4h 10m would be an excellent flying time for CCS
for Concorde, but could only be achieved on a non-stop flight.
It would not be possible to make a refuelling stop at the Azores in that flight time, even if you only spent 20 minutes on the ground - which in itself would be difficult, as a 45 minute stop would be much more typical.
Fritzi, MxCtrlr, Gigneil
Sorry, but the Air France Concorde did fly CCS
non-stop, though it didn't manage it on every flight. I can't add much to what Alain Mengus
has already posted.
As you say, flying at altitude near the Tropics, Concorde benefits from the generally very cold upper air temperatures. The engines become more efficient, fuel flows reduce, and consequently the range increases by a few hundred miles.
Some may think it odd that the upper air near the Equator is relatively cold, and that the upper air over the Poles is relatively warm, but that is what happens.
When discussing Concorde's maximum range, there is another factor, not often discussed, that I would like to mention.
Just like any other aircraft, Concorde must carry sufficient fuel on board to enable her not only to reach her destination with standard fuel reserves still remaining, but also to reach an alternate airfield, following an in-flight engine shut down at any stage of the flight.
This last part, for Concorde, needs to be carefully planned. If an engine has to be shut down in supersonic flight, Concorde will then have to descend about 25,000 ft, and slow up by around 700 mph.
In this new flight regime, now flying subsonically, in the much stronger winds and warmer temperatures below the tropopause, she is far less fuel efficient, and her maximum range will have suddenly reduced by about 25%. An airfield that may have been comfortably in range whilst cruising at FL560 and M2.0 on four engines, may no longer be in range down at FL310, and M0.95, on only three engines.
At the flight planning stage therefore, we must
ensure that sufficient fuel is carried to retain a three-engined diversion capability at all
times, from any
point along our route, to a suitable alternate airfield.
On the long over-water routes to the Caribbean and Latin America, with only a few, distant, alternate airfields available, and adverse subsonic winds and temperatures, the fuel required to achieve this will generally exceed the fuel required to destination, and become the limiting factor.
On planning such routes, the length of the route itself often becomes of secondary importance, with the distance, and fuel required, to an in-flight alternate being of prime importance.