Swoops and skimmers are the primary means of transportation in Metamor City. Living in a metropolis that is, essentially, five layers of city stacked on top of each other leads to certain problems, not the least of which is how you can drive safely in that environment. Sure, the roads are all solid enough, but if you get forced off of the skyway during rush hour on the city's third level, you'd better be able to fly.
Enter the skimmer. Skimmers are the spiritual successor to the automobile (which is still in use in much of the rest of the world, by the way), essentially a hovercraft for two or more people that features an enclosed cabin. Swoops are descended from motorcycles, and can carry one or two people that are exposed to the elements as they ride in the vehicle's saddle. Swoops are faster and more maneuverable than skimmers, while skimmers are larger, safer, and more versatile.
Technical Specifications
Both skimmers and swoops use spelltech in order to fly and maneuver. In either case, the vehicle's electric motor is connected by frictionless driveshafts to a pair of long metal rods called drive turbines. (The motor is not physically connected to the turbines; each turbine is spun by the electromagnets in its driveshaft, which surrounds the turbine at a distance that allows it several inches of movement in any direction, for reasons that will become clear shortly.) These turbines are made from a special, highly durable type of steel made using Elven forging techniques, so they are especially long-lasting, rust-resistant and easy to enchant. Each turbine holds four cylindrical disks along its length, each of which bears a variety of carefully-enchanted runes that are connected by the runes that run the length of the rod. Each turbine is connected to two piston-equipped control rods at either end, which can move either the front or back of the turbine left, right, up or down, within the limits of the range of motion allowed by the driveshaft.
The enchantments on the drive turbines are such that when they are spun, they weave a mana field that generates a repulsor field around the vehicle. This modified levitation spell causes the vehicle to push away from any solid or liquid mass that is not part of the vehicle, its passengers or its cargo. The field grows stronger the faster the turbines spin, so by varying the throttle the pilot can vary the strength of the repulsor's effect. Just what that effect is depends on the orientations of the turbines with respect to the vehicle and with respect to each other.
In the neutral position, the turbines sit side by side parallel to the long axis of the vehicle. In this mode, running at idle speeds, they will exert a repulsion force sufficient to hold the vehicle steady in the air. Increasing the speed of the turbines beyond idle will cause the vehicle to float upward (since there is more mass in the ground below the vehicle than in the air above it); throttling back to sub-idle will cause the vehicle to begin to fall downward. Safety mechanisms built into the flight computers of modern skimmers and swoops prevent them from crashing into the ground due to sub-idle turbines or turbine/engine failure; an emergency enchantment hidden within the vehicle triggers a shield spell that will gently break its fall when it nears the surface. This shield is like an airbag, in that it only works once; it must be recharged after every "crash". (Incidentally, the shield also greatly reduces the odds of traffic fatalities: it will work almost as well in a skimmer-to-skimmer collision as in a skimmer-to-ground collision.)
To move the vehicle forward, the control rods angle the rear ends of the turbines toward each other. This strengthens the repulsor field to the rear while weakening it to the front. The net result, by the Third Law of Mechanics, is that the vehicle is pushed forward with a force equal and opposite to the repulsion force being exerted on everything behind it. Similarly, angling the turbines inward at the front exerts a backward force, causing the vehicle to slow down (or accelerate in reverse).
To gain altitude, the control rods angle the turbines down in front and up in back; this increases the repulsion force in front, causing the nose of the vehicle to be pushed upwards. Nosing down requires the opposite movement.
To roll the vehicle, rotating it around its long axis, the control rods raise the turbine on one side and lower the turbine on the other side. The rod closer to the ground will exert the greater repulsion force, and as a result the vehicle will roll toward the side with the elevated turbine.
To yaw the vehicle, rotating it around its z-axis, both turbines must be kept parallel to each other and angled to the left or right with respect to the vehicle. Angling the front ends of the turbines to the right will exert a greater force in that direction, causing the vehicle to yaw to the left, and vice versa.
As noted above, spinning the turbines increases the repulsion force, and therefore the acceleration in the direction determined by their orientation; but the turbines need not be spun at the same speeds. If the left turbine is spun faster than the right turbine, it will exert a greater force than the right turbine; this will cause the vehicle to side-slip to the right.
Controls
These controls may sound somewhat confusing, but vehicle designers have found ways of making them intuitive. In modern skimmers, control is "fly-by-mind": a spelljack headset links the skimmer's flight computer directly to the mind of the pilot, allowing for rapid, natural maneuvering in all three dimensions and around all three axes. Swoops use the yoke, pedals and throttle method:
- Thrust pedals: There is one of these for each foot, each of which can be angled forward or backward. To move the swoop forward, the pilot angles both pedals forward; to brake or go backward, she angles both of them backward. Angling them in opposite directions will cause the swoop to yaw in the direction of the one that is angled forward; angling one forward while holding the other at the neutral position will cause the swoop to side-slip in that direction.
- Flight yoke: This is shaped like a cross between the handlebars of a racing bicycle and the flight yokes common on RL private airplanes. The pilot turns the yoke left or right to roll the swoop in that direction; pushing the yoke inward pushes the nose of the swoop down, while pulling it outward pulls the nose of the swoop up.
- Throttle: On most modern swoops, this is a thumb switch on the flight yoke. It naturally defaults to the neutral position, for level flight; holding it up causes the swoop to rise, while holding it down causes the vehicle to fall.
Older skimmers use a variety of control schemes: some based on joystick, throttle and rudder pedals, some based on a flight yoke and automobile-style pedals, and some based on stranger, hybrid techniques. Skimmers developed unevenly, growing out of the early automobile industry, and there was much experimentation in the early years to determine which control system was easiest for drivers to use. The spelljack system is the first truly universal standard for skimmer controls since the vehicle's invention.
History and Influence on MC Geography
Skimmers and swoops were both invented around 1930 CR, only about four decades after the invention of the automobile. Of course, neither autos nor skimmers and swoops looked much like they do now in those days — they've gone through many years of evolution and refinement. In any case, the development of skimmers and the growth of Metamor City have gone hand in hand; it wasn't until airborne personal transportation became truly practical that the city was able to really expand into the clouds. Since that time, however, the growth of Metamor City has been almost exponential.
Sources: Original MK2K entry- Transportation/Skimmers & Swoops
