US2259247A - Propeller blade - Google Patents

Propeller blade Download PDF

Info

Publication number
US2259247A
US2259247A US199165A US19916538A US2259247A US 2259247 A US2259247 A US 2259247A US 199165 A US199165 A US 199165A US 19916538 A US19916538 A US 19916538A US 2259247 A US2259247 A US 2259247A
Authority
US
United States
Prior art keywords
blade
tongue
parts
propeller
root
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US199165A
Inventor
Dornier Claude
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Dornier Werke GmbH
Original Assignee
Dornier Werke GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dornier Werke GmbH filed Critical Dornier Werke GmbH
Application granted granted Critical
Publication of US2259247A publication Critical patent/US2259247A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C11/00—Propellers, e.g. of ducted type; Features common to propellers and rotors for rotorcraft
    • B64C11/16—Blades
    • B64C11/20—Constructional features
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64C—AEROPLANES; HELICOPTERS
    • B64C11/00—Propellers, e.g. of ducted type; Features common to propellers and rotors for rotorcraft
    • B64C11/16—Blades
    • B64C11/20—Constructional features
    • B64C11/24—Hollow blades
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49316—Impeller making
    • Y10T29/49332—Propeller making
    • Y10T29/49334—Utilizing hollow tube blank

Definitions

  • PROPELLER BLADE Filed March 51, 193s lllalyem- I "alizee/l y lNVENTOR CLA U05 oE/v/E/e.
  • 'I'he present invention relates to propellers, particularly for aircraft and more specifically to propeller blades which are made up of a plurality of parts which parts may be made of different materials.
  • the present invention is particularly useful in connection with variable pitch propellers the blades of which are made of wood.
  • the blade according to the present ⁇ invention comprises a metal shaft from which a tongue extends into the blade for about one third to two thirds of its length. Tongue and shaft may be longitudinally split into two parts which are held together by suitable connecting means.
  • Figure 1 is a cross sectional view of a propeller blade according to the present invention.
  • Figure 2 is an isometric illustration of the core or tongue member according to the present invention.
  • Figure 3 is a cross sectional view of a modified propeller blade construction according to the present invention.
  • FIG. 4 is an isometric illustration of the split tongue which is used in connection with the construction shown in Figure 3.
  • numerals I and 2 designate the hollow shells which in conventional manner, form the propeller blade proper and may be made of wood, Bakelite or a similar light material.
  • the shells are made of wood and are covered by means of a veneer 4.
  • the interiors of the shells I and 2 are provided with reinforcements 5 and 6 respectively through which bolts 3 extend which hold the shells I and 2 together.
  • the reinforcements may be in the form of longitudinal projections or in the form of a plurality of individuah boss-like projections.
  • a tongue like' member I which is preferably made of metal is provided in the interior of the hollow blade l
  • the body which comprises the tongue mem- (Cl. T10-159) ber 1 is illustrated in Fig. 2. It consists of shaft 8 which is rotund, forged, pressed or cast and which is provided with a reset 25 for mounting the shaft 8 to the hub of the propeller.
  • the tongue member 'I is rigidly connected and is preferably made in one piece together with the shaft or root 8.
  • the root part 8 may by cylindrical and provided with an annular groove 25 for rigid connection with the propeller hub and providing for adjustment of the propeller pitch.
  • Tongue 'I has a cross sectional configuration resembling the letter H; the cross section of the tongue diminishes towards the end, i. e. towards the point of the propeller blade.
  • Tongue I is provided with a plurality of bores 9 for accommodating bolts 3.
  • the tongue is therefore connected with a large part of the shells forming the propeller blade the contour of which is indicated by means of the dotted line 22 and the centrifugal forces set up in the blade shells act on a comparatively large area and not on the root of the blade body only as is the case with conventional propeller blades.
  • tongue and shaft are made of two parts. of two hollow shells I0 and II which are held together by means of a plurality of bolts I2 and which are covered by the veneer I3.
  • 'I'he tongue which corresponds to tongue 'I in Figs. 1 and 2 is made of two halves I4 and I5. These halves have substantially U-shaped cross sectional configuration and are bordered at their outer edges
  • the tongue or stem halves are provided withA edge strips I6 and I1 respectively which are provided with bores for accommodating bolts, screws, rivets or the like for connecting the propeller shells I0 and II.
  • the propeller blade proper consists halves Il and I5 is made of'one piece with the root or shaft parts I8 and I9 which together form the rotund shaft.
  • Each shaft half is provided with a bore or opening 20 and 2
  • the tongue halves Il and l5 are supplementarily pressed together by the bolts I2 which extend through the bores 26 and 21.
  • the embodiment of the present invention shown in Figures 3 and 4 has the advantage over the embodiment illustrated in Figs. l and 2 that the tongue is more rigidly connected with the blade shells. It is possible to first individuallyH connect tongue half I4 with shell I0 and tongue half I5 with the shell II by means of screws, bolts, rivets or the like. 'I'hereafter the two halves of the propeller blade can be connected by means of bolts I2 and the shaft or root halves I8 and I9 by means of bolt 28 extending through the bores 2
  • a propeller blade comprising a blade proper split by a cut extending substantially along the trailing edge and the leading edge into two parts, a stem member having a root portion and a tapered tongue portion of H-shaped cross sectional configuration and having a web portion and extending from said root portion and into the interior of said blade proper and being so positioned that said web portion is substantially parallel to the blade surfaces, and connecting means extending through said parts and through said web portion and rigidly connecting said parts with said tongue portion and with one another,
  • a longitudinally split propeller blade comprising a blade proper split substantially longitudinally into two blade parts by a cut extending substantially along the edges ⁇ of the blade,
  • a stem member having a root portion anda tongue portion extending from said root portion and into the interior of said blade proper, said root portion projecting from said blade. proper and being so constructed as to form the root o! said blade, said stem member being longitudi- ⁇ nally split into two symmetric parts, said bladeV parts being individually rigidly connected with the tongue portions of said stem parts, and connecting means extending through the tongue portions of said stem parts and through said blade parts and being accessible from the outside of said blade parts and rigidly interconnecting said blade parts and said stern parts.
  • a longitudinally split propeller blade comprising a blade proper split substantially longitudinally into two blade parts by a cut extending substantially along the edges of the blade, a stem member having a root portion and a tongue portion extending from said root portion and into the interior of said blade proper, said root portion projecting from said blade proper and being so constructed as to form the root of said blade, said stem member being longitudinally split into two symmetric parts, said blade parts being individually rigidly connected with the tongue portions of said stem parts, connecting means extending through the tongue portions of said stem parts and through said blade parts and being accessible from the outside of said blade parts and rigidly interconnecting said blade parts and the tongue portions of said stem parts, and another connecting means extending through and rigidly interconnecting the root portions of said stem parts.
  • a propeller blade having a surface forming hollow part substantially longitudinally split to form two half shell portions, a stem'member having a tongue portion of H-shaped crosssectional configuration and including a web portion and a channel on either side thereof, said tongue portion extending into said hollow part and between said half shell portions with the web por-V tion positioned substantially parallel tothe blade surfaces, longitudinal bulges projectingninward from said half shell portions and ilttingftightly into the channels of said tongue portion, fastening means extending through saidbulges and through said web portion and rigidly fastening said half shell portions to said stem member and to one another.

Description

Oct. 14, 1941. c. DoRNn-:R
PROPELLER BLADE Filed March 51, 193s lllalyem- I "alizee/l y lNVENTOR CLA U05 oE/v/E/e.
. ATTORNEY Patented Oct. 14, 1941 PROPEILLEBI BLADE Claude Dornier, Friedrichshafen-on-the-Bodensee, Germany, assigner oi' one-half to Dornier- `Werke G. m. b. H., Friedrichshafen-on-the- Bodensee, Germany Application March 31, 1938, Serial No. 199,165 In Germany April Z, 1937 4 Claims.
'I'he present invention relates to propellers, particularly for aircraft and more specifically to propeller blades which are made up of a plurality of parts which parts may be made of different materials.
The present invention is particularly useful in connection with variable pitch propellers the blades of which are made of wood.
It is an object of the present invention to provide a propeller blade which is' formed by two hollow shells which are held together by screws or other suitable connecting means and the surface of which may be veneered. The blade according to the present `invention comprises a metal shaft from which a tongue extends into the blade for about one third to two thirds of its length. Tongue and shaft may be longitudinally split into two parts which are held together by suitable connecting means.
Further and other objects of the present invention will be hereinafter set forth in the accompanying specification and shown in the drawing which, by way of illustration, show what I now consider to be a preferned embodiment of my invention. v
In the drawing:
Figure 1 is a cross sectional view of a propeller blade according to the present invention.
Figure 2 is an isometric illustration of the core or tongue member according to the present invention.
Figure 3 is a cross sectional view of a modified propeller blade construction according to the present invention.
Figure 4 is an isometric illustration of the split tongue which is used in connection with the construction shown in Figure 3.
Like parts are designated by like numerals in all figures of the drawing.
Referring more particularly to Fig. 1 of the drawing, numerals I and 2 designate the hollow shells which in conventional manner, form the propeller blade proper and may be made of wood, Bakelite or a similar light material. The shells are made of wood and are covered by means of a veneer 4. The interiors of the shells I and 2 are provided with reinforcements 5 and 6 respectively through which bolts 3 extend which hold the shells I and 2 together. The reinforcements may be in the form of longitudinal projections or in the form of a plurality of individuah boss-like projections. In the interior of the hollow blade a tongue like' member I which is preferably made of metal is provided. l
The body which comprises the tongue mem- (Cl. T10-159) ber 1 is illustrated in Fig. 2. It consists of shaft 8 which is rotund, forged, pressed or cast and which is provided with a reset 25 for mounting the shaft 8 to the hub of the propeller. To the shaft 8 the tongue member 'I is rigidly connected and is preferably made in one piece together with the shaft or root 8. The root part 8 may by cylindrical and provided with an annular groove 25 for rigid connection with the propeller hub and providing for adjustment of the propeller pitch. Tongue 'I has a cross sectional configuration resembling the letter H; the cross section of the tongue diminishes towards the end, i. e. towards the point of the propeller blade. Tongue I is provided with a plurality of bores 9 for accommodating bolts 3. The tongue is therefore connected with a large part of the shells forming the propeller blade the contour of which is indicated by means of the dotted line 22 and the centrifugal forces set up in the blade shells act on a comparatively large area and not on the root of the blade body only as is the case with conventional propeller blades. Due to the peculiar configuration of the tongue or Ystem 1 the propeller blade can have a very slender configuration from the root to the point and the outer end of the blade can be made very slim as is desired for aerodynamical reasons. If the cross section of tongue I would not diminish towards the outer end such favorable formation of the propeller blade would not be possible. It must be noted that the tongue I does not extend into the extreme end of the blade at all.
In the modification o-f a blade construction according to the present invention and shown in Figs. 3 and 4 tongue and shaft are made of two parts. of two hollow shells I0 and II which are held together by means of a plurality of bolts I2 and which are covered by the veneer I3. 'I'he tongue which corresponds to tongue 'I in Figs. 1 and 2 is made of two halves I4 and I5. These halves have substantially U-shaped cross sectional configuration and are bordered at their outer edges The tongue or stem halves are provided withA edge strips I6 and I1 respectively which are provided with bores for accommodating bolts, screws, rivets or the like for connecting the propeller shells I0 and II. Each of the tongue The propeller blade proper consists halves Il and I5 is made of'one piece with the root or shaft parts I8 and I9 which together form the rotund shaft. Each shaft half is provided with a bore or opening 20 and 2| respectively through which a connecting bolt 28 may be extended. Bores 20 and 2| are widened out at their outer parts for accommodating the head and nut of the connecting bolt so that the rotund outer configuration is not interrupted by projecting parts of the bolt. The tongue halves Il and l5 are supplementarily pressed together by the bolts I2 which extend through the bores 26 and 21.
The embodiment of the present invention shown in Figures 3 and 4 has the advantage over the embodiment illustrated in Figs. l and 2 that the tongue is more rigidly connected with the blade shells. It is possible to first individuallyH connect tongue half I4 with shell I0 and tongue half I5 with the shell II by means of screws, bolts, rivets or the like. 'I'hereafter the two halves of the propeller blade can be connected by means of bolts I2 and the shaft or root halves I8 and I9 by means of bolt 28 extending through the bores 2|) and 2|.
While I believe. the above described embodiments of my invention to be preferred embodiments, I wish it to be understood that Ido not desire to be limited to the exact details of design and construction shown and described, for obvious -modiiications will occur to a person skilled in the art.
I claim:
l. A propeller blade comprising a blade proper split by a cut extending substantially along the trailing edge and the leading edge into two parts, a stem member having a root portion and a tapered tongue portion of H-shaped cross sectional configuration and having a web portion and extending from said root portion and into the interior of said blade proper and being so positioned that said web portion is substantially parallel to the blade surfaces, and connecting means extending through said parts and through said web portion and rigidly connecting said parts with said tongue portion and with one another,
"said root portion projecting from said blade proper and being so constructed as to form the root of said blade. l
2. A longitudinally split propeller blade comprising a blade proper split substantially longitudinally into two blade parts by a cut extending substantially along the edges `of the blade,
a stem member having a root portion anda tongue portion extending from said root portion and into the interior of said blade proper, said root portion projecting from said blade. proper and being so constructed as to form the root o! said blade, said stem member being longitudi-` nally split into two symmetric parts, said bladeV parts being individually rigidly connected with the tongue portions of said stem parts, and connecting means extending through the tongue portions of said stem parts and through said blade parts and being accessible from the outside of said blade parts and rigidly interconnecting said blade parts and said stern parts.
3. A longitudinally split propeller blade comprising a blade proper split substantially longitudinally into two blade parts by a cut extending substantially along the edges of the blade, a stem member having a root portion and a tongue portion extending from said root portion and into the interior of said blade proper, said root portion projecting from said blade proper and being so constructed as to form the root of said blade, said stem member being longitudinally split into two symmetric parts, said blade parts being individually rigidly connected with the tongue portions of said stem parts, connecting means extending through the tongue portions of said stem parts and through said blade parts and being accessible from the outside of said blade parts and rigidly interconnecting said blade parts and the tongue portions of said stem parts, and another connecting means extending through and rigidly interconnecting the root portions of said stem parts.
4. A propeller blade having a surface forming hollow part substantially longitudinally split to form two half shell portions, a stem'member having a tongue portion of H-shaped crosssectional configuration and including a web portion and a channel on either side thereof, said tongue portion extending into said hollow part and between said half shell portions with the web por-V tion positioned substantially parallel tothe blade surfaces, longitudinal bulges projectingninward from said half shell portions and ilttingftightly into the channels of said tongue portion, fastening means extending through saidbulges and through said web portion and rigidly fastening said half shell portions to said stem member and to one another. l
CLAUDE DORNIER.
US199165A 1937-04-03 1938-03-31 Propeller blade Expired - Lifetime US2259247A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1937D0074995 DE698674C (en) 1937-04-03 1937-04-03 Single blades for controllable pitch propellers made of two wooden blade halves

Publications (1)

Publication Number Publication Date
US2259247A true US2259247A (en) 1941-10-14

Family

ID=7061830

Family Applications (1)

Application Number Title Priority Date Filing Date
US199165A Expired - Lifetime US2259247A (en) 1937-04-03 1938-03-31 Propeller blade

Country Status (3)

Country Link
US (1) US2259247A (en)
DE (1) DE698674C (en)
GB (1) GB513258A (en)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2454200A (en) * 1944-10-16 1948-11-16 Singer Mfg Co Molded impeller
US2477113A (en) * 1942-02-19 1949-07-26 Autogiro Co Of America Rotor blade for rotative winged aircraft
US2561705A (en) * 1942-08-08 1951-07-24 Emil R Lochman Propeller and method of propeller manufacture
US2652121A (en) * 1950-06-06 1953-09-15 United Aircraft Corp Hollow propeller blade with bulbed core
US2659444A (en) * 1949-06-21 1953-11-17 Autogiro Co Of America Molded aircraft sustaining rotor blade
US2918977A (en) * 1956-06-25 1959-12-29 Koppers Co Inc Blade assembly
US2990018A (en) * 1959-11-13 1961-06-27 Moore Co Fan
US3085631A (en) * 1958-05-29 1963-04-16 Svenska Flaektfabriken Ab Propeller fan blades
EP2243953A2 (en) * 2008-11-14 2010-10-27 General Electric Company Turbine blade fabrication
US20110081247A1 (en) * 2009-10-01 2011-04-07 Vestas Wind Systems A/S Wind Turbine Blade
US20110091326A1 (en) * 2008-05-07 2011-04-21 Vestas Wind Systems A/S Sectional Blade
US20110158788A1 (en) * 2008-08-31 2011-06-30 Vestas Wind Systems A/S A sectional blade
US20130129507A1 (en) * 2011-11-23 2013-05-23 The Boeing Company Composite Propeller Spar
US20130280084A1 (en) * 2012-04-18 2013-10-24 Hamilton Sundstrand Corporation Propeller blade with internal stiffener
US20140286780A1 (en) * 2011-08-05 2014-09-25 Tecsis Tecnologia E Sistemas Avancados S.A. Aerogenerator blade tip segment and method of assembly
US9388789B2 (en) 2009-12-02 2016-07-12 Vestas Wind Systems A/S Sectional wind turbine blade
CN106945846A (en) * 2017-03-01 2017-07-14 中国航天空气动力技术研究院 A kind of low reynolds number air propeller profile determines method
CN112943652A (en) * 2015-12-14 2021-06-11 亨特风扇公司 Ceiling fan
US11674526B2 (en) 2016-01-22 2023-06-13 Hunter Fan Company Ceiling fan having a dual redundant motor mounting assembly

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE969542C (en) * 1944-04-20 1958-07-03 Hans Pferdmenges Device for the production of a draftable sliver from endless synthetic fibers
FR2942512B1 (en) * 2009-02-20 2011-05-27 Airbus France DAWN FOR TURBOMACHINE RECEIVER, COMPRISING ONE FOOT SCINED IN TWO PORTIONS MOUNTED ON ONE ANOTHER.
FR2942513B1 (en) * 2009-02-20 2011-05-27 Airbus France DAWN FOR TURBOMACHINE RECEIVER, COMPRISING A BLADE PART INCORPORATING A MECHANICAL FUSE

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2477113A (en) * 1942-02-19 1949-07-26 Autogiro Co Of America Rotor blade for rotative winged aircraft
US2561705A (en) * 1942-08-08 1951-07-24 Emil R Lochman Propeller and method of propeller manufacture
US2454200A (en) * 1944-10-16 1948-11-16 Singer Mfg Co Molded impeller
US2659444A (en) * 1949-06-21 1953-11-17 Autogiro Co Of America Molded aircraft sustaining rotor blade
US2652121A (en) * 1950-06-06 1953-09-15 United Aircraft Corp Hollow propeller blade with bulbed core
US2918977A (en) * 1956-06-25 1959-12-29 Koppers Co Inc Blade assembly
US3085631A (en) * 1958-05-29 1963-04-16 Svenska Flaektfabriken Ab Propeller fan blades
US2990018A (en) * 1959-11-13 1961-06-27 Moore Co Fan
US9765756B2 (en) 2008-05-07 2017-09-19 Vestas Wind Systems A/S Sectional blade
US20110091326A1 (en) * 2008-05-07 2011-04-21 Vestas Wind Systems A/S Sectional Blade
US20110158788A1 (en) * 2008-08-31 2011-06-30 Vestas Wind Systems A/S A sectional blade
EP2243953A3 (en) * 2008-11-14 2017-03-29 General Electric Company Turbine blade fabrication
EP2243953A2 (en) * 2008-11-14 2010-10-27 General Electric Company Turbine blade fabrication
US8177514B2 (en) * 2009-10-01 2012-05-15 Vestas Wind Systems A/S Wind turbine blade
US20110081247A1 (en) * 2009-10-01 2011-04-07 Vestas Wind Systems A/S Wind Turbine Blade
US9388789B2 (en) 2009-12-02 2016-07-12 Vestas Wind Systems A/S Sectional wind turbine blade
US20140286780A1 (en) * 2011-08-05 2014-09-25 Tecsis Tecnologia E Sistemas Avancados S.A. Aerogenerator blade tip segment and method of assembly
US20130129507A1 (en) * 2011-11-23 2013-05-23 The Boeing Company Composite Propeller Spar
US9168998B2 (en) * 2011-11-23 2015-10-27 The Boeing Company Composite propeller spar
US20130280084A1 (en) * 2012-04-18 2013-10-24 Hamilton Sundstrand Corporation Propeller blade with internal stiffener
US9168999B2 (en) * 2012-04-18 2015-10-27 Hamilton Sundstrand Corporation Propeller blade with internal stiffener
CN112943652A (en) * 2015-12-14 2021-06-11 亨特风扇公司 Ceiling fan
US11525462B2 (en) 2015-12-14 2022-12-13 Hunter Fan Compnay Ceiling fan
CN112943652B (en) * 2015-12-14 2023-02-03 亨特风扇公司 Ceiling fan
US11592035B2 (en) 2015-12-14 2023-02-28 Hunter Fan Company Ceiling fan bearing system
US11644048B2 (en) 2015-12-14 2023-05-09 Hunter Fan Company Ceiling fan
US11668327B2 (en) 2015-12-14 2023-06-06 Hunter Fan Company Ceiling fan
US11674526B2 (en) 2016-01-22 2023-06-13 Hunter Fan Company Ceiling fan having a dual redundant motor mounting assembly
CN106945846A (en) * 2017-03-01 2017-07-14 中国航天空气动力技术研究院 A kind of low reynolds number air propeller profile determines method
CN106945846B (en) * 2017-03-01 2019-02-19 中国航天空气动力技术研究院 A kind of low reynolds number air propeller shape determines method

Also Published As

Publication number Publication date
GB513258A (en) 1939-10-09
DE698674C (en) 1940-11-15

Similar Documents

Publication Publication Date Title
US2259247A (en) Propeller blade
US2312219A (en) Aircraft propeller
US2659444A (en) Molded aircraft sustaining rotor blade
US2116055A (en) Propeller
US2304322A (en) Hockey stick
US1785543A (en) Metal propeller
US1937966A (en) Propeller for aircraft
US2086307A (en) Screw propeller and the like
US3461966A (en) Unitary fixed pitch aircraft propeller
US2389760A (en) Airscrew
US2248221A (en) Propeller blade
US1835913A (en) Propeller
US1817556A (en) Propeller for aircraft
US1988202A (en) Hollow propeller
US2149951A (en) Propeller
US2882974A (en) Propeller blade
US1380431A (en) Propeller
GB439249A (en) Improvements relating to screw propellers
US2116054A (en) Propeller
US2477113A (en) Rotor blade for rotative winged aircraft
US1826026A (en) Propeller
US1638695A (en) Screw propeller
US1804434A (en) Aeronautical propeller and method of making the same
US1399290A (en) Propeller for aircraft
US2014242A (en) Propeller