The idea of the Valkyrie

XB-70 Valkyrie high in the sky

This one of a kind aircraft - the North American XB-70 Valkyrie - was an American made bomber aircraft which a logic similar to the SR-71's. Since there were not very good SAMs in the 1950s, the only (almost) threat to enemy aircraft was interceptors. Therefore an airplane that could fly faster and higher than these interceptors was practically out of the “danger” zone. But there was also another strategic meaning of the stunning speed. That was that if it was to deliver nuclear bombs then it would have to be able to get away fast enough not to get damaged by the explosion.

The design of the XB-70

XB-70 using parachutes to stop after a flight

• Valkyrie had to be big to carry a lot of bomb load
• A big fuel capacity for the long flight (no refuelling was possible once it got too close to USSR Territory)
• Completely new engines that could fly at a sustained speed of Mach 3.0 had to be developed.

They chose the long thin delta design - the preferred body design for supersonic flight at the time. After years of wind tunnel testing and engine developing the engineers finally had a structure and engines that would be able to fly at supersonic speeds for a long duration, instead of having to switch between sub- and supersonic speeds. However, when the developers finally thought that they had the best design, they found out that to get an even more increased lift and therefore increased range. How? They could take advantage of a newly discovered phenomena called compression lift. This means basically that the aircraft rides on the shockwave of higher density air that it produces itself at the tip of the front, providing additional lift. This made them have to re-design parts of the aircraft before actually producing the full-scale aircraft. The XB-70 Valkyrie was one of the first aircraft to ever use the compression lift feature.

Extreme features of an extreme aircraft

The enormous size and the six engines of the XB-70 Valkyrie

The Valkyrie was one of the most extreme aircraft at the time. For instance, its speed was almost as high as the one of the SR-71 Blackbird. It was capable of delivering nuclear bombs. And it had no less than six(!) General Electric engines. Some other features of the XB-70 are listed below:

The cooling of the XB-70

The speed that the engines resulted in made the aircraft heat up - A lot. Both the air-compression in front of the aircraft and from the burning of fuel. In some areas of the aircraft could reach temperatures as high as 330° Celsius. That was a major problem that had to be solved. It was fixed by using a sandwich material consisting of stainless steel and foil. Titanium was, just like on the SR-71, used due to its extreme durability, but to a much smaller extent. To fix the heating-problem from the engines, the fuel was circulating inside the aircraft before entering the engines - a principle similar to the one in water-cooled computers.

The down of the Valkyrie

The previously mentioned fact that there was almost no anti aircraft missile capable of shooting down aircraft at altitudes of over 15000 meters at this time (since the aircraft flew out of range of the SAM so quickly) was, however, changing during the late 1950s. During these years the Soviets developed much better and cheaper anti-air systems capable of flying even higher than the XB-70. This is what has been named the “missile-problem” for the Valkyrie. Along with the fact that ICBMs took over the role of long-range nuclear bombers (an Intercontinental Ballistic Missiles is in a way a “long-range-bomber”) - the two main advantages of the XB-70 vanished. The US Air Force shifted their effort towards low-level bombers. Therefore the cancelling of the XB-70 program was inevitable.

The project cost of $1.5 billion of the XB-70 only resulted in two finished prototypes. One of them collided with a jet aircraft in mid-air ending in a fatal crash and the other can be seen at the National Museum of the United States Air Force in Ohio. Even though the XB-70 can be called a failure, it was an important research aircraft for NASA and is definitely an aircraft of its own class. The word “Valkyrie” comes from Scandinavian mythology, meaning "One of a host of female figures who choose those who may die in battle and those who may live".  With the XB-70’s six engines, nuclear-bombing capability and Mach 3.1 speed, that is the right name - for an excellent and very beautiful aircraft.

Crazy story of an Emergency Landing

• Read about Russia's new Mach 4.0 interceptor here.
• Read about the SR-71 here.
• Interested in naval warfare? Read the three-part series about the Nimitz class aircraft carrier! The first article can be found here.

• Xb70.interceptor
• Nationalmuseum.af.mil
• Jenkins and Landis 2002
• Af.mil

The post Mach 3 Bomber Valkyrie appeared first on Afterburner - MiGFlug's Magazine.

The successor of the Blackbird

The Lockheed Martin SR-71 Blackbird

It will succeed the SR-71, serving the same primary purposes: surveillance and intelligence gathering. Other areas of use will be to cover the gap that currently is between surveillance satellites and subsonic manned aircraft within the USAF. The defining feature of the unmanned SR-72, just as with the SR-71, is pure speed. With its assumably Mach 6.0 capability, it will be able to penetrate enemy airspace, drop a bomb (for this it will have to be equipped with special equipment) or monitor before the enemy has time to intercept it. The SR-72 will be a brand new type of aircraft. Since its speed is so tremendously high, being spotted by the enemy will not matter (Only SR-71 has had this as its main feature before). This is what Lockheed Martin wants to accomplish.

Scramjet - The engine of tomorrow

The engine of it is one step up from the Blackbird’s. The engines needed to reach speeds of Mach 2.2 are called turbojets. The engines that will be used to reach the top speed of the SR-72 are called scramjet engines (although they can hypothetically reach speeds of over mach 15). Because of the fact that a scramjet does not work at speeds of lower than mach 1, the aircraft will feature a turbojet as well to accelerate it to the speed to where the scramjet can take over. The scramjet is still conceptual and there has not been any actual aircraft using one (expect the X-51, see further down), this is why Lockheed is collaborating with Aerojet Rocketdyne and Boeing to make the new engine, together currently leading the development of a scramjet. How the engine of the SR-72 will work however is currently not known to the public - and it is an extremely complex piece of machinery featuring both a scramjet and a turbojet. The project might however have a rough time ahead as Lockheed Martin had, by the time of the concept unveiling, not yet secured the fundings needed to build this kind of scramjet, the complexity and therefore the pricetag being two possible reasons.

Cheaper solution to the problem

Northrop Grumman RQ-180 in flight

Another reasons for them not receiving funds might be that they have competitors, one of them being the classified Northrop Grumman RQ-180 which is also a surveillance UAV being funded by the United States secret military budget. Northrop has skipped the whole speed part and instead concentrating on a stealthy drone to do the ISR (Intelligence, surveillance, reconnaissance). This project has gotten more positive feedback both because of less risky technology will be used (compared to the SR-72 which will have to develop an entirely new kind of engine) and that it can be put into service already by 2015.

Going hypersonic in the near future

The Boeing X-51 under a B-52

The scramjet engines will be tested in Boeing’s X-51 project which is an unmanned, single engine aircraft. It is projected to be, in the near future, flying at mach 6.0. The aircraft is actually the record holder of “The world’s longest scramjet flight at hypersonic speeds” title after it held a speed of over mach 5.0 for 210 seconds in may 2013. It has gotten a nickname, the WaveRider, because of it using its own shockwaves to add extra lift. The aircraft did not have a turbojet installed so to get to the supersonic speeds needed to use the scramjet it was carried 15km into the air by a B-52 bomber, then released and falling untill reaching proper scramjet speeds. The SR-72 will probably not be the first aircraft to use the engine when it is done, as missiles are proposed to use it as soon as in the 2020s.

SR-72 - 2x the speed of the fastest

Conceptual deisgn of the SR-72

But if Lockheed Martin manages to make a hypersonic engine and propell an aircraft to a speed of mach 6.0 it will be an achievement about as big as the SR-71 back then. With more than twice the speed of any other air breathing aircraft ever built, it will earn its place in the history books. These kinds of engines might lead into an entirely new age of aircraft with Lockheed Martin at the very edge. Lockheed Martin has a long way to go and a lot of obstacles to pass, but if anyone should take on this risky but rewarding mission it is them, with tons of successful, first seeming impossible creations, such as the SR-71, F-117 and F-22. But at the current stage all we can do is to watch while the experiments continue and maybe, just maybe, we will one day see the SR-72 with its brand new engines astonish us all, just like the Blackbird once did.

Additional reading:

• Read about Russia's new mach 4.0 interceptor here.
• Read more about the SR-71 here.
• Read about the trillion dollar project here.

Sources:

• Extremetech.com
• Lockheedmartin.com
• Aviationweek.com
• Wired.com
• Rusi.org

The post The SR-72 – a new Blackbird? appeared first on Afterburner - MiGFlug's Magazine.

The Russian military aircraft design bureau Mikoyan Gurevich has since the 1940’s been building many famous military aircraft, some of which were exceptionally fast. Two of these are the MiG-25 and the MiG-31, capable of speeds exceeding Mach 3.2 and Mach 2.83 respectively. MiGFlug offered both for flights in the past, read more here. Now there have been rumors that MiG is trying to do it again - building a superfast interceptor. The project is currently designated MiG-41, with projected speeds exceeding Mach 4.0. According to the famous Russian experimental pilot Anatoliy Kvochur, the MiG-41 is to be capable of reaching speeds up to Mach 4.3 (about 5270km/h or 3270mph).

MiG-25 Foxbat - The legend

Picture of a MiG-25 from behind showing the engines that got it to Mach 3.2.

To trace the history, we must go back to 1964 and the introduction of the MiG-25 Foxbat. Built to intercept missiles and high-speed American aircraft (such as the SR-71) it had a speed which was almost as high as the Blackbirds and a service ceiling of 20,700 meters. A big advantage it had over the SR-71 was that it was not only a surveillance aircraft, but it also carried four air-to-air missiles as well which made it a deadly weapon. Unlike the Blackbird which was only built in a few copies, the success of the MiG-25 made it having over 1,100 units built! To say the least, this was a success, and only 17 years later the next step in the Mikoyan series had its introduction.

Foxhound - the successor of the MiG-25

Mikoyan Gurevich-31 "Foxhound".

The MiG-31, NATO reporting name Foxhound, was its name. It had a top speed of 2.83 Mach and a service ceiling almost as high as the MiG-25. It was built to intercept and take out targets at any altitude within its service ceiling and it is effective at any weather condition, day or night. It is also built to be effective against passive and active electronic countermeasures and against heat flares. The big improvement over its predecessor is its weapons arsenal. The Mig-31 can be equipped with a very big arsenal of weapons and guns, which are listed below:

As can be seen, the weapons arsenal of the Foxhound is a big step up from the Foxbat who only featured these weapons:

The MiG-31 has many other advantages as well; some smaller, some bigger, such as the second seat which is dedicated to a weapon officer having control of the weapons. In the MiG-25, the pilot was in charge of the weapons as well as the flying. The MiG-31 was capable of supersonic speed at low altitudes, something that the MiG-25 was not, this the Foxhound has its upgraded and stronger airframe to thank for. Some other improvements are the wing loading, ferry range, and the thrust/weight area which is more than double the one of the MiG-25 (0.85 vs 0.41).

MiG-41 - what will it be about?

So now to the point of this article, the MiG-41. There is not very much known because it is, just like all top modern military projects, very secret. But we do know that there is a program going on as the deputy Alexander Tarnaev at the Russian State Duma Defense Committee said this during an interview at the Cultural Center of the Russian Armed Forces:  “The corresponding decision was taken by the Chief of the General Staff; he has already signed the document to carry out research work on the MiG-41 project”. We also know that the new MiG will be based off of the Foxhound as Tarnaev also said this about the project: “Will embody all the advantages of the MiG-31 fighter-interceptor jet”. To do this they will need testing platforms, which might be why hundreds of MiG-31s will be overhauled and put into service with the Russian Air Force.

What we will see when the MiG-41 will be introduced is still unknown as the project is rather new and not very much has been leaked. Howeve,r when looking at how the MiG-31 developed from the Foxbat and thinking about the MiG-41’s mach 4.0 (even 4.3) capability we can say that it will probably be a heavily armed interceptor with high service ceiling and - obviously - a very high speed.

If you are interested in additional reading:

• Did you know that it is possible to fly in a MiG-29 fighter jet to the Edge of Space, as a Civilian? Read more.
• Read about the American SR-71, the world's fastest aircraft here!
• Read about another Russian project from the 30's: The Kalinin K-7 bomber here.

Sources:

• Theaviationist.com
• Globalaviationreport.com
• Militaryphotos.net
• ruaviation.com

The post MiG-41 – A new Mach 4+ fighter? appeared first on Afterburner - MiGFlug's Magazine.

To start with - there is a nice video of (former) Top Gear's Jeremy Clarkson explaining the fastest plane in the world - Lockheed SR-71 Blackbird.

Airplanes. They come in many different shapes and sizes, materials and colours. Some are built for surveillance, some for vertical takeoff, and others for transporting heavy cargo across the globe. In this article series, we will look into three different categories of airplanes. This part will be about the fastest aircraft ever flown, the second part will be about the oddest looking ones, and the third part will be about the largest airplanes that have ever been able to lift. In this article, we will look into one of the very few airplanes that have flown faster than Mach 3.0 (~3,675km/h).

SR-71 Blackbird

The aircraft we will examine is the American Lockheed SR-71 Blackbird, built by the famous Lockheed Skunk Works division. Now, let us not bark around the tree, what is this aircraft really about? It is as of today the world’s fastest manned air-breathing jet ever flown with an official top speed of Mach 3.3, although some claim that it is higher and since some parts of the Blackbird project are still classified - so we can’t know for sure.

“It is a race this jet will not let us lose. The Mach eases to 3.5 as we crest 80,000 feet. We are a bullet now - except faster” - Major Brian Shul, Author of “Sled Driver”.

The SR-71 temperature problem

Retired SR-71 pilot Lt. Col. Ed Feilding illustrates that the plane's top speed really was "faster than a speeding bullet."

Because of the astonishingly high speed, the aircraft was travelling at, the canopy was heated up to over 300°C. This meant that its design had to be completely rethought about. The high temperatures are a result of a physical phenomenon that is causing the air molecules at high speeds to be smashed into each other which results in higher pressure which leads to higher temperatures. In easy words: The air molecules can’t get out of the way fast enough so they pile up in front of the jet and give off heat. This meant that the airplane had to be built so that it could both withstand high temperatures, high stress, and be stealthy. Because yes, the Blackbird was using stealth technology. It was actually the first operational aircraft using stealth features. Of course, it did not have a low radar cross section as modern fighters have, the SR-71 had an RCS of about 10m^2 while for instance the F-22 Raptor looks like a marble on the radar. The solution to these three problems was a worked alloy of titanium covered with a corrugated skin, crafted into a stealthy shape. The titanium was used because of its extreme durability, while the corrugated skin was used to deal with the above-presented heat problem because the normal paint would just be curled and split by the high temperatures. Stealth was a brand new idea, and the use of 85% of titanium in the structure was also an almost unexplored area of engineering. When welding the titanium normal tap water could not be used as it was corrosive to the titanium, the same went with the “usually” used cadmium plated tools that

Temperatures of the SR-71 during flight (550°F ~290°C).

also caused corrosion, requiring entirely new tools to be procured. There were also problems with metallurgical contamination at one point during Blackbird production, over 80% of delivered titanium had to be discarded. Interesting note here: The primary alloy for the SR-71, titanium, was so scarce outside the USSR that the CIA had to import some covertly from the Soviet Union. One might assume this aircraft was at its structural limits at Mach 3, but in fact, it performs best at this speed. As a matter of fact, it was built to fly at this speed. At very high speeds of Mach 3+, the SR-71 flight body heats up so much that the metal expands a lot. If the metal pieces of the airplane at this point would have been tightly screwed together, the aircraft would simply expand to its own death, making the expansion push the metal pieces into each other with very serious consequences. This is why the Lockheed Skunk Works division built the Blackbird with big gaps at some points in the structure, resulting in the body dripping fuel, as is explained by the quote below:

“Ironically, the plane was dripping, [...] Fuel was seeping through the joints, raining down on the hangar floor. At Mach 3, the plane would expand several inches because of the severe temperature, which could heat the leading edge of the wing to 1,100 degrees. To prevent cracking, expansion joints had been built into the plane. Sealant resembling rubber glue covered the seams, but when the plane was subsonic, fuel would leak through the joints.” - Major Brian Shul, Author of “Sled Driver”.

https://youtu.be/mHjhgeyhuKk

The engines that got the SR-71 to Mach 3

Pratt & Whitney J58 engine with full afterburner engaged.

But what does the SR-71 actually own its speed to? Its engines. The two black "pods" on each side of the flight body are as complex and thought through as the rest of the aircraft. They consist of two Pratt & Whitney J58 engines which were at the time the only American engines built to continuously use afterburners (which is why the SR-71 consumed so much fuel). Just like previously mentioned with the flight body being built for extreme speeds - so were the engines with their ultimate cruising speed at Mach 3.2. When going supersonic, the air going into the engine is travelling at supersonic speeds, resulting in shockwaves inside of the engine which might lead to engine failure. To get rid of this problem, the inlets to the engines on the SR-71 are "blocked" by a big pointy piece of metal, called a spike, which moves forward and backwards depending on how fast the aircraft is flying. When flying at top speed, the spikes could retract as much as 66 centimetres into the engine, changing the speed of the incoming air to a subsonic 0.5 Mach. It does this to keep the air pressure inside of the engine constant. The same idea is used on among others by the Soviet Sukhoi Su-22 Fitter. However, sometimes when going supersonic, the engines failed in changing the pressure of the incoming air which led to only one of the engines going supersonic. The result of this is heavy jawing which can only be solved by restarting the engine, however often both of the engines were restarted to be sure that the yawing stopped. The energy of the shockwaves at the spike, plus the heat produced by the constantly used afterburners, heated up the compressors to temperatures of over 400°C. Actually, the maximum temperature the engine compressors could work at (427° Celsius) was what limited the speed of the Blackbird. However, studies made in the later years of the 20'th century showed that with the right materials, engine inlets of the SR-71 type could theoreticaly work at speeds as high as mach 6.

The speed was its main defence

But even though the Blackbird was so expensive and hard to build, it did get onto the production line, and it was an enormous success. Not only was it black, had been a secret project and looking like it was from another planet, it was the fastest aircraft the world has ever seen. And more importantly for the US - it was faster than anything the Soviets had ever built. Although it carried electronic countermeasures, the main defensive system of it versus missiles was simply to outrun them, just like quoted from the SR-71 Blackbird documentary on PBS:

“If a surface-to-air missile launch was detected, the standard evasive action was simply to accelerate and outfly the missile”.

The effectiveness of this defence was proved in 1981 when Kelly Johnson, one of the designers of the Blackbird, announced that over 1,000 missiles had been launched towards the SR-71, but none of them had hit. Out of the 32 SR-71s that were built, 12 were lost due to accidents, never because of enemy fire. While talking about weapons and countermeasures, it is needed to say that the SR-71 was never fitted with any weapons. Of course, this was due to many reasons but one was that it was simply not built to shoot. It was built to surveil and take pictures and since it could not (in practical) be shot down it had no need to be fitted with weapons. The Blackbird was only capable to fly for approximately 5,400km which may seem like a lot, but compared to the Lockheed U-2, another reconnassaince aircraft, with a range of over 10,000km, it is (very) inferior. The short range, which was a result of the very thirsty engines, was the reason for the in-air-refueling capability to be fitted with the SR-71.

To the edge of space in a titanium bird

Spacesuit used by the crew of the SR-71.

It flew so high and so fast that the crew needed pressurized space suits when flying it. And it is said that at the maximum altitude of it it was possible to see the curvature of the earth, which refers to this quote by Colonel Alison: “On a clear day you can see forever…”. The service ceiling of 85,000 feet (25,900m) meant that it was an excellent experimental unit for space travels. That, combined with the great speeds of it was two of the reasons why NASA decided to take over the last two Blackbirds after its retirement from the Air Force in 1998. This means that the world’s fastest aircraft was in service from 1966 until NASA retired its two units in 1999, and most of the remaining Blackbirds are today stationed at museums or military bases across the US.

Since the dawn of these airplanes there have been countless missiles and other rocket-propelled aerial vehicles moving faster than Mach 3.3 but there has never been a manned, air-breathing one. We do not know if there will be one in the future - and given the recent developments with UAVs it looks unlikely - but we do know that when the Blackbird entered service with the US Air Force, it was cooler, faster and more astonishing than the world had ever seen before. Gathering information about the enemy while flying at an altitude of 20,000 meters at speeds as high as three times the speed of sound is a true proof of the skill of American Skunk Works engineers. Just being able to accelerate away from a surface-to-air missile and use that feature as a main defence is a huge accomplishment on its own. The Lockheed SR-71 Blackbird will therefore reserve a special place in most aviation lover’s heart.

Additional reading:

• Which fighter is the best – The F-22 Raptor vs The Eurofighter Typhoon
• Read about the trillion dollar project: 5th generation fighter jets too expensive?
• Read about a giant bomber project: The giant bomber of the 30's - Kalinin K-7.

Sources:

• CIA
• Army.mil
• Aerospaceweb.org
• Wvi.com
• Gizmodo.com

The post The fastest Plane in the World – SR-71 Blackbird appeared first on Afterburner - MiGFlug's Magazine.