From AC 20-73A faa.gov.
Summary
- Different methods (test, analysis methods) can yield different ice shapes for the same conditions
- Measurements of ice shape parameters characterize the differences
- What is "too large" of a difference depends on unique factors for a particular case
- Engineering judgment is required to navigate the differences
Discussion
A method to characterize ice shapes
"Aircraft Ice Protection" AC 20-73A faa.gov lists ice shape parameters that can be used to compare ice shapes:
Applicants may use the lists of ice shape and water catch evaluation parameters in tables R-1 and R-2, ranked against their adverse airplane effects, to compare simulated and natural ice shapes. These lists are from SAE ARP5903 (Reference R20).
Table R-1. Ranking of Ice Shape Evaluation Parameters
Rank | Parameter | Units | Conservatism criteria |
---|---|---|---|
1 | Upper (suction surface) horn height | Equal or greater horn peak thickness (height) | |
2 | Upper Horn Angle | degree | Criticality of location … |