The role of nose geometry on the slamming forces during the water entry of a simple harmonic oscillator*

When a solid body impacts an air-water interface, substantial fluid-induced forces may arise that can potentially be detrimental to the impactor. In recent prior work, we demonstrated that introducing an elastic coupling between an impacting hemispherical nose and trailing body can consequently decrease or increase the peak force experienced by the body as compared to the fully rigid case, with the outcome depending sensitively on the parameters. Here, we extend the investigation to axisymmetric impactors with various conical noses, documenting how the threshold between force decrease and increase depends on the cone's opening angle. The acceleration of both the nose and the body during the impact event are directly measured using custom onboard inertial measurement units. Our experimental measurements are compared to predictions from a reduced-order model that considers the excitation of the impactor's elastic mode in response to the hydrodynamic slamming forces arising from the added mass effect.