How feasible would gliders or the like be on a flat plain, with no cliffs to launch from?

Question

How effective or possible would flying machines that are not powered by a machine be on a flat plain?

I have a setting where much of the world is a relatively flat grassland, and the people have no magic. The inhabitants of this grassland are nomads, living in wagons ans almost always travailing. I would like to have them observe the surrounding area from a height, checking for dangers like other groups who might attack, as well as natural predators, and so they can find needed supplies like water, or wood from farther away. Would technology like gliders, wing suits, or really anything be possible to build and operate for a short length of time, as well as being small enough to be carried by a nomadic culture? Would it be possible to launch these from the top of a wagon, if no naturally high ground was close by? The technology level is roughly that of the Renaissance. I imagine hot air balloons would work, but could something like a glider or wing suit, if there was enough wind?

Answer 1

As long as you have steady winds, you should be able to fly a kite. And if you can fly a kite, then you can fly:

Man-carrying kites are believed to have been used extensively in ancient China, for both civil and military purposes and sometimes enforced as a punishment.

The (636) Book of Sui records that the tyrant Gao Yang, Emperor Wenxuan of Northern Qi (r. 550-559), executed prisoners by ordering them to 'fly' using bamboo mats. For his Buddhist initiation ritual at the capital Ye, the emperor parodied the Buddhist ceremonial fangsheng 放生 "releasing caged animals (usually birds and fish)". The (1044) Zizhi Tongjian records that in 559, all the condemned kite test pilots died except for Eastern Wei prince Yuan Huangtou.

Gao Yang made Yuan Huangtou [Yuan Huang-Thou] and other prisoners take off from the Tower of the Phoenix attached to paper owls. Yuan Huangtou was the only one who succeeded in flying as far as the Purple Way, and there he came to earth.

The Purple Way (紫陌) road was 2.5 kilometres from the approximately 33-metre Golden Phoenix Tower (金凰台). These early manned kite flights presumably "required manhandling on the ground with considerable skill, and with the intention of keeping the kites flying as long and as far as possible."

Stories of man-carrying kites also occur in Japan, following the introduction of the kite from China around the seventh century AD. In one such story the Japanese thief Ishikawa Goemon (1558–1594) is said to have used a man-lifting kite to allow him to steal the golden scales from a pair of ornamental fish images which were mounted on the top of Nagoya Castle. His men manoeuvered him into the air on a trapeze attached to the tail of a giant kite. He flew to the rooftop where he stole the scales, and was then lowered and escaped.^{[citation needed]} It is said that at one time there was a law in Japan against the use of man-carrying kites.

In 1282, the European explorer Marco Polo described the Chinese techniques then current and commented on the hazards and cruelty involved. To foretell whether a ship should sail, a man would be strapped to a kite having a rectangular grid framework and the subsequent flight pattern used to divine the outlook.

I have a personal hypothesis that the expression "high as a kite" came to be due to people smoking hashish (pot resin) and then flying with these kites, because that would give you one dope trip. Just like Mr. Ronald Amudsen in the picture below (trying the technology to see if it would help exploring the arctic).

But alas, I have no evidence to support this.

Anyway, having both flown a kite and being high as a kite (though not on a kite) in a very plain place, I can tell you that by this way you could lift a person. That person could go arbitrarily high, depending on how much hemp you got. The hemp is for the rope that will hold the kite, among other things. By the way, if your setting ever becomes a movie, I suggest including Mystic Traveler by Dave Mason as the theme for the flying scenes.

Go high enough, and besides the view, you might have enough clearing for a base jump. Being able to build a proper parachute, or even trying a DaVincian one, is a topic for another post.

Answer 2

Other posters have noted that a steady breeze can launch a kite, and that bungee cords were used to launch gliders. Modern gliders can also be launched using a powered winch to pull the tow cable and pull the glider down the runway.

winch launch

In order for the nomadic tribe to have more flexibility, they should also have developed a similar system, using a harness attached to one or a team of horses. The horses running will pull the kite or glider up to launch speed. If it is a kite, then the horses may have to continue to move until the kite reaches an altitude where it encounters a wind, but an actual glider could cast off and the pilot would then use his skills to remain aloft (looking for thermals should not be too difficult on a broad plain, but if there is terrain, then "ridge running" and other techniques can also be employed. Keen pilots should observe birds, especially hawks, and try to emulate them.

Thermals

Ridge running

The glider or kite should be mounted on a cart or chariot to accelerate, or possibly even a dolly which can be discarded once in flight (similar to late WWII German rocket airplanes like the Me 163).

Me 163 dropping the dolly on take off. You can see it in the lower left of the picture

The main weakness of this system is the pilot will likely not be able to write down observations or make sketches while piloting the aircraft or kite, and sin't going to be able to communicate his findings easily to the ground crew by voice either. Some sort of easy to understand signaling will need to be developed so the pilot can pass on observations, or an even larger machine built that can carry an observer (who would presumably write a message, tie it to a rock and then drop it down to the waiting ground crew).

The other issue, of course, is how to land safely. Another post suggests that launching criminals from kites was an interesting means of executing prisoners (presumably they lost control of the kite and plummeted to earth). Unless that issue is addressed, the supply of willing volunteers to pilot the craft will rapidly dry up.

Answer 3

A tethered hot air balloon would work, particularly if they have ready access to a fuel source for said hot air. The grass itself may work, but that makes grass fires that much more dangerous.

Another option would be A Big Kite, again tethered to a wagon. Needs wind instead of fuel. Considerably more dangerous if the wind cuts out.

If you want to be a little fantastic, you could dream up some gas-filled (helium or whatever) seed pods that the nomads gather together in big nets. They're good bird food so they'll be popped and spread their seeds, but the nomads do something to make them smell bad to birds, so they last for much longer. Or maybe they spread there seeds when struck by lightening, and are filled with hydrogen to scatter the seeds that much further. PS: don't float your balloon in a storm.

Answer 4

You could do this quite easily if you had access to fairly strong fabric & ropes (silk might work) and the necessary knowledge. See for instance parasailing: https://en.wikipedia.org/wiki/Parasailing Instead of a boat, you use a team of horses.

With proper design and good thermals, once you're aloft you could probably drop the tow line and ascend further by thermaling (though I've only done in in a sailplane): https://en.wikipedia.org/wiki/Paragliding

This has obvious advantages for nomads, since the paraglider can be packed into a fairly small package.

Answer 5

Speaking from personal experience: I completed glider training on an airfield which was on a completely flat plain, with the nearest hills too far away to count.

We could be launched by a winch, and with it we could achieve an altitude of about 220-250 meters, depending on the wind. However it was extremely rare to catch a thermal at that altitude, so winch launches were used almost exclusively for learning the basics, and to practice landing. If you were really really lucky, you could catch a thermal at that altitude, but most thermals of any usefulness over a flat terrain started above 300 meters (or 400 meters, most of the time).

So for longer flights we needed a towing plane to get us to an altitude high enough. This is obviously not available in your setting.

So, the positive: you can achieve sustained glider flight even over completely flat terrain. If you have nice weather with scattered cumulus clouds, you can hop from cloud to cloud and stay up for many hours and fly distances of hundreds of km.

The negative: in order to do that, you need to get to an altitude of at least 300 meters. The winches we used were a little too weak for that, you had to be really lucky to catch the bottom of a thermal which was strong enough to barely lift you. We used late cold war equipment (I heard more modern winches can fly you higher, but your pre-industrial tech would be much worse). Even for the winches we used, they pulled a 1 km long high tensile steel cable at over 120 km/h. The gliders had a sink rate of almost 1 m/s in still air, so we needed a thermal of at least 1 m/s, which is extremely rare to find below 300 meters over flat terrain. Your pre-industrial gliders will have a worse sink rate and worse glide ratio (you have no aluminum, no carbon fiber, no plastics), and building winches which can launch them to above 300 meters will be really difficult, if not impossible.

Answer 6

If the nomads were able to produce fabric used for solar balloons, they could lift up light gliders with wide wings to a few thousand meters and start gliding from there.

Models with longer, thinner wings would be dropped for a few hundred meters first to build up speed and then slowly tilt themselves into a horizontal position.