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Let's assume that a halfling is of similar build, but half the height of an adult human. If I strap a wing suit onto one, I should have a quarter the surface area, but one eight the weight of an adult human, meaning that I should have half the loading factor of a human in a wing suit, which should mean I can travel a bit slower. Now let's say I take my wing suited halfling and throw him off the top of a tall tower or tree. Lucky for him, I'm throwing him towards some sort of net or other reusable halfling-catcher located on another tower or tree some distance away.

If the halflings have roughly middle-ages technology, can they build the halfling catcher in such a manner as to not maim my half-sized missile? Is this an effective way of getting a halfling (or similar-sized creature) over potentially dangerous terrain, or is the whole scheme really just half-baked?

I'm assuming that my halflings are of roughly average build, at around a meter high and 20kgs, and have built platforms at the tops of the tallest trees in their area, which are around 100m in height. Their goal is to travel as far as possible using a wingsuit in a manner which will not result in their injury.

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  • $\begingroup$ What's wrong with a really really really really big net? $\endgroup$ – Aify Aug 10 '15 at 21:41
  • $\begingroup$ Would it slow the halfling down enough to not horribly mangle them? I feel like there's probably a reason I've never heard of people doing (or trying) this... $\endgroup$ – ckersch Aug 10 '15 at 21:49
  • $\begingroup$ We use safety nets during construction all the time, to protect people from falling off tall buildings, or decelerate/stop stop heavy objects. $\endgroup$ – Aify Aug 10 '15 at 22:15
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    $\begingroup$ Your question isn't specific enough for me to do the calculation. You're missing the height of the drop point, as well as his trajectory, distance to target, his speed, his mass (fat halfling? skin and bones?), and various other information. $\endgroup$ – Aify Aug 11 '15 at 1:00
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    $\begingroup$ "[Wingsuits]!" said Bilbo. "I should think not—in these parts! We are plain quiet folk and have no use for [wingsuits]. Nasty disturbing uncomfortable things! Make you [flat] for dinner!"" $\endgroup$ – Doug Warren Aug 11 '15 at 17:49
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Assuming a wingsuit with a 2-1 glide ratio (2 meters forward, 1 meter down), we should be able to create a massive net to catch the halfling. Wingsuits typically start gliding at approx 30mph (which is approx 13 m/s, taking approx 1.365 seconds to reach).

Rough calculation (probably not that accurate):

Starting from 100 meters up, jumping forwards, taking 1.365 seconds to reach wingsuit glidable speed, the halfling has already dropped ~9.136 meters, leaving ~91 meters to drop. If we go with a straight up conversion using the glide ratio assumed, our maximum distance traveled is 182 meters forward - but this would leave us splat on the ground, so we need to reduce this.

Let us assume the following setup.

   platforms
___                                          ___
 |                                            |
 |                                            |
 |                        badly drawn net     |
 |                            x __            |  ^
 |                                 --         |  100m
 |                                   \-       |  v
 |                                     \-_ _ /|
_____________________________________________ground

X marks the target for the halfling, where he should aim to start contacting the net. The net will be roughly U shaped with the outer end much higher than the end point. The point of the catcher is to change his downards trajectory as gently as possible into a horizontal trajectory, until we can change it into an upwards trajectory where gravity will slow him down to safety. By using a curved net, we can acheive this - kind of like how skateboarders eventually settle down in the middle of a halfpipe.

However, all that is speculation without actual math, so lets do some math.

A 91 meter drop allows you to drop for 4.30799664301 seconds before hitting the ground. During that time you will have traveled 182 meters forward, but you would have hit the ground at a speed of 39.2266 meters per second, enough to kill your halfling. Assuming your net is large enough and your target tree is really far away, you could potentially allow for a full flight time of 2 + 1.365 seconds, where he would have dropped his altitude by a total of 55.5214522231 meters - we subtract the initial 9.1 meters, leaving him with leaving him with a total distance traveled of about 90 meters forwards (Enough to fly over a river or a small hill or something like that). At that point, he is plummeting at 32.99937725 meters per second, which is quite dangerous. This is where your halfling should reach the top of the net and begin to roll down it. He'll have 45 meters (roughly) of netting to roll through, while friction and the net slow him down, eventually to the point of safety.

In short: From a 100 meter drop, the halfling can fly 90 meters forwards before probably needing to hit the catcher.

Note: You may have noticed I didn't actually do the math for how long it would take the net to stop him, or how far he would have to roll. This is because I don't know how to do the math for that part. If anyone does, please feel free to edit this answer to include the proper maths.

Note 2: I used this site for the calculations.

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  • $\begingroup$ But the halfling is lighter for the surface area, so will fall less quickly presumably? $\endgroup$ – Tim B Aug 11 '15 at 20:38
  • $\begingroup$ @TimB Not sure. I'm not smart enough to calculate that, but my gut feeling says that the surface area difference won't make too much of a difference. $\endgroup$ – Aify Aug 11 '15 at 20:42
  • $\begingroup$ physics.stackexchange.com/questions/109467/… $\endgroup$ – Tim B Aug 11 '15 at 21:45
  • $\begingroup$ Semi related and sort of cool:en.m.wikipedia.org/wiki/Cat_righting_reflex $\endgroup$ – Tim B Aug 11 '15 at 21:45
  • $\begingroup$ @TimB It's not so much the terminal velocity that I need to calculate.... not as simple as that, anyways. There's a bunch of other factors, like the length of the net, strechability, angle, change in angle over distance, etc etc.... $\endgroup$ – Aify Aug 11 '15 at 22:27
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Davinci developed his flying machine. Parachutes are fairly simple technology and operate on "drag" to deploy. Why can the halfling have a smaller parachute to deploy rather than a net. The more difficult problem is getting them high enough to merit their use. If they live on a mountain or cliff or floating city then awesome. The problem with the middle ages was lack of flying devices to merit their use. Do you have magic in this world?

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  • $\begingroup$ Welcome to the site Dynas, this is more commentary on the question than it is an answer. When you have enough reputation you will be able to post comments. List of rep based site privilages (worldbuilding.stackexchange.com/help/privileges). I would recommend you elaborate on your parachute option as an alternative but I think the question is more going for the ability of a halfling to fly as opposed to just stopping him. $\endgroup$ – James Aug 11 '15 at 17:44
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    $\begingroup$ @James actually, the question is about stopping the halflings. Took me a while to realize it too, but it appears the OP assumes the wingsuits work, they're just worried about the landing. $\endgroup$ – DaaaahWhoosh Aug 11 '15 at 19:26
  • $\begingroup$ @DaaaahWhoosh ...ok rereading it I see it too...I think a quick edit to the question may be in order for clarification. $\endgroup$ – James Aug 11 '15 at 19:49
  • $\begingroup$ @DaaaahWhoosh Actually, OP is worried about having a catcher, not the landing in particular. I'm sure OP already knows that he could just use a simple parachute. $\endgroup$ – Aify Aug 11 '15 at 20:03

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