An-124, C-17, B747 LCNs?

[Tragic Rug]

Hi,


I would be really grateful if anyone out there has details on the AN-124-100 payload-range charts, ACN/PCN and runway length (take-off and landing)/weight charts.

I hope someone can help.

Regards,

Tragic Rug

[OverRun]

The ACN/PCN charts are here (http://www.geocities.com/profemery/aviation/124.htm).

It took me all today to get that ACN answer and check it (although most of that was spent on other aircraft as my work widened).

Typical of responding to something technical on PPRUNE, as one thing led to another. Not an entirely wasted day, playing with designs to get ACNs. I found a significant error in one major ACN/pavement design program, and another significant error in the ACN chart in the ops manual of another aircraft type (which gives a major improvement for the aircraft and makes the economics considerably better) [all obviously nameless] That in turn will spin off into another day's engineering work for the engineers involved with the program to fix it, and a couple of days work for the aircraft manufacturer. I'll end with a better program, and I reckon the aircraft manufacturer owes me a case of cold beer.

Not bad for what seemed like a simple PPRUNE Tech Log question :ok:

[OverRun]

Tragic Rug,

In your original post (before your editing) you said that you were doing a dissertation. What level and what degree? Post-grad? And what weight/hours have been given to this dissertation? Is it equivalent to a one semester subject or what?

You can construct your own payload range and takeoff length charts for the aircraft, to a reasonable standard. Not for operations, but sufficient for a dissertation. Based on the data from Jane's, and some fundamentals of aircraft operation. And this sort of construction from fundamental principles is often a required part of any dissertation.

[Tragic Rug]

OverRun,

I am doing a dissertation for MSc level. I understand your point regarding constructing my own take-off and landing runway requirements, however this is not an engineering MSc and I don't think I have the background knowledge. The dissertation is worth 1/3 of the overall marks given for the course.

I am trying to find out the An-124-100 detail in order to build up a picture of runway length requirements depending on load carried etc. Ultimately I am trying to compare the commercial viability of the BC-17X with the An-124-100. Runway length requirements is one of the areas I thought would be worth a look.

Many thanks,

TRagic Rug

[OverRun]

Tragic Rug,

I’m sure you have realised by now that the “Prof” part of my nickname stands for Professor rather than Professional, and hence my questions. At the MSc level, and with the dissertation being worth 1/3 of the overall marks given for the course, the implication is that you are able to spend some time and effort on the dissertation.

The payload/range graph you should be able to build yourself, and it is probably an integral part of your dissertation anyway. If you are comparing aircraft economics, then you’ll need to have constructed your own spreadsheet model of weights, loads, fuel burn, etc so as to do your dissertation. For the An124, Janes will give you the starting data.

There are a couple of techniques I can share with you. The first is to create a model for another aircraft on which the data is freely available. For no reason other than I spent this weekend frantically rebuilding the models for the 737-800 economics for my work, can I suggest you build the model for that aircraft. I am happy to help you as you do that, and I suggest we do it publicly through Tech Log as part of a contribution to knowledge. Starting points are weights and fuel burn. Ending point is, well say, the takeoff weight to haul 140 pax and 300 dozen beers from Perth to Broome in bad weather.

Once you have built the model for an aircraft that can be verified, you will find that modelling the An124 (and the BC17) will be child’s play.

The second technique is what I (and fellow kubuer EH) have used very successfully in our professional work. And that is to start at the end and work back. For the runway length graph, if you don’t have one, than use one from another similar aircraft and do your work based on that. You will eventually get something for the An124 and then need only adjust figures slightly in your models. So think through what aircraft is not-too dissimilar and for which data is available, then tell us what you’ll choose.

[Tragic Rug]

OverRun,

I'm happy to try and build the model you suggest and I am even happier to have some academic feedback. I'll work on something over the next few days and I will send you something via PM. If you are happy with the model I will happily post it on the open forum.

Ref ac types similar to An-124-100 the Lockheed C-5 is the obvious choice for comparitive details. Unfortunately I can't find the relevant performance data for the C-5 either. Very frustrating.

Regards,

Tragic Rug

[john_tullamarine]

I can't find the relevant performance data for the C-5 either

Galaxy Flyer doesn't these days .. but certainly did for quite a while .. you might like to send him a PM to attract his attention to this thread ..

PPRuNe is an absolutely incredible resource .. you have some of the most experienced people in their fields playing regularly in the Tech Log sandpit ..

[galaxy flyer]

John, funny you should mention me!

If you look at the LCN charts, the C-5 is pretty light on its 28 paws. It was designed to fly a radar low-level, land a tank on a dirt runway and recover to FRA out of a CAT III autoland. Exactly how it was going to land, CAT III on the dirt was never explained. I, in a fit of "I don't give a crap" attitude familiar to all ex-mil types, didn't keep a perf manual. It was almost larger than the Flight Manual. But I still have friends, if I ever get off this never-ending trip.

Anyway, TOGW, runway permitting, was 769,000 pounds. Fuel burn of about 28,000 the first hour, 24,000 for the next 4, then gradually back to 20,000 at TOD. Average about 22,000 pph over 8-10 hours. Initial level, between 280 and 310 after near TOGW take-off, step up to 350-380, 9 hours later. Temp deviation was always an important factor.

172,000 pounds of thrust for 5 minutes. Rotate was about 138 knots at 769 and V2 would be around 150-154, as I remember. But acceleration was nothing to rave about check speed at 120 knots would be around 36-40 seconds and take-off roll at Torrejon could be close to a minute and 11,500 of 4-engine run. Most take-offs were closer to 6000-7500 feet, climb limited. At Ramstein with 8600 feet and 200 ft/nm required climb gradient, gross weights of about 735,000 to 750,000 were possible in all but the hottest days-380,000 lbs BOW, 120,000 pounds payload and 225,000-240,000 pounds of fuel for destination KDOV in 9 hours. 240,000 pound payloads necessarily required lots of tech stops or air refueling, not frequent ly done. But the USN seemed to design things to max it out. Dry runway Vmcg, a Pprune fave discussion, was about 80 knots without a crosswind. It was calculated for each take-off, adjusted for wind and runway condition. One of the more remarkable numbers! CF6-80A engines will improve things by reducing required fuel loads by 15%, faster climbs to levels that will optimize the wing.

Is any of this useful?

GF

John, Is Avalon on for next year?

[john_tullamarine]

.. see what I mean ... ?

Avalon sure is on next year (http://www.airshow.net.au/).

Can't imagine that you folk won't be along to hawk your wares ...

How about we get you along to the FTSA dinner down on the water at Williamstown .. much better than a passing g'day on the flightline ? Perhaps you might even have some time to attend part of the Symposium ?

[galaxy flyer]

Yes, the folks will be there hawking our wares, but can I suck up enough to the schedulers to one of them? Days in OZ are not subtracted from one's total allotment.

Would like the invite to Williamtown very much. I'll stay in touch.

GF

[john_tullamarine]

I reckon I could try to get Prez Skates to contra a presentation on Galaxy Flying for a freebie invite .. and you get to sit on the Head Table. Site's down at the moment for whatever reason but I'll leave it here (http://www.ftsa.org.au/) if anyone's interested.

[galaxy flyer]

Been there in the mighty Galaxy a few times, the Radisson downtown was most accomodating! Take-off over the beach, impressive.

[OverRun]

Tragic Rug,

The Boeing airports data is available here (http://www.boeing.com/commercial/airports/plan_manuals.html) courtesy of those nice folks at Boeing Airport Technology.

[Tragic Rug]

Galaxy Flyer,

Thanks for the information, all useful stuff. Can you comment on the landing distance/weight performance of the C-5?

OverRun,

Many thanks, It was the Boeing website that started me on this quest originally. The C-17A/BC-17X acn/pcn charts are great open source stuff.

Regards,

Tragic Rug

[galaxy flyer]

TR

Yes, normal landing weight was 635,850 (yes, a common evaluator question) and there was only a sink rate limit on landing at max TOGW. As noted, the ACN was rather low for its mass. At 635,000, Vref would be about 135 KIAS and dry distance, using max anti-skid, about 4700 feet, around 1600 of that "flare distance" from 50 feet over the fence. I landed at about that weight at RMS once, used heavy braking but not max, and cleared at about 5000 feet from the approach end. No, I won't tell you why I tested the charts. Another time, on ice, RCR of 6, computed distance at about 560,000 was 5000 feet. Low and behold, stopped on a 7000 foot runway abeam the 2000 remaining signboard.

Hope it helps.

Add the number of thousands of pounds to 75 and that was the approximate Vref. IE, 500,000 pound plane would have a Vref of 125 KIAS. 10 Knots less would be a rough V2.