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Correspondence

Correspondence To the Editor DEAR SIR, I agree with Professor Argyris and Mr Kochan- Total Pressure Probes - Kinetic Heating of Thin Wings ski, that the hypothesis that the shortening of the projected distance between the end points is parabolic, as indicated by Eq. 4 of Ref. (12), indeed makes the virtual displacement FIG. 3 illustrates the time response presented To the Editor in a manner similar to that used by Winternitz. DEAR SIR, To determine these curves the instrument was The Kiel type probe described by Winternitz* incompatible with the condition of zero out of connected by 10 ft. of 3/32 in. bore flexible tubing can be simplified further with very little sacrifice plane deformations. However this hypothesis is to a manometer 36 in. long and 3/32 in. bore using of tolerance to angles of yaw. The instrument not essential and is just a way of looking at the gauge fluid of specific gravity 2·94. This arrange­ described below, in addition to being simple, is problem. Another point of view would be to ment is typical of that used for hand traversing also robust and suitable for general test house use. assume no shortening but take into account the in ducting models, turbines, etc. Response times FIG. 1 illustrates the construction of the unit. work done by the vertical resultants of the edge were determined by the following procedure: the A ¼ in. diameter rod has a ⅛ in. hole drilled stresses (when the hypothesis of shortened pro­ instrument was connected to the suction side of through on a diameter and an inlet flare is formed jected distance is used there are no vertical com­ the manometer and the flexible tube sealed by a by a 90 deg. countersink as shown. No attempt ponents). The work done by the vertical compo­ clamp at the instrument. By means of a T junction is made to blend the internal corner so formed. nents of the fictitious edge stresses σ during a in the line a suction pressure of the required Although it is possible that a wider tolerance to virtual displacement δk is then (using the nota­ value, e.g. 88·4 in. for 0·6 Mach number, was angles of yaw might be obtained if it were blended tion of Ref. (12)). applied. On releasing the clamp a curve of gauge (see Aerodynamic Measurements by R. C. Dean, reading against time can be obtained and from M.I.T., p. 71) quite satisfactory performance is this the curves shown in FIG. 3 can be constructed. obtained with this simple and easily repeatable A point of interest is that these results were not machining operation. The total pressure is meas­ obtained in a calibration tunnel with actual flow ured by a small cylindrical pitot tube formed by nor was it thought necessary to do so. These drilling a ·020 in. diameter hole in the wall of a curves are considered to represent the case where stainless steel tube ·063 in. outer diameter x the instrument head is contained first within the Hence Eq. (5) of Ref. (12) is obtained without ·041 in. inner diameter and positioning this tube duct wall so that it starts by reading the stream the use of Eq. (4). as shown. The resulting instrument can then be static pressure and is then plunged into the stream, It is, therefore, not surprising that the correct used through a ¼ in. diameter hole in a duct wall. the total pressure always being atmospheric, i.e. result was obtained, even though at an interme­ The characteristics of the instrument are shown in suction tunnel conditions. A few tests were car­ diate stage of the original analysis a viewpoint FIG. 2 where the error in total pressure as a per­ ried out with the instrument flow in the opposite was taken which required a virtual displacement centage of the stream dynamic pressure is plotted direction, e.g. with the gauge line connected to incompatible with the zero out of plane de­ against angle of yaw. There is no error in the the pressure side of the manometer and pressure formations. range ±35 deg. and only ½ per cent error up to being applied so that air flows out of the instru­ I would like to thank Professor Argyris and ±40 deg. Virtually the same curve is obtained at ment to reach equilibrium. No significant differ­ Mr Kochanski for this discussion which brought all Mach numbers up to 0·9, the variation in ences in times were noted, naturally all such out some of the finer points of the analysis. tolerance being of the order of ±1 deg. on the response curves depend on the actual test set-up, curve shown. but FIG. 3 shows that these times are quite low. Yours faithfully, The instrument has also been tested at angles Yours faithfully, DR J. SINGER of pitch up to ±20 deg., the maximum possible on the calibration tunnel used. No error was R. E. MORRIS observed in this range. Department of Aeronautical Engineering, Napier Research Station, Israel Institute of Technology, Haifa. East Lancashire Road, Liverpool 10. • 'Simple Shielded Total Pressure Probes' by F. A. L. Winter­ November]!, 1958 nitz, AIRCRAFT ENGINEERING, Vol. XXX, No. 356, October, 1958. November 11, 1958 8 Aircraft Engineering http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Aircraft Engineering and Aerospace Technology Emerald Publishing

Correspondence

Aircraft Engineering and Aerospace Technology , Volume 31 (1): 1 – Jan 1, 1959

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Publisher
Emerald Publishing
Copyright
Copyright © Emerald Group Publishing Limited
ISSN
0002-2667
DOI
10.1108/eb033066
Publisher site
See Article on Publisher Site

Abstract

To the Editor DEAR SIR, I agree with Professor Argyris and Mr Kochan- Total Pressure Probes - Kinetic Heating of Thin Wings ski, that the hypothesis that the shortening of the projected distance between the end points is parabolic, as indicated by Eq. 4 of Ref. (12), indeed makes the virtual displacement FIG. 3 illustrates the time response presented To the Editor in a manner similar to that used by Winternitz. DEAR SIR, To determine these curves the instrument was The Kiel type probe described by Winternitz* incompatible with the condition of zero out of connected by 10 ft. of 3/32 in. bore flexible tubing can be simplified further with very little sacrifice plane deformations. However this hypothesis is to a manometer 36 in. long and 3/32 in. bore using of tolerance to angles of yaw. The instrument not essential and is just a way of looking at the gauge fluid of specific gravity 2·94. This arrange­ described below, in addition to being simple, is problem. Another point of view would be to ment is typical of that used for hand traversing also robust and suitable for general test house use. assume no shortening but take into account the in ducting models, turbines, etc. Response times FIG. 1 illustrates the construction of the unit. work done by the vertical resultants of the edge were determined by the following procedure: the A ¼ in. diameter rod has a ⅛ in. hole drilled stresses (when the hypothesis of shortened pro­ instrument was connected to the suction side of through on a diameter and an inlet flare is formed jected distance is used there are no vertical com­ the manometer and the flexible tube sealed by a by a 90 deg. countersink as shown. No attempt ponents). The work done by the vertical compo­ clamp at the instrument. By means of a T junction is made to blend the internal corner so formed. nents of the fictitious edge stresses σ during a in the line a suction pressure of the required Although it is possible that a wider tolerance to virtual displacement δk is then (using the nota­ value, e.g. 88·4 in. for 0·6 Mach number, was angles of yaw might be obtained if it were blended tion of Ref. (12)). applied. On releasing the clamp a curve of gauge (see Aerodynamic Measurements by R. C. Dean, reading against time can be obtained and from M.I.T., p. 71) quite satisfactory performance is this the curves shown in FIG. 3 can be constructed. obtained with this simple and easily repeatable A point of interest is that these results were not machining operation. The total pressure is meas­ obtained in a calibration tunnel with actual flow ured by a small cylindrical pitot tube formed by nor was it thought necessary to do so. These drilling a ·020 in. diameter hole in the wall of a curves are considered to represent the case where stainless steel tube ·063 in. outer diameter x the instrument head is contained first within the Hence Eq. (5) of Ref. (12) is obtained without ·041 in. inner diameter and positioning this tube duct wall so that it starts by reading the stream the use of Eq. (4). as shown. The resulting instrument can then be static pressure and is then plunged into the stream, It is, therefore, not surprising that the correct used through a ¼ in. diameter hole in a duct wall. the total pressure always being atmospheric, i.e. result was obtained, even though at an interme­ The characteristics of the instrument are shown in suction tunnel conditions. A few tests were car­ diate stage of the original analysis a viewpoint FIG. 2 where the error in total pressure as a per­ ried out with the instrument flow in the opposite was taken which required a virtual displacement centage of the stream dynamic pressure is plotted direction, e.g. with the gauge line connected to incompatible with the zero out of plane de­ against angle of yaw. There is no error in the the pressure side of the manometer and pressure formations. range ±35 deg. and only ½ per cent error up to being applied so that air flows out of the instru­ I would like to thank Professor Argyris and ±40 deg. Virtually the same curve is obtained at ment to reach equilibrium. No significant differ­ Mr Kochanski for this discussion which brought all Mach numbers up to 0·9, the variation in ences in times were noted, naturally all such out some of the finer points of the analysis. tolerance being of the order of ±1 deg. on the response curves depend on the actual test set-up, curve shown. but FIG. 3 shows that these times are quite low. Yours faithfully, The instrument has also been tested at angles Yours faithfully, DR J. SINGER of pitch up to ±20 deg., the maximum possible on the calibration tunnel used. No error was R. E. MORRIS observed in this range. Department of Aeronautical Engineering, Napier Research Station, Israel Institute of Technology, Haifa. East Lancashire Road, Liverpool 10. • 'Simple Shielded Total Pressure Probes' by F. A. L. Winter­ November]!, 1958 nitz, AIRCRAFT ENGINEERING, Vol. XXX, No. 356, October, 1958. November 11, 1958 8 Aircraft Engineering

Journal

Aircraft Engineering and Aerospace TechnologyEmerald Publishing

Published: Jan 1, 1959

There are no references for this article.