Need Some Help With a Project

[Dan Webb]

Hi,

I'm currently a high school senior, and I'm required to write a relatively short research paper (3-5 pages). This year I'm looking at the possible runway extension at PVD (last year I wrote about the Southwest effect there). The paper will probably end up a lot longer than it has to be, but hey, it's a topic I love.

Anyways, one topic I want to look at is the actual takeoff runs for some aircraft, most likely the 762/763. I found this page on Boeing's site, which is pretty helpful, but does leave some questions unanswered, especially the graphs of takeoff runway length requirements. First, I have to guess the runway length needed since only a graph is given. Second, when the graph indicates the runway length required, does that just mean the length needed to hit V[sub]R[/sub]? Third, is there any way I can calculate the fuel needed for a route (e.g. PVD-LAX) with certain weather conditions? I guess I could just use MTOW.

Anyways I'm guessing I need a reference manual or something similar to make all these calculations, and I'm striking out online. Can anyone here help me out?

Thanks in advance.

 

[Dan Webb]

Bump?

 

[delldude]

Bump?

Dan,

First....most runways(for heavy aircraft) are 12000 foot and are alternates for the space shuttle.Back some years the Fed granted monies for runway extensions specifically for this purpose.
I'd recommend a fellow on these boards known as Boeing Boy as he's quite knowledgeable in these areas.
I'll PM him and hopefully he'll help you out.

 

[BoeingBoy]

Hi Dan,

Don't know if I can be of much help with your specific questions since I never flew the 767....

It sounds like you need pretty specific info on operating from PVD to specific destinations, or at least for a given range. That's where getting the required fuel would come in. And that's where I can't help.

As I'm sure you know, the runway length requirement depends on weight - you could operate a 747 or A380 from the current long runway at PVD (assuming the load bearing capability was adequate) but just couldn't go as far as the airplane is capable of going.

What you may be able to do is use a combination of Boeing charts to get some approximations. In section 2 of the 767 detail specs are "standard" empty weights for the various models (it's also shown in the payload/range charts in section 3). You can then use the payload/range charts in section 3 to come up with a take-off weight for whatever range you're looking at (don't forget alternate fuel - standard domestic reserve fuel is included). That would give you T/O weight including passenger/baggage/fuel. Then you can take that weight to the T/O runway length charts to see how much runway you'd need.

For example, if you wanted 3,000 nm range (should be plenty to cover a transcon with alternate) with a full passenger load on a 767-200ER, chart 3.2.2 says you'd take off at 301,000 lb. Taking that to the runway length chart (3.3.1) shows that you'd need about 5,000 feet of runway.

On the other hand, if you wanted to go 5,000 nm (Europe, South America) you'd need a takeoff weight of about 355,000 lb and a runway length of about 7,600 or so ft.

Jim

 

[Dan Webb]

Thanks to both of you guys for your help!

I have a couple of questions for you, Jim, if you don't mind. Let me explain my confusion a bit more.

First I have a question on the range chart (the one below is for the 752, sorry I cut off the footer). I have no problem finding the range needed for a flight, but my one question is how headwinds are factored in. Is it possible for someone like myself to calculate how much extra fuel is needed? I'm leaning towards using MTOW I think just to make it easier.

Now here's the takeoff distance chart. First, what do they mean by takeoff distance? Do they mean how far it takes to hit V[sub]R[/sub]? My other issue is that I can't get an exact number, I have to guess. So I'm trying to see if there's a more exact method.

Now my other question comes from some more research. I was looking at some letters to the editor in various papers around here, and I found this.

Flying from the West Coast to Providence would not be a problem but flying nonstop from Providence to the West Coast is not possible at this current time. Here’s why: a fully loaded Boeing 737-700 with winglets (devices on the wingtips that help an aircraft fly farther on less fuel) needs 6,800 feet of runway at 27°F and a flap setting of 25 to takeoff (Temperature directly impacts takeoff distance – the hotter the temperature, the more runway needed. That 6,800 feet would only grow during the summer). This is the aircraft that Southwest would use on coast-to-coast flights (as I’ve pointed out before, Southwest would be the first carrier to offer coast-to-coast flights). Rotation would occur at about the 6,600-foot mark and on Green’s runway, this leaves about 600 feet to establish a positive rate of climb. After establishing a positive rate of climb, the aircraft may hit a few landing lights, dubbing it unsafe to operate at a full load (in the summer, this may not be too far out of the picture).

Original Article

I found this very interesting because I checked the Boeing takeoff chart for the 737-700W and saw this:

And that looks a lot less than 6,800 feet, more like 5,800. So I was wondering where he would get such numbers from.

Thanks in advance if you can clear any of this up!

All the best,

Dan

 

[BoeingBoy]

First I have a question on the range chart (the one below is for the 752, sorry I cut off the footer). I have no problem finding the range needed for a flight, but my one question is how headwinds are factored in. Is it possible for someone like myself to calculate how much extra fuel is needed? I'm leaning towards using MTOW I think just to make it easier.

The headwind/tailwind issue is a tough one - I don't have any average figure you could use, although I'm sure someone somewhere has the answer.

Now here's the takeoff distance chart. First, what do they mean by takeoff distance? Do they mean how far it takes to hit V[sub]R[/sub]? My other issue is that I can't get an exact number, I have to guess. So I'm trying to see if there's a more exact method.

If I remember correctly, somewhere in there Boeing says that the chart gives FAA required runway for T/O so I assume that it has the required safety margins built in. As for getting an exact number, all I could suggest (short of finding someone in an airline's dispatch office to run the figures for you) is to print out the chart as large as possible to make interpolation easier.

Now my other question comes from some more research. I was looking at some letters to the editor in various papers around here, and I found this.

I see what you say about the difference. Don't have any idea where the person that wrote that got their info, but Boeing's chart should be accurate for the conditions listed (and assuming that "FAA required runway means what I think it means). There may be something concerning obstacles at PVD that would affect the distance, but I don't remember anything particular going in or out of there. Of course, the Boeing data is best case - dry runway, 59 degrees, etc. Again, the only way to get exact numbers would be to have a dispatcher run the numbers thru the computer.

Another possibility, just for the 737-700, is if you could get someone from the Southwest forum to run the data thru their laptop - they have one in each airplane for performance calculations.

If all else fails, a note to the effect that all your performance data comes from the Boeing charts would probably suffice for your purposes.

Jim