Two prototype engines, the Pratt &Whitney YF119 and General Electric YF120, also were developed and tested during the program.
Two prototype engines, the Pratt &Whitney YF119 and General Electric YF120, also were developed and tested during the program.
两个原型引擎,惠特尼yf119和通用电气yf120,还分别制定和测试期间的计划.