Talking of 1988 I lived near RAF Odiham then. I was out cycling across a country track near the airfield and had to stop and gasp at what I saw. A Chinook of all things was doing something I would have thought impossible. It was flying in a vertical horse shoe shape. It flew vertically upwards -that is to say nose first, above the tail. Then of course it would stall and fall back down, tail first. Before it hit the ground it turned horizontal and then flew vertically upwards, tail first till it stalled. Then it fell back down, nose first, did a U turn and flew back vertically upwards. If you haven;t seen it you would say I am telling porkie pies but I promise you I saw it and watched it for about ten minutes, continually doing this and wondering who has the job of clearing up all the vomit inside the aircraft. I cannot imagine the skill of the pilot.
I have also seen regular helicopters doing loops . . .