It’s looking more and more like our proposed NASA testing will indeed happen. In fact, the testing schedule has been accelerated and we’ve been told to be ready to go by the end of April! Thankfully we’ve already been hard at work getting our new Lenz blades built and sprucing up our old Savonius blades for prime time. In the below photo you can see Charlie assembling the “spines” of the Lenz blades over which well will affix some light plastic sheet. These blades reportedly have some very exciting performance characteristics and we’re looking forward to seeing how they perform in the tunnel.

In addition to making certain the turbine is mechanically ready for the wind tunnel we have also been busy jumping through the hoops that NASA and the Army (which manages the the 7′x10′ wind tunnel we’ll be using) sets up for all prospective wind tunnel users. One of those hoops is a “failure analysis” of the turbine and its component parts to ensure that the turbine won’t fail during testing and harm the tunnel or its operators.

At the suggestion of the extremely helpful tunnel technicians we’ve been working with we decided to forgo the analytical approach to failure analysis and instead go with real-world “proof” testing. This involves showing the turbine can withstand substantially larger loads than it is expected to see in the tunnel by calculating the maximum load it is should see in the tunnel, multiplying that of a factor (say four), and then subjecting the turbine to that load outside the tunnel. If it survives it should pose no threat to the tunnel at the loads it will see.

In this photo we are applying a 40 lb load horizontal to the middle of the turbine to simulate approximately four times the 11 lb force the turbine is expected to see if we test it to our proposed maximum speed of 25mph. I think it’s going to be ok.