The Lovely Valkyrie

No, I’m not talking about the TAH commenter by that name – though based on her photo in the Member’s Gallery, she indeed qualifies. (smile)  I’m talking about this lovely lady.

 

Valkyrie’s story is IMO worth telling.  I’ll tell it briefly here.

. . .

Most of us have heard of the SR-71 – the USAF’s Mach 3 reconnaissance aircraft that was developed from the CIA’s A-12.  However, at various times the US developed other Mach 3 airframes.  Most of them were experimental platforms only, built to investigate high-speed flight but never intended for production.

However, one of them almost made it to production.  That one was the XB-70 – the Valkyrie.

It was an impressive – and beautiful – aircraft.  Two prototypes were built; each flew above Mach 3.

Fate was to decree that these would be the only two ever built.

Background

The XB-70 program began in the mid-1950s.  It was originally designated WS-110A by the USAF.

The initial USAF request for proposals was for a subsonic system with a 4,000nm combat radius, a 50,000 lb payload, and having a 1000nm “maximum possible speed” dash-to-target capability.

The USAF received multiple initial design proposals which, to be blunt, bordered on the absurd.  Here’s a diagram of the original WS-110A proposal from North American Aviation (NAA), the XB-70’s eventual builder.  The Boeing proposal was similarly odd.

 

For comparison purposes, the “floating panels” in the NAA design that would be jettisoned prior to the supersonic dash to target were approximately the size of a B-47.   About these proposed designs, then SAC commander Gen. Curtis Lemay reportedly remarked:  “That’s not an airplane, it’s a 3-ship formation.”

The USAF rejected this initial group of proposals, but did not terminate the WS-110A program.  Since the state of the art in supersonic flight had advanced substantially since the original request for proposals had been released, the USAF revised the requirements to specify a Mach 3 cruise capability and requested a second round of proposals.

A second group of very different proposals were submitted.  The winning proposal, by NAA, was the to become the XB-70.  It featured several novel features:

• the use of high-energy fuels (a mixture of kerosene-based and borane-based fuels (termed “high energy fuels” – AKA HEF or “zip fuels” – which provided approximately 40% more fuel by weight and volume than standard jet fuels) in its afterburners;
• the use of compression lift;
• the use of moveable wing sections 20’ long, designed to be lowered during flight to either 25 degrees below horizontal (300kts to low supersonic) or 65 degrees below horizontal (high supersonic) in order to trap more of the aircraft’s shock wave and enhance the compression lift effect (these were reputedly the largest moveable aircraft control surfaces ever built); and
• an aircraft skin constructed out of two thin layers of stainless steel brazed to a stainless-steel honeycomb structure formed from stainless steel approximately 0.02” thick (titanium was to be used only in extreme high-temperature areas such as the nose, “splitter” [the pointed peak in front of the air intakes], leading wing edges, and exhausts; titanium made up less than 10% of the XB-70s structure).

Contract Award – and Program Cancellation

The contract for construction of the B-70 was awarded in January 1958.  The planned system received the “B-70” designation.  Its name “Valkyrie” was chosen in an USAF “Name the Bomber” contest shortly afterwards.

Problems for the program began even before the contract was awarded.  There were four major ones.

First:  not long after the B-70’s contract was awarded, the USAF terminated its HEF program.  This was not fatal – it reduced the projected payload and range for the planned production B-70s, but conversion of one of the two planned bomb bays mitigated the effect.   Better kerosene-based fuel (JP-6) helped, and weapons design improvements (making them lighter) made the loss in payload capacity acceptable.

Still, the range of the craft was reduced substantially.  Without HEF, aerial refueling would be a necessity.

Second:  the B-70 was designed as a high-altitude, high-speed platform.  Unfortunately, a little development had occurred since the USAF first asked for WS-110A proposals.

That “little development” was called “surface to air missiles”, or SAMs.  By the late 1950s, SAMs could easily reach the XB-70s altitude.

The Valkyrie was huge – nearly 190’ long, with a wingspan of 110’ and a height of over 30’.  Given its stainless-steel skin and physical configuration, there was no way to make it stealthy in the least.  (The A-12 and SR-71 had a much better design in that respect, incorporating composite materials in critical areas, radar-absorbing paint, and a shape that reduced its radar reflection by an order of magnitude over a more conventional aircraft design with the same aerodynamic performance.)

Further:  if a nuclear weapon was used in a SAM, well, getting a SAM “close enough” for a knockdown became relatively easy.

To survive in the early/mid 1960s, strategic bombing changed tactics.  Because of the high-altitude SAM threat, bombers would need to use low-level penetration tactics.  (Indeed, because of the magnitude of the SAM threat to manned bombers the US was moving was away from reliance on manned bombers to missile systems for its primary nuclear deterrent.)  And at low altitudes, the B-70 would only fly at subsonic speeds – indeed, it would not fly significantly faster at low altitude than did the B-52.

Third, the newly elected President Kennedy found out that the alleged “bomber gap” of the late 1950s was in fact a myth, and did not exist.  Both Kennedy and Nixon had been proponents of the B-70 during the 1960 election campaign – Kennedy as a way to attack Nixon with criticism that the Eisenhower administration in which Nixon had been VP had been “soft on Defense” (Eisenhower didn’t want the B-70), and Nixon as a defense against this attack.  Now that he’d been elected POTUS JFK no longer needed to support the B-70 for political reasons.

Finally:  the B-70 program was projected to be extremely expensive.  It would cost substantially more to build B-70s than B-52s, and operating them would be much more expensive than the existing B-52 fleet.

In short, the B-70 program was a weapons system that had become obsolete before its first prototype had even been built.  It was now a wonderful aerial platform – which due to changes in technology and threat now had little or no real military utility.

JFK ordered cancellation of the B-70 as an Air Force weapons system just over 2 months after he was sworn in as POTUS – in late March, 1961.  After some additional wrangling – and despite the efforts of Gen. Curtis LeMay, who was a huge B-70 proponent, to save it – Congress assented.  The B-70 was cancelled.

Research/Test Program

The program was not terminated outright, however.  It was continued as a research program.  The research aircraft were to be designated the XB-70.

Two XB-70 research aircraft were built:  Air Vehicle One (AV-1; tail number 20001), and a somewhat modified version AV-2 (tail number 20207).  A third aircraft was originally planned, but was cancelled during construction.  Its intake tunnel is on display today at the Smithsonian Air and Space Museum.

AV-1 made its first flight on 21 September 1964.  Roughly three weeks later – on 12 October 1964 – it flew supersonic for the first time.  It made unclassified history on 24 October 1964, flying 40 minutes continuously above Mach 1 to set an acknowledged record for sustained supersonic flight.  It made a number of additional flights at Mach 2+, and made its sole Mach 3 flight on 14 October 1965.

Being the first prototype, AV-1 had numerous problems.  Breakup and ingestion of the “splitter” at the apex of the craft’s delta wing (which was immediately front of the aircraft’s intakes) had ruined all 6 of the aircraft’s engines during a flight on 7 July 1965, nearly leading to loss of the aircraft. On its sole Mach 3 flight, AV-1 lost a section of its leading-edge wing skin – with parts again ingested by its huge air intakes, again ruining some of its engines.  Separation of its stainless skin from the underlying stainless honeycomb was determined to be the reason for this latter incident.  As a precaution, AV-1 was restricted to flights at Mach 2.5 or less thereafter.

AV-2 flew for the first time on 17 July 1965.  Though not trouble-free, improvement in fabrication techniques due to experience and lessons learned from AV-1’s troubles (and resulting modifications) meant that AV-2 had many fewer problems.  It made multiple flights above Mach 3.  Unfortunately, this airframe was lost in a mid-air collision with an F-104 during a USAF-sanctioned photo-shoot on 8 June 1966.  The pilot that day, NAA Test Pilot Al White, was able to eject and survived with injuries.  The co-pilot – USAF Maj. Carl Cross, making his first XB-70 flight – did not eject and was killed.  (The pilot of the F-104 that day, NASA test pilot Joseph A. Walker, also died during the collision.)

The remaining XB-70 (AV-1) continued with flight test operations in support of NASA’s National Sonic Boom Program (NSBP) program and other investigations concerning control of structural dynamics – both presumably in support of the US Supersonic Transport (SST) effort.  It made numerous high-speed instrumented flights in support of these efforts.

Retirement and Disposition

AV-1 was retired in 1969.  Its last flight – a subsonic one – was on 4 February 1969.  It was flown to Wright Field, Wright-Patterson AFB, OH, and was transferred to the Air Force Museum (now called the National Museum of the US Air Force).

For years the surviving XB-70 (AV-1, tail number 20001) was on display outside at the Air Force Museum, and was one of the first things a visitor saw while approaching the museum on foot.  I can tell you from personal experience that made one helluva impression.

AV-1 is still at the museum today.  However, it’s now been moved to the museum’s R&D hangar and is protected from the elements.

As I alluded to above, I’ve seen this airframe too – over 30 years ago.  It was amazing then, and still is.  IMO, it’s perhaps the only aircraft I can think of that can come close to the A-12/SR-71 family in terms of either performance or physical beauty.  On the latter score, I’d be hard pressed to pick between the two.

I never got to see either take off, or in flight.  I certainly wish I had.

Seeing a takeoff for either would truly have been something to remember.

 

Sources:

There are a variety of sites and articles about the XB-70 freely available on the Internet.

Wikipedia’s article on the XB-70 appears reasonably accurate and gives an excellent overview of the aircraft’s background, mission issues, a brief programmatic history, and the events leading to its cancellation.

The site http://xb70.interceptor.com/ provides an absolutely excellent history of the aircraft, focusing more on its flight test operations and technology.  It’s definitely worth a read.  It also has an excellent photo gallery with photos of the XB-70 and other aircraft.

Various other sites have images or other information about the craft.  Some of the images of the XB-70 I find worth looking at are found at the following links:

http://www.scenicreflections.com/files/North%20American%20XB-70%20Valkyrie%20Wallpaper__yvt2.jpg

http://www.murdoconline.net/2008/xb-70_rear.jpg

http://upload.wikimedia.org/wikipedia/commons/7/7c/North_American_XB-70_in_Flight_EC68-2131.jpg

http://en.wikipedia.org/wiki/File:North_American_XB-70A_Valkyrie_in_flight_061122-F-1234P-022.jpg

http://upload.wikimedia.org/wikipedia/commons/9/9f/North_American_XB-70A_Valkyrie_in_flight_with_wingtips_in_25_percent_%28transitional%29_drooped_position_061122-F-1234P-020.jpg

http://upload.wikimedia.org/wikipedia/commons/7/76/North_American_XB-70A_Valkyrie_in_flight_061122-F-1234P-022.jpg

http://www.flygplan.info/images/XB-70_800.jpg

http://pl.yoyowall.com/wp-content/uploads/2013/08/Air-Force-XB70-Valkyrie.jpeg

http://www.thexhunters.com/xpeditions/xb-70a_aircraft_3.jpg – This photo is noteworthy in that is shows both the XB-70 and the B-58 (used as a chase-plane for some XB-70 flights) together, and gives an idea of the relative size of the XB-70.  The B-58 was nearly 100 feet long (96ft 10in).

http://i6.photobucket.com/albums/y217/dirksterg30/Aircraft/B-70.jpg

http://api.ning.com/files/HfUvPSttO0Jx7wxzeEqxNDa5gR0YRJHqJFHoJkFRTZjkUkJSFfOukfc6QLlfPTrBoh1Vdm0GJJtDuQfdtoqFCf0YMmK2ZWwo/XB70Valkyrie1.jpg – This photo shows the XB-70 on the ground, surrounded by people, at the North American Aviation plant (I think this was taken at the plane’s public “roll-out”).  It also conveys the huge size of this aircraft.  Its wingspan – 105 feet  with wingtips horizontal – was longer than the B-58’s length.  It was 189 feet long.  Max takeoff weight was 542,000 lbs (271 TONS).

http://photos.interceptor.com/main.php?g2_view=core.DownloadItem&g2_itemId=9318&g2_serialNumber=1

 

The bird was indeed a beautiful one.

Category: Air Force, Historical