Absolute Ceiling

by Fluid Apple

Rating: teen
Tags: My Little Pony: Friendship is Magic, Rainbow Dash, Romance, Pinkie Pie, Twilight Sparkle, Applejack
Length: 4008

The dynamics of pegasi flight are discussed, included with some romance herein.

Twilight has been spending time reading up on the dynamics of pegasi flight for years as she's been learning how to use her new appendages. Rainbow Dash has proved to be a great flight instructor. Now Twilight feels she finally has enough knowledge to speak to Rainbow about the limits of pegasi flight. But what is with this desire to learn more? Is it simply a burst in curiosity, or something more?

Written for Sleepyted for Jinglemas 2021

Published 2021-12-27 08:10:01 UTC
Last updated 2021-12-27 08:10:01 UTC

Head in the Clouds

“There are limits to pegasi flight that can be theorized by science. The force of Lift generated by the wings has to be greater than the force of your weight in order to maintain steady level flight. Steady level flight is easier to map out because Lift is equal to Drag. Lift is therefore equal to the coefficient of lift times your weight, and the coefficient of Lift is dependent only on the density of air, the speed of air passing over the wings, and the area of the wings themselves. A little bit of Lift is also generated from the body, but the wings do most of the work. Therefore, a pegasus that can maximize their wing area and flap with enough power to overcome their weight can reach the limits of the sky itself: the density of the air. Air is made of 78% nitrogen, 21% oxygen, about 1% Argon, .03% carbon dioxide, .001% Neon, .0002%....”

Rainbow Dash sat in a desk chair within the Golden Oaks Library with her head in her hooves to use as a pillow. Sheer willpower alone was the only thing keeping her awake as Twilight stood by her chalkboard filled with equations and diagrams. Truly, Twilight must be doing this to kill her. Twilight, who had received wings much later than Rainbow was born with them, was trying to lecture the greatest flier of all time! Of all history! About flying! And there was no stopping her. Rainbow knew that once Twilight got on the rails, there was nothing that could be done. So there she sat, looking up at the purple mare she called a friend. And she was almost unable to admit it herself, but she had developed other feelings for the librarian some time ago.

“Air density is simply the mass of air per unit volume. For our purposes we will use kilograms per meter cubed. As altitude climbs higher, the density of air decreases. With less air molecules to push off of or flow over the wing, less Lift can be generated. It would take more speed for a pegasus to maintain the same flight, requiring more power from their wings.”

Though there was something interesting about this kind of ‘scientific limit’ of a pegasus. All these numbers and letters were staring at Rainbow, judging her abilities from some ivory tower! Twilight spoke so confidently, as if she knew flying better than Rainbow did. Flight school taught the basics, sure, but they certainly didn’t go through all these mathematics. Those old egghead mathematicians had already figured this stuff out ages ago, so why did anyone need to know any better?

“The propulsive power of the wings produces thrust. This thrust is negatively variable with altitude, meaning that the same flap high up in the air will produce less thrust than a flap near the ground. With the pegasus unable to produce enough propulsive thrust they will reach a height at which they will start to drop from no matter how hard they flap! So the pegasus with the most power available to their wings will set the record for the absolute ceiling of pegasi!”

And why did Rainbow stay? She would normally groan and whine her way out of these lectures, sometimes tip-toeing away as the purple unicorn, sorry, Alicorn would stay on the rails for hours. Rainbow knew in her heart that her feelings for this egghead were true, it just took a long time to realize those feelings.

She thinks it started sometime after Twilight’s coronation. Twilight needed a flight instructor ASAP, and Rainbow stepped right up to the job. The two of them spent a lot of time together, starting Twilight off with simple wing flapping exercises. For an egghead who struggled in PE as a kid she proved to be a quick learner in every field. It was certain that running around during all the crazy adventures they were on really helped her with cardio at the very least. Spending so much time around Scootaloo really honed in Rainbow’s teaching skills, allowing her to be more patient and get frustrated less easily. Still, it was hard to not be hard on Twilight! Pegasi were always born into their wings, having the instinct and drive to fly before they can even walk straight. Rainbow couldn’t help but feel that Twilight had gotten ahold of something she woefully misunderstood. Wings were not just a utility, but a lifestyle! Thankfully, the new alicorn was very attentive when it came to learning of Pegasi culture rather than just scoffing at it. And that was something Rainbow could hold onto, having spent much time around much less appreciative earth ponies and unicorns.

Over a couple of months Rainbow saw something change in the former unicorn. It was as if some of her youth was drained away, leaving a more experienced mare in its place. Rainbow felt more authoritative respect towards her friend, who was able to overcome the first struggles of politics. While the unicorn never lost her drive to read books at a seemingly-unhealthy rate, she was branching out from being a reclusive librarian. She was coming out of her shell more and more as she met new ponies, spending more time with her friends and really developing into something greater than her young self was.

Rainbow remembers the first time Twilight showed a true love for flying. That must have been the moment her feelings were realized. It was just a couple months back when Twilight flew up to her house in the sky. Rainbow had always knocked at the tree door and later waltzed into the castle, except for the occasional time she threw pebbles at Twilight’s bedroom window. Twilight would always come to her groaning with bedhead and bags in her eyes. So it was a surprise when Rainbow woke up to pebbles being thrown through her window, slowly sinking through her cloud home and thumping on the ground below. This time it was Rainbow who opened the door with a bedhead and a groan. What she saw on the other side was a hovering purple alicorn asking if the pegasus wanted to come with her to an early morning fly. It was during that morning that Rainbow could see how much Twilight really enjoyed, clearly pushing past how much of a workout it could be. That was the first time Rainbow saw Twilight more…elevated? It was as if the former unicorn had molted into a pegasus, character and all. And that was when the feeling sparked.

Back to the present, Rainbow could see Twilight erasing the board of all the equations she missed, about to write even more. It was frustrating! Watching the alicorn turn flying, a natural instinct, into all this science and math stuff! With a groan the cyan pegasus interrupted, standing up. “Come on Twilight, enough of this!” She stomped up to Twilight before she had much time to react, sweeping her off her hooves and bursting right out an open window.

Once the castle shrank smaller in view, Twilight poked her in the cheek. “...bow. Rainbow!!” Rainbow looked down to the blushing mare being quite literally whisked off her hooves and carried princess-style in the air. She stopped zooming higher in the sky, instead tossing the purple mare to yelp and flap on her own in the air. Twilight extended her arms in annoyance. “What was that all about?!”

Rainbow put her hooves to her own head and grunted. “It’s all that science crap we just went through! I know how important science and math is to you but it will only take you so far! You can’t know exactly how much thrust every single feather from each flap will produce! It would take way too many assumptions, like keeping the wing as straight as possible, keeping the legs splayed out to maximize stability while also being as aerodynamic as possible!”

Twilight extends her arms up towards the night sky in protest. “What are we going to do then? Get a six thousand meter-long tape measure and just fly it up until you can’t any more? Come on Rainbow, mathematics is just as important as testing. You know that! We don’t even have the right equipment right now. The air’s so thin up there it will be impossible to brea-”

Rainbow huffs and rockets up towards the moon, the rock in space that had been daring any pegasus to fly up to it since the dawn of flight. The pegasus had definitely reached her cognitive limit, acting instead of thinking. Twilight could only hear a fading “I’LL Show yooouuuuuu….” as she watched the pegasus shoot up into the clear night sky. “Rainbooooooow!”

The wind rushed past Rainbow’s face as she grit her teeth, flying higher and higher into the air. She didn’t even know how high it was at this point! She just flapped as hard and as fast as she could for minutes on end. Her hooves pointed right towards that accursed moon, hoping to show Twilight that Rainbow could commandeer the night sky better than numbers ever could. It was a birthright, not an academic paper!

The air felt colder as Rainbow climbed higher still, making her soft splayed-back fur stand on their ends. She flapped past the shivers as the temperature continued to drop and past the aches in her muscles. She then started to climb slower and slower at a noticeable pace, the moon staring at her from as far away as it had before just minutes ago. Rainbow’s vision formed spots that grew larger and larger, going unnoticed until her vision tunneled. She didn’t even realize she wasn’t breathing until her hooves fell and her wings stopped flapping. The cyan pegasus then finally reached some pinnacle to this path, falling from the moon’s mocking gaze.

Pinkie Pie bounded up to her bedroom door and opened it wide, immediately wrapping the pony on the other side into a rib-crushing embrace. “Rainbow! It’s soooooo good to see you! I had no idea you were coming to my room because usually I’m downstairs at the counter and there’s customers that need my attention so it’s hard to talk to you and other customers at the same time and…”

Rainbow’s shoulders were squeezed up towards her neck as she croaked out “Pinkie….Pink…Pinkie…let go…” She sucked in a big breath as soon as she was allowed to crumple to the floor, huffing heavily as Pinkie went on at a rapid pace. Rainbow stumbled to her feet and pushed Pinkie into the door before shutting it behind them, pushing a hoof over the pink pony’s mouth. “Shhhhh….”

“Hm? Rnnnbrrr?” Pinkie Pie’s mouth contorted against the pegasus’s hoof.

Rainbow Dash stood a little taller once she got her bearings back. “Look, it’s only for a minute okay? No one can know I was here for a…” she eyed Pinkie Pie very carefully with a raised eyebrow. “...Super Duper Best House on the Block because They Don’t Peddle Small Candies on Nightmare Night, Instead Handing Out Candy Bar-Sized Candies Secret.” Any protests Pinkie Pie had against the impromptu muffling quickly seized. She just gave Rainbow a single knowing nod, sitting her plot down on the floor. She raised a hoof to her lips, sliding it across to signal that she could keep her mouth zipped.

Rainbow nodded back, then looked away and sighed. She walked up to the window to watch the snow outside. Ponies always looked out windows longingly when they were about to say something that had…emotions in them.

“I love Twilight.”

Pinkie Pie squealed from behind her shut lips, rolling on the floor and kicking her back hooves as her front ones just barely kept the dam at her lips from bursting.

“I love her and I don’t know what to do.” She grazed her hoof on the window as…thinkers do. “I can’t put my hoof on what changed in me, but I just need help telling her. I’m recruiting you to help me. Do you think you can handle th-” As soon as Rainbow turned around she could see the pink pony laying down on one of two identical therapist couches. How did she move those chaise lounges so quietly?

Pinkie Pie stared up at Rainbow wearing thin glasses and her hair in a bun. She lay on one of the couches and gestured her hoof to the other, clipboard in hoof and quill in mouth.

A purple streak flashed across the sky to intercept a cyan mass falling straight down. A panicked Twilight was cradling Rainbow in her hooves as they impacted with a large cloud, which scooted across the sky a little more before coming to a stop. Twilight huffed with wide eyes as she looked towards the night sky in exasperation, trying to get her breath back as Rainbow stirred. The pegasus’s eyes fluttered half-open as she groaned, head rolling and hooves splayed out. “Wuh huh…”

Twilight quickly rolled over onto her side, cupping Rainbow’s cheeks in her hooves and patting them quickly. “Hey…Hey…Come on Rainbow wake up…”

Those cyan eyes stayed transfixed on her winged-friend’s face, the moon forming a halo above Twilight’s head. Rainbow smiles dreamily as she reaches out to Twilight’s face while taking labored breaths, her vision soon returning to normal. “You caught me…”

The purple alicorn gawked at that sleepy smile. “...caught you? Rainbow, I sped and crashed into you to get on this cloud! You’re so lucky you didn’t die! What were you thinking just flying up in the sky until you lost your breath?!!”

Rainbow’s head just rolled as she chuckled, taking lighter and faster breaths. With her brain getting back the right amount of that precious oxygen back she was still in a rather delirious mood. Despite the breath she gained back, Rainbow’s heart beat just as fast as it did up there. “Well…that would be your fault…since you…take my breath away…”

Twilight didn’t even hear that as she continued her tirade. She grabbed Rainbow’s shoulders and shook them. “If you listened to me you would have known that ponies need a certain air density to breathe! How high did you fly up to lose your breath? Six thousand meters? Do you have any idea how irresponsible you were? And it’s so cold! Your entire body is coated in ice!” She sniffled as she grazed her hooves over Rainbow’s chest and sides. “You did something really dangerous a-and scary and you could’ve gotten hurt! I wouldn’t know what to do without you Rainbow I-”

Twilight had gone to look up at Rainbow’s face when she saw a single red balloon float up past the cloud. It had stopped her mid-rant as she squinted, looking up to see some kind of green plant tied to the balloon by a string. She tilted her head with gears whirring before she uttered “Viscum album?” Twilight felt a pair of hooves wrap around her neck, pulling her down. Her lips were pecked at for just a moment.

“No. Mistletoe.” Rainbow smiled back at her.

Twilight’s eyes were frozen wide. Her unmoving body was keeping Rainbow warm, but that frozen stare into nothingness making the pegasus’s confidence falter. Rainbow stared into those eyes for a long time until it hurt. It hurt her heart. It hurt her very soul. What did she do? Did she just blow it? Rainbow’s heart thumped fast as her eyes looked around for an exit. Abort. Abort mission. She squirmed and struggled underneath Twilight, pushing the purple mare off of her and scrambling to her hooves to jump off the cloud. She muttered a meek “Twi I-I’m sorry…” before her hind legs kicked off the cloud to bullet straight into the night. Well, she would have. But there was a bright purple glow around the base of her wings that was stopping her.

“Come. Back.”

The cyan pegasus slowly turned her head to look behind her, eyes wide at Twilight’s annoyed and determined look. Rainbow gulped, then was slowly pulled back to the cloud.

“Pinkie, that there was a wonderful thing you pulled off.” Applejack had come behind Pinkie Pie wearing a red scarf, resting a mitt on the pink pony’s shoulder. Pinkie was busy stuffing deflated balloons and an air tank back inside of a tree just below the cloud.

Pinkie stared at Applejack for a moment in confusion before turning her head back towards the tree. She scrunched up her face and grunted as she then turned around, pressing her back up to the mountain of party supplies to use more of her weight. Applejack just smiled and gestured with her head for her struggling pink friend to move out of the way. “Lemme get that for ya.” She turned her hind legs to the tree and reared them back, kicking the supplies into the tree with a resounding “Thwump!”

Pinkie Pie looked up at the cloud and then at Applejack. “What are you doing here? I thought you had something super important to do on the farm. That’s what you told me when I invited you to Gummy’s early Hearth’s Warming Eve Eve Eve party!”

Applejack gave her a half smile with her eyes pointing up and away. Rubbing her hoof on the back of her head she went “Eheh. Yeah well. I was actually coming here to do…” She pointed towards the cloud. “...that.” Applejack reached up to pull a slip of paper out of her hat, ripping it up into little pieces. "Won't need that little speech any more."

Pinkie still looked confused, so Applejack elaborated. “About a few months ago Twilight came for a visit to the farm just as I was finishin’ up chorin’ for the day. She seemed all nervous-like, but not th’ kinda nervous like a Manticore’s behind her. We spent th’ better part of th’ evenin’ in th’ barn as she spilled her guts out about Rainbow an’ how loyal and cool an’ outta her league she is. I was surprised she didn’t come to you, but I guess she considers me to be the one who can keep her secret safe. Strange considerin’ mah track record…”

Applejack stared up at the cloud as she sat on the grass, placing her Stetson hat onto a nearby rock. Pinkie Pie joined her, throwing a large pink blanket over them both to keep the cold winds from chilling them to the bone.

Pinkie Pie, shivered for a moment until their shared body heat warmed them both up. She smiled to Applejack and patted her golden mane. “And how’d the scheming go between the two most honest ponies in Ponyville?”

Applejack smiled as she playfully bat Pinkie’s hooves from her face. “Ha! That was simple! I told her to really buckle down in whatever RD likes th’ most. It seemed she chose right, seeing as how it helped ‘em both spend more time together.” She pointed towards the cloud. “That cloud’s still as a fence on the farm. Seein’ as how Rainbow an’ Twilight are still up there, I bet they’re workin’ things out.”

Pinkie smiled wide at Applejack the more she spoke. “AJ!! That was the bestest thing to say!” Applejack shushed her to keep the two fliers from hearing their own help down below. Speaking in a lower whisper, Pinkie Pie went on. “Rainbow Dash came to my room one day and we talked allllll about her feelings. I can’t say much since was a Super Duper Best House on the Block because They Don’t Peddle Small Candies on Nightmare Night, Instead Handing Out Candy Bar-Sized Candies Secret, but I can tell you that RD appreciated that the most from Twi, without breaking confidentiality laws of course!”

Applejack blushed softly as she moved to hide under her Stetson hat, her hoof only holding air. “Aw shucks…”

Twilight’s stare could have been one to rival Fluttershy’s in the bone chilling sense. If Rainbow wasn’t already shivering from the ice that formed on her fur, she was shivering now. Twilight gently set her down on the cloud and stepped up to her, pushing a hoof into the pegasus’s chest. “I’m going to talk and then you’re going to talk.” Rainbow nodded in silence and a little bit of fear.

Twilight put a hoof to her chest with a big breath and closed her eyes, extending her hoof out with an exhale. “You…scared me tonight. You went up there…and then fell back down.” There was a little trembling in her voice, yet she held her composure. “I really…did not like it when you fell down.”

Rainbow stepped forward with a concerned look. “Twi you don’t have to dumb it-”

“Shh. I’m talking.” Rainbow slumped and looked to the floor. “Rainbow. I cannot imagine a timeline in which you are not in my life. You have been loyal to me just as much as everyone else. I can tell you care about anybody. But…” Twilight took a step forward and lifted Rainbow’s chin. “I want us to care for each other…I want…you. I just need you to talk to me straight.” Those words lingered for a moment in the cool air. Twilight’s hoof felt warm to its touch. Their manes billowed in the chilling breeze.

Rainbow stared into Twilight’s eyes for a long while. She knew she was on thin ice colder than the wind. As the words lingered she knew it was her turn to speak. She gave Twilight a very understanding and slow nod before speaking up. “Twilight. I am not all that great at mushy lovey stuff…” Her voice cracked and forced her to clear her throat. “...but I wanted to tell you that you’re really…awesome. I knew you as this really young egghead who ducked away from any social contact to shove your nose in your books. I then knew you as the brave unicorn who fought battles with crazy bugs and leaders. And then when your wings came…” Rainbow dug into the cloud in circles. “...I was stunned. The way you handled everything. You were entirely respectful to the culture of pegasi. I know that wings might seem like a utility at first but…they really are a state of mind. Ironically, learning to fly up high really got that thick head out of the clouds.” The pegasus looked up with a more confident smile, taking a Twilight’s hoof in hers. “You’re a lot more experienced than the day I met you, and I’m going to need that when being the best flier in Equestria doesn’t cut it. From the moment I met you to the moment I saw you truly enjoy flight.”

Twilight’s eyes were wider now that she bore a more caring smile. The coldness from her stare was gone, replaced with warm sweetness. They both shared a moment looking into each other's eyes before Rainbow Dash went in for the kill.

“Whatever caused our fates to intertwine would never let them unravel.”

The purple mare couldn’t take it any more, practically jumping on top of the pegasus with gleeful laughter. She wrestled her pegasus partner to the cloud and hugged her tight while they both laughed together

“It’s been an hour. How much longer are those two going to be up there?” Pinkie Pie groaned and hugged at the pink blanket. Applejack blinked as she looked up at the cloud, which seemed to have a little activity going on.

She coughed into her hoof and stood up from the blanket. “Come on Pinkie. Let’s git.”

Author's Note

I am now far too interested in the flight dynamics of pegasi and I am sorry to bore everyone with this information. This all comes from a 400-level aerospace course I took this semester. The second chapter of my book was used to create the sciency (super boring) parts of this fic.

Pamadi, B., 2004. Performance; Stability Dynamics; and Control of Airplanes; Second Edition. 2nd ed. Blacksburg: AIAA.

Easter egg: Find the Fallout 4 quote.