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Aircraft Vs Thread 5


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Latest A400M pic.

Props 1 and 3 rotate opposite of 2 and 4. I'm unaware of counter-rotating implemented that way--normally aren't all engines on the same wing going the same direction? I'm thinking there could be some really weird P-effect going on if one outboard engine quits...

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Latest A400M pic.

Props 1 and 3 rotate opposite of 2 and 4. I'm unaware of counter-rotating implemented that way--normally aren't all engines on the same wing going the same direction? I'm thinking there could be some really weird P-effect going on if one outboard engine quits...

Perhaps is a form of thrust reversing on turboprops? IE, the pilot landed, and didn't bother to rotate the props back to the "normal" orientation?

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No, that's how they're designed. They even have 2 different engines designed, for the 2 different gearboxes needed to accomodate the 2 different props. Logistics nightmare... (and no prop blade rotates THAT much for reversing)

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No, that's how they're designed. They even have 2 different engines designed, for the 2 different gearboxes needed to accomodate the 2 different props. Logistics nightmare... (and no prop blade rotates THAT much for reversing)

According to Airbus they only have one engine and two gearbox types. They consider this an acceptable trade off considering the advantages they anticipate;

Perhaps one of the most interesting A400M innovations was the decision to adopt “handed” propellers whereby the propellers of each pair of engines turn towards each other.

This counter-rotation characteristic is known as Down-Between-Engines (DBE) and the A400M will be the first aircraft ever to use such a configuration. The advantages of DBE have far-reaching effects both aerodynamically and structurally. Firstly, airflow over the wings is symmetrical, improving lift characteristics and the lateral stability of the aircraft. Secondly, DBE allows for an optimum wing design by eliminating most of the effects of torque and prop-wash on each wing, concentrating the airflow over the most efficient portion of the wing located between the engines. DBE also reduces the “critical engine” effect of severe yaw in the event of an outboard engine failure. The result allows a 17% reduction in the area of the vertical tail surface.

Further aerodynamic advantages inherent in DBE have been found to give a 4% increase in lift from the wing at slow speed, which enables, for the same total lift, a simpler, lighter flap system to be employed. As a consequence of the lessening of the aerodynamic forces applied to the flaps, the surface area of the horizontal tail-plane can also be reduced by 8%.

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AFAIK the gearbox change is enough that it effectively creates 2 engine types--it's not easy to swap them around. DC-10 was like that. I think the engines were "left" and "center/right" on it. You CAN change them, but they really don't want to. And there's still 2 props---props which the plane itself can't carry inside.

It's generally considered a really good idea for military cargo planes to be able to transport their own engines and props.

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Hard to find specs for those, but this is one of the larger ones (won't do a 747, but most anything else): http://www.caranddriver.com/reviews/car/00...le/specs_page_2

Bigger one, fewer specs, but an interesting note: http://www.douglas-equipment.com/uploads/p...d765c9a18a5.pdf

112,000lbs of tractive effort exceeds that of most any steam locomotive. Though it has the huge advantage of using rubber tires on pavement, instead of slick steel tires on steel rails.

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Any thoughts on my questions regarding the swing-wing NATF, David?

Or anyone else for that matter :)

I can cover that one, or at least half of it. I have not seen any information on how the NATF would overcome the RCS concerns of a swing wing, there's very little detailed info on Lockheed's NATF proposal (and if you think that's bad just try finding info on the F-23N). It's even possible the info you want is classified.

As for why a swing wing was used in the first place, your surmise is pretty much correct. The only way to meet the Navy's landing speed, weight, and top speed requirements was to use a swing wing. The standard F-22 wing is fine for the speeds the Air Force lands at, but to get it on a carrier you need to go much slower which either requires adding various high lift devices (big flaps etc) or a swing wing. When you add those high lift devices to a folding mechanism for a fixed wing and you end up with a pretty heavy plane that likely would have too much drag to reach the speeds the Navy wanted.

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Hard to find specs for those, but this is one of the larger ones (won't do a 747, but most anything else): http://www.caranddriver.com/reviews/car/00...le/specs_page_2

Bigger one, fewer specs, but an interesting note: http://www.douglas-equipment.com/uploads/p...d765c9a18a5.pdf

112,000lbs of tractive effort exceeds that of most any steam locomotive. Though it has the huge advantage of using rubber tires on pavement, instead of slick steel tires on steel rails.

Cool. Thanks David. 70 tons. I understand that most of that is lead?

Got interested because I just found out that the M577 from Aliens was built over one.

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Last airshow I'm going to this year, and likely the last San Francisco Fleet Week I'll make it to for a while as my wife and I are moving back to Boston at the end of the month. I am glad I could get a good picture of the sneak pass over the bay, who's jelous of the GIB (guy in back) getting the incentive ride?

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Had some others admiring the show as well (one of the other great little touches about Fleet Week in San Francisco):

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Edited by Nied
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