L-1011-500 RNWY performance querry
I know she's an old design now, but I am curious to find out the runway performance of an L-1011-500 from a 6,450ft runway. Rather, the gross take off weight possible from sea level, on a standard day. Are there any PDF graphs available online anywhere ?
Failing that, are there any greybeards out there who could help me please ? |
well before the 767-400 became the largest gal outta LGA TORA = ASDA=7000'
Ive seen L-1011's [not sure which model] DC-10's and maybe IIRC an MD11 depart and have a little to spare:) |
Well, lets see...
6,450 feet, std day, sea level, no wind, full thrust, flaps 22... 461,000 pounds (approximately). This presumes no obstacles present, so using flaps 22 is possible, to shorten the take off distance required, to fit the shorter runway. The -500 model is a VERY good performer, both going and if need be, stopping. Greatly improved brakes. |
...but only with the FAA or JAA certification. A UK CAA certified L1011-500 wouldn't get airborne from 6450ft at any useable mass, it would be Vmcg limited.
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Really?
Seems strange to me. At light weights, Vmcg is down around 131 knots or so, IIRC. The speed comes up mightly quickly in the -500. Now, having said this, I haven't operated the aeroplane to CAA performance limitations, so you could be right. Cambridge (Marshals) is about this length, as I recall, and I've operated from there direct to North America, flap 22, with a 10 knot headwind for departure, no pax of course. Now, if we look at the takeoff weight limitation, and the runway required... Runway 11,000 feet, sea level, 25C. No obstacles Flap 14 Max weight, 510,000 pounds, which is also the max structural allowed. Takeoff distance required, 10,700 feet. Using flap 22 (which was not commonly used), the distance required is less, of course |
411A is right about the L-1011-500 performances :ok:
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Ah, I never learn. I was shooting from the hip, remembering the RAF TriStars couldn't really get out of anything much less than 8500ft with a useful load, even when using a Vmcg derived from the 22B thrust figures. I'll try and find some graphs to check it properly.
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Alex I think you're absolutely right! The -500 was awfully Vmcg limited especially when operating to CAA limits (ie 7 knots x-wind used for calculating Vmcg). By reducing thrust to -22B values on short runways we were able to lift something like 20T more cos we weren't eating up runway trying to get to a V1 that was higher than Vmcg!!
I suspect that even using FAA figures there would not be much payload available at all on 6500' with meaningful fuel. Happy to be proved wrong tho! |
A UK CAA certified L1011-500 wouldn't get airborne from 6450ft at any useable mass, it would be Vmcg limited.
...So how did all the UK CAA certified former BA L10s [and today's BA 74s] get into and out of Cambridge [CBG/EGSC, 1965m, 6447']...? :confused: |
Getting in is not a problem but the L1011 at least didn't get out at any useable mass. We didn't need much mass because we only went into Cambridge to ferry the aircraft to and from Brize. I suspect the 747 doesn't have the same VMCG issue as the -500.
Unfortunately the only UK L1011 performance data I have left is for the -1 so I can't back up my memory with an RTOT, maybe someone still on 216 could check it out? |
Originally Posted by GlueBall
So how did all the UK CAA certified former BA L10s [and today's BA 74s] get into and out of Cambridge [CBG/EGSC, 1965m, 6447']...? :confused:
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Many moons ago when I was at CBG we were not authorized to taxi, but had to get towed off the runway, ...I presume that the taxiways had since been widened.
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I have a several old L-1011 sales brochures with takeoff charts, while these charts may or may not be correct I would think they are close.
For the -500 the chart shows a MTOW for a 6450 foot runway to be 428,500 lbs. For a -1 the chart shows a MTOW of 380,000 lbs. As I said these charts may be way off or spot on I don't know. I do know we took an Air Transat -150 out of Lemwerder, Germany and the runway there is only 6234 feet (20 ft elevation). I don't know how much fuel we had on board, probably not much, but we made it to Stansted. |
Caution: Thread Creep
BTW, in the USAF (C-5) we calculated Vmcg and accounted for crosswind, about 1kt increase per knot of crosswind. Why does it seem to me that the FAA does not do so? And the CAA uses a nominal 7 knot crosswind! Crosswind has a significant effect on Vmcg On the Global Express, Vmcg is 88 knots and no correction for crosswind. At light weights, V1 is based on Vmcg and with a strong crosswind might, in fact, have a V1 less than Vmcg--NOT GOOD! GF |
Galaxy Flyer,
.. which is why you see Mutt and me regularly revisiting Vmcg considerations in this forum for the benefit of the newer folk coming along. Concur with your observations... For civil certification, Vmcg is a "line in the sand" issue rather than just another tactical calculation to be done as in your operation ... your observation about lightweight departures in strong crosswinds is our particular concern .. quite common in the airline short distance positioning game. As a sideline observation, the variation itself varies with Type but 0.5kt/kt for twins increasing to something in excess of 1kt/kt for four motored beasties is reasonably typical .. Numerous old threads have things to say on the topic .. |
What is Vmcg?
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DAL2728, minimum control speed on the ground = VMCG, but I am kind of at a loss how that relates ?
Still thank you very much all of you... Didn't mean to stirr a hornet's nest. Seems like one does have to go to a museum, or likewise to find these charts nowadays. |
Kiwi,
Just tried to post a long reply only to find that the system dumped it! Here goes in quick time. Because the -500 has a shortened rear fuselage the rudder is less effective. On a short runway we have to accelerate the a/c to V1 before we get it airborne. However because of high Vmcg, V1 also has to be high and therefore we have to severely limit the weight to enable a very quick acceleration to V1/Vmcg. By reducing the thrust we dramatically reduce the Vmcg and thus lower V1 as well. Lower V1 means an increased ability to stop from higher weights and so with less thrust we can lift higher weight off a short runway. Easy huh? Lockheed themselves realised the problem and developed a fix for airlines who regularly operated out of short strips. BWIA used this mod in the Carribbean which was a fibreglass rudder extension that restored the effectiveness of the rudder. The short rear fuselage brought with it many other problems that Lockheed had to address. Some were dynamic high speed gust alleviation (the first of it's kind I believe), over pitching with go-around thrust application and others. Great machine though! |
Seems like one does have to go to a museum, or likewise to find these charts nowadays. Mutt |
Mutt, you don't work for ATA do you? I flew on an ATA L-1011-500 not two years ago. Ride of my life.
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