Sail Aerodynamics

   Hi everyone. Not sure if this is a good place to start. I have gotten back into dinghy racing after a long time. Partly out of pure interest (Background is aeronautical engineering)but partly to help me work out good sail settings I would like to read up on sail aerodynamics. Has anyone got a good source for sail aerodynamics and how it affects different sail types, materials etc etc Any comments debate etc etc?

ps I am sailing a laser but hope to go to another more technical class one day.

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Cameron Winton Send Private Message Find Member's Posts Groupie Joined: 08 Nov 11 Location: Prestwick Online Status: Offline Posts: 41	Post Options Post Reply Quote Cameron Winton Report Post Quote Reply Topic: Sail Aerodynamics Posted: 05 Feb 14 at 8:56pm
	Hi everyone. Not sure if this is a good place to start. I have gotten back into dinghy racing after a long time. Partly out of pure interest (Background is aeronautical engineering)but partly to help me work out good sail settings I would like to read up on sail aerodynamics. Has anyone got a good source for sail aerodynamics and how it affects different sail types, materials etc etc Any comments debate etc etc? ps I am sailing a laser but hope to go to another more technical class one day.

Guests Send Private Message Find Member's Posts Guest Group	Post Options Post Reply Quote Guests Quote Reply Posted: 05 Feb 14 at 9:23pm
	Books by Bethwaite, Marchaj and Gentry are a good place to start. There are obviously similarities to wings, but also important differences, not least the fact that boats are righting moment limited and IMHO it makes sense to resolve the force into thrust and heel components rather than lift and drag ones, but that rarely happens in the literature. There are also some good websites around and MIT has some course notes on line I think.

Reuben T Send Private Message Find Member's Posts Groupie Joined: 22 Mar 13 Location: Lyme Regis Online Status: Offline Posts: 74	Post Options Post Reply Quote Reuben T Report Post Quote Reply Posted: 05 Feb 14 at 10:40pm
	one of the good websites I have found on the subject http://www.wb-sails.fi/Portals/209338/news/index.html

Rupert Send Private Message Find Member's Posts Really should get out more Joined: 11 Aug 04 Location: Whitefriars sc Online Status: Offline Posts: 8956	Post Options Post Reply Quote Rupert Report Post Quote Reply Posted: 06 Feb 14 at 9:13am
	This is an excellent place to start, if you love the technical, theoretical side of sailing. The way sails work is an infinitely fascinating subject. The above books mentioned are really good, even if my brain can't cope with some of it. Sounds like you will. A slightly more practical book, but still with theory built in, is Jeremy Howard Williams Small Boat Sails, which can act as a bridge between the physics and the real world.
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Cameron Winton Send Private Message Find Member's Posts Groupie Joined: 08 Nov 11 Location: Prestwick Online Status: Offline Posts: 41	Post Options Post Reply Quote Cameron Winton Report Post Quote Reply Posted: 06 Feb 14 at 7:29pm
	Thanks everyone guess I have a shopping list for the dinghy show! Can understand that there can be differences with how wings work, interested on how downwind sailing can be made more effective eg relying less on the aero drag for thrust

Oatsandbeans Send Private Message Find Member's Posts Far too distracted from work Joined: 19 Sep 05 Location: United Kingdom Online Status: Offline Posts: 382	Post Options Post Reply Quote Oatsandbeans Report Post Quote Reply Posted: 06 Feb 14 at 10:02pm
	Aerodynamics sailing books All the ones mentioned so far are good, but I also think that Manfred Currey's book from the 1920's The Aerodynamics of Sails, is great because it was the first to look at sails and try to work out how they worked. Lots of stuff comparing them with bird wings which is surprisingly good. What astounds me when you read around about the subject is just how little has been done on the subject and how poor is the relationship between the theory and practice for fast sails is. As I say Currey is great, as is Marchaj and Bethwaite, but the one that really stands out is Eiffel ( yes he of the tower fame). He did the first work on the aerodynamics of flat cambered flat plates ( ~1910 ) in his own home made wind tunnel. It appears to me that the numbers that he came out with for ideal sections have not been improved on, 10-13% camber giving the best lift to drag for a sail to windward, it seems to me that lots of the later papers seem to regurgitate his graphs.

iGRF Send Private Message Find Member's Posts Visit Member's Homepage Really should get out more Joined: 07 Mar 11 Location: Hythe Online Status: Offline Posts: 6499	Post Options Post Reply Quote iGRF Report Post Quote Reply Posted: 07 Feb 14 at 9:27pm
	You can study and read, study and read, then the more you do it, the more you realise what a black art the whole thing about foils, aerodynamics, bernoulli, attack angles, boundary layer, tip vortices, is, and you begin to wonder if they really know for sure. But you finally get your head round it start applying the facts and the results of your own research, ideas, work out what's fast and what isn't, what works with sails, kites and the hole gamut. And you think you know. Then you come across some stupid old boat built in 1999, with a full batten rig and you discover it's ten per cent quicker sailing off wind with the flow reversed across the foil.... Edited by iGRF - 07 Feb 14 at 9:27pm
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Strangler Send Private Message Find Member's Posts Posting king Joined: 24 Mar 06 Location: United Kingdom Online Status: Offline Posts: 154	Post Options Post Reply Quote Strangler Report Post Quote Reply Posted: 08 Feb 14 at 12:18am
	Surprised my favourite has not been mentioned - Arvel Gentry. Eminently readable. Unfortunately his website seems to be defunct. http://archive.is/tB3K2 You may finds some of his articles on 3rd party websites, eg- http://www.bethandevans.com/pdf/how_sails_really_work.pdf Just as well I downloaded them all a few years ago. ...Ahh this page links seem to work- http://www.ftp.tognews.com/Publications/Arvel%20Gentry%20Articles/

Guests Send Private Message Find Member's Posts Guest Group	Post Options Post Reply Quote Guests Quote Reply Posted: 08 Feb 14 at 8:36am
	Hey... See the 6th word of the second post! ;-) One to avoid - aerohydrodynamics and the performance of sailing yachts by Fossati.

Strangler Send Private Message Find Member's Posts Posting king Joined: 24 Mar 06 Location: United Kingdom Online Status: Offline Posts: 154	Post Options Post Reply Quote Strangler Report Post Quote Reply Posted: 08 Feb 14 at 9:37am