Aerofoil floats !

[Santiago]

A little research later and I find that lift is mostly down to the foils angle of attack and speed, regardless of whether it air or water. However, hydrofoils normally operate with a lower angle than aerofoils, especially at higher speeds to prevent cavitation (water boiling due to high pressure). But at very low speeds hydrofoils require a steep angle, as shown in the diagram of the 'aerofoil float ' .

At speeds greater than the speed of sound, however, the physics between the two types of foils becomes more complicated because air becomes compressed at about that speed. This just means that an aerofoil designed to go faster than mak 1 in air would make a lousy hydrofoil no matter what speed it went through water. In conclusion then, the aerofoil float appears to be well designed for its purpose, that being moving through water very slowly. However, the same design wouldn't work at all well on an aeroplane. Vis a vee, or whatever, the chap that invented it was a very clever man but should have called it an aqua or hydrofoil!

[Vole]

Cralusso lead the field, and there are youtube videos to demonstrate this; most of the other patterns I've made/tried tend to flutter (bound vortices?), so probably need slots. The best-known underwater foils are trawlers' "Otter boards" .

[Nobby]

Perhaps Arthur Clarke was really Arthur C. Clarke and he was testing a kind of spacecraft?

I simply called them Aerofoils because he did, in his magazine article in April 1968......."Fishing" wasn't published on the first of the month, was it.......?

Since we tend towards using Latin to promote some kind of international understanding I think it should have been aquafoil rather than hydrofoil, but then the float is designed to move sideways, not upwards. Perhaps he should have called it the steering board float? Did you know British steering boards were always on the right-hands side of the boat and the word got reduced to starboard? I don't know where port comes from but maybe the rum ran out......?

[Stour Otter]

He who remembers the "Flyng Sub" in "Voyable to the Bottom of the Sea" knows that these things are possible.

[QuinetteCane]

Before it became Port it was Larboard Nobby. At some time they realised shouted
Instructions aboard a storm tossed sailing ship could be easily misheard. Dunno why
It became the other name for harbour tho'.

[SeanM]

Cos that was the side that the harbour was when they attached themselves to it.

[SeanM]

At the speed that water passes over one of these floats it's unlikely that the shape of the cross section has much effect on how it works. A simple flat cross section will work just as well, because, as Santiago discovered, the forces are generated by the angle of attack of the float. A pike fishing friend of mine uses a "side planer" for fishing the far bank of rivers. These consist of a thin, flat vane which is held at an angle by a wire contraption. They were developed in the US for trolling a lure or bait out to the side of a boat.

[Paul D]

At the speed that water passes over one of these floats it's unlikely that the shape of the cross section has much effect on how it works. A simple flat cross section will work just as well, because, as Santiago discovered, the forces are generated by the angle of attack of the float. A pike fishing friend of mine uses a "side planer" for fishing the far bank of rivers. These consist of a thin, flat vane which is held at an angle by a wire contraption. They were developed in the US for trolling a lure or bait out to the side of a boat.

Think your confusing drag with lift sir, a foil ( aero or hydro ) creates a negative pressure on it's top surface due to the fact that the medium moving across it ( air or water ) has to move faster and because nature will always fill a vacuum in effect sucks the foil upwards, hence lift ( if it worked in reverse ie: the bottom surface worked it would be called push!) .
With a flat plate section if you alter the angle of attack and present the lower surface to the flow the flow will push the surface away but this will only work if the flat plate is somehow constrained, in this case by the anglers line, left to its on devices the plate would tumble, think of how a rudder on a boat works .

[Vole]

An aerofoil is usually attached to something (an aeroplane, for instance) to pull it through the air, too.
Left to its own devices it just lies there on the bench.

[Nobby]

Since these floats are not powered surely they can only work by the force of drag??? In which case the 'foil' is probably superfluous...???


I put wires on mine so that I might fiddle with the angle of water flow....I really should at least try them out......daft not to have.....