727 Question

[Groundpounder]

FedEx runs a 727 to FLL out of the airport I work at, and they are normally very heavy when they depart. To me, it looks like the aircraft actually decends after they pull the flaps up on takeoff. Am I seeing things, or does this actually happen?

Thanks

 

[sabreliner]

I believe it is an optical illusion. The A/C doesn't descend. When they pull the flaps up, the a/c climb gradient lessens by a bit while the a/c accelerates. This causes it to look like it is descending, when in fact it is just climbing more slowly.

As a general rule, descents just after t/o are a BAD thing and we try to avoid them.

 

[RichardFitzwell]

That must be an illusion.

Although the 27 isn't a great performer right after takeoff, it doen't descend either.

A heavy -100 will climb at about 800-1200 fpm and a -200 will do a little better. If you want to talk about the Valsan converted 727's...now they're a different story. Hold on tight.

 

[de727ups]

The profile is to climb at V2 plus 10 knots (usually around 145K..depends on weight) to 1000 AGL. Then you lower the nose and accelerate while raising the flaps, shooting for a clean speed of 200 to 250 knots. During this cleanup and acceleration phase the climb rate should be positive...I usually shoot for 500 fpm. With the flaps out and V2 plus 10, depending on weight, you might see 1000 to 1500 fpm climb. Once clean you will see 2000 to 3000 fpm, depending on weight and altitude.

 

[ShawnC]

As a general rule, descents just after t/o are a BAD thing and we try to avoid them.

Understatement of the year

 

[skyking1976]

That guy that lives behind the panel keeps saying, "Don't Sink. Don't Sink." But I'm nowhere near water...

 

[sabreliner]

Isn't that the engineer's job on the '27?

(I mean, they do all the rest of the work!)

 

[CUEBOAT]

According to my buddy that is on the panel of a 727, he does ALL the work.

 

[Huck]

We also go to "Quiet EPR" as the flaps come up, drastically cutting climb rate. Climb power is restored at 3000'.

 

[kabz]

Only kinda related, but go have a look at some piston twin training, and you can clearly see the aircraft sink when the aircraft pulls an engine after takeoff .... ATP flies a seminole out of Houston Southwest and we call it the 'seminole sink' when we see that.

 

[banned username 2]

Only kinda related, but go have a look at some piston twin training, and you can clearly see the aircraft sink when the aircraft pulls an engine after takeoff .... ATP flies a seminole out of Houston Southwest and we call it the 'seminole sink' when we see that.

THAT is one of the differences between a FAR23 and FAR25 aircraft... Required climb performance OIE...