Two very nice photos here. I particularly like the Red Arrows shot - looks very good to me overall. Very slight jaggies on the horizontal white stripe down many of the Hawks, but not enough to cause a problem, as the contrast is notable there, and that always creates sharpening issues. The crop seems good to me, though I may be tempted to have the formation sitting slightly higher in the frame - as it is now there is a little too much space above when compared to that below.
The Nimrod also looks nice at this large size - definitely you would be safer at 1024, but I don't see major flaws. It is a little dark underneath, and I wonder whether it could cope with the midtones being lifted a little, without it looking artificial in any way. But you need to be careful there, as we know how the screeners don't like to see anything that could be interpreted as lifting detail too much - e.g. the shadow/highlight tool.
Good luck with them.