Half a billion years of streamlining

[mattW]

Its easy; imagine two hungry samon that have to swim upstream to breed, one more aero (or hydro) than the other. They both have the same amount of energy stored as fat in them. The efficient fish will use less energy and make it's mate whereas the other fish will die. The surviving fish gets to breed and pass on its steamlininess whereas 3-box fish gets a Darwin award. Unfortunately there is no proverbial river that automakers have to swim up to create a new model... the just do whatever sells best.

[aerohead]

Originally Posted by trebuchet03

On the subject of nature (very good write up, by the way).... I've yet to find an instance of vertical wing tips in nature Some birds have fanning feathers at their wing tips - but that's physically very different...

I liked donee's post about animals ability to morph their bodies to achieve direction without the need of the weather vanes we see on aircraft.I know NASA and MIT,and others are working on aircraft which will be shape-changers during flight.I will watch with much interest as this technology advances.No doubt,active aerodynamic appliances will make inroads into the road vehicle arena,as energy prices,and competitive forces spawn reactive engineering counter-punches.Hope so!

[Otto]

You would enjoy reading Dr. Heinrich Hertel's "Structure, Form, Movement" book, which looks to Nature for elegant engineering solutions.

The fastest swimming fishes (i.e., tuna, shark, etc.) have max thickness at 44.22% of length, for optimal streamlining. Otherwise, they don't get breakfast, but are breakfast. They've had, oh, ~65 million years to work on it. We do well to listen to Nature.

Nature never made a Kamm back because the tail is where the propulsion comes from. Besides, a fish tail is no fun while parking or in traffic.

[newtonsfirstlaw]

The rule in history as we are finding out is that efficiency wins in the long term. We have morbidly obese people because plentiful food is the exception in history rather than the rule. When we have more humans and less food those naturally fat people are going to come into their own, provided that the less efficient high metabolism people don't have other advantages in their favor provided by that high metabolism.

And look at our brains. That much parallel processing ability and such little energy usage compared to the computation achieved. If that had to be done in silicon, the wattage would be incredible. But natural selection brings efficiency.

[basjoos]

Originally Posted by Otto

Nature never made a Kamm back because the tail is where the propulsion comes from. Besides, a fish tail is no fun while parking or in traffic.

Squids, cuttlefish, and octopi are jet propelled and don't have tails. When moving fast, they combine their tentacles into the shape of a boattail rather than a Kammback. But if all else was equal, a Kammbacked tentacle package would be preferable from a predator avoidance standpoint, since it doesn't stick out as far as a boattailed tentacle package and would be harder for a pursuing predator to grab. So a boattail must provide drag reduction and higher speed benefits that counteract its additional length and mass

So far, the boattail on my car hasn't been a detriment in parking or in traffic and I've been driving with it on my car for 2 years.

[Otto]

Originally Posted by basjoos

Squids, cuttlefish, and octopi are jet propelled and don't have tails. When moving fast, they combine their tentacles into the shape of a boattail rather than a Kammback. But if all else was equal, a Kammbacked tentacle package would be preferable from a predator avoidance standpoint, since it doesn't stick out as far as a boattailed tentacle package and would be harder for a pursuing predator to grab. So a boattail must provide drag reduction and higher speed benefits that counteract its additional length and mass

So far, the boattail on my car hasn't been a detriment in parking or in traffic and I've been driving with it on my car for 2 years.

Hmmm. Interesting about parking/traffic.

Squid go tentacle-forward, gathered into a fairing shape, though octupi have tentacles trailing, also in streamlined configuration. Both are jet propelled, as opposed to wagging their tails like normal fish and dolphins, as I understand it.

BTW, have you tested your car with vs. without the front end mods, but with rear end mods, to see how much the front fairing helps?

[aerohead]

Originally Posted by Otto

You would enjoy reading Dr. Heinrich Hertel's "Structure, Form, Movement" book, which looks to Nature for elegant engineering solutions.

The fastest swimming fishes (i.e., tuna, shark, etc.) have max thickness at 44.22% of length, for optimal streamlining. Otherwise, they don't get breakfast, but are breakfast. They've had, oh, ~65 million years to work on it. We do well to listen to Nature.

Nature never made a Kamm back because the tail is where the propulsion comes from. Besides, a fish tail is no fun while parking or in traffic.

Thanks Otto! I wrote the title and author info,and will try and run down a copy of the book.He may be the resource used by others when making claims about aero/hydro efficiency in the animal kingdom.Thanks again,Phil.

[LostCause]

I don't see nature as providing any aerodynamic benefit beyond inspiration. It took mankind thousands of years to master flight primarily because he tried to emulate nature. Look at DaVinci's flying contraption:

Da Vinci Flying Machine


What nature did was inspire man to fly. Without birds, flying bugs, or clouds I doubt man would have ever learned to fly. Today, people try to tie in nature with their designs because it has a romantic element. Aerovironment's Solaraycer was designed after a pumpkin seed, yet a pumpkin seed is not inherently aerodynamic...

Lastly, nature does not think. Everything you see around you is (as far as we know) not a master plan, where evolution is heading in a particular direction. What you see exists solely because it was able to survive. Man is not at the "top of the evolutionary ladder," he is simply a leaf on the evolutionary bush. The most evolutionary successful creatures are single-celled organisms like bacteria, who have remained virtually unchanged for billions of years. As far as we know, nature thinks as much as planets do while orbiting stars trillions of miles away.

- LostCause

[aerohead]

Originally Posted by LostCause

I don't see nature as providing any aerodynamic benefit beyond inspiration. It took mankind thousands of years to master flight primarily because he tried to emulate nature. Look at DaVinci's flying contraption:

Da Vinci Flying Machine


What nature did was inspire man to fly. Without birds, flying bugs, or clouds I doubt man would have ever learned to fly. Today, people try to tie in nature with their designs because it has a romantic element. Aerovironment's Solaraycer was designed after a pumpkin seed, yet a pumpkin seed is not inherently aerodynamic...

Lastly, nature does not think. Everything you see around you is (as far as we know) not a master plan, where evolution is heading in a particular direction. What you see exists solely because it was able to survive. Man is not at the "top of the evolutionary ladder," he is simply a leaf on the evolutionary bush. The most evolutionary successful creatures are single-celled organisms like bacteria, who have remained virtually unchanged for billions of years. As far as we know, nature thinks as much as planets do while orbiting stars trillions of miles away.

- LostCause

The Solaraycer demonstrates a 400-mpg vehicle,if fitted with gasoline internal combustion engine with power to provide contemporary levels of acceleration.With concessions made to ingress/egress,survivability,real wheels/tires,emissions controls,etc.,could represent a 200-mpg commuter vehicle in days of plus-$3.00/gallon fuel and U.S.reliance on the Persian Gulf.That's an inspiration for myself and others,no matter its origin.It's origin was a pumpkin-seed,so given the success of Aerovironment's endeavor,I see no reason to berate forms found in nature,and I will personally continue to borrow heavily from the same architecture that inspires the likes of M.I.T.,NASA,Electric Boat Division,General Dynamics,Corp.,Lockheed/Martin,Airbus,Boeing,Grumman,Zeppelin Werke AG,McDonnel/Douglas,Rockwell International,Scaled Composites,Old Town,Winchester,Remington,Marconi,Cal Tech,Mercury Marine,etc..

[basjoos]

Originally Posted by Otto

Squid go tentacle-forward, gathered into a fairing shape,

BTW, have you tested your car with vs. without the front end mods, but with rear end mods, to see how much the front fairing helps?

Squid can go either tentacles-forward and tentacles-backwards (the advantage to being propelled by a directional nozzle). They go tentacles-forward for short distances when capturing prey (the tentacles will flare outwards to capture the prey at the end of the brief forward sprint. But they spend most of their time going tentacles-backwards (especially when they are in a hurry).

I didn't have a SuperMId when I installed the nosepiece and boattail (the boattail was installed earlier than the nosepiece), so I could just go with the change in coasting ability resulting from installing the mod. The boattail produced a larger improvement in coasting ability than the nosepiece, but the nosepiece produced a greater than anticipated improvement. The nosepiece resulted in about the same amount of coasting improvement as when I installed the smooth underbody.