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simpilot1

Take-off run 777

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Gentlemen,

 

I have a question because it might takes to Long until V1 is reached during take-off run.

Sometimes I consume nearly the hole runway lenght before reaching V1 (e.g. 77W at Dubai 80% load).

 

How Long do you think or know a take-off run should due with following Parameters?

 

PMDG 777F

TOW 313.000 KGS

ZFW 236.000 KGS

FUEL 77.000 KGS

Runway ELV 12'

Altimeter 30.23

Derated Thrust 38° C; 98.6% Thrust

Procedure

Full breaks, increase thrust to 50%; push TOGA wait until 98.6% thrust is reached; breaks off.

 

Please let me know your comments I have measured it for myself and going to compare.

 

Thank you.

 

Andreas Hövel

 

 

 

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Please let me know your comments I have measured it for myself and going to compare.

Need to know wind direction/speed, OAT, and runway L or R. They are different lengths.

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Gentlemen,

 

I have a question because it might takes to Long until V1 is reached during take-off run.

Sometimes I consume nearly the hole runway lenght before reaching V1 (e.g. 77W at Dubai 80% load).

 

How Long do you think or know a take-off run should due with following Parameters?

 

PMDG 777F

TOW 313.000 KGS

ZFW 236.000 KGS

FUEL 77.000 KGS

Runway ELV 12'

Altimeter 30.23

Derated Thrust 38° C; 98.6% Thrust

Procedure

Full breaks, increase thrust to 50%; push TOGA wait until 98.6% thrust is reached; breaks off.

 

Please let me know your comments I have measured it for myself and going to compare.

 

Thank you.

 

Andreas Hövel

Have you tried not to derate your engines? (The only thing I know is that emirates don't derate with their 777's)

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Yes I did.

But I had never again the feeling of more than enough thrust

after reinstalling my rick with all the FS stuff.

 

I think derating the engines is a quit normal procedure in order to secure engine long term liability.

 

My example from today with 777F at KJFK shows 98,6% deratet thrust which is not as less to expect

to use nearly the hole runway length and even the feeling how the aircraft increases speed on the

runway is, let say not to compare with potential engine power.

 

 

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Yes I did.

But I had never again the feeling of more than enough thrust

after reinstalling my rick with all the FS stuff.

 

I think derating the engines is a quit normal procedure in order to secure engine long term liability.

 

My example from today with 777F at KJFK shows 98,6% deratet thrust which is not as less to expect

to use nearly the hole runway length and even the feeling how the aircraft increases speed on the

runway is, let say not to compare with potential engine power.

Do you use any live weather app for instance like ASN? Maybe it is because of the outside temperature/airpressure mix.. or even a bug!

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simpilot1, on 05 Sept 2015 - 11:09 AM, said:

Today example with 777F is from Takeoff KJFK

RWY 04L

22° C OAT

Wind 060 / 04

Rwy length 11350 feet

I show 04L at KJFK as 12079 feet long. I used an altimeter of 30.29 which was what it was at 1451Z. Anyway, using the figures from post 1 and 3 and flaps 5. I show at 38 degrees assumed temperature a V1 of 166 kts. a VR of 172 kts. and 2993 feet remaining at liftoff.

 

To get any meaningful figures I believe the weather needs to be a standard day (wind 00/00, A 29.92 and the OAT 15C at sea level) and the airport needs to be constant.

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98.6% Thrust

What is the fascination with 98.6 thrust? Do you adjust your assumed temperature and use either D1 or D2 to achieve 98.6 thrust?

 

98,6% deratet thrust

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the numbers i got from TOPCAT are pretty similar, for 34C, 29.80 it calculated D-TO at 44C

this resulted in a max of 98.5%

 

the takeoff roll seemed pretty long but not unusually so, i did not measure the distance but it looks like i hit v1 right around the last big turnoff

 

here is a vid of the takeoff roll

https://youtu.be/YQuu0PKoack

 

cheers

-andy crosby

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I think I have to clarify my intention of starting this thread.

 

Basically my impression is that after the new Win7 and FSX Setup on a new rig take-off runs

with PMDG 777 seems to last longer until reaching V1 than before. That means it consumes more runway

length and the feeling how the aircraft increases speed is different as before.

 

In comparison of avaiable engine power (GE90) it seems to be mismatch.

Even I have 80% of MTW or 60-70% MTW. On all airports in all weather conditions.

 

To give some more Information. I use PFPX for planing, TOPCAT for Takeoff calculation, ASN for weather, Aivlasoft EFB for inflight support

WOAI for traffic.

 

Btw assumed temp calc is a standard procedure and based on company rules to do or not to do.

 

It can be possible that my Impression is wrong so thank you Andy showing a similar run with compareable values.

I will procede some more flights in order to record the time to reach V1. May it give me a better basis to analyze and compare.

 

Thank you for your comments 

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First of all, don't hold the brakes until TO thrust is reached because if you do that in real life there's a high chance that the engine would surge/stall. We had two occasions where the pilots stalled the engines twice while doing static run up on the Rwy in winter time, he put the thrust too high couple with some cross wind, the result was a loud bang. Try to do a rolling Taking off which is a prefer method to begin a TO roll.

 

I don't notice the TO roll is of any significant difference from real life performance of the airplane at least on the 300ER. The whole purpose of de rate TO is to trade off surplus runway distance in order to save the life of the engine. If you would like to minimize ground roll, try to do a F20 performance calculation. this should give you a lower V1 and higher To thrust setting.

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Reading the list of addons and the procedures the OP uses I think there must be something wrong at a different point.

If the overlong T/O rolls began after a new rig installation maybe a hardware setup flaw causes the T7 not to accelerate as it should.

Probably "someone is standing slightly on the breaks" or spoilers are deployed unintentionally?

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Probably "someone is standing slightly on the breaks"

 

I have noticed on my rig that if I just touch slightly the pedal toes, there is a slight braking effect event though the brake message is not displayed in the fsx window.

A wrong calibration of the pedals or a lack of deadzone could be the cause of a longer takeoff roll.

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I think I have to clarify my intention of starting this thread.

 

Basically my impression is that after the new Win7 and FSX Setup on a new rig take-off runs

with PMDG 777 seems to last longer until reaching V1 than before. That means it consumes more runway

length and the feeling how the aircraft increases speed is different as before.

 

In comparison of avaiable engine power (GE90) it seems to be mismatch.

Even I have 80% of MTW or 60-70% MTW. On all airports in all weather conditions.

 

To give some more Information. I use PFPX for planing, TOPCAT for Takeoff calculation, ASN for weather, Aivlasoft EFB for inflight support

WOAI for traffic.

 

Btw assumed temp calc is a standard procedure and based on company rules to do or not to do.

 

It can be possible that my Impression is wrong so thank you Andy showing a similar run with compareable values.

I will procede some more flights in order to record the time to reach V1. May it give me a better basis to analyze and compare.

 

Thank you for your comments

This may simply be a false impression. It's surprising how close you get to the end of a runway at V1 at high weights and with derated thrust. Before assuming you have a problem try rejecting the takeoff just before V1. You should find you stop in time. It's amazing how effective the 777 brakes, spoilers and reverse thrust can be.

Remember the 777 performance data in TOPCAT is beta and isn't necessarily accurate.

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