tristar flare

[mstram]

Watching an L1011 Tristar land, it seems to have quite a nose high attitude. With the
'extra' engine on the tail, I would think that if anything it would be 'tail heavy' and need *less* flare.

Why so high a nose attitude ?

Mike

[criticalmass]

It's not a function of weight distribution, it's a function of the angle of attack required to arrest the rate of descent and place a heavy jet positively on the runway without placing too much vertical loading on undercarriage members.

Watch a DC-10 landing, it wil look pretty much the same, as will an MD-11 or just about any heavy jet of about 767 size or larger. Even the smaller jets (727, 737, DC-9 and variants, 757 etc) still have noticeable flare.

Spare a thought for the pilot-in-command who exercises the judgement to carry out this manoeuvre and the judgement and skill required. Admirable stuff and for airplane buffs, a pleasure to watch.

[mstram]

I realize that all planes need to flare while landing, from what I've observed :

737 / lear / KingAir - 'barely' .. almost flown horizontally on. Approx 5deg deck angle ?

767 / 747 - approx 10 deg ?

L1011 - 20-30 deg ???

Just wonder what is different about the aerodynamics of the '1011 ?

Mike

[411A]

On the L1011, the normal deck angle is 7 degrees during the approach and ten degrees in the flare, and any more than 13 degrees and the risk of a tailscrape is apparent.

[mstram]

My 'angles' were strictly from a 'non-jet-pilot (obviously) plane-watcher-on-the ground' *guesstimate*

Does the L10 fly that much slower on landing that it needs so much more flare ?

Or is it all an optical illusion ? ;)

Mike

[Open Climb]

The approach- and landing speeds on the L10 are similar to any other same-sized jet, but there is one feature on the aircraft that's different from the others, the DLC.

DLC (direct lift control) is a system that keeps the attitude of the aircraft almost constant during approach. By pushing or pulling the yoke the spoilers are activated to accomplish the required shift in vertical speed while the attitude doesn't change that much. It's a great system that's also used on the space shuttle.

Feels kinda strange at first, but once you get used to it it works great. Nice airplane, the L-1011......

[wysiwyg]

Wasn't DLC originally conceived by Lockheed for the Starfighter as a means of allowing the guns to stay pointing at the target while the aircraft manoeuvred before using the technology in the Tristar (without guns!)?

[L1011effoh]

DLC was fitted to reduce landing dispersion in autoland - the TriStar was the first big widebody to have Cat3b zero DH certification. However, the DLC didn't make much difference to the autoland, it just used to land in the same place time after time after time. Plus I believe that Lockheed kept a patent on it so that the others couldn't use it on their planes.

Nice system, but it only comes into operation with landing flap so not much use for fast jets - plus because it uses the spoilers, the fast jet would be burning energy. The Harrier can use the VIFFing (vectoring in forward flight)for pointing, but this too burns energy which is not necessarily ideal in combat.

There were lots of other nice features too.

By the way, the TriStar - 500s would have a higher pitch attitude, about 7.5deg down the ILS slope, and slightly less chance of dinging the tail on the shorter fuselage.

[canadair]

DLC...yes good system, when associated with the autoland, which could so consistently do it better than me! in particular at light weights. although I came to the conclusion after being off the a/c for a while then back on it that DLC was not really nessesary when hand flying, just made the nose hunt up and down at flap 33, ( I know it was me not the DLC, but it was the contributing factor.
Here is a completely hypothetical ? as of course there is a limitation of no speedbrake and flap, but IF the speedbrakes are still deployed at selection of flap 33, ( DLC range) will the boards retract to the 7 degree null position, then modulate the normal 7 up, 7 down, or stay out with an alarming descent rate? one to try in the sim of course only!always wondered, never got around to trying in the sim. :)

[GlueBall]

Upon selection of Flaps 33, extended speed brakes outside DLC range automatically move into the DLC range.

As to "scraping the tail:" There is a tail skid that extends with gear down selection. :cool:

[411A]

Actuallty GlueBall, the tail skid is not fitted to the short body -500 model. AND, if you should have the speed brakes selected with flaps,....have a look at the AFM and note that Lockheed says ....."Not recommended". They should know...unless it's a Brit operation, and then they make up their own rules....very bad idea! :rolleyes:

[Spencer the Rover]

The config warning would be getting right on your nerves before you got to flap 33 dont you think?

[Kerosene Kraut]

If you're out for strange looking alphas take a look at B-52 @ t/o and ldg.

[GlueBall]

Spence:
No config warning if speedbrakes are used with flaps. However, as 411A had mentioned, Lockheed does not recommend use of speedbrakes with flaps. Nevertheless, it's not a limitation and some operators allow speedbrake selection, but only within the DLC range.
As to any possibility of a -500 tail scrape; must be a real acrobat at the controls.
It was never a real challenge to fly the TriStar because it's such a ladies' airplane.
:cool:

[scanscanscan]

As a former "lady" fo, my then Captain an ex Uk Queens pilot deployed full speedbrake with full flap to descend and capture the descent profile.
Seeing and hearing my reaction to this he advised me that this was "acceptable but not recommended" and therefore he could do it.
The rate of descent was more than sufficient to recapture the profile and he said he was glad I learned that night the difference between "forbidden" and "not recommended".
(Bit like changing a RR engine on a 330 I guess)
However I never used this legalise or getout of jail manouver during my command as basically I was not happy with it.
I had been taught in America, and in American technical language terms that "Son,if it aint recommended, you do not stick your dick in there"
Again I guess that as it was my dick that applied with or without some senior blokes OK.
Twenty years on I am still guessing and dicking whenever possible.

[FE Hoppy]

Not 100% sure but the config warnings on some jets are different to others. Most notably the UK jets that also have Recovery Speed Brake instead of high speed stick shake and a different mdlc schedual. As for getting back on the glide I have seen guys manually trim full nose up after 33 flap selected and hold the nose down claiming that this would cause the dlc to put the spoilers further out and thus increase rate of descent. However, as far as I know all this does is move the null point of the trim so the extra effort to hold the nose down would not put the spoilers further out. Any one care to correct me?

[canadair]

well, regards the trim back, push fwd, on the 1011 I believe it does work, I was shown this years ago, and used it on the odd occasion to good effect, and equally it does not work on other types, in particular the 747, so is it a funcion of DLC? well not too sure, but it works, as in the example they keep you high, slow you to 280, but then expect you to cross GWD at 130. Perhaps we fool the system into thinking climb, and bias the spoilers to kill lift, but I am no aerodynamicist, ( not sure I can even spell it)I also agree there is no config warning for flaps and speedbrakes, but I imagine the ROD would be dramatic!either way you have to miss the Tristar, .86 cruise and SO nice to fly. :)

[canadair]

OK before anyone says, I just reread that, and while I have definately done just that, trim back, push full fwd, it would have had nothing to do with DLC, cause at 280 and dec to 130 we were CLEAN!! sorry tired, just back off a trip...
still the process worked, so I have no idea what contributes to it, maybe the flying stab, as opposed to an elevator, stab config.
Hey, I said I was no aerodynamisyst!!