Chokdee: 56" for JNB is fast, it's often well over a minute. With regards to Concorde which was mentioned in the early posts as being up to 200 mph ground speed in 12". I don't think so!!!
On 8th August, it was very hot in London, the highest recorded temp at LHR was recorded two days later at 100 F. We were fully loaded and were advised that we were at max fuel.
During the t/o roll, I did not keep a close an eye on my stop watch as I was too busy grinning and enjoying the noise and wanting to get up and dance down the aisle.
However, G-BOAC rotated after
about 35/40 seconds of roll. I understand that Conc rotates at approx 250mph (217 knots, I think?). If those figures are correct, that would mean that we must have taken about 30" to get to 200mph. I sit to be corrected.