Sanger M. Burk

Drag Characteristics and Dynamic Stability in Descent of a Rotary Parachute Tested in a Vertical Tunnel

Ralph W. Stone

An investigation was made in the Langley 15-foot free-spinning tunnel to determine the effect of horizontal-tail position on rudder hinge-moments at attitudes simulating spinning conditions. Hinge-moment measurements were made on an unbalanced rudder on a rectangular vertical tail for six positions of the horizontail tail. The hinge-moment measurements were supplemented by tuft tests to determine the air flow about the vertical tail.

Effect of Horizontal-tail Position on the Hinge Moments of an Unbalanced Rudder in Attitudes Simulating Spin Conditions

Spin-tunnel tests have been conducted on dynamic models of two fighter airplanes to explore the feasibility of using deployable flexible ventral fins as an emergency spin-recovery device. Various fin configurations, deflections, and locations were tested. The results indicated that the fins provided satisfactory spin recoveries for the models tested.

Exploratory Wind-tunnel Investigation of Deployable Flexible Ventral Fins for Use as an Emergency Spin-recovery Device

A drop-test investigation has been conducted to determine the stability and drag characteristics of radially vented (duplex) parachutes. Parachutes of two different designs were tested: a large parachute with high geometric porosity and a small parachute with low geometric porosity designed for the same descent velocity with the same load. The results of the tests show that the large high-porosity duplex parachute was very stable in descent, oscillations averaging about [plus-or-minus]3.40; and the average drag coefficient based on the total canopy area and based on the fabric area alone were approximately 0.38 and 0.55, respectively. The small, low-porosity duplex parachute was also very stable in descent, oscillations averaging about [plus-or-minus]4.50; and the average drag coefficients based on the total canopy area and based on the fabric area alone were approximately 0.62 and 0.79, respectively. The oscillations for the cluster of three solid flat circular parachutes, tested for comparison purposes, were [plus-or-minus]7.10. The average drag coefficients based on the total canopy area and the fabric area alone were approximately 0.64 and 0.65, respectively.

Sanger M. Burk

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