Angle-of-attack flight computer systems and methods
According to one implementation of the present disclosure, a method for determining angle-of-attack for an unpowered vehicle is disclosed. The method includes: determining a monotonic portion of a look-up curve of an angle-of-attack operating plot; during flight, determining, by an accelerometer disposed on the unpowered vehicle, first and second accelerometer outputs, where the first and second accelerometer outputs correspond to first and second body-fixed load factor measurements, respectively; determining an operating point on the monotonic portion by applying a quotient of the first and second accelerometer outputs to the angle-of-attack operating plot; and determining an angle-of-attack parameter corresponding to the determined operating point.
1. A method for determining an angle-of-attack for an unpowered vehicle, comprising:
determining a monotonic portion of a look-up curve of an angle-of-attack operating plot;
during flight, determining, by an accelerometer disposed on the unpowered vehicle, first and second accelerometer outputs, wherein the first and second accelerometer outputs correspond to first and second body-fixed load factors, respectively;
determining an operating point on the monotonic portion by applying a quotient of the first and second accelerometer outputs to the angle-of-attack operating plot; and
determining an angle-of-attack parameter corresponding to the determined operating point.
2. The method of claim 1 , further comprising, in response to determining the angle-of-attack parameter, at least one of:
generating, at least partially by a flight computer system, a flight profile of the unpowered vehicle; and
adjusting, at least partially by the flight computer system, an angle-of-attack setting of the unpowered vehicle based on the angle-of-attack parameter.
3. The method of claim 1 , wherein determining the operating point on the monotonic curve portion by applying the quotient of the first and second accelerometer outputs to the angle-of-attack operating plot comprises:
matching a quotient of the first and second accelerometer outputs to a substantially equivalent body-fixed acceleration, wherein the body-fixed acceleration corresponds to a particular quotient of a particular first and second body-fixed coefficients.
4. The method of claim 3 , wherein the particular quotient of the first and second body-fixed coefficient corresponds to a particular respective first and second aerodynamic data characteristic.
5. The method of claim 4 , wherein the particular respective first and second aerodynamic data characteristic corresponds to a particular respective lift coefficient metric and drag coefficient metric.
6. The method of claim 1 , wherein the monotonic curve portion corresponds to a plurality of body-fixed accelerations as a function of a plurality of angle-of-attack parameters.
7. The method of claim 6 , wherein the plurality of angle-of-attack parameters corresponds to a respective range of prospective angle-of-attack directions.
8. The method of claim 7 , wherein the angle-of-attack parameter of the plurality of angle-of-attack parameters corresponds to one direction of the range of the prospective angle-of-attack directions, and wherein the angle-of-attack parameter corresponds to a lift-to-drag-optimized angle-of-attack, a minimum-sink rate-optimized angle of attack, or a combination thereof.
9. The method of claim 6 , wherein the plurality of body-fixed accelerations corresponds to a quotient of the pluralities of first and second body-fixed coefficients.
10. The method of claim 9 , wherein the plurality of a first body-fixed coefficient is based on a corresponding plurality of a first aerodynamic data characteristic and a range of angle-of-attack directions.
11. The method of claim 10 , wherein the plurality of a first aerodynamic data characteristic comprises a plurality of lift coefficient metrics.
12. The method of claim 9 , wherein the plurality of a second body-fixed coefficient is based on a corresponding plurality of a second aerodynamic data characteristic and a range of angle-of-attack directions.
13. The method of claim 12 , wherein the plurality of a second aerodynamic data characteristic comprises a plurality of drag coefficient metrics.
14. The method of claim 1 , wherein the operating point corresponds to a particular body-fixed acceleration as function of a corresponding particular angle-of-attack parameter.
15. The method of claim 1 , wherein the first body-fixed load factor measurement corresponds to a quotient of a magnitude of axial force and weight, and wherein the second body-fixed load factor measurement corresponds to a quotient of a magnitude of normal force and weight.
16. The method of claim 1 , wherein determining the monotonic portion of the look-up curve of the angle-of-attack operating plot comprises:
obtaining pluralities of first and second aerodynamic data characteristics as respective functions of a range of angle-of-attack directions;
computing, by a processor, pluralities of first and second body-fixed coefficients as the respective functions of the range of angle-of-attack directions;
determining, by the processor, a plurality of body-fixed accelerations as a function of a prospective range of the range of angle-of-attack directions based on respective pluralities of quotients of the first and second body-fixed coefficients as the respective functions of the range of angle-of-attack directions, wherein the determined plurality of body-fixed accelerations as a function of a prospective range of the range of angle-of-attack directions corresponds to the look-up curve of the angle-of-attack operating plot; and
determining the monotonic portion based on a filtering, by the processor, of the look-up curve.
17. The method of claim 16 , wherein the pluralities of first and second aerodynamic data characteristics are obtained by estimating the range of the body-fixed accelerations for the vehicle or by measuring wind tunnel data with respect to the vehicle.
18. The method of claim 16 , wherein a graph comparing a range of body-fixed accelerations as a function of the prospective range of the range of angle-of-attack directions corresponds to the angle-of-attack operating plot.
19. A flight computer system comprising:
a processor; and
a memory accessible to the processor, the memory storing instructions that are executable by the processor to perform operations comprising:
determining a monotonic portion of a look-up curve of an angle-of-attack operating plot;
during flight, receiving from an accelerometer disposed on the unpowered vehicle, first and second accelerometer outputs, wherein the first and second accelerometer outputs correspond to first and second body-fixed load factor measurements, respectively;
determining an operating point on the monotonic portion by applying a quotient of the first and second accelerometer outputs to the angle-of-attack operating plot; and
determining an angle-of-attack parameter corresponding to the determined operating point.
20. A non-transitory computer-readable storage device storing instructions that, when executed by a processor, cause the processor to:
determine a monotonic portion of a look-up curve of an angle-of-attack operating plot;
during flight, receive from an accelerometer disposed on the unpowered vehicle, first and second accelerometer outputs, wherein the first and second accelerometer outputs correspond to first and second body-fixed load factor measurements, respectively;
determine an operating point on the monotonic portion by applying a quotient of the first and second accelerometer outputs to the angle-of-attack operating plot; and
determine an angle-of-attack parameter corresponding to the determined operating point.