According to the chart on page 47 at TL6 you're only allowed enhanced mechanical controls and they are limited to a transonic airframe, even though you can build a supersonic airframe at TL6 (see table on page 30). As RL early supersonic fighters didn't have electronic controls I assume this is an error and the enhanced mechanical controls should allow up to supersonic airframes.
Unofficial TNE errata: FF&S aircraft controls
Part of thread: Unofficial TNE errata: FF&S aircraft controls · 0 replies
According to the chart on page 47 at TL6 you're only allowed enhanced mechanical controls and they are limited to a transonic airframe, even though you can build a supersonic airframe at TL6 (see table on page 30). As RL early supersonic fighters didn't have electronic controls I assume this is an error and the enhanced mechanical controls should allow up to supersonic airframes.