US1402539A - Aeroplane propeller or the like - Google Patents

Description

0. A. ROSS. AEROPLANE PROPELLER 0R THE LIKE. APPLICATION FILED sEPT.1'4,1917.

1,40225 39, Patented Jan. 3, 1922o UNITED STATES r-ATENT OFFICE..

OSCAR A. ness, or New YORK, `1v. y.

PROPELLER THE LIKE.

To @ZZ/whom it may concern.'

Belt known thaty I, OsoAn A. Ross, a citizen of the United States of America, re.-

siding at 115 Carnegie Hall, New Yorkcity,

county of New York, State of New York, have invented a new and useful Improvement in Aeroplane Propellers or the like, yof which the following is a specification.

Thispinvention upon which is based my present application for Letters Patent pertains to air pro'pellers, or screws for aeroplanes. They are employed preferably in connection with that class of aeroplanes known as the tractor type. My invention has for its more prominent objects the attainment in a more economical and effective manner of the results, or yoperations hereinafter specified.

Primarily the purpose in view is to permit propellers to be operated at a much higher rotative speed than those now in common use. At the present time the limit of rotative speed of propellers is such that gearing is interposed between ythe motor'and propeller to V`permit obtaining maximum etliciency from the motor, the' motor running considerably faster than the propeller. lt

is evident that this 'gearing entails a loss of power, adds weight and is otherwise objectionable.

A further object is to furnish a shield formed with a streamline surface for the center portion of the propeller, such, that the air at the center of the propeller will be forced out into the maximum torque producing portion of the blades thereby forming a dense, compact column of air for the efficient portion of the blades to work in. It is a well known fact that with an 8 to 9 foot diameter propeller in excess of 90 per cent of the torque is obtained in the last 18 to 24 inches of the blade.

All the above and other objects sought are attained by the propeller, which for purposes of specific illustration, is shown in the accompanying drawings, in which- Figure 1, is a plan View of my improved propeller looking at lthe forward end of an aeroplane.

Figure 2,1is a side velevation of Figure 1.

Figure 3, is a modification of means to reenforce the propeller blade shown in Figures 1, and 2.

Figure 4, is a diagrammatic illustration of stresses in my improved form of propeller in action.

ySpseither-ition of Letters lvatent. y Patnted Jan, 3 1922,` Application filed September 14, 1917. Serial 1No. 191,438'. i i

propeller, are, or need be, of any special' or unusual construction, but for amore .ready understanding Vof the devicek and of its operation, a preliminary description of the construction maybe apposite. V

Referring to Figures 1, and 2,r 1 1, are

the propelling portionsy of theV propeller blade 2. The circular sectors 3 3, may `be integral or secured to the blade in any approved manner, as for example, gluing land dowelling. The hub 4, with flange 5,:and bolts 6,3form the unit for securing the propeller to the motor of the aeroplane.V

The shield formedwith a streamline surface 7, of cone like construction is secured in place by screws 8, and is notched on oppositesides to receive the blade 2. Reinforcing, or bracing members 10, are preferably fitted, glued and dowelled tothe center section 2, screws 12, assisting in securing said members to the said center section'.y Cross f members 9,V serve to prevent members `10,.

from"`bu'lckling, yor springing as lstrains, 'are placed upon them by springing, or bending of the propeller ends 1 1, as will more fully be hereinafter described. Screws 11, are

shown as the preferable means for securing to Figure 5, the solid line S, represents the mean radial axis of a propeller of ordinary design, rotating on axis A. The distance H,

`represents the nominal hub `diameter of the propeller and, therefore, assuming that the machine to which the propeller is attached is traveling in the direction of arrow W, the deflection of the propeller blades will be substantially in accordance with dotted line D. The dotted line T and arrows 16, represents the circumferential plane in which the maximum torque is produced by Athe propeller. It is evident therefore, that CIA sents the characteristics of the inventors propeller, it is noted that the leverage F, is relatively small as compared with E, of Figure 5, therefore the bending moment at Y, is much reduced for a similar rotative speed of compared propellers and obviously permits of a much higher speed with the applicants propeller. The hub vdiameter in applicants propeller is practically represented by the distance G, the center section 2, with reinforcing members 9, and l0, forming a rigid unyielding structure.

As stated hereinbefore, practically all the torque developed by an aeroplane propeller is obtained from the outer one half ofthe blades.V Owing to a factor known generally as the slip, said slip being due to head resistance, etc., a propeller never travels progressively at the theoretical speed calculated from its pitch. For this reason theair is always tending to be drawn into the blades. This causes a partial vacuum in front of the propeller again tending to develop churning, of the air thereby reducing the eiiiciency and resulting torque. In

my improvedv propeller, thevshield formed with a streamline surface 7, forces the oncoming air in the direction of arrows l5, to the outer half of the blade thereby forming a dense, compact column of air for the eiicient part of the blades to work on.

From all investigations conducted by the vinventor vit appears that the best ratio of shield formed with a streamline surface and propeller diameters are substantially as l, is to 2. Thatis the shield at its greatest diameter should be substantiallyy one half the diameter of the. propeller.

Although I Ahave herein shown and described only certain forms of my invention, it is understood various changes and modications may be made therein without departing from the spirit of the invention.

What I claim is 1. In combination with an aeroplane propeller, a shield formed with a streamline surface attached theretoV and means for reinforcing said propeller, said means being contained within the peripheral surface of said shield substantially as described. Y

2. In an aeroplane driving means, in combination: a propeller; a shieldformed with a* streamline surface located forwardly of the propeller; meansto support the shield,

and reenforcingmeans for the propeller 4located rearwardly of the shield.

In testimony whereof, Oscar A. Ross, has signed his name to this specification in the presence of two subscribing Witnesses, this 18th day of August, 1917.

OSCAR A. ROSS.

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