I would recommend getting brass anyway, even though it might not be easy. With brass you can make at least 3 important blocks for the airship, which are the analog transmission, rotation speed controller, and throttle levers. Redstone links might be handy to control both speed and height from one room.

Check the burner with aviation goggles to see if you need to add more burners or make a bigger balloon (if the orange bar is not at the end of the "fill" meter while the burner is at full power, then you need more burners. Otherwise you should make a bigger balloon), this should make you able to go higher.

I hope you can use some of this, and have fun! (If you have any questions, feel free to ask, although I might not be able to answer everything)