Lamson's Glider and The Parachute Area of A Wing - Thursday, July 31, 1902
Lamson's Machine: Wilbur tells Chanute the ribs on Lamson's machine resemble the Wright' Airfoil #31 that was tested in their wind tunnel in 1901. [Airfoil #31 has a special historical significance. It is a copy of an airfoil surface that Otto Lilienthal tested.]
Wilbur continues, "From the shape of the ribs of the Lamson machine I should judge that our #31 table will apply nearer than any other as a basis of calculations." [Wilbur is referring to the lift and drag calculations below.]
The ribs of the Wright machines and other early gliders and flying machines formed the wing's shape and provided strength, just as a beam shapes a building and provides strength. The fabric cover over the wings conformed to the shape of the ribs and gave the wing its 3 dimensional aerodynamic shape.
Merrill's Letter: Wilbur also writes Chanute that he is not certain he accepts all Merrill has written about proper glider construction. He tells Chanute they have no need to discuss this, because for all practical purposes "experience" (versus talking about it) will prove whether or not Merrill's ideas will work.
Wilbur tells Chanute he doesn't understand the reluctance of some designers to reduce "the parachute area" of their machines by superimposing the wings one over the other. You can see that the Wrights have a biplane (two sets of wings) and that the wings are superimposed (stacked on top of one another). Instead some designers staggered the wings so that they were not on top of one another.
Early designers may have thought that as a glider descended (lowered its altitude) for landing that the wings could act like parachutes allowing the plane to fall safely. Wilbur comments that "it is practically impossible to induce a machine to fall flatwise from any considerable height".
Wilbur said that the brothers testing did not show any benefits of staggering the wings like "steps" as Merrill and others have proposed.
The Shelter: Wilbur tells Chanute that the building the brothers are erecting should be able to house Chanute's machines. Chanute should not need to erect a separate shelter for his machines.
Wilbur and Orville hope to ship what they need for testing and supplies to Kitty Hawk by the end of the week. Wilbur tells Chanute that he thinks that they will leave for Kitty Hawk on August 20th, but that this might be delayed.