QUESTION:

Does an airfoil within and attached to a wind tunnel structure transfer its lift to, and thus decrease the weight of the tunnel structure itself?

ANSWER from George Kidwell on September 23, 2002:

Sure, any time a force is generated, it has to be withstood and transferred to the next structure. In a wind tunnel test, the model is mounted to a force-measuring balance, which is mounted to a device called a sting that holds the model in the correct position in the airstream. The sting is mounted to positioning motors, which are mounted to the tunnel's foundation and supporting structure. The size and strength of all of the components are designed for the highest possible loads that could be encountered, with a safety factor.

So the lift may indeed be carried through the tunnel structure and offset some structural weight. However, the effect is negligible at best because of the orders of magnitude of the forces involved. The lift from a model is typically in the hundreds or maybe thousands of pounds, depending on many factors. The wind tunnel structural weight is measured in the hundreds or maybe thousands of tons.