Blast from the Past: NACA Icing Publications

"The desirability for all-weather operation of turbojet aircraft has necessitated extensive research on methods of icing protection for the various engine components" From NACA-RM-E8C18.

"complete knowledge of the physical conditions under which supercooled clouds may exist, and the factors that cause a supercooled cloud to transform to an ice-crystal cloud is necessary" "A Photographic Study of Freezing of Water Droplets Falling Freely in

"supercooled water was concluded to become progressively more ice-like as the temperature is lowered" "X-Ray Diffraction Study of the Internal Structure of Supercooled Water" 1 SUMMARY A Bragg X-ray spectrometer equipped with a volume-sensitive Geiger cou…

"a need has arisen for a more complete understanding of the physical properties of supercooled water because few of the physical properties of water have been investigated at temperatures much below 0° C" "Experimental Values of the Surface Tension of Sup…

"very few supercooled droplets exist at temperatures lower than -35° C and the existence of an icing cloud at such low temperatures is probably an unusual occurrence."

"Although supercooled water has been observed and reported for over two centuries, considerable disagreement exists as to the degree of supercooling possible and the factors that influence supercooling."

"Although many important advances have been made in the control of ice formation on aircraft in flight, little progress has been made toward an understanding of the fundamental processes involved in the formation of ice or the prediction of such formation…

Public domain image by Donald Cook.

Public domain image by Donald Cook.

From ADS-4 ntrl.ntis.gov.

Public domain image by Donald Cook.

From AC 20-73A faa.gov.

from Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) (1990 version) ntrs.nasa.gov Prerequisites You need to complete the Aircraft Icing Handbook Water Catch Examples.

Public domain image by Donald Cook.

from Users Manual for the NASA Lewis Ice Accretion Prediction Code (LEWICE) (1990 version) ntrs.nasa.gov Prerequisites You need to complete the Aircraft Icing Handbook Water Catch Examples.

Introduction The "Aircraft Icing Handbook" DOT/FAA/CT-88/8-1, 1991 ntrl.ntis.gov.

Public domain image by Donald Cook.

from User's Manual for LEWICE Version 3.2 ntrs.nasa.gov Summary The "least that you need to know" to start using LEWICE, the NASA-provided icing simulation tool.

Figure 15 of NACA-TN-2904 ntrs.nasa.gov.

From "Aircraft Icing Handbook Volume 1", DOT/FAA/CT-88/8-1 ntrl.ntis.gov Summary After The Basics, you are ready for Intermediate level aircraft icing topics: Using handbook analysis methods Using computer icing analysis tools to produce ice shapes Prelim…

Introduction The good news is that these resources comprise thousands of pages of reading.

Introduction These terms are taken largely from ADS-4, with updates and additions.

Aircraft designs for flight in icing are improved and proven effective by several tools, including analysis, icing wind tunnel test, and flight test in icing conditions.

Several areas of the airplane may require ice protection: from ADS-4 (1963) Forms of ice protection There are several forms of ice protection used on airplanes.

Types of ice shapes As ice accumulates on a wing, it changes the shape of the airfoil.

The size of water drops in clouds The water that causes most aircraft in-flight icing is small drops in clouds.

Effects of icing in flight Airplanes can fly because engines produce thrust that propels it forward, and wings produce lift to counteract weight.

"Glaze Ice" formed in flight on an airplane: from "Effects of Ice Formations on Airplane Performance in Level Cruising Flight."

"The least that you need to know" Public domain image by Donald Cook Summary The Basics introduce core concepts and vocabulary of aircraft icing with images, "the least that you need to know".

"our knowledge of aircraft icing and the penalties associated with it has not changed substantially in the last forty to fifty years" 1 From NACA-TN-1586.

"Most, if not all of the recent accidents on record having icing as the probable cause could have been prevented if the flight crews understood the serious nature of the situation and had applied appropriate corrective action." 2 Summary Three publications

"In view of the number and complexity of the possible sources of error, it is not possible at this time to make a reliable estimate of the total accuracy" 3 Summary Calculations are made to assess the probability of encountering certain icing conditions.

"An approach to characterizing the severity of an icing encounter is to relate that encounter to the frequency of its occurrence." 1 Introduction Three publications with Porter Perkins as an author are included here.

"a 2-hour flight in ... a mixture of wet snow and freezing rain ... produced no adverse effects on the operation of the airship."

"Statistical values that represent the meteorological and climatic variations, which are associated with icing, will indicate what to expect in normal flight operations." 6 From NACA-TN-4314.

"As the demand for all-weather protection on aircraft for unimpaired and continuous commercial and military service developed, the detrimental effects of propeller icing on airplane performance became increasingly important" 1 I believe that this is Porter

"As the demand for all-weather protection on aircraft for unimpaired and continuous commercial and military service developed, the detrimental effects of ... icing on airplane performance became increasingly important" (1948) From NACA-TN-1586.

The NACA Technical Reports Server, circa 1999.

"It is thus desirable to have an economical method for solving the basic water droplet trajectory equations for an arbitrary airfoil." 1 The Use of Ko for Impingement Correlations The use of a modified water droplet inertia parameter Ko permits consolidat…

NACA-TN-2094 and investigators operating the water-drop-trajectory analog Figure 15 of NACA-TN-2904 Summary While no one is identified in Figure 15 of NACA-TN-2904, I speculate that these investigators are Helen M.

"the ideal flow field ahead of a ribbon is not a very satisfactory representation of the actual flow field in front of a rectangular body" NACA-TN-3658, "Impingement of Water Droplets on a Rectangular Half Body in a Two-Dimensional Incompressible Flow Fie…

"Although the airfoils used in these studies were a rather ad hoc collection of shapes and sizes, this report makes these data generally available and correlates the data as much as possible."

"Icing of air-intake ducts and scoops with subsequent reduction in pressure recovery and in air flow may adversely affect the operation of the aircraft."

"In spite of the simplicity, the configurations are reasonable approximation of those found on aircraft" NACA-TR-1317.

"... local concentration factors should be considered when choosing the location of devices that protrude into the stream from aircraft fuselages or missiles, or when determining anti-icing heat requirements for the protection of these devices."

"The presence of radomes and instruments that are sensitive to water films or ice formations in the nose section of all-weather aircraft and missiles necessitates a knowledge of the droplet impingement characteristics of bodies of revolution." 1 Summary W…

"One of the first essentials ... is a method for estimating or calculating the area over which water will strike the wing, and the distribution of water impingement over that area" From NACA-TN-1397.

"For a complete appraisal of the problem of ice prevention on aircraft, further water-droplet impingement data are needed" 1 Figure 5 of NACA-TN-1397 Water Drop Impingement on Surfaces Thread Summary Water-drop impingement quantification is key to aircraft

“The greatest of all our problems is ice.”

NACA Cleveland library, circa 1945.