A few pages back there was a question or 2 about the Sigma 150-600 C being a decent lens for shooting airshows. My answer is a big YES & I've posted a few shots it was used for. These are from the last Radio Control event which is what I shoot throughout the summer because there are lots of these events & very few full scale events in the region. All shot with a 1D4 & the Sigma hand held in Tv mode. All models are at full speed, which is 100 MPH & up & usually no more that 150 feet away from me.
You did a good job!
I find shooting model airplanes much harder than real planes, especially at slow shutter speeds.
Those little planes move very fast!