US2636280A

US2636280A - Propeller template

Info

Publication number: US2636280A
Application number: US789260A
Authority: US
Inventors: Vasili S Drake
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-12-02
Filing date: 1947-12-02
Publication date: 1953-04-28
Anticipated expiration: 1970-04-28

Description

April 1953 v. s. DRAKE PROPELLER TEMPLATE Filed Dec. 2, 1947 Fig.4

INIfEZNTOR. Vaslll .5. Brake Fig.3

Fig.2

Attorney Patented Apr. 28, 1953 UNITED STATES PATENT OFFICE 2,636,280 PROPELLER TEMPLATE VasililS. Drake, San Diego, slalif.v

Application Decemher 2, 1947, Serial No. 789,260

(Granted under Title 35, U. S. Code (1952),

sec. 266) 4 Claims.

This invention relates to propeller blade templates, and more particularly to an adjustable template which may be employed in the checking of practically all types of propeller blades.

In the fabrication and repair of propeller blades it is essential that the pitch of the blade at various points along the length thereof be determined accurately. This Operation is performed, on a demounted propeller, by securing thepropeller to a table, with the propeller shaft vertical and the blade to be checked extending over and above the surface of the table. A pro tractor is then positioned a predetermined distance away from the shaft axis, and the inclination of the propeller surface, on a line normal to the blade axis, is measured. This inclination, known as propeller pitch, is measured at prede termined radii from the propeller shaft, in accordance with a standard table established by the propeller designer.

When the under face, i. e. that facing the table, of the blade is formed of a straight line generatrix, a simple protractor having a straight abutting edge may be used. When, however, the under face of the plate is curved in accordance with air foil considerations, means must be interposed between the protractor straight edge and the propeller face to insure that the protractor edge will be exactly parallel to a line through the center of the propeller section.

It is an object of the instant invention to provide a template which maybe positioned against a propeller blade to derive a straight edge which will be exactly parallel to the center line of the propeller section, and which may be used on propellers having differing contours.

It is another object of this invention to provide a universal template which may be used in pitch measurements of practically all types of propellers manufactured.

It is a further object of this invention to provide a template of simplified and rugged construction which may be mountedon a protractor for pitch measurement of practically any type of propeller.

In accordance with the instant invention, the template is constructed having three points of abutment against a propeller, thereby providing positive yet unambiguous positioning of the template against the propeller. Two of the points are relatively fixed and permanent; the third point is variable, thereby adapting the template for use with practically any known type of propeller. This third abutment point is part of an adjustable abutment holder which is so through one of the plates 23.

dices 28 are marked along the barl3 cooperable' mounted on the template that the third abutment point has two degrees of adjustability, i. e. may be adjusted both longitudinally and transversely of the template.

'I'wo exemplary embodiments of the instant invention will now be described with reference to the accompanying drawing, wherein:

Fig. .1 shows a first embodiment of the instant template mounted on a protractor and applied to a propeller. Fig. 1 is taken generally along line. l-l of Fig. 2;

Fig. 2 is a plan view showing more generally how the template is applied to the propeller;

Fig. 3 is an enlarged detailed View, showing an alternative type of abutment member constituting the third or variable abutment surface; andv Fig. 4 is a section taken along line l4 of Fig. 8.

Referring to the drawing, H designates the cross section of a propeller blade, against which pressed the template 12, comprising a bar It having at one end thereof a transverse abutment post it forming an abutment surface for the leading edge l5 of the propeller II. A second abutment surface or point is formed of a button 16 mounted at the edge of a step portion I? positioned at the intersection of the bar 13 and the post 14. If desired, the parts l3, M, and I? may be made integral, although it is preferred to form the button It of a separate piece so that it may be fabricated to closer tolerance.

The two points of abutment thus described require only a third abutment point, spaced there from, to assure that the template may be placed in positive yet unambiguous position against the propeller il. In the Fig. 1 embodiment this third point is provided by a-cam 2| fixed to ashaft 22 journaled between a pair of plates 23 which embrace the bar I3 and constitute a slider 24 longitu dinally adjustable along the bar. The plates 23 protrude transversely above and below the bar l3,

Slider 24 may be moved back and forth along the barl3 and locked in pre-selected position by means of a set screw or locking screw 21 threaded Transverse inwith one of the edges, e. g. edge 29, of the slider 24 to aid in positioning the slider along the bar. One degree of positioning of the abutment point 26, i. e. longitudinally of the bar [3, is thus determined.

The other degree of positioning of the abutment point 26, i. e. transversely of the bar I3, is determined in discrete steps by the provision of a series of recesses 3| in the outer surface of one of the plates 23, disposed circumferentially adjacent the end of the crank 25, which is provided with a suitable form of spring pressed detent (not shown) engageable in the recesses 3|.

The lower protruding portions 33 of the plates 23 constitute a bifurcated bracket, which may be fitted over a protractor bar 34 and firmly afiixed thereto by a set screw 35, threaded through one of the plates 23. A similar mounting arrangement is provided adjacent other end of thebar l3 in the form of a pair of mounting plates 36 fixedly secured to the bar l3 and embracing the protractor bar 34, to which they may be selectively locked by a set screw 31.

Operation The manner of use of the protractor illustrated in Fig. 1 will now be described, with reference to Figs. 1 and 2.

The propeller 4| to be checked is mounted with its shaft 42 vertical and with one of the blades ll extending over the surface of a table 43. At a predetermined radius from the shaft 42, determined by the specifications of the propeller designer, the template I2 is positioned beneath the blade ll. Prior to this step the slider 24 has been locked by set screw 21 at the proper index 28, as prescribed by the propeller designer. Likewise, the end of the crank 25 has been set in the proper recess 3 I, pursuant to designers requirements, thus placing the upper surface of the cam 2| as predetermined distance from the bar [3. The third abutment point 26 has thus been disposed, in accordance with the requirements of the propeller designer, so that for the particular propeller ll being measured, the section center line 44 of the propeller II will be, when all three abutment points are engaged, exactly parallel to the protractor bar 34, when the template [2 is mounted thereon.

After positioning the template l2 against the propeller II, the operator moves the protractor 45, including its protractor bar 34, into position and clamps it to the template I2, now employing the set screws and 31, Height adjustability of the protractor above the table 43 may be accommodated by suitable means such as telescoping of the protractor standard as shown at 46. The blade H is then checked at each of the several prescribed radii, the transverse and longitudinal settings of the abutment point 26 being varied as specified.

The blade I I may be, and is generally, checked while mounted to the airplane. The instant device is equally suitable for such operation. In this case a protractor adapted for use on a mounted propeller is employed. An example of such a protractor is illustrated in Whitechester Patent 2,383,527. The instant template is inserted between the straight edge of the Whitechester protractor and the curved blade contour, in a manner similar to that described immediately above.

Modification The manner for achieving transverse adjustability of the point 26 shown in Fig. 1 is only one of several suitable arrangements that may be employed. Another satisfactory way of achieving the same result is shown in Figs. 3 and 4, wherein the shaft 22' of the slider 24' has mounted thereon a spoke-like abutment member 5|, each of the arms 52 of which has a different length, thereby providing a series of differing transverse spacings for the abutment point 26.

As shown in Fig. 4 the shaft 22 is conveniently rotated by means of a crank 25', and is locked in preselected position by a knurled lock nut 53. The plates 23' of the slider 24' are secured together in position embracing the bar 13 by a pair of

spacers

54 and 55, the bottom of the latter being the surface providing a seat for the template l2 against the protractor bar 34. It will be understood that the slider 24 of Fig. 1 appears in cross section much as shown in Fig. 4 for the slider 24'.

From the above description it will be seen that there has been described a template for the checking of propeller blade pitch having practically universal application to all types of airplane propellers.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

l. A propeller blade template comprising a bar having abutment means adjacent one end thereof against which a propeller blade may abut, a slider slidable along said bar, said slider being comprised of a pair of plates embracing said bar and protruding transversely therefrom and means connecting said plates to hold the slider to said bar, a shaft extending through a protruding portion of said plates, and an abutment cam mounted on said shaft and rotatable about the axis thereof, whereby one end of said bar may be spaced at selectively differing distances from the blade.

2. A propeller blade template comprising a bar having abutment means adjacent one end thereof against which a propeller blade may abut, a slider slidable along said bar, said slider including a pair of plates embracing said bar and protrucling transversely from each side thereof and means connecting said plates to hold the slider to said bar, a shaft extending through a protruding portion of said plates, a non-circular abutment member rotatably mounted on said shaft in edgewise relation thereto and having a plurality of points on its periphery adapted to bear against the blade and spaced at differing radii from said 7 screw threaded thru one of said plates and operable to lock said slider in selected position along said bar, a shaft extending through a protruding portion of said plates, an abutment cam mounted on said shaft and rotatable about the axis thereof, whereby one end of said bar may be spaced at selectively differing distances from the blade, means for locking said abutment cam in selected position to said slider, and a set screw threaded thru the other protruding portion of one of said plates for securing said bar to a protractor.

4. A propeller blade template comprising a, bar having means adjacent one end constituting a two pointabutment for a propeller blade to be measuredQa slider comprised of two plates circumjacent said bar with cross members securing said plates; together and permitting sliding movement of said slider along said bar. a set screw threadedthru said slider for clamping said slider to said bar at selected points, a shaft extending between said plates, a cam mounted on said shaft between said plates and rotatable about-the shaft axis, a crank on one end of said shaft having a detent pressed toward the adjacent plate, and a series of circumferentially spaced recesses adjacent said detent for providing discrete positioning points for said arm, and hence for said cam.

VASILI S. DRAKE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 412,984 Schmidt Oct. 15, 1889 10 1,206,060 Warner Nov. 28, 1916 1,213,134 Fellows Jan. 16, 1917 1,509,703 Bourgeois Sept. 23, 1924 1,637,921 Simpson Aug. 2, 1927 1,736,247 Bodenlos Nov. 19, 1929 15 1,896,926 Von Frommer Feb. 7, 1933 2,238,782 Roche Apr. 15, 1941 2,343,802 Radney Mar. 7, 1944 2,358,987 MacKay Sept. 26, 1944 2,402,567 Milner June 25, 1946 20 2,402,715 Warner June 25, 1946 FOREIGN PATENTS Number Country Date 293,249 Germany July 24, 1916