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Search Results (6)

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Authors = Lance W. Traub ORCID = 0000-0002-8258-362X

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16 pages, 6066 KiB  
Article
Effect of Gurney Flaps on Non-Planar Wings at Low Reynolds Number
by Lance W. Traub
Aerospace 2024, 11(9), 728; https://doi.org/10.3390/aerospace11090728 - 6 Sep 2024
Viewed by 1052
Abstract
The effect of spanwise wing non-planarity, employed in conjunction with a Gurney flap, is presented. Testing was undertaken in a low-speed wind tunnel using a rectangular wing with an aspect ratio of three. The outer one-third of the wing was non-planar, which took [...] Read more.
The effect of spanwise wing non-planarity, employed in conjunction with a Gurney flap, is presented. Testing was undertaken in a low-speed wind tunnel using a rectangular wing with an aspect ratio of three. The outer one-third of the wing was non-planar, which took the form of either dihedral or a circular arc. A 2% high Gurney flap was implemented such that it could extend over the entire span or the planar inboard section. The loads were measured using a sting balance. The data show that non-planarity increases the maximum lift coefficient and the wing’s lift curve slope. Gurney flap lift modulation was enhanced in the presence of non-planarity. The addition of Gurney flaps caused a greater increment in the minimum drag coefficient for the non-planar wings. The Gurney flaps reduced the lift-dependent drag of the wings. As a whole, the Gurney flaps reduced the maximum lift-to-drag ratio (L/D)max for the non-planar wings; however, the flat wing exhibited a small L/D increment with flap addition. Full article
(This article belongs to the Section Aeronautics)
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20 pages, 3975 KiB  
Article
Wing Efficiency Enhancement at Low Reynolds Number
by Lance W. Traub
Aerospace 2024, 11(4), 320; https://doi.org/10.3390/aerospace11040320 - 19 Apr 2024
Viewed by 2441
Abstract
The aerodynamic performance of wings degrades severely at low Reynolds number; lift often becomes non-linear, while drag increases significantly, caused by large extents of separation. Consequently, a non-conventional wing design approach is implemented to assess its ability to enhance performance. The design methodology [...] Read more.
The aerodynamic performance of wings degrades severely at low Reynolds number; lift often becomes non-linear, while drag increases significantly, caused by large extents of separation. Consequently, a non-conventional wing design approach is implemented to assess its ability to enhance performance. The design methodology is that of wing segmentation, where the wing is divided into spanwise panels that can be separated, thereby yielding small gaps between the panels. A moderate aspect ratio wing comprised of four separate wing panels was manufactured and wind tunnel tested through a Re range from 40,000 to 80,000. Force balance data and surface flow visualization were used to characterize performance. The results indicate that segmentation is effective in significantly augmenting efficiency at Reynolds numbers at which the fused wing (i.e., no gaps) shows large extents of open separation. Drag is greatly reduced, while lift is increased, and stall is delayed. The benefit of segmentation was noted to diminish at higher Re where the fused wing’s performance improves markedly. Wing segmentation could find application in micro-unmanned-aerial-vehicle and drone design. Further study would entail the effects of AR and the number of spanwise panels on performance. Full article
(This article belongs to the Section Aeronautics)
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10 pages, 1527 KiB  
Communication
Examination and Prediction of the Lift Components of Low Aspect Ratio Rectangular Flat Plate Wings
by Lance W. Traub
Aerospace 2023, 10(7), 597; https://doi.org/10.3390/aerospace10070597 - 30 Jun 2023
Cited by 4 | Viewed by 2362
Abstract
An investigation of the lift components present over low aspect ratio rectangular wings is presented. Wing aspect ratios ranging from 0.5 to 3 are examined using published experimental results and analytic analysis methods. The methods are based on the fundamental decomposition of Polhamus; [...] Read more.
An investigation of the lift components present over low aspect ratio rectangular wings is presented. Wing aspect ratios ranging from 0.5 to 3 are examined using published experimental results and analytic analysis methods. The methods are based on the fundamental decomposition of Polhamus; that is, lift is attributed to a potential flow lift component coupled with a vortical lift component stemming from the leading and side edges of the flat plate wing. The analysis suggests a low sensitivity to Reynolds numbers spanning three orders of magnitude and brings into doubt the realization of a leading edge vortex lift component for wings with unswept leading edges under steady state conditions. The analytic prediction method of Purvis is shown to provide close accord with all experimental data sets when lift contributions caused by a leading edge vortex are excluded. Full article
(This article belongs to the Section Aeronautics)
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9 pages, 9912 KiB  
Communication
Effect of Leading-Edge Slats at Low Reynolds Numbers
by Lance W. Traub and Mashaan P. Kaula
Aerospace 2016, 3(4), 39; https://doi.org/10.3390/aerospace3040039 - 17 Nov 2016
Cited by 11 | Viewed by 19671
Abstract
One of the most commonly implemented devices for stall control on wings and airfoils is a leading-edge slat. While functioning of slats at high Reynolds number is well documented, this is not the case at the low Reynolds numbers common for small unmanned [...] Read more.
One of the most commonly implemented devices for stall control on wings and airfoils is a leading-edge slat. While functioning of slats at high Reynolds number is well documented, this is not the case at the low Reynolds numbers common for small unmanned aerial vehicles. Consequently, a low-speed wind tunnel investigation was undertaken to elucidate the performance of a slat at Re = 250,000. Force balance measurements accompanied by surface flow visualization images are presented. The slat extension and rotation was varied and documented. The results indicate that for small slat extensions, slat rotation is deleterious to performance, but is required for larger slat extensions for effective lift augmentation. Deployment of the slat was accompanied by a significant drag penalty due to premature localized flow separation. Full article
(This article belongs to the Collection Unmanned Aerial Systems)
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7 pages, 1229 KiB  
Communication
Calculation of Constant Power Lithium Battery Discharge Curves
by Lance W. Traub
Batteries 2016, 2(2), 17; https://doi.org/10.3390/batteries2020017 - 11 Jun 2016
Cited by 29 | Viewed by 21178
Abstract
Standard battery testing procedure consists of discharging the battery at constant current. However, for battery powered aircraft application, consideration of the cruise portion of the flight envelope suggests that power should be kept constant, implying that battery characterization should occur over a constant [...] Read more.
Standard battery testing procedure consists of discharging the battery at constant current. However, for battery powered aircraft application, consideration of the cruise portion of the flight envelope suggests that power should be kept constant, implying that battery characterization should occur over a constant power discharge. Consequently, to take advantage of existing battery discharge curves it would be useful to have a methodology that can extract a constant power discharge curve from a constant current discharge curve. The development of such a methodology for lithium batteries is described in this article. Full article
(This article belongs to the Special Issue Lithium Ion Batteries)
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8 pages, 721 KiB  
Communication
Semi-Empirical Prediction of Airfoil Hysteresis
by Lance W. Traub
Aerospace 2016, 3(2), 9; https://doi.org/10.3390/aerospace3020009 - 24 Mar 2016
Cited by 11 | Viewed by 10550
Abstract
A semi-empirical method is presented to estimate the angular excursion and the lift loss associated with static hysteresis on an airfoil. Wind tunnel data of various airfoils is used to define and validate the methodology. The resulting equation provides a relationship between the [...] Read more.
A semi-empirical method is presented to estimate the angular excursion and the lift loss associated with static hysteresis on an airfoil. Wind tunnel data of various airfoils is used to define and validate the methodology. The resulting equation provides a relationship between the size of the hysteresis loop and characteristics of the airfoil. Comparisons of the equation with experiment show encouraging agreement both in terms of the magnitude of the lift loss and the extent of the loop. Full article
(This article belongs to the Special Issue Feature Papers in Aerospace)
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