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View Full Version : How big would a pegasus' wings need to be?



parallaxicality
2012-May-13, 10:49 AM
Or is Earth's atmosphere too thin to support one regardless?

Perikles
2012-May-13, 10:58 AM
I imagine, without any maths to support it, that if the Pegasus wingbeat were as fast as, say, a hummingbird, then the wings could be the size they are usually depicted. Assuming the feathers were strong enough to take the strain. There are all kinds of problems here - the wing muscles would have to be a huge proportion of the bodyweight, and the energy requirements would be such that grass would be unsuitable, the stomach not big enough, and so on.

Hornblower
2012-May-13, 11:27 AM
An empty Piper Cub, with a wing span of some 36 feet, weighs about as much as a horse.

swampyankee
2012-May-13, 12:53 PM
According to the delphic wikipedia, bird wing loadings (http://en.wikipedia.org/wiki/Wing_loading#Range_of_wing_loadings) max out at about 25 kg m-2. A smallish horse, like a polo pony, is going to weigh about 450 kg. Using the limiting wing loading, this means the wing area is about 18 m2. Bird wings, iirc, have aspect ratios (aspect ratio is measure of a wing's slenderness; it's definition is span squared divided by area) that are between about five and about ten, so the pegasus' wing span would be between 9.5 and 13.5 meters.

I may do some paper reading about this. I know Robert Jones (inventor of the oblique wing concept, and one of the first people to do an analysis of the transonic performance of swept wings) has made some calculations about this (they're in his book Wing Theory) and there's a nice paper..http://www.ornithopter.net/Publications/AnAerodynamicModelForFlapping-WingFlight.pdf for everyone to read

HenrikOlsen
2012-May-13, 05:25 PM
I'll just note that that article was originally printed in the April edition of the journal.

swampyankee
2012-May-13, 10:34 PM
Well, somebody did try to build and fly a flapping wing model of Q northropi, the pterosaur with a 15 m wingspan.

Trebuchet
2012-May-14, 02:23 PM
That would be Paul MacCready (http://en.wikipedia.org/wiki/Paul_Maccready), who also pioneered human powered flight.

Pinemarten
2012-May-18, 04:37 PM
Robert A. Heinlein did a little math on it in a short story. I think it was either -We Also Walk Dogs or Waldo and Magic Inc.

publiusr
2012-May-18, 10:24 PM
Birds are almost all chest. You are tacking wings on a dense boned body where the musculature is clearly for land transport. Best to have a small horse's head on a pteranodon or something.

No Pegasi would work as depicted in art--except in a hollowed out rotating asteroid. It could run against the direction of the rotation of the ring colony when not eating and lift off keeping legs active. Then the puny wings would be more than enough in a low g closed off environment where it could fly around in Yonada, say.

Van Rijn
2012-May-18, 10:36 PM
Robert A. Heinlein did a little math on it in a short story. I think it was either -We Also Walk Dogs or Waldo and Magic Inc.

Actually, the story was "Jerry Was A Man."

mike alexander
2012-May-20, 01:23 AM
Actually, the story was "Jerry Was A Man."

Hm. I'd go for "The Menace from Earth."

Van Rijn
2012-May-20, 04:08 AM
Hm. I'd go for "The Menace from Earth."

It was definitely "Jerry Was a Man." They have advanced genetic engineering in the story and a guy wants to have a flying Pegasus made, but the genetics engineer explains the problems with that. (The main story is a "freeing the slaves" story about a chimp that's been modified to have essentially human intelligence and abilities.)