“Sure, the plane indeed would be lighter, and could fly faster, but the reality is more likely that the plane will be lighter, be windowless, and fly at the exact same current speeds to further reduce fuel consumption and increase profits.”
The speed of sound (Mach 1.0) at 35,000 ft is about 660 mph. I think Emirates flies A380’s on many of their long haul flights. The A380 service ceiling is 43,000 ft, cruise speed is 587 mph/mach 0.89. So, the plane is already bumping against max performance for a sub-sonic aircraft....
“The speed of sound (Mach 1.0) at 35,000 ft is about 660 mph. I think Emirates flies A380’s on many of their long haul flights. The A380 service ceiling is 43,000 ft, cruise speed is 587 mph/mach 0.89. So, the plane is already bumping against max performance for a sub-sonic aircraft.”
The speed of sound is relative to the medium in which the sound travels. The speed of sound in air is affected by altitude, temperature, and humidity. But the speed is airspeed, not groundspeed. In other words, the speed of the aircraft is measured relative to the air around it. So, if an aircraft is traveling against wind current, its airspeed will be higher than its groundspeed, resulting in traveling slower when viewed from the vantage point of the ground (where departure and arrival times are the measure).
Aircraft not designed to exceed the sound barrier, depending on other limitations, may travel up to its critical Mach number (i.e. lower critical Mach number) at which any part of the aircraft is traveling faster than the speed of sound. (Because airflow around an aircraft speeds up and slows down as it cuts through the air, parts of an aircraft may reach the speed of sound even though the airspeed of the aircraft has not reached this point.)
Going windowless will bump these numbers higher and could also make it easier to design aircraft to go supersonic. Whether they actually fly faster in service, as you point out, will probably be a factor of whether being windowless affects the critical Mach number of the particular aircraft. Either way, the jets will fly faster or cheaper or both.