Patent Description:
Due to safety regulations, the cargo and/or accessory compartment of an aircraft must be fire resistant and gas tight to the extent of fire starving capability and it must keep smoke emissions to a neglectable level in terms of flight safety. Conventional liners used for cargo and/or accessory compartments are made of several components of a rigid monolithic composite material.

A liner according to the preamble of claim <NUM> is know from <CIT>. Another liner is known from <CIT>.

According to a first aspect of the present invention defined in claim <NUM>, a liner for a cargo and/or accessory compartment of an aircraft is provided, the liner being fire-resistant and gas tight to the extent of fire starving capability and the liner keeping smoke emissions to a neglectable level in terms of flight safety, wherein the liner comprises a bag of fire-resistant and gas tight flexible fabric. This offers a considerable reduction of weight compared to conventional design, allows the prefabrication of the complete liner outside the aircraft and therefore facilitates production and reduces installation time, and provides an improved gas-tightness as there are zero joints to be sealed during installation. The invention is particularly applicable but not limited to an electric VTOL (vertical take-off and landing) aircraft because a low weight is absolutely crucial with this type of aircraft.

According to the first aspect of the present invention, the bag is adapted to form at least a ceiling and sidewalls of the cargo and/or accessory compartment.

According to a preferred embodiment of the present invention, the bag is fashioned to be suspended from a fuselage structure of the aircraft in the manner of an inner tent. This embodiment offers the advantage of an easy installation of the liner.

According to another preferred embodiment of the present invention, the liner comprises at least one reinforcing batten for stabilizing or stiffening at least a portion of the bag. This embodiment adds to a stable and yet lightweight construction. Preferably, the reinforcing batten(s) is/are arranged at the outside of the bag such that the inside walls of the cargo and/or accessory compartment are smooth and the battens do not interfere when for example luggage is loaded or unloaded from the cargo and/or accessory compartment.

According to another preferred embodiment of the present invention, the at least one reinforcing batten is received in lugs of the bag. This embodiment offers a very easy way of stabilizing or stiffening portions of the bag using battens.

According to the first aspect of the present invention, the bag is adapted to form a floor of the cargo and/or accessory compartment, wherein the liner further comprises a floor frame for spanning a floor portion of the fabric. This embodiment offers a very lightweight construction since the floor of the cargo and/or accessory compartment is mainly formed by the fire-resistant and gas-tight flexible fabric. The floor frame is necessary in order to span and thereby stabilize the fabric.

Preferably, the floor frame is adapted to be attached to a fuselage structure of the aircraft, for example via brackets that are part of or connected with the fuselage of the aircraft.

Preferably, the frame is made of a carbon fiber reinforced polymer. This adds to a lightweight construction.

According to the first aspect of the present invention, the floor portion of the fabric is a separate piece from a remainder of the bag such that the floor portion is replaceable independently from the remainder of the bag with or without the floor frame. This facilitates maintenance and repair of the cargo and/or accessory compartment. For example, the floor portion may be detachable from the floor frame or the floor frame and the floor portion of the fabric may be detachable from the remainder of the bag.

According to an alternative embodiment not part of the present invention, the liner may comprise a rigid floor panel that is attached to the bag and that is attachable to a fuselage structure of the aircraft, for example via brackets that are part of or connected to the fuselage of the aircraft. This embodiment provides an improved stability of the floor such that heavier and/or sharp objects/luggage may be placed on the floor of the cargo and/or accessory compartment.

According to a particularly stable embodiment that is not part of the invention, the rigid floor panel is pan-shaped and comprises a bottom plate and a sidewall protruding from the bottom plate. This embodiment guarantees that the enclosing outer fuselage structure of the aircraft is protected in a floor area of the cargo and/or accessory compartment, for example if heavy and/or sharp objects slide to the side or press against the sidewall of the cargo and/or accessory compartment.

Preferably, the rigid floor panel is made of a sandwich material. This also adds to a stable and lightweight construction. It is particularly preferred if the rigid floor panel is made from a honeycomb material.

According to yet another preferred embodiment that is not part of the invention, the rigid floor panel may be protected by a protective floor cover. Preferably, the floor cover is attached to the floor panel using double sided tape. Furthermore, the protective floor cover is preferably made from a non-textile material.

According to another preferred embodiment that is not part of the invention, an edge of the rigid floor panel is protected by a scuff plate at least in a loading area of the cargo and/or accessory compartment. Thus, the loading edge of the cargo and/or accessory compartment can be made particularly robust. Preferably, the scuff plate is made of a metal material.

According to another preferred embodiment of the present invention, the bag is provided with at least one opening for a smoke detector or a continuous-loop system and/or a light and/or a floor frame fastener and/or a floor panel fastener. The opening(s) is/are preferably sealed around cables and fasteners using jubilee clips or similar.

According to another preferred embodiment of the present invention, the fabric is a silicone coated glass and/or aramid fabric providing the necessary strength and flame resistance. However, any other fabric made from high tensile strength flexible fibers that provides the necessary strength and flame resistance may be used.

According to yet another preferred embodiment, the liner is provided with a restraint net arranged within the bag of fire-resistant and gas tight flexible fabric. The restraint net is used to secure the cargo to the rigid floor panel or to the floor frame and/or floor portion of the fabric.

Preferably, the restraint net is constructed from either polyester braid or webbing formed into a matrix of strap members.

If the restraint net is constructed from polyester braid, the polyester braid is preferably spliced together at each intersection to obtain the required profile. If the restraint net is constructed from webbing, the webbing is preferably stitched together at each intersection.

Preferably, suitable attachment fittings are provided to secure the restraint net to the rigid floor panel or to the floor frame and/or floor portion of the fabric.

The attachment fittings are preferably quick release fittings to allow the restraint net to be removed with minimal effort. In order to save weight it may be possible to permanently attach the restrain net more securely in certain locations, i.e. at the most forward attachment locations, thus reducing the amount of metalwork required.

At the rear of the restraint net, i.e. at a boot lid of the cargo and/or accessory compartment, adjustment buckles are preferably built in to allow the restraint net to be tensioned down onto the cargo, therefore minimizing movement during flight.

To facilitate loading and unloading, the net is preferably suspended by elasticated bungees, so when un-tensioned, the cargo compartment area is maintained and the net is lifted away from the cargo to facilitate loading and unloading.

According to yet another embodiment of the present invention, the bag comprises a loading opening through which luggage and/or other cargo items can be loaded into or unloaded from the cargo and/or accessory compartment, wherein portions of the bag around the loading opening are foldable such that the loading opening may be closed by folding said portions together.

According to a second aspect of the present invention, an aircraft comprising a cargo and/or accessory compartment is provided, wherein the cargo and/or accessory compartment is formed by a liner according to the first aspect of the invention, in particular according to any or all of the above mentioned embodiments of the first aspect.

According to a preferred embodiment, a sidewall of the liner is spanned at a distance from an enclosing outer fuselage structure of the aircraft. Thus, the enclosing aircraft fuselage structure is protected from objects deflecting the sidewalls of the bag.

According to a particularly preferred embodiment, at least one impact dampening pad is arranged between the sidewall of the liner and the enclosing outer fuselage structure of the aircraft. This guarantees maximum protection against objects deflecting the sidewalls of the liner/bag.

Preferably, the impact dampening pad is made of a foam, in particular of an expanded polypropylene (EPP).

According to another preferred embodiment, the cargo and/or accessory compartment is accessible from the outside through a boot lid of the aircraft, wherein the bag of fire-resistant and gas tight flexible fabric is provided with an opening in the area of the boot lid.

Preferably, an outer fire-resistant sealing is provided between a door structure of the boot lid and the fuselage structure.

Preferably, an inner fire-resistant sealing is provided between the door structure of the boot lid and the bag. Preferably, an edge of the bag around the opening of the bag is attached to and lying flat against the fuselage structure.

Preferably, the door structure of the boot lid is lined with the same fire-resistant and gas tight flexible fabric that the bag is made of.

According to a third aspect of the present invention, a method of lining a cargo and/or accessory compartment of an aircraft with a liner is provided, the method comprising the steps of:.

According to a preferred embodiment, the liner is attached to the fuselage structure at fastening points provided at the ceiling and at the floor of the cargo and/or accessory compartment.

Embodiments of the present invention will be explained in more detail further below with reference to the drawings in which:.

In the following, the same parts are designated by the same reference signs. If a Figure comprises reference signs which are not addressed in detail in the associated description of the Figure, reference is made to the preceding or following descriptions of the Figures.

<FIG> shows a side view of an aircraft <NUM>. By way of example, the aircraft <NUM> may be an electric vertical take-off and landing aircraft (eVTOL). The aircraft <NUM> thus moves in a basically vertical direction during takeoff and landing and in basically horizontal direction during transition flight. However, the invention is not limited to such a type of aircraft. The aircraft <NUM> comprises a fuselage, a pair of wings arranged at or near the rear end of the aircraft and a cargo and/or accessory compartment <NUM> that is also arranged at the rear of the aircraft <NUM> and that is accessible from the outside through a pivotable boot lid <NUM>.

<FIG> shows the aircraft <NUM> in a perspective rear view with the boot lid <NUM> in an open position such that luggage <NUM> and/or other cargo items can be loaded into or unloaded from the cargo and/or accessory compartment <NUM>.

<FIG> shows a detail longitudinal section view of the aircraft shown in <FIG> with a cargo and/or accessory compartment <NUM> according to a first embodiment that is not part of the invention. <FIG> shows a cross section view of the cargo and/or accessory compartment <NUM> according to the first embodiment along section line IV-IV indicated in <FIG>. The cargo and/or accessory compartment <NUM> is formed by a liner that comprises a bag <NUM> of fire resistant and gas tight flexible fabric. The fabric is preferably a silicone coated glass fabric. The bag <NUM> forms the ceiling <NUM> and the sidewalls <NUM> of the cargo and/or accessory compartment <NUM>. It is suspended from the fuselage structure <NUM> of the aircraft in the manner of an inner tent using suitable fasteners <NUM>.

A ceiling portion of the bag <NUM> may be stabilized by several reinforcing battens <NUM>, one of which is shown in <FIG>. The reinforcing battens <NUM> may run along the outside of the bag <NUM> and may be received in lugs <NUM> of the bag <NUM> as shown in <FIG>.

The floor <NUM> of the liner or compartment <NUM> is formed by a rigid floor panel <NUM> attached to a lower end of the bag <NUM> of fire resistant and gas tight flexible fabric, for example by glueing. The floor panel <NUM> is preferably made of a sandwich material, in particular of a honeycomb material. The upper surface of the rigid floor panel <NUM> may be protected by a protective floor cover preferably made of a non-textile material. For example, the floor cover may be attached to the floor panel using double sided tape. The rigid floor panel <NUM> is fixed to brackets <NUM> that may form part of the fuselage structure <NUM> or may be connected to the fuselage structure <NUM>.

As can be seen in <FIG>, the sidewalls <NUM> of the liner are spanned at a distance d from the enclosing outer fuselage structure <NUM> of the aircraft. Thus, the enclosing aircraft fuselage structure is protected from objects deflecting the sidewalls <NUM> of the bag <NUM>. For maximum protection, dampening pads <NUM> made of a foam, preferably of an expanded polypropylene, may be arranged between the sidewalls <NUM> of the liner and the enclosing outer fuselage structure <NUM> of the aircraft <NUM>.

As mentioned above, the cargo and/or accessory compartment <NUM> is accessible from the outside through a boot lid <NUM> of the aircraft <NUM>. To this end, the bag <NUM> of fire-resistant and gas tight flexible fabric must be provided with an opening in the area of the boot lid <NUM>. Said opening <NUM> of the bag <NUM> is shown in <FIG>. A gas tight closure may be guaranteed by a double sealing that is also shown in <FIG>. An outer fire-resistant sealing <NUM> is provided between a door structure <NUM> of the boot lid <NUM> and the fuselage structure <NUM>. An inner fire-resistant sealing <NUM> is provided between the door structure <NUM> of the boot lid <NUM> and the bag <NUM>. As shown in <FIG>, an edge of the bag <NUM> around the bag's opening is attached to and lying flat against the fuselage structure <NUM>. The door structure <NUM> of the boot lid <NUM> may be lined with the same fire-resistant and gas tight flexible fabric that the bag <NUM> is made of. This piece of door fabric is designated in <FIG> at <NUM>.

As shown in <FIG>, a rear loading edge of the rigid floor panel <NUM> may be protected by a scuff plate <NUM>. Preferably, the scuff plate <NUM> is made of a metal material.

The bag <NUM> may be provided with openings for a smoke detector or a continuous-loop system and/or a light and/or a floor frame fastener and/or a floor panel fastener. The openings are preferably sealed around cables and fasteners using jubilee clips or similar.

Furthermore, the cargo and/or accessory compartment <NUM> may either be sized for the resulting differential pressure or it may comprise a small valve to equalize the pressure while restricting the airflow so that a fire will consume more oxygen than what is potentially provided through the valve. The valves is installed to relief overpressure in the compartment during ascent. During descent, the compartment may be compressed without a differential pressure relief or a relief may be initiated by manual deployment of a separate relief valve. The valve(s) may be arranged in the bag or in the rigid floor panel.

<FIG> shows a second embodiment of the cargo and/or accessory compartment <NUM> that is not part of the invention. The second embodiment is very similar to the first embodiment shown in <FIG> and differs from the first embodiment in that the rigid floor panel <NUM> is pan-shaped and comprises a bottom plate <NUM> and a sidewall <NUM> protruding from the bottom plate <NUM>. This guarantees that the enclosing outer fuselage structure <NUM> of the aircraft <NUM> is protected in a floor area of the cargo and/or accessory compartment <NUM>, for example if heavy and/or sharp objects slide to the side or press against a sidewall <NUM> of the bag <NUM>. With this second embodiment, the dampening pads <NUM> of the first embodiment may be omitted. However, depending on the distance d and the height of the floor panel's sidewall <NUM>, it may still be advantageous to provide dampening pads for a better protection of the aircraft's fuselage.

<FIG> and <FIG> show a third embodiment of the cargo and/or accessory compartment <NUM> that is part of the invention. The third embodiment differs from the first and second embodiments shown in <FIG> in that the floor <NUM> is not formed by a rigid floor panel. Instead, the bag <NUM> is adapted to form the floor of the cargo and/or accessory compartment <NUM>. To this end, the liner further comprises a floor frame <NUM> spanning a floor portion <NUM> of the fabric. This embodiment offers a very lightweight construction since the floor of the cargo and/or accessory compartment <NUM> is mainly formed by the fire-resistant and gas-tight flexible fabric. The floor frame <NUM> is necessary in order to span and thereby stabilize the fabric. Similar to the rigid floor panel of the first and second embodiments, the floor frame <NUM> is attached to brackets <NUM> of the fuselage structure <NUM> of the aircraft <NUM>, for example via screw connections. The frame may be made of a carbon fiber reinforced polymer which adds to a lightweight construction.

The floor portion <NUM> of the fabric is a separate piece from a remainder of the bag <NUM> such that the floor portion <NUM> is replaceable independently from the remainder of the bag with or without the floor frame <NUM>. This facilitates maintenance and repair of the cargo and/or accessory compartment <NUM>. For example, the floor portion <NUM> may be detachable from the floor frame <NUM> eir the and the floor portion <NUM> of the fabric is detachable from the remainder of the bag <NUM>.

<FIG> shows a schematic perspective view of a cargo and/or accessory compartment <NUM> according to a fourth embodiment of the invention. The cargo and/or accessory compartment <NUM> is similar to the cargo and/or accessory compartments according to the first, second and third embodiments. It is also formed by a liner that comprises a bag <NUM> of fire resistant and gas tight flexible fabric. The bag <NUM> comprises a loading opening <NUM> through which luggage and/or other cargo items can be loaded into or unloaded from the cargo and/or accessory compartment <NUM>. <FIG> shows the loading opening <NUM> in a fully opened state. Portions of the bag <NUM> around the loading opening <NUM> are foldable along folding lines <NUM> such that the opening <NUM> may be closed by folding said portions together as shown in <FIG> which shows the opening <NUM> in an almost fully closed state.

The cargo and/or accessory compartment according to the first, second, third and fourth embodiments may easily be installed as follows:.

Claim 1:
A liner for a cargo and/or accessory compartment (<NUM>) of an aircraft (<NUM>), wherein the liner is fire-resistant and gas tight to the extent of fire starving capability and keeps smoke emissions to a neglectable level in terms of flight safety, wherein the liner comprises a bag (<NUM>) of fire-resistant and gas tight flexible fabric, wherein the bag (<NUM>) is adapted to form at least a ceiling (<NUM>) and sidewalls (<NUM>) of the cargo and/or accessory compartment (<NUM>), and wherein the bag (<NUM>) is adapted to form a floor (<NUM>) of the cargo and/or accessory compartment (<NUM>), wherein the liner further comprises a floor frame (<NUM>) for spanning a floor portion (<NUM>) of the fabric, characterized in that the floor portion (<NUM>) of the fabric is a separate piece from a remainder of the bag (<NUM>) such that the floor portion (<NUM>) is replaceable independently from the remainder of the bag (<NUM>) with or without the floor frame (<NUM>).