Air fish

[Skye]

Just as birds serve as a good inspiration for the design of heavier than aircraft, fish are a good inspiration for neutral buoyancy aircraft. Here's a video of a model airship that uses a tail, pectoral fins and dorsal fin for thrust, direction and stability control.

 

[iNow]

Wow, that's almost surreal.

[CaptainPanic]

Waw, that's cool! Hope they scale it up! I'd love to get sea-sick in one of those once

[erynna]

i want one!

[npts2020]

WOW! and I used to think building and flying kites was pretty cool.

[Phi for All]

Completely awesome!

 

I want one too, but scaling it up? Surely the sideways motion would be too unsettling for passengers on a large-scale version. I doubt people would take a second ride on the Hindenbass.

[iNow]

Perhaps some sort of active mass damper could be used to attach the passanger cabin to the rest of the ship.

 

http://en.wikipedia.org/wiki/Tuned_mass_damper

[npts2020]

One thing seems for sure to me, is that it will never be used as a form of high-speed transportation. Maybe for touring a city or something similar.....

[bloody_thorn]

um well I can't view the video but from everyone elsesreactions I'm guessing this is quite the machine

[ironizer]

This is COOL.

 

It's just a proof-of-concept thing, not a practical passenger vehicle.

[YT2095]

it would be interesting to see the power usage of it say over 100m and compare it to more conventional propulsion (a fan blade for instance) to see which comes out the best when optimised.

although it seems a little impractical "down here" it might be just perfect for upper atmosphere work above the weather, esp if some way of making the tail move could be done by solar heating/cooling, a bit like a Radiometer.

[Mokele]

it would be interesting to see the power usage of it say over 100m and compare it to more conventional propulsion (a fan blade for instance) to see which comes out the best when optimised.

 

IIRC, airplanes have a higher cost of transport (joules/(meter*kg)) than birds, but both birds and planes have to support their weight, which this balloon wouldn't have to. The cost of swimming is actually the lowest cost of transport of any mode of animal locomotion, so this might be more economical that other methods of long-duration flight.

[CaptainPanic]

it would be interesting to see the power usage of it say over 100m and compare it to more conventional propulsion (a fan blade for instance) to see which comes out the best when optimised.

although it seems a little impractical "down here" it might be just perfect for upper atmosphere work above the weather, esp if some way of making the tail move could be done by solar heating/cooling, a bit like a Radiometer.

 

When designing any airplane, you must specify which speed you want it to have. Propulsion is more or less efficient at different speeds. This swimming thing can be efficient at low speeds, but different designs might be more efficient at higher speeds. Therefore, make sure not to compare two things that cannot be compared. Apples & Oranges or whatever other fruit.

 

IIRC, airplanes have a higher cost of transport (joules/(meter*kg)) than birds, but both birds and planes have to support their weight, which this balloon wouldn't have to. The cost of swimming is actually the lowest cost of transport of any mode of animal locomotion, so this might be more economical that other methods of long-duration flight.

 

I think that's a nice statement that is asking for a discussion. I postulate that in case of movement against a current (wind or current of a river) walking is the more economical, because ground does not move and you can push against a stagnant medium rather than a moving one.

 

I think it's logical that airplanes have more drag than something that floats. Airplanes get their lift because of the drag. However, if you plan on swimming 900 km/hr (speed of commercial jets) then I'd rethink using an inflatable airplane. It's very bulky, and drag does go up with increasing frontal surface area.

 

Your comment about swimming being the lowest cost of transport of any mode of animal locomotion seems weird: swimming takes place in a fluid called "water". When I walk, the fluid I am in is "air". Comparing the two seems silly (for example: the viscosity differs by a factor 1000). Also, the presence of the solid medium called "ground" has a large influence on our locomotion because of the potentially high friction that occurs when a moving object comes into direct contact with the "ground". Therefore, a lot of energy is being spend in avoiding such direct contact and in having only specifically evolved movement organs (called "legs") in contact with the ground while the bulk of our bodies move through the air at rather constant speed. Fish just float and never seem to worry about hitting the bottom of the ocean. They also don't seem to spend a lot of energy to avoid a collision with the bottom of the ocean (I exclude flying fish from my comment here!).

[ecoli]

How is this particular vehicle maintaining buyouncy?

[CaptainPanic]

How is this particular vehicle maintaining buyouncy?

 

Probably helium, possibly hydrogen Anyway, a gas lighter than air. Same as a zeppelin.

[Mokele]

When designing any airplane, you must specify which speed you want it to have. Propulsion is more or less efficient at different speeds. This swimming thing can be efficient at low speeds, but different designs might be more efficient at higher speeds. Therefore, make sure not to compare two things that cannot be compared.

 

That's actually why animals have 'gaits' (running vs. walking), including flying and swimming animals (whose 'gaits' are mostly described in terms of the wake pattern). For a given anatomy, each gait has an optimal speed, with cost per meter increasing away from that, and gait transitions occurring when one gait becomes less efficient than the other.

 

Of course, for machines imitating biological systems, it's all rather theoretical - actual explorations with robot fish, walking robots, etc are pretty sparse.

 

I think that's a nice statement that is asking for a discussion. I postulate that in case of movement against a current (wind or current of a river) walking is the more economical, because ground does not move and you can push against a stagnant medium rather than a moving one.

 

True, though the cost is pretty different - walking is about 7x as expensive as swimming and 3x as expensive as flying - so the headwind/current would have to be very fast to neutralize the advantage.

 

I think it's logical that airplanes have more drag than something that floats. Airplanes get their lift because of the drag. However, if you plan on swimming 900 km/hr (speed of commercial jets) then I'd rethink using an inflatable airplane. It's very bulky, and drag does go up with increasing frontal surface area.

 

I doubt it would be used for high-speed movement. Think more along the lines of loitering, high-altitude cell-phone and wireless networking stations.

 

Your comment about swimming being the lowest cost of transport of any mode of animal locomotion seems weird: swimming takes place in a fluid called "water". When I walk, the fluid I am in is "air". Comparing the two seems silly (for example: the viscosity differs by a factor 1000). Also, the presence of the solid medium called "ground" has a large influence on our locomotion because of the potentially high friction that occurs when a moving object comes into direct contact with the "ground". Therefore, a lot of energy is being spend in avoiding such direct contact and in having only specifically evolved movement organs (called "legs") in contact with the ground while the bulk of our bodies move through the air at rather constant speed. Fish just float and never seem to worry about hitting the bottom of the ocean. They also don't seem to spend a lot of energy to avoid a collision with the bottom of the ocean (I exclude flying fish from my comment here!).

 

The comparison is for ecological purposes (for instance, it explains why an aquatic species can migrate farther or forage over larger distances than terrestrial species), and to answer general questions, such as the evolution of locomotor systems in general.

 

Mokele

[alan2here]

Don't supose smaller verstions are for sale?