The knowledge of the roll angle of a projectile is decisive to apply guidance and control law. For example, the goal of ISL's project GSP (Guided Supersonic Projectile) is to change the flight path of an air-defence projectile in order to correct the aim error due to the target manoeuvres. The originality of the concept is based on pyrotechnical actuators and onboard sensors which control the angular motion of the projectile. First of all, the control of the actuators requires the precise control of the roll angle of the projectile. To estimate the roll angle of the projectile, two magnetometers are embedded in the projectile to measure the projection of the earth magnetic field along radials axes of the projectiles. Then, an extended Kalman nIter is used to compute the roll angle estimation. As the rolling frequency of the GSP is about 22 Hz, it is easy to test the navigation algorithm in laboratory. So in previous papers ([1),[5)) the in-lab demonstration of this concept shows that the roll angle estimation was possible with an accuracy of about 1° at 22 Hz. In this paper, the demonstration is extended to in-flight test, with a roll rate about 35 Hz. Thus, two magnetometers, a DSP and a LED (to simulate a thruster) are embedded inside the projectile; the DSP runs an extended Kalman nIter and a guidance algorithm to compute the trigger times of the LED. By using a high speed camera (a trajectory tracker), we can observe that the LED is switch on at the target angle.

Same as Report (SAR) 18. NUMBER OF PAGES 9 19a. NAME OF RESPONSIBLE PERSON

No abstract

Acoustic recordings of artillery shots feature the signatures of the shot's muzzle, projectile, and impact waves modulated by the environment. This study aims at improving the sensing of such shots using a set of synchronous acoustic sensors distributed over a 1 km2 area. It uses the time matching approach, which is based on finding the best match between the observed and pre-calculated times of arrivals of the various waves at each sensor. The pre-calculations introduced here account for the complex acoustic source with a 6-degrees-of-freedom ballistic trajectory model, and for the propagation channel with a wavefront-tracking acoustic model including meteorological and terrain effects. The approach is demonstrated using three recordings of artillery shots measured by sensors which are more than 10 km from the point of fire and distributed at several hundred meters away from and around the target points. Using only the impact wave, it locates the impact point with an error of a few meters. Processing the muzzle and impact and projectile waves enables the estimation of the weapon's position with a 1 km error. Sensitivities of the localization method to various factors such as the number of sensors, atmospheric data, and the number of processed waves are discussed.

ISL's shock tunnel is used as a short blowing ground testing facility to analyze the 6 degrees of freedom motion of a free flying body in order to determine its aerodynamic coefficients. The "Free-Flight Force Measuring (FFM) Technique" was originally described in former literature and has been further developed at ISL's Shock Tube Laboratory using high-speed cameras for observing the translation and the rotation of the body. This paper presents the three tasks that are required to perform the data reduction: 1) measurement of the time-dependent flow parameters as a basis to compute a theoretical motion, 2) accurate observation of the translational and angular motions of the body and 3) estimation of the aerodynamic coefficients using a least-square fit of the measurements to the theoretical motion. The results of the process are tested at Mach 3.0 and Mach 4.5 against the reference aerodynamic data of an Explosively Formed Penetrator (EFP) model. Nomenclature= quadratic yaw drag force coefficient C m = total pitching moment coefficient derivative C m = linear pitching moment coefficient C m = cubic pitching moment coefficient C mq = pitch damping moment coefficient It = model transverse moment of inertia m = model mass M = Mach number p = pressure S = model cross section t = time T = temperature x = downrange displacement u = flow velocity v = model velocity  = angle of attack  = flow density  = model transverse angular velocity