# "The Menace from Earth" flying sequence

1. Jul 6, 2017

### Noisy Rhysling

In the eponymous short story Lunarians have a large dome they can use to fly under their own power, using wings they rent.

BUT, let's posit a person who regularly runs 26.2 marathons on Earth. Is this person fit/strong enough to actually fly in that arena? SWAGs accepted.

2. Jul 7, 2017

### Staff: Mentor

You meant 26.2 mile marathons right not 26.2 marathons of 26.2 miles, right?

Pheidippides (aka Philippides) had trouble running one after a protracted battle and runs to Sparta (140 miles).

https://www.awesomestories.com/asset/view/Legendary-Runner-of-Marathon-Pheidippides

and your question is that a super athletic Earther can fly in the Lunar environment.?

I'm not sure unless the Earther marathoner is using his legs to power the wings since the marathon doesn't help much with upper body strength.

3. Jul 7, 2017

### Noisy Rhysling

I hadn't heard of Pheidippides, at least not before 1963.

And the marathon thing is a general estimate of health. The lungs would be important, I think.

4. Jul 7, 2017

### Staff: Mentor

The question is using legs or arms to power the wings. The marathon can produce strong legs.

5. Jul 7, 2017

### Noisy Rhysling

But my criteria is simply a healthy person.

6. Jul 7, 2017

### Staff: Mentor

Then id say no. Recalling the human powered flight they used bicyclists to generate sufficient power.

7. Jul 7, 2017

### Noisy Rhysling

This was on the Moon?

8. Jul 7, 2017

### Asymptotic

If I recall the tale, Heinlein's protagonists flew around in a huge recreational cavern that doubled as an air storage reservoir where pressure was maintained at above 1 standard atmosphere.

Gizmodo has an article on whether human-powered, winged flight is possible on Titan, and briefly mentions the moon (their answer is yes, but only with a kick-start). I'll lean yes too, considering Heinlein had a good background in math and physics, and attempted to be as grounded in the possible as his story lines would allow.

9. Jul 7, 2017

### Noisy Rhysling

Sweet. Now to build it. We need several, thematically separated by tunnels with drafts that allow one way traffic only, to avoid jams.

10. Jul 10, 2017

### stefan r

It also depends on what kind of flying you intend to do. We have a lot of hawks and eagles on the east coast. They frequently hang in the air. If you are close or use binoculars you can see that they are making slight adjustments with feathers. But they can gain altitude on updrafts without flapping. Sometimes I see little song birds beating up the hawks (crows too). It looks like they are pecking the tail feathers out. Hawks and eagles try to escape but can not flap hard enough to outrun the little birds. The songbirds have a curve radius, angle of attack, and sometimes a speed advantage.

Songbirds are almost always flapping or losing altitude in a glide/dive. Bats are crazier in the air than songbirds. Humming birds are even less energy efficient. Dragonflies can do insane stunts by using double wings in or out of phase.

A human hovering with faerie wings would probably require to much energy. You need an extra set of arms plus a lot of power if you want the dragonfly maneuverability.

I expect the cooling tower next to the fusion energy plant will have a nice updraft. Especially if it is air cooled.

11. Jul 11, 2017

### 256bits

Might as well us a parasail or hang glider with the updraft.

I do think the CG of a human is in the incorrect location wrt to the arms and attached wings for a hovering horizontal position of the body.
Perhaps people would like to fly standing up - I don't know.

12. Jul 11, 2017

### Noisy Rhysling

Keep in mind that we're on the Moon.

13. Jul 11, 2017

### stefan r

Right, gravity is 0.165g. An albatross has a lift to drag ratio of 20. A gull has L/D around 10, a house sparrow around 4 and a flying squirrel about 2.

A flying squirrel apparatus could be incorporated into safety gear for climbers. Skiers at a lunar resort would need to factor in wind. You could lose contact with the snow for awhile. Hugging a lift pole at 60 kph hurts the same regardless of gravity. Skiers might opt for aerodynamic outfits like Olympic racers. Some might want webbing in order to break or to steer away from an obstacle. You could also put fins on the ski poles as rudders/stabilizer.

14. Jul 11, 2017

### stefan r

On earth terminal velocity is around 195 kph. With 1/6th earth gravity that should be √1/6. So terminal velocity would be around 80kph.

If you have a very large dome it will take a lot of cooling during the 336 hour day and a lot of heating during the 336 hour night. The loonies need to build a heat exchange system and use the heat capacity of the rocks to balance the temperature. So it makes sense to have a 300 meter vertical shaft with oxygen or air blowing up. You could set the diameter such that a 90 to 100 kph wind would move about the right volume of air. In order to get down the shaft you would have to dive (or at least cannon ball). Any type of wing or even puffy clothes would make it harder to go down. After diving most of the way you could spread your arms and legs to pick up vertical speed. You should be able to shoot past ground level.

15. Jul 12, 2017

### Noisy Rhysling

Heinlein considered the heating/cooling problem, something I forgot to mention. The dome is underground.

Is "underground" an accurate term? "Underluna"?

Anyway, Andy Weir's next book is due out in November, murder mystery set on the Moon. :drool: (That second book is so critical.)

16. Jul 13, 2017

### newjerseyrunner

Fly with their arms with wings? Very unlikely. Marathoners can do what they do because humans evolved to be distance runners. Our legs and butts and huge. If you were to use your arms, you would tire very quickly because you would be using the latissimus dorsi muscles, which have not evolved for continuous use. I imagine it'd be like doing a butterfly stroke in a pool, except you'd be completely vertical. It wouldn't be like gliding with a wing suit, if your center of lift is your arms and your center of mass is around your hips, you will have to be vertical.

17. Jul 13, 2017

### Noisy Rhysling

And that's on the Moon?