Патент USA US2129206код для вставки
Sept» 5, 1933'- H. VELLINGHAUSEN ‘ 2,129,206 MEANS FOR MQUNTING PROPELLER BLADES ' .Filed Nov. 21, 1936 ~ 2 7n veni‘or 3/- iy/mz/zgmsen Patented Sept. 6, 1938 2,129,206 UNITED ‘STATES PATENT OFFICE 2,129,206 MEANS FOR MOUNTING PROPELLER BLADES Hermann" Ellinghausen, Bremen, Germany Application November 21, 1936, Serial No. 112,154 ‘In Germany November 23, 1935 5 Claims. (Cl. 170-459) The present invention relates to ‘propellers and longitudinal section of a blade, Fig. 2 the blade more particularly to means, for fastening the socket with the stlmip of the blade in a cross blades of wood propellers to the hub socket. section and Fig. 3 a portion of an anchor in ele For some purposes wooden propellers are pre vation. Referring to the drawing, the fastening 5 ferred to the metallicones. The increase of speed arrangement comprises a plurality of round steel 5 resulting from the steady development of the aeroplanes and which is not yet definitive, on account of the large difference of the starting and service speeds almost generally requires pro ” pellers with variable pitch or adjustable blades, and thus a propeller having adjustable wooden blades is of paramount importance in the con struction of aeroplanes. When however the two blades of a wooden ‘pro 15 peller are, ‘separated from one another with a rods or anchors a uniformly distributed over the cross ‘section of the blade'stump, secured by nuts 0 in the socket bottom and having a diameter which is towards the free end reduced in a step by-step manner, these rods having the highest possible tensile strength and carrying a plurality of round steel washers b properly spaced and prevented from being stripped off the red by the latter being provided with collars obtained 15 by upsetting in a red-hot condition. As these view to their adjustability the advantage afforded - collars are made by upsetting, all fibres of the a by the high tensile strength of wood in the direc tion of its ?bres will be lost at the hub. ‘On the other hand it has not yet been possible to fasten 20 the wooden blades in the metallic sockets, by means of which the blades are revolubly con nected to the hub in the same way as metallic blades, in such a manner that this connection is able to safely and durably stand the centrifugal and vibration forces to which such wooden blades are subjected. - steel of the rods remain uninjured and transi tions of suilicient radii are formed between the collar and the rod proper so that in all cross 20 1 sections the said rods are not injured and may be fully stressed with the particular permissible stress. As compared with the systems already known this arrangement not only results in a reduction of weight but also prevents both the cross section of the blade stump and the glued 25 joints of the wood lamellas from being materially Various systems have already been known weakened. . which are based on the prospective idea that The washers I; inserted with the steel rods be the centrifugal forces acting in the blade‘ be . tween at least two layers of the wooden blade will 30 taken up at as many points as possible; however subject an imagined wood cylinder to shear, the 80 the manner in which these forces are to be taken diameter of which corresponds to that of the par up by no means corresponds to the magnitude of the forces developed nor to the conditions of service so that no practical success was secured in this way. ‘ The present invention relates to means for fas tening wooden blades in the sockets of air pro pellers and more particularly adjustable pro pellers, and the object ‘of the invention is to 40 provide for means by which the centrifugal and vibration forces are'taken up in the wooden blades and transmittedgtherefrom to the blade sockets thereof in a very safe way. This eifect is ob-_ tained by, the fact that the tensile strength of "' the fibres as lost by the separation of the two blades is replaced by one or several areas re sisting to shearing forces in the‘ wood of the blades and the size of which corresponds to the ‘ stress undergone, and that~ according to the in 50 ventionrsuch an arrangement is provided for that a uniform stress in the shearing area or areas is ensured without the tensile‘ and bend ing strength of the woodenblade being thereby 55 adversely affected, , In the accompanying drawing Fig. 1 shows a ticular washer and the length of which corre sponds to the distance of two adjacent washers. According to loading tests accomplished, the re sistance to shear of.such a cylinder surface is 85 so high that as a rule 7 to 8 washers will be suf ?cient. K . . As hereinabove described the rods 0 are at tached to the socket by means of the nuts 0. The socket ‘comprises an outer cup-shaped mem 40 ber 0 having an annular ?ange h by means of which the blade may be bolted to the propeller hub. An inner cup-shaped member I in the nature of a lining may-be provided within the member e but such an inner member. is not necessary and forms no part of the present in vention. ' , ' The steel rods are inserted between the layers of the wooden blade with a definite play so that, ' when themgts are tightened in order that the 50 anchors comprising the rods and washers are put under tension, these rods are allowed to freely move-"in their grooves and to integrally transmit the stress to the washers. A new effect acting in the same direction, of the anchors will result 2 ’ 2,129,296 ‘from the loose seating of the washers on the rods and from the rounded shape of the collars (shown at d) obtained by upsetting. Asxit is rather dif ?cult practically to produce the hollow spaces for the washers exactly registering in two ad jacent layers of the blades, the mobility of the washers allowing an inclination of them on the anchors will cause a uniform distribution of the pressure over the two adjacent layers without the rod being stressed unilaterally, the rounded collars permitting of a corresponding attitude to ~ the washers. When at any point of the bedding of an an chor the distance of adjacent seatings in the wood of, the blade does not exactly equal the each tension member being arranged between two laminations, collars carried by said tension mem bers and a washer adiacent the hub socket side of each collar for engaging two laminations. 2. Supporting means for propeller blades ac cording to claim 1 characterized by the features that the washers are tiltablymounted on the . tension members. ' 3. Supporting means for propeller blades ac the blade. 4. Supporting ' _ means ‘ for propeller . blades formed of wood laminations which extend lon on account of the high shearing strength of the cracking of the wood will take place. In this gitudinally in the’ direction of the length of each blade comprising, a hub socket for receiving the inner end of the blade, metallictension mem bers extending into the wood blade, said tension members being uniformly distributed over the way again the pressure will be distributed more cross section of the blade and each tension mem against the pressure surface of the washers and > uniformly over all washers of the anchors. , ' The design and the bedding of these novel an 25 chors thus largely warrant that tightening the anchors after the blade stump having been in— troduced into" its socket, by uniformly tightening the glued joints. ber being arranged between two ‘laminations, said hub socket, integral collars on said tension members at spaced points along. the length there being uniformly distributed over the cross section of the blade and each rod being arranged be ' prising, a hub socket for receiving the inner end tween two laminations, means for fastening said rods to. said hub socket, arcuate shouldered col lars carried by said rods,»washers mounted on said rods adjacent each collar and between the collar and the hub sbcket, and said washers en of the blade, metallic tension members extend gaging two adjacent laminations whereby each I claim: 40 -_ 1. Supporting means for propeller blades formed of wood laminations which extend in the direction of the length of each blade com 45 ing into the wood blade and secured to said sock et, said tension .members being uniformly dis ll means for fastening said tension members to ‘ of, washers mounted on said tension members the‘nuts, will result not only in a uniform initial adjacent the hub socket side of each collar, and -' tension in the various blade and blade stump said washers engaging equal parts of two lami 80 cross sections but also in an initial tension which - nations. 5. Supporting means for propeller blades is uniformly distributed over the whole length of each anchor and thus also over a correspond formed of wood laminations which extend in ingly large portion of the wood of the blade. In the direction of the length of each blade com comparison with arrangements already ‘known prising, a hub socket for receiving the inner end 35 the novei fastening means further distinguishes of the blade, rods extending into the wood blade itself by the fact that the loose bedding of the and through the'rbase of said socket, said. rods ‘ washers, developes no forces tending to cleave 10 cording to claim l'characterized by the feature that the tension members are embedded with play in the adjacent‘faces of two laminations of spacing of the washers concerned the result will, cylindrical shearing surface, be a corresponding compression of the wood ?bre ends contacting 250 tributed over the cross section of the blade and washer may tilt» on said arcuate shoulders. . HERMANN EILINGHAUSEN. '