Pratt & Whitney JT9D

Template:Short description

The Pratt & Whitney JT9D engine was the first high bypass ratio jet engine to power a wide-body airliner.<ref name=PW-background/> Its initial application was the Boeing 747-100, the original "Jumbo Jet". It was Pratt & Whitney's first high-bypass-ratio turbofan.<ref>Gunston, Bill. World Encyclopedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. Template:ISBN, p.126.</ref>

DevelopmentEdit

File:P&W JT9D cutaway.jpg

The Pratt & Whitney JT9D high-bypass turbofan engine was developed for the Boeing 747

The JT9D program was launched in September 1965 and the first engine was tested in December 1966. It received its FAA certification in May 1969 and entered service in January 1970 on the Boeing 747. It subsequently powered the Boeing 767, Airbus A300 and Airbus A310, and McDonnell Douglas DC-10. The enhanced JT9D-7R4 was introduced in September 1982 and was approved for 180-minute ETOPS for twinjets in June 1985. By 2020, the JT9D had flown more than 169 million hours. Production ceased in 1990,<ref name=PW-background>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> to be replaced by the new PW4000.

The JT9D was developed from the STF200/JTF14 demonstrator engines.<ref>The Engines of Pratt & Whitney: A Technical History, Jack Connors, Template:ISBN, p.409</ref> The JTF14 engine had been proposed for the C-5 Galaxy program but the production contract was awarded to the General Electric TF39. The engine's first test run took place in a test rig at East Hartford, Connecticut, with the engine's first flight in June 1968 mounted on a Boeing B-52E which served as a JT9D flying testbed.<ref>The Engines of Pratt & Whitney: A Technical History, Jack Connors, Template:ISBN, p.412</ref> In 1968, its unit cost was $800,000,<ref>Aero Engines 1968 Flight International 4 January 1968</ref> $Template:Inflation million today.

DesignEdit

The JT9D introduced advanced technologies in structures, aerodynamics, and materials, which included titanium alloys and nickel alloys, to improve fuel efficiency and reliability compared to the Pratt & Whitney JT3D earlier turbofan.<ref name=PW-background/> The engine featured a single-stage fan, a three-stage low-pressure compressor, and an eleven-stage high-pressure compressor coupled to a two-stage high-pressure turbine and four-stage low-pressure turbine. The JT9D-3, the earliest certified version of the engine, weighed Template:Convert and produced Template:Convert thrust.<ref>The Engines of Pratt & Whitney A Technical History, Jack Connors, Template:ISBN, Table 3</ref>

Pratt & Whitney faced difficulties with the JT9D design during the Boeing 747 test program. Engine failures during the flight test program resulted in thirty aircraft being parked outside the factory with concrete blocks hanging from the pylons, awaiting redesigned engines. Boeing and Pratt & Whitney worked together in 1969 to solve the problem. The trouble was traced to ovalization, in which stresses during takeoff caused the engine casing to deform into an oval shape resulting in rubbing of high-pressure turbine blade tips. This was solved by strengthening the engine casing and adding yoke-shaped thrust links.<ref>Flight International, 13 November 1969, p.749</ref>

JT9D engines powering USAF Boeing E-4A airborne command posts were designated F105.

In 1973, NAVSEA selected the JT9D-70 for use as a high efficiency gas turbine in the 30,000 hp to 50,000 hp class, installing its compressor into the pre-existing FT4 marine gas turbine to create the FT9. The engine had been recommended for provisional acceptance in June 1980, with full acceptance pending for ship-specific installation. The engine was selected by the Navy for use in Rohr Marine's 3,000 ton Surface Effect Ship, and one was to be installed aboard the vessel GTS Asiafreighter.<ref>Groghan, D. A., Miller, C. L (1981). Development of FT9 Marine Gas Turbine (PDF). Paper Number 81-GT-197. The American Society of Mechanical Engineers.</ref><ref>Template:Cite journal</ref>

VariantsEdit

All variants have the same number of compressor and turbine stages.<ref name=TCDS-E20EA/><ref name=TCDS-E3NE/>


Template:Abbr	Model	Certification	Takeoff, dry	Length	Width	Weight	Template:Abbr rpm	Template:Abbr rpm	Template:Abbr	FanTemplate:Efn	Application
15-stage<ref name=TCDS-E20EA>{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>	JT9D-3A	Jan 9, 1970	Template:Cvt	Template:Cvt	Template:Cvt	Template:Cvt	3650	7850	{{#expr:43500/8713round2}}	Template:Cvt	Boeing 747<ref name=TCDS-A20WE>{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>
	JT9D-7	Jun 14, 1971	Template:Cvt	Template:Cvt			3750	8000	{{#expr:45500/8880round2}}
	JT9D-7A	Sep 22, 1972	Template:Cvt	Template:Cvt			3750		{{#expr:46150/8880round2}}
	JT9D-20	Oct 16, 1972	Template:Cvt	Template:Cvt		Template:Cvt	3650		{{#expr:44500/8470round2}}	McDonnell Douglas DC-10<ref name="TCDS-A22WE">{{#invoke:citation/CS1\|citation		CitationClass=web }}</ref>
	JT9D-7H	Jun 19, 1974	Template:Cvt	Template:Cvt		Template:Cvt			{{#expr:45500/8880round2}}	Boeing 747<ref name=TCDS-A20WE/>
	JT9D-7AH	Jun 19, 1974	Template:Cvt						{{#expr:46150/8880round2}}
	JT9D-7F	Sep 30, 1974	Template:Cvt				3750		{{#expr:46750/8880round2}}
	JT9D-7FW	Aug 2, 1982	Template:Cvt						{{#expr:50000/8880round2}}
	JT9D-7J	Aug 31, 1976	Template:Cvt						{{#expr:48650/8880round2}}
	JT9D-20J	Dec 29, 1986	Template:Cvt	Template:Cvt		Template:Cvt			{{#expr:48050/8580round2}}
16-stage<ref name=TCDS-E3NE>{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>	JT9D-59A	Dec 12, 1974	Template:Cvt	Template:Cvt	Template:Cvt	Template:Cvt	3780	8011	{{#expr:51720/9140round2}}	Template:Cvt	McDonnell Douglas DC-10<ref name=TCDS-A22WE/> Airbus A300<ref name=TCDS-A172/>
	JT9D-70A	Template:Cvt	Dec 12, 1974	Template:Cvt			{{#expr:51140/9155round2}}	3780	8011	Boeing 747<ref name=TCDS-A20WE/>
	JT9D-7Q	Oct 31, 1978	Template:Cvt	Template:Cvt			3888	8000	{{#expr:51900/9295round2}}
	JT9D-7Q3	Oct 22, 1979	Template:Cvt	Template:Cvt			3960		{{#expr:51900/9295round2}}
	JT9D-7R4D	Nov 25, 1980	Template:Cvt	Template:Cvt		Template:Cvt	3770		{{#expr:48000/8935round2}}	Template:Cvt	Boeing 767<ref name=TCDS-A1NM/>
	JT9D-7R4D1	Apr 1, 1981	Template:Cvt			Template:Cvt	3810		{{#expr:48000/8915round2}}		Airbus A310<ref name=TCDS-A172/>
	JT9D-7R4E		Template:Cvt			Template:Cvt	3770		{{#expr:50000/8915round2}}		Boeing 767<ref name=TCDS-A1NM/>
	JT9D-7R4E1		Template:Cvt		Template:Cvt	Template:Cvt	3810		{{#expr:50000/8935round2}}		Airbus A310<ref name=TCDS-A172/>
	JT9D-7R4G2	Jul 23, 1982	Template:Cvt			Template:Cvt	3825	8080	{{#expr:54750/9170round2}}		Boeing 747<ref name=TCDS-A20WE/>
	JT9D-7R4H1	Jul 23, 1982	Template:Cvt			Template:Cvt	3810		{{#expr:56000/8915round2}}		Airbus A300-600<ref name=TCDS-A172>{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>
	JT9D-7R4E4	Mar 29, 1985	Template:Cvt			Template:Cvt	3810		{{#expr:50000/8935round2}}		Boeing 767<ref name=TCDS-A1NM>{{#invoke:citation/CS1\|citation	CitationClass=web }}</ref>