Quantifying the Effects of Humidity on Density Altitude Calculations for Professional Aviation Education

Guinn, Thomas A.; Barry, Randell J.

doi:10.15394/ijaaa.2016.1124

Cited by 7 publications

(9 citation statements)

References 5 publications

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“…When the temperature rises above the standard temperature for a particular place, the density of the air in that location is reduced, and the DA increases. 3) Humidity: An increase in the amount of water vapor in the air leads to a decrease in air density, which in turn leads to an increase in the DA (FAA 2016;Guinn and Barry 2016) Although the importance of accurate DA calculations is well known among aviators, most introductory pilot training manuals fail to address the impact that atmospheric humidity has on the results (Guinn and Barry 2016). The published performance criteria in the ''Pilot's Operating Handbook'' (POH) are generally based on ISA conditions at sea level (598F/158C and 29.92 in.…”

Section: B Damentioning

confidence: 99%

“…Hg/1013.25 hPa) without consideration of dewpoint temperature (FAA 2008). The calculation of DA for aircraft performance charts or manual flight computers only requires knowledge of the pressure altitude and the air temperature (Guinn and Barry 2016). Most introductory pilot training manuals do not address the impact of humidity.…”

Section: B Damentioning

confidence: 99%

“…In fact, much of aviation literature (FAA 1975(FAA , 2014U.S. Air Force 1997;FAA 2016) does not address the impact of dewpoint temperature on DA calculations at all (Guinn and Barry 2016). However, the importance of accurate calculations of DA is deemed such an integral part of flight planning that moist DA must be considered.…”

Section: B Damentioning

confidence: 99%

See 2 more Smart Citations

Assessing Aircraft Performance in a Warming Climate

McRae

Lee

Galgano

2021

Weather, Climate, and Society

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Increases in maximum and minimum air temperatures resulting from anthropogenic climate change will present challenges to aircraft performance. Elevated density altitude (DA) reduces aircraft and engine performance and has a direct impact on operational capabilities. The frequency of higher DA will increase with the combination of higher air temperatures and higher dew point temperatures. The inclusion of dew point temperature in DA projections will become increasingly critical as minimum air temperatures rise. High DA impacts aircraft performance in the following ways: reduction in power because the engine takes in less air; reduction in thrust because a propeller is less efficient in less dense air; reduction in lift because less dense air exerts less force on the airfoils. For fixed wing aircraft the performance impacts include decreased maximum takeoff weight and increased true air speed which results in longer takeoff and landing distance. For rotary wing, the performance impacts include reduced power margin, reduced maximum gross weight, reduced hover ceiling and reduced rate of climb. In this research, downscaled and bias corrected maximum and minimum air temperatures for future time periods are collected and analyzed for a selected site: Little Rock Air Force Base, Arkansas. Impacts corresponding to DA thresholds are identified and integrated into risk probability matrices enabling quantifiable comparisons. As the magnitude and frequency of high DA occurrences are projected to increase due to climate change, it is imperative for military mission planners and acquisition officers to comprehend and utilize these projections in their decision making processes.

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Section: B Damentioning

confidence: 99%

Section: B Damentioning

confidence: 99%

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Assessing Aircraft Performance in a Warming Climate

McRae

Lee

Galgano

2021

Weather, Climate, and Society

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“…The effects of humidity in the atmosphere were not taken into account during the measurements. According to Guinn and Barry (2016), this can cause the error in glide angle up to 2 per cent maximally for the conditions during the testing.…”

Section: Aerodynamics Of the Paraglidermentioning

confidence: 99%

Identification of a degradation of aerodynamic characteristics of a paraglider due to its flexibility from flight test

Kulhánek

2019

AEAT

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Purpose Aerodynamics of paragliders is very complicated aeroelastic phenomena. The purpose of this work is to quantify the amount of aerodynamic drag related to the flexible nature of a paraglider wing. Design/methodology/approach The laboratory testing on scaled models can be very difficult because of problems in the elastic similitude of such a structure. Testing of full-scale models in a large facility with a large full-scale test section is very expensive. The degradation of aerodynamic characteristics is evaluated from flight tests of the paraglider speed polar. All aspects of the identification such as pilot and suspension lines drag and aerodynamics of spanwise chambered wings are discussed. The drag of a pilot in a harness was estimated by means of wind tunnel testing, computational fluid dynamics (CFD) solver was used to estimating smooth wing lift and drag characteristics. Findings The drag related to the flexible nature of the modern paraglider wing is within the range of 4-30 per cent of the total aerodynamic drag depending on the flight speed. From the results, it is evident that considering only the cell opening effect is sufficient at a low-speed flight. The stagnation point moves forwards towards the nose during the high speed flight. This causes more pronounced deformation of the leading edge and thus increased drag. Practical implications This paper deals with a detailed analysis of specific paraglider wing. Although the results are limited to the specific geometry, the findings help in the better understanding of the paraglider aerodynamics generally. Originality/value The data obtained in this paper are not affected by any scaling problems. There are only few experimental results in the field of paragliders on scaled models. Those results were made on simplified models at very low Reynolds number. The aerodynamic drag characteristics of the pilot in the harness with variable angles of incidence and Reynolds numbers have not yet been published.

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“…After completing the integration and solving for ℎ, we obtain the equation for DA height (ℎ ). A more detailed derivation of the DA equation can be found in Guinn & Barry (2016).…”

Section: Basis Of Altimetry Equations: the Hydrostatic Equationmentioning

confidence: 99%

Quantifying the Effects of Humidity on Density Altitude Calculations for Professional Aviation Education

Cited by 7 publications

References 5 publications

Assessing Aircraft Performance in a Warming Climate

Assessing Aircraft Performance in a Warming Climate

Identification of a degradation of aerodynamic characteristics of a paraglider due to its flexibility from flight test

Quantitative Examination and Comparison of Altimetry Rules-of-Thumb for General Aviation

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