US1831394A - Aeronautical propeller - Google Patents

Description

Nov. 10, 1931. s. A. REED AERONAUTICAL PROPELLER Filed 001;. 29, 1929 Eta R O N w W SLANUSA REED. 1

Patented Nov/1 0, 1931 UNITED STATES PATENT; orrlca SYLVAN'US A. REED, 01 W YORK, N. Y., ASSIGNOR TO THE REED PROPELLER GOM- IPANY, INC., A CORPORATION OF NEW YORK .AERONAUTICAL PROPELLER Application filed October 29, 1929. Serial No. 403,164.

My invention relatesto aeronautical pro pellers and is an improvement on those types of propellers described in my U. S. patents numbered respectively 1,463,556, 1,518,410, and 1,542,412. More'particularly the invention has reference to a composite propeller, preferably of a heavy metal having, throughout its inner portion, a light metal reinforcing or strength giving core or hub. The term inner portion is used to designate the pro peller part substantially within one-half the blade length, Whereas the term outer portion is used to designate the remaining outer part thereof.-

The principal stresses experienced by a propeller are centrifugal, which centrifugal stresses I will call C; bending, due to thrust and the torque of the engine, which bend ng stresses I will call B; and torsional, tending to change the blade angles, WhlCh torsional stresses I will call T. 1

In my improved type composltepropeller,

I prefer to make the dimensions of the pro- I peller itself inherently adequate to sustain unaided all of the stresses C, as well as all of the stresses B and T which affect the outer portions, but inherently inadequate to sustain unaided, the stresses B and T 1n the 1nner portions. Moreover, I prefer to make the propeller in a single iece from tip to tip with thin sharp outer lade portions and of rolled forged steel.

The reinforcing part of the composite propeller consists of a hub or core member with blade extensions overlapping the inner portions of the propeller proper and of dimensions inherently adequate to sustain its own stresses C and also to sustain the stresses B and T of the propeller blades as well as of itself. Preferably such hub or core portion is made in 'onepiecehalves of a strong forged light alloy such as duralumin, and the blade extensions are fastened to the propeller blades by bolts or rivets passing thru elongated holes or slots extending lengthwise the propeller axis.

Referring to the drawings,.where'in like reference characters denote like or corresponding parts.

Fig. l is a side or edge view of the propeller;

Fig. 2 is a plan view; Fig. 3 is a plan View of the blank or slab from which the propeller proper is shaped;

Fig. 4 is a multiple cross-section showing the construction ofthe propeller at different points throughout its length, and

Fig. 5 is a side or edge view of one of the halves of the hub or core.

7 In Figs. 1 and 2, the thin solid steel blades of the propeller are designated as 1 and 2, Whereas 3 and 3m designate twin hubs each having integral blade extensions 4, 4a, 5 and 5a. The parts 3, 4, and 5 on the one hand and the parts 3a,4a, and 5a, on'the other, are each preferably made integral and of forged duralumin. 6 and 6a are shaft holes splined or keyed to secure the propeller to an aircraftmotor shaft extension. 7, 7, 7, 7 are bolts for fastening the hub blades or extensions to the propeller blades 1 and 2.

The one plece steel slab from which the blades 1 and 2 are formed is best illustrated in Fig. 3. Throughout its center portion, and

hence throughout the inner portions of the blade, said slab is excavated as at 8 to very appreciably reduce the mass of material. At

the ends of the excavation or orifice 8 channels 9 are provided. These channels, which are rovided on opposite faces of the slab, admit of the close fitting engagement of the hub flanges to the end that the composite inner blade ends may have a single and efiicient aerofoil section. Also, as will be noted, the 5 steel slab, throughout its central region, has maximum peripheral dimension consistent with the retention of adequate cross-sectional area to sustain the centrifugal stresses.

The sections of Fig. 4, reading from left so to right, show the construction of the propeller at the various points indicated by the I dotted lines aa, 6-4), 0-0, and dd, res'pectively of Fig. 2. The holes for the bolts 7 7, 7, 7, are slotted in the direction of the blade axis in orderto prevent the hub flange extensions 4, 4a, 5, and 511 from sustaining any of the centrifugal stresses of the blades. In shaping the flange extensions care should be exercised to provide, in thefinished prodloll so their inner portions. Also, in my not, a composite ropeller of favorable blade and means for fastening said flange extenrofile at all statlons or oints throughout its sions to the propeller blades. ength. By relieving t e propeller proper from the burden of sustainingits own stresses excavated, and hence materially li htened B and TI am able to dispense with considerblades formed from a single length strong able mass in the innerportion of the blades forged relatively. heavy metal continuous and thus may very materially reduce the from tip totip with the outer portions thereover-all weight.

With a com osite construction such as cross-sections inherently adequateto resist herein suggeste it is only necessar to reboth rupture and deformation, said blades tain in the inner part of the prope er sufinthe vicinity of said excavations having sufficient cross-section at al l .,.radii to sustain ficient cross-sectional area to sustain unaided the stresses C with" aproper safety factor. the centrifu al stresses tho insuflicient to sus-' The hub. and flange extensions require, in min unaide the angle changing stresses; a order to meet the stresses B and T, ample hub and core of strong tho relatively light over-all area rather than ample section, thereweight metal for reinforcing said excavated fore the extensions, if desired, may be holbla eportion,said hub and core being formed lowed out in any convenient manner to rewith integral radial elongated flange extenduce weight. A propeller thus characterized sions havmg inherently adequate torsional so has practically all the merits of .a single rigidity to g ve said excavated blade portion piece solid metal propeller with robably a the necessary factor of safety against angle considerable saving in cost and without machan ing stresses;. and means for fastening teriall exceeding the wei ht of a similar saidd prope er of strong light alIoy. H 3. In an aeronautical propel er, centrally In my U. S. Patent #1,463,556 I proexcavated, and hence materially li htened d hub blocks of light metal which assist blades formed from a single length 0 strong in maintaining the central bends of the pro forged relatively heavy metal continuous peller, but such hub or hub blocks have no fromtip to tip with the outer portions thereof extensions to support the blades througyhout thin and sharp and having at all radii cross S. sections inherently adequate to resist both Patents 1,518,410 and 1,542,412, while I 'derupture and deformation, said blades in the scribed ahub with flan estwistedto tonform vicinity of said excavations having sufficient to the blades and atta ed thereto for transcross-sectional area to sustain unaided the mission of thrust and engine power, such hub centrifugal stresses the insufficient to sustain 85 flan do not assist in-retaming the blade unaided the. angle chan ing stresses; a hub ang e of the propeller against torsional and core of strong tho re atively light weight stresses. i 'metal for reinforcing said excavated blade While I have described my invention in portion, said hub and corebein detail in its present preferred embodiment, it with integral radial elongated ange ex- I will be obvlous to those skilled. in the art, tensions having inherently adequate torafter understanding m invention, that varisional ri 'idity to give said excavated blade ous changes and modi cations may be made portion t e necessary factor ofsafety against therein without departingl from the s irit or angle changing stresses;. and-means passing scope thereof I aim int e appends claims thru holes slotted in a radial direction for .5 to cover all such modifications and changes.

What I claim is: peller blades.

1. In an aeronautical propeller, blades 4:. In. a composite aeronautical propeller, formed from a single piece of stron forged blades formed from a single length of strong relatively heavy metal continuous om tip fprged relatively heavy metal continuous to tip with the outer portions thereof thin from tip to tip with the outer portions therefastening said flange extensions to the .pro-

and sharp and having at all radii cross-secof thin and sharp and having at all radii.

tions inherently adequate to resist both ru cross-sections inherently adequate to resist .ture and deformation, said blades, in t 0 both rupture and deformation, and with the vicinity of the centerv of rotation of the proiimer portions thereof excavated to obtain a *peller, having sufiicient cross-sectional area maximum of wei ht reduction consistent with to sustain unaided .the centrifugal stresses retaining in sai inner blade portions suftho insuficient to sustain unaided angle ficient cross-sectional area to sustain unaided changing stresses a hub and core of strong the centrifugal stresses incurred during use, tho relatively light weight metal for reintho insufficient in cross-sectional area to susforcing said-inner blade portion, said hub and tain unaided the torsional and bending core being formed with integral radial elonstresses imposed on the blades; a hub and core gated flange extensions having inherently of strong tho relatively-1i t weight metal adequate torsional rigidity to give to said for reinforcing said innerb ade portions, said inner portions of the blade the necessary fachub and core being formed with integral tor of safety against angle changing stresses; radial elongated flange extensions having in- 2. In an aeronautical propeller, centrally of thin and sharp and having at all radii ange extensions to the pro eller blades.

formed j herently' adequate torsional rigidity to give aerofoil profile throughout a substantial porto said inner blade portions the necessary tion of said reinforcement.

factor of safety against angle changing stresses, and meansattaching the ropeller blades to said hub and core mem er, said 'means being carried thru holes slotted in a radial direction and disposed to relieve the attaching means from centrifugal stresses.

5. In an aeronautical propeller, blades formed from a single excavated metal piece continuous from tip to tip and shaped at all radii throughout the outer portions of the respective blade lengths to favorable blade profiles, and a radially elongated hub and core portion substantially co-extensive with said excavated blade portion and to which the blades are fastened for reinforcement against angle changing stresses.

6. In an aeronautical propeller, blades formed from a single excavated metal piece continuous from tip to tip and shaped at all radii throughout the outer portions of the respective blade lengths to favorable blade profiles, and a radially elongated hub and core portion substantially co-extensive with said excavated blade portion and to which and with which the inner blade portions are fastened and shaped to favorable blade profiles respectiVelyI 7. In an aeronautical propeller, blades of a relatively heavy metal excavated throughout a substantial portion of their respective lengths and to an extent necessitating the employment of a reinforcing means for adequately sustaining the angle changing stresses encountered in actual service, and a combined hub and core member of relatively light metal fastened to the respective blades and elongated radially to reinforce the excavated portions thereof, each said blade,

throughout the inner portion of its length, and in conjunction with said elongated core member, and throughout the outer portion of its length, independently of said elongated core member, being shaped to favorable blade profiles at all radii. 7

8." In a composite metal aeronautical propeller, a propeller blade including a metal piece contmuous from root to tip, said metal plece, in the vicinity of said blade root and for a substantial portion of the blade length,

being excavated to an extent necessitating the employment of a reinforcing means, not for the purpose of sustaining any substantial portion of the centrifugal stresses, but for the purpose of sustaining a substantial portion of the angle changing stresses en:

countered in actual use, and means associated .with said excavated blade portion and fastened to said blade and of a lighter material,

than said blade, said means providing the necessary reinforcement where remforce-' ment is required and being faired with the continuous metal piece to approximately SYLVANUS A. REED.

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