1. did not maintain desired drop back times, so it is difficult t o determine i f Level 2 ratings are due solely t o Fs/Nz. And References 12-14 primarily tested low values of CAP a t a single Fs/Nz, a range of Fs/Nz a t a CAP of 0.35, and variations i n Fs/Nz for CAP values above 1.0, so these studies do not cover a large portion of the dynamics investigated here. A tightly controlled in-flight experiment which holds drop back time t o Level 1 values and tests a narrower range of CAP i s needed t o validate this criterion. Aircraft such as the F-15 S/MTD, the F-18 High Alpha Research vehicle 15 (HARV), and the F-16 Variable Stability In-Flight Simulator Test i r c r a f t l (VISTA) should be capable of such testing. DROP BACK TI.ME TESTING
2. ShortPeriodDamping Figure 10. ConfigurationsUsedTo DetermineAcceptable
3. Short PeriodDamping Figure 12. PilotCommentsForDropBackTimeTesting sensitive, P10 prone responses which are not conducive t o precise tracking. Configurations with lower drop back time and higher short period damping resulted in more stable, predictable responses. Extremely overdamped systems with negative drop back times were s t i l l given Level 1 ratings even though pilot comments indicate displeasure with an increasingly sluggish response.
4. Figure 11 shows that configurations with negative drop back times resulted in Level 1 ratings. This i s in contrast to Reference 3 which suggests that negative drop back times are undesirable. Pilot comments from this simulation indicate that these overly damped, negative drop back configurations were acceptable for the fine tracking task simulated. However, pilots indicated that this response would probably not be desirable for a larger amplitude task or against a more actively maneuvering target. These comments support the statement in MIL-STD-1797A that allowable drop back times might be task dependent.