IS there any large flying mechs i can get without UC or shop?

I really want to try out my 2 stardust cannons, but working to use the king mountain mech is far off for me, and i dont have the means to buy RTs. so i was wondering is there a Large flying mech i can assemble from either questing or pvp?

Nope. You Either do Garapon or Buy them from the Shop. That's it.

Well, there's a shitty Tengu for 17k UC.
Very bad core and parts, poor performance. Still it's your only choice if you want to try SDCs.

I use Tengu+ stardust + shield. change the parts (I use Goblin HD n Seraph Crim LG) to increase TEC and FLY. It is quite decent to damage LND unit (40+ dmg + splash). If you decide to try Tengu and SDC, I advice don't rush too much to frontline. Tengu are big and slow + low TGH that any ART can easily kill Tengu. Furthermore, avoid being alone. SDC's DPS is not that great. Its strength lies in the splash radius(eat that Jikuns) and its long range. An AIR unit will easily outmanuever and outperform a Tengu equipped with only SDCs. Personally, I play him like an airborne artillery unit that is great against LND.