"It is observed that severe icing is not predicted over large areas." Introduction This is one of the shortest post that I have written, as it is more outlining a mystery, that I have not yet sorted out, than a full review. Summary In Conclusions of the Meteorology of Icing Clouds Thread , there is a time-line of how the NACA understanding of the icing conditions evolved, focussing on liquid water…
"Tests to determine the performance of an icing protection system ... are of little value ... unless they can be subjected to an analytical treatment, and reduced to a generalised form which is applicable to conditions other than those under which the tests were actually made." Lecture No. 12b, "NOTE ON THE FLIGHT TESTING AND ASSESSMENT OF ICING PROTECTION SYSTEMS" 1 Summary An alternative view of…
"If the [ice] crystal is exceedingly small, rather than growing, it may melt." SUPERCOOLED CLOUDS 1 Summary Several aspect of icing clouds physics are discussed. Key Points Supercooling and nucleation rates are key to the formation of icing clouds. Vapor pressure differences of liquid water and ice play a role. Tips are given for recognizing supercooled clouds. Types of icing clouds are discussed.…
Thirteen lectures show the "state of the art" in 1953. See Lecture No. 6, "Energy Exchanges During Icing", Messinger, Bernard L. Summary Thirteen lectures show the "state of the art" in 1953. Key Points This was the best aircraft icing training and design guide available at the time. Several lectures are extracts of earlier works, or were republished later. Selected lectures are reviewed. Abstract…
There was remarkable progress in the three-year span 1946 through 1949. from "FLIGHT INVESTIGATION OF METEOROLOGICAL FACTORS CONDUCIVE TO AIRCRAFT ICING", William Lewis, 1947. 1 Summary The most enduring legacy of the NACA publications on icing meteorology is their direct influence on the current icing regulations. Key Points NACA publications contributed heavily to the creation of the Appendix C…
"A Probability Analysis of the Meteorological Factors Conducive to Aircraft Icing in the United States" "the probability analysis presented does provide an indication, heretofore unavailable, of the combinations of icing conditions having equal probability" Summary The icing design values in NACA-TN-1855 were found to have an exceedance probability Pe=0.001. Key Points A rigorous probability…
"A Summary of Meteorological Conditions Associated with Aircraft Icing and a Proposed Method of Selecting Design Criterions for Ice-Protection Equipment" 1 "the heat required for protection for this [severest] situation is several times that required for the most probable icing condition." Summary By allowing some ice to accumulate in severe icing conditions, the peak energy requirements for ice…
"the collection of data indicating the maximum extent, severity, and frequency of conditions" "Meteorological Analysis of Icing Conditions Encountered in Low-Altitude Stratiform Clouds" Summary Data about the horizontal and vertical extend of icing clouds. Key Points A factor of distance traveled in icing related to liquid water content is noted. The maximum vertical extent of icing clouds is…
"Recommended Values of Meteorological Factors to be Considered in the Design of Aircraft Ice-Prevention Equipment" 1 "Progress ... has been handicapped by the lack of sufficient data on the meteorological factors." Summary Icing conditions for the design of equipment are proposed, which are later part of Appendix C. Key Points Classes of icing conditions are proposed. Recommendations are made by…
"Complete information concerning the fundamental physical processes that determine the structure of clouds and cloud systems has necessitated a statistical approach to the problem." "Investigation of Meteorological Conditions Associated with Aircraft Icing in Layer-Type Clouds for 1947-48 Winter" Summary Measured icing conditions in 1947-48 were consistent with prior measurements. Key Points…
"liquid water concentration at any point in the cloud may be calculated by considering an air parcel lifted adiabatically from the condensation level" "Icing Properties of Noncyclonic Winter Stratus Clouds" Summary Adiabatic lift theory is used to estimate the liquid water content of clouds. Key Points Adiabatic lift theory is used to estimate the liquid water content of clouds. Drop size…
"The maximum icing conditions in which ice-prevention equipment will be expected to provide adequate protection" from "FLIGHT INVESTIGATION OF METEOROLOGICAL FACTORS CONDUCIVE TO AIRCRAFT ICING", William Lewis, NACA Conference on Aircraft Ice Prevention A Compilation of Papers Presented by NACA Staff Members. 6505/NACA-1947/8, 1947. Summary Early Ice Protection Systems were designed without…
"... Before attacking what appeared to be a new icing problem we should study the icing work of the 1940's and 50's." 1 From NACA-TN-2904 Summary I have made this blog up as I went along. I have a general plan to cover all 132 icing publications in the "Selected Bibilography of NACA-NASA Aircraft Icing Publications" , but I also find other interesting, related items along the way. Future topic…
"The industry has now passed through the experimental stages of heating and anti-icing ..." (1946) 1 From NACA-ACR-A-53 , 1941. Summary Ice protection system development continues to address new challenges. Key Points Design guides can lead you to "adequate" designs for several technologies. Design guides provide procedures to compare candidate systems. Optimal designs and new requirements may…
"An aircraft engineer can use this report to design adequate ice protection systems for any type aircraft for any flight mission profile." 1 Figure 4.2-2 of ADS-4. Summary The knowledge of aircraft icing matured to produce engineering design manuals. Key Points NACA publications contributed heavily to later design manuals. Extensive design publications distilling research into practical methods…
Summary While icing weather is a serious topic for aircraft, several sources have used [debatably] humorous, instructive illustrations of the hazards. Discussion Aviation Weather For Pilots and Flight Operations Personnel. AC 00-6A (Cancelled) 1 See also The Greatest Thing That You Have (Probably) Never Read: AC 00-6A (Cancelled) "Mechanical De-Icing Systems" 2 Air Command Weather Manual (Canada)…
"ice formation can be redefined in more general terms as a thermodynamic problem" 1 (1936) Summary The thermal analysis of icing conditions has unique challenges, including the determination of heat transfer coefficients and fraction of the surface wetted. Key Points Measured heat transfer coefficients in dry air can be different between flight and tunnel tests, due to free stream turbulence.…
"I am surprised to find that there are so many details which have not been anticipated before the de-icing tests were started." (1942) Figure 1 from NACA-TN-1789. Summary The effects of icing on small components must be addressed. Key points Flight tests in natural icing revealed (and still reveal) small component icing effects. Fuel vents designs were evaluated. "At present very little is known…
"... ice on the airplane windshield, which is known to be a problem in urgent need of solution." Figure 14 from NACA-TN-1434. Summary Ice protection for windshields matured during the NACA-era. Key points In 1939: "The existing practice of making the airplane windshield retractable or removable by the pilot ... against loss of vision due to rain or ice" By 1947, window heat designs similar to…
"Alcohol as a means of protection against ice formation on propeller blades is widely used by commercial air lines on transport airplanes." 1 Figure 2 from NACA-RB-4F06. Summary Freezing point depressant fluids were used widely in the NACA-era. Key points The use of freezing point depressant fluids were not pioneered by NACA, NACA studied improvements. Analysis methods were developed in the…
"an effective system for ... wing surfaces to prevent the formation of ice requires knowledge" Figure 2 of NACA-ARR-A506 Summary Combustion heated air, independent of the engines, was used on some aircraft. Key Points Combustion heaters were developed independently of NACA. 38 NACA publications detail technical aspects of aircraft heaters, including many details on heat exchangers, maturing…
"... the power required for ice prevention may be excessive for certain applications, although sufficient power for some degree of ice removal may be provided readily." 1 Figure 12 of NACA-ARR-4A20. Summary Electrothermal deicing is studied in the NACA-era. Key Points The power levels required for continuous anti-ice are challenging, so deicing was persued. Runback ice and residual ice are…
"the most economical icing protection ... consists of a system utilizing hot gas from a convenient heat source, namely, the turbojet-engine compressor" 1 From NACA-TN-2866. Summary Compressed air heating becomes common for ice protection in the jet era. Key points To support jet engine powered transportation, NACA had several studies of ice protection using compressed air heating. Deicing schemes…
"an airplane that will be immune from the dangers of ice accumulation ... is only a matter of technical development." 1 Summary Practical wing heating designs are developed and proven in natural icing flight tests. Key Points Flight tests were used extensively, as icing wind tunnels were still under development. Much detailed development over 10 years was required. "Existing data indicate that…
"A demon was operating the throttle." S. W. Sparrow, 1920. 1 From NACA-TR-982. Summary Carburetor icing has been a known hazard for over 100 years, and many protection strategies were studied in the NACA-era. Key Points Carburetor icing has been a known hazard for over 100 years. Part of the hazard can occur in clear air (throttling icing and fuel-evaporation icing). "The NACA induction-system…
"The removal of ice from a De-Icer surface depends on the true adhesion of ice to rubber..." 4 Image from “Engineering Summary of Airframe Icing Technical Data” ADS-4, 1963. Summary Pneumatic boot deicers were the first widely used form of aircraft ice protection, and are still used today. Key Points Deicing boots were developed independent of NACA. Oil coatings aid the shedding of ice. NACA…
"The documents were so old, however, that they were not listed in the modern computerized library search systems, and some of these documents were out of print." 1 NACA Cleveland library, circa 1945. Summary I can usually get even rare and obscure publications through inter-library loan from my public library, but these were reported as having no loanable copies available. Discussion I have tried…
"The possible methods for overcoming the ice hazard ..." 1 From NACA-ACR-A-53, 1941. 2 Summary Numerous methods were tested to find effective aircraft ice protection in the NACA-era. Introduction During the war, more than a hundred cargo planes of the Air Transport Command, flying from bases in India over the Hump to battlefronts in China, crashed in the Himalayas. Most of them were brought down…
"ChatGPT may produce inaccurate information about people, places, or facts" From https://chat.openai.com/ ChatGPT August 3 Version (2023). Summary The image was generated with DALL-E 2 with the prompt "An airplane from 1946 flying with engine exhaust heat ice protection". I have no idea what the orange thing (ribbon and bow?) is on the wing. I also tried letting ChatGPT write a blog post. Prompt:…
"... Before attacking what appeared to be a new icing problem we should study the icing work of the 1940's and 50's." 1 One year of "Blast from the Past: NACA Icing Publications" Image from "NACA Conference on Aircraft Ice Prevention A Compilation of Papers Presented by NACA Staff Members" 6505/NACA-1947/8, 1947. (colorized) (and the new logo for 2023) I made 50+ posts in the past 12 months. I am…
"difficulties with the calibration proved to be more serious than had been anticipated" 1 Summary The meteorological instruments and data from the NACA-era are still used today. Key Points The rotating multicylinder was the primary instrument that determine the values in the current Appendix C icing regulations. Other instruments gave supplementary data, but were calibrated against the rotating…
"A measure of the concentration of liquid water in a supercooled cloud is of considerable value in determining the severity of aircraft icing conditions" "A Simplified Instrument for Recording and Indicating Frequency and Intensity of Icing Conditions Encountered in Flight" 1 Summary An instrument for automatically recording the occurrence of icing and liquid water content values is described. Key…
"Because the charge placed on the droplets is a function of the droplet size, the size spectrum can be determined ..." 1 "An Instrument Employing a Coronal Discharge for the Determination of Droplet-Size Distribution in Clouds" Summary Electrical charges imparted to water drops allowed easier measurement of impingement on cylinders. Key Points This was a multicylinder instrument that relied on the…
"The subject of aircraft ice protection has provoked much controversy and discourse among theorists, designers, laboratory and test engineers, and flight operations people." 1 Summary The state of the art in 1969 of aircraft icing is documented in 16 presentations. Abstract The subject of aircraft ice protection has provoked much controversy and discourse among theorists, designers, laboratory and…
"Blast from the Past: NACA Icing Publications" now posts on the Mastodon social network. You do not need an account to view the posts, they are available at historians.social/@icinganalysis . If you have an ActivityPub or "fediverse" social media account, you can follow @icinganalysis@historians.social. At the moment, the posts are "old" ones (aren't they all?), but they will eventually (over…
"... it is believed that a comparison of the water-drop impingement over several different airfoils ... is of interest" Figure 5 from NACA-TN-1397 NACA-TN-1397, "A Method for Numerically Calculating the Area and Distribution of Water Impingement on the Leading Edge of an Airfoil in a Cloud." 1 NACA-TN-2476, "An Empirical Method Permitting Rapid Determination of the Area, Rate, and Distribution of…
"a simple and rapid means for measuring the liquid-water content of clouds" 1 NACA-RM-E50J12a, "Flight Instrument for Measurement of Liquid-Water Content in Clouds at Temperatures Above and Below Freezing" NACA-TN-2615, "The Calculated and Measured Performance Characteristics of a Heated-Wire Liquid-Water-Content Meter for Measuring Icing Severity" NACA-RM-A54I23, "A Heated-Wire…
"it is necessary to measure the sizes of the droplets within the clouds." 1 NACA-RM-E50K01a, "Flight Camera for Photographing Cloud Droplets in Natural Suspension in the Atmosphere" NACA-RM-E51G05, "Adaptation of a Cascade Impactor to Flight Measurement of Droplet Size in Clouds" NACA-TN-3592, "An Oil-Stream Photomicrographic Aeroscope for Obtaining Cloud Liquid-Water Content and Droplet Size…
"This [rotating disk] device should prove very useful in both the formative and statistical investigations." "A Review of Instruments Developed for the Measurement of the Meteorological Factors Conducive to Aircraft Icing" 1 from NACA-RM-E51E16 2 Summary "A review ... of meteorological factors conducive to aircraft icing reveals outstanding needs" for icing instrumentation. Key points Nine…
"Icing is as close to pure witchcraft engineering as you can get." Thomas S. on LinkedIn. Ice on a NASA airplane from a research flight test. From commons.wikimedia.org . Summary This website was written with people in mind (engineers, aerodynamicists) who already know something about aircraft and aircraft icing. To make it a little more understandable to others, I summarize here the assumed…
"A review ... of meteorological factors conducive to aircraft icing reveals outstanding needs" Meteorological Instruments Thread Summary Several instruments were developed and improved during the NACA-era to measure icing conditions. Numerous modes of physics were explored, and distant descendants of some devices are still used today. See also Icing on cylinders , and Calibration of the NACA Icing…
"effects are scaled appropriately between Appendix C and SLD conditions using the existing scaling methods" Summary Icing wind tunnel uses and challenges for large drop icing are discussed. Key points Since 2014, supercooled large drop (SLD) icing has been part of (US) 14 CFR Part 25 icing regulations (Appendix O). Physics make current icing wind tunnels challenged to reproduce the freezing rain…
"With a thermal IPS, energy reduction can be achieved by operating in a ‘running wet’ mode under more extreme icing conditions." "Evaluation of Alternative Altitude Scaling Methods for Thermal Ice Protection System in NASA Icing Research Tunnel" 1 Summary A procedure for scaling conditions for ice protection tests is detailed. Key Points Scaling methods for ice protection testing at sea level…
"a condition of supersaturation, which promotes the growth of frost deposits" Summary Supersaturated humidity can affect icing wind tunnel results. Key Points Some observations of supersaturated humidity conditions were made in the NACA-era. Supersaturation was associated with frost on test article afterbodies. Recirculating icing wind tunnel conditions are calculated to tend to be supersaturated.…
"... it was not surprising that scale ice shapes were again a good match for the reference" NASA/CR-2004-212875 1 Summary Similarity calculations for ice shapes are detailed. Key Points Several scaling methods with differing parameters are compared in tests. "The Ruff method, supplemented with the constant-We L approach to calculate scale velocity, is recommended" Examples are included of how to…
"An unfortunate fact is that if proposed additional scaling parameters prove to be what is required to conduct improved subscale tests, icing wind tunnel subscale tests are likely to be even more restrictive." "Proposed Modifications to Ice Accretion/Icing Scaling Theory" 1 Summary Water surface tension is identified as a factor in ice shapes and test similarity. Key points 18 dimensionless…
"drag coefficient (Cd) was used as an index of similitude by quantitatively indicating how much the shape or ice surface changed" "An Empirical Look at Tolerances in Setting Icing Test Conditions with Particular Application to Icing Similitude" 1 Summary An investigation into which icing conditions parameters affect icing similtiude as measured by aerodynamic drag effects. Abstract Often, engine…
"It would be beneficial to the icing community if the feasibility of using scale models in these tests could be proven." "Analysis and Verification of the Icing Scaling Equations" 1 Summary An expanded set of icing similarity terms are derived and tested. Key Points Water drop impingement similarity is simplified using Ko. Icing heat transfer similarity terms derived from Messinger are added.…
"If the values of the K and φ parameters for the model and full-scale nacelle are maintained the same, the icing characteristics of the model will be similar to the icing characteristics of the full-scale" Summary Early examples of icing test scaling are noted. Key Points Three publication that mention scaling are reviewed. Some challenges with scaling are noted. A airfoil design of a full scale…
"Considerable time [was devoted] to means for controlling the amount of water sprayed into the air stream, the size of water particles, and the temperatures of the air and water" 1 Summary Calibration methods evolved during the NACA-era Key Points Early tests had informal calibrations, partly due to a limited understanding of the natural icing environment. Rotating multicylinders were the most…