I’m getting a bit tired of politics and corruption right now. How about some aviation history? This is an interesting article on the crash of the supersonic bomber prototype.
The two test pilots were in the cockpit of a T-38 trainer flying off the left wing of the new XB-70 Valkyrie bomber, aircraft number 62-0207. They just saw the civilian registered NASA F-104N Starfighter of pilot Joe Walker slide upside down across the top of the huge white bomber, shear off both it’s twin tails and skid sideways, then break in two, killing Walker instantly. Behind the XB-70 Walker’s F-104N tumbled end over end, a pinwheel of bright orange flame nearly six hundred feet long tracing its convulsive death spiral.
The flight was a photo shoot for GE which made the jet engines of all the aircraft being photographed.
The fatal error was including an F 104 star fighter which had unreliable handling characteristics in low speed flight.
The poor safety record of the Starfighter brought the aircraft into the public eye, especially in German Air Force service. Fighter ace Erich Hartmann famously was retired from the Luftwaffe because of his protests against having to deploy the unsafe F-104s. The F-104 was also at the center of the Lockheed bribery scandals, in which Lockheed had given bribes to a considerable number of political and military figures in various nations in order to influence their judgment and secure several purchase contracts; this caused considerable political controversy in Europe and Japan.
It was considered a “widowmaker” at low speed especially takeoff and landing.
The F-104 series all had a very high wing loading (made even higher when carrying external stores). The high angle of attack area of flight was protected by a stick shaker system to warn the pilot of an approaching stall, and if this was ignored, a stick pusher system would pitch the aircraft’s nose down to a safer angle of attack; this was often overridden by the pilot despite flight manual warnings against this practice. At extremely high angles of attack the F-104 was known to “pitch-up” and enter a spin, which in most cases was impossible to recover from. Unlike the twin-engined McDonnell Douglas F-4 Phantom II for example, the F-104 with its single engine lacked the safety margin in the case of an engine failure, and had a poor glide ratio without thrust.
The safety record of the F-104 Starfighter became high-profile news, especially in Germany, in the mid-1960s. In West Germany it came to be nicknamed Witwenmacher (“The Widowmaker”). Some operators lost a large proportion of their aircraft through accidents, although the accident rate varied widely depending on the user and operating conditions; the German Air Force lost about 30% of aircraft in accidents over its operating career, and Canada lost 46% of its F-104s (110 of 235). The Spanish Air Force, however, lost none.
The B 70 was an amazing aircraft. My father-in-law walked up the air intake to one engine which he could do without bending over. It was designed to evade interceptors and to carry nuclear weapons at Mach 3 speeds. It first flew in 1964, and the introduction of Soviet anti-aircraft missiles put its mission in doubt.
the B-70 program was canceled in 1961. Development was then turned over to a research program to study the effects of long-duration high-speed flight. As such, two prototype aircraft were built, and designated XB-70A; these aircraft were used for supersonic test-flights during 1964–69. In 1966, one prototype crashed after colliding in mid-air with a smaller jet aircraft; the remaining Valkyrie bomber is in the National Museum of the United States Air Force near Dayton, Ohio.
The crash of the XB 70 was a public relations mishap and cost some people their jobs and two pilots their lives.
Joe Walker has arguably the toughest position in the formation. The little needle-nosed F-104 has stubby wings and a kite tail. It is built for high-speed intercepts, not low speed demonstration formation flight. There are reasons the Thunderbirds never flew the F-104. Some reports suggest Joe Walker questioned the reason for the photo flight, suggesting the formation flight yielded no useable data to contribute to the operational test program.
Walker’s job in the formation is a tough one, even for an outstanding test pilot. He has to keep the flying missile F-104 tightly positioned off the right wingtip of the XB-70 and spaced at a visually pleasing interval between the XB-70 and the F-5A to his right. He will not be able to see the wingtip of the XB-70 behind him unless he cranes his neck uncomfortably to his left rear in his flight helmet and oxygen mask. The high tail design of the F-104 and the drooping right wingtip of the XB-70, lowered into this position to facilitate greater lift for low speed flight, make for another bad combination.
This may have been a time before the vortices from wingtips of large aircraft were understood. That was fatal.
As the aircraft prepare to separate Walker’s controls suddenly feel vague and mushy, as though the plane’s control surfaces have been taken over by some greater force. He is trapped in the swirling vortices tumbling at cyclonic speed off the lowered wingtips of the XB-70.
The needle nose F-104 bucks upward, there is a thud, another buck, and the plane’s nose rears violently upward like a bronco hurling its rider. Walker likely slams his stick forward and right, but it is too late. Physics have taken over.
The photo at the top shows the result as the F 104 disintegrates and takes off both vertical stabilizers of the XB 70. Two pilots are killed and one survives.
Trapped in the whirlpool hurricane of the wingtip vortices from the XB-70, the F-104 rolls inverted to the left, executing a snap roll with the XB-70 wingtip as its axis. Yaw control is lost, and in an instant Walker is turnstiled sideways to the flight path. His body is slammed forward and right into the harness holding him in the ejection seat of the F-104N.
It is over in seconds and is all on film.
The XB 70 crashes in the desert below.
21 thoughts on “The crash of the XB 70 in 1966.”
At extremely high angles of attack the F-104 was known to “pitch-up” and enter a spin, which in most cases was impossible to recover from.
High AoA is when the nose of the plane is pitched upward and the wings and fuselage are pushed forward into the wind, like in the bottom photo. It acts like a brake and bleeds energy very quickly off the aircraft. The F-104 had a very small wing area and so small control surfaces. So it would be unstable in those situations and nearly impossible to correct if it did spin out of control.
Exploring the limits of high AoA flight is required in aircraft flight test programs, the idea being no regular service pilot should ever explore a region of flight in an aircraft that a test pilot hasn’t already explored and documented. Testing the limits of that envelope is what sometimes got test pilots killed at Edwards AFB. The reason being that uncontrolled spins can apply really high G-forces to a pilot and knock them out or so disorient them they can’t function.
The XB-70 was a stunning piece of technology. I seem to recall that stainless steel honeycomb laminates were used on the wings for strength, lightness and heat resistance. Six engines. Mach 3. What a beast that thing was.
F-35 High Angle of Attack Testing: https://youtu.be/mfWHHuLILs0
Some more airplane porn. The SR 71 development.
Another aircraft porn bit. The breakup of an SR 71 at Mach 3.
Third, A giant model SR 71 flying in radio control.
“It acts like a brake and bleeds energy very quickly off the aircraft.”
That was the main part of the maneuver behind John Boyd’s famous ‘Forty-Second Boyd’ challenge where he bet any pilot $40 that he could reverse positions with them in 40 seconds.
Boyd’s energy-maneuverability equation, thrust minus drag over weight multiplied by velocity, determined that the performance of the aircraft depended on how fast it either gained or lost energy.
He was flying an F-100. According to Coram’s biography, the big problem with that plane was adverse yaw. Boyd figured out a workaround and bested the other guys who wouldn’t risk pushing it. The F-104 was fine with yaw, but its T-tail caused the pitch problems.
B-1 Bomber Takeoff (2010): https://youtu.be/9f1A3Wt3OtY
F22 Raptor Take-off at RIAT 2010: https://youtu.be/16ti9GwnlVs
The F-22 At Nellis (2012): https://youtu.be/ipAYrWRcl8E
F/A-18 Demo Farnborough Airshow 2014: https://youtu.be/o00j1i85pGE
Boeing Preps the 787-9 Dreamliner for Farnborough (not CGI): https://youtu.be/GZRKm6PG918
The F-100 Super Sabre was famous for becoming unstable in ground effects and doing what pilots – the one’s who survived – called the Sabre Dance.
There is still at least one F-104 flying:
Was whoever was in charge of this shambles put in front of a firing squad?
I saw an F-104 fly at an airshow a few years back. I was up close to the runway when he did a low pass on afterburner. Shock diamonds were visible in the 30 foot exhaust flame under bright sun. What a beautiful aircraft. So sleek.
There were a lot of beautiful aircraft in those days. The X 15 should have been the shuttle.
All it needed was the commitment to do it,
Engle credits the X-15 for laying the foundation for many of the operational techniques of the space shuttle, and for providing designers with confidence that certain design and control concepts for the winged orbiter would work:
With similar flying characteristics, the X-15 proved the shuttle could re-enter the atmosphere and glide to a precision landing, in part relying on a maneuver known as Terminal Area Energy Management where speed and altitude are carefully controlled so the vehicle can reach the runway instead of falling short or overflying it.
Using technology developed and tested on the X-15, pilots learned how to transition control smoothly from reaction control jets at high altitudes or in space to wing- and tail-mounted control surfaces in the atmosphere closer to the ground.
While not a benefit to the space shuttle alone, the X-15 was the first flight test program to make extensive use of simulators to work out certain problems and train pilots before going up-a practice since employed for nearly every flight test program.
The X-15 flights proved the usefulness of having chase aircraft follow a test vehicle during its approach to the runway to make sure, as Engle put it: “Everything that is supposed to be up is up, and everything that is supposed to be down is down.”
The X-15 was suggested in the early 1950s by Bell Aircraft’s Walter Dornberger as a vehicle for exploring the realm of hypersonic flight, which was defined as a speed in excess of Mach 5, or five times the speed of sound. The earliest days of the X-15 program were shaped by the National Advisory Committee for Aeronautics, the federal agency which NASA replaced in 1958.
It could have been.
The DD 558 was the pioneer.
The eventual D-558-3 design, which was never built, was for a hypersonic aircraft similar to the North American X-15.
When it became obvious that the D558-1 fuselage could not be modified to accommodate both rocket and jet power, the D558-2 was conceived as an entirely different aircraft. A contract change order was issued on 27 January 1947 to formally drop the final three D558-1 aircraft and substitute three new D558-2 aircraft instead.
I was working for Douglas in 1959.
The three aircraft gathered a great deal of data about pitch-up and the coupling of lateral (yaw) and longitudinal (pitch) motions; wing and tail loads, lift, drag and buffeting characteristics of swept-wing aircraft at transonic and supersonic speeds; and the effects of the rocket exhaust plume on lateral dynamic stability throughout the speed range. (Plume effects were a new experience for aircraft.) The number three aircraft also gathered information about the effects of external stores (bomb shapes, drop tanks) upon the aircraft’s behavior in the transonic region (roughly 0.7 to 1.3 times the speed of sound). In correlation with data from other early transonic research aircraft such as the XF-92A, this information contributed to solutions to the pitch-up problem in swept-wing aircraft.
Those were the days. My first date with my first wife wound up being an evening with her father, who worked for Hughes Aircraft Company, talking about the U2 and all the stuff we knew about airplanes. We never did go out to dinner. She and her mother fixed dinner for all of us. We were married a year to the day after that first date. She told me I was the first young man she had ever brought home that he liked. I liked both of her parents for years after we divorced. We were friends until they both died.
If she had been willing to go along with my ambitions for an academic career in surgery, we might be married still. Two friends from the same era are still married. He is a well known professor.
At least it got the B-70 cancelled.
“At least it got the B-70 cancelled.”
It had already been cancelled. The shootdown of the U2 accomplished that. These planes were prototypes for an SST, possibly.
If I’m not mistaken Clay Lacy was flying the Learjet that chronicled this.
Have an internet friend who is a retired Air Force test pilot, and he told a wonderful follow up story to this.
Some years later he had to be at Wright Patterson AFB, and after work was walking around the museum. He noticed a solitary older man just sitting by himself looking at the sole XB-70.
It was Al White, the surviving pilot of the Valkyrie.
I guess it was the XB-70 that caused the Russians to develop the MiG 25, a very fast fuel sucking interceptor.
I wonder if the XB-70 would have gone into production had this accident not happened.
>> I wonder if the XB-70 would have gone into production had this accident not happened.
I doubt it. ICBMs were being developed and Kennedy decided that the missiles were a better investment, easier to deliver if necessary, cheaper, and more easily hidden and moved around on submarines. It was probably the right call.
It might have been the prototype of the SST.
Boeing eventually got that contract but it, in turn, was cancelled. The sonic boom issue was a major consideration and they went with the 747 and volume vs speed.
When I served in the Air Force I had many occasion to have TDY’s in the DC area of Boeing…one day while wandering about I had found a small wooden door that lead to the SST containment and boy what an afternoon I had wandering about the many ‘stacks’ of serialized titanium bars and equipment including a handful of the GE engines, holy cow, you could stand up inside the cowls and reach skyward and not touch the top of the cowl…they were huge!!! I ventured into the full scale(left side)model in the room and was amazed at the size of the interior(seating was 2×2 if I remember correctly and wasp shaped) and the crew compartment was very comfortable and well laid out…I pulled the ‘reposition nose’ handle and to my surprise the entire foreward assembly dropped to the takeoff/landing position, scared the hell out of me…the trans sonic wing design amazed me…that was a very memorable day for me and I’ll never forget thinking that Boeing was on the right track ‘in the day’ of SST developement only to be politically squashed, I found this to be true many times over the next few decades within my Boeing Military Flight Test career at Edwards AFB following my military retirement…LT
A comment at that site.
The Air Force has been trying to replace the B-52 for over 50 years, when Curtis LeMay declared it obsolete and on the way out. He was correct in the sense that the missile age has made it impossible for it to fly in non-permissive environments until all air defenses are taken out. Unfortunately, that also goes for every other heavy bomber they subsequently made until the stealth B-2, which evades radar but has an extremely low ready rate because of high maintenance of its complex systems. We also have to use the stealth bomber sparingly because we’re out about $1.4 billion if one does happen to go down.
The USAF keeps learning the same lesson over and over again because they have plans to build the Long Range Strike Bomber over the next ten years. It’s reportedly going to cost a cool $80 billion, but the way things work nowadays you can probably multiply that by 10 for a more accurate total.
Meanwhile, the B-52 sits in the bullpen until January 21, 2017.
I have already said that the B 52 production line should be reopened or recreated if the jigs still exist. They probably don’t but maybe the plans do somewhere and are used for all the upgrades over the years.
The high loss rates of first generation supersonic aircraft was not confined just to the F104 Starfighter. An examination of loss rates of F8 Crusaders, F100 Super Sabres, Mirage III, Mig 19 and Mig 21 aircraft was similar. Furthermore, the loss rates of F104 Starfighters amongst NATO airforces such as Denmark, Canada, Norway were virtually the same as what the Luftwaffe endured. The Luftwaffe though operated about 1,200 Starfighters by the late 1960s which attracted the attention of the mass media everytime a Starfighter crashed. Also, the training of Luftwaffe pilots in the USA where clear flying conditions prevailed was vastly different than the flying conditions experienced in the European air space. The learning curve for all airforces flying first generation supersonic aircraft was steep and often ventured into unknown territory, especially where mission profiles for such aircraft were very much in their infancy.
The X-20 Dyna-Soar was the Air Force’s bid for a piece of manned spaceflight, against NASA’s Mercury-Gemini-Apollo. A reusable space plane–single man, but with plans for bigger versions and specialized designs for different missions. Cancelled around 1963. NASA would take men to the moon and fulfill JFK’s mission. Dyna-Soar was probably the better technological path for Earth orbital missions, but it wouldn’t get us to the moon in time.
The Dyna-Soar had a re-entry cooling system that probably would have eventually failed catastrophically. Unlike capsules that use an ablative heat shield or the thermal tiles of the shuttle, the X-20 had a water wall cooling system.
The internal compartments of the Dyna-Soar were encased in ‘water walls’ which provided passive cooling. These reduced the 980 deg C re-entry equilibrium temperature of the airframe truss structure to 90 deg C and allowed the pressure shells of the compartments to be of conventional aluminum. Cooling systems in the compartments further reduced the maximum internal temperature to 46 deg C.
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