Kites

[rob denney]

Chris,

Fubn thread. Kites, pumping, now windmills.

Is the windmill thread still going? I built a 9.5m dia windmill driving a 1m diameter propellor on a 9m cat a few years ago. Went directly into 20 knots of breeze at 6 knots, despite a bunch of inefficiencies.

regards,

rob

[CT 249]

Interesting beast, Rob. There was a windmill rig on a converted Daimond in NZ years back too, wasn't there?

[daveculp]

Originally Posted by water addict

You literally have a flapping wing with practically no energy input- here again the trick is to pop at the resonance frequency of the rig.

This is really interesting stuff; thanks. Your point about using resonant frequency vibrations is an excellent one.

Dave

[daveculp]

Originally Posted by rob denney

Is the windmill thread still going? I built a 9.5m dia windmill driving a 1m diameter propellor on a 9m cat a few years ago. Went directly into 20 knots of breeze at 6 knots, despite a bunch of inefficiencies.

At the risk of drawing the trolls back out; it's interesting to note that the scenario of a windmill boat sailing dead to windward, at any speed greater than zero, is precisely analogous to that same boat sailing dead downwind, at some speed in excess of the true wind speed--only the relative fluids are reversed. That this is so tough to demonstrate has to do with Rob's inefficiencies, not the mathematics of it. (has to do with gaining buoyancy and hull drag from within the high-speed versus low speed fluid--works in your favor when windmilling upwind; works against you when water-milling downwind; when you use a water-supported hull for both)

[rob denney]

G'day,

Jim Bates built Te Waka, a Diamond cut in half lengthwise and reassembled with a large triangular piece inserted in the stern. The windmill was similar to mine but smaller (other way round, he was first), but he claimed better performance, 7 knots up, down and across the wind, from memory. He was an engineer, with associated skills, money and equipment, so this is believable.

Neil Bose put a 2 blader on a 19' heavy mono in Scotland. Very nicely done, helicopter blade controls and commercial controllable pitch prop. Worked as well as could be expected.

Jim Wilkinson put one on a 26' Scirrocco cat, cruised across the english channel and back (mostly under motor, as no wind). He has since built a bigger one, taking my biggest in the world record.

Phil Weld was involved in a day sailor version in the USA, built by Havilah Hawkins. Featured in Wooden Boat, I think.

Fun times, sceptics were even more vociferous than they are now about proas and kites!! And just as wrong.

regards,

rob

[cristofa]

A note for those interested ... Dom Mee has set out on his attempt to cross the Atlantic in a (very tiny) kite powered boat, and you can check out his progress at

http://www.dommee.co.uk/pgs/news/kit...news-LIVE.html

While I wasn't too happy about his claim to have 'the first ocean-going kite powered boat', I have a fair idea what he's taken on and wish him the best of luck.

Christopher

[cristofa]

Further to the Dom Mee transatlantic kite powered boat saga ...

http://kitequest.typepad.com/mission...09/rescue.html

Christopher