L Davidson, London to N Y in 11 minutes by executive jet of the future, Daily Telegraph 30 January 2016, p 36

In Canada, the 10-seater aircraft Antipode is designed to travel at 12 427 mph.  It will take off using rocket boosters that detach at a 40 000 ft, and then proceed on its scramjet engine.   A forward nozzle will collect air to cool the plane’s surfaces and muffle the sonic boom.