XB-70 Valkyrie - The Worlds Fastest Bomber

"That's not a plane it's a three plane formation" that's what General Curtis LeMay said over plans of the WS-110 supersonic replacement for the B-52 back in 1954. Back in the early 1950s the B-52 was the US Air Force's main nuclear delivery platform but with the increasing sophistication of the Soviet defenses, a new supersonic bomber was called for that would stretch the limits of technology to beyond what was thought possible just a few years earlier. The plane that would emerge from the WS-110 design process was the XB-70 Valkyrie. It will be one of the biggest in the world and capable of cruising at Mach 3 something which no aircraft of this type is capable of doing even now. It would also fly at 77,000 feet 23,500 meters have a range of 4280 miles or 6900 kilometers and carry up to 14 nuclear weapons. The problem with large planes and payloads is the need for powerful engines which in turn require a lot of fuel which has to be carried making the plane heavier and reducing the available payload. So in the 1940s and 50s alternative methods of propulsion were researched. Nuclear was seriously considered as a power source for jet engines. A nuclear reactor would heat the air in place for jet fuel and it could run for weeks or months without the need for refueling but problems with the extra weight of a radiation shielding required for the crew and the low thrust output from early engine designs meant that it became unpractical. Also if a nuclear powered plane crashed it would be a much bigger problem than a conventional jet due to a radioactive contamination. If you want to find out more about nuclear power planes trains and automobiles we have a video on the link showing now. Also during the 1950's a new type of jet fuel was being developed called high energy fuel or "Zip Fuel" this could deliver up to 40% more energy for the same weight. This was achieved by adding boron a high-energy low mass element. The problem with this is that it made both the fuel and the exhaust toxic. When zip fuel was burned in engines it produced solids that were sticky, corrosive and highly abrasive this also created a lot of black smoke which could reveal the plane's position even at high altitude. These solids built up on the turbine blades making them less efficient and in some cases causing the engines to fail completely. One method to get around these issues was to use it in the afterburners as this didn't affect the engine itself. This would be used for a quick dash up to supersonic speeds over enemy territory whilst using normal jet fuel for the rest of the journey. Due to the high cost of making zip fuel and the inability to overcome the engine damage it caused meant that it went the same way as of nuclear power engines and by 1959 zip fuels were also dropped. Both nuclear engines and zip fuels were proposed for the WS-110 before new higher density type of conventional jet fuel called JP-6 was developed. To overcome the extra fuel needed, the North American Aviation's WS-110 design had floating wing panels at the end of the wings which were essentially huge fuel tanks these would have been jettisoned when it went supersonic leaving much shorter of trapezoid shape wings. LeMay head of the US Air Force Strategic Air Command thought that this was too complicated and dismissed the idea and in 1956 the US Air Force told the designers to go back to the drawing board and come back with a better design. Research on supersonic flight was progressing rapidly and narrow delta-shaped wings took the place of a swept back or trapezoid ones of the original WS-110 design along with newer engines that could cruise at supersonic speeds. During the engine research a discovery was made but if the engines were optimized for supersonic speeds it burnt twice as much fuel as it did a subsonic speed but flew four times as fast, meaning the most economical speed was now the maximum speed. It was now easier and more economical to cruise for most of the entire flight at Mach 3 than it was to fly slower to the target and then fly over the enemy positions supersonically as the old ws 1:10 design was intended. North American also discovered some obscure Windtunnel research into a phenomenon now known as "compression lift" which used the high pressure shock wave created at the front of a plane at supersonic speeds. By designing a combination of the wing position relative to the nose large wing tips that could be tilted down to contain the high pressure air and a specially shaped engine intake of the six centrally placed engines the plane could ride on the shock wave created by flying supersonically and thus reduce the amount of fuel required. The new design was approved and given the designation B-70 with the prototypes getting the "X" for experimental aircraft so they became the XB-70. The name Valkyrie was chosen as the winning entry in the US Air Force "name the b70" contest. It was also around this time in the late 1950s that Soviet surface-to-air missile technology became much more effective. This removed the high-speed high-altitude advantage that the new B-70 design would have and flying it at low altitude under the radar it was not much faster than the B-52 it was made to replace but with a smaller payload and shorter range. This combined with the cost cutting as intercontinental ballistic missiles or ICBMs, became a cheaper unstoppable way to deliver nuclear weapons meant that by 1961 when Kennedy was in office the program was scaled back and the bomber concept was dropped. Instead it would become the XB-70 research plane to study supersonic aerodynamics and propulsion in large aircraft with first three, then two prototypes being built. However because of its cutting-edge design things were not so straightforward once the build got underway. Although the XB-70 was considered for reconnaissance as the RS-70 the other Mach 3 aircraft in development at a time the lockheed A-12 which would become the SR-71 blackbird was superior in terms of altitude it could fly at, the maximum speed and had a much lower radar cross-section so it would be much harder to detect. Unlike the SR-71 the B-70s were designed to be a large fleet of aircraft but there wasn't enough to titanium that could withstand the heat generated at Mach 3 available for that many aircraft. This led the US Air Force earlier on in the design process to request the body of the aircraft we built out of cheaper more readily available materials. So a special combination of a stainless steel honeycomb skin was used over areas where the heat was going to be less of an issue up to 450 degrees Fahrenheit 232 degrees Celsius. The forward 60 feet or 20 meters of the plane would use titanium where the temperatures would reach up to 650 degrees Fahrenheit 343 degrees Celsius and the engine compartment used a nickel based alloy called Rene 41 which would withstand 1,200 degrees Fahrenheit or 650 degrees Celsius. But this mixture of different metals caused an unforeseen issue of electrolytic corrosion and led to a two-year delay as the plane was stripped and rebuilt. The design also called for pressurized fuel tanks but when they tested them with normal jet fuel they'll leaked.. a lot. This was down to tiny flaws in the welding as the tanks were fabricated. It took a further 18 months to find a fix by lining the inside with a special coating. Finally on the 21st of September 1964, the maiden flight of the first xb-70 took place but even that didn't go to plan. One of the six engines had to be shut down and there was a malfunction on the undercarriage, this led to the brakes locking up on one side when it landed which burst the tires and set fire to the undercarriage. On the following tests after the XB-70 was taken supersonic the flexing of the airframe which it was supposed to do, caused much of a thick white paint to flake off and on two occasions large pieces of the wings leading edge was ripped off as a stainless steel honeycomb skin failed due to poor quality control. But the most serious incident wasn't caused by anything failing on the XB-70. On the 8th of June 1966, after a successful supersonic test flights XB-70 number two was returning with four chase planes in a tight formation and being filmed for GE who made the engines for all the planes. The filming had just finished as a Starfighter F-104 was flying about 70 feet or 20 meters from the right wing tip. It's believed that the pilot couldn't see the wingtip to his immediate left and above and that he was using the forward part of the XB-70 as his visual reference point. For some reason he drifted a little too close and touched the right wing. The vortex from the large wing tip of the XB-70 sucked the small fighter up and over the tail of the XB-70 hitting both vertical fins before it exploded and crashing into the left wing tip which then broke away. Without its rudders and the wing damage the XB-70 entered an uncontrollable flat spin and crashed to the ground. The pilot Al White ejected and survived but was seriously injured. The XB-70 co-pilot Carl Cross was unable to eject and went down with the plane. The F-104 pilot and NASA chief test pilot and one time X-15 pilot, Joe Walker also died as a result of a collision. The remaining XB-70 continued its research until 1969 when it was retired to the National Museum of United States Air Force at wright-patterson Air Force Base where it has been ever since and the XB-70 valkyrie became part of supersite history. And as always thanks for watching and please subscribe, rate and share.

Channel: Curious Droid

Views: 2,135,890

Keywords: xb-70, XB-70 Valkyrie, mach 3 bomber, supersonic plane, worlds fastest bomber, nasa x plane, nasa xb-70, x planes, b-52, ws-110, curtis lemay, nuclear powered plane, zip fuel, high energy fuel, sr-71, blackbird, Strategic Air Command, compression lift, b-70, rene 41, Al White, Carl Cross, Joe Walker, bomber, valkyrie, curious-droid.com, nasa, united states air force, aircraft, airforce, missile, supersonic speed, uasf, x-15, xb70, North American Aviation, paul shillito

Id: oHqNNOiooLQ

Length: 10min 36sec (636 seconds)

Published: Sat Apr 29 2017

Reddit Comments

[u/dog_in_the_vent]

Great video! I didn't know about the paint flaking off like that.

[u/myockey]

Interesting to see this posted today. I paid it a visit just this afternoon at the National Museum of the USAF.

[u/Rule_32]

This is one of my all time favorite aircraft, such an extreme machine!