Slide 30 of 58
The idea of tailless design by itself is low risk. Tailless aircraft have flown successfully since the 1940s. Having the advanced FCS technologies ready for the FATE program depends on continued funding of the RESTORE program. Also, advanced FCS processor technologies are required for the integrated/adaptive controls (The C-90 chip is slated for availability in 1998.)
The all-moving wing tip and spoiler-slot-deflector require transonic wind tunnel testing to validate their full envelope effectiveness. Research of prior data indicate that these controls should remain effective at transonic speeds. However, the current applications of these controls (i.e., for yaw power) have never been tested at transonic Mach numbers.
As a fallback position, if the integrated/adaptive controls technologies are not available for FATE, the vehicle could be developed and flown by using conventional fly-by-wire systems in which a more restrictive flight envelope may be imposed. If the innovative controls are not ready or do not prove applicable to the FATE vehicle, more conventional tailless controls, like a clamshell or a spoiler, could be used.