Flying Underwater, A Blast From The Past

[REVAN]

Also just a query on your statement that undulating has drag advantages, to my knowledge the fastest and most efficient swimmers are the thunniform group , this group is characterised by minimal body pitching, with the tail fin being the only part that moves substantially.

Take a look at this training video:

I'm the one using the DOL-Fin hydrofoil fin. Notice how my technique using a monofin core undulation with minimal knee bend produces a thunniform swimming style. In contract, the diver with the hyperfin has a technique more like Goran Colak's with a significant amount of knee bend, which results in a swimming style closer to subcarangiform, or carangiform motion.

The difference between the squat motion and a kick motion is that in the squatting technique over the stoke you barely break perfect form , drag wise.... With your fin the dolfin unlike other standard monofins I believe you can use a technique that has a similar drag profile to that of a the squatting motion, but I believe you can only do it by putting in less power, for freediving purposes this probably doesn't matter as you don't put in full power, but for other types of swimming where putting in max effort for max speed is prefered it does.

This is how I see it:

Core Undulation = Thunniform style with minimal drag

Squating Motion = carangifirm (similar to thunniform core undulation but with breaks in streamlining at the butt, and at the knee bend).

Knee dominated kick = subcarangiform (more movement at the front and large break in streamlining at the knee bend).

Freediving is best with core undulation. Scuba diving works best with the squating motion because the tank restricts spinal movement and creates a wake that counteracts any benefits of the thunniform motion. The power input is related to the speed and frequency of the fin stroke, not the amplitude. The amplitude should be held relatively constant, regardless of the power input.

 

[tampabay scott]

I haven't made any progress with my project yet. I made a lamination for the wing, but I don't really like it. So I will either use it, or maybe start over. I came into a lot of cheap carbon since starting, so that is an option I did not initially have.

This was part of a project I had to make several things that appeared in the PMs of my youth, and I have reduced the number to three objects a fishing kick boat, an outboard sail unit, and the aqueon. Still on the to do list. Have the boat done.

This information is a blast from the past. As a teenager in the early 60s a friend of my Grandma, an inventor type guy teaches me to sail in his seft built monohull. One day we go for a sail out in the ocean and the wind dies down. He goes into the cabin and pulls out the 'aqueon' shown in these pictures. Calls it a swimming machine. That was made by another inventor friend. It does not have the bungee shock cord, but surgical tubing for flex tension on the front foil. But it is that swimming machine pictured. I think this was about ' 63 or '64. All wood. So he tosses it overboard and has me jump over as well to try this out. I struggle my skinny self to slip my feet and calves in and he yells to flutter kick. Struggle again before I get it. Get it I did and it took off. Felt like a dolphin for a while. Get back to the boat and he hands over a mask and and snorkel. I had a blast with that swimming machine. Wind started to pick up so swim machine time was over and back in the boat it went. We sailed back to Shelter Island marina and never saw this thing again until running across this forum while researching other propulsion systems. I sure would like to try and build one. Thanks for the pics.