Physics and the racing start.

When I ask coaches why the start should be straight out instead of angled up I never get an answer other than it has been found to be faster. Maybe the absolute speed off the blocks pales in comparison with the increase in drag experienced when you enter the water, so that it's more important to enter cleanly than to get absolutely as far as you can in the air (and risk a significantly "less clean" entry). I'm sure I'm not explaining myself very well, but the time to 15m has to equal the time to entry plus the time after entry to 15m. A poor entry may cost you more time after the entry than you gain before the entry, even if you go further before entry.

Maybe the absolute speed off the blocks pales in comparison with the increase in drag experienced when you enter the water, so that it's more important to enter cleanly than to get absolutely as far as you can in the air (and risk a significantly "less clean" entry). I'm sure I'm not explaining myself very well, but the time to 15m has to equal the time to entry plus the time after entry to 15m. A poor entry may cost you more time after the entry than you gain before the entry, even if you go further before entry. I absolutely agree,but If you go off the block at an upward angle,you will can more easily control your angle of entry.The natural tendency will be to enter at a steeper angle making it easier to go "through the key hole."A case can be made that you are then too deep,but if you are swimming BR or use significant SDKs it is an advantage to go deep.My hypothesis is that the flatter start gets you off the block faster so people who are wowed by that love it and that it is probably faster for people with relatively greater upper body strength over leg strength who get significant thrust from the sling shot.That describes many sprint freestylers and in sprint free a shallower entry can also be an advantage.So this start may be the best for many sprint freestylers(again I am waiting for some science about this) and since those are the people that we think we should emulate people are not necessarily using the best start for them.

I believe the most important aspect of the start is an efficient transfer of the energy you get as your 180lb body falls down about 3 feet from the block into the water. You must transfer that energy from a downward direction to a foward direction under the water. When you dive off the blocks your foward speed remains roughly constant but you downward speed increases the further you fall. It is that downward speed that can be transferred to foward speed by a clean entry at the right angle as you hit the water and as you level out. So it is a combination of reaction time foward speed off the block and skill in entry technique, leveling out,SDK and breaking out. And, it is about 15 meters of every race.

One thing about those take off angles is those formulas are assuming the object is a point (dimensionless). The human body has a significant size compared to the total distance traveled. In a horizontal dive the legs/feet might still be moving up at 30-35 degrees but the head and torso might be moving straight out. You can kind of see that in this video along with an excellent entry: www.youtube.com/watch

I believe the most important aspect of the start is an efficient transfer of the energy you get as your 180lb body falls down about 3 feet from the block into the water. You must transfer that energy from a downward direction to a foward direction under the water. When you dive off the blocks your foward speed remains roughly constant but you downward speed increases the further you fall. It is that downward speed that can be transferred to foward speed by a clean entry at the right angle as you hit the water and as you level out. So it is a combination of reaction time foward speed off the block and skill in entry technique, leveling out,SDK and breaking out. And, it is about 15 meters of every race. Yes,but if you angle up you are falling from a greater height,perhaps 4 1/2 or even 5 feet instead of 3 with ,therefor much greater velocity to be transferred.

Once in the water in dives 2 and 3, the swimmer's body is like the wing of a airplane and the entry velocity produces lift forces that push the body both horizontally forward (and upward). Going through the key hole at the proper attack angle minimizes entry losses, maximizes entry velocity, and produces the most lift force. I'd argue this. You're not going to create lift with a negative angle of attack (i.e. your hands are lower than your legs). In fact any hydrodynamic forces created will be oriented toward the bottom of the pool. I'd also argue that you probably don't want to create lift. All that's going to do is cork you up toward the surface. If you're a good underwater kicker you might want to stay under longer.

This is an interesting question that i've wondered about too, especially observing the changes in starts over the years. From what i've watched the possibilities are: Old school - dive straight out and land flat skimmming across the surface like a stone (or just under the water surface). This "belly flop" start is what i and most swimmers learned in the 50s, 60s and early 70s. No pikes and just flutter uw. Basically, push straight out to maximize horizontal velocity flying through the air, head up and thus maximize horizontal velocity going down the pool when you hit the water in a skim. This makes sense if humans were very streamlined and could enter the water nearly flat without a lot of energy and velocity loss (like a torpedo). But we can't. Newer school - dive somewhat upward to acheive additional height, then pike (or whatever) at the apex, and then drop and enter the water at the best angle of attack to conserve momentum at entry. Basically you use the momentum from the start to gain elevation (potential energy) and drop through the "key hole" into the water at the right angle to elliminate the entry losses and sustain momentum. If you watch the Lundquist '84 start that Allen posted (you can't see Lundquist at the start, but watch the first two swimmers) and pause the video at the apex. They are higher and have used some of the kinetic energy from pushing off the block to maximize and gain height and potential energy at the apex. This potential energy then transfers back to kinetic energy at entry and the ideal angle of attack at entry conserves the forward momentum. The starting energy being used to gain height is i think used to get deeper, faster, at entry. This dive seems to maximize elevation and "hang time" in the air. Some horizontal velocity is retained from the starting push but not as much as from the straight horizontal dive in 1 above. The most absurd case of this would be to dive almost straight up in the air maybe (like a diver on a springboard), pike, and try to enter the water at the best angle of attack. We know this won't work. More recent school - it's seems to me that swimmers are actually diving a bit downward when driving off the block. Maybe its an illusion (just gravity and they are not acutally diving slightly diving downward), but it seems to me they've eliminated the aforementioned "hang time" and my thinking is in an effort to get into the water faster (also lowered head between ears keeps goggles on). The instant the feet leave the block, the horizontal velocity in the air continually slows until the swimmer gets in the water. One may at first be flying through the air faster than in the water, but probably not for very long. Once in the water in dives 2 and 3, the swimmer's body is like the wing of a airplane and the entry velocity produces lift forces that push the body both horizontally forward (and upward). Going through the key hole at the proper attack angle minimizes entry losses, maximizes entry velocity, and produces the most lift force. AND, the swimmer can start to kick (sdk) or pull br when V drops low from drag. I don't know if i remember enough physics (or ever knew enough) to write out the equations for each of these conditions and i suspect that even if i could, it would be difficult to calcualte the time to reach 15m with any accuracy for comparison of each of the three dive cases. As Allen pointed out too, sprint starts involve a different strategy. In either case, trial and error (empirical) experimentation probably will produce better comparisons than formula calculations. This is just my thinking/observations on what is going on; i may be missing something and it's fine to be critical.

The "new" dives are indeed going down from the very start. That is because they are all using the track start and there is no easy way to make any initial vertical movement when your front foot becomes a fulcrum about which your body rotates as it is being pushed by the rear foot. Fast entry is the big sales point in the track start, and it works very well. Now that we use good streamline and SDK, the extra drag induced by a short dive is overcome (or maybe reversed in some cases) by technique. I still use two feet at the front of the block with a partial vertical jump and clean entry. The velocity of my entry has usually created enough momentum that even though I am last in the water, I often break out ahead of the heat (I use the SDK, too). The only drawback is that it is a pretty deep dive, so shallow pools create a problem. Solution: I just swim backstroke in those pools now.

I get it now (I think). The apex will always be symmetrical. If you start about 1m higher up (block) on one side, the only way to achieve an apex maintaining optimal angle of entry is to enter the water over 7+ meters out, if your superman. You must also have momentum to keep your attempted body angle/entry angle goal moving forward so entering just several meters out using the trailing end of the apex seems to be the ideal approach. That's what the new blocks signify, and it seems to be quicker too. From Dr. Frog's post: upload.wikimedia.org/.../512px-Ideal_projectile_motion_for_different_angles.svg.png Happy Thanksgiving

I'd argue this. You're not going to create lift with a negative angle of attack (i.e. your hands are lower than your legs). In fact any hydrodynamic forces created will be oriented toward the bottom of the pool. I'd also argue that you probably don't want to create lift. All that's going to do is cork you up toward the surface. If you're a good underwater kicker you might want to stay under longer. I'm thinking the body at entry from a dive is similar to your arm entering fingers first with high elbow producing llift forces acting perpendicular to your arm (although I've never believed the lift forces acting on your arm are significant - the catch and newtonian reaction force being more significant). However, because your body is a much bigger wing, could the perpendicular lift force on the body be significant at entry from a dive? At entry, components of the force would be upward and forward until you level out underwater at which point they would be upward (along with bouyant forces). Once ascending to the surface the lift forces on the body would be acting perpendicular to your body and seemingly upward and backward, definitely not good. The drag forces underwater are considerably more substantial than those acting on the airborne body leaving the block. Regardless, in case 2 the swimmer travels further in the air but spends more time in the air. In case 3 (as Roland Schoeman describes) the swimmer is getting into the water faster at a shorter distance with more energy transfer down the pool underwater. Can the swimmer in case 3 reach the same point where the case 2 swimmmer entered water in less time? I think so.