North American XB-70 Valkyrie

The XB-70 Valkyrie was envisioned as a long-range, high-altitude triplesonic experiment in flight, capable of Mach 3 at 74,000 feet at a time when fighter aircraft one-tenth its weight could barely reach doublesonic speeds.
Conceived with high hopes in 1954, only two prototypes were ever completed-one of which crashed during flight testing, killing the crew.
But though considered obsolete before it ever left the ground, the Valkyrie gave birth to a whole family of innovative technologies-advances in materials and methods that made possible the B-1, B-2 and F-117 A.
In North AmerIcan XB-70 ValkyrIe, aviation historian Steve Pace tells the complete story of this ill-fated aircraft, from its development as the most promising successor to the 8-52 to its eventual abandonment 15 years later in the face of changing military priorities.
Explore the XB-70A's high-speed, high-temperature design.
Meet the people behind the airplane: engineers, officers, designers, pilots, and more.
See new photographs of everything from cockpit to landing gear.
And learn about a third XB-70 prototype that was never completed.
You'll find all of this and more, in this new edition of North American XB-70 Valkyrie.

VALKYRIE – North American’s Mach 3 superbomber

It is one of the icons of modern aviation, which is curious considering only two were built and they flew just
129 times.
However, like the Maiden it was named for, the Valkyrie awed those around it.
Beautiful in form, and almost unbelievable in function, the B-70 would have been the ultimate incarnation of Curtis LeMay's vision of a strategic bomber.
The half-million-pound aircraft was capable of flying over 2,000 miles per hour at altitudes in excess of 70,000 feet, and doing it for hours at a time.

Fantastic as the Valkyrie appeared, it was not to be.
The political and fiscal climate that existed during the 1960s strangled then killed the aircraft almost before it was born.
There were, of course, other reasons.
Intercontinental ballistic missiles became feasible, and were considered - perhaps incorrectly - to be a deterrent force that was less expensive to build and maintain.
The Soviet Union, the only real target for the bomber, was developing surface-to-air missiles and interceptors that might have been capable of defeating the aircraft.
But ultimately it was Robert McNamara and his Whiz Kids who reduced the program to a pair of technology demonstrators and dismissed the manned bomber as a viable weapon.

This is the story of the largest Mach 3 aircraft ever flown: the North American Aviation XB-70A Valkyrie. Dennis R. Jenkins and Tony R. Landis have conducted extensive research in military, NASA, and company archives to find previously uncovered aspects of this fascinating program.
Included are descriptions of the proposed bombing and navigation systems, defensive armament, electronic countermeasures, and early attempts at stealth technology.
Accompanied by over 500 photos and dozens of illustrations, this in-depth history covers the entire B-70 program, not just the two aircraft that were ultimately manufactured.

Foreword

In 1955, North American Aviation, Incorporated, and The Boeing Company were requested by the United States Air Force to submit competitive bids for Veapons System 110A.
Both proposals were rejected by the Air Force, and the companies were "sent back to the drawing board. " With a completely new design, in December 1957 North American was finally selected as the winner and awarded a contract to build the B-70.
The proposal was for an airplane capable of flying from bases in the United States to any ranger in the Soviet Union at Mach 3 and 70,000 feet, carrying a 25,OOO pound payload, with the ability to recover to a base in friendly territory.
It was a proposal that required the designers to use concepts that were at the extremes of aircraft technology.
At that time, I was chosen to be the project pilot for the flight test program.
After the contract was awarded by the Air Force, it was the task of engineering and manufacturing personnel to coordinate with the designers to build this remarkable airplane.
At a time when aluminum was used extensively in the construction of airplanes, stainless steel and titanium had to be used for most of the XB-70 to withstand the temperatures that aerodynamic heating would generate at Mach 3.
Stainless steel honeycomb panels were used for most of the skin of the airplane.
The task was enormous, but it was only one of many to be accomplished so that this airplane could meet its speed, altitude, range, and payload requirements.
The result was a magnificent airplane.
Originally, it has been intended as the next generation of heavy bomber for the Strategic Air Command, but was ultimately relegated to use as a research aircraft.
Four years before the first flight of the airplane, a fixed-base simulator was built and the first task was re optimize the flight control system.
Simulators are used in engineering departments primarily as development tools, not as pilot training devices, but in this case, I learned a lot about the handling qualities of the airplane while participating in these development tests.

When construction was completed, the airplane was towed to the run-up pad for systems checkout.
The pilots had attended a ground school on aircraft systems provided by the engineering departments at North American, and had flown the fixed-based simulator for many hours.
Now we would run the engines and participate in the system checkout programs as final preparation for the first flight.
The maintenance and engineering personnel were faced with many new problems,
but worked around the clock to get the airplane ready to fly.
Flying the airplane was probably the easiest job of all.
The pilots were well prepared.
Granted, there were some unknowns, and some surprises that required quick decision-making, but that is not unusual in the initial test flights of any aircraft .
The first takeoff went as planned, but was followed by failure of the landing gear to retract properly, a runaway engine, and a failure of the brake system causing a couple of blown tires. In spite of that, the flight was deemed successful.
It was the beginning of a flight test program that was successful.
Ship #1 (2OOO1) flew at Mach 3 for the first time on its 17th flight - the largest and heaviest aircraft to have ever flown that fast.
The final milestone for the program was to fly at Mach 3 for 30 minutes since it was predicted that all of the temperatures in the airplane would have stabilized at that time.
Ship #2 (20207) flew at Mach 3 for 32 minutes on its 39th flight.
Considering all of the new concepts in the airplane – folding wingtips, huge variable area inlet ducts, canard surface with flaps, 4,000-psi hydraulic systems, a moveable windshield, and a variety of frustrating problems that arise in an airplane this complex - it was remarkable that it accomplished the goals of the program without any optimization.
It continued to fly at a rate of about one flight per week for all the time I was on the program. That is a testimony to the maintenance and engineering people who had resolve the problems and get it ready to fly again.
The airplane was awesome when first viewed, but in my judgment, it was an easy airplane to fly - and an experience I will never forget.

Alvin S. White
Pilot, first flight of the XB-70A
North American Chief Test Pilot/XB-70 Project Pilot

Foreword

I was privileged to be assigned to the XB-70 program about two years prior to the first flight. Al White, Colonel Joe Cotton, Van Shepard, and I went to XB-70 ground school, flew engineering simulators, and participated in all kinds of engineering studies and tradeoffs.
We (the Air Force) felt that it was very important for all of the pilots to have large airplane experience and that we flew together as much as possible.
The two airplanes that were selected as training airplanes for the XB-70 pilots were the B-52 and B-58.
The B-52 was used to get recent big airplane experience and the B-58 was used to get
supersonic experience.
The B-58 that was assigned was a TB-58, which had tandem cockpits with dual controls.
The B-58 had near identical takeoff and landing speeds to the XB-70.
We were able to develop crew coordination and practice some of the maneuvers and
tests planned for XB-70 missions.
White and Cotton flew all the early XB-70 flights with Shepard and myself flying as chase pilots.
We used the B-58, F-104, and T-38s as chase airplanes.
The B-58 was an excellent supersonic chase airplane.
It could stay with the XB-70 us to Mach 2 and had long flight duration.
The B-58 was used as a chase airplane for about the first 3O flights.
It never missed a takeoff.
My first XB-70 mission was as copilot on the sixth flight.
My next mission was on the 12th flight where we had a structural failure of the wing apex while accelerating past Mach 2.60 for the first time.
That resulted in severe damage to engines numbers 4, 5, and 6.
One of my most enjoyable missions was when I piloted the number two airplane to Carswell AFB at Fort Worth for an "Air Force Convention" meeting.
We cruised at Mach 2.60 at 64,00 feet.
The time from takeoff to over the field at Carswell was 59 minutes.

I would not consider the XB-70 to be a difficult airplane to fly, but it did require the pilots to be very knowledgeable of all the system and the emergency procedures.
Landing gear, brakes, and hydraulic systems were a cause of some concern up through the end of the program.
The steel honeycomb structure required many repairs, especially when exposed to the high ,"-temperatures that resulted from flying at or near Mach 3.
The maintenance and engineering personnel working on the program were the cream of the crop.
The North American Aviation, General Electric, Air Force, and NASA personnel were some of the best I have ever worked with.
The two-airplane program went on to complete 129 flights, and I was fortunate to fly on 63 of them.
Most of the flights resulted in happy times but the loss of Major Carl Cross and Joe Walker when the F-104 and number two XB-70 collided was a sad day for the program.
Another sad day was when a defueling truck exploded, due to static electricity, while under the XB-70 wing.
One North American mechanic was killed and another had his life greatly shortened because
of severe injuries.
There were some heroic actions taken by North American Aviation and Air Force mechanics to prevent further injuries and the loss of that XB-70.
NASA took over the test program after the accident of the number two airplane and the F-104. Lt. Colonel Emil "Ted" Sturmthal and NASA pilot Don Mallick were trained on the XB-70 and participated in the 34 flights flown during the remainder of the program.
The last flight was flown from Edwards AFB to Dayton, Ohio, with Sturmthal as my copilot. Mallick, in the B-58, escorted us all the way.
The final flight was flown at Mach 0.92 (about 600 mph) and 29,000 feet.
We were being very conservative since the test program was over and our only objective was to deliver the airplane to the Air Force Museum.
We did not want to run the risk of having to land some other place.
We arrived at Dayton and made a flight down the runway.
I made the last landing in the airplane, taxied to the ramp, and shut down the engines.
I then presented the airplane paperwork to the museum director.
He signed the receipt for the airplane, and the delivery was complete.

Fitzhugh L. Fulton, Jr,
Pilot, last flight of the XB-70A
Lieutenant Colonel, USAF (Ret.)/NASA Flight Research Center

Preface
When one thinks of Mach 3 aircraft, what generally comes to mind is the Lockheed SR-71 or perhaps the MiG 25.
But there was another Mach 3 design, one that was a good deal larger and five times heavier than the Blackbird or the Foxbat.
Perhaps even more futuristic looking, the North American Aviation XB-70A Valkyrie was the culmination of General Curtis LeMay's quest for the ultimate strategic bomber.

The beginning of the XB-70A story is intertwined with the development of a nuclear-powered bomber - something that could only have been imagined during the 1950s - and a new Mach 3+ interceptor, the F-108 Rapier.
All three of these programs were intended to share systems and components, largely as a
cost-cutting measure, and the funding nightmare soon unraveled as first the nuclear-powered bomber, then the F-108, were cancelled.
Today, the popular conception of a strategic bomber is the Boeing B-52 Stratofortress.
A product of the 1950s, the B-52 recently made the nightly news while carpet-bombing
the Taliban in Afghanistan.
But what is often overlooked, especially 50 years later, is that the B-52 was the second in a line of "interim" bombers.
The first was the Convair B-36, a project begun when it was feared that World War II would need to be conducted entirely from bases within North America.
The resulting aircraft was something of a technical triumph, but it was still a piston-powered aircraft born into the beginning of the jet age.
Almost as soon as the aircraft appeared, the Strategic Air Command (SAC) began planning to replace it with the newer B-52.
But the B-52 was also born at an awkward time.
Although the aircraft that eventually emerged was blessed with swept wings and jet engines - resulting in a bomber that cruised almost twice as fast as the B-36 – it was still a subsonic aircraft at a time when the Air Force desperately wanted to go supersonic.
The first supersonic bomber - the Convair B-58 Hustler - was an outgrowth of the preliminary studies that eventually led to the B-70.
Sleek looking and fast, it was, at best, a medium bomber.
As events turned out, the B-58 - magnificent as it was - became a maintenance nightmare, pushing the state-of-the-art a little too far.
Its tenure was very brief.

What Curtis LeMay wanted was an aircraft with the range and payload capabilities of the B-52 and the speed of the B-58.
Initially, the replacement for these bombers was to be split between a futuristic nuclear-powered bomber (WS-125A) and a more conventional aircraft (WS-110A) that used a new high-energy fuel.
When these programs began to lag due to technical challenges and funding difficulties, the "interim" B-52 was supplemented with an "improved" B-52 that eventually emerged as the B-52G/H.
There was, however, a dark horse that had been largely dismissed by the user command (SAC), but was high prized by the development commands (ARDC and AMC) and the politicians.
The intercontinental ballistic missile (ICBM) was thought to be decades from operations.
Then, rather suddenly, break-throughs that resulted in smaller thermonuclear weapons and reliable guidance systems allowed the Atlas and Titan to be deployed much sooner than had been expected.
Manned bombers now appeared - at least to some - to be redundant.

The demise of the WS-125A was a mixed blessing for the B-70 program.
It left the Valkyrie as the only manned strategic system under development, helping it gain priority.
But the loss of a second funding source for shared systems made the B-70 appear to overrun its budget.
The cancellation of the F-108 exasperated this appearance.
The deployment of workable ICBMs was the death blow.
Changing political and budgetary climates at first killed the program, then brought it back to life as a two-vehicle test program - sort of a sheep in wolf's clothing.
Regardless, when the Valkyrie finally flew, it was truly awe-inspiring.
Minor technical glitches plagued the program early on, but eventually the aircraft routinely flew at its Mach 3 design speed.

Then tragedy.
Air Vehicle 2 was lost in a midair collision during a staged photo shoot after returning from a test flight.
XB-70A pilot Al white survived, but copilot Carl Cross, along with F-104 pilot Joe Walker, died in the accident.
The program would continue to fly for a while using Air Vehicle 1, but the end was in sight for the largest Mach 3 aircraft ever built.
Today the single remaining aircraft is housed at the Air Force Museum in Dayton, Ohio -
just as awe-inspiring as the day she was rolled out in Palmdale , California,40 years ago.

Che Spettacolo!!!!!!!!!
A quando un super post sul favoloso B70