Aircraft propellers

An aircraft propeller taper bore insert apparatus includes a tapered outer surface, the outer surface dimensioned and configured to fit within and be of substantially a same size and shape as an aircraft propeller taper bore or an aircraft propeller balancing tube, and an inner surface, the inner surface defining an inner cavity configured to receive a balancing medium, the inner surface comprising a plurality of retention formations arranged thereon, and the plurality of retention formations being configured to support the balancing medium.

BACKGROUND OF THE INVENTION

This invention is generally related to propeller systems, and more particularly, example embodiments of the present invention are related to systems for balancing aircraft propellers.

Propeller systems typically include a hub to which two or more propeller blades are coupled. Rotation of the hub causes the blades to rotate. In order for the rotation to be smooth the blades are typically balanced.

BRIEF DESCRIPTION OF THE INVENTION

According to an example embodiment of the present invention, an aircraft propeller taper bore insert apparatus includes an outer surface and an inner surface. The outer surface is dimensioned and configured to fit within an aircraft propeller taper bore or an aircraft propeller balancing tube, the inner surface defines an inner cavity configured to receive a balancing medium, the inner surface comprises a plurality of retention formations arranged thereon, and the plurality of retention formations are configured to support the balancing medium.

According to another example embodiment of the present invention, a propeller blade includes a propeller body defining a taper bore cavity, a balancing tube arranged within the taper bore cavity, and a taper bore insert. The taper bore insert includes an outer surface and an inner surface. The outer surface is dimensioned and configured to fit within the balancing tube, the inner surface defines an inner cavity configured to receive a balancing medium, the inner surface comprises a plurality of retention formations arranged thereon, and the plurality of retention formations are configured to support the balancing medium.

According to yet another example embodiment of the present invention, an aircraft propeller system includes a propeller hub, a first aircraft propeller blade arranged on the propeller hub, and a second aircraft propeller blade arranged on the propeller hub opposing the first aircraft propeller blade. The first aircraft propeller blade and the second aircraft propeller blade each include a propeller body defining a taper bore cavity, a balancing tube arranged within the taper bore cavity, and a taper bore insert. Each taper bore insert includes an outer surface and an inner surface. Each outer surface is dimensioned and configured to fit within the balancing tube, the inner surface defines an inner cavity configured to receive a balancing medium, the inner surface comprises a plurality of retention formations arranged thereon, and the plurality of retention formations are configured to support the balancing medium.

DETAILED DESCRIPTION OF THE INVENTION

Conventionally, to achieve proper balance moments in propellers used in aircraft, lead wool is positioned within a hollow core of a taper bore portion of propellers. It should be appreciated that lead is generally considered environmentally unfriendly and thus aircraft propeller systems using lead wool may prove difficult to properly service and/or dispose of.

Example embodiments of the present invention provide novel aircraft propeller taper bore balancing systems which can negate or reduce the need for lead wool to achieve proper balance of the blades. A technical effect of one embodiment includes the use a variety of different materials according to a particular availability of material without resorting to the use of environmentally unfriendly materials to balance a propeller system.

Turning toFIG. 1, an aircraft propeller taper bore insert is illustrated. The taper bore may be an interior portion of an aircraft propeller's blade. As illustrated, the taper bore insert100includes an outer surface101and an inner surface102. As illustrated, the outer surface101may be shaped and dimensioned to be of substantially the same size and shape as a conventional propeller taper bore. That is, the taper bore insert100can be configured such that it may be positioned within a taper bore within a propeller blade. The inner surface102defines an inner cavity103. Furthermore, the inner surface102may include a plurality of retention formations104arranged thereon.

As shown, the retention formations104may protrude inwardly from the inner surface102into the inner cavity103. The retention formations104may extend along the entire inner surface102forming “ribs,” or may be segmented or finger-like protrusions. Alternatively, the retention formations104may be grooves or groove-like indentation formations formed in the inner surface102. Also, the retention formations104may include discontinuous indentations (e.g., dimple-like features) comparable to the discontinuous protrusions noted above, or complimentary to the linear features noted for both protrusions and indentations (i.e., ribs and grooves).

According to example embodiments, the retention formations104provide a mechanical support arrangement for allowing adhesion of a filler material thereto such that a balancing medium may be dispersed and supported within the inner cavity103. For example, such is illustrated inFIG. 2.

As illustrated inFIG. 2, balancing medium202comprises a plurality of particles201. For example, particles201may be formed of any suitable material allowing for proper balancing of an aircraft propeller, for example, steel shot, copper shot, steel pellets, copper pellets, sand, ceramic pellets, rocks, or any other suitable material. Each particle may be of relatively the same size or may be of different sizes.

The balancing medium202further comprises a filler material203filling the expanses between particles. The filler material203may be a binder or matrix allowing for adhesion to the discreet particles201and inner cavity of the taper bore insert, or simply a mechanical interference fit between the balancing medium and the taper bore insert, and may include an adhesive, thermoplastic, elastomer, thermoset polymeric resin, gel, sealant, wax or any other suitable material configured to restrict movement of the particles201within the inner cavity103. Although not particularly illustrated, it should be understood that the taper bore insert100may be sealed or unsealed depending upon any desired implementation. For example, a sealing plug, cap, or insert may be arranged to compress and seal the balancing medium202. Further, a sealing plug or plug-like member, cap, threaded sealing member, or insert may be positioned to seal the entire inner cavity103.

Therefore, according to example embodiments, an aircraft propeller taper bore insert may be filled with a balancing medium202to achieve a proper balance moment of an aircraft propeller. Hereinafter, additional example embodiments more clearly illustrating installation of taper bore inserts within aircraft propellers are provided with reference toFIGS. 3-5.

Turning toFIG. 3, a portion of an aircraft propeller blade is illustrated. The aircraft propeller blade300includes a propeller body301and a support body302. The propeller blade300further includes a support medium320(e.g., cushion or foam) arranged within the support body302proximate the propeller body301. The support body302includes pitch control formation321disposed to allow modification of a pitch of the propeller body301.

As further illustrated, the propeller body301includes a taper bore surface304defined in a cavity303. The cavity303may be filled with a cushioning material or may be relatively empty. Furthermore, the cavity303may be solid, for example, formed of any suitable lightweight composite material, or metals such as aluminum, titanium, or any suitable metal alloy. The taper bore surface304further defines an internal taper bore cavity including balancing tube305arranged therein. The balancing tube305may be formed of any suitable material, including lightweight composite materials and/or metals such as aluminum, titanium, or any suitable metal alloy. The balancing tube305defines cavity350configured to receive a taper bore insert.

As further illustrated, the propeller blade300includes the taper bore insert306arranged within the cavity350. The taper bore insert306includes an outer surface361and an inner surface362. As illustrated, the outer surface361may be shaped and dimensioned to be of substantially the same size and shape the cavity350. The inner surface362may define inner cavity363. Furthermore, the inner surface362may include a plurality of retention formations364arranged thereon.

As shown, the retention formations364may protrude within the inner cavity363. The retention formations364may extend along the entire inner surface362forming “ribs,” or may be segmented or finger-like protrusions. Alternatively, the retention formations364may be grooves or groove-like indentation formations formed in the inner surface362. Also, the retention formations364may include discontinuous indentations (e.g., dimple-like features) comparable to the discontinuous protrusions noted above, or complimentary to the linear features noted for both protrusions and indentations (i.e., ribs and grooves).

According to example embodiments, the retention formations364provide a mechanical support arrangement for allowing adhesion and support of balancing medium372comprising filler material373and particles371therein. The balancing medium372may be substantially similar to the balancing medium202described above.

Thus, as described above, example embodiments provide aircraft propellers comprising a propeller body, a support body, and a taper bore cavity disposed within the propeller body. The taper bore cavity may include a balancing tube arranged therein. Further, the balancing tube may define a cavity configured to receive a taper bore insert. The taper bore insert may be substantially similar to the insert100illustrated inFIGS. 1-2and the insert306ofFIG. 3. However, according to some example embodiments, a taper bore insert may be omitted, and a balancing tube may be formed and configured to retain a balancing medium therein.

For example, turning toFIG. 4, a portion of an aircraft propeller blade is illustrated. The aircraft propeller blade400includes a propeller body401and a support body402. The propeller blade400further includes a support medium420(e.g., cushion or foam) arranged within the support body402proximate the propeller body401. The support body402includes pitch control formation421disposed to allow modification of a pitch of the propeller body401.

As further illustrated, the propeller body401includes a taper bore surface404defined in cavity403. The cavity403may be filled with a cushioning material or may be relatively empty. The taper bore surface404further defines an internal taper bore cavity including balancing tube405arranged therein. The balancing tube405may be formed of any suitable material, including lightweight composite materials and/or metals such as aluminum, titanium, or any suitable metal alloy.

As further illustrated, the balancing tube includes an outer surface451and an inner surface452. As illustrated, the outer surface451may be shaped and dimensioned to be of substantially the same size and shape the inner cavity450. The inner surface452may define inner cavity450. Furthermore, the inner surface452may include a plurality of retention formations454arranged thereon.

As shown, the retention formations454may protrude within the inner cavity450. The retention formations454may extend along the entire inner surface452forming “ribs,” or may be segmented or finger-like protrusions. Alternatively, the retention formations454may be grooves or groove-like indentation formations formed into the inner surface452. Also, the retention formations454may include discontinuous indentations (e.g., dimple-like features) comparable to the discontinuous protrusions noted above, or complimentary to the linear features noted for both protrusions and indentations (i.e., ribs and grooves).

According to example embodiments, the retention formations454provide a mechanical support arrangement for allowing adhesion and support of balancing medium472comprising filler material473and particles471therein. The balancing medium472may be substantially similar to the balancing medium202and372described above.

Thus, as described above, example embodiments provide aircraft propellers comprising a propeller body, a support body, and a taper bore cavity disposed within the propeller body. The taper bore cavity may include a balancing tube arranged therein. Further, the balancing tube may include an inner surface having a plurality of retention formations arranged thereon configured to support a balancing medium within the balancing tube. Thus, proper balance moment of a propeller may be achieved.

Turning now toFIG. 5, an aircraft propeller system is illustrated. As shown, the system500includes a first propeller blade501and a second propeller blade502supported by propeller hub513. The first propeller blade501and the second propeller502may be substantially similar to propeller blades300or400. For example, the first propeller blade501may include a taper bore cavity511defined therein, and configured to receive the balancing tube305and taper bore insert306; or alternatively, the balancing tube405. Furthermore, the second propeller blade502may include a taper bore cavity512defined therein, and configured to receive the balancing tube305and taper bore insert306; or alternatively, the balancing tube405. Thus, the system500may be balanced using any of the balancing mediums described herein, and may therefore avoid the use of lead wood as in conventional systems.

Alternatively, the first propeller blade501and the second propeller blade502may include any conventional propeller including a taper bore insert cavity or any suitable cavity configured to receive the taper bore insert100.

Furthermore, although particularly illustrated as including two propeller blades, it should be readily understood that example embodiments may include propeller systems with any desired number of propeller blades.