Retreating blade stall

August 3, 2013 - 2:20am
The Eurocopter X3 technology demonstrator flew at 255 knots in level flight, an unofficial record for a helicopter, on June 7. It also reached 263 knots in a dive. “It’s no exaggeration to say that the X3 is clearly in its element at high speeds,” said Hervé Jammayrac, Eurocopter test pilot.

The Eurocopter X3 hybrid made its record-breaking speed run just 10 days before the opening of the Paris Air Show, so it was not surprising that the EADS company brought both the unique aircraft and its crew to the Le Bourget biennial event. On June 7, the X3 flew at 255 knots in level flight and 263 knots in a dive, besting the previous record set by the Sikorsky X2 in September 2010 (250 knots level and 260 knots in descent).

May 1, 2013 - 2:55am

On April 9, the NTSB held a public meeting to discuss the crash of a LifeNet helicopter in Mosby, Mo., on Aug. 26, 2011. The Eurocopter AS350B2 ran out of fuel, according to the NTSB, and the pilot failed “to successfully enter an autorotation when the engine lost power due to fuel exhaustion.” What the pilot did not do, the Board explained, is move the cyclic control aft when the engine failed.

April 1, 2013 - 12:30am
Air blown through small holes in the blade makes dynamic stall less severe in demanding maneuvers, according to researchers at DLR.

Researchers at the German Aerospace Center (DLR) in Göttingen may have discovered a way to make helicopters more maneuverable, by reducing the dynamic load on the rotor head control rods.

During rapid forward flight or maneuvering, airflow stalls on the main rotor blade as it retreats (moves backwards), giving rise to a “dynamic stall” and subjecting the rotor head control rods to formidable dynamic loads.

December 5, 2011 - 12:30pm

Safe Flight Instrument is celebrating its 65th anniversary with several new programs, including a speed-control system for the Cessna 400 and 208, Lancair Evolution, Quest Kodiak and Viking Twin Otter and autothrottles for the Gulfstream G150, Cessna Citation X and Hawker 800 series.

April 18, 2008 - 11:42am

In the aeronautical mountain range, a few peaks are still unclimbed. Some goals, once thought impossible, are an everyday fact. Jet propulsion, supersonic flight, a practical helicopter and the miracles of manned and unmanned spaceflight all whiz past our bemused faces while we scarcely register a raised eyebrow.

October 12, 2007 - 7:54am

In the arcane world of helicopter rotor aerodynamics, two concepts that show promise for enhancing safety and performance in the world of high-density-altitude heavy lift are under development on opposite sides of the U.S. Briefings on both were presented at the American Helicopter Society’s annual forum last month in Phoenix.

July 25, 2007 - 6:47am

Retrofit technology that could turn the Pentagon’s fleet of Black Hawks and other helicopters into 200-knot, high-altitude speedsters, and later be applied to the civil market, is one step closer to reality.

 
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