I am trying to animate a drone with 6 spinning propellers in version 2.79b. I can make the props spin in object mode by selecting them and choosing individual origins for pivot center, however when I try to animate the spinning props only 1 prop spins. How do I animate all 6 props spinning at the same time? I have tried grouping, parenting and joining and still only 1 prop spins.
See that pretty record button by the keys at the bottom of the screen? Click that button. That's the Automatic Keyframe Button.
You also want to open up the action editor to actually see the keyframes.
So open up that editor, select all of the blades. Press, I, which iirc is insert keyframe. It should insert a keyframe for all of the blades, if not, you will just need to do it individually. This will make blender store the pose for those different blades at that frame in time. Now all you need to do to animate is go to a different point in time, and just rotate all of the blades. You can do them all at the same time if you've shift selected them before rotating, and you have 'individual center' selected for the transform origin, which is what you seem to have set, judging by the two circles between your shading and widget option.
You can extrapolate on the animation, which will make Blender continue the animation that you already started, further down the timeline. You can also just duplicate the keyframes of the final position of the blade, drag it to say, +60 frames, then at +30 frames, insert another keyframe where it's 50% of the animation to cause it to loop. You can also edit the curve of the animation in the IPO editor.
If you have any more questions, feel free to comment on this answer.
You may want to add a custom property to the drone object, and then keyframe the number value of the custom property.
For each prop, you could add a driver to its Z-axis rotation. In the driver settings, you'd add the custom property number to the current Z-axis value.
I found a video that explains the process a bit better than I can at the moment: https://youtu.be/Ht4m5txvWos
Thus by animating the custom property value, you animate all six props at once. Why go through all the trouble of repeating steps?
You may also want to look into animation F-curve modifiers, function or cyclic in particular. Thus with one of those applied to the custom property, you'd be able to keep the props spinning at a constant rate with only a single animation keyframe. The slope on the animation F-curve then correlates to the speed and direction of movement.
This could be more in-depth and complicated, but that gets more into rigging and scripting. Yes, that is more complicated. But if you use the same model more than once, it saves a lot of extra work in animating later on. (This is why rigging is an art/science in itself.)