TriStar active ailerons: gimmick or..?

[skippiebg]

30 years ago the TriStar's active ailerons were touted as a huge advance but...

- Lockheeds never adopted them on the long bodied TriStar where they surely would have been just as useful (late 200s had as long a range as the 500 and then some, judging by reference literature)

- nobody else was in a hurry to adopt them on their hardware, either (may have been a patent issue?)

- today (well, mid-80s onwards) we have winglets/raked tips instead to cut induced drag and nobody seems troubled by load alleviation and hence active ailerons (to the best of my knowledge which admittedly trails off late 1980s).

So was it all a typically Lockheed high-tech gimmick - just like Direct Lift Control which caused as much trouble as it was supposed to solve and has been (I understand) switched off wholesale on surviving L-1011s?

I couldn't help noticing at the time that in the run up to privatisation BA got rid of its 1011-500s pretty sharpish, though they did admittedly lease a couple later on in the decade.

Just venting my suspicions that the TriStar was a bit of a job creation scheme with lots of hot air driving it. Lovely to look at, I'll grant you...

Sorry if the topic has been raised elsewhere. Looked, couldn't find it.

[TopBunk]

You should know better than to start such a topic. Wait .... here it comes .... the rumble of a distant 411A to support his beloved Tristar:\:rolleyes:

[skippiebg]

Aah, never one to shrink from putting cats among pigeons! Bit of a fan of La Tristar myself, looks wise...

[allthatglitters]

The -500 where touted for a range which it initially didn't make, the early aircraft went back to Lockheeds and 4.5 feet where added to each wing along with longer, active ailerons and uprated engines (524B4 as an option), which was what the 6 BA aircraft got, they also came back with other modifications such as RSB.
The -100/-200 had a single cell in the centre wing box for fuel, and the -500 had 3 cells for fuel, so your statement about them having the same range is incorrrect.
As to the -250, not having worked on them I do not know there cell set up or range.:{

[411A]

Hardly.
Now, lets have a look at the various models of the 'ole tri-motor.
The standard body aeroplane came with several fuel arrangements, two different models of engines, and had a MTOW of 215 tons, on later varients.
Enter the -500.
More fuel (95 tons vs 80...or less), an extended wing, shorter body etc, and the whole idea was for a very long range jet transport.
I personally have done 12 hours non-stop with the machine.
Many times.
The active ailerons were designed to eliminate extensive wing mods, IIRC.
Looking further, I have had, in 27 years of flying the L1011, absolutely no problems whatsoever with the DLC system, nor with the active ailerons (or MDLC) on the -500 model.
None.
Zip.
There were only six examples of the -250 modified, all by Delta Airlines.
These had the weight increased to that of the -500 model (with limitations), the same fuel capacity, bigger engines but of course were not equipped with active ailerons nor MDLC, and were not capable of the longer range that the -500 offered.
Some folks apparently like to throw stones at the TriStar, simply because they don't understand the inner workings of the beast.
One must remember, the L1011 is the only first generation wide-body civil jet transport that has never crashed due to an aircraft system malfunction, the pilots flew it into the ground for a variety of reasons or failed to use the proper checklist.
As for reliability today, I just completed an extensive schedule of Hajj flying, and the specific L10 airplane that I operated had no delays nor cancellations whatsoever.
None.
Zip.
The automatic approach/land also worked as advertised...it must be experienced to be believed, it is that good, even by todays standards.
Not bad for a thirty seven year old design.

Another thought.
Two years ago I has having a conversation with a recently retired DAL senior vice-president.
He mentioned...."our TriStars made the most money for Delta of any airplane in the fleet, bar none."
Delta should know, they had sixty nine of 'em, and were the largest fleet operator.

Seems entirely reasonable to me.:D

[millerscourt]

I will give 411A his due. He has a very good memory for one so old:{

[skippiebg]

Well, on range I've got some potted refs that state the 200 had 4850 miles and the 500 had 4580. Looks like a typo, but I recall Flight quoting similar figures (about 300 miles extra for the 200) in its proper old commercial aircraft surveys before it became an accountant's mag. All very odd if true since the 500 was supposed to be the long-ranger. Yes, the 250 was an aftrmarket mod by Delta.

Interesting to hear DLC is still operational. Had heard it had been stripped off years ago by some ops and had been disabled by others, leaving precious few if any operational by now. Must cause extra drag and noise on approach, surely..?

And yes, the active ailerons were put in so the wing could be stretched by 9ft without any structural beef up. Which still leaves me wondering why no active ailerons on other types. (I may be wrong here, since 320s, 330s, 340s, 777s and all that leave me pretty cold.) If the reason was a patent issue, Lockheeds surely could have sold their rights as they were desperate for TriStar funding. So the insiduous thought inside me mind is - they were not as good as winglets, etc.

On reliability, I'm sure it's improved, but can't help recalling what I heard from Court Line people donkeys years ago. Suffice it to say, thank Goodness for the Laker Tens that regularly had to come along and lend a hand...

[TopBunk]

I said he wouldn't be long .......;)

[Clandestino]

Some 320s (seemingly the older ones) do have load aleviation function (LAF) which works through ailerons and some outboard spoilers. I´ll be back with more info when I dig out my FCOM.

EDIT: LAF on A320 uses ailerons and two outboard spoilers and deflects them simmetrically upwards when there´s more than 0.3G difference between commanded and actual load factor. If it gets degraded or inop, there are no speed or weight penalties and no flightcrew procedures dealing with it.

In my employer´s fleet, only one older & dry-leased A320 has LAF. The ones we bought new don´t have it.

[galaxy flyer]

411A:

Since your memory is SOOOOOOOOOO good-how many hull losses did the Tri-Star suffer? As an EAL grad, we lost the one in the Everglades. Several near-misses, esp. the one with the three-engine oil leak. Saudia lost one on the ground (cabin fire), DL lost the one in a TRW at DFW, but are they any others??

GF

Lockheed builds excellent, lucky planes! :ok: Compare to the MD-11! Mega-insurance headache:ugh:

[fergineer]

Galaxy,

7 hull losses 1011 Everglades, 1014 Fire after an aborted TO, 1026 Ground fire, 1061 Sabotage, 1114 Ground fire, 1163 Crashed on approach, 1169 destroyed by fire.

Thats all I think but I agree with 411A they were a fine jet and in all the time I flew them no problems with the DLC. Agree with the auto land as well untill I had the tail strike with the Auto pilot runaway!!!!!!

Thats all

[411A]

http://aviation-safety.net/database/dblist.php?field=typecode&var=336%&cat=%1&sorteer=datekey&page=1

[galaxy flyer]

Pretty good record overall-especially when take out the ground events, not on operational flights.

GF

[skippiebg]

The TriStar has long been known for safety, so we're in danger of rediscovering the wheel here. It's not its safety record but its tech whizzery that I am probing into by suggestring some of it wasn't all that. Or rather, wondering aloud whether it was a cul-de-sac, or genuinely useful.

Put simply, it seems the structurally heavier long bodied version achieved much the same range as the active aileron/extended tip short body, which makes sense not, unless we assume the active ailerons/wingtip mods were a gimmick.

Additionally, I still can't work out the status of DLC. Can't remember my source, but its gist was that DLC was removed by operators as a drag, noise and tech generator.

[Litebulbs]

What I have read shows the 500 having a range of 6300 miles which is alot further than the 200.

[skippiebg]

Are we talking nautical or statute? I've got 3 potted books all showing 4580nm for the 500 and 4850 for the 200, or 5100 st. m. versus 5400 st. m. at 225 t v. 230 t. Max AUW was 250 tons if I recall (for both the 500 and 200). At 250t AUW, 6300 st. m. should be about right. My potted books are admittedly very highly "iffy", but I do recall Flight citing much the same data. Must call on Westminster Reference Library one of these days...

[idg]

Was told by Lockheed in the early days that the fundamental reason for DLC was to reduce touchdown 'spread' during autolands. This enabled the ole girl to be certified to CAT 111c in the UK (a BEA requirement). I believe that she was the first widebody so certified. Indeed perhaps someone could enlighten us as to whether the other two (Jumbo, DC-10) got such certification early on?

ACS was indeed fitted to limit wing loads with stretched wing tips but note that later a/c (ie not the early BA -500s) had a stronger wing (with stretch incorporated already)and the ACS (as I recall) had a smaller travel.

[411A]

All quite true, idg, the DLC was there for a reason.
The TriStar was the first wide-body to achieve CATIIIC and be stage three noise compliant at all weights, right out of the hangar, not added on later.
Having flown both the -500 model and the earlier -200's and 250's, the -500 will sail right on past a -200/-250, when the latter types have dry tanks.:ugh:
No operator that I'm aware of has disconnected DLC as a normal mode of operation, nor should they as it is very reliable.
The only downside is for the pilot who tries the 'Boeing push'...they learn straight away that it ain't a good idea.:E

[Graybeard]

"Was told by Lockheed in the early days that the fundamental reason for DLC was to reduce touchdown 'spread' during autolands. This enabled the ole girl to be certified to CAT 111c in the UK (a BEA requirement). I believe that she was the first widebody so certified. Indeed perhaps someone could enlighten us as to whether the other two (Jumbo, DC-10) got such certification early on?"
--------

I heard from more than one source that the touchdown spread was so tight it spurred BA to inquire of LHR whether there would be a downside to the plane hitting the exact same spot nearly every time. LHR was horrified, and asked them to put some dither into the touchdown aim point.

Lockheed has always built a stiff wing, which is great for aerodynamics, at the expense of gust loading. The DC-10 has a moderately stiff wing, and you wonder how they can ever calculate angle of attack on the outboard engines and wing sections of a 747, even in mild turbulence.

Lockheed stiff wings have suffered fractures, including the loss of a few C-130s, and major re-works of their wings and wings of the C-5A.

Problems with Bendix's supposed CAT III autoland in the DC-10 was blamed for the bankruptcy of Douglas Aircraft, and its takeover by McDonnell. I don't believe any airline made it operational, although I've ridden through several autolands in production testing, as they were required to demonstate it before delivery to some customers.

I never heard that the dual-dual Sperry autoland was particularly successful in the 747, but don't know for sure it wasn't.

The Collins dual-dual autoland L-1011 was the first commercially successful CAT IIIc, I believe, and the Collins in the L-1011 was the first digital autoland system, preceding the triplex Collins system in the 767 by a couple of years.

GB

[skippiebg]

Thanks, 411 - at last now I know that 200s have less range than 500s! Phew! And that DLC was hot. I admit to having been misinformed.

Greybeard, I thought McDonnells took over Douglas in the mid-60s (1967?) because old Donald D was selling Nines at sweetheart rates and his son was undercutting even the sticker price... Didn't the Ten's AFCS problems come way later, in the 70s..?

[FE Hoppy]

As a matter of note.

steep approach mode on the latest all singing ERJ uses..............
Spoiler panels deloyed to a 10 degree position and then modulated with column input.......


sound familiar??

[411A]

Uh oh...DLC.
Imagine that....:}

[glhcarl]

When the L-1011 spoilers are used in the DLC mode there nul position varies by model:

-1, -100, -200 and -250 the nul position is 7 degrees.

-500 the nul position is 9 degrees.

The DLC can not be disconnected, the only way to disable it would be to shutoff the all four inboard spoilers.

The DLC system uses both pilot inputs (stick inputs) and automatic inputs from the Flight Controls Electronic System (FCES) to control the sink rate. If the aircraft is above the glide slope and the pilot pushes the stick forward the spoilers will extend to assist in reducing the altitude. However, if the pilot does nothing, the FCES extends the spoilers to regain the proper altitude. If the aircraft is below the glide slope the same scenario applies except the spoilers retract allowing more lift and the aircraft again regains the proper altitude.

[Graybeard]

"Greybeard, I thought McDonnells took over Douglas in the mid-60s (1967?) because old Donald D was selling Nines at sweetheart rates and his son was undercutting even the sticker price... Didn't the Ten's AFCS problems come way later, in the 70s..?"
-----
I'm only reporting what I was told by Douglas reps in the late 1970s. I believe the DC-10 development was well under way in 1967, and certified in 1970. I'm sure there was more than one cause of the bankruptcy.

Speaking of price cutting, Pacific Southwest Airlines and other early buyers of the MD-80 at $24-26 Million each were mighty angry when AA came in and bought them for $18 Million per. AA had the advantage of a big order at a time when sales were lagging.

When there is a surplus of product, the price falls to the level of the dumbest competitor...

GB

[Georgeablelovehowindia]

The McDonnell Douglas Corporation began on 28th April 1967.

The British Airways DC-10 Series 30s, inherited from BCAL of course, were CAT111A certified with auto go-around.

The training captain who did my base training on the DC-10 had considerable experience on the TriStar too, from its early days with BEA. He had the greatest respect for both types. One thing he did say on the handling was with regard to tail-scrapes. Quite easily done on the TriStar, apparently, much more difficult on the DC-10.

[Jet_A_Knight]

Did they not have a Gust Load Alleviation/Turbulence Damping system of sorts?

First of a kind, I believe.

[skippiebg]

Jet_A_, you mean TriStar, I assume. Its gust load alleviation's what this thread's all about... :) Not a turbulence damper "pax for the use of", more a way of adding span (to cut induced drag) without adding structural beef-up. Seems to have worked despite my (admittedly layman's) misgivings...

[Graybeard]

Cat IIIa in the DC-10 is a long way short of Cat IIIc in the Tri-Star. Even the MD-80, and maybe some 727 were Cat IIIa, but fail passive, instead of fail active.

The L-1011 always drew notice, due to its high deck angle on final approach. I can see where a tail scrape might be more likely. How did its approach speeds compare to the DC-10?

GB

[411A]

Standard deck angle on approach for the TriStar is 7.5 degrees, at all weights.
During the flare, the deck angle should not normally exceed 10 degrees.
If it gets to 13.5, the tail skid will scrape.
The -500 does not have a tail skid, as its shorter aft fuselage would seemingly eliminate the need.
Having said this, I do know of one -500 that had a tail scrape upon takeoff (would you believe) at BOM some years ago.
When the aeroplane landed at AMS, the damage (#2 thrust reverser and drain masts) was noticed, and the Captain, who was recently hired, disappeared, never to be seen again, at least at the respective airline.
And, good riddance, as he was a well known troublemaker at another carrier.

[glhcarl]

I worked a TWA TriStar tail strike at JFK, where the leading edge slat asymmetery brake experienced an overspeed trip and the crew continued to to carry out a full flap no slat landing. The first part of the aircraft to contact the runway was the translating cowl of the No. 2 engine. The deck angle in that case was in excess of 15 degrees. My experience of this, and several other tail strikes, is that the retractable tail skid (bumper) actually causes addtional damage rather than protecting the aft body.

[fergineer]

Hi Hoppy,

Nice to hear you again......Still working hard then in Basle.

GLH....The short body -500 did not have a tail skid and trust me they did get damage when you hit the tail!!!!!!! I know I was there!!!!!!On the last one before the Airforce one just recently.

[glhcarl]

fergineer,

I didn't say the -500 had a tail skid, I said that when the tail skid took a good hit there was usually damage to skid mounting structure. I was on the L-1011 program at Lockheed for over 30 years the last 20 in customer support, including a couple of years with the RAF as their in house technical rep. So I think I know which models have tail skids and which ones don't.