Tristar's Direct Lift Control

[LEM]

Any (ex) Tristar pilot would enlighten us on Direct Lift Control (spoilers deploying and retracting to maintain the glide path, rather than changing pitch)?
Is it easier-nicer-more accurate or what?

That would be nice! Thanks

LEM

[HotDog]

I had 5000 hrs plus on the Tristar, albeit as a flight engineer. DLC was akin to speedbrakes on a glider, if you are familiar with that, except it was automatic. Supposed to have been the ants pants of approach and landing design but still experienced the hardest landings at times, of my entire flying career.

[411A]

Some of the spoiler panels moved to a null position (7 degrees) when the flaphandle was moved past the 30 degree position.

Forward pressure on the pole resulted in spoiler extension (to a max of 14 degrees), whereas aft pressure on said pole resulted in spoilers retracting.

Worked OK, for the very finest in automatic approach/landings.

Required a definate technique for manual flying.
As some found out, the Boeing 'push' did not work.

[VR-HFX]

LEM

HD and 411A have answered your query but whilst cleaning out my old computer the other day I found an old file which may be of use if you have a broader interest in the Tristar....

All of the flight controls on the Tristar are hydraulically actuated and none has any form of manual reversion. This simply means that, in the event of the failure of all hydraulic systems, the aeroplane would be completely uncontrollable. Before you blacklist all airlines flying Tristars, remember that the flight crews are all made well aware of this fact during their conversion and that they are all only too happy to operate the aeroplane. Prior to going on to the hydraulic actuation of these controls, and all of the rest of the hydraulic services, I will briefly run through these flight controls with particular reference to those that may not be quite so familiar to all of us.
Pitch control is maintained by the use of an all flying tailplane to which is attached a relatively normal elevator. They move in conjunction, and the elevator is mechanically linked to the tailplane. Control is by two servos and if either jams it can be disconnected. Trim is automatic and is achieved by the positioning of both surfaces Each time trim is used the control column takes up a new neutral position. The rate of movement of the trim is automatically varied for different speeds.
The rudder is reasonably conventional and incorporates a yaw damper whose purpose is to help eliminate "Dutch Roll". A series of "stops", which are actuated by speed sensitive switches, automatically limits arc of travel of the rudder in various conditions of flight.
Most jet airliners are equipped with two ailerons on each wing and the norm has been for the outboard aileron to be automatically locked central at high speed. The Tri Star differs in that all ailerons are operating at all stages of the flight. Extra control in the rolling plane at slow speed is needed and is provided by differential operation of the spoilers.
Six spoilers are fitted to each wing and their functions are many and wonderous to behold. They operate in a multitude of combinations to achieve these functions which are as follows:-Speed Brakes (at any time in the flight), Roll control assistance (when flap is extended), Lift control (on approach), and automatic extension after landing. When spoiler extension is demanded the aircraft decides which ones will extend and which ones will not. To make these decisions it gathers information from a series of speed sensitive switches, flap position indicating switches, Throttle position switches, and "squat" switches on each of the three U/C. legs.
Four double-slotted Fowler flaps are fitted to the trailing edges of the wings and alternate between the spoilers, while there are seven slats, or leading edge flaps, fitted to each wing. The slats go out with the first extension of the flaps (3 degrees), and are responsible for the very marked difference in the stall, and approach, speeds when either flapped or clean.

Hydraulic Systems.

There are four hydraulic systems in the Tristar. They are completely independent of each other. Each has is own reservoir and pressure source, and a loss of fluid in one will not affect any other. Pressure is provided by E.D.P.'s, P.T.U.'s, A.T.M.'s , electrically powered pumps and a R.A.T.
"A" System is powered by an E.D.P. on No. 1 engine and has, as an alternate power source, a PTU from System "B".
"B" System is powered by an E.D.P. on No. 2 engine and, as alternate power source, has an A.T.M. and an electric pump,
"C" System is exactly similar to "B" System but in addition may be powere by the R.A.T.
"D" System is exactly similar to "A" System.
The RAT is extended automatically when needed, and can be manually extended on the ground. It is normally "pinned", for safety reasons, when the aircraft is on the ground.
The most important hydraulically operated services are the flight controls and each of them is supplied with a multitude of alternate pressure sources, either by extra jacks to the same control surface or to mated surfaces (ie spoilers). There are two independent sets of wheel brakes. U/C. can be free falled, and flaps can be done without .

Flight Director/Auto Pilot, Area Navigation, & Auto Land.

Equipment includes, two Auto Pilots. two Flight Directors. three computors, two Inertial Nav. Systems and two VORTAC's.

The information used by the autopilot is the same as used by the corresponding flight director. Only one autopilot may be operated at a time, except in "Autoland" mode, but the flight directors may be operated in conjunction or independently and either automatically or by manual input. The third nav. computor monitors the other two at all times and any one of the three that is "odd man out" is automatically discarded. VORTAC stations are automatically tuned as the a/c. moves along track. As an alternate to automatic navigation the autopilot in use may be manually controlled
Movement along track may be monitored on a C.R.T. type display, a complete sector flight plan may be fed into the computer, automatic interceptions of VOR radials and ILS's can be made, an auto throttle is fitted, and either height or speed may be maintained.
Auto landings are available wherever there is a suitable ILS. Interception of both the ILS and the G/S. are automatic. A "Go Around" facility is incorporated, it is armed when flap in excess of 33 degrees is selected and it is activated when a button is pressed.

[411A]

VR-HFX has covered the TriStar systems rather well...while there are very slight differences between models...all generally correct.

As to flight control redundancy...the TriStar has no equal in this regard, designed right in from the begining.

As an example, a TriStar was landed in the middle east with only one half of one hydraulic system quantity remaining..and done by a brand new First Officer, who had very good training.

The dual channel dual autopilots fitted provided superb automatic approach/langings. CAT IIIC capability built in, from the start...by the folks who migrated to Lockheed from the HS Trident team, so I was told. The only thing missing was Smiths stamped on the autopilot control panel.

The Lockheed TriStar was the cream d'la cream of early design wide-body aircraft, IMHO.

Just like the Lockheed 1649A was the epitomy of piston-engine airliner designs. Douglas made more...Boeing made a lot more, Lockheed provided the most technically advanced designs.

[LEM]

Thanks a lot, gentlemen, for your descriptions!
I had already heard, in fact, that technologically the Tristar was better than the DC10.
For example on the DC10 you have to keep an eye on which tank the n°2 eng is feeding from, for a possible imbalance. Not so on the Tristar, where that is equally shared between tanks 2L and 2R by a flow equalizer.

It seems Direct Lift Control is unique in commercial airliners.
Did it require a different mental approach on maintaining the glide?
Did you like it?

ps: one silly question: I have seen various Tristar takeoffs: everytime it seemed to be underpowered (quite flat climb gradient, at least initially). Was that a false impression?

Again, thank you for your time!
LEM :8 :8

[VR-HFX]

I forgot to add...the nicest a/c I have ever flown...by far...and the list includes:
C-130, PC-3 B-707/747/777.The L-1011 was light years ahead of it's time and apart from being a bit under-powered at MTOW and short on range (cf: DC10-30) it was the best a/c per dollar that CX ever owned...a license to print money.

[HotDog]

Right on HFX and what great night stops we had together! Cheers, HD.

[411A]

LEM,

Some of the early TriStar models powered by the RB.211-22B engine were a bit underpowered.

Later on, the RB.211-524B4 engine was fitted to the standard body aircraft, with excellent results...lots of power.

The last model produced, the -500 series had a slightly shorter fuselage, longer wing, and much more fuel...12 hours range. In addition, had active ailerons, for a smoother ride in turbulence, amoung other things. 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.

Personally flew the Lockheed TriStar for over twenty years with four different carriers...and she never let me down.

[VR-HFX]

Ah yes HD...the good ol'days..with PJ the Greek in white shoes at JJ's and a million other fun evenings...alas all gone now....except for the black coffee which is the only thing that is better than it used to be.

Keep well.

[GlueBall]

The -22 was rated at 42,000 Lbs thrust, and the latest -524B4 version was rated at 50,000 Lbs thrust. Big difference in power.

What killed the TriStar program was the failure of Lockheed to offer customers alternate engine manufacturers. It's what Douglas and Boeing had learned early on when building their 4 engined DC8s and 707s. Either was available with RR or P&W powerplants.

[cirrus01]

Might have been a nice aeroplane to fly........but it was an absolute pile of C##P to work on !.........One of the best moments of my career was when my employers stopped flying the "Hangar Queens"

[411A]

Sad to hear that, cirrus01.
Oddly enough, UL had (at one time) the highest daily utilization of any TriStar operator...16.6 hours, as I recall.
All this, and maintaining out of an old blister hangar in CMB.
Well trained ground guys....who later migrated to GAMCO in AUH.

[ReginaldSpotter]

Glue Ball,
the Tristar failure was entirely due to the RR collapse.
They tried desparately to use alternative engines but there were two major problems.
The only suitable engines at that time were the other 2 big fan engines.
The GE CF-6 and the PW JT9.

First problem was the fact that the RR was a 3 spool engine and the other two were 2 spool engines. different trust line, diamter and CofG, hence major re-design

Second problem was there were NO engines available.
If you remember there were pictures at the time of lines of B747 sitting in Seattle with concrete blocks in place of engines. This was because PW had their share of problems with ovalation ( Not ovulation:D ) so none of those available.
GE were flat out producing for DC10 ( and I suspect Douglas would have put their oar in at GE supplying for the opposition ;) ;) )
So Lockheed, being the new boys on the block had to wait it out.
There was always promises that RR would be bailed out but it was too long in coming.
:{ :{

[LEM]

What is ovalation? :confused:

[VR-HFX]

LEM

Now that is a very good question.

I suspect it is what I used to do when Ms HFX was ovulating...run around an oval until I was too tired to do something that would take another million out of my bank account over the ensuing 20+ years.

In this context it is probably what P&W did when Lockheed expressed amorous intent.

But I could well be wrong.

[ReginaldSpotter]

LEM,
These were the first of the "big" fan engines so bound to be a bit of a learning curve:D :*
The engine started off round when cold but went oval during running with temperature increase. Not a good thing where rotating machinery is concerned

This problem did not occur with the concrete blocks in the place of engines :O :O
There were lots of pics of the Boeing Flight line at that time.

[411A]

The early RB.211's were certainly not without their problems as well.
Recall Eastern Air Lines had to do an 'engine run-up' before brakes release, and takeoff commenced.

Then, noticed three RB.211's on the ramp in San Juan (1974) with all the last stage turbine blades gone...gone as in melted away .
Must have been rather expensive.

[GotTheTshirt]

411,

Wasnt the reason that Esatern did that run up to make sure that all the MCD's had seals installed in them ? :cool:
Didnt all three engine keep running with no oil ??

Re the San Juan 1974 - yes there were a few pilots around that operated like that in thise days. I guess operating a those new fangled engines took a bit of getting used to

[D-Aviator]

You omitted the best thing about DLC.
If on approach with DLC and you need to initiate a Go Around, by advancing the throttles, the spoilers are sent back to zero from the 7 degree DLC nul position and you have an instant 1000 feet per minute rate of climb.
So while the engines are still winding up you are now over flying the runway obstruction in a calm cool collected manner, and not praying that the donks will wind up in time as on todays modern Busses and Boeings.
Clever chaps the guys at NASA-Ames who came up with the idea that Lockheed adopted so very well.
Could be done easily with the flying software of todays aircraft. Maybe on the B787????

[allthatglitters]

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.

[ZQA297/30]

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!)

[gas path]

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???

[ZQA297/30]

Gas path, you're right about MDLC, but I believe roll /speed brake is correct, the QRH had a section on "roll/speed brake light".

[TURIN]

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.:{

[411A]

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...:E
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.

[TANGO100]

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

[ZQA297/30]

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?

[Basil]

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).

[TANGO100]

How would a tristar fair on a runway of 2500meters ils on both ends??

[allthatglitters]

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.

[TANGO100]

Are tristars still flying passengers about nowadays, i might buy one and put one in service, any pilots wanting a part time job

[411A]

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.:E

[TANGO100]

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??

[TANGO100]

Dimensions
(m)
2250x46 sorry this is the dimensions of the runway

[411A]

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.

[TANGO100]

411A pm sent to you
Thanks

[CV880]

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.

[ferrydude]

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.

I'm gonna have to call BS on the Space Shuttle using DLC. I'll retract it if Capt. 411A can provide an appropriate reference to such.

[411A]

>>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.

[galaxy flyer]

411A, you might chime in being the L1011 expert.

I believe hydraulic fusing came in as a result of the Saigon C-5 crash where an aft cargo door failed and took out all four systems. The Galaxy had fuses everywhere and never lost more than two systems in my knowledge. The 1011 pilots, in my experience, said the L1011 was like the C-5, but perfected. At Eastern, the L1011 was U/S so often our cleaners wouldn't hustle a job on it because it wasn't anywhere in a hurry, but the -9 or 727 at the next gate was leaving.

I would agree on the lav system problems. The C-5 lavs were right over the landing gear logic panels, the inevitable leaks cause all kinds of unpredictable gear problems. Also, I don't know if it was Dynatube, but the swedged hydraulic fittings were a nightmare. Not always capable of being repaired except at C-5 bases and not always then. I blew a #1 system pressure line just inside the fuselage over France. Filled the cargo area with hydraulic mist and fluid, landed back in Germany. Before undoing my seatbelt, the hydraulic folks were talking about a 72-hour repair. They were right, too.

Dreary stories, but the 1011 and it predessor were magnificant techological marvels...........WHEN THEY WORKED.

GF

[ferrydude]

Sorry, I'm calling BS on the Delta sim story also. I can't remember what didn't happen no matter what my age. Relevant links to references please.

[411A]

Ferrydude,

Give a call to Lockeed Greenville, and ask for Robert Taylor, the TriStar support manager.
He will have the information you require.
Or, call a few old ex-DAL guys, who were in L10 fleet management.
They will set you straight.
Hey, spend a quarter for the telephone.:rolleyes:

[ferrydude]

Why not share your "facts" with the rest of PPRUNE and post your references here.

[rhovsquared]

We still have amazing advances from Lockheed (very proud company indeed) F-22 Raptor.... that also has DLC.... it lifts directly outta the field with no runway:D although I can honesty say would not want a Boeing ICBM chasing me either...

[ferrydude]

Hmm, the Boeing partners in the F-22 Raptor might take issue with your assessment of where the "amazing advances" came from. In any event, it is now Lockheed/Martin, a very different company than the Lockheed that existed at the time of L-1011 development.
http://www.boeing.com/defense-space/military/f22/

[rhovsquared]

anyway we still have amazing advances from Boeing :ok: -my favorite company anyway

[777fly]

The Tristar DLC system certainly allowed a very stable approach attitude, but having flown a few wide body a/c since the Tristar, I could not say that the difference is detectable in the cabin. From the pilot's point of view, it did allow a more rapid change of vertical speed during the approach, since lift was directly affected by spoiler deflection via a simple stick pitch input, rather than having to change wing angle of attack through a change in aircraft attitude.The system gave a rapid response in the go-round, with virtually no sink after the TOGA button was pressed.The secret of a smooth landing in the L1011 was to always keep some positive back-pressure on the control column, after the flare was initiated, until touchdown.This stowed the spoiler panels from the 7 degree null position to 0 and helped to cushion the touchdown, which could be really smooth. Any relaxation of the back-pressure, or forward pressure ( you don't really do that in the flare, do you?) redeployed the spoilers to ( or beyond ) the 7 degree position and could dump the aircraft on the runway.
To answer a previous question: yes, the Tristar could land on a 2500m runway and we often did that. As I remember, things became challenging around 2200m, depending upon weight. Landing on full length 09R at LHR after an air-test, admittedly a minimum weight, we used max autobrake to stop. There was no time to pull reverse above idle before we reached taxy speed and we had to apply power to taxy forward to clear at the old runway threshold (block 79). The ground roll was around 800m or less, you can check it for yourself. That said, most modern jets can pull up extremely quickly. Its a shame that the only thing that simulators cannot simulate is max braking, it is literally a breathtaking experience. The Tristar was a good 'stopper' and much better than the DC10, which was very weak in that respect. (Yes, I flew both)

[Swedish Steve]

When I was involved (as an engineer) with Nordic East, we ran regular trips ARN-CFU which has a 2375m runway and no taxiways. The crews seemed to handle it with no problems and we were in full charter config with 350pax(only small L4 R4 doors).

I was an engineer on the Tristar for 7 years with GF and then Line maint for TWA at ARN then the Nordic operation based at ARN. Loved the aircraft. It went wrong a lot but didn't let us down much. So much was allowable in the MEL. In our days with the two Nordic Tristars we changed one engine time expired in three years. In the same hangar Premiar changed 22 CF6s on their ex DL DC10s!

[loofah]

Ask the crew who ran off the end at Leeds Bradford about stopping, and the subsequent enquiry. if I recall they were tankering from Mahon.