Those who defend the operation of this aircraft above the maximum take off weight for the conditions should consider this.
Concorde, as a delta wing aircraft is unlike any other airliner with which we are familiar. Lift is provided by the generation of vortices, and the lift (and hence drag) generated is proportional to the angle of attack. If you need more lift, you need more angle of attack, and so you also need thrust to go with it.
A delta does not ‘stall’, you can have ninety degrees angle of attack if you like, as long as you have the thrust to go with it. At slow speeds, a high angle of attack is necessary, and so also a high thrust.
Hence Concorde has additional characteristic speeds called Vzrc and Vzrc3 (V zero rate of climb) which corresponds to an airspeed that you need to have to maintain level flight with four (three) power units operating at rated thrust. V2 for the aircraft is defined as 1.125 Vzrc. If you are below this speed for the number of power units specified, gravity takes over, and you WILL descend.
The accident report specifies that for a Concorde operating at maximum certificated weight (185t) Vzrc3 and Vzrc2 are 205kt and >300kts for flight with the gear down.
The flight crew were using Vr of 198 and a V2 of 220kts.
The aircraft was rotated at 188kt and left the ground at 201kt. The aircraft was below a speed to safely suffer a single engine failure.
The pilot continued to increase the pitch attitude and the speed reduced further. By the time engine 2 was shut down, the airspeed was 199kt. By the time control was lost the angle of attack had been increased to 25 degrees and the speed reduced to 136kt.
In a normal aircraft, speed is important, in Concorde it is vital. The aircraft was above its maximum weight, the take-off in a tail wind was a critical factor, and the aircraft was mishandled during a critical failure.
Those are the facts, they are taken straight form the BEA report.