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There are freighters, and then there are military freighters. Civil freighters are designed around standard containers that don't require loading off the ends of the airplane. The special cases are moving vehicles and manufacturing equipment, hence civil use of AN-124's and AN-224's, Guppies, or 'Lifters. End loading is really not suitable for the tempo or space available during passenger operations, especially when the airplane has to be supported on jacks or a special loading fixture/floor is required, along with all the special equipment required to support the operation. View Quote View All Quotes View All Quotes Quoted:
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You need to check the take off weights again. People weigh less than tanks. Doesn't explain the 747 freighter. That's a conversion. There are freighters, and then there are military freighters. Civil freighters are designed around standard containers that don't require loading off the ends of the airplane. The special cases are moving vehicles and manufacturing equipment, hence civil use of AN-124's and AN-224's, Guppies, or 'Lifters. End loading is really not suitable for the tempo or space available during passenger operations, especially when the airplane has to be supported on jacks or a special loading fixture/floor is required, along with all the special equipment required to support the operation. 747 was designed as a freighter wasn't it? thats why the cockpit was up high so they could put the nose hatch in. |
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Quoted: Additionally, roll on, roll off capability. There are few cargo handling facilities at unimproved strips, so the cargo is closer to the ground. View Quote |
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I'm also wondering which is the more efficient design, and I would think commercial keeping the aircraft more streamline. We need some wind-tunnel and treadmill results View Quote View All Quotes View All Quotes Quoted:
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And I would assume to keep the jet engines below the passengers, for both noise reduction and for a view out of the passenger cabin? Just a W.A.G I'm also wondering which is the more efficient design, and I would think commercial keeping the aircraft more streamline. We need some wind-tunnel and treadmill results fify |
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I really like the high wing design, simply because Im not a fan of impacting on parts of the aircraft aft of the paratroop door......
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747 was designed as a freighter wasn't it? thats why the cockpit was up high so they could put the nose hatch in. View Quote Not necessarily designed as, but certainly designed with that in mind. http://www.airspacemag.com/how-things-work/sweetman.html |
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Dirt.
Mil aircraft have to be able to land gear up and take off again. Look up pics, they used to test them at Sicily DZ, pretty cool shit. And Mil don't care if the cargo aka passengers are sitting right next to a loud engine. Also requires less caution when operating GSE and other equipment vehicles in close proximity. |
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What about anhedral versus dihedral? A C-17 or C-5 looks like it has anhedral, while all the commercial planes have significant amounts of dihedral. It seems like it would be difficult to have anhedral on a low wing. Are the military transports designed for less lateral stability, or is there something else at play?
ETA I guess having a high wing let's you get away with less dihedral, but there seems to be a pretty big difference... maybe more than enough to be explained by that.
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On the other hand, how much quieter are commercial aircraft with the jets below the passenger level?
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A driving requirement for military cargo aircraft is to have the cargo floor height close to cargo floor height on trucks, so cargo can be rolled out the back of the cargo plane onto trucks to carry that cargo out to the field. A high wing configuration aircraft provides the easiest way for aircraft manufacturers to meet that requirement. Otherwise, very complex and heavy kneeling landing gear systems would be needed to get a low-wing aircraft's cargo floor down to that required height.
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Dirt. Mil aircraft have to be able to land gear up and take off again. Look up pics, they used to test them at Sicily DZ, pretty cool shit. And Mil don't care if the cargo aka passengers are sitting right next to a loud engine. Also requires less caution when operating GSE and other equipment vehicles in close proximity. View Quote Ummm. What? |
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Not a "cargo" 747 - But it shows why a high wing spar is better for military purposes: http://up-ship.com/blog/wp-content/uploads/2011/08/747-200F-ALCM-Carrier-1024x288.jpg http://up-ship.com/blog/wp-content/uploads/2011/08/us004208949-003.gif View Quote Holy shit that's a lot of cruise missiles. |
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747 was designed as a freighter wasn't it? thats why the cockpit was up high so they could put the nose hatch in. View Quote View All Quotes View All Quotes Quoted:
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You need to check the take off weights again. People weigh less than tanks. Doesn't explain the 747 freighter. That's a conversion. There are freighters, and then there are military freighters. Civil freighters are designed around standard containers that don't require loading off the ends of the airplane. The special cases are moving vehicles and manufacturing equipment, hence civil use of AN-124's and AN-224's, Guppies, or 'Lifters. End loading is really not suitable for the tempo or space available during passenger operations, especially when the airplane has to be supported on jacks or a special loading fixture/floor is required, along with all the special equipment required to support the operation. 747 was designed as a freighter wasn't it? thats why the cockpit was up high so they could put the nose hatch in. Nope, the original design was to incorporate an all passenger, all freight or combi freight plus passenger missions. All three were considered from the start, not just one. Boeing was putting the company at risk and so they went all in. The 747-8 was designed to intrude into the A-380 cargo mission with an airplane that can carry lots of weight in a compact efficient package. The A-380 can carry lots of feathers. I've watched a couple of AN-124 airplanes with loads that were just plain amazing. One was the guts of a bottling plant from Italy. Part was unloaded out the rear ramp, part was unloaded out the front. The airplane had to be stabilized so it couldn't squat on the ramp, and the front required erection of a bridge crane that to move the load onto a custom and extremely long trailer that looked like a bridge on wheels that was carefully lined up in front of the nose. |
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What about anhedral versus dihedral? A C-17 or C-5 looks like it has anhedral, while all the commercial planes have significant amounts of dihedral. It seems like it would be difficult to have anhedral on a low wing. Are the military transports designed for less lateral stability, or is there something else at play? ETA I guess having a high wing let's you get away with less dihedral, but there seems to be a pretty big difference... maybe more than enough to be explained by that. View Quote The anhedral/dihedral decision is strongly based on the wing sweep, not on the "logical" pendulum effect of a high wing. Modern stability aids allow overcoming weak lateral directional stability, so one configuration might rely on less dihedral or anhedral for some other reason, knowing it can be made up electronically. |
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Dirt. Mil aircraft have to be able to land gear up and take off again. Look up pics, they used to test them at Sicily DZ, pretty cool shit. And Mil don't care if the cargo aka passengers are sitting right next to a loud engine. Also requires less caution when operating GSE and other equipment vehicles in close proximity. Ummm. What? Say again? |
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No. Ground effect would be stronger with a lower wing. View Quote View All Quotes View All Quotes Quoted:
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2. Short take-off. With the flaps down and at take-off thrust the wing/ground effect can get you airborne witrh less distance. m No. Ground effect would be stronger with a lower wing. That's what I thought, but wasn't sure enough to say it. |
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The anhedral/dihedral decision is strongly based on the wing sweep, not on the "logical" pendulum effect of a high wing. Modern stability aids allow overcoming weak lateral directional stability, so one configuration might rely on less dihedral or anhedral for some other reason, knowing it can be made up electronically. View Quote View All Quotes View All Quotes Quoted:
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What about anhedral versus dihedral? A C-17 or C-5 looks like it has anhedral, while all the commercial planes have significant amounts of dihedral. It seems like it would be difficult to have anhedral on a low wing. Are the military transports designed for less lateral stability, or is there something else at play? ETA I guess having a high wing let's you get away with less dihedral, but there seems to be a pretty big difference... maybe more than enough to be explained by that. The anhedral/dihedral decision is strongly based on the wing sweep, not on the "logical" pendulum effect of a high wing. Modern stability aids allow overcoming weak lateral directional stability, so one configuration might rely on less dihedral or anhedral for some other reason, knowing it can be made up electronically. I was under the impression that high wing was inherently more stable, hence the anhedral to balance high wing stability with the anhedral's increased maneuverability. |
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Dirt. Mil aircraft have to be able to land gear up and take off again. Look up pics, they used to test them at Sicily DZ, pretty cool shit. And Mil don't care if the cargo aka passengers are sitting right next to a loud engine. Also requires less caution when operating GSE and other equipment vehicles in close proximity. Ummm. What? Say again? Again. |
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FOD
Clearance for engines on unimproved runways. Visibility (wings block a lot of sky) Body closer to the tarmac for easier loading/unloading |
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Dirt. Mil aircraft have to be able to land gear up and take off again. Look up pics, they used to test them at Sicily DZ, pretty cool shit. And Mil don't care if the cargo aka passengers are sitting right next to a loud engine. Also requires less caution when operating GSE and other equipment vehicles in close proximity. View Quote This? http://www.youtube.com/watch?v=XKeCVYTiIWg Not really "landing" is it? |
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Engines need to be higher so you don't suck a goat with an afghan attached to its ass through it. View Quote Or a container: http://www.liveleak.com/view?i=d20_1387706399 |
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Quoted: No. Ground effect would be stronger with a lower wing. View Quote View All Quotes View All Quotes Quoted: Quoted: 2. Short take-off. With the flaps down and at take-off thrust the wing/ground effect can get you airborne witrh less distance. m No. Ground effect would be stronger with a lower wing. And all that FOD is just going to stay on the ground? Wing in ground effect is mostly effect up to approximately one wingspan above ground level. That extra few feet isn't going to matter. That few feet will help keep crap from getting ingested into the engine. I'm not talking about low level flight here, just getting the weight off of the wheels earlier, accelerating faster, and clearing obstacles in a shorter distance. m |
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And all that FOD is just going to stay on the ground? Wing in ground effect is mostly effect up to approximately one wingspan above ground level. That extra few feet isn't going to matter. That few feet will help keep crap from getting ingested. I'm not talking about low level flight here, just getting the weight off of the wheels earlier, accelerating faster, and clearing obstacles in a shorter distance. m View Quote View All Quotes View All Quotes Quoted:
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2. Short take-off. With the flaps down and at take-off thrust the wing/ground effect can get you airborne witrh less distance. m No. Ground effect would be stronger with a lower wing. And all that FOD is just going to stay on the ground? Wing in ground effect is mostly effect up to approximately one wingspan above ground level. That extra few feet isn't going to matter. That few feet will help keep crap from getting ingested. I'm not talking about low level flight here, just getting the weight off of the wheels earlier, accelerating faster, and clearing obstacles in a shorter distance. m you still haven't explained how a high wing gets you airborne with less distance. Intuitively, the closer to the ground, the more pronounced the ground effect. we aren't talking about FOD. We are talking about take off distance. |
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You need to check the take off weights again. People weigh less than tanks. Doesn't explain the 747 freighter. Which lost in direct competition to the C-5. The main reasons being: 1. Loading and unloading it is a massive pain in the ass. 2. No rear cargo ramp/door, I can't think of any low wing airplane that has one. 3. The C-5 squats and kneels, makes loading and unloading rolling stock a piece of cake. |
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Which lost in direct competition to the C-5. The main reasons being: 1. Loading and unloading it is a massive pain in the ass. 2. No rear cargo ramp/door, I can't think of any low wing airplane that has one. 3. The C-5 squats and kneels, makes loading and unloading rolling stock a piece of cake. View Quote View All Quotes View All Quotes Quoted:
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You need to check the take off weights again. People weigh less than tanks. Doesn't explain the 747 freighter. Which lost in direct competition to the C-5. The main reasons being: 1. Loading and unloading it is a massive pain in the ass. 2. No rear cargo ramp/door, I can't think of any low wing airplane that has one. 3. The C-5 squats and kneels, makes loading and unloading rolling stock a piece of cake. Ironic that the criteria for that was: 1. Ease of Loading 2. Actually flies And in that order. |
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Ironic that the criteria for that was: 1. Ease of Loading 2. Actually flies And in that order. View Quote View All Quotes View All Quotes Quoted:
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You need to check the take off weights again. People weigh less than tanks. Doesn't explain the 747 freighter. Which lost in direct competition to the C-5. The main reasons being: 1. Loading and unloading it is a massive pain in the ass. 2. No rear cargo ramp/door, I can't think of any low wing airplane that has one. 3. The C-5 squats and kneels, makes loading and unloading rolling stock a piece of cake. Ironic that the criteria for that was: 1. Ease of Loading 2. Actually flies And in that order. Lockheed's been lying to the bill payer for a loooooooong time about reliability. |
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And all that FOD is just going to stay on the ground? Wing in ground effect is mostly effect up to approximately one wingspan above ground level. That extra few feet isn't going to matter. That few feet will help keep crap from getting ingested into the engine. I'm not talking about low level flight here, just getting the weight off of the wheels earlier, accelerating faster, and clearing obstacles in a shorter distance. m View Quote View All Quotes View All Quotes Quoted:
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2. Short take-off. With the flaps down and at take-off thrust the wing/ground effect can get you airborne witrh less distance. m No. Ground effect would be stronger with a lower wing. And all that FOD is just going to stay on the ground? Wing in ground effect is mostly effect up to approximately one wingspan above ground level. That extra few feet isn't going to matter. That few feet will help keep crap from getting ingested into the engine. I'm not talking about low level flight here, just getting the weight off of the wheels earlier, accelerating faster, and clearing obstacles in a shorter distance. m FOD avoidance was a good reason for a high wing as is ease of load/unload. Increased ground effect is not a reason for a high wing. It reduces ground effect. In fact, low wing is probably safer for in ground effect flight since for a given wing/engine height above the deck, the belly of the aircraft would be farther from the ground. Ground effect does occur up to one wingspan AGL, but its effects diminish the higher the wing above ground. |
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I was under the impression that high wing was inherently more stable, hence the anhedral to balance high wing stability with the anhedral's increased maneuverability. View Quote View All Quotes View All Quotes Quoted:
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What about anhedral versus dihedral? A C-17 or C-5 looks like it has anhedral, while all the commercial planes have significant amounts of dihedral. It seems like it would be difficult to have anhedral on a low wing. Are the military transports designed for less lateral stability, or is there something else at play? ETA I guess having a high wing let's you get away with less dihedral, but there seems to be a pretty big difference... maybe more than enough to be explained by that. The anhedral/dihedral decision is strongly based on the wing sweep, not on the "logical" pendulum effect of a high wing. Modern stability aids allow overcoming weak lateral directional stability, so one configuration might rely on less dihedral or anhedral for some other reason, knowing it can be made up electronically. I was under the impression that high wing was inherently more stable, hence the anhedral to balance high wing stability with the anhedral's increased maneuverability. Sweep increases lateral directional stability, so sometimes anhedral is used to reduce the effect. The high location is a contributor but not as strong as sweep. Anhedral in low wings may cause the engines to drag. These airplanes are not rigid, so deflection is taken into account, too. |
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you still haven't explained how a high wing gets you airborne with less distance. Intuitively, the closer to the ground, the more pronounced the ground effect. we aren't talking about FOD. We are talking about take off distance. View Quote View All Quotes View All Quotes Quoted:
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2. Short take-off. With the flaps down and at take-off thrust the wing/ground effect can get you airborne witrh less distance. m No. Ground effect would be stronger with a lower wing. And all that FOD is just going to stay on the ground? Wing in ground effect is mostly effect up to approximately one wingspan above ground level. That extra few feet isn't going to matter. That few feet will help keep crap from getting ingested. I'm not talking about low level flight here, just getting the weight off of the wheels earlier, accelerating faster, and clearing obstacles in a shorter distance. m you still haven't explained how a high wing gets you airborne with less distance. Intuitively, the closer to the ground, the more pronounced the ground effect. we aren't talking about FOD. We are talking about take off distance. High wing airplanes with no flaps or simple flaps might generate a slightly higher maximum lift coefficient to aid takeoff, but on a sophisticated airplane it's going to buried. Ground effect helps if the pilot can break contact with the ground quickly then allow the airplane to accelerate in ground effect to climb speed; the airborne drag is less than running on the ground, so the airplane accelerates better and overall takeoff distance to climb over an obstacle is less. Differentiating between high wing and low wing would be about impossible except on paper. A low wing airplane is more likely to have a tricycle landing gear, so the incidence of the wing is more favorable from the start of the ground roll. Tail dragger airplanes tend to be operated by getting the tailwheel off the ground as quickly as possible, and the sharp pilot looking for best takeoff performance will depress the tail slightly during the run to take off quickly (although he might opt to bring it up to a level attitude for a couple seconds to accelerate, then depress the tailwheel without letting the wheel touch). Nose wheel airplanes will be operated in a similar manner by getting the nose wheel off the ground quickly for soft field operations; short fields call for keeping the airplane level to accelerate, but often gets blended with soft field methods. It's hard to keep a nose wheel just an inch off the ground with a low incidence due to strut extension. |
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Lockheed's been lying to the bill payer for a loooooooong time about reliability. View Quote My friends that fly C-5s have almost nothing good to say about that plane, ESPECIALLY in the reliability dept. But it's plausible deniability when the plane "breaks down" in Germany, and you can spend a few days at the biergarten while they fix it. |
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My friends that fly C-5s have almost nothing good to say about that plane, ESPECIALLY in the reliability dept. But it's plausible deniability when the plane "breaks down" in Germany, and you can spend a few days at the biergarten while they fix it. View Quote View All Quotes View All Quotes Quoted:
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Lockheed's been lying to the bill payer for a loooooooong time about reliability. My friends that fly C-5s have almost nothing good to say about that plane, ESPECIALLY in the reliability dept. But it's plausible deniability when the plane "breaks down" in Germany, and you can spend a few days at the biergarten while they fix it. serial lying about maintenance while collecting TDY and avoiding missions is a matter of pride in airlift units it appears. |
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Prop driven aircraft with wing mounted engines need a high wing mount for obvious reasons. Look at how tall the landing gear is on the Connie. http://cdn-www.airliners.net/aviation-photos/photos/8/2/1/0095128.jpg View Quote View All Quotes View All Quotes Quoted:
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I will have to ask my BIL this question since he works on the C130 line and see if he can get an answer about this. Prop driven aircraft with wing mounted engines need a high wing mount for obvious reasons. Look at how tall the landing gear is on the Connie. http://cdn-www.airliners.net/aviation-photos/photos/8/2/1/0095128.jpg The dodge for that is to put the thrust line above the leading edge of the wing. Looks like ass with a radial engine, too. |
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I'm sure this is part of it, the spar carry though for the wing is not a inconsequential part. I'm not sure about the C17 but the C5 can actually "squat" to get lower to the ground when you are loading it break while you're calling for the MRT to come fix it. View Quote View All Quotes View All Quotes Quoted:
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Additionally, roll on, roll off capability. There are few cargo handling facilities at unimproved strips, so the cargo is closer to the ground. FIFY. |
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My friends that fly C-5s have almost nothing good to say about that plane, ESPECIALLY in the reliability dept. But it's plausible deniability when the plane "breaks down" in Germany, and you can spend a few days at the biergarten while they fix it. View Quote View All Quotes View All Quotes Quoted:
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Lockheed's been lying to the bill payer for a loooooooong time about reliability. My friends that fly C-5s have almost nothing good to say about that plane, ESPECIALLY in the reliability dept. But it's plausible deniability when the plane "breaks down" in Germany, and you can spend a few days at the biergarten while they fix it. I have a lot of good things to say about it...where are your friends stationed? |
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serial lying about maintenance while collecting TDY and avoiding missions is a matter of pride in airlift units it appears. View Quote View All Quotes View All Quotes Quoted:
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Lockheed's been lying to the bill payer for a loooooooong time about reliability. My friends that fly C-5s have almost nothing good to say about that plane, ESPECIALLY in the reliability dept. But it's plausible deniability when the plane "breaks down" in Germany, and you can spend a few days at the biergarten while they fix it. serial lying about maintenance while collecting TDY and avoiding missions is a matter of pride in airlift units it appears. If you think something is wrong with the plane, Germany is a good place to get it checked out. |
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