I could watch swallows for hours on end (and I frequently do). For me, they are quite simply the absolute masters of acrobatic flight. 
I count down the days in late Spring until they reappear from their winter retreats (it’s usually April when they come back to the farm) and I often pull up a chair in the garden, sit back and enjoy the free air show with Obi as they dive bomb, swoosh around low branches and accelerate to improbable speeds - even they sound like they are having so much fun with that trademark screech as they fly.
Obi, realising that he is never going to catch a swallow, sits and watches in awe, his head turned skyward at every gleeful screech.
I especially love it when the fledglings first attempt flight - that moment when they realise that they can do amazing things. The youngsters chase each other around my back garden, diving out of the sky to swoop low over the hedges as if they are practising a bombing run - seemingly just because they can and since swallows hatch two or sometimes three clutches in a season, I get to see that more than once every year.  
They are the spitfires of the bird world, the commanders of the sky and my swallow is the squadron leader, directing dive-bombing operations

Lead Time On All of Angus's Work is Approximately 3 Weeks