How do we measure efficiency? Pounds of fuel used per mile? A speed or distance calculation?

Take the GEJ79 DASH 19 variant. Thrust is measured at 17,900 lbs on bench I assume but at altitude and speed (25K+ ft and Mach 2+) thrust was theorized by GE engineers to be in excess of 25,000lbs.

Distance covered at Mach 2 is approximately 22 miles a minute.

The -19 F-104 cruised at 70K ft @ M2.0 and burned 100 lbs of fuel per minute. One minute and 100 lbs of fuel covers 22 miles. This is 4.5 lbs per mile.

Looking at a turbofan, how do we measure efficiency? Same parameters? What if we use the F110 and pick a variant: -129 or the PW 100-200/220. I recall reading here on the board the F-16 clean out ranges the F-104G (non DASH 19) with 4 tanks subsonically (the profile wasn't shared i.e. speed and altitude).

What is so fascinating is the J79 turbojet/airframe is just "getting started" at speed and altitude where the turbofan/airframe is running out of steam. I ran some numbers and calculated the -19 F-104 "could" see 500 miles range cruising at 70K ft and M2.0.

Take the GEJ79 DASH 19 variant. Thrust is measured at 17,900 lbs on bench I assume but at altitude and speed (25K+ ft and Mach 2+) thrust was theorized by GE engineers to be in excess of 25,000lbs.

Distance covered at Mach 2 is approximately 22 miles a minute.

The -19 F-104 cruised at 70K ft @ M2.0 and burned 100 lbs of fuel per minute. One minute and 100 lbs of fuel covers 22 miles. This is 4.5 lbs per mile.

Looking at a turbofan, how do we measure efficiency? Same parameters? What if we use the F110 and pick a variant: -129 or the PW 100-200/220. I recall reading here on the board the F-16 clean out ranges the F-104G (non DASH 19) with 4 tanks subsonically (the profile wasn't shared i.e. speed and altitude).

What is so fascinating is the J79 turbojet/airframe is just "getting started" at speed and altitude where the turbofan/airframe is running out of steam. I ran some numbers and calculated the -19 F-104 "could" see 500 miles range cruising at 70K ft and M2.0.

"Never underestimate the underestimated"

Father 104 Driver; "Everything Else Takes Bird Strikes in The Rear"

Father 104 Driver; "Everything Else Takes Bird Strikes in The Rear"