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Tristar L-1011 FMS & Autopilot

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Tristar L-1011 FMS & Autopilot

Old 21st May 2009, 16:06
  #101 (permalink)  
 
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My point entirely, lockheed had to install it to make it land safely, if it was so good why didn't Boeing copy it?
I suspect Boeing simply did not have the technical expertise to do so.
In fact, speaking of technical expertise, my local airport neighbor, who parks his GA airplane next to mine, is a retired Boeing design engineer.
His exact words, from a conversation about a month ago...."When we first got a close look at the systems and avionics integration on the L1011, it was a huge wake up call for those of us in Seattle, Lockheed was years ahead of anything we even had on the drawing board."

And, so it goes...someone had to be first.
Lockheed most certainly was, without a doubt.
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Old 21st May 2009, 16:07
  #102 (permalink)  
 
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Lockheed has always built stiff winged airplanes. Witness the failures on C-130s and C-5s. The stiff wing is more efficient, but has to be far more rugged, and gives you a rougher ride. Douglas built a moderately stiff wing, and when you watch the swinging outboard engines on a 747, you wonder how they ever calculated angle of attack.

Nobody has mentioned Active Controls, computers that allowed the -500 to add more span without beefing up the wing.

As I mentioned early on in this thread, the DC-10 and 747 had sheet lead blankets to deaden the buzz saw sound on takeoff. I was told the 727 also had sheet lead in the sidewalls, until the fuel crisis of 1973. There is no better sound deadener.

GB
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Old 21st May 2009, 16:07
  #103 (permalink)  
 
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It was so stable and smooth that I think that the crew of a well known charter carrier out of Gatwick found it so smooth that they fell asleep on the approach into a Greek Island, forgot to flare, broke the rear pressure bulkhead and another of Lockheeed's finest had to be dispatched to the bone yards of Arizona.
Sorry 411A not my favourite plane, but please do not take it personally
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Old 21st May 2009, 16:25
  #104 (permalink)  
 
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Douglas built a moderately stiff wing....

....which seems to snap off at the root occasionally on MD-11 types.
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Old 21st May 2009, 19:23
  #105 (permalink)  
 
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It was so stable and smooth that I think that the crew of a well known charter carrier out of Gatwick found it so smooth that they fell asleep on the approach into a Greek Island, forgot to flare, broke the rear pressure bulkhead and another of Lockheeed's finest had to be dispatched to the bone yards of Arizona.
Thank you for the complement, as I was the Lockheed representative on site.
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Old 4th Mar 2010, 09:39
  #106 (permalink)  
 
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I am quite interesting in L-1011 AP as it seems to have been a pioneer of Cat3.
I have seen Flare, Align, Roll-out and aproach lights on pilots' main instrument panel but I haven't seen any push-button to engage the autoland mode. How was-it managed ?
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Old 4th Mar 2010, 19:25
  #107 (permalink)  
 
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AS a Avionics engineer on L1011s with British Airways I must protest at the claim Lockheeds pioneered Cat 3 landings I also worked on the DH121 Trident which was doing Cat3b landings way back in the early 70s long before we had our Tristars, Smiths Autopilot division pioneered automatic landings way back in the 50/60s and the Trident was built with that system in mind Triple Hydralics, Triple none parallel electrical sytems as demanded by the C.A.A at the time and a host of safety measures including multi system reading flight data recording .I admit the L1011 system was better in the end but it had [email protected] gyros and other better electronics which were not available to the Trident as they were in their infancy nor developed at the time the Smiths system was conceived.
As for engaging the auto land system on the Tristar you normally flew with either "A" or "B" autopilot engaged the other had to engaged as well but I,m afraid the routine after that has become a "Senior Moment" and I can't remember the sequence after , I can remember the test set transmitted a glide slope signal and the height was decreased until we got it to land this had to be done slowly or the horizontal stabilzer used to move too much and the nose would oscillate trying to follow the gyro system.

Last edited by avionic type; 4th Mar 2010 at 19:58.
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Old 4th Mar 2010, 21:43
  #108 (permalink)  
 
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Please forgive my mistake and misunderstanding. As I am almost young I am more aware of recent aircraft. I have recently begun to study oldest aircraft like VC10, Trident or Tristar, knowing they are all capable of autoland.
When I have talk of pioneer in fact I was thinking of fail-operational digital autopilot of L1011.

in addition of engagement of autoland mode, I was also wondering how
pilots were informed of selected Decision Height.
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Old 5th Mar 2010, 01:24
  #109 (permalink)  
 
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When I have talk of pioneer in fact I was thinking of fail-operational digital autopilot of L1011.
In actual fact, only the last few L1011's manufactured had digital autopilots, all the rest were dual channel fail-operational analogue design.

Sequence for automatic approach/land (autoland) with the L1011.
Only one autopilot is engaged for maneuvering, in heading mode, approaching the final approach course.
On that final intercept heading, the A/L switchlight is depressed, and at this time, the second autopilot is engaged.
The aircraft intercepts the final approach course, and continues inbound.
At 1500 feet agl or 25 seconds after glidepath interception, automatic approach land track is established.
The autopilot rudder channel reverts to parallel operation (rudder pedals move in response to autopilot inputs), and when flaps are selected to the landing flaps position, direct lift control (DLC) becomes operational.
During the final approach segment, a series of voting circuits constantly monitors all four autopilot channels, and will reject a faulty signal from one...or two.
In this case, a 'no dual' message appears, and the approach is continued to category two minima.
At 150 feet radio height, runway alignment begins.
At 50 feet radio height, the auto flare maneuver begins.
At 5 feet radio height, autothrust is disconnected.
Upon touchdown, autospoilers are actuated, and the airplane continues to track the localizer...right down the runway centerline.

In over 800 autolands with the L1011, I have only had to discontinue one...and that was due to a localizer transmitter ground failure.

L1011, a truly remarkable, reliable airplane, for autoland operations.

in addition of engagement of autoland mode, I was also wondering how pilots were informed of selected Decision Height.
With category three operations, there is no decision height, only an alert height.
For category two autoland operations, the L1011 uses a decision height via the dual radio altimeters.
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Old 5th Mar 2010, 03:12
  #110 (permalink)  
 
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411A I think that your systems knowledge for the type is extremely sparse

PA
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Old 5th Mar 2010, 04:43
  #111 (permalink)  
 
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The original L-1011 Autoland system was a joint effort by Collins and Lear-Siegler. The L-1011-500 had the digital Autoland by Collins. I don't know if there were any later non-500 with the digital autoland.

GB
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Old 5th Mar 2010, 20:27
  #112 (permalink)  
 
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I don't know if there were any later non-500 with the digital autoland.
Threre were not.

Additionally, if one watches very closely, with -22B powered airplanes, a slight thrust increase from the autothrottles is noted, at 30 feet radio height, just prior to thrust reduction.
This is to provide...the smooooth touchdown...that the L1011 is noted for.
With -524B4 engines, not needed.

L1011...in a class of its own, yes...old now, but still the gold standard to which others are compared...even today.
Dual/dual, fail operational.

A truly fine pilots airplane
In this latter case...just like the Electra.
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Old 6th Mar 2010, 18:06
  #113 (permalink)  
 
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Hi 411A,

In this case, a 'no dual' message appears, and the approach is continued to category two minima.
I think that's an FAA regulation which didn't recognise the "double dual" redundancy in the Autopilot A/L system. The UK CAA permitted us to revert to CAT III single limits of 50 radio & 200m RVR with a "DANA" warning. PFM.

Interestingly - in the early days - it was only the UK which permitted us to use CAT IIIB NO DH, 75 m RVR limits. France etc. insisted we use CAT IIIB with 15 ft DH limit & 75m RVR (required a runway centre line light or marking to be visible). I believe this "mini DH" is coming back in again for low vis ops in France.
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Old 6th Mar 2010, 20:23
  #114 (permalink)  
 
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PFM.
Indeed, PFM...must be seen, first hand, to be believed.

And, just think...forty years old, this year.
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Old 7th Mar 2010, 00:22
  #115 (permalink)  
 
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From a retar'd TWA Capt:

Lawren wrote:

In a 31 year career I only made 2 or 3 Cat III approaches (L1011) which was enough. It's a full automatic landing so the pilot is just along for the ride until after the aircraft is on the runway.
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Old 7th Mar 2010, 09:52
  #116 (permalink)  
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In this latter case...just like the Electra

Salut, good sir !
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Old 7th Mar 2010, 13:35
  #117 (permalink)  
 
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Well having worked on several for a few years, I can still say she was the best.

So much so that when I visit Kavala, Greece, I struggle to complete the checklist or write the techlog as I stare in utter delight at such magnificent lines and memories to boot.

Why oh why is a lovely 200 sat in Kavala having been dumped there. It is such a waste. Those RB211's are just spinning in the wind without a care in the world....

411A can you come and rescue her??
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Old 7th Mar 2010, 14:30
  #118 (permalink)  
 
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I recall about 7-8 years ago walking among parked L-1011's in Taif, about 10-15 of them, the engines clacking away in the wind; maybe a year ago 2 or 3 workers were assigned to start dismantling one of them (they had been stored there since...1995 or so?). They cut into a wing, and started a fire which killed them. No one had thought to check if they had been de-fueled after being parked, which they hadn't. They weren't preserved or stripped, just taxied into parking and abandoned, and they sit like that to this day!
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Old 7th Mar 2010, 14:44
  #119 (permalink)  
 
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411A can you come and rescue her??
Oddly enough, our small consulting/management company has been asked to look into...this very thing.
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Old 7th Mar 2010, 15:37
  #120 (permalink)  
 
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Oh great - maybe I shall see her gear doors raised once again. There is still pressure in the tyres too.

I have pictures taken today if they are of interest....

And I can get more close ups if you need.
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