Tag Archives: Helicopter

14 September 1939

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

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7 September 1965

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

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27 August 1990

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 first-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.


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


Stevie Ray Vaughan
Stevie Ray Vaughan

© 2016, Bryan R. Swopes

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14 August 1968

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 Angles 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.

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.

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

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13 August 1976

The prototype Bell 222 hovering in ground effect during its first flight, 13 August 1976. (Bell Helicopter TEXTRON)

13 August 1976: At the Bell Helicopter facility at Arlington, Texas, the prototype Model 222 twin-engine helicopter, registration N9988K, made its first flight. During the 42-minute flight, test pilots Donald Lee Bloom and Louis William Hartwig flew the aircraft through a series of hovering maneuvers and transitions to forward flight. A Bell spokesperson described it as, “One of the most successful prototype flights we’ve ever had.”

The prototype Bell 222 in flight with landing gear retracted, 13 August 1976. (Bell Helicopter TEXTRON)

The Model 222 (“Two Twenty-Two”) was Bell Helicopter’s first completely new helicopter since the Model 206 JetRanger series. Classified as a light twin, the aircraft was originally powered by two Lycoming LTS101-650C-3 turboshaft engines. The two-blade main rotor was similar in design to that used on the AH-1 Cobra attack helicopters. The first four prototypes were built with a T-tail configuration, but problems discovered early in the test program resulted in a change to the arrangement used in the production version.

Bell Model 222 prototypye, N9988K, in flight. Note T-tail configuration. (Bell Helicopter)
Bell Model 222 prototype, N9988K, in flight. Note T-tail configuration. (Bell Helicopter TEXTRON)

The Bell 222 is used as an executive transport, a utility transport and an aeromedical helicopter. It can carry a maximum of ten persons, and is operated with either one or two pilots. The 222 is certified for Instrument Flight Rules. The standard aircraft has retractable tricycle landing gear but the Model 222UT replaces that with a lighter weight skid gear.

The Bell Model 222 is 47 feet, 6.16 inches (14.482 meters) long with rotors turning. The helicopter has a maximum height of 14 feet, 7.25 inches (4.451 meters) with the forward main rotor blade against its droop stop. The height from ground level to the top of the vertical fin is 11 feet, 0.56 inches (3.367 meters). The helicopter’s maximum width is 11 feet, 4.0 inches (3.454 meters). The empty weight is 4,555 pounds (2,066 kilograms), and the maximum gross weight is 7,848 pounds (3,560 kilograms).

The fifth prototype Bell 222, N222BX (c/n 47005), in the 40′ × 80′ (12.2 × 24.4 meters) wind tunnel at the NASA Ames Research Center, Moffett Field, California. The man at the lower left corner of the image shows scale. (NASA)

The 222’s main rotor mast is tilted 5° forward and 1° 15′ to the left. This contributes to a higher forward air speed and counteracts the helicopter’s translating tendency in a hover.

The two-bladed, underslung, semi-rigid main rotor system rotates counter-clockwise as seen from above (the advancing blade is on the right.)and turns 324 r.p.m at 100% NR. The main rotor has a diameter of 39 feet, 9.0 inches (12.116 meters). The blades have a chord of 2 feet, 4.6 inches (7.264 meters) and are pre-coned 3° 30′. The two-bladed tail rotor is positioned on the left side of the tail boom and turns clockwise as seen from the helicopter’s left (the advancing blade is below the axis of rotation). The tail rotor’s diameter is 6 feet, 6.0 inches (1.981 meters). The blades’ chord is 10.0 inches (0.254 meters).

The Bell 222 was originally powered by two Lycoming LTS101-650C-3 engines. The LTS101 is a compact, light weight, turboshaft engine. The 2-stage compressor section has 1 axial-flow stage and 1 centrifugal-flow stage. The turbine section has 1 high-pressure gas generator stage and 1 low-pressure free power stage. The LTS101-650C-3 was has a maximum continuous power rating of 598 shaft horsepower (446 kilowatts at 49,159 r.p.m. (N1) at Sea Level, and 630 shaft horsepower (470 kilowatts) at 49,638 r.p.m. for takeoff (5-minute limit). The output shaft (N2) turns 9,545 r.p.m. With one engine inoperative (OEI), the -650C-3 is rated at 650 shaft horsepower (485 kilowatts) at 50,169 r.p.m. (30-minute limit), and a maximum 675 shaft horsepower at 50,548 r.p.m. N1/9,784 r.p.m. N2 (2½-minute limit). The LTS101-650C-3 is 1 foot, 10.6 inches (0.574 meters) in diameter, 2 feet,7.3 inches (0.795 meters) long, and has a dry weight of 241 pounds (109 kilograms).

The Bell 222 has a maximum speed of 130 knots. Its hover ceiling is approximately 9,000 feet (2,743 meters). The service ceiling is 12,800 feet (3,901 meters). The maximum range is 324 nautical miles (373 statute miles/600 kilometers).

During early production, problems were experienced with the LTS101 engines, which were also used on the Sikorsky S-76 and the Aérospatiale AS-350D A-Star. This seriously hurt the reputation and sales of all three helicopters. Bell Helicopter’s parent corporation, Textron, bought the Lycoming factory and modernized it in order to improve the engine. (The engine is now owned by Honeywell Aerospace.) Operators began to replace the two Lycoming engines with a pair of Allison 250-C30 turboshafts, and eventually Bell Helicopter modified the aircraft, marketing it as the Model 230. A four-bladed variant with a longer cabin is called the Model 430.

After the test program was completed, the first prototype, N9988K, was used as a static prop on the popular television series, “Airwolf.”

Bell 222 N34NR, an aeromedical helicopter operated by Air Angels, Inc., Bolingbrooke, Illinois. (Photograph courtesy of Chris Hargreaves)
Donald Lee Bloom

Donald Lee Bloom was born in Tulsa, Oklahoma, 23 April 1932. He was the son of Fred Miles Bloom, a telegraph operator for the Standard Oil Company, and Georgia Randolph Bloom.

Don Bloom attended the University of Houston as a Naval Reserve Officers Training Corps (NROTC) midshipman. He graduated in 1955. Bloom was commissioned as a second lieutenant, United States Marine Corps, 15 September 1955. He was assigned to pilot training at NAS Pensacola, Florida.

Lieutenant Bloom was promoted to the rank of first lieutenant, 15 March 1957. He married Miss Anne Marie Carruthers in Los Angeles, California, 5 September 1958. They would have four children, Susan, Stacy, Robert and Todd.

Lieutenant Bloom was released from active duty in 1960, and joined the Kaman Aircraft Corporation as a test pilot. In 1961, began his 29-year career as an experimental test pilot with the Bell Helicopter Company.

The first production Bell OH-58A-BF Kiowa, 68-16687. Don Bloom flight-tested this type in his investigation of Loss of Tail Rotor Effectiveness. (U.S. Army)

In 1984 the Society of Experimental Test Pilots gave its Iven C. Kincheloe Award to Don Bloom for his experimental research into the Loss of Tail Rotor Effectiveness (LTE).

After flying as a test pilot on 187 projects, Don Bloom retired from the Bell Helicopter Corporation in 1990 as Senior Experimental Test Pilot. He then worked for the Federal Aviation Administration Southwest Region as its Designated Engineering Representative Flight Test Pilot, testing aircraft for government certification. During his aviation career, Bloom flew over 14,000 hours in 102 different aircraft.

In 2011, the Federal Aviation Administration presented its Wright Brothers Master Pilot Award to Don Bloom.

Donald Lee Bloom died 18 July 2017 at Grapevine, Texas. He was buried at the Dallas-Fort Worth National Cemetery, Dallas, Texas.

Don Bloom was a project development test pilot for the Bell AH-1G Cobra. (U.S. Army)

Louis William Hartwig was born at Sherman, Iowa, 26 July 1922. He was the son of Lawrence C. Harwig and Alta May Gaughey Hartwig. He attended Bowie High Schoo in Bowie, Texas.

Lou Hartwig enlisted in the United States Army 8 September 1942. (s/n 17119277) He was assigned to the 304th and 902nd Field Artillery Battalions, 77th Infantry Division.

Lou Hartwig married Miss Katherine Elizabeth Healzer, a school teacher, at Rustburg, Virginia, 19 February 1944. They would have a son, Ronald.

Piper L-4 Grasshopper. (Harry S. Truman Library & Museum)

Hartwig was deployed to the Pacific theater of operations, 24 March 1944. He flew a Piper L-4 Grasshopper as an artillery spotter at Guam and Okinawa. He was discharged from his enlistment 18 June 1944, and commissioned a second lieutenant, 19 June 1944 (s/n O-1821011). Lieutenant Hartwig returned to the United States on 21 November 1945. He was released from active duty 24 January 1946.

Lou Hartwig was one of the early students of the Bell Aircraft Corporation’s helicopter flight school at Niagara Falls Airport, New York. The school was for experienced pilots only, and required 10–15 days to complete. Each student received a minimum 22½ flight hours in a Bell Model 47. The cost of the course was $600. Hartwig was then employed as an agriculture “crop dusting” pilot in California.

While spraying insecticide in a field near Sacramento, California, Hartwig was overcome by the poisonous chemicals and lost consciousness. The helicopter struck power lines and crashed. Hartwig was thrown from the cockpit. Crash investigators described the accident as “unsurvivable.” He spent the next 11 months in hospital.

Lou Hartwig was a test pilot for the U.S. Navy’s HSL-1 ASW helicopter. (Bell Aircraft Corporation)

The Bell Helicopter Company hired Hartwig as a test pilot on 15 February 1955. One of his first projects was flight testing the Model 61, the only tandem rotor helicopter ever produced by Bell. It was used as an anti-submarine warfare helicopter by the U.S. Navy, designated HSL-1.

On 31 January 1961, Hartwig set a Fédération Aéronautique Internationale (FAI) World Record for Speed Over a Closed Circuit of 100 Kilometers Without Payload, when he flew a Bell Model 47J Ranger at an average speed of 168.36 kilometer per hour (104.61 miles per hour).¹

On 2 February 1961, Lou Hartwig flew a Bell Model 47G, N967B, to set three more FAI world records: Distance in a Closed Circuit Without Landing, 1,016.20 kilometers (631.44 miles); ² Speed Over a Closed Circuit of 500 Kilometers Without Payload, averaging 119.07 kilometers per hour (73.99 miles per hour); ³ and Speed Over a Closed Circuit of 1,000 Kilometers, 118.06 kilometers per hour (73.36 miles per hour.⁴ The Model 47G had been modified with an additional fuel tank from the earlier Model 47D-1, and curved landing skids from the Model 47J.

The Bell 533, 56-6723, in one of its many configurations. It was flown with two- and four-bladed main rotors, with and without wings, and with and without turbojet engines. (Bell Helicopter Corporation)

Lou Hartwig worked on the U.S. Army’s High Performance Helicopter project. A pre-production YH-40 Iroquois, serial number 56-6723, was modified into a winged and compound helicopter configuration, designated Model 533. Hartwig flew the helicopter to a speed of 274.6 knots (316.00 statute miles per hour/508.56 kilometers per hour). In 1971, the Vertical Flight Society gave its Frederick L. Feinberg Award to Hartwig.

Mrs. Hartwig died 10 February 1989, in San Diego, California. Lou Hartwig married his second wife, Joanne Dunning, in 1990.

Louis William Hartwig died 12 April 2016, at the age of 93 years. He was buried at the Dearborn Memorial Park, Poway, California.

¹ FAI Record File Number 986

² FAI Record File Number 983

³ FAI Record File Number 989

⁴ FAI Record File Number 990

© 2018, Bryan R. Swopes

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