Peter47
29th Aug 2016, 16:02
I understand from some reading that I was doing that most Boeing 707-120s were upgraded to 120Bs with JT3D turbofans which were considerably more powerful than the original JT3C turbojets shortly into their life. The same was true of 720s but that it was not feasible for the 320 series of the aircraft even though the JT3D which powered the 320B/C was was not that much more powerful than the JT4A. I have a number of questions doubtless showing my ignorance:
Was a lot of work required to re-certify the 120 for turbofan engines? Did the original design envisage fitting new engines or was it just good fortune and conservative design that allowed this?
Was the main reason for fitting new power plants cheaper operating costs, enhanced performance or both? (I suspect that given the low cost of fuel in those days and the poor performance of early 707s it was the latter.)
Why couldn't 320s be re-engined to become 320Bs? Was the 320 at the limit of its design? (And indeed could you have fitted JT3Ds to Conway powered 420s? which would still have been an upgrade?)
Moving on (and this should possibly be in the Questions forum), could you fit upgraded engines to 320 ceos to make them neos once now that the new engines are certified presuming that the engine mass and thrust is similar (and ditto for 737s)?
Emirates would like to see a 380neo. Rolls Royce seems possibly keener than Airbus. Would it actually require a lot of work by the latter? It seems that during the 80s quite a lot of incrementally upgraded engines with ever longer designations by all three manufacturers were fitted to 747-200s.
Was a lot of work required to re-certify the 120 for turbofan engines? Did the original design envisage fitting new engines or was it just good fortune and conservative design that allowed this?
Was the main reason for fitting new power plants cheaper operating costs, enhanced performance or both? (I suspect that given the low cost of fuel in those days and the poor performance of early 707s it was the latter.)
Why couldn't 320s be re-engined to become 320Bs? Was the 320 at the limit of its design? (And indeed could you have fitted JT3Ds to Conway powered 420s? which would still have been an upgrade?)
Moving on (and this should possibly be in the Questions forum), could you fit upgraded engines to 320 ceos to make them neos once now that the new engines are certified presuming that the engine mass and thrust is similar (and ditto for 737s)?
Emirates would like to see a 380neo. Rolls Royce seems possibly keener than Airbus. Would it actually require a lot of work by the latter? It seems that during the 80s quite a lot of incrementally upgraded engines with ever longer designations by all three manufacturers were fitted to 747-200s.