victorzamora
Contributor
You're clearly trolling. Please stop. The amount of misinformation being put out is insufferable.
steel 120's for side mount?
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djcheburashka
Contributor
Not really... Let's hold things constant sticking with two tanks for each diver. On the bm diver half (or so) of the tanks' surface area is covered by the wing, which wraps around.
There's also that cutting the water thing...
---------- Post added August 26th, 2014 at 01:10 PM ----------
Victor: right back atcha
There's also that cutting the water thing...
---------- Post added August 26th, 2014 at 01:10 PM ----------
Victor: right back atcha
I think all of this is not considering the special properties of water enough on both sides.
One of my favorite moves to practice is 'airbreaking' (most fun when dropping off to a side when being second on a scooter): Just opening the fins and gliding to an exact position with small twists of the ankles.
Does not disturb the water at all.
When used to go towards a big vertical wall, however, most times one has to compensate for the currents induced in the surrounding water just by the body replacing the water where you are, most times that will drag back against the direction you came from.
Those effects seem much more pronounced to me when going even only a little bit faster than fin-speed on a scooter.
You not only feel the water moving towards you in front, you also feel the water resisting separating from you in the back (figuratively speaking).
You always have drag in the water and it will move on its own if you go to slow to feel that.
Perhaps you will not understand the explanation (without being very open minded about it at least), it is hard for me to explain even without translating.
---------- Post added August 26th, 2014 at 08:53 PM ----------
It is not covered that tightly, that will not be enough. Instead it would flap in the current.
Considering your own Avatar picture for example I see the wing increasing the surface area significantly and not covering much of the tanks doing that.
The valves that are protected from current in sidemount are completely exposed and will induce turbulence that hit the tanks a moment later dragging and pushing.
You could discus this for years and even do measurements (that will always be biased by the preconceptions of the one doing them), proving anything you desire.
The only way to do this is to see the obvious.
You may be right in special circumstances, you cannot be right in all, that could easily be proven in a pool in an afternoon.
Rant following
:
Why do divers always get into fights about everything on the internet?
Beginning divers always think this to be different in reality.
Experienced divers seem to have to outdo each other everywhere they detect someone doing something 'differently' (even if they know its a bad way of doing it).
We all need to stop that! Everywhere!
I got into taking about computer games a few times in the last year.
They do not work for me anymore.
Reality has become so much more satisfying than Wing Commander ever was.
I just want to have the most fun I could ever have imagined (and like to share it) and it is always spoiled by people thinking they have to get ugly to prove their experience or to show their special worth as instructors.
Even Steve himself only claims to have 15 years of sidemount experience.
We are all beginners!
but nobody is very far from that, or does anyone think he would not continue for that amount of time?
There are exceptions from that of course, having known about it for decades, but, come on, before Steve nobody knew sidemount was anything to go crazy about.
One of my favorite moves to practice is 'airbreaking' (most fun when dropping off to a side when being second on a scooter): Just opening the fins and gliding to an exact position with small twists of the ankles.
Does not disturb the water at all.
When used to go towards a big vertical wall, however, most times one has to compensate for the currents induced in the surrounding water just by the body replacing the water where you are, most times that will drag back against the direction you came from.
Those effects seem much more pronounced to me when going even only a little bit faster than fin-speed on a scooter.
You not only feel the water moving towards you in front, you also feel the water resisting separating from you in the back (figuratively speaking).
You always have drag in the water and it will move on its own if you go to slow to feel that.
Perhaps you will not understand the explanation (without being very open minded about it at least), it is hard for me to explain even without translating.
---------- Post added August 26th, 2014 at 08:53 PM ----------
I think you are grabbing at straws there, do you really scooter only with a full wing?
It is not covered that tightly, that will not be enough. Instead it would flap in the current.
Considering your own Avatar picture for example I see the wing increasing the surface area significantly and not covering much of the tanks doing that.
The valves that are protected from current in sidemount are completely exposed and will induce turbulence that hit the tanks a moment later dragging and pushing.
You could discus this for years and even do measurements (that will always be biased by the preconceptions of the one doing them), proving anything you desire.
The only way to do this is to see the obvious.
You may be right in special circumstances, you cannot be right in all, that could easily be proven in a pool in an afternoon.
Do I still get my chance to defend Atlantis?
Rant following
: Why do divers always get into fights about everything on the internet?
Beginning divers always think this to be different in reality.
Experienced divers seem to have to outdo each other everywhere they detect someone doing something 'differently' (even if they know its a bad way of doing it).
We all need to stop that! Everywhere!
I got into taking about computer games a few times in the last year.
They do not work for me anymore.
Reality has become so much more satisfying than Wing Commander ever was.
I just want to have the most fun I could ever have imagined (and like to share it) and it is always spoiled by people thinking they have to get ugly to prove their experience or to show their special worth as instructors.
Even Steve himself only claims to have 15 years of sidemount experience.
We are all beginners!
but nobody is very far from that, or does anyone think he would not continue for that amount of time?
There are exceptions from that of course, having known about it for decades, but, come on, before Steve nobody knew sidemount was anything to go crazy about.
Last edited:
djcheburashka
Contributor
I don't have a full wing scootering, obviously, but since the scootering will take place not at the very end of the dive, there will be some gas in it yeah.
My profile pic is from like 5 years ago... It was also taken in fresh water, and I think those are hp 119s on my back (just the thought makes me ache...)
The wing won't flap unless it's completely empty.
None of us really get this fluid dynamics thing, but it seems to me that that sm tanks will create more drag simply because they're free to move a bit, which they do. Since the only energy is what you're putting in to move forward, that bouncing around is energy that you want to go in one direction instead being diverted to another.
My profile pic is from like 5 years ago... It was also taken in fresh water, and I think those are hp 119s on my back (just the thought makes me ache...)
The wing won't flap unless it's completely empty.
None of us really get this fluid dynamics thing, but it seems to me that that sm tanks will create more drag simply because they're free to move a bit, which they do. Since the only energy is what you're putting in to move forward, that bouncing around is energy that you want to go in one direction instead being diverted to another.
You are absolutely right there.
That's why it is desirable for maximum performance to have the tanks as close to you as possible.
In other situations drag can be used for a benefit, when trying to stay stationary without effort for example.
From my perspective we try to get to less surface area and that positioned as streamlined in the water as possible (and call that 'trim' and 'streamlining').
That can be very successful compared to a restrictive backmount setup, it isn't always. We could always find good examples for both points of view.
But you have to admit:
The average diver using a powerful scooter with a similar system for backmount and sidemount with two identical tanks backmounted once and sidemounted another time would prefer sidemount afterwards - because he was faster, more maneuverable and had a longer reach before exhausting the batteries.
That's why it is desirable for maximum performance to have the tanks as close to you as possible.
In other situations drag can be used for a benefit, when trying to stay stationary without effort for example.
From my perspective we try to get to less surface area and that positioned as streamlined in the water as possible (and call that 'trim' and 'streamlining').
That can be very successful compared to a restrictive backmount setup, it isn't always. We could always find good examples for both points of view.
But you have to admit:
The average diver using a powerful scooter with a similar system for backmount and sidemount with two identical tanks backmounted once and sidemounted another time would prefer sidemount afterwards - because he was faster, more maneuverable and had a longer reach before exhausting the batteries.
victorzamora
Contributor
Speak for yourself. There are those of us that are degreed Aerospace Engineers with a specialty in Fluid Dynamics.
djcheburashka
Contributor
Actually I meant you in particular-I looked up what a Reynolds number is, and you were totally talking out your rear
victorzamora
Contributor
First of all, there's not "a reynolds number." It's a concept, not a number. Seconldy, what makes you think I'm wrong? It's the ratio of viscous to inertial forces and is used to predict flow patterns in different fluid conditions. Water vs air is a different fluid condition. Different speed is a different fluid condition. Reynolds numbers are what need to match to up-scale or down-scale things, and is a great predictive tool.
I'm glad that you think thirty seconds of google-fu is worth more than my degree.....but you're certainly alone in that thought.
djcheburashka
Contributor
Do I think you're wrong about what a Reynolds number is? I think it doesn't have a thing in the world to do with anything we were discussing. We aren't trying to scale anything up or down. Razorista was asking if the concept of cutting the water, which you said only applied at supersonic speeds, might actually apply underwater. You said no, because water and air behave the same at the same Reynolds number. It's technical lingo deployed to no legitimate purpose.
---------- Post added August 26th, 2014 at 02:44 PM ----------
I am still totally amazed that a discussion about scuba diving configurations as somehow become a debate about a fluid dynamics of supersonic aircraft.
---------- Post added August 26th, 2014 at 02:44 PM ----------
I am still totally amazed that a discussion about scuba diving configurations as somehow become a debate about a fluid dynamics of supersonic aircraft.
victorzamora
Contributor
Razorista asked about supersonic airflow acting more like a liquid than a gas. I said that no, at similar Re values they should act similarly. It had nothing to do with the "cutting water" debate. I said the "cone" thing you mentioned was only valid at supersonic speeds, which it is. They were two totally separate things.
I'm right about what Reynolds number refers to, and I was right to use it. He had a question about fluid dynamics, which I answered.
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