Downloaded from https://www.everyspec.com ADS-79D-HDBK B.5.1.2 Flight environment. Table B-VI shows typical Flight Environment parameters, some of which are important to Regime Recognition as well. B.5.2 Digital source collector design for structural usage monitoring. B.5.2.1 Onboard flight state sensing . Flight state parameters are used as inputs to the regime classification algorithms. According to McCool and Barndt (2004), Gross Weight, Airspeed, Altitude, and Outside Air Temperature are four key parameters.
These parameters represent very important measures of aircraft usage and loads and are likely to characterize the flight test maneuver load database and fatigue calculations for most platforms. Although these and other important state parameters may be estimated or derived from various other sources of input, the resulting accuracy and fidelity should be consistent with the range of operational load conditions and configurations intended to be covered by each flight test regime and its associated description and tolerances.
The set of flight state inputs provided in Table B-VII is intended to serve as an example of the type of parameters which a hypothetical regime classification algorithm may use. The digital source collector for a particular aircraft should be designed to collect information necessary to either directly record or indirectly estimate/derive the required input parameters for the aircraft‘s particular regime classification algorithm. The implemented list of parameters will be a function of available parameter sources onboard the aircraft and the input needs of the classifier algorithms.
However, where possible, one should select natively available flight sensor sources and data buses (such as a 1553 data bus) that are available on the aircraft in lieu of adding custom instrumentation. This design decision serves to reduce the cost and complexity of implementation as well as ensuring that flight state sensors are guaranteed to be operational and calibrated as part of normal aircraft maintenance procedures.
The blade stall indication listed in the Table B-VII example could represent recording a Cruise Guide Indicator (CGI) signal such as for Boeing Philadelphia products, estimation/ calculation of Sikorsky‘s Equivalent Retreating Indicated Tip Speed (ERITS), or some novel approach to indicating blade stall. It is noted that the example lists various notional derived parameters which may be of use for similar purposes, including Referred Gross Weight, Blade Load (―C T /σ‖), and advance ratio (―μ‖).
Airspeed ratios to the maximum level flight airspeed (V h ) or the ―never exceed‖ airspeed (V ne ) are often used to characterize airspeed in fatigue calculations and may be based on tabulated values for V h or V ne as a function of Referred Gross Weight. Use of these blade stall indications or tabulated airspeed characterizations should be considered when determining the fidelity requirements for Altitude or Gross Weight estimation. Mission planning may provide supplemental data to assist with selecting appropriate V h or V ne values for the flight.
In addition to the parameters shown in Table B-VII, regime classification algorithm designers may also consider whether the potential usefulness would justify the additional expense of requiring the 53 TABLE B-VI. Typical military helicopter flight environment parameters (EXAMPLE ONLY) Local Base Environment – Off Board Data Collection 1 Geographic Description of Theater (Desert, Mountains, etc) 2 Shipboard Operations ( landing severity and salt water effects) 3 Ambient Temperature - exposure (duration) at extremes Operational Environment – Collected On-Board 1 Outside Air Temperature 2 Altitude