View a full description of this report. The following text was automatically extracted from the image on this page using optical character recognition software:. Curves in figure 14 represent the profile-drag coeffi- cient at CL values of 0. FURa:s Propellerresearch-tunnel value from reference 3.
Variable- densIty-tunnel value from reference 6. Theoretical value from reference 5. The reference for gaging the precision of wind-tunnel airfoil results should be the characteristics which the specified airfoil would have in flight at the particular Reynolds Number. Wind-tunnel results would then include accidental errors of measurement, errors in the application of wind-tunnel interferences, and variations of the characteristics due to differences in airfoil accuracy and turbulence.
If the turbulence is considered as a parameter with which characteristics vary rather than as a source of error in precision, the. This attitude has been adopted in considering the accuracy of the results found in this investigation.
The exactness with which the final precision may be predicted depends upon the thoroughness with which the following factors are known: a Regularity and accuracy in measuring air- stream velocity and angularity.
In these tests, however, the strong tripod type of construction used in the airfoil supports and the relatively short cantilever section reduced deflections to negligible amounts. Errors from this source may therefore be disregarded. It was found impossible to evaluate the loss in precision due to differences between the specified and measured airfoil ordinates.
Variable-density-tunnel tests have shown that small errors in the nose profile of model airfoils are quite critical, while differences farther back along the chord are not of great impor- tance. From an examination of table I, it may be seen that the airfoils were not constructed exactly in accordance with the specified ordinates, and that there were small differences between measured and specified ordinates at the airfoil nose; the surfaces, however, were fair in all cases.
The lack of any serious system- atic disagreement in the results from the several airfoils indicates that errors from this source were not large enough to be significant. The experimentally derived values of wind-tunnel and support interference were subject to the same accidental and inherent errors as the tests proper, but these errors would have only a secondary effect on the final results.
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If that doesn't help, please let us know. Unable to load video. Please check your Internet connection and reload this page. If the problem continues, please let us know and we'll try to help. An unexpected error occurred. Airfoils come in many geometries, but they are all described by the same features. The leading edge is the point at the front of the airfoil with maximum curvature. And similarly, the trailing edge is the point of maximum curvature at the back of the airfoil.
The chord line is a straight line connecting the leading and trailing edges. The chord length, c, is the length of this chord line and is used to describe the dimensions in other directions as percentages of the chord length. At various angles of attack, the airfoil generates lower pressures on the upper surface and higher pressures on the bottom surface with respect to the approaching air pressure. According to Bernoulli's Principle, this pressure difference is a result of differences in velocity between the upper and lower regions of the airfoil, which are caused by air molecules interacting with the curved surfaces.
The lower pressure region on the upper surface has a higher velocity than the higher pressure region on the lower surface. If the shear forces parallel to the surface of the airfoil are neglected, then the overall pressure force is what generates lift.
We can define the pressure coefficient, Cp, for an arbitrary point on the airfoil using this relationship. The pressure coefficient is a non-dimensional number, which describes the relative pressures throughout a flow field. P is the absolute pressure, P infinity is the free-stream pressure, and rho infinity and V infinity are the free stream density and velocity, respectively.
Except for leading edge locations, the pressure force directions determined by Cp, approximately point upward in the same direction as lift at low angles of attack. Thus, we can calculate a non-dimensional lift coefficient, CL, which relates generated lift to the fluid flow around the object using this relationship. Here, c is the chord length and x is the horizontal coordinate position with zero as the leading edge. In this experiment, we will analyze the pressure distribution on the surface of an airfoil, which has 19 pressure taps on its surface.
Each of the pressure readings are measured using a liquid manometer. You will measure the pressure distribution and lift by subjecting the airfoil to airflow in a wind tunnel at various angles of attack.
Clark Y-14 Wing Performance: Deployment of High-lift Devices (Flaps and Slats)
For this experiment, you will use an aerodynamic wind tunnel with a test section of 1 ft by 1 ft and a maximum operating air speed of mph. The model airfoil is an aluminum Clark Y airfoil with 19 built-in ports for pressure tubes. The locations of the pressure ports are shown here. The port coordinate is determined by dividing the location of the port by the chord length. The pressure ports are connected to a manometer panel filled with colored oil but marked as water-inch graduations.
To begin, remove the top cover of the test section and install the airfoil vertically on the turntable, making sure that port number one is facing upstream. Replace the top cover of the test section. Note that the airfoil model is touching both the floor and ceiling of the wind tunnel test section in order to make sure there is no 3D flow developed around the airfoil.
Connect the 19 labeled pressure tubes to the corresponding ports of the manometer. Now rotate the turntable for the angle of attack to be zero. Then, turn on the wind tunnel and set the wind speed to 90 mph. Record all 19 manometer height readings in your notebook.
Then, turn the wind tunnel back on with the wind speed at 90 mph and record the manometer readings for each of the 19 pressure ports. Like before, record all manometer readings.Log In. Cheers Greg Locock New here? Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
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Promoting, selling, recruiting, coursework and thesis posting is forbidden. Students Click Here. Related Projects. But sadly xfoil is no good for the ridiculous alpha figures, although having said that my rotor design doesn't use ridiculous alpha so i should be ok Cheers Greg Locock New here? Greg, If you're still after some high AoA figures, you can explore the subject of wind turbines a little and find data for common airfoils at ALL angles of attack.
The reports are "googlable" but if your searches turn up dry, I have links and PDF's at home. Red Flag This Post Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework. This white paper discusses how the rapid introduction of new technologies and the influx of automotive start-ups into the market has led to a multitude of challenges for harness development.
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An unexpected error occurred. First, recall that lift is an aerodynamic force that is generated by a pressure differential between the top and bottom surfaces. The total lift is proportional to the surface area of the wing. Thus, a higher surface area results in increased lift. Lift is also affected by the geometry of the wing cross section, called an airfoil.
Recall that the chord line of the airfoil connects the leading and trailing edges. Another property called the camber describes the asymmetry between the two surfaces.
The majority of wings have positive camber, meaning that they are convex. As with surface area, increased camber results in increased lift. Since wind speed is relatively slow during takeoff and landing, surface area and camber are increased by deploying devices on the wing's leading and trailing edges in order to generate sufficient lift.
The device at the leading edge of the airfoil is called a slat, while the device at the trailing edge is called a flap. Slats and flaps can move into or out of the wings as needed.
While the deployment of slats and flaps increases lift, it also increases the drag force on the aircraft, which acts in opposition to lift. We can quantify both of these forces by calculating the lift coefficient and drag coefficient as shown, where L and D are lift and drag, respectively. Rho infinity and V infinity are the free stream density and velocity, while S is the reference area of the wing.
Lift, as a distributive force in nature, can be equalized or simplified into a single concentrated force located at the center of pressure. However, as the angle of attack changes, this location moves forward or aft. So instead, we refer to the aerodynamic center of the wing when discussing forces.View a full description of this report.
The following text was automatically extracted from the image on this page using optical character recognition software:. Force tests were made with the slot fixed open under various conditions, and also with the slot closed and faired with "Plasticine. Tests were made also at a few intermediate angles of attack, in order to determine the shapes of the lift and drag curves. The tests were made at a dynamic pressure of The IReynolds Number based on the above test conditions and the wing chord of 10 inches waswhich is about one-third of that for an ordinary small airplane while landing.
The angle-of-attack setting was accurate to 0.Hot Wire Aerofoil Template PDF - Club AeroFlutter
A comparison of the results of check tests showed the variation between values of the maximum lift to be about 1 per cent; the variation between the minimum drag values amounted to about 2 per cent.
Choice of the probable best slot arrangement. Reference 2. In that investiga- tion the auxiliary airfoil was tested at different locations with respect to the main wing.
Tables I to V, inclusive, give the results of those tests in the form of coefficients of maximum lift and minimum drag, angle of attack for maximum lift, and ratio of maximum lift coefficient to minimum drag coefficient for each slot arrangement.
All the above four items were considered in the selec- tion of the best slot arrangement for a wing with a fixed slot. The maximum lift coefficient and angle of attack for maximum lift determine the landing speed and stalling angle, respectively, of the airplane. The minimum drag coefficient is a measure of the high speed attainable, and the ratio of maximum lift to minimum drag gives an indication of the speed range possible.
Tne conditions chosen, which of necessity were a compromise, may be found in Table II. The location of the auxiliary airfoil with respect to the main wing for the above conditions is shown to scale in the above-mentioned figure. The ordinates for the auxiliary airfoil No. Effect of auxiliary airfoil shape and position. This edge was rounded and the auxiliary air- foil then had the shape shown in Figure lb, the ordi. The slot arrangement was kept as near like that of the wing with auxiliary airfoil No.
Show all pages in this report. This report can be searched. Note: Results may vary based on the legibility of text within the document. Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding. Weick, Fred E. You Are Here: home unt libraries government documents department this report page: 6.
These controls are experimental and have not yet been optimized for user experience. Reset Brightness 0. Reset Contrast 0. Reset Saturation 0. Reset Sharpness 0. Reset Exposure 0. Reset Hue 0.The Clark Y is an airfoil widely used in aircraft wing design.
CLARK-Y 11.7% smoothed (clarkysm-il)
The airfoil has a flat bottom shape that makes for easy building directly on your construction board. I have employed the Clark Y for all my model plane designs. Drawing an airfoil is not hard. You can use the ordinate method described below to draw a Clark Y airfoil. An alternative approach is to use TurboCAD. A significant advantage of the TurboCAD method is that you can quickly draw versions of the Clark Y rib shape for any size design you might prepare in the future. Selecting an airfoil is a crucial design decision.
Airfoil Behavior: Pressure Distribution over a Clark Y-14 Wing
Airfoils vary from a symmetrical shape, typically used with aerobatic aircraft to the use of a flat wing. Flat wings are used with lightweight 3D indoor flyers. Their flight performance is excellent due to their small size and high thrust to weight ratios. The motor power actually exceeds the weight of the aircraft. The Clark Y is an ideal choice for a wide range of RC models. The Clark Y has reasonably high camber.
This allows for an efficient lift to drag ratio on a typical sport RC flyer. Airplanes flown in the first decade of flight often had a highly under cambered airfoil shape. With an under cambered airfoil you can clearly see the inward curvature on the underside of the wing. An under cambered airfoil can be usefully employed for lighter weight RC models of antique aircraft. As an example, I used the top outline of a Clark Y airfoil for under cambered airfoil of my Blackburn Type D monoplane desig n.
An under cambered wing cross section usually does not have sufficient depth for the structural wing spars. To maintain wing strength the designer has two choices. You can either use a deeper wing section to embed the spars or employ functional wing to fuselage rigging wires.
The Clark Y shape was developed in the early s by Mr. Virginius Clark. The flat bottom permits easy wing construction as the wing ribs are pinned directly onto the building board.
This building approach certifies a warp free wing.