Tetropters

Those who visited the land and sea pages on the site may have wondered why there is no page on the biomechanics of flight, seeing there are pages on 'Walking with...' as well as on 'Swimming with...'. So where is the 'Flying with...' page?

The simple answer is that I am not happy with it yet. There is material on ballonts and on tetrapterate (four-winged) large flyers, and some are in fact shown on the 'air' page. But these organisms are fairly like Terran birds. For a true oddity the tetropters should be considered; in their case, 'oddness' does not reside in them having four wings. After all, Furahan tetrapterates and Terran insects also have two pairs of wings, i.e., four wings, so that isn't really extraordinary. No, the ordinariness resides in the description: 'two pairs of wings', and that says it all: the wings are arranged in pairs. Insects and birds (and Furaha tetrapterayes) all have a body scheme with bilateral symmetry, so their limbs are arranged in pairs.

Not so the tetropters. To be honest, the very first sketches I did of them did show bilateral symmetry. The top animal in the following image shows that primordial tetropter. In fact, their wing movement patterns had already been worked out, and showed a pattern that was exactly the same for each wing. So the wings showed a radial pattern, like a four-pointed star, but the body hadn't kept up. Here is one of those early tetropter designs under attack from a larger tetrapterate.

With their radial wing pattern tetropters were excellent hoverers, and control over wing movements should have allowed omnidirectional movements. But the animals still had a front and aft side. If you have a flight system that allows such tremendous manoeuvrability, why limit it with a limited body design? That is where the concept of complete four-sided symmetry came from. The next sketch illustrates the next logical step in the evolution of the tetroper concept. The top animal has bilateral symmetry, but the bottom one represents a conceptual novelty: the body follows the wings! So the entire animal now shows complete quadriradiate symmetry. By the way, I was taught that you should not mix Latin and Greek roots, and that is explains the switches between 'tetra-' (Greek) and 'quadri-'(Latin). Can't be helped.


I know of no such designs on Earth, although there are animals with five-sided symmetry (starfish, sea urchins etc.). The rest of their body scheme hasn't been worked out in much detail. The design problems are like those of octapods, with eight-sided symmetry. Tetropters too have eyes above as well as below their 'equator', and the mouth parts are all on the ground side. But I haven't done a complete drawing or painting of one yet, so the details remain sketchy - for now.

I found that the flight patterns had much in common with the movement patterns of flying and walking organisms. After all, each leg or wing or flipper moves repetitively, and any gait is no more than a cycle in which the limbs move with a specific set of phase offsets. Although there are an infinite number of ways in which you can do so, only a limited number make much sense. And so tetropters have 'walks', 'trots' and 'paces'. The first pattern shown here is a rather silly one.



I can't show the animated gif here; to see it click here.

Imagine the sphere as the animal's body, seen from below and to the side. The four wings are rotated around their axis to provide lift while going clockwise as well as moving back anticlockwise. While such a pattern does provide lift, it would also result in a net rotation effect on the animal as a whole, which is impractical. To offset that, the rotation forces need to be cancelled by having two wings swing in the opposite direction from the other two. A rough animation of just such an effect follows:


I can't show the animated gif here; to see it click here.

You can see the wings going through one another; in reality they would of course not do so. That's why I need to do a better animation, but it is not as easy to do as it sounds. In the smallest tetropters the wings clap against one another and then to move in the other direction. Many Earth insects use this technique, by the way: the clap their wings together behind their backs, and this apparently generates lift when the wings move away from one another again. In insects, there is just one such 'clap' in each cycle. Tetropters have taken the idea one step further, and the clapping occurs twice in a wing cycle, not just once.

Larger tetropters usually avoid clapping the wings together, so they reverse direction without touching. Whether this is aerodynamicaly better or simply avoids damage to the wings remains to be seen. There is so much to be researched...

Edd Cartier

Every once in a while I will show a painting or a drawing of an alien, a dinosaur or other extinct life forms that I find particularly appealing.

The first one is a drawing by Edd Cartier. I first saw it in the late seventies in a book called 'Science Fiction Ideas and Dreams' by David Kyle. The legend simply said 'Two aliens drawn by Edd Cartier for "The Interplanetary Zoo" in the Gnome Press anthology'. I wondered for a very long time how many such animals were in that book, other than the two I could find.

Today, of course, Google helps: The drawing appeared in a 1951 book called 'Travelers in Space'. here is the cover as shown on Wikipedia.


A page by David Kyle on his career in SF resulted in the following: 'I collaborated with Edd Cartier in several ways, the best being the illustrations for my story of the "Interplanetary Zoo"; this was an interesting project because the full color signature or folio in the anthology Travelers of Space was actually done from black-and-white drawings. All color was laid in by a talented printing plant technician who worked with me for the final results.' That is interesting, since it shows that the original drawing must have been in black and white.

More searching revealed a number of drawings from the book on a Japanese site.
The drawings there all have a very strong yellow background, which was not present in the book I first saw the drawing in, so I guessed it was a later addition. I mostly took the yellow away again, which brings the colours out more.


I still find this creature very appealing: it looks pensive and rather serious. Somehow it doesn't actually look very alien to me, or is that simply because I have known the image for long enough to have become familiar with it? Much as I like it, from a biomechanical point of view it is odd. What seem to be arms and legs at first glance turns out to be just one pair of limbs. These are attached to the body with what look like shoulders. In effect, the large head and small rump are suspended between these limbs. The creature must be top-heavy, and it can't have been a very elegant walker. The legs are wide apart, and it doesn't look as if its hands (feet?) can bend inwards enough to be placed directly underneath the body. That's a pity, because if you cannot do that, and still want to walk around on two feet, waddling is the only way.

Its restful appearance might be ruined if it starts to walk: it will probably draw laughs for the same reasons waddling ducks and penguins do (why is that, by the way?).

Humans on Furaha

Why are there even humans on Furaha? The idea started without them, and for a long time I thought that adding humans would only result in ecosphere destruction, turning the story into a human one rather than one about biology.

The answer is simple; without humans the stories would become dry and boring. Human interest requires a human viewpoint, at the least here and there. Some readers probably wouldn't mind if there wasn't a human in sight, but I thought that adding humans to the mix increased the complexity of the world enormously: the mixture became richer, spicier and more interesting.

This doesn't go so far that all lifeforms are exclusively viewed through human perceptions: that would take it much too far. There should be images and explanations that have nothing to do with humans.

But once there are humans, they must have a background. All of a sudden, there has to be space travel and there has to be a reason to travel. This is touched upon in the site. There also has to be a society, preferably one that does not look on animals as food only. Although references to eating wildlife may be found, Furaha is not about 'To serve Man'.

The history of the human settlement of Furaha and the Horizonists' challenge explain the current society of Furaha. Sean Nastrazurro's pathetic 'adventures' in the Spiny Desert only make sense if you know that an academic career, or at least the trappings of one, function as a rite of passage in this particular society. Sean, not well-equipped for real hardship, rather pitied himself on his Field Trip and in later life tried to enlarge everything he had done in that time. He tried to seduce young female students with his stories, but failed completely.

Sofar not much of this society has been shown on the site, although a few hints are dropped here and there. But there are reasons why people have names such as Sean Nastrazurro or Wladimir Kokkinopoulos. In this society a person can belong to various groups. One of them is cultural background, called the 'clade'; Nastrazzuro's mother is from the Italian clade, and his father from the Irish one. Another is academic achievement, and there are literally several dozens of titles one can have. The small sketch above shows a 'professisimus' in formal garb.

More on that later, when I will at one point put up a page on humans on Furaha. I will also have to think about their dress code, and their vehicles. I'm thinking about mass repulsor technology, resulting in floating vehicles with enormous inertia and a small lifting capability. That will be much later.