How fast can we swim with a dolphin like propeller?

[JonathanCole]

Originally Posted by icetreader

The implication of this theory is that the apparent swimming drag is actually lower for an undulating body than that of the rigid equivalent. This is in complete contrast to the traditional assumptions that estimate the apparent swimming drag to be three to five times that of the rigid-body equivalent, due to the increased friction drag and inertial recoil energy lossesassociated with BCF undulatory motions...."
(Thanks to Guillermo for the article)

Yoav

What I find interesting is that if you do a dolphin like undulating (traveling wave) motion underwater at the right frequency and amplitude you can actually experience this yourself for short periods of time (our bodies are not well adjusted for this type of motion for an extended period of time, it seems). It feels as if the resistance becomes substantially less.

The question is how to create a drive that will duplicate a variable traveling wave so that you can find the sweet spot of amplitude and frequency. The animal can tell what works because the exertion is reduced.

[icetreader]

Originally Posted by JonathanCole

The question is how to create a drive that will duplicate a variable traveling wave so that you can find the sweet spot of amplitude and frequency. The animal can tell what works because the exertion is reduced.

Jonathan,

Two thoughts:
1. The animal species (e.g. dolphin, shark, salmon etc.) was shaped by traveling waves, among other things...
2. The animal doesn't have a drive - The animal is the drive, from head to tail.

I think that in order to achieve significant results in terms of efficiency we should be ready to think about
1. New hull forms that are completely integrated with the tail propeller, and 2. Extreme simplicity, i.e. very few moving parts.

This requires both a lot more research and extensive use of flexible materials.

I'm working on a tail propeller for my W Kayak (Kjell has been kind enough to advise me) but although I'm excited about it I have no illusions about its overall effectiveness since it's just an add-on propeller for an existing (twin)hull.

Yoav

[VladZenin]

Jonathan,
I think we are at the beginning of understanding how fishes and dolphins swim. I have very limited experimental potentialities but nevertheless I decided to find out how the length of the flexible band in my propulsion device exerts influence on propelling efficiency this device. I sow that increase in length more than one and half wavelength did not increase pushing power. You can see (fig.7 at said article) that fishes have the length just like this.

[benmww]

doe anyone know the approximate muscle power a dolphin uses to get to 35mph?
i think it's in the neighbourhood of 4hp

[masrapido]

Originally Posted by benmww

doe anyone know the approximate muscle power a dolphin uses to get to 35mph?
i think it's in the neighbourhood of 4hp

and...?

are you trying to point to a huge power requirement for a small weight or to a small speed given the power applied?

(how 'ye doin' Jonathan?! I've been busy studying overseas lately. hope you are OK.)

Happy New Year to all my fellas argonauts.

[VladZenin]

Originally Posted by benmww

doe anyone know the approximate muscle power a dolphin uses to get to 35mph?
i think it's in the neighbourhood of 4hp

See for example the article of Frank E. Fish in the Journal of Experimental Biology http://jeb.biologists.org/cgi/content/full/208/6/977