If this WebGL doesn't run smoothly for you, you can try downloading the standlone build to your computer from my GitHub page:
https://github.com/OuterGazer/Skies-Over-Norville-Valley/raw/master/Skies%20Over%20Norville%20Valley.zip

Move aircraft with WASD or arrow keys.
Shoot machine gun with left click or spacebar.
Drop bombs with left click or any alt/shift key.
Disable/enable crosshair with C.
Pause with P and quit with Esc.

Shooting increases the machine gun's temperature. If it goes too hot, it will get stuck until it cools off. However, overheated bullets deal double damage.
The aircraft repairs itself over time after a certain amount of time has passed without getting hit.