Speed penalty

[IanHarr]

Probably a simple answer!
I am getting penalised in my pilot "report card" for exceeding 250 knots under 10000'. This occurs during take-off, I use full power to take
off and immediately throttle back after the gear is retracted. The plane still reaches about 265knt before slowing to the required 250, even
with auto pilot engaged.(Currently using a 737).
How can I get this right?

[jaskanFactor]

It is safe to takeoff using max power, however this, as you mentioned can lead to overspeed immediatly after takeoff

Solution
-----------

Use a high climb rate initially, to bleed off some of that speed, i noticed that airliners do this while watching some aviation videos on
UTube. Works perfectly, but watch out to reduce the climbrate rate from say 2300 fps to 1400 fps as your speed approaches desired
range, so you dont stall.

[bashdabish]

I set N1 thrust to 90% and use N1 autothrottle after powering up and starting my takeoff roll. No idea if this is a realworld practice but it
works for me.

I then hold my climbrate at just below 20 degrees and adjust as needed to hold speed at around 180-190 or whatever speed I require
during climbout. If I am loosing speed then I decrease my climbrate and vice versa. I then swap to speed specified autothrottle which is
pre-set to 190 (again, whatever is appropriate and takes into consideration any tight turns I may need to make). Once I have completed
any sharp turns I accelerate making sure I stay below 250KIAS until after 10000ft.

Hope this makes sense.

[baoding]

i think if you can reach over 250knots during takeoff, the plane should be pretty light..... and you should rotate into the air as soon as it reaches the Vr speed. which is about 140 normally, 160 if heavy. I'm pretty surprised that you can go that fast on takeoff, the max speed i ever took off was like 190 on a 738 with very light load.

You only need full thrust on takeoff if the plane is very heavy. In real world if you keep your thrust setting at 100% for a long time it will damage
the engine, since the N1 and N2 will be actually above 100%, and will appear red on the engine display. On normal takeoff, you use the TOGA button,
which will give you about 85% thrust, and about 90N1 then enable the A/T after you are airborne.

plus doesn't it exceed the flaps speed limit as well if you took off at 265knots?



Post Edited ( 12-28-08 20:57 )

[lightrail]

Before take-off, preset the autothrottle speed to 240kts. After take off, pull the nose up to 20 degrees, turn on autothrottles, gear up, nose down to
10 degrees, then set your autopilots (assuming default aircraft and not using FMC)

[Valoran]

I concur. When I fly jets I always take-off using the autothrottle to keep the speed down unless I'm on a minimum distance runway or have
obstructions (like mountains) to negotiate. Most modern jets have tons of thrust to spare. The ERJ manuals say that they will taxi on their
own at idle in the pilot doesn't hold down the brakes!

[JeffMcBride]

The CRJ will taxi with throttles down as well it seems.

Here is a question I would like answered. How soon after take off does a real life pilot engage AP in say a 738?
I've been curious to know this.

[Kurtvw]

My understanding is that in the real world the AP is not engaged below 1000ft on departure. Of course sometimes it doesn't get engaged
till much later depending on the pilot and the conditions.

As far as the actual take off roll in a 737, there is no reason to be anywhere near 200 knots on take off. Even with a relatively heavy load,
and about 15 degrees of flaps the 737 will be happy to get off the ground around 140, and often less than that 125 to 130 knots you rotate
it to about 15 degrees nose up, hold it there and let it come up, you should have no problem staying under 250. Keep an eye on the
speed and manage the throttle.

After the inital climb (first 1000 feet or so) you lower the nose and let the plane come up to 250 knots and work out your climb.. This is
about when the AP normally goes on. And flaps start getting pulled up.

In the United States, for the most part there is also a limit of 200 knts within 10 miles of the airport below 10k feet, and for the most part all but the largest
heaviest jets try to operate within that rule too, (in addition to the 250 rule) but exceptions are granted for planes that can't easily do it.



Post Edited ( 01-01-09 00:26 )

[Joeflyer]

I'm sure our 738 guru, Tracker, can provide some helpful hints, right Tracky?