Bench Test Simulator for Deployable Missile Fins

Overview

Johns Hopkins University Applied Physics Laboratory (APL) supports several missile defense programs for the Navy through their research. The challenge presented to the team from the APL team was to better understand how friction, mass, and spring constants affect the deploy time of missile fins. Deploy time of the fins are a crucial aspect of having a successful missile launch.

Objectives

The objective was to build a physical prototype of a missile fin that can be used for bench testing. APL will use the physical prototype to vary mechanical parameters to measure system performance. Those parameters include the torsional spring stiffness and applied force and features to vary the weight and mass moment of inertia. The outer panel of the fin shall weigh 8-10 pounds and deploy through an angle of 135 degrees in 100 msec.

Approach

– The team started off with research and brainstorming to create our initial design.

– Alpha prototype was constructed out of wood to demonstrate the rotating part of the fin.

– The beta prototype was constructed out of 4140 steel based on research and constraints.

– Tests were conducted on the beta prototype to determine the strength of the system.

– Alterations were made to the final prototype to increase strength and to make room for springs.

– FEA analysis on the inner panel was conducted to validate the strength of the final design.

– Arduino UNO board was used to execute program in the Arduino IDE to use Limit switches to calculate the speed of deployment.

– Limit switches were mounted on a wooden block to define the limit of travel of the fin and calculate the amount of time for the outer panel to be deployed.

Outcomes

– Software was able to track the speed and angle of the fin

– Sensor package can calculate the speed of deployment of the outer panel

– The final prototype is close to completion. The ballast slots still have not been cut out and the axis of rotation isn’t fully lined up.

– The 3D SolidWorks model and force calculations will be valuable to APL to determine forces acting on the system