Projectile Tail Fin and Canard Configuration for Roll Stabilization
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Solution Overview
Problem
Existing projectiles and missiles face challenges in efficiently controlling attitude and roll during both ballistic and gliding phases due to the need for continuous adjustments and complex control systems, particularly when using continuously rolling airframes and multiple canards that suffer from aerodynamic interference.
Innovation Solution
A projectile design featuring a rotationally symmetrical array of tail fins that reconfigures to an asymmetric array during the gliding phase, combined with canards that extend and retract differentially to generate lift and control roll, allowing for attitude stabilization and directional control without continuous rotation or complex actuation systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If continuously rolling airframes with multiple canards are used for attitude control, then directional control capability is improved, but device complexity and aerodynamic interference increase
Solution Approach 1:
The tail fins are configured to rotate from a first angular position during ballistic phase to a second angular position during gliding phase, transforming the stabilization mechanism from static to dynamic. This allows the same physical structure to serve different control functions at different flight stages, reducing the need for additional complex control surfaces while maintaining directional control capability
Solution Approach 2:
The tail fins are positioned asymmetrically relative to the projectile axis, creating inherent aerodynamic stability characteristics that eliminate the need for continuous active control during ballistic phase. This asymmetric configuration provides passive stabilization, reducing device complexity while maintaining control capability during gliding phase when active control is needed
2Ease of operation
If continuously rolling airframes with multiple canards are used for attitude control, then directional control capability is improved, but aerodynamic interference increases
Solution Approach 1:
The tail fins dynamically adjust their angular position between ballistic and gliding phases, optimizing aerodynamic performance for each phase. During ballistic phase, the fins are positioned to minimize drag and interference, while during gliding phase, they are repositioned to provide effective control authority, thereby reducing overall aerodynamic interference while maintaining control capability
Solution Approach 2:
The invention extracts the stabilization function from the control surfaces by using dedicated tail fins for passive ballistic stabilization, allowing the canards to focus solely on active gliding phase control. This separation of functions reduces aerodynamic interference between stabilization and control surfaces, as each operates independently in its optimized configuration
3Measurement precision
If complex control systems with continuous rotation are used, then attitude control precision is improved, but mechanical complexity increases
Solution Approach 1:
The control system uses discrete angular positions of the tail fins rather than continuous rotation, achieving sufficient attitude control precision through two distinct configurations. This discrete dynamic adjustment reduces mechanical complexity by eliminating the need for continuous rotation mechanisms while maintaining adequate control precision for both ballistic and gliding phases
Solution Approach 2:
The flight control function is segmented into two distinct phases with different control mechanisms: passive aerodynamic stabilization during ballistic phase and active canard control during gliding phase. This segmentation allows each phase to use the simplest appropriate control method, reducing overall mechanical complexity while maintaining precision where needed
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 design reduces the complexity and cost of roll-controlled airframes by using dihedral tail fins and variable canards to stabilize and control the projectile's attitude, minimizing aerodynamic interference and enabling precise navigation with reduced mechanical complexity.
Implementation Method 1
canards each of which is adapted to extend from and retract into the body so as to expose a variable surface area so that in use differential lift can be generated tending to bank the body
Implementation Method 2
a plurality of tail fins and at least a pair of incidence control means at a forward position of the body
Data Source
AI summary
A gun-fired projectile or ballistic missile (1) is equipped with a pair of canards (3) and an array of tail fins (2). Selected tail fins can be retracted or jettisoned following the ballistic phase to vary the geometry of the array from a rotationally symmetrical configuration to an asymmetric configuration for the glide phase, which together with the canards tends to stabilize the projectile in roll. The canards (3) can be independently extended and retracted with respect to the body of the projectile to generate differential lift for banking the projectile to turn. The canards (3) also preferably have a positive dihedral angle with respect to the intended gliding attitude. In an alternative embodiment the canards are replaced by functionally equivalent thrusters.