ASE 446: Helicopter Aerodynamics and
Design
Forward Speed Limitations
Asst. Prof. Dr. Anna Prach
METU NCC
AEROSPACE ENGINEERING
Forward Speed Limitations
Dr. Anna Prach
Forward Speed Limitations
•
Forward velocity is limited by:
•
•
•
Blade stall on the retreating side.
Shock induced flow separation on the advancing side.
Due to these limiting factors, the maximum forward speed of a
helicopter is limited to about 250 mph (402 km/h).
Dr. Anna Prach
Forward Speed Limitations
•
1986, Westland Lynx: 216 knots (249 mph; 400 km/h).
Dr. Anna Prach
Forward Speed Limitations
•
2010, Sikorsky X2: 225 knots (259 mph; 417 km/h).
Dr. Anna Prach
Forward Speed Limitations
•
2013, Eurocopter X³: 255 knots (293 mph; 472 km/h) in level flight, 263
knots (303 mph; 487 km/h) in a shallow dive.
Dr. Anna Prach
Forward Speed Limitations
•
•
•
Sikorsky-Boeing SB-1 Defiant: It is a compound helicopter.
The first flight expected in 2019.
The design will have a cruise speed of 250 knots (460 km/h).
Dr. Anna Prach
Flow field complexity in forward flight
Dr. Anna Prach