I was inspired by the series, Youjo Senki/The Saga of Tanya the Evil to create a class to represent the Imperial flight mages.
It follows the idea of a war mage who is an aerial combatant, using magic and altitude to dominate the battlefield. They seem to be a cross between an Arcane Archer and a Wizard/Sorcerer, using magically charged rounds to inflict damage and spells to protect themselves and remain airbourne. If I were to play one in vanilla D&D, I would either go for an Eldritch Knight archer, or take five levels in Wizard/Sorcerer to gain Shield, Fly and Mage Armor, while multiclassing into an Arcane Archer.
That said, neither of these works in early game; Eldritch Knights don't get Fly until level 14, and the multiclass doesn't come into play until level 8.
So, we want a class that can put out magical attacks, and fly at earlier levels. Having fly before 5th level would be a significant boon; it's a 3rd level spell. On the other hand, the Aarakocra gets it at a creation as a racial feature, with a faster fly speed of 50 ft., over fly's 30, at a cost of 5 ft. slower walk speed (and no other fancy racial features).
The characters in the series gain access to a wide range of spells, so a Wizard will be the best base for this archetype.
Flight Mage Tradition
War Mage
At 2nd level, when you choose this arcane tradition, you gain proficiency in martial weapons. Additionally, you may use your martial weapon as a spellcasting focus. You may also use a hand that is wielding a martial weapon to fulfil the somatic component of spells you cast. When you take this arcane tradition, you gain an additional 2 hit points, and another 1 each time you gain a Wizard level.
Imbued Rounds
At 2nd level, at the end of a short or long rest, you may imbue your ammunition with magic. Expend a spell slot of any level for each round you wish to imbue. Add your proficiency modifier to attack rolls when using Imbued Rounds. If an attack with one of these rounds hits a target, it deals additional force damage equal to 2d6 for each level of the spell slot expended.
You do not recover spell slots expended this way at the end of a long rest until either the imbued round is expended, or you choose to end the effect on that round.
Close Air Support
At 6th level, your Fly spells no longer require concentration if you are the only target of them.
You may also imbue your ammunition with explosive force. When you imbue a round of ammunition using your Imbued Rounds feature, you may additionally imbue it with a 1st level spell slot to make the round explode. A shot fired with one of these rounds does not roll to hit; instead, each creature within 20 ft. of a point within your weapon's range must make a Dexterity saving throw against your spellcasting DC. On a failure, they take damage as per the Imbued Rounds feature, and half as much on a success.
Expending a 2nd level spell slot instead of a 1st level spell slot increases the area of effect to 30 ft instead of 20 ft.
Extra Attack
At 10th level, when you take the attack action on your turn, you may make two attacks instead of one. You also ignore the loading property of weapons you are proficient in.
Annihilation
At 14th level, your spells blow away all resistance; there is nowhere for your enemies to hide. Attacks made with your Imbued Rounds now deal twice as much damage. If a creature fails a Dexterity saving throw against one of your Imbued Rounds, they now take double damage on a failure, and normal damage on a success.