747??????

[310]

GCD,
Please explain airframe altitude limits while heavy.
Thanks

 

[f9driver]

I think what GCD may have been referring to is the buffet boundry. Optimum altitude was the one that gave you a 1.3G buffet boundry for moderate turbulence or, I think, a sustained 30 deg. bank turn. 2.0g was needed for severe turbulence. The special engines, -7R and -7Q, could get you to an altitude where the wing had little margin above stall in a turn or for turbulence. I know our 747-200 freighter, with -7Q's on a ferry or very light load leg, would get you too high for your own good as we discovered one night when we lost both yaw dampers.
Interesting fact: In the early years Pan Am made crews fly the whole leg with one pilot having his hands on the throttles at all times. The early JT-9D's were so were so critical that a bleed could stick or airflow disrupted and suddenly the EGT would go to a 1000 degs or more and cook the turbines. This went on for a year or more until they improved it with the -3 and -3A mods. On the ground turning 90 degs. while taxiing in a strong wind would do the same and for years the FEO had to keep his hands near or on on the cut-off levers while taxiing. Someone said it was the first large engine that did not have key engine sections proven by military flying as was the B-707 and others. Engine maint. was so expensive it probably contributed something to Pan Ams later demise.

 

[GCD]

Tell me where your living room is and have the beer ready.

The airframe limitation is mostly for the wing to be able to have a 1.3g maneuvering and gust capability at a specific altitude. The engines may be able to do FL450, but the airframe may be too heavy for the wing to provide a 1.3g manuevering and gust load at that altitude. The cruise charts need to be looked at to see what the 1.3g cruise limit is for a specific weight for swept wing airplanes.

I have an accronym for remembering how to select a cruise altitude.

ABCC1.3

A = ATC requirements for direction of flight
B = Best specific range
C = Cruise speed maintained with max continuous cruise thrust
C = Climb capability of at least 300fpm
1.3 = 1.3g manuevering capability

 

[Typhoon1244]

I'm sitting here imagining what it'd be like to buy GCD, F9, Typhoon, and a couple other of you guys a case of beer and sit around my living room till the wee hours.

Can I be the designated driver? (I hate the taste of beer...)

 

[Snakum]

Actually, I should have differentiated between Typhoon the Younger - who is a sharp young Regional Captain and is my hero, and Typhoon the Elder - who flew the big stuff back in the good old days.

Your still my hero, though, and I live my life vicariously through you. Well, except for that part about being the proud parent of a bouncing baby boy. It was a lot of fun but I'm too old to do that again.

Cute little feller though.

Minh Thong