In the week following the drive test that had proven that earth ponies could power a thruster, the two friends had taken over one of the outbuildings of Sweet Apple Acres, and had moved all of their equipment to it. After the massive jet of flame the drive test had created, Granny Smith had insisted Applejack and Rainbow Dash move their work to a less...frequented area of the farm. To that end, all of their gear and equipment had been moved over to the new building. Over which Rainbow had proudly put up a sign saying, "Apple Aerospace."
"So, RD," said Applejack. "Or should Ah call you RA now, Rainbow Apple?"
"Ha ha," said Rainbow Dash. "Very funny. I respect Granny way too much to argue with her about her calling me an Apple. I mean, she's letting us use this building and she even gave you the week off. She's pretty awesome."
"Speaking of Granny," said Applejack. "Did you manage to get that other unit back from her?"
"Yah," said Rainbow Dash, colouring slightly. "She gave it back to me, yesterday. Said something about 'new-fangled plows' when she did."
"So, RD," said Applejack, with a slight chuckle. "We've been working on stuff all week now. What's the plan?"
"Okay, Applejack," said Rainbow Dash, as spread out a somewhat crude diagram. "We've reshaped the test frame harness so it will fit you better, and we've made one, just as solid, for me. The harnesses each have a spar running along their length. Yours is along the back and mine is along my belly. The spars lock together, making you and me a single flight element -"
"Um, Rainbow," interjected Applejack. "We already have Granny thinking we are some kinda kinky bondage couple. Ah mean, Ah like you and all, and maybe we will have a little fun if things go right. But we do this and everypony, and Ah do mean everypony, is gonna assume we are together."
"Ya, about that," said Rainbow Dash, as she reached a wing into a nearby bag and pulled out a bridle with fairly large bit attached to it.
"What. The buck. Is that?" demanded Applejack.
"Ah, well, I thought you would want direct control of your thruster," said Rainbow Dash. "The bit is a throttle control. The bridle will keep it in place, so all you have to do is to roll the bit in your teeth, and you can set the thruster output to whatever you like."
"Dash. It's a bit. And a bridle," said Applejack, with more than a little bite in her words. "And where did you even get that?"
"Well…." said Rainbow Dash, who sighed and then pressed on. "Granny told Big Mac about us, and he told Fluttershy, and she told Twilight. So, when I went to Twilight to get something so you could have more control…she already had that waiting for me. And one for me too. Don't forget, Twilight has been tweaking these things for awhile now, so I'm guessing she was planning for these to go with the new Mark III unit."
"So, everypony already figures we're together. Well, as long as you got a bridle too," said Applejack, who shook her head and then smiled. "If everypony is figuring we're a couple now, we might as well match. C'mon, we better make sure they fit." With that Rainbow Dash fitted the bit and bridle to her friend and Applejack did the same to Rainbow Dash. Both fit perfectly. The bits attached to the bridles were not pulled to the back of the mouth as expected, but instead, sat in the middle area of the mouth. This made them relatively easy to speak around. As well, what had first been taken for as reins were actually the control runs from the bridle to the thruster unit.
"You know, Dash," said Applejack, around her throttle bit. "You actually look kinda good yourself, wearing a bridle. Sort of a controlled strength sort of look. Looks good on ya." Rainbow Dash blushed a bit at the unexpected compliment. "So, we good to go for tonight?"
"Ya," said Rainbow Dash, accepting the change of topic. "Big Mac will be here just after dinner to help us harness urk—" Rainbow's words were cut off as Applejack grabbed the control runs, and using them like the reins they resembled, took control of the bridle and bit in Rainbow's mouth.
"Ah still owe you for all that stuff you did, when you had me bolted into that metal harness the first time," whispered Applejack into Rainbow Dash's ear. "And there are hours until Big Mac gets here. Time to see just how awesome you are." With that, she pulled her willing mare friend toward the nest of cushions they kept in the back of the building for naps.
-==========00000==========-
Hours later, after the sun had set, Big Mac was tightening the final bolts that secured Rainbow "Apple" into her harness. "So, why you all doing this at night?" the roan stallion asked.
"I want everypony to see how awesome your sister is," said Rainbow, as Applejack grinned. "Seriously, I can't believe how much power she was able to give to a thruster unit. And the flame! That was totally cool."
"Don't worry none about the orchard, Mac," said Applejack. "The plan is for Rainbow to use her unit to get us up into the air. Once we are high enough above the trees, Ah'll fire up my unit and well, we blast off."
"So that's why you had me make an oversized scooter and a jump ramp," said Big Mac.
"Sure is," said Rainbow Dash. "At the start, I'm going to be flying us both, so the scooter and jump ramp will be a big help. Plus, it will look awesome." Dash did a few tugs and pulls on her harness. It wasn't going to come off on its own any more than Applejack's was. "Okay, Applejack, time to see if you can fly."
With that Applejack stood on the scooter and braced herself. Then, using a small stool, Rainbow Dash climbed up on top of her friend. Moving carefully, she matched tabs in her harness to slots in Applejack's. Once they met and seated, Big Mac moved in and bolted the two harnesses together. For better or worse, Applejack and Rainbow Dash were now a single piece of steel, flesh and fur.
"All secure?" asked Big Mac.
"Yup," said Applejack and Rainbow Dash at the same time.
"Okay, Big Mac," said Rainbow Dash. "You get to have some fun now."
"Eyup," said Big Mac in an oddly pensive voice. Big Mac went over to a workbench and returned with a lubricated Mark II thruster. He slid it back and forth over Applejack's tailhole and pussy, getting some of the lubricant onto his sister, before sliding home the twin plugs of the Mark II.
"Ahhh," Applejack breathed out explosively. "Ah don't think Ah will ever get used to that thing going in. Hey, Mac, aren't you gonna lock it in place?
"Eyup," said Mac, as he gathered up the other thruster unit, and repeated the process of insertion on Rainbow Dash. Then, to both mares surprise, instead of securing the thruster units, Big Mac began to work the double prongs of the two units in and out of the harnessed duo. Applejack and Rainbow Dash both began to moan and shudder as the collector shafts of the thrusters slid in and out of their intimate passages.
"M-Mac, what are you doing?" asked Rainbow Dash desperately. The stimulation Big Mac was working on her was swiftly building her to climax. She could feel that delicious heat building inside her and she knew Applejack had to be feeling the same. "You've g-got to s-s-stop."
"And why would Ah want to do that?" asked Big Mac seriously. "Seems to me that, if Ah get either of you to come, y'all can't go off on this dang fool thing and get mah sister's neck broke."
"M-Mac, please," begged Applejack, her own voice trembling with her nearness to orgasm. "Let me have my dream. Let me fly." Big Mac looked at his sister and nodded.
"You promise me, Dash," said Big Mac, suddenly stopping his attempt to drive both mares to orgasm. "You promise me, that no matter what, mah sister makes it back. Safe and sound. If you can't do that, Ah'll have to stop you." He tapped Dash's thruster to emphasize his point.
"I swear, Mac," said Rainbow Dash. "If Applejack doesn't make it home it will be because I'm already dead and gone. She makes it home, no matter what. I swear it."
"Good enough," said Mac, pressing the button on both thrusters that caused them to lock onto both mares. The harness modifications also meant that the thrusters attached to their harnesses as well, making the two brave mares into a single, double-driven unit.
"Thanks, Mac," said Applejack. "Ah know you worry about me, but this is something I need to do."
"Ah'm sorry, AJ," said Big Mac, as he began to wheel the pair out to the runway they had prepared. "Ah don't think Ah could stand losing you."
"It'll be okay, Mac," said Applejack. "Ah've even got a parachute in this rig just in case everything goes pear shaped. Now, go get clear and send a message to Twi letting her know we are getting ready to launch." Big Mac said nothing, merely nodding as he finished positioning the modified scooter carrying Applejack and Rainbow Dash at the end of the long straight stretch that ended at a jump ramp.
Big Mac put a forehoof on Applejack's shoulder and said, "Fly safe, both of you." Then he scrambled off to the side.
"Okay, Applejack," said Rainbow Dash. "You ready?
"Let's go already," said Applejack with a grin.
"All right, AJ. Just like we planned," said Rainbow Dash. "I'll get us up to a few hundred feet, and when I put us into a second climb, you light off your unit and we see what happens." Rainbow Dash took the bit in her mouth and triggered her thruster, its power driving the linked duo down the runway. As acceleration took hold, the wheels on the scooter turned faster and faster, and as their squealing cry and that of the thruster rose to a banshee wail, the intrepid duo reached the launch ramp.
As they were hurtled into the air Rainbow Dash extended her wings, letting out a grunt of effort as her frame took up the combined weight of both ponies. The blue pegasus kept their flight as smooth and even as she could, slowly climbing in a classic "racetrack" pattern in order to stay over the farm. After a couple of minutes, Rainbow Dash pushed her control bit out to talk to her friend beneath her.
"Okay, Applejack," she said. "You ready?"
"Ah've been ready for this all my life," said Applejack. "Let's do this...together." With that, she drew her own control bit into her mouth.
"Together," said Rainbow Dash, and as she angled her wings into a climb, she added more thruster power to maintain their attitude. Ten seconds later, Applejack activated her thruster…and all hell broke loose.
In the first few seconds, all that happened was a solid push of acceleration, as the greater power and stamina of an earth pony gave Applejack's thruster ten times the power of a pegasus driven thruster. But then Applejack's thruster interacted with Rainbow Dash's, and what would later be termed "The AppleDash Effect" manifested itself for the first time ever. It was expected that the thrusters would add their power together, but that isn't what happened. It was hoped that the thrusters would, perhaps, multiply their effects on each other. That didn't happen either.
Instead the thrusters added their power together, then that power folded back on itself, so that it multiplied itself...by itself. What was initially an extremely impressive four hundred wing power suddenly erupted into a mind-shattering, one hundred and sixty thousand wing power. Ponies suddenly looked up in astonishment and terror as a second sun suddenly dawned over Ponyville. The air was shattered by the rolling thunder of the two-hundred-foot-long jet of flame that was now strung out behind Applejack and Rainbow Dash. Against that titanic force, flesh and bone was a frail reed, and Rainbow Dash's wings were slammed against her sides.
With all aerodynamic control lost, the only guidance was provided directly by the thrusters themselves, and they continued to drive the duo upwards into what soon became a near-vertical climb. Applejack was lost to the glory of flight and the driving churn of the thruster insider her. For her part, Rainbow Dash realized the danger they were in, and used her pegasus magic to gather a bubble of air around them. She knew that at the rate they were climbing, the air would become too thin to breathe within seconds.
"Applejack!" screamed Rainbow Dash in her friend's ear, even as the sky turned black above them again. "You've got to slow down!" But Applejack didn't hear her, so lost was she in her internal world. It wasn't until thirty minutes later, as the air that Dash had trapped around them began to grow stale, that Applejack finally snapped back to reality.
"Sweet Murphy!" exclaimed Applejack, as she let off on her bit throttle and saw the very small and distant disc of Equestria. "We're higher than a kitty in the catnip. Why'd you let us get so high?"
"I didn't have a choice, Applejack," said Rainbow Dash. "I'm not sure what happened, but we went so fast I couldn't use my wings anymore. And, I think we're in real trouble."
"Why's that?"
"Because the air I pulled around us is running out," said Rainbow Dash. "And, if you haven't noticed, we've gone past the freaking moon! There's no air here. None at all. We need to get turned around, right now. But there is no air for me to push against to turn us."
"Okay, Dash," said Applejack. "Hold on. I'm gonna try something we use on the farm sometimes to get plows to turn." With that, Applejack throttled the thruster back up and began to rhythmically grunt. Rainbow suddenly realized that with every grunt Applejack made, their course shifted a few degrees. Slowly but surely the pair of pones turned around, to face their now very distant home.
"What did you do, Applejack?" asked Rainbow Dash. "That was pretty awesome."
"Pelvic floor muscles," said Applejack. "I used them to rock the thruster back and forth to get us turn, just like we rock a plow when we pull it to turn around, if it gets stuck a bit on the farm. We good now?"
"Nah, we're toast," said Rainbow Dash, despondently. "You turned us, but we are still headed away from Equestria and we've maybe got a couple of minutes of air left. Unless..." Rainbow Dash paused as she suddenly remembered her conversation with Spitfire on the very first day she had seen a thruster unit.
"Unless what, RD?"
"We've got one shot at this," said Rainbow Dash, suddenly energized. "I know you were at about eighty percent on your throttle, like me. We need to both go to full thrust and then..."
"Then, what?"
"Then we both need to come at the same time," said Dash. "The only thing that would give us a chance is what the Wonderbolts call 'flaring out.' One huge burst, to get us home."
"Okay, Dash, times a-wastin'," said Applejack, nodding. "Let's do it. 3...2...1...thruster on." With that, both mares activated their thrusters.
"AJ, go to full," grunted out Rainbow Dash a moment later, as she did her best to hold her orgasm at bay until the right moment.
"A-At full, now," gasped Applejack. "A-Ah'm close, RD. Call it out."
"R-Right," said Rainbow Dash. "O-On my call. 3...2...1...FULL THRUST!"
Both Applejack and Rainbow Dash cried out in ecstasy as they finally allowed themselves to give in to the siren song that the thruster units had been playing inside their bodies for so long. The units gleefully soaked up the surge of released lust and the duo suddenly disappeared in a coruscating rainbow, as the thrusters broke through an unknown barrier.
Elsewhere…
"Warp trace!" cried out a voice. "Warp one, unknown configuration."
"Point of origin?" asked a much calmer voice that held the tone of command.
"Two three eight, mark twelve. Distance puts it in the Epona Sector, sir," said the first voice. "Trace is gone, sir. Not much more than a warp burst."
"Right. Seems like someone out there has made a breakthrough," said the second voice. "Let's welcome them to the neighborhood. Who do we have nearby?"
"Enterprise is in area studying gaseous anomalies, sir," said the first voice. Now in a much calmer tone.
"Right, send Picard a message giving him our best idea of the location," said the commanding voice. "Tell him to prepare for a First Contact situation."
Two hours later, the search teams found Rainbow Dash and Applejack still linked together, half-asphyxiated and unconscious. Their desperate gamble had gotten them home just in time; but in the end, it was only the last minute addition of the parachute to Applejack's harness that had saved them both from a fatal impact.
"Are they going to be okay?" Twilight Sparkle asked Luna, who had spotted the falling duo and sent the rescue teams to the right area.
"I believe so," said Luna. "But one thing is certain. Those ponies have boldly gone where no pony has gone before."
