of traveling upwind at speeds faster than the wind! In 2010 Cavallaro’s team set a world record by traveling downwind at 2.8 times the speed of the wind – and they recently tweaked the vehicle to travel upwind as well. The downwind record was an amazing accomplishment, but the latest feat is even more astonishing.

Astonishing?  Sailboats do it regularly, creating apparent wind – hell, even my cat did that.  They’d have been better off with a sail:

[H/T haiku]

17 Responses to “Blackbird faster than the wind”

  1. Sniper July 13, 2012 at 15:02 Permalink

    Known, probably, to that Italian bloke.

    http://www.youtube.com/watch?v=iygLgI25WOg

  2. Mark in Mayenne July 13, 2012 at 17:14 Permalink

    The special aspects of these feats were that the directions of travel were directly downwind, and directly into wind, respectively.

    It’s well-known that sails can move boats or land vehicles at speeds faster than the prevailing wind, but it was believed to be impossible to create a wind-powered vehicle that would go faster than the wind directly downwind, or that would “sail” directly upwind.

  3. James Higham July 13, 2012 at 21:19 Permalink

    No one sails directly upwind, Mark. They tack or go as close to 45 degrees to the wind as possible. The modern Bermudan can pinch to about 37/38 degrees, the older craft to about 50 degrees. Those land yachts could pinch into the wind but essentially had to tack most of the time.

  4. Mark in Mayenne July 13, 2012 at 21:42 Permalink

    Agreed, but this new machine uses wind power to move directly upwind (from a standing start). That is, at 0 degrees to the oncoming wind. That’s what the fuss is about.

    The fuss is also about the fact that it went directly downwind faster than the wind, from a standing start, which is also impossible with a conventional sail.

    The wind drives the propeller that drives wheels and the whole thing goes upwind (or downwind faster than the wind)

    (I windsurf; whilst not being an authority, I know a bit about sails. The fact that it’s a propeller is why I put “sail” in inverted commas, although they are both aerofoils)

  5. James Higham July 13, 2012 at 22:05 Permalink

    Point taken about conventional. A slotted wing though, such as this:

    http://archive-other-nour-obscur.blogspot.co.uk/2012/07/c-class-downwind.html

    … will generate higher than flat index by a considerable amount and by the apparent wind generated, admittedly cheating in that the sail is not directly facing the wind flat, the boat goes directly DW.

    Upwind, the angle of attack is much broader than the soft sail and so it can sail virtually upwind.

    However, point taken about the propeller and cogs.

  6. Rick Cavallaro July 14, 2012 at 04:10 Permalink

    Mark is correct in saying that our vehicle is designed to go directly upwind and directly downwind. No traditional sailing craft can go directly upwind, nor can it go downwind faster than the wind – no matter how much you flatten, camber, or slot the sail.

    I will point out however that when configured for downwind operation we use a propeller that is turned by the wheels, but when configured for upwind operation we replace that propeller with a turbine, and it then turns the wheels (rather than the other way around).

  7. Rick Cavallaro July 14, 2012 at 04:11 Permalink

    > And this is news?

    You posted it on your blog :)

  8. James Higham July 14, 2012 at 06:52 Permalink

    Thanks Rick for those. Consider my wrist slapped and humble pie eaten. I’ll follow your story with interest, bringing developments to readers’ [mainly UK and U.S.] attention and see how the commercial application comes along.

    I’d be interested in how you settle on your blade section. Not exactly an NACA section it seems – more like an Eppler or Speer. Maybe that’s a trade secret.

    http://www.fasterthanthewind.org/search?q=blade

  9. Mark in Mayenne July 14, 2012 at 07:13 Permalink

    I will watch here for the news. Thanks.

  10. Rick Cavallaro July 14, 2012 at 07:47 Permalink

    There’s been no wrist slapping nor humble pie served. You’ve been downright kind compared to the treatment I’ve gotten from many skeptics.

    Regarding commercial applications – there are potential applications, but I haven’t planned to pursue them. I’m enjoying my day job pretty well.

    The blade section for both the prop and turbine is the NACA-6412. I made it somewhat thicker at the root to accommodate the carbon windsurfing mast spar.

  11. James Higham July 14, 2012 at 09:22 Permalink

    So, a modified NACA – you couldn’t go wrong with testing.

    http://www.engr.sjsu.edu/nikos/MSAE/pdf/Shethal.F10.pdf
    http://www.eng.buffalo.edu/~kclefort/PDFs/Aero_Project.pdf

    Have you looked at Tom Speer, although he is more on hydrofoils and sailing foils?

    http://www.tspeer.com/

    I’m not saying you need to because you’ve obviously done your R&D but he was most helpful with tunnel testing for hydrofoils in a design I had. I liked his 105, which had sweet exit characteristics.

    Sounds exciting, the whole project.

  12. Rick Cavallaro July 14, 2012 at 10:37 Permalink

    “you couldn’t go wrong with testing.
    http://www.engr.sjsu.edu/nikos/MSAE/pdf/Shethal.F10.pdf

    Shethal theoretically wrote that report as a part of this project. The story is too tragic to go into here.

    “Have you looked at Tom Speer…”

    Tom was with us on that fateful 104 deg day at New Jerusalem – 3rd duck from the left:

    http://upwindfasterthanthewind.shutterfly.com/pictures/9#15

    But if he had a better airfoil section for us, he was holding out :)

  13. James Higham July 14, 2012 at 12:01 Permalink

    That’s fair – might be best if I keep my thoughts to myself. LOL. It gets more and more interesting, Rick. You have the immortals on your side, it seems. Shall watch with great interest, as I’m sure will Mark. OK, I’m here to learn.

  14. Rick Cavallaro July 14, 2012 at 13:55 Permalink

    “might be best if I keep my thoughts to myself.”

    That would be no fun at all. I originally conceived this as a brain-teaser, and posted it on a kitesurfing forum to spark discussions like this. I soon learned that I wasn’t the first to conceive of such a vehicle – but there didn’t appear to be any reasonable real-world proof that it would do as my simple analysis claimed.

    The amount of skepticism was astonishing. There was no shortage of experts, including aero and physics PhD’s and professors, assuring me it was impossible. Plenty of skeptics (or more properly – deniers) insulting and attacking me.

    The even more surprising thing is that some deniers remain – including some relatively high profile physics professors. I’ve built a number of small working models and demonstrated them in the controlled environment of a treadmill, posted detailed build videos so others could build their own and reproduce my results (and several have), posted analyses, and then went on to build and document a manned version that set world records upwind and downwind in front of qualified and critical 3rd party observers.

    Obviously, this internet pissing match got way out of hand, but as you say, it’s been an interesting project.

  15. James Higham July 14, 2012 at 15:26 Permalink

    The amount of skepticism was astonishing. There was no shortage of experts, including aero and physics PhD’s and professors, assuring me it was impossible.

    Yes and looking back at my post, it looks like that from me but I’m more usually supportive than not and once I saw what it was about, I swung in behind. It clearly works, Rick.

    This gets up my nose when something clearly “is” and yet others flatly refuse to accept it.

  16. Mark in Mayenne July 14, 2012 at 20:23 Permalink

    I know that feeling :)

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