EVALUATION OF HQ CRITERIA

The HQ criteria are also evaluated by the pilot in a fixed-base or motion-based simulators or finally in an actual airplane by performing a flight operation/maneuvers as specified by the design engineer/analyst. The HQ evaluation pilot should have several qualities [1]: (1) motivation, (2) communication skills, (3) confidence in his or her own capability and courage to give a frank opinion of the performance, and

(4) objectivity, and (5) piloting experience. A minimum of three pilots are required for such exercises. It must be added that the pilot’s opinion (rating) and evaluation also form part of this exercise. The HQ criteria for fixed-wing aircraft applicable to fighter aircraft are detailed in Ref. [8].

10.5.1 HQ for Large Transport Aircraft

The large transport aircraft (LTA) here is under Class III. It is important to compre­hensively study and evaluate the HQ of this class of aircraft. HQ criteria based on the dynamic characteristics of the aircraft only are [1,28] (1) LOTF of the aircraft, (2) open loop time response/pitch rate response criterion, (3) steady manipulator forces in maneuvering flight, (4) dynamic manipulator forces in maneuvering flight,

(5) compatibility of steady manipulator forces and pitch acceleration sensitivity,

(6) C* time-history envelope, (7) large supersonic aircraft criterion, (8) shuttle pitch rate time-history envelope, (9) dropback criterion, and (10) rise time and settling time criterion.

HQ criteria based on PAS are (1) pilot-aircraft closed loop dynamic performance, (2) pilot-aircraft ‘‘inferred’’ closed loop dynamic performance, and (3) modified

Neal-Smith criterion. HQ large transport aircraft software (HQLTASW) [28] is evaluated with the NLR’s database for Fokker F28/Mk6000 aircraft. This aircraft is a medium weight, twin-engined jet transport aircraft. The rate-command/altitude hold control system was selected for pitch and roll control. Longitudinal HQ evaluation for a transport aircraft is primarily important because the main purpose of a transport aircraft is takeoff, cruise, and landing. LOTF were used for the HQ evaluation studies. NLR evaluated HQ of this aircraft using the ground-based and IFS experiments, as well as various analytical criteria. A typical configuration, E5 [1], has a complete pitch rate TF:

q(s) 19.20 + 0.0831)0 + 0.706)0 + 0.870)

qCO) _ (s + 0.0775)0 + 0.838)0 + 10)(s2 + 2(0.699)(1.2)s + 1.44)

Some overall results of HQ evaluation using HQLTASW and compared with NLR’s predictions are shown in Table 10.9 (with entries as the HQ levels) for this config­uration.

The HQ levels specified by the CAP criterion vs. short-period damping ratio for the configuration E5 (and also other configurations studied in Ref. [1]) are depicted in Figure 10.5 [28]. The chosen configuration E5 meets the Level 1 HQ. The HQ level requirements of short-period frequency and load factor (with respect to alpha) are depicted in Figure 10.6. The E5 configuration meets the Level 1 specification as can be seen from the figure. The pitch rate history in normalized form should lie within boundaries specified in Figure 10.7. The configuration E5 falls within the specified boundaries. It might be necessary to modify certain criteria (like BW/N-S) for their applicability to LTA.