MD11.

[Desk Driver]

Can anyone tell me why the MD11 did not prove more popular with airlines. I can only think it was because it's got 3 motors and not 2 as the fashion seems to be at the moment.

Thanks in advance.



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You fly em we'll fill em!

[criticalmass]

Desk Driver,

The MD-11 failed to meet the specified range and fuel consumption figures MD were quoting. Several customers were pretty ticked with this and MD went into a program intended to improve the aerodynamics (principally by taking measures for drag reduction) and to improve range. In this they were only partly successful.

I'll try to get more details from my reference library shortly but that's about the gist of the problem. Pity in a way, it made quite a good freighter but even that comes to an end (I think) at the end of this year when the MD-11F line at Boeing closes down.

Fedex have bought up a whole lot of ex-United DC-10-10s and Boeing are converting them to a 2-crew glass cockpit. These hulls will probably clock up near 50 years of flying by the time they go to scrap - they may even outlast some MD-11Fs. MD always did build a strong airframe!

[Desk Driver]

Thanks for that C-Mass. Anymore info would be appreciated. I flew on a MD11 the other day and I thought it was a great aircraft.
I imagine as the get older and the Lease rates fall that they would drift into the Charter Market like the Tristar did. Thats assuming they're not all converted to Frieghters before hand of course

[Jim lovell]

There are many reasons behind the MD-11's downfall. The main factor being the lack of range that the airplane possesed. McDonnell Douglas promised that the aircraft could do X amount of nm with X amount of cargo/pax on board when in fact with a full payload the MD-11 could do nowhere near this range. The original launch customer was American Airlines and they themselves were very disapointed with the aircrafts lack of range. There were other reasons like instability within the company itself(at this stage McDonnell Douglas were struggling to stay in the competition with Boeing- the new 777 with only 2 engines and a ranger than the MD-11, and also the Airbus A330 and A340- both of which were in fact cheaper to run and maintain than the MD-11 was.) With the A330/A340 and 777 well-established, there appeared to be no room for a third entry. Despite it's problem with range the MD-11 is apparently a "pilot's airplane" in that it requires a lot of pilot input to operate efficiently.

[criticalmass]

Desk Driver,

My references tell me the following:-

Long range performance of the MD-11 left much to be desired. Both engine manufacturers (GE and P&W) had been "optimistic" in their performance figures when in fact neither engine would deliver the fuel consumption required. The initial PW4460 fuel burn was 6.7 to 8.4% above that specified in the contract, the GE CF6-80C2D1F engines were 4.5 to 5.3% above specification.

The engine manufacturers embarked on product-improvement programs, and MD did likewise in an effort to squeeze a few hundred more miles out of the airframe. The 3-point PIP (performance improvement program) addressed the issues of drag, fuel and weight.

The A-1 PIP saw a 0.1% reduction in drag by adding splitter-plates at the trailing edge of the wing. Later PIPs (1993) achieved a 1.5& drag reduction as well as a 100nm range imrovement, or a 2,5000lb payload improvement. Phase II saw the ailerons drooped by 3 degrees in cruise to improve spanwise loading. This also involved adding slat seals to the outer slat segments.

A further PIP (A-1 Package 2) saw the wing box structure, leading and trailing edges and undercarriage being beefed up to take the increased weight which had now risen from 618,000lbs to 625,000lbs. This increased fuel carrying capacity resulting in a 250nm range improvement or 7,000lb extra payload.

PIP A-1 Package 3 involved re-rigging inboard and outboard ailerons so they drooped for takeoff and assisted takeoff performance at high gross weights. Phase IIIA of the PIP saw some aerodynamic improvements which resulted in a further 1% drag reduction, mainly by very minor changes such as a pylon fillet, seals around the ailerons and a windshield fairing.

Phase IIIB in late 1994 resulted in a drag reduction of a further 1.5% and featured an increase in the diameter of the No.2 engine intake, one of the few non-retrofittable modifications.

In Feb 1995 the fourth phase of PIP was undertaken, wringing out a further 1.2% reduction in drag. This included re-rigging the elevator, wing and undercarriage seals and redesigning the flap hinge-fairings. All in all the total performance increase was about 8% and it restored the range to 7,000 miles with 298 pax. Additional modifications included eother extended standard fuel-tanks or modular add-on tanks in the cargo bay.

P&W and GE had not been idle, their efforts achieveing fuel burn improvements of up to 3% with an estimated saving per year of about $300,000 per aircraft.

To sum it up, a case of promising too much whilst delivering too little, then a hell of a lot of tweaking to achieve the promises, which didn't in fact occur in toto. What kept the MD-11 line going was the fact that it made a damn fine freight aircraft, second only to the 747-400F. The last MD-11s will almost certainly be freighters and they may well see 50 years, along with their (former dc-10) MD-10F predecessors. Fedex will almost certainly end up as the largest operator of the MD trijets in the world.

Hope this answers your query. Most of the info comes from "Douglas Jetliners" by Guy Norris & Mark Wagner. I bought a copy in Winnipeg last year. Highly recommended for any Douglas/MD enthusiast.

[Desk Driver]

Thank you all for the valuable info!


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You fly em we'll fill em!

[Old Dog]

criticalmass, I must confess that I am not aware GE engines was available for MD11. GE was available on the DC-10, but not for MD-11. I may be wrong here.

IMHO, GE engines would have put the MD-11 in better picture.

[static]

klm flies MD-11`s with GE engines.