THE USE OF AERODYNAMIC LIFT FOR APPLICATION TO HIGH SPEED GROUND TRANSPORTATION

The problem of a wing flying in very close proximity to a solid boundary, the so-called 'ram wing,' is reviewed and a new solution is found using the method of matched asymptotic expansions. The effect of the wing upper and lower surface coordinates on the resulting pressure distribution is shown explicitly for the case of a two-dimensional airfoil. It is shown that for very small clearance ratios a very simple expression is valid for the lift coefficient. On the basis of this simplification on analytic solution is obtained for the case of a flat-plate airfoil operating above a sinusoidal ground plane, which gives the forces and moments due to ground bumps. The longitudinal dynamics of a tracked vehicle designed to utilize aerodynamic lift are then investigated. Attention is focused on the case in which the vehicle body is a lifting surface operating in a rectangular guideway. It is found that, as with an airplane, a single wing gives unacceptable stability characteristics and some kind of stabilizing surface is required. Sample calculations are made for the case of a vehicle with a canard which show that adequate ride quality may be obtained with a reasonably smooth guideway. Some of these ideas are extended to three dimensions. An analytic solution is obtained for the case of a flat elliptical wing with a straight trailing edge which has the minimum induced drag for a given lift. A similar solution is obtained for the case of a wing in a tube. (Author)

• Corporate Authors:

  Massachusetts Institute of Technology

  Fluid Dynamics Research Laboratory
  Cambridge, MA  United States 
• Authors:
  • Barrows, T M
  • Widnall, S E
  • Richardson, H H
• Publication Date: 1970-6

Media Info

• Pagination: 162p* p.

Subject/Index Terms

• TRT Terms: Aerodynamic lift; Air cushion vehicles; High speed ground transportation; Intelligent transportation systems; Pressure; Public transit; Stability (Mechanics); Structural plates
• Uncontrolled Terms: Pressure distribution
• Old TRIS Terms: Advanced systems; Flat plate models; Ram wings
• Subject Areas: Operations and Traffic Management; Public Transportation; Railroads;

Filing Info

• Accession Number: 00039213
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: T70-3 Interm Rpt
• Contract Numbers: DOT-C-85-65
• Files: TRIS
• Created Date: Nov 24 1973 12:00AM