The heli needs a closer crop and the sky is a bit noisy. There is also a dark 'stain' around the tip of the main rotor (above the tail). The image could also use a bit more brightness and contrast. May I ask what camera you used for that photo? The rotorblades are quite bent.
As thanks as for the crop I expected that. The sky noise I can't figure out how to reduce, No clue on the "stain". The others are easy to fix. I use an Olympus OMD E-1, is the bending a good thing?
Noise can be reduced through Photoshop/plugins in Photoshop. And I was just curious about the bending, as you normally don't see that with DSLR's. And as far as I know it's not against the rules.