The original 707-121 were powered by JT3C-6 - (Water Injection)
The original 720-022 were powered by JT3C-7 - (NO Water Injection)
The original 707-227 were powered by JT4A-3
The original 707-321 were powered by JT4A-9
The original 707-436 were powered by R.Co.12
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The airplanes equipped with fans JT3D all had the same fan cowlings.
One variation - small cowl doors JT3D-1, some JT3D-3B
Large cowl doors on JT3D-3B (most had that option) and JT3D-7
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T/C inlet on top of engine nš 2, 3 and 4 for all 707s.
T/C inlet only on top of engine nš 2 and 3 for all 720s.
Exception: American 707-100/300 only had T/C on nš 2 and 3.
Some of American 707-300 had T/C cowl on nš 4, but T/C NOT installed.
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Smoke on takeoff - the worst were JT3C especially with water injection used.
The runway went below RVR minimums for the next 10 minutes.
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Happy contrails