$234 and More Church Business - Saturday, August 9, 1902
The History: Octave Chanute replies to Wilbur's letter of July 31, 1902. The machine (glider) Lamson is building for Chanute has cost $234 so far. Chanute has asked Lamson to ship the oscillating wing glider by August 20, so that it will arrive in Kitty Hawk in time to be tested.
Based on Wilbur's comments in his letter of July 31st, Chanute is concerned that perhaps Wilbur did not understand Merrill's glider design. Chanute agrees with Wilbur: "experience is a much better guide then reasoning in the present state of the art". (Chanute is referring to glider construction.) Testing the design, not talking and arguing about it will demonstrate whether the machine works or not!
Merrill's design has the wings staggered (not directly above one another). Chanute tells Wilbur that although he himself did not have good results with this type of wing configuration ("perhaps I had my surfaces too close to each other"), other designers did. (One of these was Sir Hiram Maxim, the inventor of the rapid-fire gun.) Chanute is glad that Merrill will experiment with this design.
Chanute explains to Wilbur, that Merrill hopes to avoid "interaction" between the different wing surfaces.
Bishop Milton Wright's (Wilbur and Orville's father) diary entries tell us Wilbur has spent this week preparing evidence for the Bishop's trial on August 7th. Wilbur left for Huntington, Indiana on August 5th on the 5:30 train. The bishop himself left on the 5:40 AM train on August 6th. The bishop writes in his diary for August 7th: "after fruitless efforts to agree on the third committeeman, the "court" adjoined at 8:30 PM" [no progress was made]. The bishop came home on Friday, August 8th and Wilbur arrived home today, Saturday August 9th at noon.
Today, airflow interaction still is an important consideration in vehicle design and in many other fields (even sports). The study of air or water and how it interacts and flows over an object is known as fluid dynamics. Although both of these terms have broader definitions, when scientists and engineers study gas flows it is generally referred to as aerodynamics. The study of liquid flows (such as water or seawater) is referred to as hydrodynamics.
Look below at the two submarine pictures. The picture on the left is a model of a World War II submarine. The picture on the right is a model of a modern submarine.
Both models have been immersed in a water tunnel. Yellow dye is injected into the moving water. You can see how the water flows over both submarine models. Compare the two shapes. What is different about them? The WWII submarine has a lot of equipment protruding off its surface, while the modern submarine does not. The modern submarine also has a rounder shape.
Compare the water flow patterns over the two submarines. The flow over the modern submarine remains smooth. For scientists and engineers who study fluid dynamics this is a sign of low drag (low fluid resistance over the body). In general, lower drag goes hand-in-hand with faster speeds. The flow over the WWII submarine is not very smooth. There are quite a few swirls and twists. The water is flowing in many different directions as it strikes the protruding equipment on the older submarine. In general, higher drag indicates slower speeds and indeed the older submarines were much slower than modern submarines.
Look at the videos of our wind tunnel tests of the Wright's 1900 glider. In the stationary glider you can see the air flows fairly smoothly over the wings. In the "wing warping" glider video you can see how the flow burbles off of the wings. Suppose there was another surface behind these wings? The airflow over this additional surface would not be very smooth. So these early flight experimenters may have been trying to reduce this or other types of flow interaction through their designs.