The plane had no missiles or guns on board, yet it became one of the most dangerous instruments of the Cold War.It remained invisible to Soviet radar for years. No missile could catch it. It was called the “black arrow” and was considered a technological marvel that could not be surpassed.It seemed like there would be no more platforms like this one. But today, something new is appearing on the horizon: the SR-72. And it promises to leave even the legendary Blackbird far behind.What is known about this hypersonic project? Why is the Pentagon so careful to hide its existence? Let’s figure that out right now!