Swim smarts: Engineers? Drag increases as speed increases?
Former Member
I overheard one of the local club team coaches prepping the kids before a technique based drill make the statement that the faster you go the more drag you encounter. He was having them ensure they kept their shoulder to cheek on their free sets to narrow the frontal profile. While I am not questioning the coach I just wanted to know if one of you smart Masters swimmers might be able to dumb that down for me.
So to ensure I lay this out to the best of my understanding which is probably wrong: for two physical clones swimming freestyle in lanes next to each other with completely identical technical strokes down to the mm. The drag for the 1:20 pace swimmer will be less than the swimmer peeling off 1:10 splits? I'm a big dummy so wrapping my head around that idea just isn't sinking in.
Thanks for the Saturday morning hydrodynamics lesson!
I wonder if a near maximum velocity exist for surface swimming, where going any faster wouldn't be possible, any remaining room for improvement is in starts, reaction, and underwater streamline, and how close current records are to it.
Humans are not very good boats,but apply enough force and the human form will plane(think being towed by a boat or body surfing a relatively large wave.) When planing form drag decreases greatly,but I don't know what happens to wave drag.Anyway,I doubt there is a firm limit as to how fast a person can swim.
The amount of drag increases with the square of the velocity (see Swimosaur above).
The power required to push a static shape underwater with no wave interaction increases wit the cube of the speed yes.
However, last time I looked at something like this when looking at active drag of actual swimmers, the drag increased with speed raised to the 2.4th power in the study. I have seen one or two others, it varies by measurement method but the drag never goes up with the square of the speed.
As swimmers we are on the surface and have to deal not only with form drag but also wave drag, we are also constantly changing shape and length of our vessel as we swim making the whole thing not amenable to the simple equations we engineers like to use.
As long as we are discussing the outer limits, I wonder if it's possible for a human to power some sort of hydrofoil based on swimming. There's this: www.human-powered-hydrofoils.com/ but the images all show bike/kayak/jet ski contraptions. I wonder about some sort of tech suit with a hydrofoil...
Former Member
Thanks for all the input folks this is great. I was fiddling around with what I overheard from the club coach and darned if it wasn't immediately noticeable when I kept my shoulder to cheek. I had unknowingly been allowing a big gap between there simply b/c I didn't know it mattered. What I felt was just easier momentum, less surgey, which I took as less resistance allowing me to keep my speed up a bit better. Thanks again for dumbing it down for me:)
Would a tech suit with a hydrofoil be something like a "fish suit?" Has anyone tried creating something like that? I'm picturing a rigid, bullet-shaped suit with a large mono fin out the back and large flippers on the side for the arms. I was watching seals at an aquarium recently and it seemed that with the slightest movement of their side flippers, they'd shoot off with amazing speed.
Maybe I'm in lala land, but it would be cool!
Would a tech suit with a hydrofoil be something like a "fish suit?"
Not quite. Think of replacing the human+kayak+hydrofoil bits in this picture:
www.human-powered-hydrofoils.com/.../7059a2bd5d79d861d4d666b6154f546d_f105.jpg
with human+weird tech suit+hydrofoil bits. The human effectively becomes the kayak hull. Swim fast enough (I'm really waving my hands here!) and you rise up on the hydrofoil. It seems to me that the tech suit would have to be very stiff (otherwise the hydrofoil would flop around), and once you're up and out of the water, you could really only propel yourself with your arms.
I know, it's almost certainly a bad idea, but, hey, I didn't get much sleep last night and the bike ride home today was in 95+ degree weather... What do you expect?
Ha ha - I woke up this morning wondering "What the heck was I thinking?" about my idea too, and also came to the conclusion I must've been suffering from sleep deprivation. My fish suit would only work underwater for one thing - hence some kind of "human powered submersible" or maybe just a glorified scuba suit - a kind of mash up of I-Am-The-Walrus-In-A-Yellow-Submarine, I guess.
But if a person could actually get up enough speed to rise up on your hydrofoil, I imagine they'd have such low resistance at that point that they could keep going with much less effort? Maybe they'd just need extra-large paddles on their hands?
Crazy as these ideas sound, you just never know. I had actually pictured this as a kid:
en.wikipedia.org/.../Zorbing
and now it exists.
Still, better hand these things over to the engineers and let them figure out the details...
As swimmers we are on the surface and have to deal not only with form drag but also wave drag, we are also constantly changing shape and length of our vessel as we swim making the whole thing not amenable to the simple equations we engineers like to use.
This. :agree:
