"Well, it's been years since we've made any real innovation." Harry says as he sits with Hermione in the Great Griffin's workshop.
"I know! Who knew traveling the world took up so much time?" Hermione says with some irritation.
"Why don't we think of something new, perhaps a way to increase speed? The Americans would love that. Ron says his waiting list a year long already." Harry suggests.
"Ron has really flourished in America hasn't he? Putting him in charge of our New Jersey manufacturing operation was a great choice." Hermione says.
"I think he only tries so hard so he can afford more food." Harry says.
"At least the waiting list is longer than his usual fast food order now." Hermoine says with a laugh. "Anyway, the only way we can increase our speed is to mimic a jet engine."
"That sounds like a problem." Harry says with worry.
"It is. Since we don't use a fuel source now we can't use one for this other than magic." Hermione says.
"Let's start with the basics. A jet works by forcing air down a tube right?" Harry asks.
"Basically yes. Fuel is mixed with air and burned, the expansion caused by all this heat forces air out the back of a jet." Hermione explains.
"And we can't do that, heating charms simply aren't strong enough. A normal magic user would just create fire to get more heat and that requires fuel as pure magic isn't efficient at all. Or controllable in the case of fiendfyre." Harry analyses.
"And we can't conjure air to create pressure since conjugation is not magically efficient enough." Hermione adds.
"What about mimicking the turbojets from modern aircraft?" Harry suggests.
"A shrouded propeller could help, since we could then increase the rotation beyond the speed of sound without the negatives of doing that to an exposed prop. But in the end the thrust wouldn't be worth the extra size and weight." Hermione says.
"So we need to think outside the box." Harry says, and the two of them sit and think for a moment.
"Hermione, what about extension charms?" Harry asks.
"We can't put a huge propeller in a small box, the charm only works with one entrance and exit." Hermione answers.
"Not that, how does air fit in those bags when they are made? I don't remember hearing a loud sucking sound." Harry asks.
"It just exists Harry, now let's get back on topic." Hermione says with slight irritation towards their digression.
"But when the charm fails air explodes everywhere along with anything in the bag of course." Harry says.
"You know this Harry." Hermione says.
"So it creates a lot of air but doesn't vanish it afterward." Harry says thoughtfully.
"Yes Harry, now let's move on... wait! I see what you're thinking!" Hermione shouts as Harry's idea finally filters through. "Oh we are going to have to visit the man who makes wizard trunks and bags!"
"So it could work?" Harry asks.
"It should! It doesn't take anywhere near as much magic to make those bags as it does to conjure air. If we could miniaturize it and create dozens in one tube, we could have thrust!" Hermione cheers.
Suddenly the mirror buzzed and they were drawn from their excitement.
"Hello?" Harry asks.
"Oh Harry! It's terrible! Ron and Seamus's new aircraft crashed!" Ginny shouts in near tears.
"How? They are both decent pilots. What happened?" Hermione asks.
"The magic ran out and the engines failed." Ginny says.
"That should still be fine, planes can glide." Harry says.
"Weren't they working with helicopters?" Hermione questions.
"Still should autorotate safely to the ground." Harry says.
"They had this new plane! It's both a normal plane and a helicopter, based on the new American marine Osprey." Ginny says with tears on her face.
"I see, we will hurry to the hospital. Where are they?" Harry asks with sudden understanding.
"St Mungo's, they were testing out of your airstrip." Ginny says before cutting off the mirror call.
"I don't understand? What's wrong with the Osprey?" Hermione asks.
"It's a small cargo plane that can land and take off like a helicopter but flies like a plane." Harry explains.
"How could that be so bad you knew right away?" Hermione asks. "The harrier works fine."
"You really need to stop your British tunnel vision." Harry says with a sigh. "The Osprey is in an unfortunate gap where its wings are too short to glide and it's not stable enough to autorotate."
"Why would anyone design something like that?" Hermione asks.
"Who knows? It's the US Marines, maybe they see it as an acceptable risk." Harry theories as they begin climbing to the cockpit.
"From your face I'm guessing there is more wrong with this plane." Hermione says stoically.
"More that you would ever believe." Harry says.
"Well we have a long flight." Hermione says, "Might as well get started."
"Well, I'll start with how its down draft is too strong for carrier decks, parachuting safely or for anything to be remotely near it."
"I see." Hermione says.
A few long months later, Harry and Hermione are at their airstrip with the freshly released Ron and Seamus.
"To celebrate your release from St. Mungos, Hermione and I have built you a new plane to try out!" Harry says with cheer.
"It's unlike anything we've built before." Hermione adds as Harry waves his wand to remove the cloth cover.
"Oi Harry. Mate, you forgot to put the propellers on." Ron says once he gives the plane a quick glance.
"This plane doesn't need propellers." Harry explains.
"If you say so." Ron answers with trepidation, "It is very smooth, does it go fast?"
"Does it? It is the fastest plane we've built." Harry says.
"I'm still going to decline flying it. I think my testing days are over." Ron says.
"Your choice." Harry says, jumping into the cockpit. "I'll give it a spin and you can see what you think."
A few moments later the aircraft roars into the sky and a few moments after that everyone follows in a special B-25 medium bomber designed for data collection and observation.
"What is it anyway?" Ron asks as he resists the temptation to glue his head to the window like a child as the prototype plane races by.
"It's a jet fighter based on the German Me- 262." Hermione explains as she checks that the sensors are working.
"How does this jet work?" Seamus asks.
"A Jet engine takes in outside air and compresses it before sending it out the back at high speed to create thrust." Hermione explains.
"How does that work with Magic?" Ron asks.
"We use a manufacturing ruin set for extension charmed bags and a canceling enchantment." Hermione begins. "Inside the engine there are many nozzles with leather flaps on the ends, they are turned into extended containers then canceled. Somehow this more efficiently generates air than conjuration; and so we have a source of pressure. With enough nozzles we can even out the flow and make it smooth thrust."
"I didn't understand any of that." Seamus says, looking at Ron who was less confused but still out of his depth.
"Don't worry, you will get our notes. It's rather simple and we kept it to only one thousand pages." Hermione says cheerfully.
Now not even the extreme speed and insane maneuvers of the new plane could lift their spirits.
"Anyway, we will leave figuring out manufacturing to you and the Twins, Harry and I have bigger plans." Hermione says after a moment.
"What are you trying now?" Ron asks nervously.
"Nothing much, just going to make the first magical plane to go faster than sound consistently." Hermione explains.
"Like when Harry played the best game in Cannons history?" Ron asks.
"Yes." Hermione replies, voice suddenly strained with irritation from that memory. "But controlled."
It would of course be noted that Ron had a terrible accident when he attempted to fly the new jet a week later, he over worked the throttle and ruined the engines compression. Luckily he was only in St. Mungos for a weekend this time.
AN: I've spent a lot of time considering how a jet would work with magic and this is the most interesting and close to cannon magic I can do. And don't expect turboprops, the enchanted spinning already does that better than anything.
And no this story isn't Alive or Dead, it just is. I write when I have ideas and when they work out, I still have ideas for this but I am missing plot so you know, expect something within a year or so.