Tristar's Direct Lift Control
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Could someone explain YAW SAS and RSB (Roll Speed Brake) please.
Depending on the model, the nuetral point of the spoliers during DLC was 7 or 9 degrees, I think 9 degrees for the -500.
Depending on the model, the nuetral point of the spoliers during DLC was 7 or 9 degrees, I think 9 degrees for the -500.
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VR-HFX. The two best aircraft I ever flew were both Lockheed. The L-1011, and the L-188. Both powered hydraulic controls, both a dream to fly. Both with multiple redundancy on all major systems. Pilots dreams, engineers nightmares.
Having given the manuals away years ago, from very rusty memory.
Re: YAW SAS(stability augmentation system)
basically multiple yaw damping, and also used for runway alignment in autoland mode. I vaguely remember something about rudder fusing, but better refer to 411A -his memory is better than mine.
Roll speed brake was the multi-mode activation of the spoilers by a VERY complicated hydraulic mixing valve. Differential spoilers=roll, simultaneous spoilers =speed brake.
There was also MDLC (Mach direct lift control) which came into play above M.65 and I think from the same mixing valve.
LEM, the "difference" made by DLC was that you were not constantly jockeying attitude and throttles in gusty conditions, the attitude just stayed the same and the aircraft's rate of descent varied with stick input only. As 411A said, do not flare and then push as per Boeing, because you would just crunch the aircraft on. (sink increased dramatically!)
Having given the manuals away years ago, from very rusty memory.
Re: YAW SAS(stability augmentation system)
basically multiple yaw damping, and also used for runway alignment in autoland mode. I vaguely remember something about rudder fusing, but better refer to 411A -his memory is better than mine.
Roll speed brake was the multi-mode activation of the spoilers by a VERY complicated hydraulic mixing valve. Differential spoilers=roll, simultaneous spoilers =speed brake.
There was also MDLC (Mach direct lift control) which came into play above M.65 and I think from the same mixing valve.
LEM, the "difference" made by DLC was that you were not constantly jockeying attitude and throttles in gusty conditions, the attitude just stayed the same and the aircraft's rate of descent varied with stick input only. As 411A said, do not flare and then push as per Boeing, because you would just crunch the aircraft on. (sink increased dramatically!)
Last edited by ZQA297/30; 3rd Mar 2006 at 20:17.
Usual disclaimers apply!
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MDLC Manouvering direct lift control: improved pitch axis handling at combinations of high wt. high speed high alt. and aft C of G.
RSB Recovery speed brake an extension to the Manouvering Direct Lift Control armed when flaps up and above 2500ft??? (RAD ALT?) spoilers will deploy to 60deg when a/c above M.85 and measured G above 1.5. plus a few other combinations that I cant recall.
YAW/SAS something to do with control of duch roll???
RSB Recovery speed brake an extension to the Manouvering Direct Lift Control armed when flaps up and above 2500ft??? (RAD ALT?) spoilers will deploy to 60deg when a/c above M.85 and measured G above 1.5. plus a few other combinations that I cant recall.
YAW/SAS something to do with control of duch roll???
Jeeesus!
Now I know why my fellow engineers called it the Tri-Bastard!!
All I remember (as a young spunker) was sliding around on my @rse trying to stick a couple of qts in no.2.
Now I know why my fellow engineers called it the Tri-Bastard!!
All I remember (as a young spunker) was sliding around on my @rse trying to stick a couple of qts in no.2.
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TriStar, an oldie, but a goodie
YAW/SAS
Provided,
*turn co-ordination
*yaw damping
*runway alignment
*runway rollout control, thru rudder actuation/rudder pedal steering.
The last two during automatic approach/land operations, using one or two dual channel autopilots
In twenty five years (and still counting) on the Lockheed tri-motor, no problems experienced whatsoever with roll/speed brake, MDLC, YAW/SAS, DLC or indeed any other control function.
A very reliable aeroplane, IF maintained properly.
Oh yes, hydraulic fusing, built in at the factory, to eliminate total hydraulic system loss due to system leaks.
So, no JAL (747) or UAL (DC10) total system loss nonsense.
And, but certainly not least, the only first generation wide-body jet aeroplane not lost due to a system failure/malfunction.
In addition, the first wide body certificated to CATIIIB right out of the box, thanks to a very few ex- HS Trident/Smiths folks...
Gosh, almost forgot, thanks to Rollers, stage three from the beginning, unrestricted.
One more, full authority FMS (if ordered) which provided RNAV/VNAV and thrust management, all in one very neat package, direct from Palmdale.
Provided,
*turn co-ordination
*yaw damping
*runway alignment
*runway rollout control, thru rudder actuation/rudder pedal steering.
The last two during automatic approach/land operations, using one or two dual channel autopilots
In twenty five years (and still counting) on the Lockheed tri-motor, no problems experienced whatsoever with roll/speed brake, MDLC, YAW/SAS, DLC or indeed any other control function.
A very reliable aeroplane, IF maintained properly.
Oh yes, hydraulic fusing, built in at the factory, to eliminate total hydraulic system loss due to system leaks.
So, no JAL (747) or UAL (DC10) total system loss nonsense.
And, but certainly not least, the only first generation wide-body jet aeroplane not lost due to a system failure/malfunction.
In addition, the first wide body certificated to CATIIIB right out of the box, thanks to a very few ex- HS Trident/Smiths folks...
Gosh, almost forgot, thanks to Rollers, stage three from the beginning, unrestricted.
One more, full authority FMS (if ordered) which provided RNAV/VNAV and thrust management, all in one very neat package, direct from Palmdale.
Last edited by 411A; 4th Mar 2006 at 01:14.
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Tristar's today
Hi Guys, this may be a stupid question:
Are they many tristars in operation today, can you still get good engineers for the tristars.
Any known common faults etc.
Bit of an enthusiast....sorry
Are they many tristars in operation today, can you still get good engineers for the tristars.
Any known common faults etc.
Bit of an enthusiast....sorry
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Sigh. If only Lockheed would go back into commercial aircraft. We are overdue for a technology breakthrough. We have been up against the M.85 barrier for mass travel for over 30 years.
Surely the skunk works has at least thought about something new and revolutionary?
Surely the skunk works has at least thought about something new and revolutionary?
I've 3500 hrs on TriStars but haven't flown them since 1987.
Didn't like manual approaches with DLC because the normal clue of pitch change was much reduced. Some people would hit the TOGA (after disabling auto throttle) to disable DLC for landing to allow them to 'play the runway' but good point re the enhanced GA energy it provided.
Hydraulics weren't entirely 'unsinkable'. Crew had a tyre blow at Karachi and (thankfully) elected to stop. The debris took out three systems leaving only D. I've flown the sim on D alone and it is not a pleasant experience. (if I've got any of the detail wrong then I'm sure Tim or a member of his crew will correct me).
Didn't like manual approaches with DLC because the normal clue of pitch change was much reduced. Some people would hit the TOGA (after disabling auto throttle) to disable DLC for landing to allow them to 'play the runway' but good point re the enhanced GA energy it provided.
Hydraulics weren't entirely 'unsinkable'. Crew had a tyre blow at Karachi and (thankfully) elected to stop. The debris took out three systems leaving only D. I've flown the sim on D alone and it is not a pleasant experience. (if I've got any of the detail wrong then I'm sure Tim or a member of his crew will correct me).
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I thought that RSB was only installed on the -500's, if the aircraft was in cruise and the speed picked up, at a predetermined mach figure the speed brakes deployed to slow the aircraft down before it pitched up. It was a while ago.
Remember, but not to well, doing some checks on the Yaw Sas system as the aircraft was reported it felt like it was jumping around either left or right turns, and found that the rudder in 1 direction only was moving the opposite way to that required.
I have many hours on them, trying to keep them flying, but not since 1994.
Remember, but not to well, doing some checks on the Yaw Sas system as the aircraft was reported it felt like it was jumping around either left or right turns, and found that the rudder in 1 direction only was moving the opposite way to that required.
I have many hours on them, trying to keep them flying, but not since 1994.
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Quite correct allthatglitters, the RSB was only on the -500.
And, as far as pax flying goes, yes still used, and more on the way, but not that many currect crews available, especially Captains...and they are not inexpensive.
And, as far as pax flying goes, yes still used, and more on the way, but not that many currect crews available, especially Captains...and they are not inexpensive.
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Got a chance of buying one, do you know on the internet were I can get a full spec on this beauty.
Do you reckon a retired captain would come out of retirement to fly??
Do you think a runway of 2500ft is long enough??
Do you reckon a retired captain would come out of retirement to fly??
Do you think a runway of 2500ft is long enough??
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Payload or range limited on that runway, TANGO100, regardless of specific model, but if no obstacles are present, 22 (or even 27) flaps can be used for takeoff with the standard body aeroplane.
Send a PM is you desire more info.
Send a PM is you desire more info.
I was told by a friend who was involved very early on with the DC10 that Douglas had designed a DLC system for it but found it was not required during flight testing so deleted it before the aircraft went into service. He claimed there were diagrams of it in his training notes which the course was told to discard (thankfully according to him as it looked a hideous mechnical arrangement).
I have to agree with cirrus01 earlier about the L1011's maintenance and reliability. The following is something I wrote for a Tristar thread over a year ago but never posted it.
Unfortunately many of the features that delighted flight crews were the very things that plagued the maintenance people especially in the flight controls/autoflight area. The L1011 was an overly complex aircraft for the job it was meant to do. The complex electronics used analogue computer technology except for a few late model aircraft with digital autopilot boxes. The L1011 never achieved the level of maturity that most aircraft arrive at after a few years in service and many systems required too much tender loving care throughout its life whereas other systems started well and got worse with age! Performance of the autoland system easily beat all its contemporaries but was difficult and time consuming to maintain and troubleshoot especially if operating to Cat 2 or 3. The flight controls were a maintenance nightmare as the aircraft aged with numerous wear, friction & bearing failure issues. I have never known an aircraft that experienced as many partial flap/partial slat landings as the L1011. The TE flap system was mechanically complex, lacked robustness, was a lubrication nightmare (try counting the number of grease nipples; about 900 to 1,000 with many hidden) and was prone to jams. The LE Slats suffered control problems as well as some mechanical issues. The flap load relief system never worked reliably and eventually operators were given the option of deactivating it and limiting landing flap to 33 degrees (approach flap) which most gladly did. The numerous rudder control and limiter pressure switches and solenoid valves installed above No. 2 engine were an access problem for line stations. The air-conditioning was woeful in the hot and humid climate in which we operated. The instrument cooling system was inadequate - with round dial engine instruments the centre panel got red-hot affecting instrument reliability. ?Rain in the plane? in the tropics was another never-ending problem with older aircraft. The pressure hull leaked like a sieve and cargo door seals were a notorious problem being easily damaged or pulled out of their retainers by container impact. The APU was hopeless in hot conditions with insufficient output for proper ground cooling or engine starting (at least it was quick and easy to replace). Pneumatic system valves exhibited poor reliability throughout much of the L1011?s life. The fuselage bilge area corroded too easily in a humid environment and there were numerous structural issues, rear spar fatigue at several locations being one of the big ones. The main landing gear experienced a number of major component failures. The toilet system was a headache especially as it aged. Who in his right mind would put a toilet tank, flush pumps and associated plumbing and waste lines in an avionics compartment and then mount the Indicator Light Control Box that controlled every cockpit annunciator light including switchlight flowbars right under the fwd lavs where it could get wet? The Dynatube hydraulic fittings, which were reputedly designed for rockets/missiles, would have best been left on these single use vehicles and not installed on an aircraft where component replacements often resulted in sealing face damage and subsequent difficult-to-fix leaks.
I could go on but the above list is enough to indicate the maintenance guys? frustrations with the Tristar. Our L1011 fleet required 3 times the man-hours to maintain compared to our 747 classics.
It was certainly an interesting aircraft and it definitely provided job security for the engineering and maintenance people but always needed far too much TLC and manhours.
With regard to its limited success (only 250 built) Lockheed originally intended to produce two completely different models; the L1011-1 for domestic use and a similar sized ?2 with 6 wheel MLG bogies like a 777 for long range use, and publicly disparaged the Douglas approach of designing the DC10-30 as a derivative of the ?10 from the very start claiming a dedicated long range model was more efficient. Perhaps so, but in the end Lockheed could not afford to build the ?2 and the shortened ?500 was a shabby compromise with limited sales.
I have to agree with cirrus01 earlier about the L1011's maintenance and reliability. The following is something I wrote for a Tristar thread over a year ago but never posted it.
Unfortunately many of the features that delighted flight crews were the very things that plagued the maintenance people especially in the flight controls/autoflight area. The L1011 was an overly complex aircraft for the job it was meant to do. The complex electronics used analogue computer technology except for a few late model aircraft with digital autopilot boxes. The L1011 never achieved the level of maturity that most aircraft arrive at after a few years in service and many systems required too much tender loving care throughout its life whereas other systems started well and got worse with age! Performance of the autoland system easily beat all its contemporaries but was difficult and time consuming to maintain and troubleshoot especially if operating to Cat 2 or 3. The flight controls were a maintenance nightmare as the aircraft aged with numerous wear, friction & bearing failure issues. I have never known an aircraft that experienced as many partial flap/partial slat landings as the L1011. The TE flap system was mechanically complex, lacked robustness, was a lubrication nightmare (try counting the number of grease nipples; about 900 to 1,000 with many hidden) and was prone to jams. The LE Slats suffered control problems as well as some mechanical issues. The flap load relief system never worked reliably and eventually operators were given the option of deactivating it and limiting landing flap to 33 degrees (approach flap) which most gladly did. The numerous rudder control and limiter pressure switches and solenoid valves installed above No. 2 engine were an access problem for line stations. The air-conditioning was woeful in the hot and humid climate in which we operated. The instrument cooling system was inadequate - with round dial engine instruments the centre panel got red-hot affecting instrument reliability. ?Rain in the plane? in the tropics was another never-ending problem with older aircraft. The pressure hull leaked like a sieve and cargo door seals were a notorious problem being easily damaged or pulled out of their retainers by container impact. The APU was hopeless in hot conditions with insufficient output for proper ground cooling or engine starting (at least it was quick and easy to replace). Pneumatic system valves exhibited poor reliability throughout much of the L1011?s life. The fuselage bilge area corroded too easily in a humid environment and there were numerous structural issues, rear spar fatigue at several locations being one of the big ones. The main landing gear experienced a number of major component failures. The toilet system was a headache especially as it aged. Who in his right mind would put a toilet tank, flush pumps and associated plumbing and waste lines in an avionics compartment and then mount the Indicator Light Control Box that controlled every cockpit annunciator light including switchlight flowbars right under the fwd lavs where it could get wet? The Dynatube hydraulic fittings, which were reputedly designed for rockets/missiles, would have best been left on these single use vehicles and not installed on an aircraft where component replacements often resulted in sealing face damage and subsequent difficult-to-fix leaks.
I could go on but the above list is enough to indicate the maintenance guys? frustrations with the Tristar. Our L1011 fleet required 3 times the man-hours to maintain compared to our 747 classics.
It was certainly an interesting aircraft and it definitely provided job security for the engineering and maintenance people but always needed far too much TLC and manhours.
With regard to its limited success (only 250 built) Lockheed originally intended to produce two completely different models; the L1011-1 for domestic use and a similar sized ?2 with 6 wheel MLG bogies like a 777 for long range use, and publicly disparaged the Douglas approach of designing the DC10-30 as a derivative of the ?10 from the very start claiming a dedicated long range model was more efficient. Perhaps so, but in the end Lockheed could not afford to build the ?2 and the shortened ?500 was a shabby compromise with limited sales.
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So far as I know, direct lift control is not used on any other civil aircraft type. Also used on the space shuttle, for pinpoint accurate landings.
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>>I have never known an aircraft that experienced as many partial flap/partial slat landings as the L1011. The TE flap system was mechanically complex, lacked robustness, was a lubrication nightmare (try counting the number of grease nipples; about 900 to 1,000 with many hidden) and was prone to jams. The LE Slats suffered control problems as well as some mechanical issues.<<
Strange you should say this, CV880, as in 25 years operating the aeroplane, never had a slat or flap problem, except once, where the slats failed to retract on departure, which required a return.
Now, lets look at the slat system.
If you had a hydraulic failure, the slats would absolutely not retract, but would firmly lock in place, thus avoiding ANY of the DC10 slat difficulties, ala the AA DC10 at ORD.
Further, hydraulic fusing kept the fluid in, should a leak develop, something the 747's and DC10's could not , except after modifications following fatal accidents.
Reputable airlines sent their maintenance techs direct to Lockheed Palmdale to LEARN how to maintain the aeroplane correctly.
With Lockheed, the quality went in, before the name went on.
Both Boeing and Douglas were second rate with design redundancy.
Small edit.
Do a search, ferrydude, you will find the answer.
In fact, due mainly to DLC, the early space shuttle crews trained initially on, would you believe, Delta Airlines L10 sims in Atlanta.
A fact, if you are old enough to remember.
Strange you should say this, CV880, as in 25 years operating the aeroplane, never had a slat or flap problem, except once, where the slats failed to retract on departure, which required a return.
Now, lets look at the slat system.
If you had a hydraulic failure, the slats would absolutely not retract, but would firmly lock in place, thus avoiding ANY of the DC10 slat difficulties, ala the AA DC10 at ORD.
Further, hydraulic fusing kept the fluid in, should a leak develop, something the 747's and DC10's could not , except after modifications following fatal accidents.
Reputable airlines sent their maintenance techs direct to Lockheed Palmdale to LEARN how to maintain the aeroplane correctly.
With Lockheed, the quality went in, before the name went on.
Both Boeing and Douglas were second rate with design redundancy.
Small edit.
Do a search, ferrydude, you will find the answer.
In fact, due mainly to DLC, the early space shuttle crews trained initially on, would you believe, Delta Airlines L10 sims in Atlanta.
A fact, if you are old enough to remember.
Last edited by 411A; 5th Mar 2006 at 21:50.