Legacy of B-2 Bomber Innovations Apparent in J-UCAS and Other Programs  
By William B. Scott  



STEALTHY GENESIS

Aviation Week & Space Technology periodically takes an over-the-shoulder look to capture lessons from past aerospace programs, but aided by the perspective of time and in-service experience. Such revisits can benefit current and future system developments, perhaps avoiding the costly and painful trials of rediscovery and relearning. The articles that follow focus on the B-2's development and how the design techniques, technologies and management approaches it fostered are being applied today.

Although the contract for what became the U.S. Air Force's B-2 bomber was awarded almost 25 years ago, much about the stealthy "Spirit" and how it evolved from idea to reality remains classified or consigned to the memory of a few. Consequently, the B-2's profound impact on air warfare and the global aerospace industry has yet to be fully recognized and appreciated.

An impressive list of technologies, design tools, management techniques, manufacturing processes and myriad lessons spawned by the B-2 program are contributing to many commercial and military programs. For example, Northrop Grumman's Unmanned Combat Aircraft System (UCAS) X-47, the F/A-18E/F Super Hornet and even Boeing's 777 airliner have close ties to the B-2.

By almost any measure, the bomber's development was one of the largest, most technically complex, expensive and demanding programs in aerospace history. But the final product dramatically changed air combat forever. The B-2's "stealth" or low observability (LO) enables unprecedented penetration of enemy territory, essentially neutralizing very costly air defense systems. Precision weapon delivery in all weather conditions, day or night, changed an air warfare tenet from "sorties per target" to "numbers of targets per sortie." In the B-2's case, a single bomber carrying 16 conventional weapons can destroy 16 targets. The same mission once would have required dozens of aircraft dropping hundreds of bombs.

Designed as a Cold War weapon system, the B-2 was also a central player in an economic war to break the then-Soviet Union's financial back. The U.S. chose an aggressive offensive strategy, because history had proven it is much costlier to build strong defenses than to field effective offenses. LO aircraft such as the F-117 Nighthawk and B-2 Spirit would have forced the Soviets to spend enormous sums on air defense systems.

When the B-2 program started, "we were quite cognizant that [its] purpose was more than just the next weapon system," recalls Albert F. Myers, Northrop Grumman's corporate vice president for strategy and technology. "In the early days, [Defense Dept. leaders] characterized the program as being as important as the Manhattan Project," the massive World War II effort to develop nuclear weapons.

Myers joined Northrop Corp. in 1981 as manager of B-2 flight controls engineering, and later served as chief project engineer, then deputy program manager and vice president of test operations. He plans to retire this summer.

During the Cold War, weapon system performance was given top priority, trumping cost considerations. Whatever resources were deemed necessary to meet national security goals, they were made available, despite the cost.

"We kept a top-10 list of [B-2 concerns] on the briefing-room wall," Myers recalls. "We were seven years into the program before 'cost' made that list." But those days are gone. "I'm not sure we'll ever see another program like that again," he adds.

In the late 1970s, the Carter administration committed to developing what originally was known as the Advanced Strategic Penetrating Aircraft (ASPA). The ASPA was intended to be stealthy, have a large range-payload capability and deliver both nuclear and conventional weapons.

Some press reports have claimed that the end of the Cold War forced Northrop to redesign a nuclear-only B-2 for a conventional role. Not so, Myers says. "The conventional capability was a hard design requirement from the very onset of the program."

In 1979, the first sketch of Northrop's ASPA concept was drawn (see graphic). "From then until contract award [in 1981], the basic arrangement changed very little," Myers notes. A flying-wing design was dictated by the requirement to fly at high altitudes and carry a large payload over long distances. But, for the first time in aerospace history, such a large-volume aircraft simultaneously would be "low-observable"--have very small radar, infrared and other signatures--and be aerodynamically efficient. Northrop's blended-body offering was chosen over Lockheed's, a design that remains classified.

Northrop immediately faced a daunting technical challenge: design and build a long-range, LO bomber having considerable internal space for fuel and weapons. Those considerations dictated a flying-wing configuration, company engineers decided. Many believe Northrop's history with the XB-35 and YB-49 flying wings strongly influenced the B-2's design, but any connection was tenuous, at best. Instead, the B-2 traces its lineage to a number of research-and-development and concept demonstration programs in the 1970s--particularly Tacit Blue, a bathtub-shape proof-of-concept aircraft.

"From my point of view, the B-2 was a direct technical follow-on to Tacit Blue," Myers says. "[It] was the first aircraft designed . . . with the Northrop approach to adding volume to a smooth-surface planform. [It provided] real-world, inflight validation of our design assumptions and approach." Company engineers also learned a lot about engine-inlet geometries for stealthy aircraft.

Original Air Force requirements called for a bomber that would fly at high altitudes and high speeds, then drop to low altitudes and high airspeeds (actual numbers are still classified). But USAF officials changed their minds prior to contract award and "said they wanted the right-hand side of the [flight] envelope to stay at the same Mach number all the way down [to low altitude]," Myers recalls. "So, here we had an aircraft designed as a high-altitude glider--optimized to meet that high-altitude requirement--and now we were confronted with the need to fly at very high dynamic pressures. That was obviously a different game." Two years into the program, engineers concluded those new requirements would force a complete wing redesign (see p. 59).

Northrop launched its design effort by identifying, then managing the program through a set of risk-reduction and -closure tasks. "Managing those risk-closure plans was a major element of the overall program-management [philosophy]," Myers says. The same approach is being used on the company's UCAS effort. For the B-2, those plans included:

*Developing an active flight control system to ensure stability. "At best, the vehicle was neutrally stable in all three axes," he notes.

*Shaping the exterior to minimize the B-2's radar signature, a challenge that ultimately affected most aircraft systems and features.

*Designing and building all-composite skins and structures--the first aircraft to use composites so extensively. This challenge was considered so risky that, for a while, a second team was set up to design an aluminum wing in parallel. A metal structure would have been much heavier, greatly reducing the B-2's range-payload capability. Thus, a considerable effort was devoted to developing a composite version, and it paid off; the aluminum-wing option was dropped before the first Preliminary Design Review took place. "Today, [developing a composite wing] seems straightforward, because the world's used to composite vehicles. But it was a big deal then," Myers notes.

The bomber would have to be designed as an integral system, then manufactured to extremely tight tolerances, to meet LO requirements. Consequently, the B-2 became the first aircraft designed completely via computers, ensuring design and fabrication phases were tightly coordinated, Myers says. However, the analytical models and computer-aided-design/manufacturing (CAD/CAM) tools to accomplish this weren't available in the early 1980s.

In particular, the active flight control system dictated that the entire aircraft be modeled precisely. "I could easily count on one hand the number of people in the [U.S.] who had tried to go through the analytical process for an [active] flight control system," says Myers, who headed that critical risk-closure area at the time. "The tools to develop a [digital] model for a fully coupled, aerostructural, servoelastic system didn't exist. People had done single-point, simplified models, but we needed one that encompassed the full structural dynamics; the full steady and unsteady aerodynamics, all in one fully coupled model."

Having previously worked on NASA's F8 Crusader fly-by-wire research program, Myers knew the handful of people capable of developing such a model, and set out to gain their services through subcontracts. Although these experts belonged to NASA, Honeywell and other organizations, managers were never told what their own employees were doing for Northrop.

"Nobody in their chain of command was ever briefed [about the B-2]. And they were told they couldn't ask," Myers adds with a smile, underscoring how secret the program was at the time. "The guys just disappeared for about nine months. That team pulled together the analytical capabilities, [drawing on] unsteady aerodynamic models, Nastran models, static-aerodynamic models and the wind tunnel database. From that, we [created] a fully coupled aerostructural, servoelastic model" that enabled redesigning the entire bomber.

"Nothing in this aircraft doesn't have at least three or four major systems tightly interacting. It's like solving big simultaneous equations. There isn't any way to do it serially," he explains.

"Zone management" was another Northrop innovation. The entire aircraft was divided into zones--structures, flight controls, propulsion, fuel and the environmental control system, for example--each managed by a single design engineer. "He was responsible for everything that went into that part of the aircraft--all installations, all the wiring, piping, where structure-penetrations were located--everything," Myers recalls. "It was a real successful approach on the B-2, and the same zone-management [strategy] is being used on UCAS. It's a total-systems approach."

Because the B-2 is such a highly integrated vehicle, zone managers worked closely with suppliers, even training many of them. Challenges included:

*Designing and installing 28 antennas, but with the low-observability constraint that none could present a radio-frequency signature. Suppliers would "give us a blank stare, as if to say, 'Isn't that an oxymoron?' Because there was no alternative, we had to develop an in-house [Northrop] group of engineers and physicists to figure out how to design antennas that worked in an LO system," Myers says. "We had no intention of getting into the antenna business, so we taught manufacturers how to design and build [LO] antennas."

*Developing a flight control system (FCS) that was compatible with low-observability. Although details are still classified, it's known that exterior surface movements are automatically limited when operating in "stealth mode."

*Active center-of-gravity control, which dictated that the FCS be integrated with the fuel system to maintain stability as fuel burned.

*Ensuring the FCS compensated for pitch changes as engine-thrust varied and when weapons bays were opened and closed.

*Developing flush-mounted air data ports that met LO requirements. "They all measure a blend of static and dynamic [air] pressure," Myers says. "With that data, the [B-2] computes angle-of-attack (AOA), angle-of-sideslip, altitude, airspeed and Mach number. And it uses AOA in the primary feedback loop for gust-load alleviation. That hadn't been done before."

Many of these B-2 "lessons-learned" are being applied to Northrop Grumman's UCAS design. For instance, both the B-2 and X-47 have their nose and main landing gear relatively close together, which puts considerable weight on the nose gear. That requires "active feedback into the nose-wheel-steering control" for good ground handling. "That was a unique challenge," Myers recalls. "But [UCAS engineers] didn't have to relearn it. We knew it was going to be a problem, so we adopted the same design approach" developed for the B-2.

Similarly, UCAS designers are using the B-2-developed flush-mounted air data system and integrated flight controls approach. However, unlike the B-2, the X-47's "flight control system controls the engine," says T. Scott Winship, the company's UCAS program director. "Throttle position is used to compensate for thrust effects."

While its impact on both manned and unmanned air vehicle development is evident, the B-2 program has had far-reaching, yet subtle influences on today's Northrop Grumman. "I would argue that the B-2 was the first weapon system totally designed as a weapon system. It wasn't designed as an airplane, then converted to a weapon system.

"That design [process] . . . helped formulate what we thought would become important in the future: integral systems. The experience [gained] by thinking through the B-2's total-weapon-system concept helped us form that vision. Without the [B-2 experience], I don't think we'd have been able to see it as clearly. The design of a [highly integrated] airplane and the design of a company have more in common than I would have expected."

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Tag

That is spectacular.    I would kill for those kinds of engineers!!!


 The only thing our engineers ( at my company ) can do is ask mommy to tie their shoelaces.   Save one, and that one is a woman....and she is so mind numbingly brilliant it's amazing....and more competant than any man that has ever worked at my company.

Quoted: *Active center-of-gravity control, which dictated that the FCS be integrated with the fuel system to maintain stability as fuel burned.

That will prevent capucinno spills during the mission.

Quoted: Save one, and that one is a woman....and she is so mind numbingly brilliant it's amazing....and more competant than any man that has ever worked at my company.

Can she cook and is she hot? Inquiring heads want to know.

If they tried to build it today all you would hear are the so called "experts" screaming about wasting money on all this new and unproven technology...just like they are doing on the national missile defense shield.  "Why are we spending billions of dollars on that project when they can't even prove the technology works." is what we are hearing right now and we can actually see the test results.  Can you imagine how loud those people would have been screaming if they knew we were developing an "invisible" plane?

Another tag for when I have more time.


-K

Quoted: Quoted: *Active center-of-gravity control, which dictated that the FCS be integrated with the fuel system to maintain stability as fuel burned. That will prevent capucinno spills during the mission.

You have something against the Air Force?

Quoted: Quoted: Quoted: *Active center-of-gravity control, which dictated that the FCS be integrated with the fuel system to maintain stability as fuel burned. That will prevent capucinno spills during the mission. You have something against the Air Force?

Obviously.  It would do a lot more than "spill a cappuccino" if you had a sudden departure from controlled flight brought on by poor CG management by the Flight Control System.  Yeah, those B-2 pilots are real Gucci Prima Donnas, huh?  40+ hour long flights in a cramped ass cockpit with no crapper, hot food (maybe an MRE or two), or room to stretch out.  Pansies, real men would'nt fly 20,000 mile combat missions.  

Quoted: Quoted: Quoted: Quoted: *Active center-of-gravity control, which dictated that the FCS be integrated with the fuel system to maintain stability as fuel burned. That will prevent capucinno spills during the mission. You have something against the Air Force? Obviously.  It would do a lot more than "spill a cappuccino" if you had a sudden departure from controlled flight brought on by poor CG management by the Flight Control System.  Yeah, those B-2 pilots are real Gucci Prima Donnas, huh?  40+ hour long flights in a cramped ass cockpit with no crapper, hot food (maybe an MRE or two), or room to stretch out.  Pansies, real men would'nt fly 20,000 mile combat missions.

I just watched a show on the B2 crews recently.

They do have toilets on the plane, and they do have a cot on the plane that the pilots take turns taking naps in.

I'm not saying they have it soft at all. They fly the most sophisticated airplane ever made across the globe into a war zone and back. They are the best and brightest that the Air Force has, and if it hadn't been for their bombing missions in Afghanistan and Iraq the troops on the ground would have had to fight alot harder and probably would have lost alot more men.

Quoted: Quoted: Quoted: Quoted: Quoted: *Active center-of-gravity control, which dictated that the FCS be integrated with the fuel system to maintain stability as fuel burned. That will prevent capucinno spills during the mission. You have something against the Air Force? Obviously.  It would do a lot more than "spill a cappuccino" if you had a sudden departure from controlled flight brought on by poor CG management by the Flight Control System.  Yeah, those B-2 pilots are real Gucci Prima Donnas, huh?  40+ hour long flights in a cramped ass cockpit with no crapper, hot food (maybe an MRE or two), or room to stretch out.  Pansies, real men would'nt fly 20,000 mile combat missions.   I just watched a show on the B2 crews recently. They do have toilets on the plane, and they do have a cot on the plane that the pilots take turns taking naps in. I'm not saying they have it soft at all. They fly the most sophisticated airplane ever made across the globe into a war zone and back. They are the best and brightest that the Air Force has, and if it hadn't been for their bombing missions in Afghanistan and Iraq the troops on the ground would have had to fight alot harder and probably would have lost alot more men.

It's a little plastic chemical toilet, not a full lav like the luxurious C-17.    The "cot" is, like Andy said a little folding lounger, or thermarest, or whatever they bring with them, not a nice bunk like the C-17 (or C-5, or C-130, or KC-135, or....).  The point is, its not built for comfort, ever been in the cockpit of one?  There's not much room there!

COLE-CARBINE:  Thanks for the post.

That is quite interesting.  I haven't thought of it recently but the technology for the B2 was SotA in the early 1980s.  Personally for me I would be wondering, would the B2 see as many years of service as the venerable B52 that built in the mid-1950s?

Quoted: . . The only thing our engineers ( at my company ) can do is ask mommy to tie their shoelaces.   Save one, and that one is a woman....and she is so mind numbingly brilliant it's amazing....and more competant than any man that has ever worked at my company.

The human capital has been one item in the USofA economy that has been drastically wasted.  One day you may need thousands of engineers, and the next day you maybe firing thousands of engineers.  One you need the people with that type of technical expertise, you need them now and you need them bad, but when you don't need them, they are tossed away like yesterday's old toys.  Many of these engineers that was laid-off have moved on and their knowledge was lost, even though all of the aerospace firms document to the max, they will suffer a type of "corporate alzheimers" disease.

Quoted: Quoted: . . . Many of these engineers that was laid-off have moved on and their knowledge was lost, even though all of the aerospace firms document to the max, they will suffer a type of "corporate alzheimers" disease.

Old documentation is the next best thing to throwing the information away.  Old reports usually contain no more than was required to satisfy a contract, the really good internal test reports are lost in storage and there is no master index that can be searched anyway; the engineers tote the most useful stuff from job to job in cardboard boxes, and when they retire it either gets left in the cabinet or tossed, or rarely, inherited by someone that's staying a while.

It's pitiful, and the amount of data that is lost ought to cause an outrage, but, the .gov will pay to recreate the info on the next contract, so the incentive to recycle is low.  In fact, it's illegal in some cases.  The storage costs are also high, so manufactuer's have incentive to toss old reports.

Quoted: At least it's a flushing camping toilet… A step up from this old C-130 horror… www.oswaldbailey.co.uk/PIX/BIG/593069.jpg

The good old "honey bucket", what a nice invention that is.  

We have a couple of those in the back of the C-17, for pissing only.  Some of the foreign nationals we haul around the AOR don't get that though.  

What about the electrogravitic drive?

Quoted: Legacy of B-2 Bomber Innovations Apparent in J-UCAS and Other Programs   By William B. Scott   *Designing and building all-composite skins and structures--the first aircraft to use composites so extensively. This challenge was considered so risky that, for a while, a second team was set up to design an aluminum wing in parallel. A metal structure would have been much heavier, greatly reducing the B-2's range-payload capability. Thus, a considerable effort was devoted to developing a composite version, and it paid off; the aluminum-wing option was dropped before the first Preliminary Design Review took place. "Today, [developing a composite wing] seems straightforward, because the world's used to composite vehicles. But it was a big deal then," Myers notes.

This paragraph ends with a major statement of total BS!

Quoted: "Today, [developing a composite wing] seems straightforward, because the world's used to composite vehicles. But it was a big deal then," Myers notes.

This is totally FALSE! There is NO composite wing developed or in development today that "seems straightforward". It STILL is a BIG DEAL today. Composite wing structures are very complicated to design for manufacturing and maintenance. Have you been to the U.S. Air Force Museum and looked closely at the huge (and sloppily done) composite PATCHES that are on the bottom of the B-2 wing's surface!?!?!? They called the composites in the B-2 "black aluminum" because the only weight savings is from the lack of rivets used to hold the structure together. The composite materials themselves DO NOT allow for much weight savings...that problem is still being solved as week speak!

Fact: Every manned military light/medium/heavy transport, refueler, bomber, attack, and fighter aircraft in service today, with the exception of the B-2, F-117, and (I think) the F-22 have ALUMINUM WINGS!

Fact: Every civilian airliner or air transport flying today has ALUMINUM WINGS! (Some of these wings have composite secondary structure, but the primary wing is alumnimum.)

The only all-composite wings on aircraft flying today are on small 1-5 place private GA aircraft, experiemental aircraft, UAV's and a small number of executive-type aircraft and business jets.

The Boeing 787 Dreamliner will be the FIRST airliner to have COMPOSITE WINGS and a COMPOSITE FUSELAGE. First flight estimated to be in 2007.

$0.02,
AE

Quoted: Quoted: Legacy of B-2 Bomber Innovations Apparent in J-UCAS and Other Programs   By William B. Scott   *Designing and building all-composite skins and structures--the first aircraft to use composites so extensively. This challenge was considered so risky that, for a while, a second team was set up to design an aluminum wing in parallel. A metal structure would have been much heavier, greatly reducing the B-2's range-payload capability. Thus, a considerable effort was devoted to developing a composite version, and it paid off; the aluminum-wing option was dropped before the first Preliminary Design Review took place. "Today, [developing a composite wing] seems straightforward, because the world's used to composite vehicles. But it was a big deal then," Myers notes. This paragraph ends with a major statement of total BS! Quoted: "Today, [developing a composite wing] seems straightforward, because the world's used to composite vehicles. But it was a big deal then," Myers notes. This is totally FALSE! There is NO composite wing developed or in development today that "seems straightforward". It STILL is a BIG DEAL today. Composite wing structures are very complicated to design for manufacturing and maintenance. Have you been to the US Air Force museum and looked closely at the huge (and sloppily done) composite PATCHES that are on the bottom of the B-2 wing's surface!?!?!? They called the composites in the B-2 "black aluminum" because the only weight savings is from the lack of rivets used to hold the structure together. The composite materials themselves DO NOT allow for much weight savings...that problem is still being solved as week speak! Fact: Every manned military light/medium/heavy transport, refueler, bomber, attack, and fighter aircraft in service today, with the exception of the B-2, F-117, and (I think) the F-22 have ALUMINUM WINGS! Fact: Every civilian airliner or air transport flying today has ALUMINUM WINGS! (Some of these wings have composite secondary structure, but the primary wing is alumnimum.) The only all-composite wings on aircraft flying today are on small 1-5 place private GA or experiemental aircraft and UAV's. The Boeing 787 Dreamliner will be the FIRST airliner to have COMPOSITE WINGS and a COMPOSITE FUSELAGE. First flight estimated to be in 2007. $0.02, AE

I agree entirely with what you are saying, but the "B-2" at the AF museum was never a flying aircraft, its only a ground mockup.  The 21 actual B-2s have much nicer surfaces.  

Quoted: Quoted: Quoted: . . . Many of these engineers that was laid-off have moved on and their knowledge was lost, even though all of the aerospace firms document to the max, they will suffer a type of "corporate alzheimers" disease. Old documentation is the next best thing to throwing the information away.  Old reports usually contain no more than was required to satisfy a contract, the really good internal test reports are lost in storage and there is no master index that can be searched anyway; the engineers tote the most useful stuff from job to job in cardboard boxes, and when they retire it either gets left in the cabinet or tossed, or rarely, inherited by someone that's staying a while. It's pitiful, and the amount of data that is lost ought to cause an outrage, but, the .gov will pay to recreate the info on the next contract, so the incentive to recycle is low.  In fact, it's illegal in some cases.  The storage costs are also high, so manufactuer's have incentive to toss old reports.

I guess when you spending other people's hard earned money, it matter's little.  I guess with this type of attitude, it will come back to bite them in the @ss.

Quoted: Quoted: Legacy of B-2 Bomber Innovations Apparent in J-UCAS and Other Programs   By William B. Scott   *Designing and building all-composite skins and structures--the first aircraft to use composites so extensively. This challenge was considered so risky that, for a while, a second team was set up to design an aluminum wing in parallel. A metal structure would have been much heavier, greatly reducing the B-2's range-payload capability. Thus, a considerable effort was devoted to developing a composite version, and it paid off; the aluminum-wing option was dropped before the first Preliminary Design Review took place. "Today, [developing a composite wing] seems straightforward, because the world's used to composite vehicles. But it was a big deal then," Myers notes. This paragraph ends with a major statement of total BS! Quoted: "Today, [developing a composite wing] seems straightforward, because the world's used to composite vehicles. But it was a big deal then," Myers notes. This is totally FALSE! There is NO composite wing developed or in development today that "seems straightforward". It STILL is a BIG DEAL today. Composite wing structures are very complicated to design for manufacturing and maintenance. Have you been to the U.S. Air Force Museum and looked closely at the huge (and sloppily done) composite PATCHES that are on the bottom of the B-2 wing's surface!?!?!? They called the composites in the B-2 "black aluminum" because the only weight savings is from the lack of rivets used to hold the structure together. The composite materials themselves DO NOT allow for much weight savings...that problem is still being solved as week speak! Fact: Every manned military light/medium/heavy transport, refueler, bomber, attack, and fighter aircraft in service today, with the exception of the B-2, F-117, and (I think) the F-22 have ALUMINUM WINGS! Fact: Every civilian airliner or air transport flying today has ALUMINUM WINGS! (Some of these wings have composite secondary structure, but the primary wing is alumnimum.) The only all-composite wings on aircraft flying today are on small 1-5 place private GA or experiemental aircraft and UAV's. The Boeing 787 Dreamliner will be the FIRST airliner to have COMPOSITE WINGS and a COMPOSITE FUSELAGE. First flight estimated to be in 2007. $0.02, AE

Years ago, before Hughes Space & Communication of Culver City became part of Pratt & Whitney, the company was nice enough to give the friends and family a tour of the facilities in Culver City Calif(about 10 miles s. of Los Angeles), and saw very extremely light-weight graphite compositions.  I guess the state of the art hasn't progressed to the point where they can be used for wing surfaces.

Quoted: I agree entirely with what you are saying, but the "B-2" at the AF museum was never a flying aircraft, its only a ground mockup.  The 21 actual B-2s have much nicer surfaces.

Yes, you are correct. The AF Museum's B-2 is a non-flying testbed.

The problem of repairing composite wings and surfaces is big one and we have much more to learn about repair and maintenance of these structures.

The nice thing about aluminum is you can replace the rivets and metal panels relatively quickly and be back in the air. Composites pose bigger problems and the solutions to damages to these structure are still being studied and developed. There are boron pacthes and other repairs, but there is still a long way to go in the field of composite damage repair.

Quoted: Years ago, before Hughes Space & Communication of Culver City became part of Pratt & Whitney, the company was nice enough to give the friends and family a tour of the facilities in Culver City Calif(about 10 miles s. of Los Angeles), and saw very extremely light-weight graphite compositions.  I guess the state of the art hasn't progressed to the point where they can be used for wing surfaces.

The big problem is not so much the materials themselves, though there are always going to be improvements in materials. The big problem is how to manufacture and configure the wing so you optimize the properties of the materials.

You can have the strongest, lightest material in the world, but if you can't design a structure that makes efficient use of its properties, then your structure won't be as wonderful as Popular Mechanics tells you it can be...

Quoted: Quoted: Legacy of B-2 Bomber Innovations Apparent in J-UCAS and Other Programs   By William B. Scott   *Designing and building all-composite skins and structures--the first aircraft to use composites so extensively. This challenge was considered so risky that, for a while, a second team was set up to design an aluminum wing in parallel. A metal structure would have been much heavier, greatly reducing the B-2's range-payload capability. Thus, a considerable effort was devoted to developing a composite version, and it paid off; the aluminum-wing option was dropped before the first Preliminary Design Review took place. "Today, [developing a composite wing] seems straightforward, because the world's used to composite vehicles. But it was a big deal then," Myers notes. This paragraph ends with a major statement of total BS! Quoted: "Today, [developing a composite wing] seems straightforward, because the world's used to composite vehicles. But it was a big deal then," Myers notes. This is totally FALSE! There is NO composite wing developed or in development today that "seems straightforward". It STILL is a BIG DEAL today. Composite wing structures are very complicated to design for manufacturing and maintenance. Have you been to the U.S. Air Force Museum and looked closely at the huge (and sloppily done) composite PATCHES that are on the bottom of the B-2 wing's surface!?!?!? They called the composites in the B-2 "black aluminum" because the only weight savings is from the lack of rivets used to hold the structure together. The composite materials themselves DO NOT allow for much weight savings...that problem is still being solved as week speak! Fact: Every manned military light/medium/heavy transport, refueler, bomber, attack, and fighter aircraft in service today, with the exception of the B-2, F-117, and (I think) the F-22 have ALUMINUM WINGS! Fact: Every civilian airliner or air transport flying today has ALUMINUM WINGS! (Some of these wings have composite secondary structure, but the primary wing is alumnimum.) The only all-composite wings on aircraft flying today are on small 1-5 place private GA aircraft, experiemental aircraft, UAV's and a small number of executive-type aircraft and business jets. The Boeing 787 Dreamliner will be the FIRST airliner to have COMPOSITE WINGS and a COMPOSITE FUSELAGE. First flight estimated to be in 2007. $0.02, AE

AE,

What about the great potential offered by the new material called "metal rubber?"  Flexible wings and that sort of thing.

Justin

Quoted: One for the 'old man'… www.csulb.edu/colleges/coe/ae/ae_dept/news/AIAA%20X36%20flyer%201.jpg

Pretty good looking, if I do say so.  

I wonder who David Manley might be; he's no one ever associated with the program while in progress.  On the other hand, we've passed out cups, jackets, and patches to every Joe in sight - you would think we had 1000 people on the job.

Quoted: AE, What about the great potential offered by the new material called "metal rubber?"  Flexible wings and that sort of thing. Justin

I'll jump in here, even though the question isn't directed to me, having a fair bit of practical experience with this technology.  That's the first time I've see "rubber metal" used; pretty funny.


Vought Aircraft and McDonnell Douglas started working on "Conformable Moldline Technologies" in the 90's; Vought is the real father of the technology, co-opted by MDC after they partnered with us on a contract.

We have done thousands of hours of design and testing in St. Louis, ...

And now that I think about disclosure, I'm going to stop, except to add that it will be interesting to see which stiffening technology other contractors use.  We'll be able to detect BS rapidly.

Quoted: Quoted: Quoted: One for the 'old man'… www.csulb.edu/colleges/coe/ae/ae_dept/news/AIAA%20X36%20flyer%201.jpg Pretty good looking, if I do say so.   I wonder who David Manley might be; he's no one ever associated with the program while in progress.  On the other hand, we've passed out cups, jackets, and patches to every Joe in sight - you would think we had 1000 people on the job. Amazingly 'cheap' program too! Something like only $60 million wasn't it? Of course if you had charged the US DoD $6,000 Million you might have been in with a shout… ANdy

BoP was a good investment fo the company.  $60 million sounds like a bunch of money for an airplane that is no more than a glorified jet powered homebuilt with an ejection seat (heck, I signed off one assembly with a bicycle part), but there is more to it than meets the eye, and the real payoff is in the access we gained and the signal sent to Northrop and LM; those footsteps they hear aren't behind them.