2. Methodology—Wind Tunnel
2.1. Concept and Design
- The flow conditioner was a cylindrical section at the inlet of the tunnel with an internal diameter of 1.4 m and a 9 mm wall thickness. The flow conditioner holds the honeycomb and a mesh screen.
- The reducer took the flow from the 1.4 m internal diameter flow conditioner to the 0.6 m internal diameter test section. This contraction before the test section can also reduce velocity fluctuations and form a more uniform flow. The reducer walls were fabricated from 6 mm bendy ply so that it would fit into the smaller internal diameter of the test section.
- The test section was 2 m long, had an internal diameter of 0.6 m and was formed with 6 mm bendy ply. Due to the length and thin walls of the test section a 77 × 38 mm length of pine was run down each side. The door for the test section was then framed using 75 × 38 mm pine and 17 mm plywood. The frame was then removed and the door cut from the test section. At the bottom of the test section, a metal grille recessed into a plywood ring was placed to protect the fan.
- The diffuser transitioned the flow from the 0.6 m internal diameter test section to the 1 m internal diameter fan housing. The diffuser was also made from 6 mm bendy ply.
- The fan was 1 m diameter and had up to 15 kW available in power. The blade angle was at 23° so was left unchanged. The fan was on wheels, and could be adjusted to meet flush with the diffuser.
2.2.1. General Methods
2.2.2. Flow Conditioner and Fan Grille
3. Methodology—Rocket Systems and Modelling
3.1. Improvements to Airframe and Avionics Stack
3.2. Testing Rocket Stability
- Assemble the rocket with a dummy mass motor.
- Measure the center of mass by balancing the rocket on a beam less than 20 mm wide. Mark the center of mass.
- Fix a pipe clamp, with string tied securely to both ends of the pipe clamp to the rocket, at the measured center of mass.
- Feed the string from both sides of the clamp through the two 4 mm holes on the sides of the wind tunnel. Tie the string around the back of the wind tunnel, and tension the ropes to lift the center of mass of the rocket as close as possible to the holes in the side of the wind tunnel.
- Attach the nose tip of the rocket to the vertical string. The purpose of this string is to prevent an unstable rocket from damaging the walls, or prevent the rocket from falling should the clamps slip. The vertical string should be taut only when the nose of the rocket is close to the wind tunnel walls.
- Start the wind tunnel, and check the rocket straightens at 15, 20 and 30 m/s.
3.3. Rocket Roll Dynamics Modelling
3.3.1. Minimal Model
3.3.2. Parameter Identification
4. Results and Discussion
4.1. Wind Tunnel Flow Quality
4.1.1. Turbulence Intensity
4.2. Tasha III—Launch 1
4.3. Tasha III—Launch 2
4.3.1. Wind Tunnel Step Responses
4.3.2. Flight Data
Conflicts of Interest
Inertia in roll axis (kg/m2)
Air density (kg/m3)
Damping constant (m2)
Torque constant (m)
Roll fin angle (rad)
Cross sectional area (m2)
Roll rate (rad/s)
Proportional and derivative gains
Reference angle (rad)
Time-varying disturbance offset angle parameters (rad)
Measured roll angle (rad)
Open and closed loop numerical solutions to roll equations (rad)
Ranges for α, β in the grid search for parameter identification
Turbulence intensity (m/s)
Standard deviation of wind speed (m/s)
Commanded canard angle (rad)
Measured canard angle by encoder (rad)
Individual canard commands (rad)
Individually measured encoders (rad)
Minimum and maximum canard limits for actuation (rad)
Mean absolute roll rate for open loop and closed loop controllers
Mean absolute roll angle for open loop and closed loop controllers
Open loop input signal into PD controller
The National Aeronautics and Space Administration
University of Canterbury
Computational Fluid Dynamics
Revolutions per minute
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|Property||Smokey||Tasha III Launch 1||Tasha III Launch 2|
|Mass||3.0 kg||3.47 kg||3.99 kg|
|Length||1.52 m||1.51 m||1.51 m|
|Z-axis Inertia||0.00311 kg·m2||0.00361 kg·m2||0.00393 kg·m2|
|Fin material||3D printed ABS||3D printed PLA with fibreglass lamination||3D printed PLA with fibre glass lamination|
|Canards||3D printed ABS||3D printed ABS||Fibre glass moulded|
|Avionics||Subsonic capable||Subsonic capable with spot tracker||Supersonic capable with spot tracker|
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