NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Collections About News Help Login
Back to Results
Exploratory flow visualization investigation of mast-mounted sights in presence of a rotorA flow visualization investigation with a laser light sheet system was conducted on a 27-percent-scale AH-64 attack helicopter model fitted with two mast-mounted sights in the langley 14- by 22-foot subsonic tunnel. The investigation was conducted to identify aerodynamic phenomena that may have contributed to adverse vibration encountered during full-scale flight of the AH-64D apache/longbow helicopter with an asymmetric mast-mounted sight. Symmetric and asymmetric mast-mounted sights oriented at several skew angles were tested at simulated forward and rearward flight speeds of 30 and 45 knots. A laser light sheet system was used to visualize the flow in planes parallel to and perpendicular to the free-stream flow. Analysis of these flow visualization data identified frequencies of flow patterns in the wake shed from the sight, the streamline angle at the sight, and the location where the shed wake crossed the rotor plane. Differences in wake structure were observed between the sight configurations and various skew angles. Analysis of lateral light sheet plane data implied significant vortex structure in the wake of the asymmetric mast-mounted sight in the configuration that produced maximum in-flight vibration. The data showed no significant vortex structure in the wake of the asymmetric and symmetric configurations that produced no increase in in-flight adverse vibration.
Document ID
19950018146
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Ghee, Terence A. (Analytical Services and Materials, Inc. Hampton, VA., United States)
Kelley, Henry L. (Army Aviation Systems Command Hampton, VA, United States)
Date Acquired
September 6, 2013
Publication Date
March 1, 1995
Subject Category
Aerodynamics
Report/Patent Number
ATCOM-TR-95-A-001
NAS 1.15:4634
NASA-TM-4634
L-17409
Accession Number
95N24566
Funding Number(s)
PROJECT: RTOP 505-59-36-01
PROJECT: RTOP 282-10-01-01
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

Related Records

There are no records associated with this record.
No Preview Available