modern sails spun off mechanical flight technology?
 

"Scout" wrote in message
. ..
One would think that the sheer volume of air would make its efficient use
a
non-issue. Unless the point is the area of the cross-section of air
available to a given size boat is limited. If that makes any sense.
Scout

The energy availabe to a sailboat is only limited by the area of sail you
put up to catch it and you do not have to worry about extracting all the
energy from the moving air because there is so much of it and it is free.
You want more energy? Hoist a bigger sail.
In a turbine or any motor that requires fuel you have paid for the fuel that
creates the energy and the fuel you have on board is limited in quantity so
of course you have to extract every last bit of energy from it by any
available means.

modern sails spun off mechanical flight technology?
 

"Gilligan" wrote in message
. ..

"Scout" wrote in message
. ..
"DSK" wrote in message
. ..
I guess once people got the idea of fluid movement around restrictions
creating usable pressure differentials, it became just a matter of
experimenting with different shapes and fluids.

When you say "experimenting with different fluids" do you mean like
sulfur dioxide? Does it increase or decrease the efficiency of sails?




Think of this. The sail has the most power delivered to it when the
residual wind velocity is zero after interacting with the sail.


I think that's a mistaken assumption. The sail has the most power
delivered to it when it is developing max differential pressure
theoretically possible for it's density & initial velocity.



The most efficient sail design reuses the wind velocity, similar to the
stages on a turbine engine.


True. That's why the America's Cup racers all have to be limited by rule
as for how many masts they can rig. It got to be a PITA inventing new
terms for the fifteenth & sixteenth mizzen.


The most efficient sail design of all time was developed in Northern
Italy. The design was lost during the early Renaissance, only to be
recently uncovered during and archeological dig in a shallow bay. The
sails reused the wind many times over with each "stage" adjusted for
the reduced wind velocity. The sails are a series of "slats" with
multiple gaps and adjustable angles of attack. They are referred to as
Venetian Sails.


Now that was a very illuminating little essay



Scout wrote:
One would think that the sheer volume of air would make its efficient
use a non-issue. Unless the point is the area of the cross-section of
air available to a given size boat is limited. If that makes any sense.

Congrats, you've re-invented the term "sail area" ;)

Fresh Breezes- Doug King

Welcome back Doug!
By "experimenting with different fluids" I meant air and water, but in
Gilly's case, he may need to understand the subtleties of sulfur sailing
on the lava lakes!
Scout

Don't forget lava can be considered a liquid too.

Hmmm, what might make a good hull material for floating on lava? The temp of
lava? 2000+ F?
http://volcano.und.edu/vwdocs/freque...stion3620.html

I'd go with a hull made of Carbon, Tungsten, or Rhenium, in that order!
http://www.lenntech.com/Periodic-cha...ting-point.htm

Should be heavy too, don't you think? Lots of ballast or she'll roll right
over in such a dense sea. But not lead in that keel, the fumes will get you
high, permanently!
Scout

modern sails spun off mechanical flight technology?
 

"Edgar" wrote in message
. ..

"Scout" wrote in message
. ..
One would think that the sheer volume of air would make its efficient
use
a
non-issue. Unless the point is the area of the cross-section of air
available to a given size boat is limited. If that makes any sense.
Scout

The energy availabe to a sailboat is only limited by the area of sail you
put up to catch it and you do not have to worry about extracting all the
energy from the moving air because there is so much of it and it is free.
You want more energy? Hoist a bigger sail.
In a turbine or any motor that requires fuel you have paid for the fuel
that
creates the energy and the fuel you have on board is limited in quantity
so
of course you have to extract every last bit of energy from it by any
available means.

Edgar, that's pretty much what I was trying to say. By increasing the sail
size, you increase the area of the cross-section of air available. But given
the restriction of a limited (practical) sail square footage, I would
imagine it a benefit to capture more of the available energy using the
concept proposed by the Italians, per Gilligan. Not sure if it's worth the
effort, but it might be.
Scout

modern sails spun off mechanical flight technology?
 

"DSK" wrote in message
. ..


The most efficient sail design of all time was developed in Northern
Italy. The design was lost during the early Renaissance, only to be
recently uncovered during and archeological dig in a shallow bay. The
sails reused the wind many times over with each "stage" adjusted for the
reduced wind velocity. The sails are a series of "slats" with multiple
gaps and adjustable angles of attack. They are referred to as Venetian
Sails.


Now that was a very illuminating little essay


http://dibinst.mit.edu/DIBNER/Rhodes/ships_sailing.html

modern sails spun off mechanical flight technology?
 

Now that was a very illuminating little essay


Gilligan wrote:
http://dibinst.mit.edu/DIBNER/Rhodes/ships_sailing.html


Awesome website... thanks very much for posting this link!

It's not an illuminated manuscript though.

DSK

modern sails spun off mechanical flight technology?
 

Gilligan wrote:
The USS Constitution demonstrated that in light air, the speed of the ship
could be increased by spraying water on the sails.

Documented he

http://www.history.navy.mil/photos/e...a/const-es.htm


Sure. Well known and oft-practiced trick for getting a bit
of speed out of natural fabric sails. I don't know when it
was first used, possibly back when they started weaving
cloth strong enough that sails no longer needed leather
reinforcing strips (the Viking Age tape-drive laminate).






Think of this. The sail has the most power delivered to it when the
residual wind velocity is zero after interacting with the sail.


I think that's a mistaken assumption. The sail has the most power
delivered to it when it is developing max differential pressure
theoretically possible for it's density & initial velocity.


The maximum pressure differential occurs for any given windspeed when the
airspeed on the low pressure side of the sail is zero.

No, the maximum differential pressure possible is when the
LP side is a vacuum. Velocity can produce pressures lower
than ambient; air that is sitting still cannot.


.... If the velocity on
the "low pressure side" equals the velocity on the high pressure side there
is no lift.


C'mon, you're not thinking in vectors! What if that velocity
is equal to, or faster, than on the HP side and in a
different direction?

DSK

modern sails spun off mechanical flight technology?
 

"DSK" wrote in message
.. .
Gilligan wrote:
The USS Constitution demonstrated that in light air, the speed of the
ship could be increased by spraying water on the sails.

Documented he

http://www.history.navy.mil/photos/e...a/const-es.htm


Sure. Well known and oft-practiced trick for getting a bit of speed out of
natural fabric sails. I don't know when it was first used, possibly back
when they started weaving cloth strong enough that sails no longer needed
leather reinforcing strips (the Viking Age tape-drive laminate).


I do it regularly in strong winds. Even get the tippy top part of the sail
wet.








Think of this. The sail has the most power delivered to it when the
residual wind velocity is zero after interacting with the sail.


I think that's a mistaken assumption. The sail has the most power
delivered to it when it is developing max differential pressure
theoretically possible for it's density & initial velocity.


The maximum pressure differential occurs for any given windspeed when the
airspeed on the low pressure side of the sail is zero.

No, the maximum differential pressure possible is when the LP side is a
vacuum. Velocity can produce pressures lower than ambient; air that is
sitting still cannot.

You're right.



.... If the velocity on the "low pressure side" equals the velocity on
the high pressure side there is no lift.


C'mon, you're not thinking in vectors! What if that velocity is equal to,
or faster, than on the HP side and in a different direction?

Can't it act only normal to the surface?



DSK

modern sails spun off mechanical flight technology?
 

"DSK" wrote in message
.. .
Now that was a very illuminating little essay


Gilligan wrote:
http://dibinst.mit.edu/DIBNER/Rhodes/ships_sailing.html

Awesome website... thanks very much for posting this link!

It's not an illuminated manuscript though.

DSK


I did find a good example of a "Venetian Sail", but it was made in Canada.

modern sails spun off mechanical flight technology?
 

Gilligan wrote:
....

http://www.history.navy.mil/photos/e...a/const-es.htm

Not only that the USS Constitution clearly demonstrated she could sail
directly into the wind:

http://www.americanheritage.com/arti...955_3_56.shtml

I didn't see that mentioned - where was it?


If that is not enough, here the USS Constitution is the first US warship to
to have propellers:

http://www.usni.org/navalhistory/art...ingtonApr.html


Not propellers, human powered paddlewheels.

modern sails spun off mechanical flight technology?
 

"Jeff" wrote in message
. ..
Gilligan wrote:
...

http://www.history.navy.mil/photos/e...a/const-es.htm

Not only that the USS Constitution clearly demonstrated she could sail
directly into the wind:

http://www.americanheritage.com/arti...955_3_56.shtml

I didn't see that mentioned - where was it?

Sailing backwards.



If that is not enough, here the USS Constitution is the first US warship
to to have propellers:

http://www.usni.org/navalhistory/art...ingtonApr.html


Not propellers, human powered paddlewheels.