These were aerodynamically and structurally accurate models that were flown in a low speed wind tunnel at General Dynamic’s Lindbergh field facility in Dan Diego. We would mount transducers on the model and then fly it at ever increasing speed until (and if) the model went into flutter. We would change weights, engine struts, etc. to reflect different configurations. I would run a piece of test hardware that would monitor the vibration characteristics of the model when it started into flutter. They had this awesome system to drop the speed of the tunnel instantly to zero so save the model from breaking up if it started fluttering badly. They used the results of this testing to predict what would happen on the real thing. Finally, you can see my reflection in the window on the far left.