The effect of manufacturing quality on rocket impact point dispersion is analyzed. The approach presented here applies to any type of rocket. Here, manufacturing quality is demonstrated for the unguided rocket, and by simulating four typical manufacturing errors: erroneously manufactured warhead, misalignment between the warhead and engine chamber, asymmetrically installed propellant, and error in nozzle manufacturing. A new methodology is proposed, which combines a 3D CAD model of the asymmetrical projectile (due to manufacturing errors) and the improved Six-degrees-of-freedom (6DOF) model of its flight into a comprehensive Monte-Carlo simulation. In that way, the rocket trajectory dispersion is correlated directly to the imperfection of the manufacturing process. Three quality levels are simulated (low, standard, and high quality), and each of the analyzed manufacturing errors depends on the chosen quality. The results show how important it is to impose the highest quality on nozzle manufacturing, and if this condition is not met, reveal if strict tolerances applied to other steps of the manufacturing process can compensate for the consequential drop of precision.

Continued safe flight under all foreseeable scenarios will be crucial to assure airworthiness and build trust in future vertical takeoff and landing (VTOL) urban air mobility (UAM) concepts. Successful pilot intervention will be especially important for handling emergency procedures. This paper demonstrates the use of human-centric flight guidance concepts to mitigate the effects of non-catastrophic failures in future VTOL UAM aircraft. Specifically, a single failure in the lateral steering function of an automatic flight control system is considered. A new waypoint guidance law is proposed to generate the required roll command to manually steer the aircraft toward a predefined safe landing zone. Two display concepts are proposed to aid the manual execution of the roll steering command: a head-down display (HDD), and a head-mounted display (HMD). The guidance law and the display concepts were integrated into a high-fidelity, wide field-of-view rotorcraft simulation environment. Human-in-the-loop experiments were performed with non-pilot test subjects. The effectiveness of the guidance law and display concepts along with the associated piloting performance and human factor impacts were assessed. The results indicated that all test subjects were able to reach a close vicinity of the final waypoint. The HMD induced lower workload whereas the HDD resulted in better tracking performance.

The angle of attack is one of the most important flight parameters. In the framework of the present study, a flight data recording method was designed to analyze the Valasek angle-of-attack estimation method and investigate its applicability for general aviation aircraft. This was performed using two devices characterized by substantially different characteristics. The test flight, and the ground test, i.e., a flight simulator experiment, were conducted. Two flight regimes were analyzed: (a) steady climb and descent with low values of angle of attack, (b) approach to stall with idle power with an increase of the angle of attack to the critical value. A satisfactory angle of attack estimate was obtained for the steady climb and descent regime, while the approach to stall estimate was less accurate but still indicative and considered useful for the pilot. The results indicate that less expensive synthetic sensors may provide acceptable results compared to high-quality certified equipment. A proposed modification of the estimation method enables simplification of the required equipment, while offering important information to the pilot.

This paper proposes an approach to formulation and integration of the governing equations for aircraft flight simulation that is based on a Lie group setting, and leads to a nonsingular coordinate-free numerical integration. Dynamical model of an aircraft is formulated in Lie group state space form and integrated by ordinary-differential-equation (ODE)-on-Lie groups Munthe-Kaas (MK) type of integrator. By following such an approach, it is assured that kinematic singularities, which are unavoidable if a three-angles-based rotation parameterization is applied for the whole 3D rotation domain, do not occur in the proposed noncoordinate formulation form. Moreover, in contrast to the quaternion rotation parameterization that imposes additional algebraic constraint and leads to integration of differential-algebraic equations (DAEs) (with necessary algebraic-equation-violation stabilization step), the proposed formulation leads to a nonredundant ODE integration in minimal form. To this end, this approach combines benefits of both traditional approaches to aircraft simulation (i.e., three angles parameterization and quaternions), while at the same time it avoids related drawbacks of the classical models. Besides solving kinematic singularity problem without introducing DAEs, the proposed formulation also exhibits numerical advantages in terms of better accuracy when longer integration steps are applied during simulation and when aircraft motion pattern comprises steady rotational component of its 3D motion. This is due to the fact that a Lie group setting and applied MK integrator determine vehicle orientation on the basis of integration of local (tangent, nonlinear) kinematical differential equations (KDEs) that model process of 3D rotations (i.e., vehicle attitude reconstruction on nonlinear manifold SO(3)) more accurately than “global” KDEs of the classical formulations (that are linear in differential equations part in the case of standard quaternion models).