Adjustable size inlet system

• US 10,107,196 B2
• Filed: 08/08/2014
• Issued: 10/23/2018
• Est. Priority Date: 08/08/2014
• Status: Active Grant

• Current Assignee: Thomas International, Inc.
• Original Assignee: Thomas International, Inc.
• Inventors: Devine, Michael Thomas
• Primary Examiner(s): Rivera, Carlos A
• Assistant Examiner(s): Thomas, Kyle
• Application Number:
  US14/455,637
• Publication Number:
  US 20160040595A1
• Time in Patent Office: 1,537 Days
• CPC Class Codes: B64D 2033/0226 comprising boundary layer control means
• CPC Class Codes: B64D 2033/0253 specially adapted for particular type of aircraft
• CPC Class Codes: B64D 2033/0286 for turbofan engines
• CPC Class Codes: B64D 33/02 of combustion air intakes air intakes for gas-turbine plants or jet-propulsion plants per se F02C7/04; air intakes for combustion engines in general F02M35/00
• CPC Class Codes: F02C 3/107 with two or more rotors connected by power transmission
• CPC Class Codes: F02C 7/042 having variable geometry
• CPC Class Codes: F02K 3/06 with front fan
• CPC Class Codes: F02K 3/077 the plant being of the multiple flow type, i.e. having three or more flows

Abstract

An adjustable size inlet duct system for a ducted fan propulsion system may change its inlet profile to enhance thrust levels in low-speed and hovering flight conditions and may change its inlet profile to reduce drag to permit faster flight speeds at higher operating speeds. The adjustable size inlet duct system may include duct petals and associated actuators. During slow speed flight, the petals may expand to generate a rounded large inlet area bellmouth profile. At higher flight speeds, the petals may contract to reduce the profile drag of the duct in forward flight. An optional exterior bypass duct may be included to provide additional thrust in excess of the thrust provided by the ducted fan. An optional annular electric motor housed in the exterior bypass duct may be included to generate still more excess thrust.

Claims

1. An adjustable size inlet system for a fan duct containing a fan, the adjustable size inlet system comprising:

a plurality of nested structural tubes forming a ring;

a petal array comprising an interleaved plurality of petals arranged around a perimeter of the ring to define an adjustable size inlet lip, each petal comprising an upper portion curved over, and at least partially enclosing, at least a portion of the plurality of nested structural tubes; and

a plurality of mechanical actuators to cause the plurality of nested structural tubes to move radially outward and inward, thereby causing an increase or a decrease of a circumference of the adjustable size inlet lip, wherein;

the partially enclosed portions of the plurality of nested structural tubes cause corresponding upper portions of the plurality of petals to expand to form a bellmouth inlet profile when the plurality of mechanical actuators cause the circumference of the adjustable size inlet lip to increase; and

the corresponding upper portions of the plurality of petals contract to form a cylindrical inlet profile when the plurality of mechanical actuators cause the circumference of the adjustable size inlet lip to decrease.

2. The adjustable size inlet system of claim 1, wherein the plurality of nested structural tubes are operatively coupled in a sliding arrangement, wherein:

the plurality of nested structural tubes slide circumferentially outward to increase the circumference of the adjustable size inlet lip when the plurality of mechanical actuators move the plurality of nested structural tubes radially outward; and

the plurality of nested structural tubes slide circumferentially inward to decrease the circumference of the adjustable size inlet lip when the plurality of mechanical actuators move the plurality of nested structural tubes radially inward.

3. The adjustable size inlet system of claim 1, wherein each petal of the plurality of petals further comprises a lower portion affixed to the edge of the fan duct, wherein each lower portion:

forms a curved profile when the plurality of mechanical actuators moves the plurality of nested structural tubes radially outward; and

forms a linear profile when the plurality of mechanical actuators moves the plurality of nested structural tubes radially inward.

4. The adjustable size inlet system of claim 3, wherein each petal of the petal array comprises a strip, the strip comprising the upper portion and the lower portion at opposite ends of the strip.

5. The adjustable size inlet system of claim 1, further comprising a plurality of structural hub and tube units operatively connected to the plurality of mechanical actuators, each structural hub and tube unit enclosed within one of the plurality of nested structural tubes, wherein the plurality of mechanical actuators each cause a corresponding structural hub and tube unit to move radially inward and outward to cause the plurality of nested structural tubes to move radially inward and outward, thereby contracting or expanding the circumference of the adjustable size inlet lip.

6. The adjustable size inlet system of claim 5, wherein at least a second portion of the plurality of nested structural tubes slide circumferentially apart or together when the plurality of mechanical actuators cause the structural hub and tube units to move radially inward and outward to cause the plurality of nested structural tubes to move radially inward and outward.

7. The adjustable size inlet system of claim 1, wherein each mechanical actuator of the plurality of mechanical actuators are located in equipment bays and comprise a piston arm attached to an actuator arm at an actuator pivot between an opposed first end and second end of the actuator arm, wherein:

the first end of each actuator arm is operatively coupled to an end pivot entrained within a curved slot formed within a duct structural wall within the adjustable size inlet system; and

the second end of each actuator arm is attached to one of a plurality of structural hub and tube units within one of the plurality of nested structural tubes.

8. The adjustable size inlet system of claim 7, wherein:

the second end of each actuator arm causes the attached structural hub and tube unit to move radially outward and causes the end pivot to slide to a lower end of the curved slot when the piston arm is retracted;

the second end of each actuator arm causes the attached structural hub and tube unit to move radially inward and causes the end pivot to slide to an upper end of the curved slot when the piston arm is extended.

9. The adjustable size inlet system of claim 8, wherein at least a second portion of the plurality of nested structural tubes slide circumferentially apart or together when the actuator arms cause the corresponding attached structural hub and tube units to move radially outward or inward, thereby expanding or contracting the circumference of the adjustable size inlet lip.

10. The adjustable size inlet system of claim 1, wherein the plurality of nested structural tubes comprises:

a plurality of outer structural tubes;

a plurality of inner structural tubes, each inner structural tube comprising opposed inner tube ends inserted within corresponding adjacent outer structural tubes; and

a plurality of structural hub and tube units, each structural hub and tube unit comprising a solid cylinder affixed within a structural hub tube, each structural hub tube comprising opposed hub tube ends inserted within corresponding adjacent inner structural tubes.

11. The adjustable size inlet system of claim 10, wherein the plurality of nested structural tubes further comprises a plurality of alignment pins, each end of each alignment pin affixed to one of a pair of pin fixation fittings formed within the upper portion of an outer petal from the plurality of petals, each outer petal comprising two pairs of pin fixation fittings, and each alignment pin extending through a plurality of slots formed within corresponding adjacent petals, adjacent outer structural tubes, adjacent inner structural tubes, and adjacent structural hub and tube units, wherein a range of the expansion and contraction of the circumference of the adjustable size inlet lip is limited by a mechanical interference between each alignment pin and at least one end of at least one corresponding slot.

12. The adjustable size inlet system of claim 1, further comprising a plurality of control rods arranged around a perimeter of the adjustable size inlet system to limit the expansion and contraction of the circumference of the adjustable size inlet lip.

13. The adjustable size inlet system of claim 1, further comprising a plurality of sliding doors comprising a plurality of exterior bypass duct doors and a plurality of equipment bay doors arranged in an alternating sequence around an outer perimeter of a nacelle containing the fan duct and adjacent to the plurality of interleaved petals, the plurality of sliding doors sliding to maintain a position adjacent to the plurality of interleaved petals throughout the expansion and contraction of the plurality of petals.

14. The adjustable size inlet system of claim 13, further comprising a plurality of sidewall extenders within the nacelle, each sidewall extender shortening and elongating to adjust a length of a sidewall within the nacelle formed by each sidewall extender, thereby accommodating the expansion and contraction of the plurality of interleaved petals.

15. The adjustable size inlet system of claim 14, wherein each exterior bypass duct door further comprises a pair of projecting ridges, the pair of projecting ridges projecting laterally from opposed lateral edges of the exterior bypass duct door along at least a portion of the lateral edge, wherein each projecting ridge slideably engages with a corresponding engagement groove formed within an adjacent sidewall extender forming at least a portion of an outer surface of the nacelle, thereby providing support of the lateral edges of the exterior bypass duct door throughout a range of sliding.

16. The adjustable size inlet system of claim 13, further comprising:

a plurality of exterior bypass ducts, each exterior bypass duct extending within the nacelle between an upper exterior bypass duct inlet and a lower duct area operable outlet louver, wherein both the upper exterior bypass duct inlet and the lower duct area operable outlet louver oven through an outer surface of the nacelle that is radially outside of the fan duct;

each exterior bypass duct door of the plurality of exterior bypass duct doors seal the upper exterior bypass duct inlet when the exterior bypass duct door is raised and to open the upper exterior bypass duct inlet when the exterior bypass duct door is lowered; and

a plurality of sliding door operating assemblies, each sliding door operating assembly to raise and lower one of the exterior bypass duct doors.

17. The adjustable size inlet system of claim 16, further comprising a plurality of equipment bays, each equipment bay comprising an upper equipment bay formed within the nacelle and sealed at one end by one of the plurality of equipment bay doors;

wherein;

the one equipment bay door is raised and lowered by one of the plurality of sliding door operating assemblies;

the one equipment bay door is lowered to prevent mechanical interference with the petal array when the circumference of the adjustable size inlet lip is increased;

the one equipment bay door is raised to maintain a seal at the one end of the equipment bay when the circumference of the adjustable size inlet lip is decreased; and

the one equipment bay door further comprises an embedded linear guidebar guided by an extension track affixed over the one end of the equipment bay.

18. The adjustable size inlet system of claim 13, wherein the nacelle and adjustable size inlet system rotate to a horizontal orientation, a vertical orientation, clockwise relative to the horizontal orientation, counterclockwise relative to the horizontal orientation, clockwise relative to the vertical orientation, counterclockwise relative to the vertical orientation, and to a plurality of intermediate orientations between the horizontal orientation and the vertical orientation.

19. The adjustable size inlet system of claim 1, wherein each petal of the plurality of petal slides circumferentially apart or together from each corresponding petal when the mechanical actuators expand or contract the circumference of the adjustable size inlet lip.

20. The adjustable size inlet system of claim 1, wherein each mechanical actuator of plurality of mechanical actuators, located in bypass duct bays, comprises an actuator arm and a piston arm attached to the actuator arm at an actuator pivot between an opposed first and second end of the actuator arm, wherein:

the first end of each actuator arm is operatively coupled to an end pivot entrained in within a curved slot formed within a duct structural wall within the adjustable size inlet system; and

the second end of each actuator arm is attached to one of a plurality of structural hub and tube units within one of the plurality of nested structural tubes.

21. The adjustable size inlet of claim 20, wherein each actuator arm of the plurality of actuator arms located in bypass duct bays, wherein:

the second end of each actuator arm causes the attached structural hub and tube unit to move radially outward and causes the end pivot to slide to the lower end of the curved slot when the piston arm in the equipment bay is retracted; and

the second end of each second actuator arm causes the attached structural hub and tube unit to move radially inward and causes the end pivot to slide to an upper end of the curved slot when the piston arm in the equipment bay is extended.

22. An adjustable size inlet system for attachment to an edge of a fan duct, the adjustable size inlet system comprising:

a plurality of nested structural tubes operatively coupled in a sliding arrangement and forming a ring;

a petal array comprising a plurality of outer petals interleaved with a plurality of inner petals, the petal array arranged around a perimeter of the ring to define an adjustable size inlet lip, each petal of the petal array comprising a strip with an upper portion and a lower portion at opposite ends of the strip, wherein;

each upper portion is curved over at least a portion of the plurality of nested structural tubes to at least partially enclose the portion of the plurality of nested structural tubes; and

each lower portion is attached to the edge of the fan duct;

a plurality of mechanical actuators located in a plurality of equipment bays, each mechanical actuator comprising a piston arm attached to an actuator arm at an actuator pivot between an opposed first end and second end of the actuator arm, wherein the first end of each actuator arm is operatively coupled to an end pivot entrained within a curved slot formed within a duct structural wall within the adjustable size inlet system; and

structural hub and tube units operatively connected to the plurality of mechanical actuators, each structural hub and tube unit enclosed within one of the plurality of nested structural tubes and attached to the second end of each actuator arm, wherein;

the second end of each actuator arm moves each corresponding attached structural hub and tube Unit radially outward when the piston arm is retracted;

the second end of each actuator arm moves each corresponding attached structural hub and tube Unit radially inward when the piston arm is extended;

at least a second portion of the plurality of nested structural tubes slide circumferentially apart or together when the plurality of mechanical actuators move the plurality of structural hub and tube units outward or inward, thereby expanding or contracting a circumference of the adjustable size inlet lip;

each upper portion of each petal slides circumferentially apart or together from each corresponding adjacent upper portion of each adjacent petal when the plurality of mechanical actuators expand or contract the circumference of the adjustable size inlet lip;

each lower portion of each petal forms a curved profile when the plurality of mechanical actuators expand the circumference of the adjustable size inlet lip; and

each lower portion of each petal forms an linear profile when the plurality of mechanical actuators contract the circumference of the adjustable size inlet lip.

23. The adjustable size inlet system of claim 22, wherein an exposed surface of the petal array defines an adjustable size inlet duct, wherein the exposed surface comprises a total of all exposed surfaces of the plurality of petals in the petal array.

24. The adjustable size inlet system of claim 22, wherein:

the adjustable size inlet system assumes bellmouth inlet profile when the plurality of mechanical actuators expand the circumference of the adjustable size inlet lip; and

the adjustable size inlet system assumes a cylindrical inlet profile when the plurality of mechanical actuators contract the circumference of the adjustable size inlet lip.

25. The adjustable size inlet system of claim 22, further comprising a plurality of perimeter control actuators, each perimeter control actuator comprising:

a control rod joining box affixed to one actuator arm of the plurality of actuator arms between the first end and second end of the one actuator arm, wherein the control rod joining box comprises;

a pair of gear systems at opposite ends of the control rod joining box, each gear system comprising a threaded fitting;

a motor operatively coupled to the pair of gear systems to reversibly rotate both threaded fittings of both gear systems when the motor is activated; and

a first control rod and a second control rod, each control rod comprising a first threaded portion at a first rod end and a second threaded portion at a second rod end opposite the first rod end;

wherein

each first rod end is operatively coupled to one threaded fitting of the control rod joining box by meshing the first threaded portion with the threaded fitting; and

each second rod end is operatively coupled to one adjacent threaded fitting of one adjacent control rod joining box;

wherein;

each control rod joining box is coupled to a first adjacent control rod joining box by the first control rod and to a second adjacent control rod joining box by the second control rod opposite to the first adjacent control rod joining box, forming a portion of a second continuous ring around the perimeter of the adjustable size inlet system;

each first threaded portion and each second threaded portion of each control rod translates in or out of each corresponding control rod joining box when each corresponding threaded fitting is rotated by each corresponding motor, causing the perimeter of the second continuous ring to decrease or increase; and

the operation of each motor is coordinated with the operation of the plurality of actuators to coordinate the decrease or increase of the circumference of the second continuous ring with the decrease or increase of the circumference of the adjustable size inlet lip.

26. The adjustable size inlet system of claim 22, wherein the plurality of nested structural tubes comprises:

a plurality of outer structural tubes evenly spaced around the circumference of the adjustable size inlet lip, each outer structural tube comprising a first curved tube enclosing an outer lumen extending a length of the outer structural tube and opening at each opposed end of the outer structural tube;

a plurality of inner structural tubes evenly spaced around the circumference of the adjustable size inlet lip, each inner structural tube comprising a second curved tube enclosing an inner lumen extending a length of the inner structural tube and opening at each opposed end of the inner structural tube, wherein each opposed end, and at least a portion of the inner structural tube, are situated within the outer lumen of an adjacent outer structural tube; and

the plurality of structural hub tube units evenly spaced around the circumference of the adjustable size inlet lip, each structural hub tube unit comprising a solid cylinder affixed within a third curved tube, wherein each opposed end of the third curved tube and at least a portion of the structural hub tube unit are situated within the inner lumen of an adjacent inner structural tube;

wherein;

each end of each inner structural tube slides in and out of a toroidal space between the outer structural tube and the structural hub and tube unit when the plurality of mechanical actuators move the plurality of structural hub and tube units radially inward and outward.

27. The adjustable size inlet system of claim 26, further comprising a plurality of alignment pins, each alignment pin affixed at each end to an opposed pair of pin fixation fittings situated near a lateral edge of each outer petal of the petal array, wherein:

a central portion of each pin extends inward through a pair of opposed petal slots formed within an underlying petal edge of an underlying inner petal of the petal array, wherein each petal slot extends along a portion of a width of the inner petal from a distal petal slot end near the underlying edge to a proximal petal slot end;

the central portion of each pin further extends inward through a pair of opposed outer slots formed within an underlying outer tube end of an underlying outer structural tube, wherein each outer slot extends along a portion of a length of the underlying outer structural tube from a distal outer slot end near the underlying outer tube end to a proximal outer slot end;

the central portion of each pin extends inward through a pair of opposed inner slots formed within an underlying inner tube end of an underlying inner structural tube, wherein each inner slot extends along a portion of a length of the underlying inner structural tube from a distal inner slot end near the underlying inner tube end to a proximal inner slot end; and

the central portion of the pin further extends through a hub slot formed within an underlying hub tube end of the structural hub and tube unit, each hub slot extending from a distal hub slot end near the underlying hub tube end for a portion of the length of the structural hub and tube unit to a proximal hub slot end.

28. The adjustable size inlet system of claim 27, wherein a range of sliding movement of the plurality of structural tubes is limited by a mechanical interference of each alignment pin with at least one or more corresponding slot ends selected from:

the proximal petal slot end, the proximal outer slot end, the proximal inner slot end, the proximal hub slot ends, the distal petal slot end, the distal outer slot end, the distal inner slot end, and the distal hub slot end.

29. The adjustable size inlet system of claim 22, wherein the plurality of petals comprises a plurality of first petals interleaved between a plurality of second petals, wherein:

each first petal comprises a first left lateral edge, a first right lateral edge, and a transition slit extending inward from the first left lateral edge to a centerline situated midway between the first left and first right lateral edges;

each second petal comprises a second left lateral edge and a second right lateral edge; and

each second right lateral edge is inserted into an adjacent transition strip of an adjacent first petal, wherein;

an upper portion of the second right lateral edge is situated between the underlying adjustable size inlet lip and a overlying upper portion of the adjacent first petal;

a lower portion of the second right lateral edge is situated over the lower portion of the adjacent first petal;

the second left lateral edge is situated between the underlying adjustable size inlet lip and an opposite adjacent first petal situated opposite to the adjacent first petal; and

each second right lateral edge slides in and out of each transition slit when the plurality of mechanical actuators contract and expand the circumference of the adjustable size inlet lip.

30. A ducted fan propulsion system comprising:

a main fan duct and an adjustable size inlet attached at an end of the main fan duct, the adjustable size inlet comprising;

a plurality of nested structural tubes operatively coupled in a sliding arrangement and forming a ring; and

a petal array comprising an interleaved plurality of petals arranged around a perimeter of the ring to define an adjustable size inlet system, each petal comprising;

an upper portion curved over, and at least partially enclosing, a first portion of the plurality of nested structural tubes; and

a lower portion attached to the main fan duct; and

a plurality of mechanical actuators to cause the plurality of nested structural tubes to move radially outward and inward, thereby causing an increase or a decrease of a circumference of the adjustable size inlet lip.

31. The ducted fan propulsion system of claim 30, further comprising a plurality of structural hub and tube units operatively connected to the plurality of mechanical actuators, each structural hub and tube unit enclosed within one of the plurality of nested structural tubes, wherein the plurality of mechanical actuators each cause a corresponding structural hub and tube unit to move radially inward and outward to cause the plurality of nested structural tubes to move radially inward and outward, thereby contracting or expanding the circumference of the adjustable size inlet lip.

32. The ducted fan propulsion system of claim 31, wherein each mechanical actuator of the plurality of mechanical actuators is located in an equipment bay and comprises a piston arm attached to an actuator arm at an actuator pivot between an opposed first end and second end of the actuator arm, wherein:

the first end of each actuator arm is operatively coupled to an end pivot entrained within a curved slot formed within a duct structural wall within the adjustable size inlet system;

the second end of each actuator arm is attached to one of the plurality of structural hub and tube units within one of the plurality of nested structural tubes;

the second end of each actuator arm and corresponding attached structural hub and tube unit move radially outward when the piston arm is retracted, thereby increasing the circumference of the adjustable size inlet lip;

the second end of each actuator arm and corresponding attached structural hub and tube unit move radially inward when the piston arm is extended, thereby decreasing the circumference of the adjustable size inlet lip;

at least a second portion of the plurality of nested structural tubes slide circumferentially apart or together when the plurality of mechanical actuators expand or contract the circumference of the adjustable size inlet lip;

each upper portion of the plurality of petals slides circumferentially apart or together from each corresponding adjacent upper portion when the plurality of mechanical actuators expand or contract the circumference of the adjustable size inlet lip;

each lower portion of the plurality of petals forms a curved profile when the plurality of mechanical actuators expand the circumference of the adjustable size inlet lip; and

each lower portion forms a linear profile when the plurality of mechanical actuators contract the circumference of the adjustable size inlet lip.

33. The ducted fan propulsion system of claim 31, wherein each mechanical actuator is located in a bypass duct bay and comprises an actuator arm coupled at an actuator pivot between an opposed first end and second end of the actuator arm, wherein:

the first end of each actuator arm is operatively coupled to an end pivot entrained within a curved slot formed within a duct structural wall within the adjustable size inlet system;

the second end of each actuator arm is attached to one of the plurality of structural hub and tube units within one of the plurality of nested structural tubes;

the second end of each actuator arm and corresponding attached structural hub and tube unit move radially outward when the piston arm is retracted, thereby increasing the circumference of the adjustable size inlet lip;

the second end of each actuator arm and corresponding attached structural hub and tube unit move radially inward when the piston arm is extended, thereby decreasing the circumference of the adjustable size inlet lip;

at least a second portion of the plurality of nested structural tubes slide circumferentially apart or together when the plurality of mechanical actuators expand or contract the circumference of the adjustable size inlet lip;

each upper portion of the plurality of petals slides circumferentially apart or together from each corresponding adjacent upper portion when the plurality of mechanical actuators expand or contract the circumference of the adjustable size inlet lip;

each lower portion of the plurality of petals forms a curved profile when the plurality of mechanical actuators expand the circumference of the adjustable size inlet lip; and

each lower portion forms a linear profile when the plurality of mechanical actuators contract the circumference of the adjustable size inlet lip.

34. A nacelle comprising:

a ducted fan wall enclosing a ducted fan and separating the ducted fan from a plurality of exterior bypass ducts

each exterior bypass duct extending within the nacelle between an upper exterior bypass duct inlet, and a lower duct area operable outlet louver, wherein both the upper exterior bypass duct inlet and the lower duct area operable outlet louver open through an outer surface of the nacelle that is radially outside of the ducted fan wall;

a plurality of exterior bypass duct doors, each exterior bypass duct door of the plurality of exterior bypass duct doors seal the upper exterior bypass duct inlet when the exterior bypass duct door is raised and to open the upper exterior bypass duct inlet when the exterior bypass duct door is lowered;

a plurality of sliding door operating assemblies, each sliding door operating assembly to raise and lower one of the exterior bypass duct doors.

35. The nacelle of claim 34, wherein each bypass duct comprises an upper exterior bypass duct and a lower exterior bypass duct and each upper exterior bypass duct further comprises:

a duct wall fixed section adjacent the upper area of the bypass duct and extending toward a first end of an actuator arm of an adjustable size inlet system;

a duct wall moveable section comprising a duct wall section mounted on the actuator arm; and

a pair of duct sidewall extenders, each duct sidewall extender comprising a fixed duct wall core extending outward from the duct wall fixed section and an inner extendable duct wall ply and an outer extendable duct wall ply on opposite sides of the fixed duct wall core, wherein the inner and outer extendable duct wall plies are fastened and may be raised or lowered together when the actuator arm moves radially inward or outward;

wherein;

the duct wall fixed section and the duct wall moveable section form a back wall of the upper exterior bypass duct; and

the fixed duct wall cores and inner extendable duct wall ply form a pair of lateral duct walls extending outward from the back wall of the upper exterior bypass duct.

36. The nacelle of claim 35, wherein the outer extendable duct wall plies are raised and lowered by a sidewall extender operating assembly comprising:

a sidewall extender motor operatively coupled to a lower pulley wheel, the lower pulley wheel coupled to an upper pulley wheel with a belt;

an axle operatively coupled to the upper pulley wheel, the axle comprising a gear-toothed rim; and

a gear strip affixed to a lateral surface of the inner extendable duct wall ply, wherein the gear strip is operatively coupled to the gear-toothed rim;

wherein the sidewall motor is activated to rotate the gear-toothed rim, causing the raising or lowering of the inner extendable duct wall ply and the fastened outer extendable duct wall ply.

37. The nacelle of claim 35, further comprising a flexible seal attached at an upper seal edge to the duct wall moveable section and attached at a lower seal edge to the duct wall fixed section.

38. The nacelle of claim 34, wherein each sliding door operating assembly comprises:

a door motor supported within a nacelle compartment;

a first lower door pulley operatively coupled to the door motor and a first upper door pulley operatively coupled to the first lower door pulley by a first belt;

a first drive wheel comprising first gear teeth operatively coupled to the first upper door pulley; and

a first door gearbar attached to an interior surface of the exterior bypass duct and operatively coupled to the first gear teeth of the first drive wheel, wherein the door motor rotates the first drive wheel to translate the first door gearbar, thereby raising or lowering the attached exterior bypass duct door.

39. The nacelle of claim 38, wherein each sliding door operating assembly further raises and lowers an equipment bay door, the sliding door operating assembly further comprising:

a second lower door pulley operatively coupled to the door motor by a control gear box and axle;

a second upper door pulley operatively coupled to the second lower door pulley by a second belt;

a second drive wheel comprising second gear teeth operatively coupled to the second upper door pulley; and

a second door gearbar attached to an interior surface of the equipment bay door and operatively coupled to the second gear teeth of the second drive wheel, wherein the door motor rotates the second drive wheel to translate the second door gearbar, thereby raising or lowering the attached equipment bay door.

40. The nacelle of claim 34, wherein each exterior bypass duct further comprises a rounded nose attached at a pivot affixed to an interior edge of a nacelle perimeter compartment, wherein:

the rounded nose is positioned over the edge of the nacelle perimeter compartment when the exterior bypass duct door is lowered to provide a smooth inlet edge for the open exterior bypass duct; and

the nose pivots upward to provide clearance when the exterior bypass duct door is raised.

41. A nacelle comprising:

a fan duct extending between a duct inlet and a duct exit;

a plurality of interleaved petals arranged around a perimeter of the duct inlet;

a plurality of mechanical actuators to cause the plurality of interleaved petals to expand to form a bellmouth inlet profile and to contract to form a cylindrical inlet profile;

a plurality of control rods arranged around a perimeter of the fan duct to limit expansion of the plurality of interleaved petals; and

a plurality of sliding doors arranged around an outer perimeter of the nacelle adjacent to the plurality of interleaved petals, the plurality of sliding doors sliding to remain adjacent to the plurality of interleaved petals throughout the expansion and contraction of the plurality of interleaved petals.

42. The nacelle of claim 41 further comprising a plurality of sidewall extenders within the nacelle to shorten and elongate, each sidewall extender shortening and elongating to adjust a length of a sidewall within the nacelle formed by each sidewall extender, thereby accommodating the expansion and contraction of the plurality of interleaved petals.