Complete Aircraft Wind Tunnel Model
Rigid scale model featuring wing, fuselage, and horizontal stabilizer with movable internal ballast.
Aerospace & Aeronautical Engineering / Longitudinal Static Stability
FREE TO EXPLORELABORATORY 22 · AEROSPACE & AERONAUTICAL ENGINEERING
Longitudinal Static Stability and Neutral Point Determination
Measure aircraft pitching moment slope dC_m / dC_L across center-of-gravity locations x_cg to determine the stick-fixed neutral point x_np and static margin. Explore interactive wind tunnel simulation, flight dynamics, and aerospace engineering telemetry.
AERODYNAMICS · PROPULSION · FLIGHT DYNAMICS
Your virtual aerospace engineering laboratory.
MOMENT DERIVATIVE DC_M/DC_L—
FLIGHT & TEST CELL TELEMETRY
Ready to sample with x_cg/c = 0.25 dimensionless.
Adjust x_cg/c, then execute aerospace trial.
Aeronautical telemetry and flight states are evaluated rigorously using 64-bit IEEE 754 precision. Residuals reflect ordinary least-squares regression across successive observations. Continuous data structures support high-fidelity aerodynamic modeling.
Aeronautical assumptions and boundary condition limits
Linear stability derivative dC_m/dC_L assumes attached flow and constant wing downwash gradient depsilon/dalpha. Linear regression of dC_m/dC_L against x_cg/c yields a slope of 1.0000 and intercept b = -0.3600, locating the neutral point at x_np/c = 0.3600 with R^2 > 0.999999.
Aeronautical apparatus & wind tunnel sensors.
6-Component Internal Strain-Gauge Balance
Measures pitching moment M_y and normal force L about the reference balance center.
Internal Longitudinal Ballast Slider
Shifts model center-of-gravity location along the chord from x_cg/c = 0.15 to 0.40 with 0.1 mm precision.
Automated Angle-of-Attack Pitch Actuator
Pitches model through alpha = -4 to +10 degrees to calculate moment slope dC_m/dC_L.
Pitot-Static Wind Tunnel Airspeed Monitor
Maintains constant dynamic pressure q_inf at test airspeed V_inf = 35.0 m/s.
Digital Stability Analysis DAQ Workstation
Converts moments to C_m, executes least-squares slope extraction, and computes static margin.
FOLLOW THE METHOD
A reason behind every step.
Measure aircraft pitching moment slope dC_m / dC_L across center-of-gravity locations x_cg to determine the stick-fixed neutral point x_np and static margin. Standardized parameter settings: 0.2, 0.23, 0.26, 0.29, 0.32, 0.35 dimensionless.
01
Model Internal Balance Alignment
Install the complete aircraft model onto the wind tunnel sting balance, zeroing pitching moments at zero aerodynamic load.
02
Initial CG Ballast Setting
Position the internal ballast slider to place center of gravity at the forward limit x_cg / c = 0.20.
03
Wind Tunnel Flow Initialization
Run the wind tunnel to V_inf = 35 m/s, stabilizing dynamic pressure at q_inf = 750 Pa.
04
Pitch Sweep and Moment Slope Extraction
Sweep model incidence through alpha = -2, 0, 2, 4, and 6 degrees, measuring C_m and C_L to extract slope dC_m / dC_L.
05
Systematic Aft CG Translation
Step the internal ballast aft through x_cg / c = 0.23, 0.26, 0.29, 0.32, and 0.35, repeating the pitch sweep at each station.
06
Neutral Point Linear Regression
Plot dC_m / dC_L versus x_cg / c, perform linear regression to verify unity slope m = 1.000, and find horizontal intercept where dC_m/dC_L = 0 to identify x_np / c.
YOUR NOTEBOOK · 0 OBSERVATIONS
Turn measurements into aerodynamic insight.
Points are your recorded observations. The solid regression line validates Longitudinal Static Stability mathematical scaling.
LINEAR REGRESSION FIT · y = mx + b
\frac{dC_m}{dC_L} = \frac{x_{cg}}{c} - \frac{x_{np}}{c} \implies \frac{dC_m}{dC_L} = m \cdot \left(\frac{x_{cg}}{c}\right) + b
| # | Center of Gravity Location x_cg / c (dimensionless) | Moment Derivative dC_m/dC_L (dimensionless) | Center of Gravity Location x_cg / c | Pitching Moment Derivative dC_m / dC_L | Remove |
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