take off performance??????

[gatbusdriver]

Could someone please help me. I have been looking for the answer to this question for most of the day.

What are the four segments used for take off performance?


I believe segment one is from the start of the take off roll to screen height.

Segment 2 might be from screen height to accel height.

But the i'm stumped. Could someone please give me the correct answer.

Cheers

[Mad (Flt) Scientist]

Originally Posted by gatbusdriver

Could someone please help me. I have been looking for the answer to this question for most of the day.
What are the four segments used for take off performance?
I believe segment one is from the start of the take off roll to screen height.
Segment 2 might be from screen height to accel height.
But the i'm stumped. Could someone please give me the correct answer.
Cheers

From FAR 25...

Originally Posted by Amdt 25-72

Sec. 25.111 Takeoff path.
(a) The takeoff path extends from a standing start to a point in the
takeoff at which the airplane is 1,500 feet above the takeoff surface, or at
which the transition from the takeoff to the en route configuration is
completed and a speed is reached at which compliance with Sec. 25.121(c) is
shown, whichever point is higher.
.....
(d) The takeoff path must be determined by a continuous demonstrated
takeoff or by synthesis from segments. If the takeoff path is determined by
the segmental method--
(1) The segments must be clearly defined and must be related to the
distinct changes in the configuration, power or thrust, and speed;
(2) The weight of the airplane, the configuration, and the power or thrust
must be constant throughout each segment and must correspond to the most
critical condition prevailing in the segment;

So, the answer is, as always...."it depends" - upon your type of aircraft, and upon the choices the OEM has made in reducing the data.

If one were to GUESS for a specific aircraft, one might expect segments as follows:

• Ground roll to liftoff
• lift off to 35ft (assumed gear up at 35ft)
• Gear up to flap transition
• clean, final segment

But depending on what configurations you have and what transitions are required, you could easily have extra segments. (Say if you have an intermediate flap position between takeoff and clean...)

[gatbusdriver]

Thanks Mad (Flt) Scientist

I think I have since come accross the answer I was looking for.

I believe that the Take off is from the start of the take off roll to screen height.

You then have the Net Take Off Flight Path which is divided into 4 segments:

1. Screen Height - undercarriage retraction
2. Undercarriage retraction - flap retraction
3. Level acceleration (during flap retraction)
4. Climb (clean) to 1500'

segments 3 and 4 can be combined.

as usual I am probably wrong.

[oldebloke]

Gat,go to www.wingfiles.com,and look up(half way down the items)'geeting to grips with aircraft performance'airbus.....Run the pages off for future reference(200?)
cheers..

[oldebloke]

^That should be 'Getting to'

[john_tullamarine]

Lest folk be perplexed by MFS' answer, be aware that he is an OEM design team man and his answer reflects that background .. ie it addresses a typical engineering model analysis ... however, the operator types will be more interested in the OEI segmented AFM analysis.

Be aware that there may be a fifth segment for some aircraft which generally addresses a final climb speed acceleration.

[gatbusdriver]

Thanks all

for info it was A330

[whatdoesthisbuttondo]

Originally Posted by oldebloke

Gat,go to www.wingfiles.com,and look up(half way down the items)'geeting to grips with aircraft performance'airbus.....Run the pages off for future reference(200?)
cheers..

Great link that one.