US2408677A

US2408677A - Propeller spinner

Info

Publication number: US2408677A
Application number: US499674A
Authority: US
Inventors: Owner Frank Morgan
Original assignee: Rotol Ltd
Current assignee: Rotol Ltd
Priority date: 1942-03-23
Filing date: 1943-08-23
Publication date: 1946-10-01
Anticipated expiration: 1963-10-01

Description

' o@ `1, 1946v f PROPELLER SPINNER l Filed Aug. n2s, 1943A 3 Sheets-Sheet-1 F. M; OWNER 2,408,677

Oct. 1, 1946'.

F. M. wNER 2,408,677

' PROPELLER SPINNER .Filed Aug. 25, 194:5 s sheets-sheet s mi ifm f Patented Oct. 1, 1946 PROPELLER SPINNER Frank Morgan'Owner, Bristol, England, assignor, by mesne assignments, to Rotol Limited,

f Y Gloucester, England Application August 23, 1943, Serial'No. 499,674- K `rIn Great Britain March 23, 1942 This invention concerns' spinners for propel- 1ers having variable-pitch bladesand has for its object to provide a spinner which in conjunction with the propeller blades passing therethrough will reduce the drag -thereof to a minimum.

The invention is of particularA application to propellers which have cus fitted to thershank ofthe propeller blades to impart an aerofoil formto the part of the propeller blades adjacent `the spinner. Such propellers suffer Yfrom the ldisadvantage'that if'the edge of the cuff which isadjacent the spinner (hereinafter referred to as the lower edge of thecuif)l is not in close proximity thereto `over the operating range of the propeller, that is from the fine pitch position to the feathered position, the air ceases to flow over the spinner and around the cuifswith a minimum of turbulence and drag. To overcome this disadvantage various proposals have been made; in one the lower edge of the cuif entered a circular nat-bottomed dished recess formed in the spinner; in another a flat-topped platform was-raised above the spinnerline and over this the lower edge of the cuif rotated, the distance Abetweerrthe lower edge of thelcuif andthe platform being a minimum and the same for al1 positions of the propeller; p-These proposals whilst eliminating the drag produced by poor mating of the cuff and the spinner are unsatisfactory in that the recess or the platform produces considerable drag itself.

According to the present invention the combination of a propeller spinner and a propeller is characterized in that the spinner contour is modiedadjacent eachpropeller blade cut-out so that over the operating range of the blade that part Vthereof which moves over the spinner surface is maintained in close proximity thereto.

Preferably the spinner contour is modified by providing a portion raised above the spinner line on Vthe Yside of the cut-out vadjacentthe spinner nose, said portion having aY surface of revolution formed by the rotation about the longitudinalaxis of the propeller blade of a line inclined to said axis in the same sense as the spinner line.

The raised portion is faired into the spinner in order to ensure that streamline iiow will take place over the spinner and around the base of the propellerblade or cuffs. The raised portion is also faired into a surface disposed on the other side of the cut-out, this surface preferably being flat and normal to the longitudinal axis of the propeller blade.

5 claims. (c1. 17o-159) The propeller or the lower edge of the cuff is shaped to similar outline as 'the modied spinner contour and is spaced therefrom by the smallest permissible amount.

Specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a side view of a propeller spinner constructed in accordance with the invention, part being shown in section.

'Figures 2 and 3 are similar views showing'alternative forms the invention may take.

Figure 4 is a front elevation of a propeller constructed according to the invention.

Figure 5 shows the'improved propeller in which the blades '30 t lthrough sleeves I1 into the spinner I0, the nose of which is indicated at I3.

The spinner I0 is adapted for use with a propellerhaving yfour blades each of which receives a cuff to impart an aerofoil form to the shank of the blade adjacent the spinner. Each blade protrudes through a cut-out Il formed in the wall of the spinner.

In the embodiment shown in Figure 1 a raised convex surface I2 is formed around the forward half of each cut-out, that is on the side thereof adjacent the spinner nose I3.l This surface extends in a direction away from the spinner nose and around the rear half of the cut-out as a flat surface I4 normal to the longitudinal axis I5 of the propeller blade. The atand convex surfaces (I4 and I2 respectively) are suitably faired into each other and into the spinner surface.

The lower edge I6 rof each cuif I1 is of similar outline lto the spinner contour, that is the half thereof directed towards the spinner nose is concave (I 8)v andthe half remote therefrom is flat (I9).

With this construction the lower edge of each cuff can belmade accurately tov follow the modified spinnery contour over the'operating range of the `propeller (that is between lines a--a and b b) 'but not when the propeller blades are moved tothe zero pitch position (indicated'at c-c) when the rear part of each cuff leaves the flat raised surface which is restricted in its dimensions circumferentially of the spinner for physical reasons, and the distance between the rear part of its lower edge I6 and the spinner contour increases with consequent increase in drag. This is no disadvantage since when the blades assume the negative pitch position it is desirable to have ahigh value for the drag.

As shown in Figure 2 the convex surface I2 of Figure 1 is replaced by a conic surface 20, the flat surface I4 being retained.

Spinners in which the slope of the spinner line is considerable may require a raised portion of excessive height and accordingly in an alternative construction particularly applicable to such spinners and shown in Figure 3, there is provided adjacent the forward half of the cut-outs Il a raised convex surface 2| whilst adjacent the rear half of the cut-outs, there is provided a depression having a concave surface 22. The surfaces 2I, 22 are faired into each other and into the spinner whilst the cuffs are provided with a modified lower edge to match the spinner.

In the construction shown in Figure 3 the surfaces 2I may be replaced by a conc surface and/ or the surface 22 by an inverted conc surface.

2. The combination of a propeller having blades each rotatable about its own longitudinal axis, and a spinner mounted on said propeller and having cut-outs through which the blades project, said spinner being formed at the Side of each cut-out adjacent the spinner nose with a portion raised above the spinner line and generated as a surface of revolution by the rotation about the longitudinal axis of the blade, of a line inclined to said axis in the same sense as the spinner line, a flattened surface formed on the Aspinner adjacent said raised portion at the side thereof remote from the spinner nose, said flattened portion being normal to the longitudi- It will be observed from the Afigures that sur- 'i faces I2, 20, 2l and 22 are generated by aline of appropriate shape which is rotated about the longitudinal axis I5 of the propeller and is inclined thereto in the same sense as the spinner line.

The spinner contour may be modiiied as above referred to by a pressing operation which imparts the desired shape thereto or alternatively the part of the shape in which it is desired to modify the spinner may be formed and subsequently secured as by riveting or welding to the spinner.

The invention is capable of application to propellers and spinners whether cuffs be tted to the propeller blades or not. When the propeller blades are of metal, steel or magnesium, cuffs are normally tted. vIf the propeller blades are of wood the aerofoil `section of the blade may be continued so far towards the root of the blade as not to warrant the fitting of cuffs. In the first case referred to, the culic would cooperate with the inclined portion of the spinner and in the second case referred to the blade itself would perform this function. Accordingly, the term blades as used in the claims refer to propeller blades with or without cuffs, the cuffs being considered to form a part of the blade and not to be a separate entity.

I claim:

1. The combination of a propeller having blades each rotatable about its own longitudinal axis, and a spinner mounted on said propeller having cut-outs through which the blades project, said spinner being shaped to provide on the side of each cut-out adjacent the spinner nose, a portion raised above the general contour line of the spinner, said portion having a surface of revolution formed by the rotation about the longitudinal axis of a blade, of a line inclined to said axis in the same sense as the spinner line, a flattened portion adjacentveach cutout on the side away from the spinner nose, said flattened portion being normal to the longitudinalaxis of the blade and faired into said raisedy portion, said blades having root portions shaped to .overlap said raised portion in a direction axially of the' blade.

nal axis of the propeller blade, and being merged into the contour of the spinner at the end remote from 'the nose thereof by a surface generated by rotation about the longitudinal axis of the 'blade of a line inclined to the spinner axis at an angle greater than the adjacent part of the spinner surface, said blades being `shaped at their root portions to overlap said raised portion in a direction axially of the blades.

3. The combination of a propeller having blades each rotatable about its own longitudinal axis, a spinner mounted on said propeller and having cut-outs through which the blades project, said spinner being shaped to provide on the ,side of the cut-out adjacent the spinner nose, a portion raised above the general contour line, said portion .having a surface of revolution formed by the rotation about the longitudinal axis of the propeller-blade of a line inclined to said axis in the same sense as the spinner line, anda cuff secured on each blade adjacent the spinner, said cuff on each of said blades having a radially inward extension on its forward 4edge overlapping said raised portion.

4. The combination of a propeller having blades each rotatable about its own longitudinal axis, a spinner mounted on said propeller and having cut-outs through which the blades project, and having a portionl surrounding each cut-out on the side adjacent the spinner nose, said portion being inclined to the spinner axis at a larger angle than the adjacent part of the spinner and being generated by rotation ofy a line about the blade axis, said' blades havingroot ends overlapping the inclined portion of the spinner in a direction axially of the blades.

5. The combination of a propeller having blades each rotatable about its own longitudinal axis, a spinner mounted on said 4propeller and having cut-outs through which the bladesrv project, and having a portion surrounding each cut-out on the side adjacent the spinner nose, said portion being inclinedvto the spinner axis at a larger angle than the adjacenty part of the spinner and being generated by rotation about'thev blade axis of a straight line inclined to the spinner axis at a larger `angle thany the'adjacent surface of the spinner to provide a conical surface, said blades having root portions l*overlapping Ythe in- @lined portions in `directions axiauyof vthe blades.

FRANK MORGAN OWNER.