Tag Archives: Helicopter

19 September 1969

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The first prototype V-24 which first flew September 19, 1969.. (From "Russian Gunship Helicopters" by Yefim Gordon, Page 6)
The first prototype V-24. The stub wings are nearly horizontal. (Image from “Russian Gunship Helicopters,” by Yefim Gordon, Pen and Sword Aviation 2013, at Page 6)
Алфёров Герман Витальевич
Алфёров Герман Витальевич

19 September 1969: After four days of testing in a tethered hover, OKB Mil Design Bureau test pilot Herman V. Alferov made the first free flight of the prototype Mil Mi-24 attack helicopter, V-24.

Designed by a team led by Chief Project Engineer V. A. Kuznetsov, the Mi-24 used the drive train of the Mil Mi-8 Hip-B/C transport and Mi-14 Haze-A anti-submarine helicopters. It had a five-blade main rotor. a three-blade tail rotor and was equipped with retractable tricycle landing gear.

The Mi-24 (named “Hind” by NATO forces) was operated by a pilot and a weapons system operator seated in tandem configuration, with the pilot slightly offset to the left. The gunner is in the forward position. It differed from the American Bell AH-1G Cobra attack helicopter in that it could carry 8 troops or 1,500 pounds (680 kilograms) of cargo in a center fuselage compartment.

Prototype V-24 during test flight. (Unattributed)
Prototype V-24 during test flight. (Unattributed)

The Mi-24 is 17.5 meters (57 feet, 5 inches) long, 6.5 meters (21 feet 4 inches) high, with a main rotor diameter of 17.3 meters (56 feet, 9 inches). As is standard practice with Soviet helicopters, the five-blade main rotor turns clockwise as seen from above. (The advancing blade is on the left.) The tail rotor diameter is 3.9 meters (12 feet, 9½ inches).

The entire fuselage is tilted 2° 30′ (and thus, the transmission, mast and main rotor) to the right to counteract the rotor system’s translating tendency, and helps with high-speed stability.

In early versions, the tail rotor was mounted on the right side in pusher configuration and rotated counter-clockwise as seen from the left. (The advancing blade is above the axis of rotation.) Because of poor handling conditions, the tail rotor was changed to the left side in tractor configuration, with the advancing blade below the hub.

The helicopter’s empty weight is 8,500 kilograms (18,739 pounds) and loaded weight is 12,000 kilograms (26,455 pounds).

Power is supplied by two Isotov TV3-117 turboshaft engines rated at 1,700 shaft horsepower, or 2,200 horsepower for takeoff or one engine inoperative emergency operation.

The Mi-24 has a maximum speed of 335 kilometers per hour (208 miles per hour) and range of 450 kilometers (280 miles). The service ceiling is 4,500 meters (14,764 feet).

Armament consists of a turret-mounted Gryazev-Shipunov GSh-23 23mm cannon with 450 rounds of ammunition. Air-to-air and air-to-ground missiles are carried on pylons mounted under the helicopter’s stub wings.

More than 5,200 Mi-24 attack helicopters have been built, many of them exported. It is estimated that the cost of an individual helicopter is $32,500,000.

Prototype Mil Mi-24 helicopter, which first flew September 19, 1974. (Russian Helicopters photo)
“Red 77,” the prototype Mil Mi-24A helicopter. Note the anhedral of the wings. (Russian Helicopters photo)

Herman V. Alferov (Алфёров Герман Витальевич)—also known as G.V. Alferov or German V. Alferov—was born at Moscow, Russia, U.S.S.R., 11 April 1934. He graduated from the 3rd Moscow Flying Club in 1950, and from 1952 to 1954 was a flight instructor at the Central Aeroclub Chkalov. In 1954,  He graduated from the Voluntary Society of Assistance to the Air Force (DOSAAF) central flight technical school at Saransk in the Mordovian Autonomous Oblast.

Alferov was employed as a test pilot at OKB Mil in Moscow from 1954 until 1982, and remained with the flight test center until 1992. He participated in setting 11 Fédération Aéronautique Internationale (FAI) world helicopter records, and was named an Honored Test Pilot of the Soviet Union, 16 November 1973. In 1977, he was awarded the Order of the October Revolution, twice received the Order of the Red Banner of Labor, and twice the Order of the Red Star.

Herman V. Alferov died 19 January 2012.

Herman V. Alferov with a Mil Mi-4 helicopters.
Herman V. Alferov with a Mil Mi-4 helicopter, circa 1960. (Unattributed)

© 2016, Bryan R. Swopes

14 September 1939

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The prototype VS-300 helicopter clears the ground for the first time, 14 September 1939. Igor Sikorsky is at the controls. (Sikorsky Historical Archives)
The prototype VS-300 helicopter clears the ground for the first time, 14 September 1939. Igor Sikorsky is at the controls. His right foot rests on the anti-torque pedal. (Sikorsky Historical Archives)

14 September 1939: At Stratford, Connecticut, Igor Sikorsky made the first tethered flight of the Vought-Sikorsky VS-300 prototype helicopter. The duration of the flight was just 10 seconds but demonstrated that the helicopter could be controlled.

The Vought-Sikorsky VS-300 was the first successful single main rotor, single tail rotor helicopter.

The three-bladed main rotor had a diameter of 28 feet (8.534 meters) and turned approximately 255 r.p.m. The rotor turned clockwise as seen from above (the advancing blade is on the left). This would later be reversed. A counter-weighted single blade anti-torque rotor with a length of 3 feet, 4 inches (1.016 meters) is mounted on the left side of the monocoque beam tail boom in a pusher configuration and turns counter-clockwise as seen from the helicopter’s left (the advancing blade is above the axis of rotation).

Vought-Sikorsky VS-300 under construction, 8 September 1939. (Sikorsky Historical Archives)
Vought-Sikorsky VS-300 under construction, 8 September 1939. (Sikorsky Historical Archives)

In the initial configuration, the VS-300 was powered by an air-cooled, normally-aspirated, 144.489-cubic-inch-displacement (2.368 liter) Lycoming O-145-C3 horizontally-opposed, four-cylinder, direct-drive engine with a compression ratio of 6.5:1. It was rated at 75 horsepower at 3,100 r.p.m., using 73-octane gasoline. It was equipped with a single Stromberg carburetor and dual Scintilla magnetos. The dry weight of the O-145-C3 was 167 pounds (75.75 kilograms). Later in the VS-300’s development, the Lycoming was replaced by a 90-horsepower Franklin 4AC-199 engine.

On 19 December 1939, the VS-300 was rolled over by a gust of wind and damaged. It was rebuilt, however, and developed through a series of configurations. It made its first free (untethered) flight 13 May 1940.

Test flights continued for several years. After 102 hours, 32 minutes, 26 seconds of flight, the VS-300 was donated to the Henry Ford Museum, Dearborn, Michigan.

Igor Sikorsky adjusts is fedora while at teh controls of the VS-300. (Sikorsky Historical Archives)
Igor Sikorsky adjusts his fedora while at the controls of the VS-300. (Sikorsky Historical Archives)

© 2018, Bryan R. Swopes

7 September 1965

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Bell Model 209 prototype, N209J, in flight with skids retracted. (Bell Helicopter Co.)
Bell Model 209, N209J, prototype of the AH-1G Huey Cobra attack helicopter, in flight with landing skids retracted. (Bell Helicopter Company)

7 September 1965: First flight of the prototype Bell Model 209 attack helicopter. Test pilot William Thomas (“Bill”) Quinlan was in command. The duration of the flight was twelve minutes.

The Model 209 was a private venture, built in just seven months and rolled out at Fort Worth, Texas, 2 September 1965. The prototype aircraft combined the drive system, rotors and tail boom of the production UH-1C gunship with a streamlined fuselage which placed the two pilots in tandem.

The prototype was equipped with retractable landing gear which gave the 209 increased speed, but the expense and complexity were enough that this feature was not included on production aircraft.

This helicopter would be developed into the famous AH-1G Huey Cobra.

N209J,the Bell Model 209 prototype, shown in camouflage colors. (Bell Helicopter Company)
N209J, the Bell Model 209 prototype, shown in camouflage colors. (Bell Helicopter Company)

The second prototype, AH-1G 66-15246, was used by the Army for flight testing at Edwards Air Force Base, California, from 3 April to 21 April 1967.

66-15246 had an overall length of 52 feet, 11.65 inches (16.146 meters) with rotors turning. The fuselage was 44 feet, 5.20 inches (13.433 meters) long, and it was 3 feet, 0 inches (0.914 meters) wide. The HueyCobra had a short “stub wing” with a span of 10 feet, 11.60 inches (3.343 meters). Its angle of incidence was 14°. The wing’s area was 27.8 square feet (2.6 square meters). 66-15426 had an empty weight of 5,516 pounds (2,502 kilograms) and maximum gross weight of 9,500 pounds (4,309 kilograms).

Bell Model 209, N209J, prototype of the AH-1G Cobra, with landing skids extended. (U.S. Army)

The two-bladed Model 540 “door-hinge” main rotor was 44 feet, 0 inches (13.411 meters) in diameter. The blades had a chord of 2 feet, 3 inches (0.686 meters) and 10° negative twist. The main rotor turned counter-clockwise when viewed from above. (The advancing blade is on the helicopter’s right.) Normal rotor r.p.m. (power on) was 314–324 r.p.m., and power off, 304–339 r.p.m. The minimum transient rotor speed, power off, was 250 r.p.m.

The two blade tail rotor assembly had a diameter of 8 feet, 6 inches (2.591 meters) with a chord of 8.41 inches (0.214 meters). There was no twist. It was mounted on the left side of the pylon in a pusher configuration and turned counter-clockwise as seen from the helicopter’s left. (The advancing blade is above the axis of rotation.) The tail rotor pylon was cambered to allow aerodynamic forces in forward flight to “unload” the tail rotor.

Bell AH-1G Cobra three-view drawing. (U.S. Army Aviation Systems Test Activity)

The AH-1G was powered by a Lycoming LTC1K-4 (T53-L-13) turboshaft engine rated at 1,400 shaft horsepower, though it was derated to the helicopter’s transmission limit. The T53-L-13 is a two-shaft free turbine with a 6-stage compressor (5 axial-flow stages, 1 centrifugal-flow stage) and a 4-stage axial-flow turbine (2 high-pressure stages, 2 low-pressure power turbine stages). The T53-L-13 is 3 feet, 11.9 inches (1.217 meters) long, 1 foot, 11.0 inches (0.584 meters) in diameter and weighs 549 pounds (249 kilograms).

The speed of the Cobra was effected by the armament configuration, whether “clean,” light or heavy scout, or “heavy hog.” At 5,000 feet (1,524 meters), the cruise speed in the clean configuration was 138.0 knots (158.8 miles per hour, 255.6 kilometers per hour); light scout, 134.0 knots (154.2 miles per hour, 248.2 kilometers per hour); and heavy hog, 127.0 knots (146.2 miles per hour, 235.2 kilometers per hour). The maximum airspeed in level flight was 149.0 knots (171.5 miles per hour, 276.0 kilometers per hour); 144.0 knots (165.7 miles per hour, 266.7 kilometers per hour); and 136.5 knots (157.1 miles per hour, 252.8 kilometers per hour), respectively.

The limiting airspeed (VNE) was 190 knots (KCAS) (219 miles per hour, 352 kilometers per hour) below 3,000 feet (914 meters) density altitude.

In autorotation, the airspeed for the minimum rate of descent was 74.0 knots (85.2 miles per hour, 137.1 kilometers per hour) with the main rotor turning 294 r.p.m., resulting in a rate of descent of 1,750 feet per minute (8.89 meters per second).

Bell AH-1G Cobra. (U.S. Army)

The basic armament for the AH-1G Cobra was an Emerson M28 turret which could be equipped with one or two General Electric M134 Miniguns, or a combination of a Minigun with a Philco Ford M129 automatic grenade launcher, or two grenade launchers. Each Minigun was supplied with 4,000 rounds of 7.62 NATO ammunition, while a grenade launcher had 300 rounds of 40 × 53 millimeter high-velocity explosive ammunition.

Four hardpoints on the stub wing could be loaded with M18 7.62 NATO Minigun pods; XM35 pods, containing a short-barreled General Electric XM195 20 millimeter Gatling gun (a variant of the M61 Vulcan); rocket pods with seven or nineteen 2.75-inch unguided rockets.

The prototype Cobra, Bell Model 209 N209J, is in the collection of the U.S. Army Aviation Museum, Fort Rucker, Alabama, as is the second prototype, 66-15246.

© 2017, Bryan R. Swopes

27 August 1990

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Bell 206B JetRanger N16933, destroyed on impact, 27 August 1990. All five aboard, including famed guitarist Stevie Ray Vaughan, were killed. (NTSB)

27 August 1990: Four Bell JetRanger helicopters operated by Omniflight Helicopters Inc., arrived at a golf course near Elkhorn, Wisconsin, to pick up various musical artists after a concert at the Alpine Valley Music Theater and to return them to Chicago. They departed at 0040 hours, CDT.

The number three helicopter, Bell JetRanger III (Model 206B-3) serial number 2338, civil registration N16933, was piloted by Jeffrey William Brown of East Chicago, Indiana.

A last minute addition to the passenger complement was electric blues guitarist Stevie Ray Vaughan. Another passenger, Vaughan’s brother, Jimmie Vaughan, switched places with him and boarded a different aircraft.

A third-quarter Moon rose at 12:12 a.m. CST. It was very dark, with thick, patchy fog. The temperature/dew point spread was such that the pilots had to continually wipe heavy condensation from the windshields. Another of the Omniflight pilots later said that the stars were visible when looking up, but that horizontal visibility was variable, with a maximum of about one mile.

Brown, who was not familiar with the area, took off and after about 300 yards, his helicopter banked sharply to the southeast and disappeared into the fog.

The JetRanger impacted a 150-foot hill (45 meters), 0.6 miles away (1 kilometer). It was completely destroyed. All on board were killed. In addition to Brown and Vaughan, the others were Bobby Brooks, Nigel Browne and Colin Smythe, members of Eric Clapton’s tour.

Although the weather was such that the pilot could have reasonably expected to encounter instrument meteorological conditions, Brown did not have an Instrument-Helicopter rating and the Bell 206-series helicopters were not certified for instrument flight.

Below is the accident summary from the National Transportation Safety Board:

NTSB Identification: CHI90MA244 .

The docket is stored on NTSB microfiche number 43569.
Nonscheduled 14 CFR
Accident occurred Monday, August 27, 1990 in ELKHORN, WI
Probable Cause Approval Date: 09/11/1992
Aircraft: BELL 206B, registration: N16933
Injuries: 5 Fatal.

NTSB investigators traveled in support of this investigation and used data obtained from various sources to prepare this aircraft accident report.

FOUR HELICOPTERS WERE BEING USED AT NIGHT TO TRANSPORT A CONCERT GROUP FROM A GOLF COURSE AREA NEAR ELKHORN, WI, TO CHICAGO, IL. AS THE THIRD HELICOPTER (N16933) WAS DEPARTING, IT REMAINED AT A LOWER ALTITUDE THAN THE OTHERS, AND THE PILOT TURNED SOUTHEASTERLY TOWARD RISING TERRAIN. SUBSEQUENTLY, THE HELICOPTER CRASHED ON HILLY TERRAIN ABOUT 3/5 MI FROM THE TAKEOFF POINT. ELEVATION OF THE CRASH SITE WAS ABOUT 100 FT ABOVE THE GOLF COURSE AND 50 FT BELOW THE SUMMIT OF THE HILL. NO PREIMPACT PART FAILURE OR MALFUNCTION WAS FOUND DURING THE INVESTIGATION. PILOTS OF THE OTHER HELICOPTERS REPORTED VFR FLIGHT CONDITIONS WITH SOME FOG. A GROUND WITNESS NEAR THE CRASH SITE REPORTED HAZE AND GROUND FOG OF VARYING INTENSITY WITH PATCHES OF LOW CLOUDS, BUT SAID STARS COULD BE SEEN THROUGH THE FOG.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

IMPROPER PLANNING/DECISION BY THE PILOT, AND HIS FAILURE TO ATTAIN ADEQUATE ALTITUDE BEFORE FLYING OVER RISING TERRAIN AT NIGHT. FACTORS RELATED TO THE ACCIDENT WERE: DARKNESS, FOG, HAZE, RISING TERRAIN, AND THE LACK OF VISUAL CUES THAT WERE AVAILABLE TO THE PILOT.

Stevie Ray Vaughan
Stevie Ray Vaughan

© 2016, Bryan R. Swopes

14 August 1968

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Sikorsky S-61L N300Y, Los Angeles Airways, at Disneyland Heliport, Anaheim, California. (Robert Boser)
Sikorsky S-61L N300Y, Los Angeles Airways, at Disneyland Heliport, Anaheim, California. (Robert Boser)

14 August 1968: At 10:28:15 a.m., Pacific Daylight Time, Los Angeles Airways Flight 417, a Sikorsky S-61L helicopter, departed Los Angeles International Airport (LAX) on a regularly-scheduled passenger flight to Disneyland, Anaheim, California. On board were a crew of three and eighteen passengers. The aircraft commander, Captain Kenneth L. Waggoner, held an Airline Transport Pilot certificate and was type-rated in the Sikorsky S-55, S-58 and S-61L. He had a total of 5,877:23 flight hours, with 4,300:27 hours in the S-61L. Co-pilot F. Charles Fracker, Jr. had 1,661:18 flight hours, of which 634:18 were in the S-61L. Flight Attendant James A. Black had been employed with LAA for nearly ten years.

At approximately 10:35 a.m., while flying at an estimated altitude of 1,200–1,500 feet (370–460 meters) above the ground, one of the helicopter’s five main rotor blades separated from the aircraft which immediately went out of control, started to break up, and crashed in a recreational park in Compton. All twenty-one persons on board, including the 13-year-old grandson of the airlines’ founder and CEO, were killed.

The Sikorsky S-61 was registered N300Y.  It had been the prototype S-61L, serial number 61031. Los Angeles Airways was the first civil operator of the S-61, purchasing them at a cost of $650,000 each. As of the morning of 14 August 1968, 61031 had accumulated a total of 11,863.64 hours flight time on the airframe (TTAF). It flew an estimated 3.17 hours on the morning of the accident.

Los Angeles Airways’ Sikorsky S-61L N300Y. Los Angeles City Hall is at the bottom of the image, just left of center. (AirHistory.net)

The Sikorsky S-61L was a civil variant of the United States Navy HSS-2 Sea King, and was the first helicopter specifically built for airline use. The prototype, N300Y, first flew 2 November 1961. It is a large twin-engine helicopter with a single main rotor/tail rotor configuration. Although HSS-2 fuselage is designed to allow landing on water, the S-61L is not amphibious, having standard fixed landing gear rather than the sponsons of the HSS-2 (and civil S-61N). The S-61L fuselage is 4 feet, 2 inches (1.270 meters) longer than that of the HSS-2. The S-61L is 72 feet, 7 inches (22.123 meters) long and 16 feet, 10 inches (5.131 meters) high, with rotors turning.

The main rotor has five blades and a diameter of 62 feet (18.898 meters). Each blade has a chord of 1 foot, 6.25 inches (0.464 meters). The tail rotor also has five blades and a diameter of 10 feet, 4 inches (3.149 meters). They each have a chord of 7–11/32 inches (0.187 meters). At 100% r.p.m., the main rotor turns 203 r.p.m. and the tail rotor, 1,244 r.p.m. The main rotor turns counter-clockwise, as seen from above. (The advancing blade is on the helicopter’s right side.) The tail rotor turns clockwise, as seen from the left side. (The advancing blade is below.)

The S-61L was powered by two General Electric CT58-140-1 turboshaft engines, each of which was rated for 1,400 shaft horsepower for takeoff and maximum power of 1,500 shaft horsepower for 2½ minutes. The main transmission was rated for 2,300 horsepower, maximum.

The S-61 has a cruise speed of  166 miles per hour (267 kilometers per hour).  The service ceiling is 12,500 feet (3,810 meters). 61031 had a maximum takeoff weight (MTOW) of 19,000 pounds (8,618.3 kilograms).

Between 1958 and 1980, Sikorsky built 794 S-61 series helicopters. 13 were S-61Ls.

Crash scene of Los Angeles Airways’ Sikorsky S-61L N300Y. (Benjamin John Olender/Los Angeles Times, Vol. LXXXVII,Thursday, 15 August 1968, Page 3, Columns 1–4)

The National Transportation Safety Board investigation found that most of the helicopter was contained with a small area of Leuders Park. One main rotor blade, however, was located approximately 0.25 miles (0.40 kilometers) west of the main wreckage. This blade is referred to as the “yellow” blade. (The main rotor blades marked with colored paint for simplicity, red, black, white, yellow, and blue.) Analysis found that this blade’s spindle, where it attached to the main rotor hub assembly, had failed due to a fatigue fracture. It was believed that the fracture began in an area of substandard hardness which was present in the original ingot from which the part was forged, and that inadequate shot-peening of the part during the overhaul process further weakened the spindle.

Diagram of fractured main rotor spindle. (NTSB)
Diagram of fractured main rotor spindle. (NTSB)

Los Angeles Airways had experienced a similar accident only three months earlier which had resulted in the deaths of all 23 persons on board. (Flight 841, 22 May 1968). L.A. Airways never recovered from these accidents and ceased all operations by 1971.

© 2016, Bryan R. Swopes