@article{oai:jaxa.repo.nii.ac.jp:00035230,
 author = {TAMARU, Takuro},
 issue = {1},
 journal = {東京帝國大學航空研究所報告, Report of Aeronautical Research Institute, Tokyo Imperial University},
 month = {Feb},
 note = {This instrument makes use of the dependence of the pressure at any point of a cylinder against which the wind blows, on the azimuth of the point measured from the direction from which the wind comes, and records a difference or differences of pressure for different azimuths. The actual cylinder has a diameter 1.24cm., and has two or three rows of three or four small holes each, the rows being parallel to the axis of the cylinder. The space inside the cylinder is separated longitudinally, so that each row of holes has its own space from which a side tube allows connection with a pressure measuring instrument. My first instrument had a tube with two rows of holes, and as the pressure-meter an ordinary aneroid with certain modifications. It was intended to measure directly the angle of side-slip when the aeroplane makes a horizontal turn or a steep descent with side-slip, the velocity of the aeroplane relative to the air being assumed as known. This instrument was tried on an aeroplane "Avro" in flight, and was found to work as satisfactorily as could be expected. When the azimuthal angle is considerable, however, the knowledge of the magnitude of velocity, as measured by a fixed pitot-tube can not be said to be exact enough. So I proceeded to work out the principle of a registering instrument, from which the direction and velocity of the wind (in a longitudinal plane fixed to the aeroplane, which may be, in the normal position of the latter, ofther horizontal or vertical) relative to the aeroplane can be determined. The range of direction covers an angle of 120°; e.g. when set for up-and-down angles, for any angle of attack between -20°and 100°. This will include the case an aeroplane recovers suddenly from a vertical dive. The instrument registers directly two differences of pressure, P_1 and P_2, of three rows of holes. The middle set of holes B makes an angle of 30°with those on the sides A and C. Thus, P_1=PA-PB, P_2=PB-PC. The method of registering is the same as in an ordinary barograph. The inside spaces of two piles of elastic boxes are separately connected to the sets of holes on the sides A and C, while the chamber of the barograph made airtight is connected to the middle set B. A preliminary examination with tubes of diameter 0.91 and 1.27cm. and wind velocity 18.4 and 25.8 m/sec. resp. in a wind tunnel gave the "reduced" negative pressure Pr as a function of azimuth φ, as shown in fig. 10 (p.11) and Table 1 (p.12), this being the value of P measured from that for φ=0, and where the "amplitude" i. e. the difference between the maximum and minimum of pressure is taken as unity; thus, Pr=(P-P_0)/ampl. From this, denoting the azimuth of B by θ, I have calculated the numbers for [numerical formula], and [numerical formula], as shown in the columns (1) and (2) of Table 11 (p.13). On calculating [numerical formula]., I find values nearly equal to unity for all values of θ (column (7) of the same Table); and further, (P_2+P_1)/(P_2-P_1) and (P_2-P_1)/(P_2+P_1) are found to be well suited for determination of θ (columns (8) and (9)). Hence, as the values of P_1 and P_2 are registered by the instrument, the values of θ and ρV^2 (ρ, the density of air; V, the velocity of wind) can be found thus:- [numerical formula] by making use of Table III or fig. 12 (pp.16, 17). [numerical formula], where k is a constant giving the ratio ρV^2/amplitude, and F(θ) is the reciprocal of the numbers under (7) of Table II and is given by Table IV and fig. 13 (p.17). k has, so far as I can see with the small wind tunnel at my disposal, a value near unity; its more exact value has still to be determined. The approximate relations [numerical formula] [numerical formula] suggest a graphical method of finding ρV^2 and θ from P_2-P_1 and P_2+P_1. If we have a diagram provided with lines of constant P_2-P_1, P_2+P_1, θ and ρV^2 (or V, if ρ is considered constant) as in fig. 14 (p.19), we can read at once from it the values of θ and ρV^2 (or V) corresponding to any set of values of P_2-P_1 and P_2+P_1. They further suggest the possibility of an instrument which gives directly the values of V (for a given ρ) and θ. If we have two such instruments, one of which has its cylinder vertical and the other horizontal and transverse, we get four numbers, which are equivalent to the three component velocities of the wind, the forward velocity being given separately from each instrument and serving as a check. For use in a fixed place, as in a wind tunnel, we can use along with the cylinder with rows of holes, one or two water manometers, instead of the aneroid or the barograph., 資料番号: SA4146373000},
 pages = {1--23},
 title = {Hikoki ni taisuru Kaze no Hoko to Hayasa wo kirokusuru Kikai},
 volume = {1},
 year = {1921}
}