NASA Leading Edge FRP Vortex Flaps

Vortex Flow Visualization Research Program
F-106B 57-2516, NASA N816NA

Vortex Flap Research Video's

Between 1986 and 1991, after completing its use in the NASA Lightning Strike Research, F-106B 57-2516 NASA NF-106B N816NA while still at Langley was used for In-Flight Flow Visualization research as the flight test vehicle of Vortex Flap, a flight experiment to evaluate aerodynamic characteristics of a sharp, leading-edge vortex flap system made of Fibre-Reinforced Plastic (FRP) (also called fibre-reinforced polymer).

The experiment was an analysis of the wing surface pressure distributions and flow visualization data. N816NA was based at Langley, but was flown out to the NASA Wallops Flight Facility, Wallops Island, VA. The final flight was made on 30 Apr 1991.

This flight validation program was conducted at the NASA Langley Research Center to perform "vortex flap" research to improve the aerodynamic performance of delta wing aircraft at high angles of attack and to verify the design tools and expected performance benefits for the vortex flap concept. The primary emphasis of the flight program was the measurement of pressure profiles along the vortex flap and wing to provide verification of design techniques.  Subject of a large NASA and industry effort, the investigation also included analytical and wind-tunnel studies. You can see the specially-designed vortex flap extension on the leading edge of the wing. The flap concept controlled the characteristics of the vertical flow shed off the leading edge of the swept delta wing during flight. Mounted on the spine of the fuselage, the backbone, is a scanning flow-visualization system [the black hump on the backbone], and the white lines on the upper surface of the right wing are pressure belts.

The flight tests established a data base on the use of a wing leading-edge vortex flap as a means to validate the design and analysis methods associated with the development of such a vortical flow-control concept.  The overall experiment included: refinements of the design codes for vortex flaps; numerous wind tunnel entries to aid in verifying design codes and determining basic aerodynamic characteristics; design and fabrication of the flaps, structural modifications to the wing tip and leading edges of the test aircraft; development and installation of an aircraft research instrumentation system, including wing and flap surface pressure measurements and selected structural loads measurements; ground-based simulation to assess flying qualities; and finally, flight testing.

Fibre-reinforced plastic is a composite material made of a polymer matrix reinforced with fibres. The fibres are usually glass, carbon, basalt or aramid, although other fibres such as paper or wood or asbestos have been sometimes used. The polymer is usually an epoxy, vinylester or polyester thermosetting plastic, and phenol formaldehyde resins are still in use. FRPs are commonly used in the aerospace, automotive, marine, and construction industries...

Process definition

A polymer is generally manufactured by Step-growth polymerization or addition polymerization. When combined with various agents to enhance or in any way alter the material properties of polymers the result is referred to as a plastic. Composite plastics refer to those types of plastics that result from bonding two or more homogeneous materials with different material properties to derive a final product with certain desired material and mechanical properties. Fibre reinforced plastics are a category of composite plastics that specifically use fibre materials to mechanically enhance the strength and elasticity of plastics. The original plastic material without fibre reinforcement is known as the matrix. The matrix is a tough but relatively weak plastic that is reinforced by stronger stiffer reinforcing filaments or fibres.

F-106B 57-2516 [NASA NF-106B N816NA] was officially retired in 1992 and is now on static display in the Virginia Air and Space Center in Hampton, Virginia. (data source: NASA)

The papers included below include reviews of the operational aspects associated with the flight experiment, which includes a description of modifications to the research airplane, the overall flight test procedures, and problems encountered.  Selected research results are also presented to illustrate the accomplishments of the research effort.


"In-Flight Flow Visualization Results of the F-106B with a Vortex Flap Results" [3MB PDF]
2003 Report by Jay M. Brandon, James B. Hallissy, Philip W. Brown and John E. Lamar of the NASA Langley Research Center dated March 2003.

"In-Flight Flow Visualization Results of the F-106B with a Vortex Flap Results Report" [4.8MB PDF]
2001 Report by Jay M. Brandon, James B. Hallissy, Philip W. Brown and John E. Lamar of the NASA Langley Research Center as presented Symposium, Loen Norway, 7-11, 2001.

In 1985 NASA took F-106B 57-2507 and cut in in half lengthways in order to use the left side of the aircraft and wing in Wind Tunnel tests for the Virtex Flap In-Flight Flow Visualization project.  NASA called it the F-53 Full Scale Wind Tunnel Test.  Here is a 1985 Article in the 16 Mar 1985 Flight International where NASA sawed the F-106B in-half for testing the vortex flaps on the remaining wing in the wind tunnel.  [Flightglobal archives]

Article in the 17 Sep 1988 Flight International [from the Flightglobal archives]