Aircraft Shell Module

1. Field of the Invention.

This invention relates to aircraft interior modules. More particularly, it refers to an aircraft interior made of molded honeycomb panels with a layer of damping material bonded within the panels and the panel mounted so as to avoid direct contact with the interior of the aircraft skin.

2. Description of the Prior Art.

Interior insulation systems for airplanes have been well known for a long period of time. Improvements on these systems such as shown in U.S. Pat. No. 3,740,905 have not emphasized sound absorbing properties. However, sound absorption is becoming more and more important because of advanced power systems for new aircraft.

The level of low frequency sound impinging on the fuselage of future propfan powered airplanes is predicted to be higher than the level of low frequency jet exhaust noise that impinged on the aft fuselage of turbojet powered 707 and DC8 airplanes. The level of structure borne noise from propfan power propagating as vibration through the structure of a fuselage may well exceed that experienced on existing turbofan powered airplanes such as 727's and DC9's with aft mounted engines.

In 1986, passengers in newly delivered medium to long range transport airplanes (and the airlines that operate those airplanes) were accustomed to the level of acoustical comfort typified by the noise levels in 737, 300 and MD 80 airplanes where the levels of engine noise and boundary layer noise were well below the level of noise from advanced propfan propulsion systems.

A major task of the manufacturers is to find a means to introduce the fuel efficiency of advanced propfan engines without degrading the level of acoustical comfort provided for the passengers and crew by current technology transports.

Many business jet airplanes have special requirements for low interior noise levels during cruise. The interiors of most business jet airplanes are not installed by the airplane manufacturer because of the great variety of custom designs which are offered for individual operators. Airplanes are delivered in a "green" condition to "completion centers" for installation of the interior. To achieve the desired low interior noise levels, the installer of the interior utilizes special techniques and various combinations of damping material, vibration absorbers, vibration isolators, massive septa, and sound absorbing material.

A conventional approach to achieve low cabin noise levels has been to install fiberglass blankets between the fuselage frames for high frequency noise reduction. Noise reduction at low frequencies is provided by a massive septum made from a sheet of loaded vinyl (lead vinyl) outboard of the interior trim panel.

Double wall concepts have been evaluated theoretically and experimentally for transport category airplanes and versions of the concept are incorporated in all passenger carrying aircraft. The skin of the airplane forms one of the two walls; the interior sidewall trim panels and the ceiling panels form the other wall. A unified approach to a double wall has not been developed for transport category airplanes.

We have invented a module for aircraft that is self supporting and can contain all necessary interior aircraft auxilliary equipment as well as acoustical panel components to substantially reduce engine noise to persons within the aircraft. Our module is capable of being built in a factory and then installed in sections within the "green" condition aircraft.

The module has two side panels which are each arcuate in shape and elongated deck panels. Each panel contains a layer of damping material between layers of a honeycomb material with a structural face forming the exterior of the panel. The first or upper end of each module side panel is mounted in multiple elastomeric isolators located in an overhead channel. The channel is held in place by an overhead mounting plate which in turn is held in place by multiple support brackets attached to the overhead of the fuselage interior.

The second or lower end of each module panel is mounted in multiple elastomeric isolators mounted in respective port or starboard channels. These channels are attached to multiple support brackets which are in turn attached to the respective port or starboard side of a fuselage deck or floor beam. The fuselage deck is covered with rectangular panels.

The entire module is spaced apart from the interior fuselage of the aircraft. Consequently, the panels are held rigidly but have no direct contact with structural noise transmitting elements of the aircraft.

The present invention may be best understood by those of ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which:

FIG. 1, is a cross-section view of an aircraft fuselage in which the one aisle module of this invention has been installed.

FIG. 2 is a cross-section view of an aircraft fuselage in which the two aisle module of this invention has been installed.

FIG. 3 is an exploded view of one section of the module.

FIG. 4 is a cross-section view of the acoustical sandwich in the aircraft deck.

FIG. 5 is a broken section view of a panel mounted in an isolator.

FIG. 6 is a front view of a first end of each panel joined together ad some suspended interior accessory equipment.

FIG. 7 is a front elevation view in section of the first end of each panel joined together.

FIG. 8 is a front elevation view in section of the second end of the starboard module panel mounted within the starboard isolators.

FIG. 9 is a front elevation view in section of the second end of the port module panel showing a through bolt mount.

FIG. 10 is a cross-section view of the panel layers.

Throughout the following detailed description similar reference numerals refer to similar elements in all figures of the drawings.

With reference to FIGS. 1 and 2, the module 10 is shown spaced apart from the aircraft skin 12. The aircraft has a deck panel 14 and under the deck panel is a storage area 16. The passenger space 18 contains seats 20, starboard luggage box 22 and port luggage box 24 and in FIG. 2, overhead luggage box 26. The module support beam 28 is located in the overhead area of the aircraft.

The module 10 is made up of a starboard panel 30 and a port panel 32. The starboard panel 30 has a first end 34 and a second end 36. See FIG. 3.

The first end 34 of starboard module panel 30 is mounted in multiple elastomeric starboard overhead isolators 38 which are frictionally inserted within channel 40. In like manner, the second end 36 of module panel 30 is mounted in starboard deck isolators 42 which are mounted in a starboard deck channel 44.

The overhead channel 40 is held in place by mounting bracket 50 and longitudinal close-out member 48. Bolt 49 and nut 51 hold the overhead assembly of 38, 40, 48, 50, 72 and 74 to support beam 28.

Channel 44 is held in place by starboard support brackets 46 mounted to the aircraft floorbeam 14. A trim panel 45 can be applied to the side of channel 44 facing the inside of the aircraft.

Each module panel is attached to its adjacent module panel by an overhead module joiner 52 and a starboard or port module joiner 54. An overlap clip 56 on the overhead joiner 52 and overlap clip 58 on the starboard joiner 54 are hooked to the window openings in the module. Overhead joiner 52 and joiner 54 retain foam seal 60 in place.

Seat track 86 supports structural deck panels 14. Acoustical deck panels 88 cover the deck panels 14. Groove 92 in the seat track 86 receives the seat 20 vertical support member 94. See FIGS. 1 and 4.

Accessory equipment such as overhead bin 22 is attached to a support fitting 62 which is fastened to honeycomb panel 30. Overhead bins such as 26 are supported by struts 64 attached to mounting bracket 50. A frameliner 66 encloses the overhead space 68 of the module. This overhead space 68 contains the additional auxiliary equipment such as air vents 70.

In like manner, the first end 76 of port module panel 32 is mounted in the overhead area of the aircraft in elastomeric isolators 72 contained within channel 74. The second end 77 is mounted in isolators 78 contained within channel 79. A through bolt 96 prevents forward movement of channel 44 or 79.

Each panel 30 or 32 contains a damping sheet of vinyl 80 separating honeycomb cores 82 on each side. Exterior to each honeycomb core 82 is a structural face 84. The panel is lightweight and suppresses transmission of sound while still maintaining structural integrity.

Each isolator consists of a cartilage of vibration absorbing material which is usually an elastomer but can be substituted with other resilient vibration absorbing materials. Each isolator is frictionally attached to the interior of a channel. Each support bracket 46 or 90 is provided with serrated edges 93 to adjust their position. Adjustment is made by loosening through bolt 96 so that the channel 44 or 79 can be moved up or down with respect to the bracket 46 or 90 respectively. The number of support brackets 46 or 90 is optional and is determined entirely by the structural requirements of the aircraft. Bolt assembly 91 attaches the bracket 46 or 90 to the aircraft deck 14. The configuration described rigidly supports the panels within the aircraft and is spaced apart from the fuselage skin so that a cocoon structure is created which can support all interior accessory equipment such as bins 22, 24 and 26 without sacrificing any acoustical dampening effect. The arcuate structure of the panels add additional support for these accessory items.

Minor modifications and equivalent elements can be substituted in the acoustical module without departing from the invention as described herein.