I am working on a gun turret for a spaceship. The turret has three parts. It resembles a Gatling gun type. I have animated the barrels to start turning very rapidly to simulate rapid anti-aircraft fire. The first keyframe is set to o degrees in the rotation, I then move the keyframes 3 seconds further and then enter 5000 in the rotation. The animation starts exactly as I want but about half way, the rotation slows down and then accelerates again. It does the same thing when rendered. What causes this slowdown? Could it be the processing power of my laptop or is there a better method to use? Thank you.
This is caused by tweening. tweening defines how a object goes from one keyframe to the next. you can adjust tweening in the graph editor. in the graph editor, when you have selected the object being animated, you should see three lines. a red one, a blue one, and a green one. In this particular case, the red one is for x rotation, the green one is for y rotation, and the blue one is for z rotation. by default the tweening is set to bezier, which is an ease in, ease out, tween. meaning the gun will rotate slowly, then get faster, and then get slower again. this is useful for human movement. you want linear movement in this case, because it is a rotating gun.
Heres the important part
in the graph editor, press a, to select all the keyframes, press t and in the dropdown, select linear. this should solve your problem.
the answer was a bit lengthy, becaus I was trying to explain tweening, but If you want more information on it I suggest you look it up, or by a book on animation.
I hope this helps.
I think the accepted answer works but could be better. What you are seeing is an optical illusion. The barrels in the middle of the animation are lining up with the previous frame, so they appear to not be moving.
Enabling motion blur should let you see the motion throughout the animation, but still allow you to use smooth interpolation (so the spin up and slow down would be smooth).