关于F35 canopy 的 arch support , 至今还有人争论. 我觉得这个答案比较靠谱.
"Because the F-22's archless canopy is a lot thicker. The F-35 went to a thinner canopy and added a composite arch support on the inside (the coated transparency is still one piece for stealth purposes). This allows the det-cord system to be used.
One of the reasons they went with this system is that it is lighter, but another is that it is faster than the traditional US practice of using a 2-step ejection system that first jettisons the canopy then firing the seat. Because of the necessity to wait for the canopy to tumble clear from the ejection path, the ejection seat has to wait a second or so before firing. This is a second or so which the pilot of a STOVL aircraft like the the F-35B doesn't have if there was a sudden loss of hover thrust."