VARIOUS SPEED ITEMS - Derby Tech - February, 1986

Cornell. University has produced research involving the optimum streamlined vehicle. The work was done by Stephen Fugikawa and John Olson of the Sibley School of Mechanical and Aerospace-Engineering. In their papers, they discovered that aerodynamics is very important. The majority of their paper covers their wind tunnel experiments. The work was moslly done on an NACA 0024 airfoil section, and concentrated on determining the optimum airfoil/ground interface.

Some heat treatments will strengthen steels by producing more obstacles (raising each crystal's internal energy), while other heat treatments will soften steels by reducing the number of obstacles (reducing each crystal's internal energy) . The trick to strengthening steels, then, is to produce an optimum number, size, shape, and distribution of different types of slip obstacles by alloying, mechanical processing, and/or heat treatment. Heating increases the vibration of atoms within the metal, so that atoms and crystal defects become mobile and diffuse through the crystal until they. reach positions of lower energy. Specifically, carbon collects in larger and more widely separated carbon particles, while crystal defects link up and annihilate each other. This results in fewer obstacles to inhibit slip, so that metal becomes weaker and more ductile.

Heat treatments depend on both time and temperature, so if the temperature is increased, the tempering time can be reduced. The cooling rate is often a very important factor in heat treatments..

Wind drag takes up 47% of the energy that is used to go 10 mph, 78% of the energy to go 20 mph, and 89% of the energy to go 30 mph.

The secret of streamlining lies in an understanding of the dangerous situation which arises when a boundary layer is required to flow from region of low pressure to a. region of high pressure. If the boundary layer comes to a rest (stalled) the entire flow may be disrupted and with a great increase of drag.

With a thin body having a long tapered tail, like a streamlined airfoil, the rate of pressure rise from shoulder to tail is so moderate that the boundary layer gets nearly all the way to the tail without becoming stalled. This produces no pressure drag.

A shape is said to be streamlined if there is no boundary layer separation.

The object of smoothing components is to avoid sharp edges, corners rapid changes in contour, or shapes that might cause turbulence or unnecessary air resistance. Rough surfaces can also cause excess air friction.

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