The Mighty DC-10

FNG

FNG

New Member
This is for you DC-10 buffs out there (if there is such a thing):

Why don't the manufacturers tack on wings that create more lift? I heard pilots have to rotate across 1300 ft. of runway at a ridiculous AOA just to get airborne. What's the point? It seems rather dangerous to me.
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Thanks in advance for any responses.

-FNG
 
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Why don't the manufacturers tack on wings that create more lift? I heard pilots have to rotate across 1300 ft. of runway at a ridiculous AOA just to get airborne. What's the point? It seems rather dangerous to me.

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Could you be a little more specific? What do you mean when you say, "Pilots have to rotate across 1300 ft of rwy at a ridiculous AOA"?
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Well, I'm certainly no aerodynamics expert, but I think you are referring to the fact that large fast airplanes require more airspeed and runway distance. The reason is because they have a swept back wind design. This design requires more airspeed to create lift. So to answer your question, the reason they don't put wings creating more lift is because of drag. The swept-back design works well with fast moving aircraft because they create less drag when they are moving fast, but the down side is that they require longer takeoff and landing rolls because they do require more airspeed to get enough lift.
 
The wing is what flys.

The fuselage is the metal tube that is bolted to the wing.

So, bolting a new wing to the body is redesigning 80-90% of the plane. Not a small project.

Jet wings are designed to fly at Mach .8 with some modifications that allow them to take off and land at reasonable speeds.
 
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Jet wings are designed to fly at Mach .8 with some modifications that allow them to take off and land at reasonable speeds.

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Unless in my world. You rotate and somewhere around 190+, the jet lifts off.
 
Big wing = citation performance = crustacean speeds = despair
 
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Unless in my world. You rotate and somewhere around 190+, the jet lifts off.

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Sounds like the T-craft I got my float rating in... oh, wait, did you say one hundred ninety?? hmm...
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BTW I love FNGs avtar.
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I've seen guys do that on purpose when showing off, but I don't think that's the case in that picture.
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Unless in my world. You rotate and somewhere around 190+, the jet lifts off.

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Fighters are murder on tires and brakes.

I had a friend who was in an F/A 18 squadron in Iwakuni Japan. He said they saved all thier tires for the whole week. Then on Monday they would have "tire day", everbody in the shop would set aside what ever they were working on. They would replace 20-40 tires in one morning.

Two guys would break them apart.

Four guys would wash the wheel halves off.

One guy would check them for cracks.

Three guys would build up the new wheels with new tires.

Two guys would pressure test them.

One guy would do the paper work.

He said this system was far more efficent, it just took some work convincing the Maint Officer to approve it.
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Most people are shocked by how much air pressure is in an airplane tire. I've forgotten the exact numbers, but it's pretty high.
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IIRC the tire pressure for a F/A 18 tire on carrier ops was over 1500 PSI.
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You will have to bear with me because my technical knowledge of all things aerodynamic is nil.

I heard somewhere on the internet that DC-10/MD-11 pilots basically have to force their planes into the air, and have a greater nose-up angle than most planes when they rotate (which accounts for how high up the plane sits from the ground), and rotate for about four seconds or so ("forcing the plane into the air") before lifting off.

I just think there is something inherently dangerous about a plane that taildrags across 1300 ft of runway, is all. I mean, when you reach rotation speeds you're essentially committed, but if in the heat of passion or impending doom you decide to tap the breaks or steer a bit....
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I didn't consider the relation between larger wings and "crustacean speeds"
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when I penned the question
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Please forgive my newb-ness.

TY,

FNG
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[ QUOTE ]
I heard somewhere on the internet that DC-10/MD-11 pilots basically have to force their planes into the air, and have a greater nose-up angle than most planes when they rotate (which accounts for how high up the plane sits from the ground), and rotate for about four seconds or so ("forcing the plane into the air") before lifting off.


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Okay, first, don't believe everything you read on the Internet.

There is nothing wrong with the design of the DC-10 or MD11. Aeronautical engineers are in a constant battle to optimize lift and speed without increasing weight and drag. They don't just slap a wing on an airplane all willy-nilly and say have at it. There are countless hours of wind tunnel and computer testing to optimize the wing to the aircraft being designed. They've designed a wing to maximize lift at slow speeds and low drag/high efficiency at fast speeds.

Most large jets when properly rotated will "unstick" (meaning their main wheels come off the ground) at around 8 degrees nose up attitude. Over rotating could cause a tail strike (that's a bad thing). It's not unusual for a large jet to roll on the mains for a little while with the nose in the air as it transitions to flight. Initial climb out pitch attitudes are around 15-18 degrees depending upon weight/power.

Pilots will generally rotate (lift the nose) at a rate of 2-3 degrees per second. This requires approximately 3-4 seconds from initial rotation until airborne. 4 seconds while traveling at 150+mph eats up a little bit of rwy. That's probably where you heard the 1300ft remark. Not unusual.

From what I've heard from pilots who have flown both speak of them as being real Cadillacs to fly. A real gentleman's airplane. The pilots don't have to "force it" to do anything.
 
When any airplane rotates on takeoff it takes a moment for the lift to overcome the inertia.

The larger the airplane the more inertia that must be overcome.



I don't know if the DC-10 requires a greater nose up attitude, but it wouldn't be out of the question. Each type of airplanes have their own quirks.

I don't doubt that the DC-10 takes a firm pull to rotate the nose. This may be what you mean by "forcing the plane into the air".




The reason that large jets seem to climb so slow, isn't their rate of climb, it's their foward speed. They are going so fast foward that they doesn't appear to climbing very fast.

I'll just pull a few numbers out of thin air for ilustration. (if any of you heavy equipment operators want to correct me with precise figures, feel free)

Ground speed at take off = 150 mph

Rate of climb = 1500 fpm

150 mph = aprox 2200 fps

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across 1300 ft of runway

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takes less than 1 second.

Durring that 1 second the plane climbs 25 feet.

Also bear in mind that the aircraft is still accelarating while all this is going on.



Before the flight various performance are calculated

V1 = after a jet passes this speed no matter what happens the crew will continue the take off. After V1 there is enough performance to fly, even with an engine failure. Trying to stop at that point is more dangerous than taking off and dealing with it in the air.

Vr (useually faster than V1) = the speed where the pilot will pull the nose up to the take off pitch.

Acclerate/Stop distance = the distance required to accelrate to V1 and then perform an emrgency stop. For passenger flights this must be shorter than the available runway.


Dont worry about being a newbie, everybody here enjoys helping the newbies out. That's what this site is here for.
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Big wing = citation performance = crustacean speeds = despair

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Point of Order Sir, when you say citation performance = crustacean speeds you mean to say 500 series citation performance. My 500 series citation (straight wing ) was a 370 kt TAS airplane but my 650 citation ( swept wing ) is a 460 + kt TAS airplane, saw 480 kt TAS last week.

I'm really not insulted nor feel the need to defend my citation, I'm just needing a post fix.

Jim
 
Yup, I meant the 500 series!

I'd need JATO assist to catch anything later! The X is darned near trans-sonic!
 
The DC-10/MD-10/MD-11 is no different than any other big airplane (widebody in particular). Typical initial climb body angle is about 15 degrees, higher if light. Rotation rate for anything I've flown, from the 727 on up, is nominally 2.5 degrees/second. So, that means that it takes 6 seconds to rotate. Faster rotation can mean getting the tail before liftoff on any of them, slower and you are not making the optimum performance (not really a big deal at most airports with all engines running, however).

Plenty of anti- Douglas bias out there, so not hard to find misinformation on that.
 
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Big wing = citation performance = crustacean speeds = despair

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Point of Order Sir, when you say citation performance = crustacean speeds you mean to say 500 series citation performance. My 500 series citation (straight wing ) was a 370 kt TAS airplane but my 650 citation ( swept wing ) is a 460 + kt TAS airplane, saw 480 kt TAS last week.

I'm really not insulted nor feel the need to defend my citation, I'm just needing a post fix.

Jim

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He was probably referring to the Hog.
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Probably about the same on the -88. Slow rotation until the aircraft unsticks and starts climbing, then on up to 20 degrees nose up until acceleration altitude.
 
Nothing like seeing a heavy on a hot day in ATL use 27R/9L and take up almost all of the runway...
 
We don't have a heck of a lot of wing!
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In the MD-90, we're flying 260 KIAS below 10,000 fairly often.
 
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