The students were evacuated at dawn, and Aden family ethermancers set fire to the moldy old student housing. The flames were trapped within a tight crucible of wind-aspect ethermancy, and by Quinn''s second class of the day the entire structure had been reduced to ash. Soldiers and military engineers occupied much of the ashen pit where the structure once stood, dutifully constructing new furniture and installing new plumbing. By the time his final class had ended, the ethermancers had moved huge blocks of marble into the lawn. At the very center of all the activity, Kiera Blaine stood with her arms raised, channeling vast power, pure and radiant, carving apart the marble blocks as if they were sticks of soft butter, with the unseen hot knife of ethermancy.


    Because the usual workshop was occupied by Aden family soldiers, the White Chasm Aviation Club met in a mostly-empty laboratory instead. A handful of students were busy finishing their lab experiments, carefully recording measurements of the temperature of steaming water using shiny new thermometers. Knowing that Kiera and Claire would not be attending, the five students in the club started as soon as the last of them had arrived.


    "Since our field trip to see the birds," Quinn began, "me and my brother have spent a great deal of time digesting the data, and we have come to a conclusion."


    "It''s all completely useless," Seth announced.


    "Their shapes reflect the necessities of survival," Quinn continued. "Their bones are hollow. They have total control of individual feathers. Most importantly, they flap their wings in a way that our kite cannot."


    "Can we not design the kite so that the wings flap like a bird?" Vince asked.


    "We already tried a flapping design," Quinn replied.


    "Years ago," Seth added. "The tiny components were too delicate. After flapping a few times something would break. My arms were also not strong enough to flap for very long."


    "I spent some time researching architecture books in the library," Bjorn said. "Specifically, common architecture material strengths. I have a mathematical proof here that demonstrates why cloth and wood in the kite are not strong enough to survive a flapping motion. If we used stronger materials, such as metal, the thing would be so heavy that the flapping motion would not be enough to lift it off the ground."


    He offered a stack of papers to Vince.


    "Feel free to read my proof for yourself. Beyond the question of material strength, there is the question of power. Assuming we had some type of engine, the power would need to be transferred to the wings somehow. The mechanism of transfer would need to support both flapping and gliding. Such complex technology does not exist in any industry. Even if it was possible, the mechanism would be too heavy to fly."


    Vince grimaced but said nothing.


    "We should stop wasting time researching the way birds fly," Seth said. "We simply do not have the luxury. Right now, the kite isn''t safe. We need to figure out why it wants to nosedive into the ground without warning."


    "We will need to find a way to model it," Bjorn said. "It would also help if we were able to replicate the phenomenon here in the lab."


    "You say that your boat sinks without warning," Irene said. "If you can show me how it sails, I can tell you why it sinks."


    "I don''t know if..." Quinn began.


    "Wait brother," Seth said. "We would be foolish to dismiss the wisdom of such an experienced sailor."


    That''s fair, Quinn thought. He did not really trust the strange woman from the far west. Not because of her obsidian skin and glowing red-gold hair, but mostly because of the golden scales on her cheeks. He had seen that strange race of elites living in his hometown, though their skin had been pale and the scales had been dark green. In fact Quinn''s great grandmother was one such creature, and while he had never met the woman, it was from her that he inherited his green eyes.


    Without access to the workshop, and without a physical model to work with, they decided to use drawings instead. Vince was easily able to sketch the kite from various angles, and he was even able to add realistic waves and splashes of water, complete with smears of blue paint.Ensure your favorite authors get the support they deserve. Read this novel on the original website.


    "Your boat is upside-down," Irene observed. "It''s easy. If you want it to sail, you need to flip it over."


    "If we flip it over, it won''t fly," Quinn said.


    Deep down in the bottom of his pack, in one corner beside his textbooks, Quinn had an old toy that his older brother had constructed for him as a child. It was a small wooden cylinder with a shorter wooden cylinder at the bottom. The top of the smaller cylinder was cut with a star-shaped depression, and there was a long string attached to the base, wound around and around like a spool of thread and slipped through a tiny hole on the side of the outer cylinder. Finally, there was a wooden pole with a star-shaped coin at the base, and a small mechanism at the top which allowed it to hold four small cambered wings, arranged in a cross.


    Quinn assembled the little toy, then pulled hard on the string. The pole spun so fast that the wings carried it clear of the outer cylinder, all the way up to the roof of the laboratory where it bounced against the ceiling like an insect before gliding down onto a nearby table.


    "If we turn the device upside-down," Quinn said, "then we would expect the opposite to happen. It would fly down into the floor and break apart."


    "Irene, could you please explain your logic?" Bjorn asked. "I would like to try and encode it into a mathematical equation."


    At Irene''s request, Vince drew two more sketches, each with the nose pitched down progressively deeper into the water. Irene arranged all three sketches in order on the table.


    "In the first sketch, imagine the boat is sailing straight with a force from behind, perhaps because of a propeller. Then a wave strikes the nose and the nose pitches down. This exposes more of the hull to the oncoming water, which means that the nose pitches down faster. In the final image, the maximum amount of hull is exposed, which means that the maximum amount of downward motion should be expected."


    "I see the problem," Bjorn said. "It is a divergent function."


    "I have no idea what a divergent function is," Quinn said. "Can you explain?"


    "Consider the angle of the nose at time T to be a function of the angle of the nose at time T minus one," Bjorn said. "This function is divergent and grows rapidly toward infinity. The angle grows fast and the speed at which the angle grows increases exponentially, at least. The exact function may be much more aggressive than exponential. I''m not sure."


    "So how can we fix it?" Quinn asked.


    "Subtraction," Bjorn replied. "You just need to subtract off the function by a factor that is large enough to prevent the function from being divergent. Irene, if you saw this motion happen on a boat, how would you fix it?"


    "We would all be dead," Irene said.


    "Let''s say you had a crew capable of acting with infinite speed," Bjorn said. "Would that change anything?"


    "I would order the crew to carry the ballast to the back of the boat. If the back was able to sink fast enough, then less of the hull would be exposed to the oncoming water, such that the nose might even rise."


    "There is no ballast on our kite," Quinn said. "It would be too heavy."


    "Could Seth be the ballast?" Bjorn asked.


    "Absolutely not," Seth said. "I want the thing to fly straight without diving independently of what I do with my body. In other words, the kite needs to fly straight passively. In fact, I want to test the thing with sandbags before I fly on it again."


    "One thing that I noticed," Vince said, interrupting the conversation, "is that your kite does not have a tail. Birds have tails, and I imagine that your flying machine needs a tail in order to fly."


    "We already said that we are done looking at birds," Quinn said.


    "What if the tail was an inverted wing?" Bjorn asked. "No, that would make the function even more divergent. What we want is a second set of wings on the back, at the end of a long boom, perhaps at a slight angle downward. When a gust of wind strikes the craft, the wings on the rear would begin to nosedive first, which would cause the front wings to pitch up."


    "Like a seesaw," Seth said.


    "Exactly so. Now, we would not want the rear wings to pitch down so far that the kite becomes vertical. What we would want is the amount of subtraction to be exactly enough to create a convergent function."


    "Bird wings are much larger than the tail," Vince observed. "Perhaps the rear wings on the kite should be smaller?"


    "Excellent idea!" Bjorn beamed. "The rear wings could have a moderating effect, but the size of the forward wings would be such that when they pitch up, they drag the rear wings up and away from their nosedive. With smaller rear wings, we can reduce the overall weight that needs to be added to the craft."


    Vince sketched the new design. It looked similar to the original delta-wing kite, but it featured a boom extending off the back, ending with a smaller copy of the delta wing, at a slight downward angle. Meanwhile, Bjorn furiously scribbled out a series of equations to represent the different forces on the forward and rear wings.


    "Your boat is missing a rudder," Irene said.


    "We are trying to solve one problem at a time," Quinn said.


    "Just add the rudder," Seth insisted.


    As Vince worked on the sketch, Irene kept insisting that the rudder was too small, and after a few iterations it resembled a huge fishtail.


    "It looks a bit like a weathervane," Bjorn said. "Like a weathervane, perhaps the huge tail at the back will keep the nose straight against the wind."


    "That''s a good point," Seth said.


    "In fact," Bjorn continued, "the whole thing is like a weathervane in two directions."


    "So what now?" Vince asked.


    "Now we need to find some carpenters," Seth said. "And some sandbags."