US1461866A - Air propellef - Google Patents

Description

July 17, 1923; 1,461,866

C. DORNIER AIR PROPELLER Filed. June 28 1920 Jim Fla

INvENmR:

meme July 17,1923.

-. STATES cnaunn noamna, or rnmnmcnsnarmr, GERMANY, assrenoa, w mm: assrenmums, 'ro DOBNIEB-METALLBAUTEN- GESELLSCHAFT MIT BESCHB'A'NK'I'ER- m- PATENT OFFICE.

' TUNG AND CLAUDIUS DORINIER, OR FBIEDRICHSHAFEN, A. 3., GERMANY.

Am raornnrinr.

Application filed June 28, 1920. Serial 'No. 892,559. I (GRANTED UNDER. THE PROVISIONS OF THE A01 OF MARCH 3, 1921, 41 STAT. I.., 1318.)

To all whom it may concern:

' Be it known that I, CLAUDE DonNmn, a citizen of the GermanEmpire, residing at F riedrichshafen, Germany, have invented 5 certain new and useful Improvements in Air Propellers (for which I have filed an application in Germany Sept. 2, 1916), of which the following is a specification.

My invention refers to airropellers with hollow blades. Such propel ers can be obtained by flattening by pressure a hollow tubular body at its ends after the manner of propeller blades and by developing the center as the boss of the screw. The subsequent transformation of a. tubular body into a two bladed screw, however, can only be achieved with difiiculty' with the desired-accuracy. On the other hand propellers are known in which the hollow blades are mounted on blade-supports fixed to the boss of the screw. In this latter type of construct on, however,

danger of the blades being hurled off by the centrifugal force. It' is the object of to avoid the drawbacks of both types of construction. This aim isachie'ved by the propeller being composed of several interior andexterior parts stretchin at least approximately from one blade e ge to the other and by the blade laminations as well as the arms being-utilized as supporting parts.

Accordingly the object of the invention consists in an air-propeller with hollow blades in which two blade laminations stretching continuously from one blade edge to the other, and several pairs of stays or rolled section girders also stretching from end to end, are employed. Accordin to-the invention the section girders situate on the outside, at the same time, serve as transition bodies 'for the transition from one blade lamination to theother; In this manner great strength of the finished propeller can be achieved .with easy manufacturing and great accuracy of the va ious parts. The manufacture: of an air-propeller be"- comes particularly advantageous, if the.

parts of the blades situated outside the inner pair of stays are made lighter than the parts. inside .ithe pair of stays. As the middle part of the propeller which is stayed there exists the my present invention by D the girders, possesses great strength owing to its box 'gi rders shape, the blade ends which are not fastened together yet, can be bent up elastically a little without difliculty, thereby rendering the inner, stays easily accessible for riveting tools, etc. Besides, the blade becomes lighter.

The drawing attached to this specification and forming part thereof, illustrates an ex ample of a modification of the present invention in a purely diagrammatical manner.

' sists of the boss of the screw, a suction and a pressure blade lamination continuous in both cases, the inner'stays, the outer stays 'and two boom butt straps.

Manufacture can take place in the following manner: First the bosses of the screws are riveted to ether with the two inner stays and each lade with the pertinent boom butt strap. Thereupon the one to the boss of blade lamination is riveted the screw as well as the flanges of the cont nuous inner stays. Then the second blade is riveted on. whilst holdin up takes place from the sides or the en s. Finally the outer stays ,are riveted in. For these the rivets are riveted right through, whilst for the inner stays the rivets'only connect one blade lamination to the supporting stay flan e at a time,

ostly the pressure side will be plane or only slightly vaulted. The pressure blade lamination can therefore be bent up during the riveting beginning from the boss of the screw, thus enabling specially easy holding- 'up. It is useful to make the blade laminations and stays of light metal, whilst steel ispreferable for the boss of the screw. The thickness of the blades can decrease from the boss of the-screw towards the points. It is advisable to give the inner staysa U- shaped cross-section with the flanges pointing outwards. In the case of very large p can be employed.

. dimensions compound sections or box beam sections may also be employed. -Th e rivet heads on the outer surface must be countersunk., The boom butt straps can also be left 6 out. A special. advantage of this construction lies in the fact that small screw bosses I claim 1 In a hollow propeller in eombinatiom. l0 two metal plates suitabl K edges and extending eac from the outer united at their end of one blade to the outer end of the other, and a plurality of channels inserted between and fixed to said blades and extending longitudinally thereof one end 5 to the other.

inglongitudinally thereof from one'end to the other, the middle portions of said plates being thicker than the portions adjoining :6 their longitudinal edges. v

In testimony whereof I aflix my signature.

CLAUDE DORNIER.

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