Trajectory Modeling of GRAD Rocket with Low-Cost Terminal Guidance Upgrade Coupled to Range Increase Through Step-Like Thrust-Curves

Abstract

The paper shows a full 6 DOF modeling for a GRAD rocket in Earth's non-inertial frame. For numerical purposes the modeling is limited to flat Earth approximation. The full motion equations are shown and all terms are explained together with the aerodynamics parameters for the entire flight envelope. Non-linear interpolation is used for aerodynamic coefficients and their derivatives. We present the typical dispersion factors due to rocket production inaccuracies, launch condition variability and atmospheric factors and their relative influence on a guidance implementation package.Next we present a 6 DOF modeling with various step-like thrust-curves while maintain the same total impulse delivered by the original motor. The influence of the step size on the range of the GRAD rocket is investigated together with the dispersion influence. We show that significant range increase can be obtained while using the same propulsion unit with a steplike thrust-curve modification. We also investigate the influence of the step-like thrust-curve on dispersion of such a rocket and the technological possibilities to implement our solution.In the last part of the paper we present a terminal guidance concept 122 mm rockets. A preliminary requirement for IMU units to be used for terminal guidance is shown together with the general guidance algorithm for several trajectories. Performance expectations are shown through the analysis of the IMU units performance as well as flight dynamics of the 122 mm rockets.

Statistical Analysis of Missile's Trajectory Deviation Due to Production Errors

“…The analysis of the warhead manufacturing error effect is performed by the Monte-Carlo simulation. For the case study, an unguided missile of the well-known characteristics [3] is analyzed. Following parameters have been chosen:…”

Range and Accuracy Improvement of Artillery Rocket Using Fixed Canards Trajectory Correction Fuze

“…Whereas to address the issue of extending the range of 122-mm rocket, the conventional method is to alter the rocket motor thrust time curve to increase the rocket motor impulse to achieve maximum burn-out velocity. For example, reference [13] claims that the range can be extended from its existing 20,168 m to 24,443 m with a time delay of 3 s in Thrust-time curve. The other method to increase range is to add impulse thrusters near the rocket's Center of Gravity (C.G) or, more recently, rocket range can be extended by using high lift ratio moveable canards to increase the angle of attack to generate more lift force [14,15].…”

Using a 3D Model to Asses Projectile’s Impact Points Deviation Due to Manufacturing Errors

“…The problem presented in this paper has been addressed in other studies before, for example [3] and [4] where authors analyze the effect that particular disturbances have on missile behavior during flight, but always with a certain level of simplification that prevents their work to be universally applicable to any class of projectile. For example, in [3] authors identify the most influential factors that cause dispersion of projectile trajectories, especially analyzing the effect of mass imbalance.…”

“…Consequently, the authors present a flight model that is suitable only for spin-stabilized artillery projectiles, etc. In [4] authors develop a flight model for non-guided missiles and also present mass imbalance as a disturbance strongly affecting the rocket's flight. But the mass imbalance is introduced exclusively by varying axial moments of inertia, i.e.…”