Articles with tag: "propellers"

(Note: figures do not appear in the summaries below)

  1. NACA-TN-2212

    "in icing conditions, periodic attempts should be made to throwoff the accretions by increasing propeller speed."

    "The Effect of Ice Formations on Propeller Performance" 1

    Figure 18. Ice formation of encounter 1. Camber face. Peak efficiency loss, 10 percent.

    Abstract

    Measurements of propeller efficiency loss due to ice formation are supplemented by an analysis to establish the magnitude of efficiency losses to be anticipated during flight in icing conditions. The measurements were made during flight in natural icing conditions; whereas the analysis consisted of an investIgation of changes in blade-section aerodynamic characteristics caused by ice formation and the resulting propeller efficiency changes. Agreement in the order of magnitude of efficiency losses tobe expected is obtained between measured and analytical results. The results indicate that, in general, efficiency losses can be expected to be less than 10 percent; whereas maximum losses, which will be encountered only rarely, may be as high as 15 or 20 percent. Reported. losses larger than 15 or 20 percent, based …

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  2. Propeller publications by Porter Perkins

    "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

    Figure 1. Tunnel installation of hollow steel air-heated propeller for icing investigation. A tall, lean man with a distinctively tall nose inspects the propeller.
    I believe that this is Porter Perkins, circa 1946.

    Summary

    Porter Perkins investigations of propeller icing are reviewed. These are the earliest investigations by him that I found.

    Discussion

    Two areas are discussed, the gas heating of propellers, and the measurement of thrust.

    Gas heating of propellers

    • Investigation of Effectiveness of Air-Heating a Hollow Steel Propeller for Protection against Icing, I - Unpartitioned Blades. NACA-TN-1586, 1948. 1
    • Investigation of Effectiveness of Air-Heating a Hollow Steel Propeller for Protection against Icing, II- 50-Percent Partitioned Blades. NACA-TN-1587, 1948. 2
    • Investigation of Effectiveness of Air-Heating a Hollow Steel Propeller for Protection against Icing, III - 25-Percent Partitioned Blades. NACA-TN-1588, 1948. 3

    SUMMARY

    An investigation to determine the effectiveness of icing protection afforded by air-heating hollow …

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  3. Porter Perkins

    "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)

    Figure 1. Tunnel installation of hollow steel air-heated propeller for icing investigation. A tall, lean man with a distinctively tall nose inspects the propeller.

    From NACA-TN-1586. I believe that this is Porter Perkins, circa 1946.

    Summary

    Porter Perkins published on icing topics for over 50 years while at NACA, NASA, and other groups.

    Biographies and Memorials

    Porter J. Perkins is a senior aerospace engineer working in aviation safety as manager of airworthiness of research flight activity at the Lewis Research Center of the U.S. National Aeronautics and Space Administration (NASA), Cleveland, Ohio, U.S. He has specialized in research on aircraft icing for more than 25 years. His in-flight measurements to characterize icing clouds were later incorporated into U.S. icing protection certification standards. He has authored or co-authored more than 25 reports in the field of aircraft icing, and continues to participate in …

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  4. Electrothermal Ice Protection

    "... 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 from NACA-ARR-4A20. Ice formations on the thermal-electric de-icing blade shoes installed on a propeller of the XB-17F airplane. Shoe type: 2 Date: March 27, 1943 Indicated airspeed: 160 mph Propeller speed: 1010 rpm Pressure altitude : 10,000 ft Total power input: 402 watts for nine minutes Ambient air temp.: 9 to 11 F Average unit power: 0.53 watts/sq in. Type of ice: rime Unit power to shoe leading edge: 0.79 watts/ sq in.
    Figure 12 of NACA-ARR-4A20.

    Summary

    Electrothermal deicing is studied in the NACA-era.

    Key Points

    1. The power levels required for continuous anti-ice are challenging, so deicing was persued.
    2. Runback ice and residual ice are challenges for deicing.
    3. Analogue computers calculated transient heating and deicing.
    4. A chordwise-sequenced zone heating ice shedding strategy was devised.
    5. The current 787 jet aircraft uses electrothermal heating for wing anti-icing and de-icing.

    Discussion

    The electric powered deicing of propeller blades, as well as wing leading edges, was studied by NACA.

    The deicing of propellers is perhaps easier in some ways, as the centrifugal of the spin greatly aids the shedding of ice. Also, there are scale differences, as a wing airfoil usually has a larger chord length than a propeller. However …

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  5. Compressed Air Heat

    "the most economical icing protection ... consists of a system utilizing hot gas from a convenient heat source, namely, the turbojet-engine compressor" 1

    A jet transport airplane. There are many windows in the passenger cabin, implying may rows of seats. Notations read: "Shading indicates protected areas", which include the wing and empennage leading edges, the engine inlets, and forward windshields. Figure 1. Theoretical turbojet transport airplane assumed in calculations. Gross weight, 125,000 pounds; wing span, 158 feet; wing section, NACA 651-212; wing taper, 4:1; cruising speed, 500 miles per hour.
    From NACA-TN-2866.

    Summary

    Compressed air heating becomes common for ice protection in the jet era.

    Key points

    1. To support jet engine powered transportation, NACA had several studies of ice protection using compressed air heating.
    2. Deicing schemes were proposed to reduce the amount of air bled from the engines.
    3. Some innovative features, like continuously heated parting strips and recirculating hot air supply, did not see much use.
    4. Compressed air heating is used widely today for jet powered transports.

    Discussion

    As aviation entered the jet propulsion age, reciprocating-engine exhaust heat was not an option. However, the jet engine air compressor offers an ample (but not unlimited) supply of hot, compressed air that may be bled from the engine compressor airstream for ice protection, cabin heating, and other functions.

    Several NACA …

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