Since I updated to android 5 I noticed that the navigation bar at the bottom kinda takes up screen space.It may have been like that before but I didn't notice,now the icons are lit all the time I'm aware of it more.Done a bit hunting around and found a background app which puts your device into immersive mode and the game runs full screen which in my case is about 1cm extra in screen height.
Once in game it prevents text but you just swipe the bottom bar up to text then swipe it back down into immersive mode again do full screen.I have placed the swipe trigger to the left bottom,you see a short red line.
The app is "GMD full screen immersive mode"

Without GMD in use

With GMD immersive mode in use

Even the sight has gone more circular.You can see the difference in the fire buttons and speedo,altimeter.

I've just released an update that should hide that bar automatically.