I'm getting a bit fed up now so I'll leave you with this final note. You will struggle to describe 'lift' without resorting to the word pressure and it's roll in accepted physics. However, the processes covering the details of the physical mechanics of the sail and wing can be described successfully with particle, thermal physics and the gas laws. Or indeed totally accounted for by fundamental of physics, the conservation laws and Newtonian mechanics through continuum theory without mentioning
Challenge. If a wing and a sail are, "exactly the same", prop up a vertical wing on your boat and go racing. Or, if you're brave enough put the sails horizontally on your plane and set off down the Tarmac.
How can you attempt to explain the working or necessity for a keel in a sailboat without once referring to it's turning moment and resistance to heel due to it's mass and distance from the centre of gravity. You simplify and dispel again simpler physics in favour of your new pal, 'lift'.
Quote, "a lot log people don't realise that a sail and a wing are exactly the same". Now if I wanted to get 'geeky' about it I would ask why the proof was to use a solid airfoil profile in the tank with no attempt to present a model sail for comparison. The only thing we wanted to see/needed to see was a sail in the tank doing the same thing, with, of course the same angle of attack. If it's real, show that it's real.
Oh, I get it now. Armed with the knowledge that a wing is flown parallel to the airflow (unlike a sail), and stalls if tilted (but the sail can still be used through the stall into full drag), I know exactly what to do. If I pull this, and pull that and release this. Hang on......, it's working, it's working. SEE, EVERYBODY, FLAGS, SEE. I love flags. The biggest, whitest, triangular flags in the bay!
The bloke who blows the paper is obviously the janitor at the institute, as blowing equally across a line of paper mainly illustrates a conservation of momentum in the airflow and better describes how a flag flies
Helisco is correct as well. The pressure is the driving force in fluids. That's where the energy lies and nothing happens without energy. When the pressure drops particle velocities align to produce higher flow (dynamic pressure). The pressure drops because of the sail removing the retaining constriction. This is not the same as saying the speed increases because of the greater path length, so the pressure drops. Nothing sucks (except incorrect descriptions).
The primary thrust vectors of a solid airfoil are always negative. Wings don't push an aircraft forward, they just 'lift' it up. With a big enough engine it would be faster without wings (rocket). The sail shape is formed by the forces on it and the useful thrust is positive. The analogy with lift in many circumstances produces heel in a sailboat. All that is necessary is the basics of momentum exchange, action and reaction, and components of resultant thrust vectors.
The only thing missing in this video is to touch on the undercamber of the sail, versus a flat-bottomed, or symmetrical airfoil on most airplanes. Otherwise, great information. Thanks!
And bam, we're sailing.
cgpilk 2 months ago
Continuation. the word 'lift'.
g1geo1g 3 months ago
I'm getting a bit fed up now so I'll leave you with this final note. You will struggle to describe 'lift' without resorting to the word pressure and it's roll in accepted physics. However, the processes covering the details of the physical mechanics of the sail and wing can be described successfully with particle, thermal physics and the gas laws. Or indeed totally accounted for by fundamental of physics, the conservation laws and Newtonian mechanics through continuum theory without mentioning
g1geo1g 3 months ago
Challenge. If a wing and a sail are, "exactly the same", prop up a vertical wing on your boat and go racing. Or, if you're brave enough put the sails horizontally on your plane and set off down the Tarmac.
g1geo1g 3 months ago
How can you attempt to explain the working or necessity for a keel in a sailboat without once referring to it's turning moment and resistance to heel due to it's mass and distance from the centre of gravity. You simplify and dispel again simpler physics in favour of your new pal, 'lift'.
g1geo1g 3 months ago
Quote, "a lot log people don't realise that a sail and a wing are exactly the same". Now if I wanted to get 'geeky' about it I would ask why the proof was to use a solid airfoil profile in the tank with no attempt to present a model sail for comparison. The only thing we wanted to see/needed to see was a sail in the tank doing the same thing, with, of course the same angle of attack. If it's real, show that it's real.
g1geo1g 3 months ago
Oh, I get it now. Armed with the knowledge that a wing is flown parallel to the airflow (unlike a sail), and stalls if tilted (but the sail can still be used through the stall into full drag), I know exactly what to do. If I pull this, and pull that and release this. Hang on......, it's working, it's working. SEE, EVERYBODY, FLAGS, SEE. I love flags. The biggest, whitest, triangular flags in the bay!
g1geo1g 3 months ago
The bloke who blows the paper is obviously the janitor at the institute, as blowing equally across a line of paper mainly illustrates a conservation of momentum in the airflow and better describes how a flag flies
g1geo1g 3 months ago
Helisco is correct as well. The pressure is the driving force in fluids. That's where the energy lies and nothing happens without energy. When the pressure drops particle velocities align to produce higher flow (dynamic pressure). The pressure drops because of the sail removing the retaining constriction. This is not the same as saying the speed increases because of the greater path length, so the pressure drops. Nothing sucks (except incorrect descriptions).
g1geo1g 3 months ago
The primary thrust vectors of a solid airfoil are always negative. Wings don't push an aircraft forward, they just 'lift' it up. With a big enough engine it would be faster without wings (rocket). The sail shape is formed by the forces on it and the useful thrust is positive. The analogy with lift in many circumstances produces heel in a sailboat. All that is necessary is the basics of momentum exchange, action and reaction, and components of resultant thrust vectors.
g1geo1g 3 months ago
i hate aeronautical engineers!
obaidCarkey 3 months ago
The physics from 3:46 to 4:38 is simply not correct. See the paper at iopscience.iop.org/0031-9120/38/6/001 for the real explanation.
Helisco 4 months ago
how does it works!?
picaticatara 5 months ago
This has been flagged as spam show
The only thing missing in this video is to touch on the undercamber of the sail, versus a flat-bottomed, or symmetrical airfoil on most airplanes. Otherwise, great information. Thanks!
FourDollaRacing 5 months ago
Comment removed
FourDollaRacing 5 months ago
god do like in the old time froget about the shit beind it and just do it
CoolKillerClan 9 months ago
Bad bad bad... I expected the PHYSICS not the HISTORY of sailing.
beeaich 1 year ago
@beeaich how is this not physics?
jenkins0009 1 year ago
@jenkins0009 ...because the bitch didn't watch past the intro!
FourDollaRacing 5 months ago
I learnd a lot from this,Thank you so much!
88horrorfan 1 year ago
Very good vid.
freebeer08 1 year ago 4
Nice production.
Not all pre-modern sailing ships were slow and could only be dragged along with the wind.
Airfoil shaped sails and boats that can sail into the wind have existed since the middle ages.
Even a square sail can move a ship in a vector 90 degrees to the wind.
Most tall ships had special sails to move into the wind.
Most long journeys follwed the trade winds, but if your ship can't be rowed, it has to sail into the wind at some point.
wildblue2 2 years ago 5
Thanks for a really great video primer on sailing !
SailTimeCa 3 years ago
I missed the original broadcast. Thanks for posting this show.
Doug
Oakland, CA
TeleTubeee 3 years ago