## 3 Analytical Model and Experimental Setup
### Experimental Setup  
An experiment aiming to explore the effects of the thrust control configuration on the lift, thrust, and pitch moment of a BWB aircraft with distributed electric BLI propulsors was carried out. As illustrated in Figure 13, the experimental platform comprised the three following components: the BWB aircraft, aerodynamic conditions, and measurement devices. The BWB aircraft had a mass of 13.3 kg, a wingspan of 2.5 m, and a center body chord length of 0.982 m. The fuselage dimensions were 1098.41 mm in length, 2461.6 mm in width, and 387.9 mm in height. The aircraft's reference area was 0.9663 m\({}^{2}\), with a reference length of 0.409 m.  
A high-flow-rate thrust control configuration was installed at the rear of the distributed propulsors, equipped with a fixed cascade and two moveable cascades positioned both above and below the BLI fans, each measuring 300 mm \(\times\) 165 mm \(\times\) 3 mm. Two high-strength carbon fiber rods with a diameter of 6 mm were installed at 80 mm from the leading edge on each of the two moveable cascades, with lightweight bearings supporting the rotating shafts. This setup allowed for the adjustment of the moveable cascade\({}^{\prime}\)s deflection during the experiments. A knob was used to adjust the friction between the cascades and the rotation shafts. When the deflection angle needed to be changed, the knob was rotated to reduce the friction, allowing for the cascades to be positioned at the desired deflection angle. The knob was then rotated again to increase the friction, clamping the rotation shafts and securing the cascades\({}^{\prime}\) orientation, ensuring that their position remained fixed during the operation of the BLI fans. An industrial fan was used to provide an incoming flow at 4 m/s, and fine mesh screens were installed upstream of the contraction in order to reduce the turbulence and guarantee a uniform velocity distribution in the test section. A high-precision digital thrust meter (Model SGHF-5), with a measurement range of 0.5-5 N and a resolution of 0.001 N, was employed to accurately measure the thrust force during ground tests. For the experiment, the front landing gear of the distributed propulsion aircraft was placed on the thrust meter, while the rear landing gear was positioned on a smooth, flat surface to minimize friction. Upon the activation of the distributed propulsion system, a specific thrust was generated. Based on a force analysis, the thrust experienced by the distributed propulsion aircraft was equal to the force recorded by the thrust meter. Changes in the readings from the thrust meter under different experimental conditions represent the changes in the overall thrust force of the aircraft. Lift was indirectly assessed using three high-precision analytical balances (model BOLNE, with a capacity of 10 kg and a resolution of 0.001 kg). The landing gears of the BWB aircraft with BLI fans were placed on these balances. Differences in the readings between  
Figure 13: Schematic diagram of the experimental setup for BWB aircraft with novel thrust control configuration. the non-operational and operational states of the thrust control configuration represent the additional lift generated by the configuration. The change in lift was calculated as follows:  
\[L=\Sigma F_{S}-\Sigma F_{D} \tag{6}\]  
where \(\Sigma F_{S}\) and \(\Sigma F_{D}\) are the sum of the forces measured by the balances in the static and dynamic states, respectively. The additional pitch moment generated by the thrust control configuration was calculated as follows:  
\[M=\Big{(}F_{fS}-F_{fD}\Big{)}l_{f}-[\Sigma F_{bS}-\Sigma F_{bD}]l_{b} \tag{7}\]  
where \(l_{f}\) is the lever arm length from the front landing gear to the center of gravity, and \(l_{b}\) is the lever arm length from the midpoint between the two back landing gears to the center of gravity. These lever arm lengths were measured under static conditions. \(F_{fS}\) and \(F_{fD}\) represent the individual forces on the front landing gear measured under static and dynamic states, respectively.