In a very brief Web search, I saw "shape factor" as being the same as, or at least analogous to, "drag coefficient." There were various examples such as cylinders, flow parallel to plate, flow perpendicular to plate, etc. You might not find your exact 4x2 shape (flow onto wide side), but something may come close.

This is a meritorious project. If it proceeds well, I can imagine it saving a number of scissors lifts from tipping over in strong winds (or even in not-so-strong winds). Best of luck on this.

From Wikipedia

Shape factor (boundary layer flow)

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A shape factor is used in boundary layer flow to determine the nature of the flow.

where H is the shape factor, δ ^* is the displacement thickness and θ is the momentum thickness. Displacement thickness is defined as the distance that the surface would have to displace outwards in an inviscid flow in order to give the same mass flow rate deficit as that which exists in the boundary layer. Momentum thickness is defined as the distance that the wall would have to displace outwards in an inviscid flow in order to give the same momentum deficit (per unit width) of the mass flow rate.

The higher the value of H, the stronger the adverse pressure gradient. A high adverse pressure gradient can greatly reduce the Reynolds number at which transition into turbulence may occur.

[edit] Further reading

• F.M. White, "Fluid Mechanics", McGraw-Hill, 5th Edition, 2003.
• B.R. Munson, D.F. Young and T.H. Okiishi, "Fundamentals of Fluid Mechanics", John Wiley, 4th Edition, 2002.
• B. Massey and J. Ward-Smith, "Mechanics of Fluids", Taylor and Francis, 8th Edition, 2006.

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Not really a lot of help, does the college have one of those books or any books on fluid mechanics in the library?

I agree with Tornado's comment about the value of your research.

I suggest that you read a copy of "Fan Engineering" published by Buffalo Forge- there should be a copy in your library.

Check the section on either Pneumatic Conveying, or on Penetrations and Obstructions in Ductwork for values for your surfaces. You will also find the appropriate force vectors to use for wind velocity (expressed in FPM).

I think that you will find that- for a width of 4 inches, ou can essentially use the flat surface directly for resistance. When you compute the forces acting on the sides of the scissors sections, you will get a gradient that will yield the equivalent of the TOTAL side force (at whatever design wind velocity is selected) acting on the mid-point vertically.

When you get that calculation completed, re-calculate using an oval shape (wide side) that would result if a curved shape were attached to the structural members in a way that would allow the curve to be compressed between the members if the scissors is retracted.