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Icing Branch
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The Icing Branch participates in various collaborative partnerships with organizations, agaencies, industry, and academia.

Commuter plane preparing for departure SLD formation on prop spinner and inlet
The Icing Branch at NASA Glenn Research Center also participates in various collaborative partnerships and tasks involving other organizations, agencies, private industry, and academia.

International SLD Research Collaboration

The organizations listed at right have come together to coordinate research efforts with respect to the understanding of the physics of ice growth under Super-cooled Large Droplet (SLD) conditions. The aim of the research is to develop methods of compliance for icing certification in anticipation of an expansion of the certification envelope to include SLD conditions.

Background: Airworthiness authorities are considering the release of an operational rule affecting aircraft operations in Supercooled Large Droplet (SLD) icing conditions. Manufacturers will be required to demonstrate their aircraft can operate in SLD conditions for some period of time to facilitate a safe exit from this hazardous condition.

Compliance has typically involved actual flight into natural icing conditions, as well as the use of engineering simulations of the natural environment provided by icing tunnels and ice prediction computer codes. Since the SLD icing conditions occur less frequently than Appendix C icing conditions, it may be difficult and costly to demonstrate compliance by the use of natural icing flights alone. Therefore, it is expected that a greater reliance will be placed on the use of engineering tools (icing tunnels, tankers & computer codes) to demonstrate compliance.

The existing simulation tools have been focused towards representing the Appendix C icing envelope. Since SLD icing conditions have much larger droplet sizes than Appendix C conditions, the current simulation methods do not adequately represent the droplet dynamics and icing physics associated with SLD. Thus, it is necessary to augment the existing simulation tools to accurately simulate SLD conditions. This will require additional research to develop the appropriate SLD simulation capability.

The research organizations listed below have joined together to develop the needed SLD simulation capability. This collaboration leverages the unique technical resources residing in each organization and provides for a cost-effective and coherent international approach. The technology resulting from this collaboration will be openly shared, enabling each research organization to develop SLD simulation tools consistent with their unique requirements.

Collaborative Objectives
  • Mutually define areas for collaborative SLD research
  • Coordinate research with airworthiness authorities
  • Conduct research investigations using agreed upon technical process
  • Analyze and report results via SLD Website
  • Utilize research results to develop SLD simulation tools


  • Defense Evaluation Research Agency (DERA)
  • Office National d'Etudes et da Recherches Aerospatiales (ONERA)
  • NASA Glenn Research Center (NASA)
  • Federal Aviation Administration (FAA)
  • Civil Aviation Authority (CAA)
  • Wichita state University (WSU)
  • Cranfield University

Defined Research Activities

  • Investigation of reduced ice shape mass due to splashing of SLD
  • Study and documentation of SLD impingement dynamics
  • Study and documentation of SLD splash dynamics
  • Evaluation of scaling methodologies for SLD
  • Study of correlation between icing tunnel residence time and maximum supercooled drop size
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Last Updated: July 1, 2016
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