Interesting Hydrodynamic Oddity

[freebeard]

www.epropulsion.com/outboards/elite/

Small portable power source quick-disconnects so you can hide it when it's not in use.



Compare with an conventional large prop on a tubular shaft.



The hydrodynamic drag drops from 0.47 to 0.14. The tiller folds to make a carry handle.



OTOH they're a thousand dollars.

[aerohead]

1) We'd need the fineness-ratio for their 'strut' .
2) That would allow us to find it's 2-D drag coefficient for the 'stalk' portion.
3) We could probably come up with the 3-D drag coefficient for the motor housing easy enough, which isn't any different from a typical electric trolling motor.
4) And, say, the 'frontal area' of the higher 2-D Cd cylindrical 'strut' for a conventional electric trolling motor would be 'smaller' than for their lower drag streamlined strut, so it's frontal area would have to be ascertained.
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I would prefer that the 'battery' be in the boat, and 'shrink' the dimensions of the submerged streamlined strut to it's structural minimum.
And there may be more hydrodynamically efficient 'propeller' designs.

[freebeard]

1) There is a two-view on the linked website but it won't copy.
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Separating the battery would eliminate the portability of the unit.

A toroidal propeller would be more efficient.

[j-c-c]

"Aerospace Grade Alum Alloy"

I'm sold, how many can I buy?

[freebeard]

Thanks for highlighting that. It sent me down a rabbit hole.

Alum is a water soluble substance having a general formula of AB(SO4)2·12H2O. It has a monovalent cation and a trivalent metal ion as essential components in its chemical composition. There are two types of alum as ferric alum and non-ferric alum. The main difference between ferric alum and non-ferric alum is that ferric alum is manufactured from bauxite whereas non-ferric alum is manufactured from aluminum trihydrate.

pediaa.com/difference-between-ferric-and-non-ferric-alum/

Alum Alloy is an pleonasm.

I was thinking about starting a different thread, but I've got you Aerospace Grade Something Something right here.

A lot of companies would use blue smoke and mirrors for a backdrop, but J P Aerospace uses pegboard.

Introducing: Ascender H1 Variant Orbital Airship

Airships in space! aerohead should note that the hypersonic airfoil is 'faster backwards'. I can't get past the fact that the plasma actuators are on the leading edge instead of trailing.

But OTOH, Elon Musk wants to go to Mars, John Powell just wants to retrieve the Hubble Space Telescope and put it in a museum.
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There is a two-view on the linked website but it won't copy.

I loaded the page and applied my brass caliper. 1 9/32 by 13/32 of an inch or 41/13 or 3.15 to 1.

[j-c-c]

Well at least I learned a new word, "pleonasm", in layman's terms, a redundant non anti oxymoron?

[freebeard]

Me too! I had to look that up.

[Piotrsko]

A grand for an electric trolling motor with an e bike battery pack? Or even better: putting lotsa amps through a USB "c" connector to recharge

[freebeard]

It says USB-C output to charge other electronic devices.

$1K may not be much to other people. I'd sooner wrap a cheap trolling motor with an airfoil battery box and put a toroidal prop on it. I'd want a mount that clamps onto the gunwale of a canoe.

[Piotrsko]

That was exactly my comment. Trolling motors occasionally show up at the thrift stores and sell for ~$25. Couple hundred for monster lion bicycle battery packs guaranteed to catch fire after import from china. Take a chunk of 6" aluminum exhaust vent and mash one side to a point............

The ad I saw indicated usb C recharge, but didn't say what was being charged. C is good to 15 amps @9 volts with special cabling and connectors