ZA,
Quite right - I was really referring to the OP question, not specifically to the barrel roll. I guess I was just too lazy to quote the appropriate piece!
Here's his own description of a typical display sequence of about 6-7 minutes:
These demonstrations varied over the years according to the audience and the conditions. Like providing a good seat at the cinema, the first thing to do if possible was to fly with the sun on the backs of the audience, so that they were not blinded all the time, and at a distance which did not make them strain their necks. Always, if I could, I operated up and down wind: if the wind was strong and one upward-rolled across it, the manoeuvre could look untidy, and sometimes would put one in the incorrect position for the next manoeuvre.
As a rule the drill was to take off and not climb, but pause with the wheels coming up and the machine just clear of the ground, and at 150-160 IAS pull up slowly but firmly into a half loop, finishing with a half roll at the top. I never really liked this as one cough from the engine and I should have been in real trouble: at the roll stage I was in any case holding the machine by maximum engine power well below the normal stall and the slightest coarse handling on the controls would cause the machine to flick out.
I would continue this in maybe another couple of half loops and rolls until I was over 4000 ft and then, placing myself in the correct position over the aerodrome, half roll again and go into an absolutely vertical dive with full engine and maximum revs to pull out a few feet from the ground and go into a vertical roll to the left, a vertical roll to the right and a half roll to the left with a half loop, and then pull out to repeat the manoeuvre in the opposite direction.
Pulling out in another half loop in the other direction, the throttle would be snapped back and plummeting down vertically one could get in two complete aileron turns to pull out again and open the throttle to do the same thing in the other direction. Having now used up most of my height and speed, I would pull up vertically to about 1000 ft and in a tight half loop at the right moment flick the machine into a full flick roll.
This I always felt was a tricky one. It took a lot of judgement to do it accurately, because very often the manoeuvre was so sudden and vicious that on checking the machine it would sometimes be slightly out of line and I knew it could look untidy. I could usually get one-and-a-half to two full flicks of a roll on the horizontal but for the sake of control and tidiness I usually settled for one, which I knew I could judge to a nicety. In practice I could get in about the same with the vertical flick rolls, but with these I found it almost impossible for me to judge when to check and come out clean.
I have never seen anyone flick-roll a Spitfire and I must say that I always found it a little frightening to abuse a machine and have it flash out of your control, if only for a few seconds, like a young spirited blood-horse.
On the pull-out from the flick roll sometimes I would open the engine flat out in another vertical climb and, at approximately 1200 ft, push the nose over forward then, with the engine closed, complete the half of an outside loop, usually in those days called a `bunt'.
I never really liked this manoeuvre either: it was easy but required heavy pressure forward on the control column and you could not afford to misjudge at 1200 ft: with the nose going over down towards the ground the speed built up at such an alarming rate that it left no room to change your mind until it was too late. At the bottom of the inverted dive I would usually 'round off' to a few feet above the ground and then, with as much pressure as I dared use on the control column - I say 'dared' because I found it more disconcerting and frightening to 'black-out' from excessive negative `G' than I did from high loads in the positive position - I would push the machine into an almost vertical climb and, as it lost momentum from the negative 'G' position, pull the control gently over to form a half-loop, hoping as I did so that the engine would burst into life as I opened the throttle.
This it usually did with a spectacular sheet of flame pluming from the exhaust stubs caused by unused fuel which had accumulated during the inverted manoeuvres.
With the engine now on full power I would do a series of very low rolls left and right in front of the audience at below hangar height, finishing in the inverted position from which I would 'raise' the undercarriage, pull into a tight, fast engine-off turn and lower the flaps, as I touched down for the landing.
SD