Aircraft and its manufacture

Abstract

Aircraft with the following characteristics: - the aircraft has wings (10) with integrated ducted fans (11-20) and - the ducted propellers (11-20) each have a duct (11, 14) with a stiffness ring (17, 18, 19), characterized by the following feature: - the stiffness ring (17, 18, 19) consists of stiffness boxes (17, 18) and circular arc-shaped partial rings (19).

Description

[0001] The present invention relates to an aircraft, in particular a fully electric, vertical take-off and landing (VTOL) aircraft, and to an advantageous method for producing such an aircraft. State of the art

[0002] In aerospace engineering, VTOL refers to any type of aircraft, drone, or rocket capable of taking off and landing essentially vertically without a runway. This collective term is used in a broad sense below, encompassing not only fixed-wing aircraft with wings, but also rotary-wing aircraft such as helicopters, gyroplanes, and helicopters, as well as hybrids such as compound helicopters or combination helicopters, as well as convertible aircraft. It also includes aircraft capable of particularly short takeoff and landing (STOL), short takeoff and vertical landing (STOVL), or vertical takeoff and horizontal landing (VTHL).

[0003] EP 2 193 993 A2 discloses a propeller shroud which is essentially composed of two annular components.

[0004] WO 2005 / 032939 A1 proposes to produce a propeller shroud in segmental construction according to a modular system.

[0005] US 7 712 701 B1 and CN 205 770 158 U describe propeller shrouds made from individual circumferential segments.

[0006] DE 20 2015 003 815 U1 discloses the subject matter of the preamble of claim 1, from which the present invention is based. DE 12 00 140 A, DE 12 09 001 A, and DE 12 05 392 A show comparable arrangements. Disclosure of the invention

[0007] The invention provides an aircraft, in particular a fully electric aircraft capable of vertical takeoff and landing in the above sense, and a method for producing such a vehicle according to the independent claims.

[0008] The inventive approach is based on the insight that a VTOL aircraft that can be used in urban environments requires propulsion units in different positions and orientations that are capable of handling each flight phase (takeoff, transition, cruise and landing) and withstanding any elastic deformation under stress, but on the other hand do not exceed a manageable number of individual parts.

[0009] Instead of a free-running rotor, ducted fans integrated into the wing are used to provide the aircraft's lift, similar to those found in hovercraft and airboats outside of aeronautical technology. The cylindrical housing of the air duct—hereafter referred to as the duct—reduces the thrust losses caused by turbulence at the blade tips of such a ducted propeller.

[0010] According to the invention, this jacket carries a rigidity ring constructed in a modular manner - i.e. according to a building block or modular principle - which is composed of rigidity boxes and circular arc-shaped partial rings in order to save costs and yet give the jacket a high geometric accuracy and rigidity.

[0011] Further advantageous embodiments of the invention are specified in the dependent patent claims. Thus, several installation variants of the casing can be provided, with the casing in each variant carrying two uniform partial rings. The number of identical parts of the stiffness ring can be maximized in this way. Short description of the drawings

[0012] An embodiment of the invention is illustrated in the drawings and is described in more detail below. Fig. 1 shows the isometric view of a wing with partially transparent planking and outer skin. Fig. Figure 2 shows the isometric view of the ducted propellers of the wing without engine. Fig. 3 shows one of the Fig. 2 corresponding view from an elevated perspective. Fig. 4 shows the isometric view of a propeller with partially transparent inlet and outlet. Fig. Figure 5 shows the front view of two shell parts in different installation variants. Fig. Figure 6 shows an isometric view of two shells with partially transparent inlet and outlet. Fig. 7 to 9 illustrate the joint between the shell and the guide vane. Embodiments of the invention

[0013] Fig. Figure 1 illustrates the structure of a wing (10) for an optionally fully autonomously or manually controlled aircraft, which is approximately divided into quadrants by spars and ribs. A ducted propeller is integrated into each of these quadrants, the propeller's guide vanes (12) arranged within the wing (11) supporting a central electric motor (13). For this purpose, the three cylindrical electric motors (13) are bolted radially to the respective guide vanes (12) in such a way that their struts, made of carbon or carbon fiber reinforced plastic (CFRP), can support the electric motor (13) from opposite sides in an axially and rotationally symmetrical arrangement.

[0014] In the illustrated configuration, two of the struts of each guide vane (12) run parallel to each other in the direction of flow of the blade (10) and flank the associated electric motor (13) tangentially. Two beams joined to these cheeks complement the beams of the other cheek, diametrically opposite the motor (13), to form a St. Andrew's or diagonal cross, stiffening the electric motor (13) such that the guide vane (12) absorbs all horizontal forces in the motor plane. As the illustration suggests, the struts of the guide vane (12) have a width that roughly corresponds to the height of the electric motor (13).

[0015] The Fig. 2 and Fig. 3 illustrate the different installation variants (X, Y) of the casing (11). This variant formation is achieved according to the invention by the Fig. 4 based on the installation variant Y, according to which the casing, which in this case is composed of inlet modules (11) and outlet modules (14), is stiffened by a multi-part ring (17, 18, 19).

[0016] This stiffness ring (17, 18, 19) in turn is composed of comparatively high first stiffness boxes (17), flatter second stiffness boxes (18) and two circular arc-shaped partial rings (19) connecting the first stiffness box (17) on diametrically opposite sides of the shell (11, 14) to the second stiffness box (18).

[0017] The reason for the different heights of the first (17) and second stiffness boxes (18) can be seen from the illustration according to Fig. 5: Here, the outlet module (14) also has a height that can be varied over its circumference, which requires an adapted shape of the stiffness boxes (17, 18) provided at opposite circumferential positions.

[0018] Fig. Figure 6 illustrates the possible combinations of the described individual elements to form stiffness rings (17, 18, 19) in two different installation variants (X, Y). The universal interfaces of the three modules allow two of the uniform partial rings (19) for each of the shells (11, 14) to be connected to one of the first stiffness boxes (17) and second stiffness boxes (18) in any desired arrangement. In the present configuration, for example, two adjacent shells (11, 14) of different installation variants (X, Y) are aligned with each other such that the first stiffness boxes (17) of the two shells (11, 14) face toward each other, while their second stiffness boxes (18) face away from each other.

[0019] A summary of the Fig. 7, Fig. 8 and Fig. Figure 9 illustrates, using two exemplary shells (here: 11, 14, 19) of both installation variants, how the associated guide grid (12) can finally be inserted into the outlet modules (14) from below by means of radial recesses (20) of the latter, as shown in the illustration.

[0020] The individual propeller shells (11, 14) can, for example, be composed of honeycomb cores with inserts and then preferably coated with multiple layers of CFRP. In this context, this refers to any composite material in which carbon fibers are embedded in a plastic matrix, which serves to bond the fibers and fill the interstices. In addition to conventional epoxy resin, other thermosets or thermoplastics can also be used as the matrix, without departing from the scope of the invention.

[0021] In the present embodiment, the electric motor (13 - Fig. 1) as an air-cooled internal rotor with integrated control. It is understood that in an alternative embodiment, for example, an external rotor or liquid cooling may be used without departing from the scope of the invention. Further exemplary options are disclosed, for example, by DUFFY, Michael, et al. "Propulsion scaling methods in the era of electric flight." In: 2018 AIAA / IEEE Electric Aircraft Technologies Symposium (EATS). IEEE, 2018. pp. 1-23.

Claims

[1] Aircraft with the following characteristics: - the aircraft has wings (10) with integrated ducted propellers (11-20) and - the ducted propellers (11-20) each have a casing (11, 14) with a stiffness ring (17, 18, 19), characterized by following feature: - the stiffness ring (17, 18, 19) consists of stiffness boxes (17, 18) and circular arc-shaped partial rings (19). [2] Aircraft according to claim 1, characterized by following features: - the stiffness boxes (17, 18) comprise first stiffness boxes (17) and second stiffness boxes (18) and - the first stiffness boxes (17) differ from the second stiffness boxes (18) in their height. [3] Aircraft according to claim 2, characterized by following features: - the ducted propellers (11-20) have different installation variants (X, Y) of the duct (11, 14) and - the first stiffness boxes (17), the second stiffness boxes (18) and the partial rings (19) are uniform in all installation variants (X, Y). [4] Aircraft according to claim 2 or 3, characterized by following features: - in each installation variant (X, Y), the casing (11, 14) carries one of the first stiffness boxes (17), one of the second stiffness boxes (18) and two of the partial rings (19) and - the two partial rings (19) connect the first stiffness box (17) on diametrically opposite sides of the shell (11, 14) with the second stiffness box (18). [5] Aircraft according to claim 4, characterized by following feature: - two adjacent shells (11, 14) of different installation variants (X, Y) are aligned with each other in such a way that the first stiffness boxes (17) of the two shells (11, 14) face each other. [6] Aircraft according to one of claims 2 to 5, characterized byfollowing feature: - the first stiffness boxes (17), the second stiffness boxes (18) and the partial rings (19) have universally combinable connection points. [7] Aircraft according to one of claims 1 to 6, characterized by following feature: - the shells (11, 14) are each composed of inlet modules (11) and outlet modules (14) and - the outlet modules (14) carry the stiffness rings (17, 18, 19). [8] Aircraft according to one of claims 1 to 7, characterized by following features: - the shells (11, 14) have honeycomb cores with inserts and - the jackets (11, 14) are coated with multiple layers of carbon fibre reinforced plastic. [9] Aircraft according to one of claims 1 to 8, characterized by following features: - the ducted propellers (11-20) each comprise a guide vane (12) and an electric motor (13) carried by the guide vane (12) and - the outlet modules (14) have recesses (20) for inserting the guide grid (12) into the respective casing (11, 14). [10] A method for manufacturing an aircraft according to any one of claims 1 to 9, characterized by following features: - the shells (11, 14) are each composed of the stiffness boxes (17, 18) and partial rings (19) and - the ducted propellers (11-20) are inserted into the blades (10) in different installation positions.

Images