A very striking fellow, and quite a challenge to expose well, which I feel you have done very well here. The whites look quite good.
Nice full down stroke on the wings, extended legs and climbing angle all nice.
I might try to dodge the far underwing a tiny bit, and consider a smidge more room on the right, and because he is climbing, recrop so he is slightly lower in the frame with room to climb.
Lovely in flight image, just love the upturned head. As mentioned good exposure and good detail in the blacks. I have never seen one of these before TFS.