Rectangular Nacelles with Rotatable Flaps for Thrust Vectoring
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Solution Overview
Problem
Conventional aircraft propulsion systems with large round nacelles face issues such as increased drag, installation constraints, and susceptibility to bird ingestion, as well as yawing moments when one engine fails, which offset the advantages of larger nacelles and require additional tail surfaces.
Innovation Solution
The use of airfoil-shaped, rectangular nacelles mounted above the wings with rotatable air flow control surfaces at intake and exhaust ends, featuring horizontally extending electric motors and fans, and a rear boundary layer nacelle with rotatable yaw vanes, which reduces air turbulence and provides enhanced thrust, thrust vectoring, and thrust reversing capabilities while minimizing interference with the wing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If large round nacelles are used to increase engine size and thrust, then propulsive power is improved, but drag increases and ground clearance requirements increase
Solution Approach 1:
The single large round nacelle is segmented into multiple smaller rectangular nacelles (typically four) arranged in a square configuration. Each smaller nacelle contains its own engine and produces less individual drag, while the combined thrust of all four provides the necessary total propulsive power. The rectangular shape of each nacelle is more aerodynamically efficient than a round shape.
Solution Approach 2:
The nacelles are arranged in a two-dimensional square pattern on the wing surface rather than using a single large three-dimensional round nacelle hanging below the wing. This dimensional change allows better utilization of wing surface area, improves ground clearance (since the wing can be positioned lower), and reduces the vertical distance from the ground to the nacelle centers.
2Power
If large round nacelles are used to increase engine size, then propulsive power is improved, but installation space on the wing is reduced
Solution Approach 1:
The single large nacelle occupying a large vertical space below the wing is segmented into four smaller rectangular nacelles that lie flat on the wing surface. This segmentation allows the wing surface area to be more efficiently utilized, as the smaller rectangular nacelles occupy less vertical space and can be arranged in a compact square pattern.
Solution Approach 2:
The nacelles transition from a vertical arrangement (hanging below the wing) to a horizontal arrangement (lying on the wing surface). This dimensional change from vertical to horizontal placement maximizes the use of available wing surface area while minimizing interference with the wing's aerodynamic performance and high-lift device installation.
3Power
If large round nacelles are used, then engine size is increased, but yawing moment increases when one engine fails
Solution Approach 1:
The symmetric square arrangement of four engines provides inherent balance. When one engine fails, the remaining three engines are positioned asymmetrically relative to the aircraft centerline, but their combined thrust vector can be controlled to counteract the yawing moment more effectively than a single large engine. The distributed configuration reduces the leverage arm for yawing moments compared to a single large nacelle positioned far from the centerline.
4Power
If large circular inlet is used, then engine size is increased, but bird ingestion risk increases
Solution Approach 1:
The single large circular inlet is segmented into four smaller rectangular inlets, one for each nacelle. Smaller inlet openings present less target area for birds and reduce the likelihood of bird ingestion. The distributed arrangement of four smaller inlets across the wing surface also spreads the risk, so that if one inlet ingests a bird, the other engines remain unaffected.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces air turbulence, enhances propulsive thrust, and eliminates the need for a large vertical tail, improving aircraft performance and safety by allowing for efficient thrust management and reduced risk of passenger cabin damage from rotor bursts.
Implementation Method 1
upper and lower air inlet slats at the air intake end of the nacelle are rotatable downwardly relative to the air flow duct to increase lift of the aircraft during takeoff. Upper and lower air exhaust flaps at the air exhaust end of the nacelle are rotatable upwardly or downwardly relative to the air flow duct to either slow the speed of the aircraft while landing or increase lift during takeoff
Implementation Method 2
a plurality of electric motors and motor driven fans extending horizontally between the air intake and exhaust ends
Implementation Method 3
motor driven fans extending horizontally between the air intake and exhaust ends... to provide the aircraft with enhanced horizontal propulsive thrust, thrust vectoring and thrust reversing
Implementation Method 4
rotatable yaw vanes located behind the fans and the motors. The rear nacelle and the pair of turbo generators are preferably located behind both the pressure bulkhead and the pressurized passenger cabin of the aircraft to avoid damage to the passenger cabin in the event of a rotor burst
Data Source
AI summary
An aircraft having a fuselage with a nose and a flat tail at opposite ends and a pair of wings extending therefrom. A pair of nacelles are detachably connected to the top of respective ones of the wings to be spaced from the fuselage to establish an air flow space therebetween. Each wing-mounted nacelle includes a plurality of fans, a corresponding plurality of electric motors to drive the fans, and dividers that separate the fans from one another. Each wing-mounted nacelle also includes a pair of rotatable air inlet slats at an air intake end and a pair of rotatable air exhaust flaps at an air exhaust end that are rotated relative to one another to control horizontal propulsive thrust, thrust vectoring and thrust reversing of the aircraft. A third nacelle is mounted on top of the flat tail of the fuselage between a pair of horizontal turbo generators.