• Zagi is a radio-controlled (RC) flying wing glider introduced in 1996 by Jerry Teisan in California.
• Known in the RC community for:
  • Simplicity
  • Low cost
  • High durability --- often referred to as "nearly indestructible"
• Construction: Lightweight expanded polypropylene (EPP) foam covered with vinyl
• Flight Styles Supported:
  • Slope soaring (hill updraft)
  • Thermal soaring (rising warm air)
  • Electric-powered aerobatics
  • Combat flying
• No tail surfaces: Stability and control achieved through wing geometry and elevons

• High aerodynamic efficiency
• Low drag due to no tail
• Pitch stability from reflex airfoil
• Compact and agile structure

Variants include Zagi 400X, Zagi Fixx, Zagi THL - all maintaining robust and efficient flying-wing principles.

• Type: Swept flying wing (no fuselage or tail)
• Span: Approximately 1.2 m (varies by model)
• Planform: Tapered wing with moderate sweep
• Material: EPP foam, laminated
• Reinforcement: Carbon or fiberglass spar
• Purpose:
  • Enhances natural yaw and pitch stability
  • Provides efficient lift distribution

• Reflex or semi-reflex airfoil
• Upward curvature near trailing edge creates positive pitching moment
• Compensates for lack of tail
• Examples: Zagi-specific foils, MH-series, Eppler reflex profiles
• Allows trimmed hands-off stable flight

• Two elevons on the trailing edge
• Combined function of elevator and aileron
• Symmetric movement provides pitch control
• Differential movement provides roll control
• No rudder - yaw stability through wing sweep and differential drag

• Pusher motor mounted behind center section
• Propeller behind trailing edge for improved aerodynamics
• Battery placed in central fuselage pod

Because it's tailless, the zagi requires careful CG placement. Too far back --> unstable pitch oscillations; too forward --> sluggish response

The physical parameters, aerodynamic coefficients and propulsive (Thrust and Motor) coefficients are extracted from "Small Unmanned Aircraft: Theory and Practice" - Randal W Beard and Timothy W McLain

• Lift Coefficient

  $C_L = [(1-\sigma(x))[C_{L_0}+C_{L_\alpha}\alpha] + \sigma(x)[2\alpha\sin^2 (\alpha )cos(\alpha)]] + C_{L_q}\frac{c}{2V_a}q + C_{L_{\delta_e}}\delta_e$

  $\sigma(x) = \frac{1 + e^{-M(\alpha - \alpha_0)} + e^{M(\alpha+\alpha_0)}}{(1 + e^{-M(\alpha - \alpha_0)}) (1 + e^{M(\alpha+\alpha_0)})}$

• Drag Coefficient

  $C_D = C_{D_0} + C_{D_p} + C_{D_\alpha}\alpha + \frac{{C_L}^2}{\pi eAR} + C_{D_q}\frac{c}{2V_a}q + C_{D_{\delta_e}}\delta_e$

• Pitching Moment Coefficient

  $C_m = C_{m_0} + C_{m_\alpha}\alpha + C_{m_{\delta_e}}\delta_e + C_{m_q}\frac{c}{2V_a}q$

• Side Force Coefficient

  $C_Y = C_{Y_0} + C_{Y_\beta}\beta + C_{Y_p}\frac{b}{2V_a}p + C_{Y_r}\frac{b}{2V_a}r + C_{Y_{\delta_a}}\delta_a $

• Rolling Moment Coefficient

  $C_l = C_{l_0} + C_{l_\beta}\beta + C_{l_p}\frac{b}{2V_a}p + C_{l_r}\frac{b}{2V_a}r + C_{l_{\delta_a}}\delta_a $

• Yawing Moment Coefficient

  $C_n = C_{n_0} + C_{n_\beta}\beta + C_{n_p}\frac{b}{2V_a}p + C_{n_r}\frac{b}{2V_a}r + C_{n_{\delta_a}}\delta_a $

• Propeller Thrust

  $F_{x_p} = \frac{1}{2}S_{prop}C_{prop}((k_{motor}\delta_t)^2-V_a^2)$

$$ \mathbf{f}_p = \frac{1}{2}\rho S_{\text{prop}} C_{\text{prop}} \begin{bmatrix} (k_{\text{motor}}\delta_t)^2 - V_a^2 \\ 0 \\ 0 \end{bmatrix} $$

• Propeller Torque

  $T_p = -k_{T_p}(k_\Omega \delta_t)^2$

$$ \mathbf{m}_p = \begin{bmatrix} (-k_{T_p}(k_\Omega \delta_t)^2 \\ 0 \\ 0 \end{bmatrix} $$