Settle an argument

[noelex 77]

Originally Posted by Adelie

Even in a aerobatic plane the range would be significantly decreased, the angle of attack for the fuselage and empenage would be significantly changed.

Some modern aerobatic aircraft have 0,0,0 rigging (0 degrees wing incidence, tail incidence, dihedral) and of course a symetrical aerofoil.

[SURV69]

Unless this is a "really friendly", argument . . . you can't win . . . don't try to win.

Give him a book about sailing and invite him to sail with you.

[Hudson Force]

Originally Posted by Bash

.............The real question isn't science--it's engineering: just how are you going to keep a flat sail flat?

I'm totally lost with this,- "... isn't science--it's engineering". That's like saying it isn't a bird--it's a duck!

[jongleur]

I know of no birds whose wings are not...well...wing shaped. I wonder, why is that?

[noelex 77]

Originally Posted by SURV69

Unless this is a "really friendly", argument . . . you can't win . . . don't try to win.

If the argument gets difficult, just say "everything is great in bedroom" . I bet FIL changes the subject to the weather, sport, or politics

[Wotname]

Originally Posted by Tscott8201

Ok, had a friendly argument with my father in law this weekend. Last time we rented a sailboat for a day the instructor commented on the importance of sail trimming due to the fact the sail is basically a wing. Later on that day my father in law brings up that he believes this is all mumbo jumbo and that the "wing effect" is basically oversold. He claims that a perfectly workable sail could be made out of a flat solid sheet of material with no curve and you would get decent performance out of it. Not as good a a curved sail, but almost as good. I told him it might work but would basically be crap and give little to no forward thrust. Who is right?

Tom

Originally Posted by Adelie

Sailing dead downwind, FIL is 70% right, a cupped shape will provide more drive downwind than a flat plate.

Hmm... 70% can be considered in some circumstances as "almost" so I maintain FIL was 100% correct in his assessment when DDW.

Originally Posted by Cheechako

Never argue with the FIL, even when he's wrong as in this case!

Originally Posted by noelex 77

If the argument gets difficult, just say "everything is great in bedroom" . I bet FIL changes the subject to the weather, sport, or politics

Which brings us to the question "who / what does the significant daughter believe"?

[RainDog]

Flying Lawnmower - YouTube

[perchance]

Originally Posted by Adelie

Huh?!?

The CF 104 Starfighter was basically a big jet engine with stubby thin wings and razor sharp leading edges which proved that even a brick will develope lift if you move it fast enough.

[DutchAW]

The sail does act like a wing, it's basic physics. High pressure air going over the outside of the sail meets lower pressured air on the back side of the sail resulting in a vacuum that creates lift. Works the same whether your sail/wing is horizontal or vertical. Of course sailing directly downwind is another story. Oh it's called Bernoulli's Principle if anyone would care to look it up. I'm not smart enough for all the math, but the basics are solid.

[Bash]

Originally Posted by CaptForce

I'm totally lost with this,- "... isn't science--it's engineering".

Thinking of the latter as the application of the former.

Why sails shaped as airfoils are faster than flat sails is a science question.

How to maintain specific airfoil shapes would be an engineering question.

[goboatingnow]

Originally Posted by DutchAW

The sail does act like a wing, it's basic physics. High pressure air going over the outside of the sail meets lower pressured air on the back side of the sail resulting in a vacuum that creates lift. Works the same whether your sail/wing is horizontal or vertical. Of course sailing directly downwind is another story. Oh it's called Bernoulli's Principle if anyone would care to look it up. I'm not smart enough for all the math, but the basics are solid.

Bernoulli's principles used to explain flight have large been debunked

Have read of http://www.grc.nasa.gov/WWW/k-12/airplane/wrong1.html

It's all about vortexes and turning the fluid , FIL is right, lift would be generated using a flat sail, say one made out of rigid composite material, not as efficient as a foil of course.

Dave

[tropicalescape]

Originally Posted by cal40john

I am very confused. Are you saying the link I posted had anything to do with Bernoulli, because it doesn't.

Part 11 other theories...

[Adelie]

Originally Posted by cfarrar

True, but most sailboats are symmetrical. Ie, they are not designed to create greater lift on one tack than the other. So, FIL is mostly correct, after all!

The whole plane thing was thread drift very tenuously related to the OP's question.

The symmetry of a sailboat has no bearing on whether flat plate will perform just as well when substituting for a sail with draft.

[Adelie]

Originally Posted by RainDog

Just goes to show you that if you apply enough power anything will fly.

There was once an F-15 that lost a wing. Pilot landed the plane just on the lift provided by the fuselage.

[Adelie]

Originally Posted by perchance

The CF 104 Starfighter was basically a big jet engine with stubby thin wings and razor sharp leading edges which proved that even a brick will develope lift if you move it fast enough.

The apparent non-sequitor baffled me.

Actually it was the trailing edges that were razor sharp, though the leading edges were also sharp enough to cut.