Cruise speeds

[Chairman]

While I was in daydream mode yesterday (driving buses does have its perks ...) I realised something quite bizarre.

In 3 of the propeller aircraft I fly regularly (B58, DC-3, C172) I set the power according to the manual and accept whatever I get for a cruise speed. In the other propeller aircraft I fly regularly (B200) I set the RPM according to the manual then shove on as much power as I can without melting the engines, and accept whatever I get for a cruise speed.

In the jets I fly regularly - 727, 737, 747, 767 - it's the complete opposite. I fly to whatever speed the manual or FMC says I should, and accept whatever it takes to achieve that as a power setting. Even in the almost totally manual 727.

Has anybody else noticed this ? Or does it differently ?

Cheers
Gary

[gojozoom]

I believe, it comes from the differences of the two era. A very good example for that would be the flight planning. Back in the 50's, the ONLY relevant thing was time. The flight looked like this : 1/3 part climb, 1/3 part cruise and 1/3 part descent. They had an "average" speed for the flight (usually 0.77 X economy cruise speed as per manual). On the basis of this speed they calculated the ETA for every navigational point (ADF's and VOR's) they pass. If they were late or early more then 15%, they adjusted the power settings to one "level" up or down. These levels were written down in the manual. They didn't care about their actual speed.ONLY time was important. I fly propliners mostly, and I have to say that I found this method to be the most accurate one for those old birds. You can read some more on propliner flight planning here.
Hope that helps

Smooth landings!