Measuring Deegrees.
I think this will help players make the artillery like IRL.
I have 2 solutions:
1. Make the display link measure degrees. It will be attached on Cannon Mount and Yaw Controller. (Simplier)

2. Make the new block like stressometer and speedometer, that will aslo be measured by display link, It will measure not just cannon position, but all Create Contraptions. (Harder)

But there is a problem: -Developers of Create: Aeronautics can make protractor block too. But if they wouldn't make it, and you make it, i suppose more people would download your mod because of that (sorry, i didn't mean to say that protractors better than your mod).
/
And the last thing: -Artillery Compass. It would be like regular compass IRL, but it will show you degrees where you look at. Like when you look at north-east it will say: North-East 135°
I think it would made of compass and precision mechanism, and looks loke golden compass (or at least with golden crops on its texture)

if the mod worked it would be great, but I'm uncertain the mod works right now.

e05738f

Finally implemented it here.