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747-400 Take-off Performance Tables  
User currently offlineB737200 From Malta, joined Feb 2005, 225 posts, RR: 2
Posted (3 years 7 months 2 days 3 hours ago) and read 7883 times:

Do any of you know where I can find the take-off Performance tables for the 747-400? By take-off performance tables I mean those tables with the V1, Vr and V2 speeds at different take-off weights.

Now for the caveat, I found the tables as published by PMDG for their Flight Simulator addon. The problem is that I need them for my dissertation, so if I can get them from a more "official" source it would be better, hence this post.

Thanks in advance, I've looked around on the internet but to no avail, maybe I'll have more luck here.


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7 replies: All unread, jump to last
 
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (3 years 7 months 2 days 2 hours ago) and read 7860 times:

Quoting B737200 (Thread starter):
Do any of you know where I can find the take-off Performance tables for the 747-400? By take-off performance tables I mean those tables with the V1, Vr and V2 speeds at different take-off weights.

There is no such table. V1/Vr/V2 speeds are a function of: field length, elevation, atmospheric pressure, temperature, runway condition (dry, wet, etc.), thrust selection, flap setting, wind, obstacle clearance, anti-ice & bleed selection, and improved climb selections.

It's a very complicated multi variable function. About the best you can get is a V1/Vr/V2 chart for a specific airport/thrust/flap combination that you then have to correct for all the other variables.

Tom.


User currently offlinefrancoflier From France, joined Oct 2001, 3807 posts, RR: 11
Reply 2, posted (3 years 7 months 2 days 2 hours ago) and read 7852 times:

The closest I've seen to tables like that are backup take off perf figures to be used in case of ACARS RTOW failure. They are extremely simplified with many fixed variables, entail the use of max rated TO thrust and are valid for several different airports.

The only variables are approximated field lenght, OAT, wind and actual take off weight.

Greatly inefficient, only used as last resort.



Looks like I picked the wrong week to quit posting...
User currently offlineB737200 From Malta, joined Feb 2005, 225 posts, RR: 2
Reply 3, posted (3 years 7 months 1 day 18 hours ago) and read 7740 times:

Quoting francoflier (Reply 2):
The closest I've seen to tables like that are backup take off perf figures to be used in case of ACARS RTOW failure.
Quoting tdscanuck (Reply 1):
About the best you can get is a V1/Vr/V2 chart for a specific airport/thrust/flap combination that you then have to correct for all the other variables.

Something like that would suffice, I just need a ballpark figure for Vr at a given TOW. A more detailed calculation isn't really needed because I am using it just as a quick check of my Gas turbine model and a "look what happens when it gets hot" exercise.

Using some runway requirements charts I found on Boeing's website I need them for a standard day (15 Celsius and something like the standard day +17 degrees Celsius). Now I assumed that Vr isn't going to change too much under that 17.2 degree change. Again I need to stress that this a simplified calculation, in fact I am neglecting the onset of drag during the take-off roll. However working out the runway lengths required using PMDG's table I came up with a pretty good match of needed runway length, for my purposes it is good enough.

Thanks again and sorry for being vague, I was a bit sleepy when typing out my first post.



Lady Guinness is ready to fly...
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 4, posted (3 years 7 months 1 day 18 hours ago) and read 7736 times:

Quoting B737200 (Reply 3):
Something like that would suffice, I just need a ballpark figure for Vr at a given TOW.

I can do the calculation...just tell me what TOW and thrust you need and I can tell you what assumptions I had to make to get an answer.

Tom.


User currently offlineB737200 From Malta, joined Feb 2005, 225 posts, RR: 2
Reply 5, posted (3 years 7 months 1 day 18 hours ago) and read 7728 times:

Quoting tdscanuck (Reply 4):
I can do the calculation...just tell me what TOW and thrust you need and I can tell you what assumptions I had to make to get an answer

Wow thanks.

Ok so my initial calculations were for a take-off weight of 800 000 Lbs so we are basically at nearly MTOW. At sea level and initially at a temperature of 15 degrees Celsius and then 32 degrees. Always using a pressure of 101300 Pa. Flaps set to 10. Now using some certification documents for the GE CF6-80CB I am using a thrust of 249000 N.

If its a problem don't worry I assume it is somewhat complicated, wouldn't you need the lift coefficient of the 747's wing? If you prefer I can try work it out, just let me know what your basic plan is because as I said the only way I can think of requires the lift coefficient.

Thanks again.



Lady Guinness is ready to fly...
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 6, posted (3 years 7 months 1 day 17 hours ago) and read 7718 times:

Quoting B737200 (Reply 5):
Ok so my initial calculations were for a take-off weight of 800 000 Lbs so we are basically at nearly MTOW. At sea level and initially at a temperature of 15 degrees Celsius and then 32 degrees. Always using a pressure of 101300 Pa. Flaps set to 10. Now using some certification documents for the GE CF6-80CB I am using a thrust of 249000 N.

Vr @ 15C: 168kt (N1 104.8)
Vr @ 32C: 168kt (N1 107.8)

It's exactly the same speed because you haven't hit the point where this engine can't make full rated thrust yet (needs to be hotter or higher or both). This is a balanced field calculation, so your engine-inop-go, accel-stop, and all-engine-go distances are all about the same (~9500').

In addition to your requirements above, I used the following additional assumptions:
Runway: PHKO 17 (nice long runway so not length limited, almost exactly sea level, no obstacles)
Surface: Dry
Wind: 0/0
Obstacles: Ignore (don't screw with the climb-out to clear particular obstacles, although at PHKO that's not really important)
Packs/Anti-Ice: None (equivalent to your assumption of full thrust)
Improved Climb: None (doesn't take credit for any unused runway)

Quoting B737200 (Reply 5):
If its a problem don't worry I assume it is somewhat complicated, wouldn't you need the lift coefficient of the 747's wing?

Yes, if you're doing it from first principles. However, in this case, I'm "cheating"...I just ran the numbers using the EFB performance software that a flight crew would use, so I don't have to get down to that level of detail.

Tom.


User currently offlineB737200 From Malta, joined Feb 2005, 225 posts, RR: 2
Reply 7, posted (3 years 7 months 1 day 17 hours ago) and read 7713 times:

Thanks a million.

Hey I know its not much but if you could send me your full name and qualifications I could put you in the acknowledgments section of my write-up. You can email me through my profile page.



Lady Guinness is ready to fly...
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