Yesterday morning, I was watching the ESPN In The Classroom program about drag. Amanda Beard was the athelete guest host. It didn't mention anything about lift. It talked about the effects that the new suits are having on reducing drag. I am very confused, partially because that is my life, about reducing drag while swimming. It seems to me that if you reduce drag too much, you're going to reduce lift also.
Lift and drag are opposite forces that form an "L". Which of the three forms of drag are reduced by the new suits, and which of the three do you want to remain to promote forward movement? The product of lift and drag is the foward movement from the center of the "L". That force is what moves you forward. Or so I thought.
The program did talk about high and low pressures. I understand that in front of you there is a high pressure and a low pressure behind. that nature prefers low pressure and that there is a struggle to move through the high pressure. The program also mentioned near the end about hydroplanning. If I understand correctly, that's how Johnny-Tarzan swam.
Can anyone explain this to me in terms that I can understand. Please keep in mind that I was an anthropology major at a very liberal Liberal Arts college.
Former Member
I guess some company could make a swimming suite with something like little hair in the inside part of the arms that could attach to the suite when dragging (streaching your arms over your head) and do the opposite when lifting (pulling) as they are also opposite kind of movement.
If you are swimming from left to right in this page, the hair in the suite that I am mentioning would look like this when pulling:
\\\\\\\\\\\\\\\\\\
and like this when dragging:
_____________
:rolleyes:
Was I able to explain my idea clearly?
What do you people think about it?.
Craig,
I agree with Knelson. Drag is the friction your body creates as it moves through a liquid. I have heard the term lift used to describe the effect on an airplane wing created by the difference in pressure above and below that wing. Please note that a wing does not make a plane go faster; it simply lifts (there's that word again) the plane off of the ground. As Knelson observes, perpendicular to direction the plane is moving.
However, we swimmers do make use of friction at certain key points of our bodies (e.g. our hands and forearms) to move through the water. If we had no friction, we'd simply flail around in the water unable to move. (Rather like astronauts in a weightless environment who get stranded without being able to push off on any solid surface. The resistance of a hand or foot pushing on air is too weak to generate much momentum.) So the key thing for swimming is how do we minimize friction that becomes drag, while still allowing us to use friction (on our hands, foreams and feet) to propell ourselves forward?
The answer is that depends. Your lower legs are a case in point. For freestyle and backstroke the thinking is that your legs from the knees to the ankles create more drag than they contribute as a useful surface for propelling yourself. Thus you tend to see freestylers and backstrokers wearing the drag reduction swimsuits that go down to their ankles. In contrast, most top level *** strokers will tell you that they are using their lower legs from their knees on down to push off in their kick (and *** stroke is far more kick focused than the other 3 strokes). Thus, you will not see many of those swimmers covering their lower legs.
Next question is whether these drag reduction suits help, and if so to any significant degree? The manufacturers have their flume studies, but people are wisely skeptical of accepting whether a scientifically measurable effect will translate to any meaningful effect on their swimming. I happen to be fortunate enough to have stumbled on my own functional study. One year at Nationals I had a teammate roughly the same size as I am who brought an extra drag reduction suit (shoulders to knees). I swam a couple of events in my normal speedo brief. Then Andy offered to let me try his old suit on. During warm-ups I noticed right away my stroke count per 50 meters was down about 2 or 3 from what it had been earlier with my normal suit. This convinced me the effect is real for my body and at my level of conditioning. Also, being an older suit, it developed an interesting tear in the middle of one of my events, which Tall Paul has found so amusing and noteworthy the past FIVE YEARS (for the love of Pete) since the meet. Try your own experiments and see what works for you.
There are a couple of other theories of drag reduction out there. Hydroplaning being one that is pretty much considered dead. Yes, it may work for powerboats or flipper, but people can't swim nearly fast enough to cause the hydroplane effect. Consequently, when you try to do so, by lifting your head higher on the water (by putting the waterline on your hairline or, egad, your eyebrows as some coaches advised), all you do is cause your legs to sink deeper, with a net increase in drag.
Another theory is front quadrant swimming; some folks find that controversial. Emmett Hines and Total Immersion-istas have written extensively on this theory. It starts with the flume studies that indicate all other factors being equal, a longer vessel suffers less drag moving through the water than a shorter vessel. This leads to the theory a swimmer should delay his pull long enough to get the recovering arm as far forward as his ear. Thus, one or both arms are in the water and forward of the shoulders at all times, and the swimmer swims "taller" by "lengthening his vessel" (to use two TI buzz phrases). On this web site, in the Training-Articles section, you can read a piece by Emmett titled "Of Gravity and Air" that discusses this theory. Critics of front quandrant swimming argue that swimming catch-up style freestyle is not the same thing as a boat that is longer all the time. Their contention is that if you get any reduction in drag at all, you lose more by delaying your propulsive backward push. The evidence they cite is that Japanese swimmers made popular catch-up freestyle with their successes in the 1950s Olympics, but U.S. swimming subsequently discovered it to be a dead-end theory. Whose right? Everyone is entitled to their opinion, and we all get to live with the results we achieve following our preferred theory.
The underlying theme is that drag is a force to be reduced whenever possible. It is why no one seriously advocates "Superman" turns (head up, arms extended wide), or the weak swimmers' technique of swimming with your head, neck and as much of your torso as possible out of the water at all times. When your streamlining technique begins to involve tradeoffs, that is where the testing and debating begins.
Matt
There is a great article in a recent ASCA magazine about lift and drag which basically says our current level of technology does not let us determine how much each contributes to propulsion. As to hydroplaning, it is relatively unimportant in swimming. It's effect is trivial in swimming but not zero if you are exceding your bow speed. The concept of bow speed is why taller swimmers have an advantage. I beleive the formula is S=1.34Xthe square root of L where S is speed in knots and L is length in feet. When the speed is faster than this the vessel(swimmer) is climbing on it's bow wave and is beginning to hydroplane. I notice when sprinting free I feel a slight rise in the water. Arching the back won't increase this effect,but will increase your frontal resistance and probably slow you below your bow speed anyway. If you Google bow speed you can find a conversoin table and then enter your height to find your bow speed.
Originally posted by craiglll@yahoo.com
The program also mentioned near the end about hydroplanning. If I understand correctly, that's how Johnny-Tarzan swam.
From what I've read, there is no way on earth that you can reach the necessary speeds (under your own power) to hydroplane.
If you can float in the water without swimming, then I wouldn't worry about the lift component when swimming. (You may be thinking about lift vs. drag, as it applies to the hand/arm pull.)
Our bodies don't create significant lift while swimming and there's no reason to want them to. You're wrong about lift and drag being opposite forces. As you said they form an L, i.e. drag is a force opposing forward motion while lift is a force perpendicular to this. Reducing form drag is what these high tech suits strive for.
In the simplest terms we use our arms and legs to produce thrust (this is the force opposite to drag). We want to do this as efficiently as possible so we can produce the maximum thrust while producing as little drag as possible.
The forces are only equal if we are not accelerating. This is what we call "static equilibrium." In swimming things are very dynamic. During the propulsive part of the stroke we ARE accelerating, then there is a portion of the stroke cycle where we are decelerating due to drag.
Talking about how drag is actually important for propulsion just complicates this particular discussion. Good streamlining, shaving the body, or high tech suits all work to reduce drag and that's all we're concerned with.
Which part of this do you think is contrary to physics?
Originally posted by knelson
Our bodies don't create significant lift while swimming and there's no reason to want them to. You're wrong about lift and drag being opposite forces. As you said they form an L, i.e. drag is a force opposing forward motion while lift is a force perpendicular to this. Reducing form drag is what these high tech suits strive for.
In the simplest terms we use our arms and legs to produce thrust (this is the force opposite to drag). We want to do this as efficiently as possible so we can produce the maximum thrust while producing as little drag as possible.
Opposite and equal. I thought that thrust was the force that begins at the center of the "L". Is it possible to really reduce drag as we are increasing thrust. Is it that we want to produce more of one type of the three drags (Yes I'm laughing at the thought of drag queens at a swim meet.)?
It seems to me that in ways we are saying that swimming is a special event that denies physics.
