McDonnell F-101D/E Tactical Fighter (J-79 engines)

[F119Doctor]

Interesting that while the engines seem similar, the number of compressor stages decreased from 17 (J79), to 11 (YJ93) to 9 (GE4). Not sure about the YJ93, but J79 and the GE4 have similar pressure ratios in the 12-13:1 range.

 

[NMaude]

No doubt the reduction in the number of compressor stages was due to improvements in material-science, knowledge of blade aerodynamics and production techniques enabling each stage to do more work.

 

[Scott Kenny]

No doubt the reduction in the number of compressor stages was due to improvements in material-science, knowledge of blade aerodynamics and production techniques enabling each stage to do more work.

In 1997 when I started my Powerplant Mechanic training, we talked about how you usually got maybe 1.5:1 compression between stages of an axial turbojet, and about 7:1 compression in one centrifugal stage.

I think today the axial compression per stage is over 2.2:1.

 

[NMaude]

In 1997 when I started my Powerplant Mechanic training, we talked about how you usually got maybe 1.5:1 compression between stages of an axial turbojet, and about 7:1 compression in one centrifugal stage.

If the J79 had 17 compressor stages and a pressure-ratio of 13:1 that meant that each stage had a pressure-ratio of 1.16:1.