Rice Eclipse Rocketry · Avionics-Mechanical subteam · Aug 2025 to present
A set of canards near the nose of the rocket, each driven by its own servo, that deflect in flight to correct pitch and roll. The flight computer decides the angles. I designed the mechanism that turns servo torque into fin motion and holds everything aligned under flight loads.
[placeholder: turnable 3D CAD] file: assets/afs/canard-mechanism.glb In Onshape: right-click the assembly tab, Export, format glTF, binary (.glb). Keep it under 20 MB. An exploded configuration as a second file (canard-mechanism-exploded.glb) would be a nice bonus.
Canard actuation mechanism. Drag to rotate, scroll to zoom.
[placeholder: video] file: assets/afs/fins-moving.mp4 What to capture: the servos sweeping the canards through full travel on the bench, close enough to see the torque path from servo to shaft to fin. 15 to 30 seconds, steady phone, good light.
Fins actuating on the bench.
How it works
The flight computer reads the IMU and commands a deflection angle for each canard.
Each canard has its own servo. [add: number of canards, servo model, and torque]
The servo drives the canard shaft through [add: direct drive, linkage, or gear]. The housing carries the reaction loads into the airframe.
The whole assembly packages inside the airframe diameter next to the avionics stack. [add: airframe diameter]
Design loads
Design point: flight at about Mach 0.8.
Aerodynamic load on a deflected canard, carried through the shaft and into the housing.
Motor vibration. The structure's modes had to stay clear of the forcing frequencies.
Validation
Modal analysis in ANSYS Mechanical to keep the first structural modes clear of the motor's vibration spectrum. [add: first mode frequency vs the forcing frequency]
Aerodynamic loading in ANSYS Fluent at the Mach 0.8 condition. [add: peak load on a canard at max deflection]
Simulated flight disturbances: the canard system reduced RMS attitude error by 65%. [add: what disturbance was injected and which controller ran]
[placeholder: modal result] file: assets/afs/modal-result.png Mode shape with the frequency callout visible.
First mode of the mechanism housing.
[placeholder: Fluent result] file: assets/afs/fluent-result.png Pressure or velocity contour at the Mach 0.8 condition with the canard deflected.
Fluent result at Mach 0.8.
Status
[add: bench-tested, flown, or awaiting flight].
What went wrong, and what comes next
What went wrong
The 65% number is a simulation number. It comes from injected disturbances in a model, not from a flight. Until the system flies on an instrumented vehicle, the result is a prediction. That is the honest gap in this project.
[add: the mechanism problem that took the longest, e.g. backlash in the torque path, servo stall under load, fit inside the airframe diameter]
[add: anything the modal or Fluent results forced you to redesign]
How I would improve it
Bench-test the loaded mechanism, not the free-swinging one. Servo torque and deflection accuracy under a representative aerodynamic load is the number that matters.
Measure the real first mode with an impact test and compare it to the ANSYS prediction before trusting the margin.
[add: one design change you already know you want]
Next steps
Fly it. An instrumented test flight with IMU logging to compare measured attitude error against the simulated 65% reduction.
Hardware-in-the-loop testing so the flight computer drives the real servos against a simulated flight before launch day.
Push the design point: [add: what changes above Mach 0.8, e.g. canard loads, hinge moment, flutter margin].