It had been a quick five years since Voldemort's defeat at the hands of the ministry's aurors. Harry and Hermione had spent most of it working on aircraft. The twins had even tried selling them in their shop, but Magical Britain was too conservative to even consider buying. They were lucky just to keep them legal after the broom companies lobbied to ban them just like flying carpets. With this dire outlook Harry and Hermione began work on their masterpiece, the flying yacht, Great Griffin. A truly massive flying home, with a 150 meter wingspan and a 95 meter length the two and a half story home contained everything anyone could need to live a comfortable life. 14 magic engines were needed to bring the beast into the air. Six pulling engines on the wings with six pushing behind them, another two engines were mounted in a pushing configuration on the tail. Harry's favorite feature took up the entire rear half of the plane, a special catapult for his original aircraft. Which had been modified with a set of floats for short distance trips.
Of course there was no way to hide this beast from the normal government and as such Harry had to get a pilot's license. He had a quiet friendly instructor named Nigel Westwood who said he had recently retired from the RAF after an incident with a biplane. Harry swore to never mention it was him.
On their first major flight they went to the Bahamas and when several wealthy yacht owners saw the majestic flying yacht they raced over to ask where they could buy one. Unfortunately they couldn't sell their design since it required magic, but they did end up working with a private jet company and a yacht company to design a normal version.
The defeat of Voldemort had unfortunately cemented Fudge's regime and Sirius was unable to gain a trial, so he fled to Ecuador, which gave him a trial and asylum. As a gift for his freedom Harry and Hermione built him a small four engine flying bachelor pad which he enjoyed immensely, and enjoyed showing off to any South American girl that he could find.
"Well, it's time to start our new life." Harry says as he stands on the edge of Hogwarts lake after his wedding to Hermione.
"We have two weeks before we need to meet my parents in Monaco, Let's start heading west and we'll go around the world." Hermione says.
"Then we have no time to lose!" Harry shouts, picking Hermione up and racing off to the Great Griffin.
Soon they were circling over the reception on the Hogwarts lawn. The silent giant escorted by the herd of thestrals.
"It's nice to have them see us off, isn't it." Luna says from behind the pair.
"Luna!?" Hermione shouts.
"Yes?" Luna answers, turning toward Hermione.
"This is our honeymoon." Hermione says.
"It is." Luna answers tilting her head to the side.
"What are you doing here?" Hermione asks.
"The nargles said I would find a crumple-horned snorkack if I came with you." Luna answered with the tone of someone stating the obvious.
"I see." Hermione answered.
"The more the merrier I guess." Harry says as he guns the engines and tries to pull a loop.
"HARRY!" Hermione screams, forgetting about Luna as the massive plane groans with effort.
Fred and George would swear they heard Harry's laugh from the ground as the stunned reception watched a plane that couldn't fit in a quidditch pitch fly like a kid on a broomstick.
AN: a quick epilogue for this story, I might add some AU shorts after this (with all kinds of planes), but I wanted to end it as properly as I could. And yes the Great Griffin would break all kinds of records if it existed...