A taste of things to come...

[Roy Stewart]

In fact Bernoulli's theory and Newtonian physics explain lift, they give the same answer, namely that a flat plate will create lift.

A flat plate moving underwater creates no lift unless there is an angle of attack, as above. It is bad science to mention only half of a theory to support an idea.

I didn't, the quote which you took came after an explanation of when flate plates create lift, so your accusation is misleading, and factually false.

Keep in mind that you had just finished telling me the untruth that flat plates cannot create lift as only wings which are curved on top create lift.

Obviously ALL wings require an angle of attack in order to create lift. You need to understand that. It's elementary !

If it moves while facing horizontally, there is no lift as the forces are identical top and bottom (gravity and buoyancy ignored).

There are two types of lift, the first is that which is created by an angled fin (or the hull of the surfboard) physically pushing the water down as it moves through it. Whether it is a fin or the board, the mechanic of lift is the same, Newtons 3rd all over again.

The second is the sucking lift generated by bernoulli's principle, which requires a foiled upper half of the fin. That is the same principle of suction force that is created by turbulence, which occurs when the angle of attack of the fin is great enough. I think you may have misunderstood the principle yourself.

Wrong

What you are describing are not two different kinds of lift but a single phenomenon (or 'one kind of lift' ) explained by two different theories.

Both Bernoulli's theory and Newtonian physics arrive at the same answers

Until you understand this and a few other points I won't be able to explain the more interesting aspects of tunnel fin behaviour.

By the way you are 100% incorrect in stating that 'sucking' lift as explained by Bernoulli requires a wing which is foiled or curved on top. In fact Bernoulli's theroem explains perfectly why such lift is produced by a flat plate..

Your mistakes are typical of those who were taught physics in high school, those school teacher parrots have a lot to answer for !

I would like you to explain in detail please, because at the moment the burden of proof lies with you. It is no use throwing out the names of a few well known principles unless you actually back it up by saying HOW it relates to what you are saying. At the moment it is all talk without the punch, so to speak.

That's pretty rich coming from someone who only a post ago thought that flat plates can't create lift. I've been attempting to explain to you what's going on but your undertanding is full of myths and misconceptions which I'm doing my best to clear up for you. Some of your sentences are ambiguous which makes them difficult to respond to.

The accusation that I'm merely name dropping is complete nonsense, just do some research and you'll find that what I'm saying about Bernoullian and Newtonian treatment of lift is correct. The only reason I brought it up is because you eroneously stated that a tunnel fin could not produce lift unless it is 'curved' on top. .. which is utter nonsense.

Now regarding lift, a tunnel fin or submerged foil will lift against the surfboard hull adjacent to the fin even if it is set up with an apparent angle of attack which is parallel to the hull. See if you can figure out why for your homework ! It's a very important point and it is also relevant to the superior lift drag ratio of the submerged foil.

Then perhaps we can get into high and low pressure zones on the hull, and how the fin alters those.

After that, (if you are still speaking to me) the benefits of flex for boards with horizontal fin area and why they are greater than for flexible boards without horizontal fin area can be discussed.

Then there is the misunderstanding of annular wing lift in the standard literature and how this occured due to an anomaly in the measurement of lift and in the comparison and measurement of annular wing vs planar wing area.

We mustn't forget the fact that half pipe tunnels produce a beneficial vortex whenever the board turns, nor the fact that I've tested the tunnel finned boards over a 13 year period and have achieved remarkable speeds on them ( 37+mph in weak head high beach break waves, faster by 12 mph than the top 40 got in a recent speed test in better waves at snapper rocks.) They also have perfect handling characteristics.

They are definitely going to be the fin of the future, but I'm in no hurry for them to become mainstream, as they give me a huge advantage against the outdated multi fin systems in general use.

By the way there's only one person who is 'all talk' in this conversation, and it isn't me.... I've been doing it with half pipe tunnel fins physically i.e. in the water testing for 13 years, as stated, whereas (unless I am mistaken ) you have not .

http://olosurfer-woodensurfboardsatpipeline.blogspot.com/





.

[Rickyroughneck]

That's pretty rich coming from someone who only a post ago thought that flat plates can't create lift.

Not if presented horizontally to the flow. If you believe that to be the case then you may benefit from some high school physics yourself. I should have been clearer first time around, but I stated "passing a plane underwater creates no lift". I assumed the horizontal element of your fins are parallel to the board hull at the point of attachment (which they are), in which case the angle of the fin is parallel to the flow. Hence no lift.

For the fin to generate lift in the way you describe, the water would have to move towards the board (not just around it), which is a silly notion. If water did actively move towards the surfboard, that would be because the surfboard exerted a force on it (such as the sucking force by those noseriders you love)! That same force (Newtons third) would drive the surfboard down which is counter-productive to drag. Lift is generated by the surfboard pushing water DOWN, not up.

Obviously ALL wings require an angle of attack in order to create lift. You need to understand that. It's elementary !

Actually no, foiled wings create Bernoulli's lift even when presented parallel to the direction of travel. The forces are small compared to "Newton's" lift so there is an optimum angle for lift-drag at about 5 degrees where the wing benefits from both types of lift (it varies from wing to wing, as well as with speed).

Now regarding lift, a tunnel fin or submerged foil will lift against the surfboard hull adjacent to the fin even if it is set up with an apparent angle of attack which is parallel to the hull. See if you can figure out why for your homework !

Contradiction to the above. Your words, not mine. You've certainly done your homework, but did you get it marked? - What was the result?

Wrong

What you are describing are not two different kinds of lift but a single phenomenon (or 'one kind of lift' ) explained by two different theories.

Both Bernoulli's theory and Newtonian physics arrive at the same answers

In a sense, all physics up to the quantum level is the same. It all fits together like a jigsaw (not those crappy free ones you get in Christmas crackers which don't fit very well). So in a sense, Bernoulli and Newton arrive at the same answer, (pressure). That said, pressure can explain all the physical forces in the world, it would be pedantic to drive that point beyond what you have done already.

Talking in real world terms now, Bernoulli's principle, and the Newtonian third are different methods of lift. Bernouilli's is the sucking lift, caused by reduction in pressure on the upper edge caused by water moving at increased speeds. Newtonian's third is the downwards force presented by a fin with an angle of attack. They are not the same. You can of course explain the other mechanic with the opposite theory (water moves slowly underneath providing a greater force, and the fast moving water has less contact force with the upper surface), but it is sloppy and unclear to do so.

They are definitely going to be the fin of the future, but I'm in no hurry for them to become mainstream, as they give me a huge advantage against the outdated multi fin systems in general use.

Perhaps. If they truly provided the advantages you claimed, then we would have seen them on the mass market years ago as "the next big thing". There is a lot of marketing in surfing, and a lot of barstardisation of design in favour of aesthetics. However if tunnel fins really presented such a huge advantage then shapers would have capitalised on that. The fact that they have barely been seen over all these years, and that modern tunnels are only fleetingly being touched on, suggest that the advantage presented is either non-existent, or marginal enough that the popularity isn't contagious.

I've been attempting to explain to you what's going on but your undertanding is full of myths and misconceptions which I'm doing my best to clear up for you. Some of your sentences are ambiguous which makes them difficult to respond to.

You are not clearing anything up. In most cases you are saying "you are wrong" without offering an alternative. I am sorry if my sentences are ambiguous, I am trying my best to be clear (always imperative in scientific discussion). Please understand that the feeling is mutual. In a lot of cases I think we both could benefit from a clearer writing style.

By the way there's only one person who is 'all talk' in this conversation, and it isn't me.... I've been doing it with half pipe tunnel fins physically i.e. in the water testing for 13 years, as stated, whereas (unless I am mistaken ) you have not .

You are correct in that I haven't. But it is all too easy in science to arrive at the wrong conclusion (especially when you are looking for one) when your method of testing is imprecise, inaccurate and not easily repeatable.

Try actually recording your speed with two high res cameras positioned stationary on the beach to give you accurate bearings against time. Change ONLY the fin type (not the board) and repeat it enough times to build enough data for decent statistical analysis. At a rough estimate, given the variable nature of waves, you will need AT LEAST 1000 waves with each fin type. You will need to compare the speeds using adequate statistical analysis, (pearsons and t-test should e adequate) to ensure that there is significant different in speeds, and that the data did not occur by chance.

You could also do a week of intensive testing in flow tunnels, with the forces at play carefully measured by instruments. Change the fin types and see how that changes the lift. The need for repeats is less apparent in a controlled environment, but try comparing fin size, location, shape.

Until you do the above, your "research" is worth very little indeed. 13 years is worth very little, especially as you did not state how much of that time was spent actually testing tunnel finned boards. There are research investigations that go on for 20 years or over with multiple people on a team that arrive at less definite conclusions.

Until you understand this and a few other points I won't be able to explain the more interesting aspects of tunnel fin behaviour.

Please do.

Then perhaps we can get into high and low pressure zones on the hull, and how the fin alters those.

After that, (if you are still speaking to me) the benefits of flex for boards with horizontal fin area and why they are greater than for flexible boards without horizontal fin area can be discussed.

A bit off topic, but the topic is yours, your call. I would be interested.


Nice looking board.

[Roy Stewart]

That's pretty rich coming from someone who only a post ago thought that flat plates can't create lift.

Not if presented horizontally to the flow. If you believe that to be the case then you may benefit from some high school physics yourself. I should have been clearer first time around, but I stated "passing a plane underwater creates no lift".

.. which is false.
'
I can only respond to what you actually say.

I assumed the horizontal element of your fins are parallel to the board hull at the point of attachment (which they are), in which case the angle of the fin is parallel to the flow. Hence no lift.

Absolutely incorrect.

As stated previously a wing set up parallel to the bottom does produce lift. . . and plenty of it !

Your assumption that my tunnels are always set up parallel is also absolutely incorrect. Sometimes they are and sometimes they are not. In all cases they create lift.

I've written thousands of words over the past decade describing the angles of attack of my tunnel fins in relation to the bottom... some of which are on this forum.

Obviously ALL wings require an angle of attack in order to create lift. You need to understand that. It's elementary !

Actually no, foiled wings create Bernoulli's lift even when presented parallel to the direction of travel. The forces are small compared to "Newton's" lift so there is an optimum angle for lift-drag at about 5 degrees where the wing benefits from both types of lift (it varies from wing to wing, as well as with speed).

Now regarding lift, a tunnel fin or submerged foil will lift against the surfboard hull adjacent to the fin even if it is set up with an apparent angle of attack which is parallel to the hull. See if you can figure out why for your homework !

Contradiction to the above. Your words, not mine. You've certainly done your homework, but did you get it marked? - What was the result?

The two statements are consistent.. there is no contradiction.

You are mistakenly assuming ( again) that a wing which is set up parallel to the bottom has zero angle of attack.

In fact a wing set up parallel to the bottom has a positive angle of attack, particularly but not only in the case of enclosed annular wing systems which have infinite effective span.

I can explain why in detail if you wish.

Wrong

What you are describing are not two different kinds of lift but a single phenomenon (or 'one kind of lift' ) explained by two different theories.

Both Bernoulli's theory and Newtonian physics arrive at the same answers

Talking in real world terms now, Bernoulli's principle, and the Newtonian third are different methods of lift. Bernouilli's is the sucking lift, caused by reduction in pressure on the upper edge caused by water moving at increased speeds. Newtonian's third is the downwards force presented by a fin with an angle of attack. They are not the same.

Incorrect.

They are the same phenomenon explained in two different ways.

Please research the matter you will find that I am correct.

Until you do so the discussion will go nowhwere

They are definitely going to be the fin of the future, but I'm in no hurry for them to become mainstream, as they give me a huge advantage against the outdated multi fin systems in general use.

Perhaps. If they truly provided the advantages you claimed, then we would have seen them on the mass market years ago as "the next big thing". There is a lot of marketing in surfing, and a lot of barstardisation of design in favour of aesthetics. However if tunnel fins really presented such a huge advantage then shapers would have capitalised on that. The fact that they have barely been seen over all these years, and that modern tunnels are only fleetingly being touched on, suggest that the advantage presented is either non-existent, or marginal enough that the popularity isn't contagious.

bull to that !

I know what tunnels do, and the act that the mass market hasn't adopted tunnels does not in any way negate their value.

The argument you use is a logically fallacious one, do some research on logical fallacies in arument please.

I've been attempting to explain to you what's going on but your undertanding is full of myths and misconceptions which I'm doing my best to clear up for you. Some of your sentences are ambiguous which makes them difficult to respond to.

You are not clearing anything up. In most cases you are saying "you are wrong" without offering an alternative. I am sorry if my sentences are ambiguous, I am trying my best to be clear (always imperative in scientific discussion). Please understand that the feeling is mutual. In a lot of cases I think we both could benefit from a clearer writing style.

By the way there's only one person who is 'all talk' in this conversation, and it isn't me.... I've been doing it with half pipe tunnel fins physically i.e. in the water testing for 13 years, as stated, whereas (unless I am mistaken ) you have not .

You are correct in that I haven't. But it is all too easy in science to arrive at the wrong conclusion (especially when you are looking for one) when your method of testing is imprecise, inaccurate and not easily repeatable.

Try actually recording your speed with two high res cameras positioned stationary on the beach to give you accurate bearings against time. Change ONLY the fin type (not the board) and repeat it enough times to build enough data for decent statistical analysis. At a rough estimate, given the variable nature of waves, you will need AT LEAST 1000 waves with each fin type. You will need to compare the speeds using adequate statistical analysis, (pearsons and t-test should e adequate) to ensure that there is significant different in speeds, and that the data did not occur by chance.

The difference is immediately apparent on the first wave, and for your information I've had tens of thousands of waves on boards with and without tunnels.

Attempting to negate 13 years of in the waterv testing with a spurious jab like that is not going to get you anywhere.

YOU are the one who needs to do some practical testing !

You could also do a week of intensive testing in flow tunnels, with the forces at play carefully measured by instruments. Change the fin types and see how that changes the lift. The need for repeats is less apparent in a controlled environment, but try comparing fin size, location, shape.

Until you do the above, your "research" is worth very little indeed. 13 years is worth very little, especially as you did not state how much of that time was spent actually testing tunnel finned boards. There are research investigations that go on for 20 years or over with multiple people on a team that arrive at less definite conclusions.

What a load of crap.... my 13 years of testing means nothing but if the mainstream industry used the fin it would mean everything ... yeah right


You also assume that the value of my testing depends upon exactly what i do and don't say to youn personally.. . that's BS too.

Until you understand this and a few other points I won't be able to explain the more interesting aspects of tunnel fin behaviour.

Please do.

Then perhaps we can get into high and low pressure zones on the hull, and how the fin alters those.

After that, (if you are still speaking to me) the benefits of flex for boards with horizontal fin area and why they are greater than for flexible boards without horizontal fin area can be discussed.

A bit off topic, but the topic is yours, your call. I would be interested.

Off topic ? No it isn't.

You don't even have an entry level understanding of the topic, and are in no position to jusdge what is relevant.

It's also ludicrous to see that you pretend to be a champion of bernoulli's theory, and yet you claim that pressure considerations are irrelevant ! For your information bernoulli's theory is all about pressure.

It's aparent that you have already made up your mind on the basis that the surf industry doesn'yt use tunnel fins. Everything you trot out as a supposedly hydrodynamic objection to the tunnel fin has been completely wrong. this doesn't seem to bother you. I've seen this attitude before and it's always exhibited by those who make up their minds based solely on what the 'industry' does.

I can bring you to the water, but you must be willing to drink. At present your mind is closed and is protected by the most laughable of hydrodynamic myths.

I am a busy person but will keep discussing this subject with you, if and only if you first educate yourself regarding the fact that lift can be examined by bernoulli's and newton's theories and that does not mean that there are 'two kinds of lift'.

.

[Rickyroughneck]

That's pretty rich coming from someone who only a post ago thought that flat plates can't create lift.

Not if presented horizontally to the flow. If you believe that to be the case then you may benefit from some high school physics yourself. I should have been clearer first time around, but I stated "passing a plane underwater creates no lift".

.. which is false.
'
I can only respond to what you actually say.

What? Passing a flat plate through water at 0° to the direction of flow, (which is the scenario I was referring to), creates no upwards or downwards lift. If you think it does, then I point you to your comment:

Obviously ALL wings require an angle of attack in order to create lift. You need to understand that. It's elementary !

(Although this only applies to un-foiled wings, the essence of what you say is true).

Absolutely incorrect.

As stated previously a wing set up parallel to the bottom does produce lift. . . and plenty of it !

Your assumption that my tunnels are always set up parallel is also absolutely incorrect. Sometimes they are and sometimes they are not. In all cases they create lift.

If that is correct, then some of your tunnel fins may have produced some lift (although that still wouldn't mean they have a higher lift/drag ratio than the surfboard hull).

You are still adamant that parallel facing fins produce lift, so can you explain how the relative direction of water movement is directed towards the surfboard to provide such lift? Subscribe to a theory, until then, this discussion can go nowhere.

The two statements are consistent.. there is no contradiction.

You are mistakenly assuming ( again) that a wing which is set up parallel to the bottom has zero angle of attack.

In fact a wing set up parallel to the bottom has a positive angle of attack, particularly but not only in the case of enclosed annular wing systems which have infinite effective span.

I can explain why in detail if you wish.

Whether or not a wing is annular does not change the angle of attack. You may ALSO change the angle of attack, but a square shaped wing system and an annular system will have the same angle of attack if they are parallel to the hull.

Additionally, an "infinite wingspan" is used only in the context of having no wing tips. The fact that you have brought that statement out of context only proves your mistaken interpretation of the mechanics at play.

Please stop stating "I can explain in detail" unless you will actually follow through and do so. So far you have only stated bogus physics facts without stating how core mechanics enable said "facts". Please assume from now on that I would be interested in the full reasoning behind your theories. If I at least understand where you are coming from it may enable the correction of the underlying false principles on which you build your own rules.

Incorrect.

They are the same phenomenon explained in two different ways.

Please research the matter you will find that I am correct.

Until you do so the discussion will go nowhwere

It's also ludicrous to see that you pretend to be a champion of bernoulli's theory, and yet you claim that pressure considerations are irrelevant ! For your information bernoulli's theory is all about pressure.

Did you read what I wrote?

...in a sense, Bernoulli and Newton arrive at the same answer, (pressure). That said, pressure can explain all the physical forces in the world, it would be pedantic to drive that point beyond what you have done already.

Talking in real world terms now, Bernoulli's principle, and the Newtonian third are different methods of lift. Bernouilli's is the sucking lift, caused by reduction in pressure on the upper edge caused by water moving at increased speeds. Newtonian's third is the downwards force presented by a fin with an angle of attack. They are not the same. You can of course explain the other mechanic with the opposite theory (water moves slowly underneath providing a greater force, and the fast moving water has less contact force with the upper surface), but it is sloppy and unclear to do so.

This discussion goes nowhere because of your adamant refusal to admit that you are wrong despite overwhelming evidence. I do not blame you, as you are pushing a product, but you have to accept that that makes you no better than all the surfboard manufacturers who supply false claims to support their creations.

Perhaps. If they truly provided the advantages you claimed, then we would have seen them on the mass market years ago as "the next big thing". There is a lot of marketing in surfing, and a lot of barstardisation of design in favour of aesthetics. However if tunnel fins really presented such a huge advantage then shapers would have capitalised on that. The fact that they have barely been seen over all these years, and that modern tunnels are only fleetingly being touched on, suggest that the advantage presented is either non-existent, or marginal enough that the popularity isn't contagious.

bull to that !

I know what tunnels do, and the act that the mass market hasn't adopted tunnels does not in any way negate their value.

The argument you use is a logically fallacious one, do some research on logical fallacies in arument please.

Yes I know what fallacy is, but thankyou anyway. You should also know that most scientific experimentation is based on fallacy. You experiment, and if given conclusive evidence, you then assume that is the norm.

I've been attempting to explain to you what's going on but your undertanding is full of myths and misconceptions which I'm doing my best to clear up for you. Some of your sentences are ambiguous which makes them difficult to respond to.

You are not clearing anything up. In most cases you are saying "you are wrong" without offering an alternative. I am sorry if my sentences are ambiguous, I am trying my best to be clear (always imperative in scientific discussion). Please understand that the feeling is mutual. In a lot of cases I think we both could benefit from a clearer writing style.

By the way there's only one person who is 'all talk' in this conversation, and it isn't me.... I've been doing it with half pipe tunnel fins physically i.e. in the water testing for 13 years, as stated, whereas (unless I am mistaken ) you have not .

You are correct in that I haven't. But it is all too easy in science to arrive at the wrong conclusion (especially when you are looking for one) when your method of testing is imprecise, inaccurate and not easily repeatable.

Try actually recording your speed with two high res cameras positioned stationary on the beach to give you accurate bearings against time. Change ONLY the fin type (not the board) and repeat it enough times to build enough data for decent statistical analysis. At a rough estimate, given the variable nature of waves, you will need AT LEAST 1000 waves with each fin type. You will need to compare the speeds using adequate statistical analysis, (pearsons and t-test should e adequate) to ensure that there is significant different in speeds, and that the data did not occur by chance.

The difference is immediately apparent on the first wave, and for your information I've had tens of thousands of waves on boards with and without tunnels.

Attempting to negate 13 years of in the waterv testing with a spurious jab like that is not going to get you anywhere.

YOU are the one who needs to do some practical testing !

I am not the one trying to push hyper-expensive boards, two orders magnitude beyond their value and based on "hydrodynamic perfection".

Yes, your 13 years of "testing" is worth very little, and no it isn't just a "spurious jab". Your methodology is flawed. Ask anyone of value in the scientific community and they will tell you the same.

My question is this: If the difference is immediately apparent on the first wave then why, in 13 years, haven't you found any conclusive evidence?

You could also do a week of intensive testing in flow tunnels, with the forces at play carefully measured by instruments. Change the fin types and see how that changes the lift. The need for repeats is less apparent in a controlled environment, but try comparing fin size, location, shape.

Until you do the above, your "research" is worth very little indeed. 13 years is worth very little, especially as you did not state how much of that time was spent actually testing tunnel finned boards. There are research investigations that go on for 20 years or over with multiple people on a team that arrive at less definite conclusions.

What a load of crap.... my 13 years of testing means nothing but if the mainstream industry used the fin it would mean everything ... yeah right

Funny, I don't remember saying that. You are right though, if the mainstream industry used the fin it wouldn't change anything about the physical performance of tunnels.

That said, if the mainstream industry did use tunnels then the competition presented could drive innovative refinements to the foiling of tunnels, angling, shape, aspect ratio which would only be a good thing.

You also assume that the value of my testing depends upon exactly what i do and don't say to youn personally.. . that's BS too.

You can value your testing on the data collected and released. Link me to some conclusive evidence. No a shaky video by your wife doesn't count.

Until you understand this and a few other points I won't be able to explain the more interesting aspects of tunnel fin behaviour.

Please do.

Then perhaps we can get into high and low pressure zones on the hull, and how the fin alters those.

After that, (if you are still speaking to me) the benefits of flex for boards with horizontal fin area and why they are greater than for flexible boards without horizontal fin area can be discussed.

A bit off topic, but the topic is yours, your call. I would be interested.

Off topic ? No it isn't.[/quote]
Which is why I said it is your call.

You don't even have an entry level understanding of the topic, and are in no position to jusdge what is relevant.

You certainly don't have an exit level understanding granting your excessive preaching of "Roy theory". The real crime is that so many believe the "spurious nonsense" you produce to publicise your product. I understand this isn't the first time people have questioned your ideas.

It's aparent that you have already made up your mind on the basis that the surf industry doesn'yt use tunnel fins. Everything you trot out as a supposedly hydrodynamic objection to the tunnel fin has been completely wrong. this doesn't seem to bother you. I've seen this attitude before and it's always exhibited by those who make up their minds based solely on what the 'industry' does.

I made up my mind the moment your physics descended into the nonsensical. The industry has nothing to do with it, and there are examples of the tunnel fin in the industry, despite not "catching on".

Also, contrary to what you believe, the industry doesn't affect me beyond the subconscious level. I base my decisions and views on proof, and dislike false claims to forward a product. I base my purchases on price, shape and quality; as opposed to brand. I would rather surf an unbranded surfboard than one with "lost" written all over it, but if "lost" make good and well priced surfboards then I might buy one (I don't actually own "lost" anything, that is just an example).

You have a really pessimistic attitude towards other peoples opinions, which is quite sad in itself.

I can bring you to the water, but you must be willing to drink.

You are analogising yourself to Jesus? How crude and insulting.

At present your mind is closed and is protected by the most laughable of hydrodynamic myths.

My mind is open to proof. Provide me with proof and I will believe whatever theory you want me to think.

Your mind is closed however, I knew a person in my physics class back at school who reminded me of you, he HATED being wrong.

I am a busy person but will keep discussing this subject with you, if and only if you first educate yourself regarding the fact that lift can be examined by bernoulli's and newton's theories and that does not mean that there are 'two kinds of lift'.

Read my previous post.

Thankyou though, as patronising as your manner is, I do enjoy the "mental workout" ...so to speak.

[Roy Stewart]

What? Passing a flat plate through water at 0° to the direction of flow, (which is the scenario I was referring to), creates no upwards or downwards lift. If you think it does, then I point you to your comment:

You are confused.

I didn't say that it produces lift at zero angle of attack. You incorrectly assumed that a flat plate set up parallel to the bottom of the surfboard has zero angle of attack, which is incorrect.

You are still adamant that parallel facing fins produce lift, so can you explain how the relative direction of water movement is directed towards the surfboard to provide such lift?

Firstly the wing operates below the surfboard bottom where the flow is towards the surfboard hull at a greater angle than it is closer to or adjacent to the hull.

Secondly the hull sheds water outwards ( towardss the rails ), so the water flow is not parallel to the hull at all, it is always directed towards the hull.

Thirdly the tunnel fin ( as is true of all annular wings ) creates lift at very low angles of attack in comparison with the surfboard hull.

Whether or not a wing is annular does not change the angle of attack. You may ALSO change the angle of attack, but a square shaped wing system and an annular system will have the same angle of attack if they are parallel to the hull.

You missd the point, which was that enclosed systems produce lift at lower angles of attack than the surfboard hull does.

Additionally, an "infinite wingspan" is used only in the context of having no wing tips. The fact that you have brought that statement out of context only proves your mistaken interpretation of the mechanics at play.

That's incorrect. Tunnels are called 'annular wings' becuase they annul the tip.... they have no wing tips. Annular wings are treated as wings of infinite span because they enclose the flow and have no wing tips.

Please stop stating "I can explain in detail" unless you will actually follow through and do so. So far you have only stated bogus physics facts without stating how core mechanics enable said "facts". Please assume from now on that I would be interested in the full reasoning behind your theories. If I at least understand where you are coming from it may enable the correction of the underlying false principles on which you build your own rules.

I will follow through in more detail when we get beyond some of the basic myths which you are still subscribing to.

Doing some research would soon inform you that i'm correct in every respect.

This discussion goes nowhere because of your adamant refusal to admit that you are wrong despite overwhelming evidence. I do not blame you, as you are pushing a product, but you have to accept that that makes you no better than all the surfboard manufacturers who supply false claims to support their creations.

I'm right actually.

Lift can be calculated using bernoulli's theory or newton's theory, they are merely two methods of explaining the same phenomenon.

I suggest that you do some research on the matter.

It is ludicrous that you claim to be providing 'overwhelming evidence' when in fact you have provided no evidence at all.

It's a well known fact that bernoulli's theory and newtons theory give the same answer, and that they are not 'two different kinds of lift' but merely two explanations of te same phenomenon.

The myth which you are subscribing to is a common one and has been created by school teachers, it's well known that what i'm saying is true, please do some research so that you can learn the truth.

I am not the one trying to push hyper-expensive boards, two orders magnitude beyond their value and based on "hydrodynamic perfection".

That's really the crux of the matter in my opinion.

You are talking a lot of pseudo hydrodynamic nonsense based on old myths spread by high school 'physics' and your inability to make any headway in uderstanding is in my opinion due to the fact that you've made up your mind based on social issues quoted by yourself like 'too expensive' and 'not accepted by the mainstream surf industry'.

Clearly you know as little about the luxury goods market as you do about hydrodynamics.

I made up my mind the moment your physics descended into the nonsensical.

Excuse me but your so called 'physics' is demonstrably incorrect.

please do some research elsewhere, what I'm telling you is well known.

I can bring you to the water, but you must be willing to drink.

You are analogising yourself to Jesus? How crude and insulting.

It's not a quote from Jesus, it's a saying about a man and a horse.

I am comparing you with a horse.

At present your mind is closed and is protected by the most laughable of hydrodynamic myths.

My mind is open to proof. Provide me with proof and I will believe whatever theory you want me to think.

[/quote]


I won't get into the logical features of scepticism and how they apply to science.

Instead I suggest that you go and do some research on one of the main points which are preventing improvements in your understanding, i.e. bernoullian and newtonian treatment of lift.

If you can see your error on that simple point then we might be able to help you to make some headway in the understanding of tunnel fin physics.


.

[Roy Stewart]

By the way a wing which is flat on the bottom and curved on top does not produce lift at zero angle of attack.

This is true by definition of 'angle of attack'

Research it man !

[jaffa1949]

I would suggest that any readers of this post go to Roy's website and blogspot, there are Youtube videos of Roy surfing his boards there.
There is also a video elsewhere of one of the boards being used at Pipeline.
Look for yourself

[Rickyroughneck]

I would suggest that any readers of this post go to Roy's website and blogspot, there are Youtube videos of Roy surfing his boards there.
There is also a video elsewhere of one of the boards being used at Pipeline.
Look for yourself

Hello Jaffa!

I've seen a few videos on the olowhatsit site. Not really concluding the speed argument though.

They are big, heavy and gentle rockered (considering) so have the makings of a big wave gun! I would like to see the pipeline video, but didn't find it unfortunately.

[Rickyroughneck]

By the way a wing which is flat on the bottom and curved on top does not produce lift at zero angle of attack.

This is true by definition of 'angle of attack'

Research it man !

Yes it does. That is "Bernoulli's" theorem at play.

Research it man !

[Rickyroughneck]

Firstly the wing operates below the surfboard bottom where the flow is towards the surfboard hull at a greater angle than it is closer to or adjacent to the hull.

Secondly the hull sheds water outwards ( towardss the rails ), so the water flow is not parallel to the hull at all, it is always directed towards the hull.

Thirdly the tunnel fin ( as is true of all annular wings ) creates lift at very low angles of attack in comparison with the surfboard hull.

Okay, I can see where you are going wrong. You think that water is drawn up from below; however, anyone with a grasp of Newtons third can see that is completely incorrect. The water shed is the water displaced by the surfboard hull as it moves through the water, the water does not rise up, and the surfboard moves parallel to the water, not up or down.

So yes, the tunnel fin will need to be angled towards the surfboard to create a positive angle of attack, and thus any lift at all. How much so must be dictated by the surfboard's position in the water. If the rider is more centrally positioned, and there is exit rocker then the compensation angle will be greater, however if the exit rocker is flat and the rider is positioned near the rear, little compensatory angling will be required.

You missd the point, which was that enclosed systems produce lift at lower angles of attack than the surfboard hull does.

Null point, both the surfboard hull and enclosed systems will produce lift at any angle above parallel.

Additionally, an "infinite wingspan" is used only in the context of having no wing tips. The fact that you have brought that statement out of context only proves your mistaken interpretation of the mechanics at play.

That's incorrect. Tunnels are called 'annular wings' becuase they annul the tip.... they have no wing tips. Annular wings are treated as wings of infinite span because they enclose the flow and have no wing tips.

You say, "that's incorrect", then write a statement in complete agreement with me. Pick your battles man!

The first time around you used "infinite wingspan" in context with angle of attack, which is irrelevant, to refresh:

You are mistakenly assuming ( again) that a wing which is set up parallel to the bottom has zero angle of attack.

In fact a wing set up parallel to the bottom has a positive angle of attack, particularly but not only in the case of enclosed annular wing systems which have infinite effective span.

[/quote]
...unless you had suddenly moved onto wing tips without me knowing.

I will follow through in more detail when we get beyond some of the basic myths which you are still subscribing to.

Doing some research would soon inform you that i'm correct in every respect.

The more research I do, the more I am convinced that you are wrong. You have been "studying" these for years and have saturated your knowledge with nonsense. I had a basic understanding of the physics, but with every piece of research I do, the stronger my arguments become, especially compared to your weak and unsubstantiated arguments. That is not to say I will not make any mistakes, to assume one is "correct in every respect" is incredibly naive under any circumstance. Silly even.

I'm right actually.

How about this instead?

Lift can be calculated using bernoulli's theory or newton's theory, they are merely two methods of explaining the same phenomenon.

If the "same phenomenon" is lift, then yes, they both provide lift. Since lift is a force, and a force is supplied by pressure, then yes they both cause pressure differences. That is where the similarity ends.

One of the mechanics creates lift by the downwards displacement of water, the other produces it by increasing the speed of the water over the upper surface and can occur without any net water displacement.

I suggest that you do some research on the matter.

I did, I suggest you do the same.

The myth which you are subscribing to is a common one and has been created by school teachers, it's well known that what i'm saying is true, please do some research so that you can learn the truth.

You will not be happy unless I accept YOUR truth, which ironic because it is not truth at all. You build your principles on false grounds, ignoring basic principles such as Newtons third law.

School teachers can be right sometimes, although I do agree that often they present a simplified notion. I particularly notice this in biology.


That's really the crux of the matter in my opinion.

You are talking a lot of pseudo hydrodynamic nonsense based on old myths spread by high school 'physics' and your inability to make any headway in uderstanding is in my opinion due to the fact that you've made up your mind based on social issues quoted by yourself like 'too expensive' and 'not accepted by the mainstream surf industry'.

Try writing in shorter sentences, what you have written is borderline hard to understand. "Too expensive" is an absolute, I cannot purchase beyond my price range. I am relatively non-conformist though, I like being different to the other people. It is ridiculous for you to make personality assumptions on other people like that,

However, even if I was super rich, I would not buy one of your boards. There is little advantage to using wood over modern materials, I base my purchases on performance and practicality over looks and "luxury". Regardless of what you say, your boards are not the fastest, and they are definitely not practical. To clarify practicality, I mean weight and size. No way am I lugging a heavy 14 foot board anywhere. My limit is my 9'1 longboard... (heh "long" ).

Clearly you know as little about the luxury goods market as you do about hydrodynamics.

How many have you sold?

I made up my mind the moment your physics descended into the nonsensical.

Excuse me but your so called 'physics' is demonstrably incorrect.

please do some research elsewhere, what I'm telling you is well known.

Typical Roy Stuart:
"You are wrong"

"Do some research to find out why".


For your claim to actually hold water, you actually need to demonstrate that my physics is incorrect. Surprising eh, but that is how science works. Pasteur did not prove his critics wrong by saying "Do some research to find out why".

I can bring you to the water, but you must be willing to drink.

You are analogising yourself to Jesus? How crude and insulting.

It's not a quote from Jesus, it's a saying about a man and a horse.

I am comparing you with a horse.

How droll, I almost thought you were funny for a second. Oh wait, you have no social skills!

At present your mind is closed and is protected by the most laughable of hydrodynamic myths.

My mind is open to proof. Provide me with proof and I will believe whatever theory you want me to think.

I won't get into the logical features of scepticism and how they apply to science.

Okay.

Now for the essay:

Your tunnel fins will never produce lift to drag at a rate higher than the surfboard hull itself.

The optimum angle for lift-drag is about 5 degrees in aircraft wings, less in water since it is a denser medium.

The reason for this is friction, in a frictionless environment, with an infinitely thin "flat plate", the optimum angle for lift to drag is infinitely small. This is because there are diminishing returns in the lift generated as you angle the wing, however drag increases constantly (although I am unsure of the exact relationship of drag with regards to wing tilt).

To put into real world terms, the optimum 5 degrees comes from having to overcome the threshold of the friction of the wings surfaces and drag from the leading edge, while not being so great an angle as to increase drag more.

In surfing terms, the tunnel fin will not provide a higher lift to drag because with rider positioning, the surfboard hull can be positioned very flat against the water (indeed leaning forward to provide a flatter planing area is what gives control over speed to surfers). The tunnel fin cannot compete with the surfboard hull as long as the hull has a variable rocker with a flatter planing area in the middle, as the surfboard and thus the angle of attack) can be positioned as flat as the rider desires.

The unfoiled tunnel fin you provide will only increased friction and increased leading edge area.

The only way that a tunnel fin would be superior to current fins is if the advantages of eliminating the fin tip vortices outweigh the increased drag.

[Roy Stewart]

By the way a wing which is flat on the bottom and curved on top does not produce lift at zero angle of attack.

This is true by definition of 'angle of attack'

Research it man !

Yes it does. That is "Bernoulli's" theorem at play.

No, at zero angle of attack zero lift is produced.

The angle at which zero lift is produced is what defines angle of attack.

There is such an angle for every wing, including those which are foiled on top and flat underneath. Don't make the mistake of assuming that the angle of attack is parallel to the flat underside of the wing.

Once you have realised your mistake on this simple point I'll read the rest of your answers

[Roy Stewart]

Firstly the wing operates below the surfboard bottom where the flow is towards the surfboard hull at a greater angle than it is closer to or adjacent to the hull.

Secondly the hull sheds water outwards ( towardss the rails ), so the water flow is not parallel to the hull at all, it is always directed towards the hull.

Thirdly the tunnel fin ( as is true of all annular wings ) creates lift at very low angles of attack in comparison with the surfboard hull.

So yes, the tunnel fin will need to be angled towards the surfboard to create a positive angle of attack, and thus any lift at all.

That is absolute nonsense.

Tunnels produce lift when set up parallel to the surfboard hull.

If you were correct biplanes would not produce lift with the lower wing

You have so many fundamental hydrodynamic misconceptions that there's no hope of you understanding what really happens.

One of the mechanics creates lift by the downwards displacement of water, the other produces it by increasing the speed of the water over the upper surface and can occur without any net water displacement.

Wrong, it's a single phenomenon being explained using two different theories.

This is well known, you've been duped by high school physics.

The unfoiled tunnel fin you provide will only increased friction and increased leading edge area.

Unfoiled ?

You must be blind all my tunnel fins are foiled

Sorry mate you need to go back to school and start again.

.

[Roy Stewart]

One of the mechanics creates lift by the downwards displacement of water, the other produces it by increasing the speed of the water over the upper surface and can occur without any net water displacement.

By the way if there's no net water displacement there is no lift.

Such cases are defined as 'zero angle of attack' .

You are still subscribing to the naive high school myth in the application of Bernoulli's theory.

" there is an explanation based directly on Newton’s laws of motion and an explanation based on Bernoulli’s principle. Neither of these explanations is incorrect, but each appeals to a different audience. "


http://en.wikipedia.org/wiki/Lift_%28force%29#Newton.27s_laws:_lift_and_the_deflection_of_the_flow


"While the "Bernoulli vs Newton" debate continues, Eastlake's position is that they are really equivalent, just different approaches to the same physical phenonenon. NASA has a nice aerodynamics site at which these issues are discussed. "

http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

"According to Dr. Jean-Jacques Chattot, professor of Mechanical and Aeronautical Engineering and director of the Center for Computational Fluid Dynamics at the University of California-Davis, the descriptions of lift advocated by Newton and Bernoulli “are actually the same thing, just from two different perspectives.”

http://www.planeandpilotmag.com/component/zine/article/289.html

[billie_morini]

University of California - Davis (UC Davis): know it well. Was responsible for more than $8 Million of environmental remediation work there, have a house about 16 miles west of it (in Vacaville), and brought my dog to their superb vetinary college.

Sorry for being off-topic. Am enthused to see this familiar thing. While there is a little fishing in Putah Creek that runs through the South Campus, there is no surf at this hot, inland, Central Valley location.

[Roy Stewart]

Valley Girl ? ^^

[Rickyroughneck]

Sigh, I was quite enjoying the peace.

No, at zero angle of attack zero lift is produced.

The angle at which zero lift is produced is what defines angle of attack.

If that is your personal definition, then so be it, however in popular literature angle of attack defines the angle at which the surface "attacks" the flow. It is the comparison to the 0 degrees flow vector from which all wings can be compared. If you think about it, if angle of attack changes to accommodate each wing, then it no longer becomes a comparative measure.

http://en.wikipedia.org/wiki/Angle_of_attack

The minority view:
"Some books[2][3] adopt the so called absolute angle of attack: zero angle of attack corresponds to zero coefficient of lift."

That is absolute nonsense.

Tunnels produce lift when set up parallel to the surfboard hull.

If you were correct biplanes would not produce lift with the lower wing

Yes, but that is reliant on the very rear of the board moving at an angle befitting the generation of lift, beyond that of simple buoyancy.

Biplanes have their wings foiled and angled for lift, so of course the lower wing produces lift.

Unfoiled ?

You must be blind all my tunnel fins are foiled

Okay, although you did say earlier something along the lines of: some of my tunnel fins are foiled, others are not. They all produce lift.

One of the mechanics creates lift by the downwards displacement of water, the other produces it by increasing the speed of the water over the upper surface and can occur without any net water displacement.

By the way if there's no net water displacement there is no lift.

Of course. I realised my mistake reading through it, but couldn't be bothered to rephrase since it would involve more blabbing on a topic that has already been discussed to death.


With regards to Bernoulli's vs Newtons third:

Thanks for the examples, I did state earlier the overlap between the theories, and how all physics boils down to the "same set of rules", i.e. they both create lift by the downwards displacement of water. The difference is that the downwards displacement is facilitated through different means. To argue any further is as futile as arguing over "what came first: chicken or the egg", without the easy cop-out solution that eggs were used long before even the earliest birds evolved. For the sake of argument, lets agree to disagree.

I agree with the worldwide consensus in that the two are different, not least because they are engineered for independently and are spatially discreet (unless you want downwards sucking wings).



My question is this:

Have you not got better things to do with your time?

[jaffa1949]

Roy's fiftieth birthday is coming up, there still isn't enough candles yet to provide the wax his boards need. Have a happy birthday Roy.

[Rickyroughneck]

Happy Birthday Roy!

[surf patrol]

Happy Birthday!

[Z mann R2]

How can you be so asinine to charge that much for a board? Who in their right mind would spend that much?? If they do they aren'y gonna even be a surfer. Just a show off with mooney