Scintific Dragons, page 2

Originally posted by daniel191159

During my senior year in high school I had a fascination with flight. I found a picture of a dragon and a small figurine that mirrored it in every way that was important. I calculated its mass, wing span, the surface area of its wings, running speed based on muscle and skeletal structure, drag due to surface area, and lift generated by running with wings outstreached. After about three months of research, checking, double checking and recalculating I determined that the particular specie I was studying could, in fact, glide had it existed. The lift it could generate was enough for it to carry approximately 50 lbs before it would not generate sufficient lift to become airborn.

You wouldn't happen to have any of those workings still would you? I'm quite intrieged

Some useful maths at Mathematical Power requirements for flight

Also I found:

"Flying

The key to wings is surface-volume ratio. Body mass and volume increase as the cube of size, so that an adult rabbit 10 times as long as a newborn will weight 10x10x10 or 1000 times as much. On the other hand, bone strength increases as the cross-sectional area of the bone, or as the square of size. Thus, an elephant 10 times as tall as a dog will have 1000 times the body mass, and need 1000 times as much bone strength. Its bones will have to be 31.6 times as big in diameter as the dog�s (31.6 x 31.6 = 1000). Thus the elephant�s bones will be much thicker in proportion to their length than the dog�s. Conversely, a mouse 1/10 as large as the dog has to support only 1/1000 as much mass and needs only 1/1000 as much bone strength, so mouse bones are much thinner than dog bones in proportion to their size. Bone proportion is why a snapping mousetrap is painful for a human but fatal for a mouse. A dog, a mouse, and an elephant all scaled to the same size would look quite different and it would be immediately obvious which is which.

If we apply these scaling laws to humans, an adult three times the size of a baby would weigh 3 x 3 x 3 = 27 times as much. A typical baby is about 55 cm (22 inches) long, an adult 165 cm (67 inches) tall. If the baby weighs 3 kg (6.6 pounds) we'd expect the adult to weigh 81 kg (178 pounds). That's a bit on the heavy side for a 165-cm human, because babies are chunkier than adults. That's partly why they're cute.

Now, air resistance is related to surface area and varies as the square of size. Objects falling through the air eventually reach a terminal velocity (for skydivers it is about 200 km/hr.) As organisms get smaller, their mass goes down as the cube of their size but air resistance as the square. Thus, a rat 1/10 as big as a human has 1/1000 the mass, but 1/100 the air resistance. In other words, in proportion to its size, a rat encounters ten times as much air resistance. Small organisms encounter such large air resistance that they can easily survive a fall that would kill a human.

Surface-volume ratio explains why flying birds cannot be very large. Mass goes up as the cube of size, but lift, which is related to wing area, goes up only as the square of size. So does bone strength to support the wings and muscle cross-section to power them. So a big bird compensates for its large body mass with larger wings, thicker bones, and thicker muscles, and a much greater tendency to glide. Big birds like condors with 4-meter wing spans are near the limit of size for birds, and they have far larger wing spans in proportion to their size than sparrows. During the Mesozoic there were flying reptiles with bigger wing spans. We have complete fossils of flying reptiles with 7-meter wing spans and partial fossils of creatures that may have had wing spans of 15 meters or more. We�re not sure how much powered flight capability they had, or whether they were solely gliders, and the bodies that have been found are about the size of the largest flying birds today. They could surely not have carried off a human, as the flying reptiles of Jurassic Park III or Dinotopia did."

From here

Meh, I've got a lecture in Cosmology now, but I'll try to find some more useful sites and do the math later

Have a good day people!

[edit on 8/11/2004 by Slashpepper]

[edit on 8/11/2004 by Slashpepper]