Flyable folding fin

A fin erector apparatus for extending a movable fin assembly from a stored position to a deployed position on a vehicle housing, said apparatus comprising:

• a controlled movable surface in said movable fin assembly;
• first hinge means in said movable fin assembly, having a first axis of rotation, for pivotally attaching said controlled movable surface to said movable fin assembly;
• second hinge means in said vehicle housing, having a second axis of rotation, for pivotally attaching said movable fin assembly to said vehicle housing;
• sensor means for creating a deployment position signal in response to the position of said movable fin assembly;
• control processor means for generating a control output signal in response to said deployment position signal;
• and
• drive motor means for applying a force to said controlled movable surface in response to said control output signal.

A method for erecting a folding fin from a storage position to a deployed position on an air flight vehicle housing having a fluid flow along said vehicle housing, said folding fin having a control angle position about a first axis of rotation and an erection angle position about a second axis of rotation, comprising the steps of:

• initiating fin deployment to expose the surface of said folding fin to said fluid flow;
• and
• performing repeatedly, until said folding fin is in said deployed position, the steps of
• computing the time rate of change of said erection angle position,
• computing an erection angle velocity error by subtracting said erection angle time rate of change from a predetermined angular velocity,
• computing a control angle correction to said control angle position for reducing said erection angle velocity error to zero, and
• rotating said movable hinge line about said first axis of rotation by said control angle correction.

A method for erecting a folding fin assembly from a storage position to a deployed position on a flight vehicle housing having a fluid flow along said vehicle housing, said folding fin assembly having a controlled movable surface having a control angle position about a first axis of rotation and an erection angle position about a second axis of rotation, comprising the steps of:

• initiating fin deployment to expose the surface of said folding fin assembly to said fluid flow;
• and
• performing repeatedly, until such folding fin assembly is in said deployed position, the steps of
• computing the time rate of change of said erection angle position,
• computing an erection angle velocity error by subtracting said erection angle position time rate of change from a predetermined angular velocity,
• computing a control angle correction to said control angle position for reducing said erection angle velocity error to zero, and
• rotating said controlled movable surface about said first axis of rotation by said control angle correction.