Aircanada014 From Canada, joined Oct 2005, 1282 posts, RR: 0 Posted (1 month 2 weeks 6 days 21 hours ago) and read 2388 times:
Hello all I've done a search but can't seem to find it. I was just wondering after browsing through pictures of Air Canada L1011s and CP DC10s, why did McDonnell Douglas decided to add 3rd undercarriage landing gear and Lockheed didn't with their L1011s? Whats the purpose of having a 3rd one on DC10 and not on L1011? You figure they are very identical in size and shapes although DC10 slightly bigger and maybe heavier, they both have 3rd engine mount at the rear.
ArmitageShanks From United Kingdom (England), joined Dec 2003, 3085 posts, RR: 20 Reply 1, posted (1 month 2 weeks 6 days 21 hours ago) and read 2376 times:
From what I've heard its all about weight. I think they could have MEL'd the center gear on some missions.
MSPNWA From United States, joined Apr 2009, 305 posts, RR: 0 Reply 3, posted (1 month 2 weeks 6 days 20 hours ago) and read 2357 times:
The third main leg was added on DC-10-30/40 and subsequent MD-11 aircraft. The longer-ranged DC-10-30/40 was heavier than the DC-10-10/15, so it need that extra weight distribution.
All models of the L-1011 fall short of the DC-10-30/40's MTOW, so it must not have needed the third gear leg.
CanadianNorth From Canada, joined Aug 2002, 3212 posts, RR: 16 Reply 4, posted (1 month 2 weeks 6 days 20 hours ago) and read 2349 times:
Basically at the start both the L1011 and DC-10 were designed to be more as large medium range jets. The weights necessary to carry out these missions only required the standard 8 main wheels. However, as time went on airlines wanted to use their smaller wide-bodies (compared to the 747) on long-haul routes as well. The added range was accomplished in two ways.
Douglas decided to basically leave the aircraft in its original form, but up the weights and increase fuel capacity, which thus required their new -30s and -40s to have an extra pair of wheels installed to support said weight. Lockheed on the other hand, decided instead of adding fuel they'd shrink the airplane into the L1011 series 500. Because any added fuel/structure/etc was compensated for via having a smaller fuselage instead of significantly higher weights, the original 8 main wheels remained sufficient.
Quoting ArmitageShanks (Reply 1): I think they could have MEL'd the center gear on some missions.
Can't say for sure, but I also remember reading somewhere that if you limited the max weights to below certain numbers, you could send a DC-10 on its way without use of the centre main wheels.
TristarSteve From Sweden, joined Nov 2005, 2838 posts, RR: 23 Reply 6, posted (1 month 2 weeks 6 days 16 hours ago) and read 2295 times:
Quoting CanadianNorth (Reply 4): Can't say for sure, but I also remember reading somewhere that if you limited the max weights to below certain numbers, you could send a DC-10 on its way without use of the centre main wheels.
Yes, friend of mine was in Sanaa (Yemen) with a BA DC10 with a wheel change required.
He had to take a wheel from the centre gear to use on a wing gear, then retracted the centre gear with the u/s wheel fitted to get home to LGW.
747classic From Netherlands, joined Aug 2009, 257 posts, RR: 1 Reply 7, posted (1 month 2 weeks 6 days 14 hours ago) and read 2259 times:
The DC10-10 (Domestic) was designed from the start to add a center gear for further range (TOW) increase. In the later DC10-30/40 International this range increase was effectuated. The DC10-15 was a hybrid hot/high variant (Mexicana, Air Mexico) with the CF6-50 engines of the -30 and the fuselage of the -10, with no center gear.
However the L-1011 was designed as a pure domestic wide body aircraft. Only after a very costly redesign it would have been possible to add a center gear. This inability to increase the TOW to become a real long range wide body aircraft, plus the limited engine choice (only RR, no American engine was certified) led to loosing the competition with the DC10, despite the fact that it was IMO technical more advanced than the DC10.
The range increase was at last produced via a fuselage shrink and a somewhat larger wingspan, in the L-1011-500 series. After only 50 dash 500 aircraft were produced the production was halted, after heavy financial losses and finally resulting in the total stop of civil airliner production by Lockheed.
Western727 From United States, joined Jan 2007, 249 posts, RR: 2 Reply 8, posted (1 month 2 weeks 6 days 13 hours ago) and read 2229 times:
Quoting CosmicCruiser (Reply 5): Yes the center gear can be deferred. You do take a huge weight penalty. I flew one MD-11 flight with the center gr. up.
Figures. Out of curiosity can you recall what the penalty is, assuming one starts out at MTOW?
And while some of us are aware of AA's action years ago to remove the center gear from some of its DC-10-30s, this was a "permanent" thing so I'm curious to know why the center main bogey was up on that MD-11 flight you flew...was it MELed or otherwise? Thanks in advance.
Western727 From United States, joined Jan 2007, 249 posts, RR: 2 Reply 9, posted (1 month 2 weeks 6 days 12 hours ago) and read 2225 times:
Quoting TristarSteve (Reply 6): then retracted the centre gear with the u/s wheel fitted to get home to LGW.
Fascinating. I presume it's relatively easy to do this while on the ground? After all, the center main bogey's "main stem/shaft" (forgive me for I cannot recall the proper label) is angled somewhat forward, like the forward bogey, IIRC.
Further, if the DC-10/MD-11 is, in theory, at MTOW (with the no-center-bogey weight penalty applied) is any special action required to safely retract the center bogey while on the ground?
747classic From Netherlands, joined Aug 2009, 257 posts, RR: 1 Reply 11, posted (1 month 2 weeks 6 days 10 hours ago) and read 2169 times:
Quoting Western727 (Reply 8): Figures. Out of curiosity can you recall what the penalty is, assuming one starts out at MTOW?
All relevant info about TOW,ZFW and LW penalties, with center gear retracted, for all variants of the DC10 and MD 11 aircraft are found in the following PDF file :
L-1011-250 and 500's have a MTOW of 515,000 lbs and the RAF L-1011-500's are certified to 540,000 lbs. with the same basic landing gear installed on the domestic L-1011-1's.
Quoting 747classic (Reply 7): However the L-1011 was designed as a pure domestic wide body aircraft. Only after a very costly redesign it would have been possible to add a center gear.
Lockheed never considered a "center gear" their high gross weight designs used a six (6) wheel truck.
Thank you both. That's a larger penalty that I had surmised and interestingly the other center-gear variants (DC-10-30/40) have significantly lesser penalties.
747classic From Netherlands, joined Aug 2009, 257 posts, RR: 1 Reply 14, posted (1 month 2 weeks 6 days 8 hours ago) and read 2120 times:
Quoting 474218 (Reply 12): Lockheed never considered a "center gear" their high gross weight designs used a six (6) wheel truck
That's correct.
I stated only that adding a center gear would have needed a very costly redesign.
Lockheed proposed the L-1011-8 in which six-wheel main undercarriage bogies (trucks) were to replace the four wheel units of the original Tristar, and the wing was to be redesigned to house the larger undercarriage and improve performance at higher weights.
The price of the L-1011-8, however, exceeded that of the more straightforward long range versions of the DC10 (the series 30 and 40) and Lockheed could not find a launching customer for this version.
The whole technical and commercial story of the L-1011 is perfectly described in the book :
Lockheed Aircraft since 1913, by René J. Francillon ISBN 0-87021-897-2
Naval Institute Press, Annapolis, Maryland 21402.
474218 From United States, joined Oct 2005, 3827 posts, RR: 1 Reply 15, posted (1 month 2 weeks 6 days 8 hours ago) and read 2098 times:
Quoting 747classic (Reply 14): Lockheed proposed the L-1011-8 in which six-wheel main undercarriage bogies were to replace the four wheel units of the original Tristar, and the wing was to be redesigned to house the larger undercarriage and improve performance at higher weights.
There was no need to re-design the wing for the 8 wheel truck as only the landing gear strut retracts into the L-1011 wing. The truck retracts into the fuselage.
Spacepope From Vatican City State (Holy See), joined Dec 1999, 1962 posts, RR: 1 Reply 16, posted (1 month 2 weeks 6 days 2 hours ago) and read 1988 times:
Ex52tech From United States, joined Dec 2006, 499 posts, RR: 2 Reply 17, posted (1 month 2 weeks 5 days 23 hours ago) and read 1938 times:
Quoting 474218 (Reply 12): RAF L-1011-500's are certified to 540,000 lbs. with the same basic landing gear installed on the domestic L-1011-1's.
Which is a higher MTOW than the DC10-40's had at 535,000 lbs. Thing to remember is that 10 brakes are better than 8. Not sure what JAL -40's MTOW was though.
Quoting Western727 (Reply 9): is any special action required to safely retract the center bogey while on the ground?
It had it's own guarded retract switch, so it was a simple operation. One would want to ensure that the parking brake was not set when attempting this operation. The center gear was the reason that the parking brake had to be off while refueling the -30/-40.
"Saddest thing I ever witnessed....an airplane being scrapped"
Viscount724 From Switzerland, joined Oct 2006, 10996 posts, RR: 13 Reply 18, posted (1 month 2 weeks 5 days 23 hours ago) and read 1928 times:
Quoting Spacepope (Reply 16): DC-10-40 without extended center gear. Photo says no passengers aboard at the time.
It was my understanding that when JL used their DC-10-40s on shorthaul domestic and regional routes they sometimes kept the center gear retracted. Note following photos (coincidentally, all of the same aircraft).
747classic From Netherlands, joined Aug 2009, 257 posts, RR: 1 Reply 19, posted (1 month 2 weeks 5 days 11 hours ago) and read 1830 times:
Quoting Ex52tech (Reply 17): It had it's own guarded retract switch, so it was a simple operation. One would want to ensure that the parking brake was not set when attempting this operation.
On following pics are the guarded CTR GEAR switch of the DC10-30 (with chain) and the push button of the MD11 clearly visible at the RH side of the gear lever. Both are marked CTR GEAR NORMAL/UP. Above the gear lever are the four (4) gear down lights (green).
Kimberlyrj From United Kingdom, joined Mar 2008, 298 posts, RR: 1 Reply 21, posted (1 month 2 weeks 5 days 3 hours ago) and read 1723 times:
Quoting Viscount724 (Reply 18): It was my understanding that when JL used their DC-10-40s on shorthaul domestic and regional routes they sometimes kept the center gear retracted. Note following photos (coincidentally, all of the same aircraft).
I can’t recall where I saw it (which magazine or book) but I remember reading that JL removed the centre gear to reduce weight as the aircraft as the aircraft in question would never reach the weight limit which would require the use of the centre gear – as the aircraft was used on short haul ops and carried no were near as much fuel as it was designed for (being the long range 40 series).
Did anyone ever hear/read about this?
KimberlyRJ
Remember being polite costs nothing, even to us cabin crew ;o)
Kimberlyrj From United Kingdom, joined Mar 2008, 298 posts, RR: 1 Reply 24, posted (1 month 2 weeks 4 days 13 hours ago) and read 1589 times:
Quoting Western727 (Reply 22): I don't know about JL; that's news to me. AA as I understand it did this with some of its -30s.
Hi
Been looking at the photo database and seen that JL used two sub versions of the DC10-40, I for international and D for domestic.
The I versions had the centre rear landing gear and the D versions had this removed – this is shown when you search the Airlines.net database for JL DC10-40 photos...
Intriguing; thanks for sharing. IIRC, AA had the center gear removed from some of its -30s in their final years because they still had some cycles left on them after many years of high-time cycles. From what I understand AA wanted to wring what cycles they could out of those airframes for its high-density, non-long-range routes.
JarheadK5 From United States, joined Nov 2005, 214 posts, RR: 1 Reply 27, posted (1 month 2 weeks 3 days 4 hours ago) and read 1468 times:
Quoting CosmicCruiser (Reply 5): Yes the center gear can be deferred. You do take a huge weight penalty.
The KC-10 can operate with the center gear retracted as well. It's pretty much only done when sending the aircraft to C-check; no one I've spoken to has ever done it for any other reason. We take a big weight penalty, and there's also a big takeoff-distance penalty, due to the loss of 20% of the aircraft's braking capacity.
N901WA From United States, joined Oct 2009, 38 posts, RR: 0 Reply 28, posted (1 month 2 weeks 2 days ago) and read 1331 times:
Hi, For Western727. When Retracting the Center Gear on the Ground. First you had to deflate the Center Strut, otherwise after the hyd broke the overcenter lock the pressure in the strut would force the strut foward and bend the retract actuator. You dont want to know how I know Then you had to walk the Gear fwd as it went up to get it to fit in the Center Wheel well. Then service the strut so it would stay in the extend postion in the well. It took some time and was same on the 10-30 and MD-11. HTH Darren
Western727 From United States, joined Jan 2007, 249 posts, RR: 2 Reply 29, posted (1 month 2 weeks 1 day 10 hours ago) and read 1239 times:
Quoting N901WA (Reply 28): When Retracting the Center Gear on the Ground.
Thanks, Darren. I had a hard time believing one could just retract the center gear "in a snap" while on the ground, let alone at center-gear-retracted MTOW.
I would've liked to think the center bogey's strut would be somewhat compressed even at "only" 400-some thousand pounds of weight which is the neighborhood of MTOW for all DC-10/MD-11 family models with no center gear in use.
N901WA From United States, joined Oct 2009, 38 posts, RR: 0 Reply 30, posted (1 month 2 weeks 1 day 7 hours ago) and read 1183 times:
Hi Western727, sorry for the late reply. I work the Night shift and just got home. The first time it took about 2 hours and 2 guys, but after that 2 guys 1 hour to stow and defer the Center strut. HTH Darren
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The center gear was the reason that the parking brake had to be off while refueling the -30/-40.
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Then you had to walk the Gear fwd as it went up to get it to fit in the Center Wheel well. Then service the strut so it would stay in the extend postion in the well. It took some time and was same on the 10-30 and MD-11. HTH Darren
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