Speed for maximum range
A co-worker has an interview coming up with Cathay Pacific. Since I had been through the interview process, I offered my assistance on a few topics, since I see myself as somewhat knowedgeable in technical fields.
The topic of conversation turned to what should be done to cruise speed as a heavy jet transport burns fuel and becomes lighter as the flight progresses. I was sure that I read that you climb to reduce fuel burn further, and reduce airspeed. Can someone confirm this is correct before I send this guy off with some bad info?
As proof, I offered to draw a thrust required vs. speed curve. I explained graphically how a line drawn from the origin (in no-wind conditions) to a point which is tangent to the thrust curve. The corresponding airspeed on the x-axis represents best range.
The part I cannot remember exactly is does the thrust-required curve move down and to the left as fuel is burned? This would produce the reduced airspeed which I am pretty sure is correct. We logically figured this is correct, since thrust required would be less at lighter weights.
Thanks