aa61hvy
Topic Author
Posts: 13021
Joined: Fri Nov 05, 1999 9:21 am

### Need Help On A School Project

For my math course, we were given an open project to do any math related thing we can think of, and explain it and solved it etc..

I chose to do the relationship between the airplanes weight (with engine thrust also) in relation to the amount of runway it will need to take off. The plane I think I may do is a 777-200 with Rolls Royce engines. But if someone has a lot of information on another place then I will change it. But only commercial planes.

Basically: I need some info on how pilots determine the amount of runway for their plane. I need solid sources, and definite answers.
Thanks a lot!

Also, if what I wrote is confusing, then let me know, and I will re-write it. Or any questions email me, or post them. Thanks
Go big or go home

jhooper
Posts: 5561
Joined: Thu Dec 13, 2001 8:27 pm

### RE: Need Help On A School Project

Basically, all I do is just look up the data in the FAA Approved Airplane Flight Manual for the aircraft I am flying. There is a performance chart where you can look up your pressure altitude on the Y-Axis and the temperature on the X-Axis, and the intersection of the two values gives you the amount of runway required for that plane at a given weight. I really can't get into the mathematical formulas used to compute this data, because I just don't know. Many professional pilots flying modern equipment have sophisticated computers to compute this data for them.
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744rules
Posts: 391
Joined: Sat Mar 30, 2002 3:34 am

### RE: Need Help On A School Project

Most airlines have tables that work the other way around. They compute the max weight they can take on a known runway, adjusted with factor such as windspeed/-velocity, pressure, surface dry/wet/snowcovered,...

good luck with your task

aa61hvy
Topic Author
Posts: 13021
Joined: Fri Nov 05, 1999 9:21 am

### RE: Need Help On A School Project

I thought I would add this for more clarification: maybe a formula to calculate the rwy length and airplane weight, also it would be generic weather 70 degrees F, at 0 feet.
Go big or go home

Woodreau
Posts: 1421
Joined: Mon Sep 24, 2001 6:44 am

### RE: Need Help On A School Project

Try here....

http://www.boeing.com/assocproducts/aircompat/777.htm

Chapter 3 has the airplane performance info. It's not tailored to each individual aircraft, but is a general table for a 777. Towards the end of the chapter are the FAR Runway takeoff lengths and landing lengths.

A standard day is 29.92, 59 deg F, at sea level.

Start at the bottom of the chart with the takeoff weight. Go up until you reach the pressure altitude, then go left to find the runway length. Some of the pressure altitude lines have notches where you go from Flaps 20, to Flaps 10, etc...

You need to find the chart for the appropriate engine and the appropriate temperature.

For example: using table 3.3.7 with a 777-300 with 98K thrust engine on a standard atmosphere day at sea level with no wind and no runway gradient, air conditioning packs off, with a gross takeoff weight of 620000lb with flaps 20 you should have a takeoff length of 9200ft.

Hope this info helps.

Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.

aa61hvy
Topic Author
Posts: 13021
Joined: Fri Nov 05, 1999 9:21 am

### RE: Need Help On A School Project

Woodreau- you just summed up my whole paper there!! thanks ALOT!!! I plan on writing basically what you said, but I am going to BS it pretty bad, so it will take up more room, luckily my teacher does not know anything about planes!
Go big or go home

jhooper
Posts: 5561
Joined: Thu Dec 13, 2001 8:27 pm

### RE: Need Help On A School Project

I thought I would add this for more clarification: maybe a formula to calculate the rwy length and airplane weight, also it would be generic weather 70 degrees F, at 0 feet.

You wouldn't need to "calculate" the runway length, because it's already a known value. To get the aircraft weight, simply refer to the weight and balance information for that aircraft. For example, it will give you a basic empty weight, to which you can add the weight of the pax, cargo, fuel, etc., to arrive at the gross weight.
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