Rickyroughneck wrote: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.
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 .