The Wind Tunnel (Page 3)

We would need to mount and secure the large tennis ball in the tunnel. It could not vibrate or oscillate in the tunnel and clearly had to be secure enough not to fly off of the mount and damage the tunnel! We discussed piercing the ball and somehow inserting a steel rod into it. The rod would go through the tunnel wall and be bolted into place. But once the ball was pierced it would lose its round shape. Also what was this rod going to "hold onto" inside the ball?

Greg suggested that we spray the inside of the ball with foam insulation - the type that you use around a door jam in your house to keep cold air out. As you spray the foam out of the can it expands and then hardens. Greg felt that the foam would expand inside the ball. Like blowing up a balloon, the foam would fill the ball evenly and the ball would retain its round shape. The foam would also give the metal rod mount inside the ball something to hold on to - it would act like light weight cement holding the rod in place.

Jim Pallis, one of the Cislunar engineers (and also Jani's husband), also felt that a crank could be added to the ball mount. Using either a small motor or by hand the ball could be spun.

Jani also wanted to test a smooth ball, so that you could see the difference in aerodynamics that the tennis ball fuzz covering causes.

We would need to complete required NASA paperwork and hold a "readiness review". We would have to define the tests, the speeds and spin rates. We would also need to demonstrate that the ball and its mount were safe to use in the tunnel. We agreed that we would meet again in 3 weeks and conduct the readiness review. Off we went!