General Electric J85

General Electric J85-5

The General Electric J85 is a turbojet jet engine from the US manufacturer General Electric .

It is an engine with an eight-stage axial compressor, which generates a compression ratio of around 6.7-8: 1, and a two-stage axial turbine. Without an afterburner around 13.1 kN of thrust is generated, with an afterburner 17.1 kN.

The engine was developed as a loss engine for the McDonnell ADM-20 missile and was mass-produced from 1960. Deviating from the original purpose, it was z. B. also used in the Northrop F-5 fighter aircraft and the Saab 105 Ö training aircraft . A total of more than 15,500 engines have been produced to date, of which around 2000 are of the civil version with the designation CJ610. A good 6000 of them are still in use (4/2006). The supply of spare parts is to be ensured by 2040.

Technical specifications

	J85-GE-5J	J85-17A / B	J85-21
Compressor stages	8th	8th	9
Turbine stages	2	2	2
Diameter (mm)	533	450	663
Length (mm)	2657	1029	2972
Weight (kg)	265	181	310
Thrust (kN)	17.1	12.7	22.2
Compression ratios	6.7	6.9	8.3

General Electric CJ610

The civilian derivative of the J85 was announced in May 1960. In its basic design it corresponds to the J85, but does not have an afterburner. They were mainly used in models of the Learjet series, but also in the HFB 320 or in the IAI 1121 .

The following variants were produced:

• CJ610-1 / -4: First in production version. The two variants only differed in the position of the auxiliary gear.
• CJ610-5 / -6: As before, but with more thrust.
• CJ610-8 / -9: More power, available from 1969. Use in IAI 1123 .
• CJ610-8A: Same thrust as -5, but with improved altitude performance and longer life.

Technical data CJ610

Type	length in mm	Diameter in mm	Weight in kg	Starting thrust in kN	Continuous thrust in kN
CJ610-1	1298	449	181	12.7	12.0
CJ610-4	1153	449	176	12.7	12.0
CJ610-5	1298	449	183	13.1	12.4
CJ610-6	1153	449	180	13.2	12.4
CJ610-8	1153	449	185	13.8	13.0
CJ610-8A	1153	449	185	13.8	12.7
CJ610-9	1298	449	191	13.1	13.0

General Electric CF700

The CF700 is also a derivative of the J85, which is used in both civil and military applications. Starting with the basic engine, which was largely retained, a fan stage was added, which radially expands the low-pressure turbine. So it's an aft-fan engine . It was used as standard in versions of the Sabreliner and Dassault Falcon 20 . A total of over 1100 engines of this type were manufactured. Since it can also be operated vertically, it was selected as the drive for the Lunar Landing Training Vehicle . The engine was approved by the Federal Aviation Administration on July 1, 1964. The improved version CF700-2D was approved in early 1968. In 1974 the MTBO could be increased to 3000 hours. The bypass ratio is 1.9: 1, the air throughput 39.9 kg / s.

Technical data CF700

Type	length in mm	Diameter in mm	Weight in kg	Starting thrust in kN	Continuous thrust in kN
CF700-2C	1912	1361	330	18.35	17.8
CF700-2D	1912	1361	334	18.90	18.3
CF700-2D2	1912	1361	334	20.02	18.3

Web links

Commons : General Electric J85  - Collection of Pictures, Videos and Audio Files

• General Electric: GE J85 product page
• General Electric: GE CJ610 product page
• General Electric: GE CF400 product page
• Aircraftenginedesign: J85 picture
• Aircraftenginedesign: CF700 picture