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Old 08-31-2011, 08:16 PM   #1
Agemegos
 
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Default Flight on na-Barsoom

About the time of the First World War Mars was known to have surface gravity of 0.38 gee, but was also believed to have a thick atmosphere containing water vapour and oxygen, and with sufficient "heat-retaining power" to keep the oceans above freezing despite Mars' receiving only 39% as much insolation as Earth. That requires a pretty thick atmosphere, even with plentiful CO2, methane, and other GHGs (perhaps released by genetically-engineered areoforming organisms).

Anyway, with thicker air comes more lift for either lighter or heavier-than-air craft. And with lower gravity heavier-than-air craft require less lift. (Lighter-than-air craft receive less lift in exact proportion to their requiring less.)

So we might see more, cheaper, better aeroplanes, but not much advantage to airships, right? And bigger birds? How close do we get to parahumans with functional angel-wings?
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Old 08-31-2011, 09:50 PM   #2
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Default Re: Flight on na-Barsoom

IIRC, there was an "atmosphere plant" on Burrough's Barsoom. It was a huge facility that could have been regulating greenhouse gases. One of my favorite little games when I was reading them was to regard Carter as an unreliable narrator, then find out what was really going on.

Magnus lift spheres could work for airships, too. You could mount the spheres at the corners of an airship, it seems to me (however many corners an airship may have).
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Old 08-31-2011, 10:54 PM   #3
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Default Re: Flight on na-Barsoom

Assuming atmospheric density equal to modern earth, then I would guess you would just assume 1/0.38 as massive as on earth. You would see 105 pound creatures flying like 40 pound ducks on earth.
That is still a bit off from heavier humans flying with much less efficient strap on wings.
Human powered flight might be a bit easier, since on earth it's TL7 with very compact fit men doing it.
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Old 08-31-2011, 11:13 PM   #4
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Default Re: Flight on na-Barsoom

Quote:
Originally Posted by Flyndaran View Post
Assuming atmospheric density equal to modern earth, then I would guess you would just assume 1/0.38 as massive as on earth.
That would give me the same wing loading on a wing the same size. But if we assume that a 126-lb Parahumanus aves has larger wings than a 40-lb duck don't we get somewhere?

Suppose I take a Dalmatian pelican massing 15 kg, 1.8m long, and with a 3 m wingspan, scale it up by 59%, and take it to na-Barsoom. Its weight goes up by a factor of 1.52, but its wing area goes up by a factor of 2.52.

60 kg is not a big man, and 4.75 m is a huge wingspan. But I can even bring the wingspan down a little and still soar like a pelican. 3.7 m wings on a 60-kg bird on Mars would give the same wing loading as a pelican on Earth.
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Last edited by Agemegos; 08-31-2011 at 11:25 PM.
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Old 09-03-2011, 03:34 PM   #5
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Default Re: Flight on na-Barsoom

A few thoughts - your lift-to-drag ratio doesn't change. The ratio of the amount you go forward to the amount you sink in constant speed gliding is your lift-to-drag ratio, so you go just as far when gliding. What happens is that you sink slower, but also go forward slower. Expect soaring critters like eagles or albatrosses to be slower by the ratio of Martian gravity to Earth gravity.

Getting aloft in the first place is easier. If you are treating your flier as a fixed wing aircraft (very appropriate if it is a fixed wing aircraft, not so much if it is a bird or bird-man or pterosaur or bumblebee or something), then you equate the lift of 0.5 C_l A rho v^2 to the weight M g (where C_l is the coefficient of lift at the stall angle, A is the plan area of the wings, rho is the atmospheric density, v is the airspeed, M is the mass, and g is the local gravitational acceleration measured in units consistent with the rest of everything else and not necessarily with respect to Earth's gravity). You see that the stall speed varies as the square root of (g/rho) for a given flier. For flapping flight, you can get airborne at a lower speed than with fixed wings.

Hovering flight becomes easier. You need to exert a force equal to your weight (plus any losses due to drag), which is smaller.

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