Victor wrote:All that is being stated is that JSF can break the sound barrier and stay supersonic without using afterburner for a useful amount of time. That's all. As to why it stays supersonic for only 10 minutes, I don't have a clue. It could be the buildup of drag as you mention but I doubt it since wiki quotes Airforce Magazine saying:
"Although the Pratt & Whitney F135 F-35 engine was not designed to achieve a supercruise capability, the F-35 is able to maintain Mach 1.2 for a dash of 150 miles without using afterburners".
All that I am saying is that JSF cannot break the speed barrier in level flight without AB. Nor can it "maintain 1.2M" without AB. Either this, or the engine or associated components cannot be running at this power continuously for more than 10 mins. I have a hard time believing this.
Also, I never said drag builds up. It is instantaneous in nature and is dependent on speed, shape, weight and density of air. I said drag should be going down in cruise (same speed, same altitude) as weight is going down.
I suspect it is the sleek design with no pylons and other stealth details that enables this capability. The Concorde would cruise at supersonic speed without afterburners all across the Atlantic although it used afterburners for takeoff and climb to cruise, then it would shut them down. I believe XB-70 Valkyrie also could do this. Both were exceptionally clean, sleek designs.
If you read why the Concorde required AB to go past the Mach 1 barrier, and then could cruise all the way across the Atlantic (without falling back to Mach 1) without using AB, you would realize why I am asserting that:
1. F-35 cannot go past the speed barrier or maintain mach 1.2 without AB.
2. Why nobody wants to fly between Mach 0.99 and Mach 1.2.
Besides, the JSF is not sleek. None of the fighters carrying bombs internally can be. It is a trade-off.