Axel

First please realize that the brother Wright had to reinvent
aerodymanics whent hey found out the all the material that they had
collected was junk. (Mr. langley didn't like them very much.) They
were also the first people to build and used a wind tunnel (they built
three in total) to any advantage.

The "sail as a foil" convention can not really be tied down easily, but
the oldest paper in my library is from the mid-teens and contains some
things that are now known to be in error. A book that I have was
written in the mid-twenties and it is hard to tell the difference
between the going to weather part of this book and my newer ones.

From the things that I was taught by much older people about a half a
century ago, the understanding of the function both square and
fore-and-aft rigged sails is not recent, but the language to describe it
is (realiviely).

Matt Colie
Lifelong Waterman, Licensed Mariner and Perpetual Sailor

Axel Boldt wrote:
Thanks a lot for the illuminating answers. I read somewhere that the
"sail-as-airfoil" trick is a rather recent one, and that formerly
people would just let the wind push them around. Is that true, and if
yes, how recent is the invention?

Thanks,
Axel

John,

This is a common mis-conception.

The truth is that most merchant vessels could do only do 160 deg between
tacks, but many other square sails could do well better than that. It
just took a lot of manpower and money to handle the extra rigging that
would tighten the luff. Vikings with wool sails reports taht they could
manage about 120 and that was not equaled until the fore and aft
rigged schooners appeared in the early nineteenth century.

Matt Colie
Lifelong Waterman, Licensed Mariner and Perpetual Sailor


John Weiss wrote:

Square-rigged boats could sail no higher than a beam reach. However, the sails
were not flat, and they were trimmed appropriately to allow the boats to be
sailed other than dead downwind.

I don't recall the date triangular sails were invented, but they were the dawn
of upwind sailing in the west; junk rigs enabled upwind sailing in the east.

"Axel Boldt" wrote...

Thanks a lot for the illuminating answers. I read somewhere that the
"sail-as-airfoil" trick is a rather recent one, and that formerly
people would just let the wind push them around. Is that true, and if
yes, how recent is the invention?

Jax,
Maybe I didn't word it clearly. I said "A boat goes to windward by
generating lift from its sail, just like an aircraft's wing. If you
understand a wing you are 3/4 of the way there."

I meant 3/4 of the way towards understanding how a boat goes to windward
- not 3/4 of understanding sail airfoils. The other 1/4 being to turn
it on its end and match it with a keel, centreboard etc.

But this isn't helping Axel very much. Do you know of any good online
diagrams we could point him at? I admit I can't be bothered to search
for one...

And.

JAXAshby wrote:

my statement was in respone to the secondary posting that said understanding
wing arifoils was 3/4 of understanding sail airfoils.

andy, lift is lift. airfoil or water foil or ethylenglchol or methanol or
whatever.

Jax,
Maybe I didn't word it clearly. I said "A boat goes to windward by
generating lift from its sail, just like an aircraft's wing. If you
understand a wing you are 3/4 of the way there."

I meant 3/4 of the way towards understanding how a boat goes to windward
- not 3/4 of understanding sail airfoils. The other 1/4 being to turn
it on its end and match it with a keel, centreboard etc.

But this isn't helping Axel very much. Do you know of any good online
diagrams we could point him at? I admit I can't be bothered to search
for one...

And.

JAXAshby wrote:

my statement was in respone to the secondary posting that said
understanding
wing arifoils was 3/4 of understanding sail airfoils.

On 16 Aug 2004 01:38:25 GMT, (JAXAshby) wrote:

andy, lift is lift. airfoil or water foil or ethylenglchol or methanol or
whatever.


Sails are asymmetrical, keels are symmetrical.

Makes a difference.

But to sail upwind effectively you need both sails and a keel. Ergo -
sails are not 100%. Downwind is another issue. I watch Lasers raise
their keels on a leeward leg.


Jack
__________________________________________________
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
Phone: 1 (877) 470-SAIL (toll free)
__________________________________________________

jack, you also need air breath, a hull that floats, a rudder, sunscreen
protection and maybe condoms if you might get lucky.

However, none of those in anyway affect how the airfoil on a sail works, which
is 100% the same as the way the the airfoil on a wing works.

andy, lift is lift. airfoil or water foil or ethylenglchol or methanol or
whatever.


Sails are asymmetrical, keels are symmetrical.

Makes a difference.

But to sail upwind effectively you need both sails and a keel. Ergo -
sails are not 100%. Downwind is another issue. I watch Lasers raise
their keels on a leeward leg.


Jack
_________________________________________________ _
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
Phone: 1 (877) 470-SAIL (toll free)
_________________________________________________ _

You guys are getting boring. Maybe the two of you can get together by
ganging up on me!

:-)


"JAXAshby" wrote in message
...
jack, you also need air breath, a hull that floats, a rudder, sunscreen
protection and maybe condoms if you might get lucky.

However, none of those in anyway affect how the airfoil on a sail works,
which
is 100% the same as the way the the airfoil on a wing works.

andy, lift is lift. airfoil or water foil or ethylenglchol or methanol
or
whatever.


Sails are asymmetrical, keels are symmetrical.

Makes a difference.

But to sail upwind effectively you need both sails and a keel. Ergo -
sails are not 100%. Downwind is another issue. I watch Lasers raise
their keels on a leeward leg.


Jack
_________________________________________________ _
Jack Dale
Swiftsure Sailing Academy
Director/ISPA and CYA Instructor
http://www.swiftsuresailing.com
Phone: 1 (877) 470-SAIL (toll free)
_________________________________________________ _

The invention goes back at least as far as the "Boomarang", Chinese Junk
Rig, Lateen Rig, Polynesian Claw Sail; All before the time of Common
Age. The Europeans didn't have knowledge of it until 1000's of years
later

Ole Thom

Hey Guys,

Don't you know Jax well enough by now. If he has an answer, he'll sure
hell modify the question to fit his answer. Re-quoting the original
question does absolutely no good.

OT

if you know the olde fart well enough, you notice olde thom doesn't make much
sense in any post after about 4:00 in the afternoon.

From: (Thom Stewart)
Date: 8/17/2004 ------------------ 10:26 PM -------------------- Eastern
Daylight Time
Message-id:

Hey Guys,

Don't you know Jax well enough by now. If he has an answer, he'll sure
hell modify the question to fit his answer. Re-quoting the original
question does absolutely no good.

OT