Ultimate DC-10/MD-11 Guide

Well, the variants of the DC-10 family have such overlapping “minor” features that it’s very difficult to define any particular series by a particular set of features (asides from the really obvious ones like presence of a center gear). The best solution I can think of is to introduce the minor physical variations first that show up quite early, then go series by series as they introduce the features, roughly chronologically. And mix in the later minor variations as they come up. Unlike many other airliners, for the DC-10 a change might be introduced, yet not become “standard” for several more years. You can look at a picture of the Long Beach flightline from the 80’s, and see DC-10-30s that are built the same as the earliest 1970’s orders, right next to ones incorporating every latest feature. The MD-11 is much easier, for almost every new feature became standard the moment they became available.

Nomenclature note:  Whenever “-10” appears I mean a particular series, the DC-10-10, never the DC-10 family as a whole.

Aft Wing/Body Fairing–Port Side

First of the minor changes, but also the largest and easiest to identify of the “minor” changes. The later/larger style eventually became the most common style, regardless of series. All -30’s have this style. The early style was of course standard from the very first DC-10 built. The later style was introduced on the DC-10-20 prototype.

The early style, which is found only on DC-10-10s (but not all -10s) ends approximately 6 windows forward of the aft door. The later, larger style extends further aft, all the way to the end of the window-line.

Early style on the very first DC-10 itself, N101AA.

Later style on a late-build DC-10-10, N914WA.

Bulk Cargo Door Location/Design–Port Side

This segues in nicely from the previous one. In the two photos above, the bulk cargo door is directly under the last 3 windows. That of course means on those DC-10s with the later fairings and that door, that the fairing overlaps the door. However, later on the bulk cargo door was completely redesigned, (it’s slimmer and more curved) and moved aft behind the aft passenger door. This was introduced on the first DC-10-30, PH-DTA. See here:

Yes, this is an MD-11, but they have the exact same shape/size/location for their bulk cargo door, which is one less thing to write about in the second half of this guide.

Nearly all -30s have the combination of the later/larger aft wing/body fairing and the moved-aft bulk door—only -30CFs and -30Fs have the forward bulk door location.
No DC-10 has the earlier wing/body fairing and the moved-aft bulk door.

Aft Cargo Door and Aft Wing/Body Fairing–Starboard Side

This isn’t really a separate variation, but I figured I’d include it nonetheless. Anyways, the aft cargo door is the same on all DC-10s, but since the wing/body fairing can differ, it may or may not be covered by the fairing. If the fairing is short, it ends just in front of the aft cargo door. If the fairing is long, it almost completely covers the door.

Short fairing:

Long fairing:

Engines

Quite a few variations, and it’s probably better to put them here than with each series. A key thing to look for to distinguish the engines on a DC-10, is where the end of the hot section is, in relation to the rear edge of the #2 pylon. All photos are of the #2 engine. Engines change, and can be mixed early/late. All that matters is that all 3 are the same model.

Early CF6-6 on DC-10-10s

The only DC-10-10s with core/hot-section thrust reversers. The core section reverses by having the large square-shaped section (which is actually a sleeve over the hot-section’s own reverser cascade array) slide back, exposing the cascades. The cascades then split left/right and rotate about 45 degrees, to intersect the core’s exhaust flow. (Picture of open core reverser to be added when I get around to scanning the photo)

Early CF6-50 on a DC-10-30

Actually looks fairly similar to the early CF6-6, but a different hot-section reverser. Very short, stubby exhaust spike

Yes, the early DC-10-30s had hot-section reversers.

Late CF-6-50 on a DC-10-30/DC-10-15

Looks very much like the later CF-6-6 on a DC-10-10. However, it lacks the little probe on the end of the exhaust spike. Also, the spike itself extends past rear edge of the pylon. A -10’s CF6-6 has the spike end well before the pylon edge, and only the probe extends to the rear of the pylon. Hot section extends SLIGHTLY further aft than a CF6-6.

Late CF6-50 on left, late CF6-6 on right for comparison.

Also note that the bottom of the pylon on the CF6-50 angles down, the bottom of the pylon of the CF6-6 is horizontal.

JT9D-20 on DC-10-40 (NW)

Unique to NW’s DC-10-40s. Only on NW’s -40s, on all of NW’s -40s.
Fairly similar to late CF6s, but with the hot section ending only a little bit ahead of the pylon edge, and having the largest and pointiest exhaust spike of all DC-10s. Notably larger nacelles on the wings than other DC-10 engines.

JT9D-59 on DC-10-40 (JAL)

Easiest to spot!  No exhaust spike at all. Hot section exactly as long as pylon.

Well, that’s enough details to get started, more fairing variations ahead though.

Early DC-10-10

Well, there’s not much to say, seeing as how it’s the “default” DC-10. Basically, it has CF6-6s, the short aft wing/body fairing, and the forward bulk cargo door. It also lacks every other feature that’ll be introduced later on in the guide. This picture of N907WA is used because it shows the distinct LACK of things which will be pointed out later, and is a good picture to refer back to for a “basic” DC-10.

DC-10-20. AKA DC-10-40, NW.

First DC-10 variation. Has JT9D-20 engines (-20 engines for the -20 DC-10, see?)   Introduces the longer aft wing/body fairing. (See above, way above)  All -20s have it. Still has original bulk cargo door.    Also introduces the 2-wheel center main gear. Also introduces the 10-foot greater wingspan. The greater wingspan is very difficult to see, since it’s as if the entire wing was simply stretched at the tip. There’s no obvious change. Sweep and taper are unchanged from the -10’s wing. (No kink, unlike most every other wing change in airliner history). Tip looks the same because the outboard aileron was extended as well. The only way to really tell is to get a -10 and a -20/30/40 side-by side to compare aileron span. Will add a wingtip-comparison photo if I ever find a good one.

Also very notable for having a bulged #2 intake:

The legend is that NW didn’t want their plane to seem less advanced than the -30, so they got MDC to change the name to the series 40, and that’s what it is known as today.

Early DC-10-30

Basically a DC-10-20, but with CF6-50 engines, no intake bulge, and the new bulk cargo door location.

More variations, DC-10-10/30/40

As if it wasn’t complicated before, now it gets much, much worse. Here is where we start seeing new things introduced “unevenly”, and overlapping with other variations. And because the easy-to-spot thing came last, we’ll have to do the hard ones first.

Horizontal Stabilizer/Fuselage Fairing, and Horizontal Stabilizer Leading Edge Root Extension

No, it’s not an F/A-18, but many DC-10s do have LERXs on their stabs. This is a two-for-one deal, and actually three-for-one when we get to the next one. Description first, then pictures. The original DC-10 h.stab has a perfectly straight leading edge, and is attached to a large (but subtle) fairing on the rear fuselage. This fairing surrounds the entire h.stab root. It is not large enough to reach the aft door. Look at the AA DC-10s above(-30) and below(-10), the grey stab fairing is quite obvious, and just touches the end of the blue stripe. Also note the straight leading edge of the h.stab itself. That’s the early DC-10 stab/fairing combination.
Here’s a nice big close-up:

Later, McDonnell Douglas improved the area, and added a fairing to the leading edge of the stabilizer itself, at the root. They also greatly enlarged the stab/fuselage fairing. The leading edge of the h.stab is no longer straight, but curves forward at the root. The stab/fuselage fairing is now large enough to almost touch the aft door, and the apex of the fairing is now further up and more pointed, near the top of the aft door. See here:

Larger fairing, more pointed and with the apex moved up, h.stab now has a curved fairing at the root leading edge. More photos, showing side-by-side comparisons (these are all -30’s, with the plane closer to the camera having the h.stab area modifications):

I like this photo because Iberia’s scheme works so well—on the original stab/fuselage fairing (background), it only extends to the TRAILING edge of the flag, but on the later fairing (foreground), it extends to the LEADING edge of the flag. (it is difficult to see the leading edge of the stab/fuselage fairing due to the striping, but it is visible on both planes)  

Vertical Stabilizer Root Fairing

This is part of the same modification package as the h.stab fairings. Look at the closer of the two Iberia DC-10s above. See the little fairing at the base of the leading edge of the v.stab? (it’s easy to see its exact shape because of dirt). That is another fairing McDonnell Douglas added on. This and the h.stab modifications always go together, you never get one without the other. (And since the h.stab is actually two things, it’s these three things always go together). Look 2 pictures up and compare the NW DC-10 v.stabs—-the fairing is clean, but it’s very easy to see how the one in the background doesn’t have the fairing at all, and there’s a sharp angle where the fin meets the intake.

So those three things (h.stab/fuselage fairing enlargement, h.stab root leading edge fairing, and v.stab root leading edge fairing) all go together as one single package/combination really, and were the first thing introduced later on in the DC-10-30 program. However, they were definitely OPTIONS. Even some of the very last DC-10’s built in 1988/1989 did not have these. Popular options (who wouldn’t want less drag?) but options nonetheless.

Forward Wing/Body Fairing

Look way back up to the DC-10-10 and DC-10-30 main pictures. See how the leading edge of the wing attaches directly to the fuselage, with practically no fairing at all? That’s how the early ones had it. Later (after the three things just above were introduced) a very large forward wing/body fairing was added on. Really obvious when you look for it:

Really easy to spot on any DC-10 with a bare-metal belly:

Now, this was also an option, but not quite as common as the previous 3-pack. However, this is never installed by itself. It is always installed with (or after) the 3-pack of stab fairings. There’s some DC-10s with none of the fairings, a few with only the stab fairings, and a lot with all of the fairings. But none have *only* the wing/body leading edge fairing. KC-10s always have all of the fairings, FYI.

Late DC-10-30/Retrofits

There’s really no definite standard for these. Basically, any DC-10 built after these options became available, may or may not have them. And it may have the early or the late style CF6-50 engine. Just about every combination of engines and fairings exist. (with the stipulation that you can only have the forward wing/body fairing if you also have the stab fairing).

And most importantly–you can retrofit any of these later on. KLM, having the first DC-10-30s built, later took them in and got all of the fairings added on later. Here’s PH-DTC, as built and in the 90’s:

You can easily see the wing/body fairing has been added, as well as the v.stab fairing. Less obvious is the h.stab modification, but it’s there. (You can also see KLM made a slight change to the paint scheme–look at the titles)

Quite a few DC-10-30’s that were built with only the h.stab fairings received the wing/body fairing later. KLM seems to be one of the few airlines to retrofit all of them. Of course, KLM also stretched the humps on most of their 747 fleet.

 No Northwest DC-10-40 ever got any of these fairings, they are all still identical to the first one as built in 1972. JAL also left their planes as delivered, and has quite a mixed fleet, which is our next subject.

DC-10-40D, DC-10-40I (JAL)

Generally identical to NW’s DC-10-40’s, but with JT9D-59 engines and the later bulk cargo door. The early deliveries had none of the optional fairings, the middle ones had only the h.stab fairings, and the last ones had all of them. So if you’re building a model of one, you really need to check EXACTLY what any particular one looks like.

Much like their 747SRs etc, JAL has specially configured DC-10-40s for short-range high-density routes. The DC-10-40D. It is not a factory option, and is nothing more than having the center gear removed, as it will never be used since the plane is never loaded with much fuel, and thus doesn’t need the support. It’s pointless to drag around a several-thousand pound gear if you’re never going to use it. The “normal” DC-10-40 for JAL is the DC-10-40I, I for International. JAL switches around the “D”s and “I”s often, to average out hours vs. cycles. All you have to do is re-install the center gear. (And rearrange the seats). And since they swap them around, a -40D and a -40I may have any arrangement of fairings. This leads me to believe the fairings don’t have a very large effect, otherwise preference would be given to having only the later ones with all the fairings on the long-range routes.

Late DC-10-10/-10CF

There are only two variations of DC-10-10s:  the earliest as built ones as described way above, and later ones with the later aft wing/body fairing, the aft bulk cargo door, and all the fairing packages. There simply are not any “inbetween” ones like is so common on -30s and -40s. And there is no overlap–N132AA was the last “early” -10, and looks identical to the first DC-10 ever built as does every -10 before. The next -10 built was N1838U, and it has every fairing/option the DC-10 family has ever introduced as does every -10 after it.    DC-10-10CFs add a forward cargo door, otherwise identical to a late DC-10-10. I also cannot find any early DC-10 that had anything retrofitted.

Here’s N914WA, a late DC-10-10. See how similar it looks to a DC-10-30 with all the options.

DC-10-30CF/-30F

DC-10-30CFs are identical to a late -30 with all the options, except for having a forward cargo door, and for some reason having the earlier bulk cargo door location. DC-10-30Fs are identical to -30CFs except they have the later bulk cargo door location and were built without passenger windows. Note:  this only applies to DC-10s built as CF/Fs, FedEx’s giant fleet of cargo conversions can be almost anything.

DC-10-15

Actually among the last types of DC-10 developed. Basically a DC-10-10 with a -30’s engines. Identical to a late DC-10-10, but with later style of CF6-50 engines. Only 7 built.

MD-10-10, MD-10-30

A DC-10-10 or DC-10-30 (respectively) retrofitted with an MD-11’s cockpit. If you want to know more, PM NightFlyer.

Well, that’s it for the DC-10 guide (until I get more pics, or find something I forgot). On to the ultimate (literally) tri-jet, the MD-11.

MD-11, early

Internally, the main change is the all-new glass cockpit. But these guides are always about the outside, so I’ll skip all the “invisible” changes like new light-weight alloys, etc. FYI, there were exactly 200 MD-11s built, compared to 386 DC-10s and 60 KC-10s.

For many things, you can generally assume it is similar to a late DC-10-30—-it has the fairing at the base of the v.stab, it has the large fairing at the leading edge of the wing root, it has a center 2-wheel main gear, the aft bulk cargo door, the extended aft wing/body fairing, and it has the extended wings/ailerons. Note: because the aft fuselage was stretched 6 frames, the wing body fairing does end 6 windows ahead of the rear door, same as a early DC-10-10. But it’s still the longer one of the DC-10-30. (if it was the short one like on early DC-10-10’s, then it’d end 12 windows ahead of the rear door)

Externally, the biggest change is the fuselage stretch. 5 frames forward of the wing, 6 frames aft. 8ft, 4in and 10ft, 2in to be precise. 18ft 6in total *cabin* stretch. MD-11s also have a new flat tailcone like an MD-87’s, which adds an additional 3ft, 5 in to the fuselage length, for a grand total of a 21ft, 11in longer fuselage than a DC-10.

Next is the all-new horizontal stabilizer. 69% as large as a DC-10’s, but with similar proportions. Has a leading edge fairing at the root just like later DC-10’s. H.stab fairing more similar to the early DC-10’s though, but the rear is quite different. A DC-10’s h.stab/fuselage fairing  tapers both above and below as it heads aft, and comes to a  point in line with the elevator leading edge, and is thus not visible aft of the stab itself. On the MD-11 it narrows but straightens out and extends well past the elevator, ending mere inches from the tailcone itself.

MD-11

DC-10 for comparison:
 

Next, winglets. The MD-11’s wing is basically the same as the DC-10-30’s, just slightly tweaked aerodynamically and now with a lot of composite parts–nothing you can see without slicing it apart to see the airfoil shape or materials. The winglets are simply added on to the wingtip, no changes in span etc asides from that caused by the outward cant of the winglets themselves. Also note the smaller lower winglet, fairly rare as winglets go. It also cants outward. If you look along the upper edge and see how the trailing edge curves outward, you can see the winglet is not “flat” but has the same airfoil shape as a wing. 

MD-11s have new engines, either GE CF6-80C2-D1Fs, or PW4460/PW4462s.

CF6-80C2-D1F (D for Douglas):

PW4460/4462 (they are physically identical):

Note that the GE has a small fairing under the pylon that angles rearwards.

In addition to the new engines, the pylons get some fairings (of course). Right where the leading edge of the pylon meets the underside of the wing, see here:

The slotted vent in the pylon is for bleed-air pre-cooler, BTW.

Finally, the MD-11 has a bugled #2 intake, just like the DC-10-40. It may be a little late to point out now, but on any DC-10/MD-11 with a bugled #2 intake, the back bulges quite a bit too.

That’s your standard MD-11 as built, good from #’s 447 through 556. MD-11 line numbers start right after the DC-10—the last DC-10 was the 446th built (including KC-10s) so the first MD-11 is #447.

PH-KCA, MD-11 #557

KLM’s MD-11’s introduced several new features on the MD-11. The first is the new exhaust spike. This only applies to those with GE engines, but is on every GE-powered MD-11 from this point on. Your standard GE exhaust spike looks like this:

The new bigger, pointier one looks like this:

The new spike does increase the overall length of the plane. An MD-11 with PW engines is 200ft, 11in long. One with the early GE engines is 201ft, 4 in long. One with the later GE engines is 202ft, 2in long. The spike itself is about 20 inches longer than the original. (purely a guesstimate by me). The reason for the new spike is unknown the me–the engines are identical (no mention on the type certificate of any variation) and interchangeable–as time goes by you see more and more planes with mixed spikes, assuming the airline pools engines and types. Alitalia and VARIG are the ones most often seen with a mix of spike types.

PH-KCA was also the first MD-11 to introduce the new aft cargo door (aft cargo door, not aft bulk cargo door).

Here is the standard MD-11 aft cargo door:

Note that it is aft of the wing/body fairing, and taller than it is wide.

The newer style is made wider by being extending it forward, and is partly covered by the wing/body fairing:

This was an option, not standard from this point on. It was however quite popular, especially on cargo-carrying MD-11s.

PH-KCE, MD-11 #575

Only one thing introduced here, but it’s an important one, and probably the least obvious/understood of all MD-11 changes. The new #2 intake. Pics first, then explanation.

Intake on the first 128 MD-11s:

Intake on the other 72 MD-11s:

And a bare DC-10 intake showing the grey banjo frames:

Ok, the main thing to look at is the trailing edge of the intake’s bulge. On the DC-10-40 and early MD-11, the trailing edge of the bulge itself it is perfectly vertical, and the bulge ends right at the base of the leading edge of the v.stab. This is also right where the v.stab fairing is, and is quite visible on the Thai intake just above.

Now, on the later MD-11 intake, the bulge is lengthened and the trailing edge is angled rearwards. This is quite obvious when the light hits it right, as on the KLM intake just above. Look at the AA intake immediately above—see the 4 large grey stripes? Those are the “banjo frames”. They are circular frames that go around the intake, and are the main support for the v.stab as well as the forward mount for the #2 pylon/engine. The front 2 banjo frames are angled, the rear 2 are vertical. The MD-11 has them just the same, but they’re harder to see since no MD-11 has a bare intake.

Anyways, the later-style MD-11 intake bulge has its trailing edge extended and angled to match the forward-most banjo frame. The banjo frames on the picture of the KLM intake are about as visible as an MD-11s can be. You should be able to see that the bulge now goes right up to the forward banjo frame. Here are some photos of KLM’s fleet showing a mix of old and new intakes. (Most airlines have one or the other type, though you’ll often find the last one or two of an order having the new style—Delta has 2 like this)

*All* MD-11’s from PH-KCE on have this new intake. This includes the entire fleet of some airlines, including Lufthansa and Martinair.

HZ-ANA, MD-11 #609

This introduces the easiest to spot difference–new flap-track hinge fairings. All DC-10s, and all MD-11s up to this point have flap hinges like this:

Nice, straight trailing edges. Completely under the wing–unlike most every other Boeing, Airbus, etc you cannot see the flap-tracks from above the wing, and they do no protrude beyond the trailing edge.

However, starting with HZ-ANA, MD-11s got new flap-hinges, but only on the OUTBOARD flaps. See here:

New trailing edges on the flap hinges. Easy to spot from almost any angle.

Here’s 2 of Finnair’s MD-11s, one with and one without the new hinges:

This was the final major external modification done to the MD-11.

MD-11F

Ironically actually the first MD-11 type. MD-11 with a cargo door, no windows, all the standard freighter stuff. Most of the ones after the initial FE order (basically all the ones built after PH-KCA)  have the larger aft lower deck cargo door.

N602FE:

MD-11Combi

Quite rare, only 5 built for Alitalia. Basically an MD-11 with a REAR side cargo door on the main deck. Also has the larger aft cargo door like on KLM’s planes. MD-11Combi’s carry both passengers and cargo simultaneously.

(The large antenna on the roof, a bit behind the titles is a satellite antenna found on many MD-11s)

MD-11CF (Convertible Freighter)

Almost as rare as the Combi, 4 built for Martinair, 2 for World Airways. The CF has a side cargo door at the FRONT of the plane. The CF is noted for being either all-pax or all-cargo. Not both. And it is not a quick-change like some 727s. It is basically converted winter/summer, as it takes several days to do the conversion. (it of course takes longer to re-install the pax equipment than to remove it). Also has the larger lower-deck rear cargo door.

MD-11ER/ERF

Quite rare, the extended-range MD-11 adds a 3,000gal fuel tank in the forward cargo bay. Externally identical to any other MD-11 or MD-11F. 3 ER’s built for VARIG, 2 ERF’s built for World. They do not necessarily have all of the improvements that the latest MD-11’s have.

MD-11 PIP (Performance Improvement Packages)

The MD-11 is probably most famous for not meeting its range/payload guarantees, mainly due to fuel-thirsty engines.  GE and PW could only make marginal improvements, so it was up to MDC to try to make their already-sleek plane even sleeker to cut drag and fuel-burn that way. (Swissair and Delta opted for additional fuel tanks in the cargo bay—more range instantly, but at the expense of payload).

One of the first things done was to add on the trailing-edge-splitter, AKA trailing edge wedge. Basically it makes the trailing edge over most of the wing somewhat blunt instead of paper-thin like most planes. Just add on a thin strip to the very trailing edge. Photo will be added as soon as NightFlyer sends me one. 🙂   (It’s on the vast majority of MD-11’s, but it’s rather subtle so I’m waiting for an ultra up-close photo—but feel free to look at any other pictures, and look for a very thin and long fairing along almost the entire trailing edge)   It’s attached on the underside, and extends just beyond the normal trailing edge.

Most of the other improvements are detailed above, such as the new intake and flap hinges. The ailerons were also programmed to droop in certain flight phases, but that’s not really a physical difference.

Probably the most famous of the PIP improvements is the repositioning of the windshield wipers. Like most planes, the early MD-11’s have their wipers horizontal when they’re not operating:

Later, they switched them to vertical:

Photo credit:  David Hingtgen  🙂

This feature was retrofitted to every MD-11 AFAIK.

Miscellaneous DC-10/MD-11 Things

The unique location of the #2 engine has always presented problems for maintenance. One of the main things is how to change it. To do this, the inboard elevators split in half and the inboard sections can hinge until they are pointing straight down–this allows the engine to fit between the elevators as it is lowered. Also, the tailcone rotates almost 180 degrees until it is entirely underneath the h.stabs, also to make room for the engine. All of this together looks like this:

DC-10 with #2 engine removed. Note the pylon is still there.

(Ignore the 707 engine in the corner.)  Also, the tailcone isn’t COMPLETELY folded under, it can go even further than is shown.

Another thing is the self-contained platform in the tailcone. The upper part of the tailcone unfolds to provide a maintenance stand. You reach it by a small set of stairs that come down from a hatch just in front of the tailcone:

Platform open, stairs extended. MD-11s have this too, though the tailcone opens up differently due to the new shape:

Finally, all DC-10’s and MD-11s have a very small leading edge strake very close to the wingtip, just inboard of the nav light: