Tag Archives: Lycoming T53-L-13

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 (VL) 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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26 December 2015

Deputy Sheriff Jim Miller Dalton, flies Copter 7 over the Solimar Fires, northwest of the City of Ventura just after sunrise, 26 Decmber 2015. Jim has been flying all night. (KABC)
Deputy Sheriff Jim Miller Dalton flies Copter 7 over the Solimar Fire, west of the City of Ventura, at sunrise, 26 December 2015. Jim has been flying all night. (Ventura County Sheriff’s Department Air Unit)

26 December 2015: Shortly before midnight, Christmas Day, a wind-driven fire threatened the tiny coastal community of Solimar Beach, just west of the City of Ventura, California. Low humidity and gusty winds whipped the fire out of control and emergency evacuations were ordered. Winds were clocked at 42 miles per hour (19 meters per second). Highway 1, California’s famous Pacific Coast Highway (or just “PCH”) was closed to traffic in both directions.

Jim Dalton makes a water drop over the Solimar Fire during the night of 25–26 December 2015.
Jim Dalton makes a water drop over the Solimar Fire during the night of 25–26 December 2015. (Cal Fire)

Almost immediately, Copter 7 flew from the Ventura County Sheriff’s Department Air Unit base at nearby Camarillo Airport (CMA). The pilot of the helicopter was Deputy Sheriff Jim Miller Dalton, a 45-year-veteran helicopter pilot who has served with the Air Unit for more than twenty years.

The Solimar Fire, looking west from the City of Ventura, 26 December 2015. (Austi V. Campbell)
The Solimar Fire, looking west from the City of Ventura, 26 December 2015. (Austi V. Campbell)

Copter 7 is a 1970 Bell HH-1H Iroquois, originally a U.S. Air Force rescue helicopter, serial number 70-2472, and now carrying the FAA registration N205SD. The HH-1H was a variant of the U.S. Army UH-1H transport helicopter.

The Bell Helicopter Co. UH-1H Iroquois (Model 205A-1) is an improved variant of the UH-1D (Model 205), which was itself derived from the UH-1B (Model 204). The type’s initial military designation was HU-1, and this resulted in the helicopter being universally known as the “Huey.”

The UH-1H is a single main rotor/tail rotor medium helicopter powered by a turboshaft engine. It can be flown by a single pilot, but is commonly flown by two pilots in military service. The helicopter has an overall length of 57 feet, 0.67 inches (17.375 meters) with rotors turning. The fuselage is 41 feet, 5 inches (12.624 meters) long. The two blade semi-rigid, under-slung main rotor has a diameter of 48 feet, 3.2 inches (14.712 meters), and turns counter clockwise when viewed from above. (The advancing blade is on the helicopter’s right.) At 100% NR, the main rotor turns 324 r.p.m. The two blade tail rotor assembly has a diameter of 8 feet, 6 inches (2.591 meters). It is on the left side of the pylon in a pusher configuration and turns counter-clockwise as seen from the helicopter’s left. (The advancing blade is above the axis of rotation.) The helicopter has a height of 13 feet, 7.4 inches (4.150 meters), measured to the top of the mast.

The UH-1H is powered by a Lycoming LTC1K-4 (T53-L-13) turboshaft engine rated at 1,400 shaft horsepower, though it is 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 UH-1H has a maximum gross weight of 9,500 pounds (4,309.1 kilograms). Its maximum speed, Vne, is 124 knots (143 miles per hour, 230 kilometers per hour). With full fuel, 206.5 gallons (781.7 liters), the helicopter has a maximum endurance of three hours.

5,345 UH-1H Hueys were built, and many of the earlier UH-1Ds were upgraded to the UH-1H standard.

Copter 7, the Ventura County Sheriff’s Department HH-1H helicopter, was rebuilt and upgraded to Bell’s Huey II configuration in 1998. The revised aircraft features the driveline and rotors of the more powerful Model 212. The tail rotor has been moved to the right side of the tail rotor pylon in a tractor configuration, reversing its direction of rotation to clockwise, as seen from the helicopter’s left side. (The advancing blade is below the axis of rotation.) The original 1,400 shaft horsepower Lycoming T53-L-13 has been replaced with a T53-L-703, rated at 1,800 shaft horsepower (de-rated to the transmission limit). This engine is more durable, more fuel-efficent and increases the Huey’s maximum gross weight to 10,500 pounds (4,763 kilograms). The overhaul interval (TBO) increases from 2,400 hours, to 5,000 hours. The Huey II is optimized for “hot and high” operation, with increased hover ceilings, both in (HIGE) and out (HOGE) of ground effect.

Copter 7 also uses the BLR Aerospace FastFin for improved tail rotor performance. Water is dropped from a Simplex Aerospace Model 304 Fire Attack System which can carry 369 gallons (1,397 liters) of water, and is equipped with a snorkel to allow the helicopter to take on water while hovering over a source.

Dalton’s helicopter was soon joined by Copter 16, a Sikorsky S-70A Fire Hawk of the Los Angeles County Fire Department. Mutual aid between agencies is critical with limited air attack resources available.

Copter 16, a Sikorsky S-70 Fire Hawk operated by the Los Angeles County Fire Department, makes a water drop on the Solimar Fire, early on the morning 26 December 2015. (Cal Fire)
Copter 16, a Sikorsky S-70 Fire Hawk operated by the Los Angeles County Fire Department, makes a water drop on the Solimar Fire, early on the morning 26 December 2015. (Cal Fire)

After sunrise, Copters 7 and 16 were joined by two more Huey air attack helicopters from the Santa Barbara County Air Support Unit and Cal Fire, along with four fixed-wing air tankers. More than 600 firefighters fought the flames from the ground. Two of them were injured.

By early afternoon on the 26th, the Solimar Fire was contained after burning 1,236 acres (500 hectares). Traffic was restored and residents were allowed to return to their homes.

The fire was caused by arcing power lines.

The Ventura County Sheriff’s Department also operates a Bell 206L-1 LongRanger II (Copter 3), Bell 205A-1 (Copter 8), and a Bell 212 (Copter 9).

© 2016, Bryan R. Swopes

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