Accession Number:

ADA021965

Title:

Reduction of V/STOL Downwash Effects by Jet Exhuast Flow Control.

Descriptive Note:

Final rept. Jul 73-Jun 74,

Corporate Author:

CIVIL ENGINEERING LAB (NAVY) PORT HUENEME CALIF

Personal Author(s):

• Williams,D. E.

Report Date:

1975-12-01

Pagination or Media Count:

54.0

Abstract:

The performance of VSTOL aircraft is influenced significantly by ground effects during landing and takeoff when the propulsive flow of the aircraft is directly dowward. To mitigate downwash effects, a new landing mat concept was developed at Civil Engineering Laboratory whereby exhaust flow is controlled by either a very thin array of diamond patterns or parallel ribs. The impinging jet flow aligns itself with the long axis of the grid pattern, expanding in two directions along a single line rather than radially outward over the plane of the ground. Grid height or thickness is small compared with jet diameter. A method for calculating grid height was developed by combining Froesslings solution for boundary layer thickness and Glauerts solution for wall jet thickness. Author

Descriptors:

• *TAKEOFF
• *AIRCRAFT LANDINGS
• *DOWNWASH
• *VERTICAL TAKEOFF AIRCRAFT
• *EXHAUST GASES
• *LANDING MATS
• CONTROL SYSTEMS
• VERTICAL ORIENTATION
• JET FLOW
• JET PROPULSION
• GROUND EFFECT
• IMPINGEMENT

Subject Categories:

• VSTOL
• Terminal Flight Facilities
• Jet and Gas Turbine Engines

Distribution Statement:

APPROVED FOR PUBLIC RELEASE