Sail Aerodynamics
 

what word didn't you understand, dougie?

But he did not answer either question meaningfully.

DSK

Sail Aerodynamics
 

JAXAshby wrote:

what word didn't you understand,

The "yes" and "no" answers to essay questions.

BTW got any investment advice? We're all ears, and I'm sure your new pal
MC would like some pointers.

DSK

Sail Aerodynamics
 

you asked a question, and yes or no were the correct answers.

as far as investment advice goes I can only repeat the advice of Will Rogers.
"Buy and when the stock goes up, sell. If it doesn't go up, don't buy".

JAXAshby wrote:

what word didn't you understand,

The "yes" and "no" answers to essay questions.

BTW got any investment advice? We're all ears, and I'm sure your new pal
MC would like some pointers.

DSK

Sail Aerodynamics
 

JAXAshby wrote:
you asked a question,

No, I asked at least two. I knew you were math-impaired, but I didn't
realize that you could not count to two!

.... and yes or no were the correct answers.

If that is true (seems unlikely in view of your knowledge level) then
please explain why.

DSK

Sail Aerodynamics
 

dougie, the tip vortex comes about because the pressure on the windward side of
the sail is greater than on the leeward side. The greater pressure tries to
make it to the lower pressure. the air on the heavy side rolls over the aft
edge of the sail in the easiest possible manner, which includes going up as
well as back. This makes for the vortex as the aft edge of the sail meets the
forward edge.

having a main sail downwind of the jib does not cause the jib airflow to stop
trying to go from high pressure to low pressure. The vortex generated causes
turbulant air from the jib to screw up the airflow across the main. moving the
top of the jib lower than top of the main just causes the jib vortex to hit
more of the main.

okay?


JAXAshby wrote:
you asked a question,

No, I asked at least two. I knew you were math-impaired, but I didn't
realize that you could not count to two!

.... and yes or no were the correct answers.

If that is true (seems unlikely in view of your knowledge level) then
please explain why.

DSK

Sail Aerodynamics
 

JAXAshby wrote:

dougie, the tip vortex comes about because the pressure on the windward side of
the sail is greater than on the leeward side. The greater pressure tries to
make it to the lower pressure. the air on the heavy side rolls over the aft
edge of the sail in the easiest possible manner, which includes going up as
well as back. This makes for the vortex as the aft edge of the sail meets the
forward edge.

A little slower, Jax... Navvie is taking notes...

You have got part of the explanation of tip vortex, so far so good. But if what you
say is all there is, then why are there not a series of vortexes all along the
trailing edge instead of just at the tip? Of course, when the flow is just
starting, that's true, but after flow is established there is just a vortex at the
tip.

Another thing to account for is vertical pressure distribution.





having a main sail downwind of the jib does not cause the jib airflow to stop
trying to go from high pressure to low pressure. The vortex generated causes
turbulant air from the jib to screw up the airflow across the main. moving the
top of the jib lower than top of the main just causes the jib vortex to hit
more of the main.

okay?

But that doesn't answer the earler question... the differential pressure across the
main is going to interfere with (and suppress) the tip vortex from the jib. Got it
so far? That means that energy lost through the jib head tip vortex will be less.

Now, is that energy gain for a frac rig greater or less than the gain a masthead
rig gets from not having the jib head tip vortex disrupting flow across the main?

Folks, I think Jax *might* begin to actually grasp the question this time.... any
bets?

Fresh Breezes- Doug King

Sail Aerodynamics
 

DSK wrote:

JAXAshby wrote:


dougie, the tip vortex comes about because the pressure on the windward side of
the sail is greater than on the leeward side. The greater pressure tries to
make it to the lower pressure. the air on the heavy side rolls over the aft
edge of the sail in the easiest possible manner, which includes going up as
well as back. This makes for the vortex as the aft edge of the sail meets the
forward edge.


A little slower, Jax... Navvie is taking notes...

You have got part of the explanation of tip vortex, so far so good. But if what you
say is all there is, then why are there not a series of vortexes all along the
trailing edge instead of just at the tip? Of course, when the flow is just
starting, that's true, but after flow is established there is just a vortex at the
tip.

Another thing to account for is vertical pressure distribution.





having a main sail downwind of the jib does not cause the jib airflow to stop
trying to go from high pressure to low pressure. The vortex generated causes
turbulant air from the jib to screw up the airflow across the main. moving the
top of the jib lower than top of the main just causes the jib vortex to hit
more of the main.

okay?


But that doesn't answer the earler question... the differential pressure across the
main is going to interfere with (and suppress) the tip vortex from the jib. Got it
so far? That means that energy lost through the jib head tip vortex will be less.

Now, is that energy gain for a frac rig greater or less than the gain a masthead
rig gets from not having the jib head tip vortex disrupting flow across the main?

Folks, I think Jax *might* begin to actually grasp the question this time.... any
bets?


I'll bet you haven't got a clue what you are talking about. It was you
who didn't know where the greatest pressure on the main was wasn't it?
Your earlier comments also show you don't even begin to understand the
relationship between constructing an effective eliptical planaform by
controlling draft position.

Cheers

Sail Aerodynamics
 

MC wrote:


I'll bet you haven't got a clue what you are talking about.

If I haven't got a clue, then you should be able to easily show the mistakes in my post
above.


It was you
who didn't know where the greatest pressure on the main was wasn't it?

where did you get that idea? In any event, pressure distribution will be different under
different conditions.


Your earlier comments also show you don't even begin to understand the
relationship between constructing an effective eliptical planaform by
controlling draft position.

Maybe not. Go ahead and explain it clearly.

Oh, and fully answer the question from the above post.

DSK

Sail Aerodynamics
 

DSK wrote:

MC wrote:


I'll bet you haven't got a clue what you are talking about.


If I haven't got a clue, then you should be able to easily show the mistakes in my post
above.



It was you
who didn't know where the greatest pressure on the main was wasn't it?


where did you get that idea? In any event, pressure distribution will be different under
different conditions.


Your earlier comments also show you don't even begin to understand the
relationship between constructing an effective eliptical planaform by
controlling draft position.


Maybe not. Go ahead and explain it clearly.

Oh, and fully answer the question from the above post.


I will if you'll admit you don't know why the vortex forms


Cheers

Sail Aerodynamics
 

DSK wrote:

MC wrote:


I'll bet you haven't got a clue what you are talking about.


If I haven't got a clue, then you should be able to easily show the mistakes in my post
above.



Your mistake is you you thinking you had posted anything except a series
of questions. In fact, this is correct in so far as it shows that you
don't know what you are talking about -as I pointed out.

Cheers