[quote=@Cyclone]
[@Willy Vereb]

Pfft, anything is better than nothing and the Sultanate doesn't have much capacity to make their own planes. If given enough money I'm sure elves could modify their designs to be more friendly for humans.

But if you insist maybe I could try buying aircraft from Ventium.
[/quote]Ventium is closer and while their designs are a bit crazy they are sure kinder for human pilots.
Elves can indeed build you aircrafts but their designs mostly work because of their natural capabilities and the properties of mithril.
Mithril would cost a lot and you'd be basically buying metric tons of them accompanied with their aircraft technology. Some aircrafts are also in such a compact size you'd be hardpressed to instant aviation gear on them.
You can ask the elves to use steel, plywood and other typical design elements for aircraft but the manufacturing of these will be subpar compared to what nations who already have more experience with this would do.
Really, Yllendthyr has only basic knowledge on steel since they kept relying on mithril.

Long story short you can ask them but I'm sure there are tons of better candidates.
You have a better shot at hiring some mercenaries from Yllendthyr and work for your army.
There are always some nobles down in the slums and in need of money. Hiring their private air squadron could be a rather valid solution, even if won't give you a really big force to work with.