The SR-91 “Aurora”: The Plane that Doesn’t Exist…

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Not sure if it's true or not, but when Kelly Johnson (SR-71 designer) died in 1990, people said he told them we would be blown away by the stuff we were working on, back in 1990.

The fact that the SR-71 flew for years in secret makes me believe this SR-91 exists in some shape or form

I’m sure it exists, I grew up near Edward’s Airforce Base and lived in neighborhoods with all kinds of people who worked at Skunkworks and it was kind of an open secret. We would hear the sonic booms all the time and joke “there goes the plane that doesn’t exist. Did you hear anything? I didn’t hear anything.”

The fact that Lockheed was so excited about the SR-72 becoming technically feasible in the early 2000’s makes me think the SR-91 was either a technology demonstrator or something similar.

So, the one piece of evidence that I consider most telling is the KC-135Q tanker aircraft. They were dedicated to carrying JP-7 fuel for the SR-71. When they retired the SR-71, they did not retire the KC-135Q tankers. So, there was still something flying at that time which used JP-7. We don't know what it was, but that fuel is so hard to ignite and contains so much energy when it does ignite, that there's really only one use for it -- high supersonic or ultrasonic flight by aircraft like the SR-71. That's all I've got.

I knew a retired SR71 pilot in the 1990's (now deceased) and he would not give up any information about the Blackbird except what was already known. He did mention that the U.S. government was working on a replacement for decades while the Blackbird was still flying and they are always researching the "next aircraft" to replace the newest ones. eg: when the F22 first went into production, they were already drawing up it's replacement. They think of future generations of aircraft while they are still developing current ones. The 1 thing he did tell me was that ramjet and scramjet technologies are no secret and have been in development for a very long time as well as pulse detonation to conserve fuel once you reach the momentum of hypersonic flight at altitude. I assume he probably meant well over 100,000 feet where the atmosphere is much thinner. You are correct that a spy plane will always be in the U.S. inventory because they can be used in a pinch and being at a lower altitude than a satellite, their photos are a much higher resolution.

For the Aurora to NOT exist, it means that aeronatical engineers must have sat on their hands for the past 50+ years...

I was an en route air traffic controller in the southwestern US from 1980 on. I worked the F-117 aircraft in early testing and later training missions for deployment in the Middle East. I worked SR-71s weekly. U-2 aircraft as well. Our radar equipment and associated automated beacon interpreters were capable of accurately determining the speed of beacon tracked aircraft under positive control. I can say the top speed of of SR-71 aircraft I worked was greater than any published speed today. On one shift I noticed an strange untracked primary radar signal (actual radar skin reflection vs. beacon interrogator system typically used by all aircraft including the military. It caught my eye on the radar scope as it had quickly transited the airspace I was controlling, at roughly 2-4x the speed of the SR-71. I thought it was probably an equipment anomaly but noted the course of the target would place it over northern Arizona just south of the Mojave military aircraft testing area the F-117s operated out of with the track projected to continue east near Albuquerque and on to Amarillo, Texas. On break shortly afterwards I was outside the facility when I noticed a strange west-east contrail that had puffy blobs at regular intervals. This was the expected “soap on a rope” contrail of a scramjet engine. I have no doubt what I saw on radar and later, the associated contrail, was a hypersonic test aircraft using scramjet propulsion. Either the aircraft was only a test bed and never fully developed for deployment, or it has been highly successful and remains classified. Probably the former. So many stories about working he F117 before it was declassified and the problems it created for air traffic control due to very unusually performance characteristics as well. And yes, in the USA, all aircraft operating above 18,000msl are under civilian air traffic control.

In the late 1980s I was a USAF officer assisting the Saudi Air Force with the development and fielding of a state-of-the-art air defense system for the Kingdom of Saudi Arabia. It was called PEACE SHIELD. The lead contractor was Boeing, and Hughes was a primary subcontractor. The program was so massive and technologically advanced that we had quite a few contractors (beltway bandits) acting as advisors to support us. Most of them were former or retired Air Force radar operators and air combat controllers. As was the custom on our many trips to Seattle to visit the Boeing facility in Kent, I was sitting in a hotel bar one evening with five of these former scope dopes I had gotten to know rather well. As the drinks flowed, each one tried to top the last one's story of Soviet bomber intercepts, remote deployments, and so forth. Eventually the topic of Aurora came up. Each man had his opinion regarding whether or not it was real, but one guy in particular told a strange and convincing story. He was manning his air defense console and tracking the usual air traffic. Each aircraft was represented on his screen as short smear lines. The longer the line, the greater the relative speed of the plane. Suddenly a track appeared out of nowhere and it was far longer than any he had ever seen, including the vaunted SR-71. He immediately reported it and waited for confirmation and further instructions. When the reply came back, it was an order to ignore the track. He was told nothing more and never learned anything beyond what he said to us, but he believed it might have been the mysterious Aurora.

I like to think that Aurora really existed (perhaps still exists, hidden away in an underground facility somewhere in the deserts of California or Nevada), and that Clarence "Kelly" Johnson played a part in its early stages of development. If there was anyone who could have made Aurora happen, it was Kelly Johnson, who led the teams that developed the P-80, U-2, F-104, and SR-71. It would have been the perfect final chapter in an illustrious career.

My theory is that "the Aurora Project" was a program that had several craft come out of it, the TR-3B being the most advanced. Tangentially related: my freshman science teacher ('92) told us to keep our ears out for something called the Aurora Project in about 20 years (from then). That's all he said about it.

According to a senior Air Force officer, AURORA is not a plane. Aurora is a PROGRAM and a series of craft. In the early 2000's on Sunday mornings I would see contrails looking like a knotted rope, presumably originating from Edwards or Vandenberg AFB

I absolutely saw the phenomenon one night while taking a walk on a friend’s ranch near Gorman California. The skies there were free from light pollution and we were already at 5k feet elevation. It was common to take nightly walks and this night I was alone. I was walking North and on my left I noticed a quickly growing trail with what looked like puff balls preceded by a flashing pulse of orange-ish light. It was moving from S to N and I reckon it was very high and must have been flying over the Pacific. Directly West of my location was Ventura, and to the East was the Mojave Desert where Edward’s AFB and the Skunkworks facility in Palmdale. I told my friend when I got back to the ranch house but no one believed me and by that time there was no evidence. I was in HS and still fairly young. Was probably 1994/95. I know what I saw and even though to this day no one believes me, I am convinced it was an experimental aircraft and I’ve never seen anything like it since. Honestly, it was pretty freaking awesome.

If I remember correctly, the USAF retired the SR-71 (rather abruptly) right around the time the Aurora was supposed to have been developed. Then, a few years later, they put it back into service. Connecting those dots suggests that the Aurora was developed and flew but either proved an ultimate design failure or was too expensive, as Simon stated, to build an entire fleet of them.

One of my professors in engineering school claimed to have worked on Aurora, and he certainly had the resume complete with an NDA gap. According to him, "Aurora" was a technology demonstrator and testbed for a number of new technologies that were expected to be used in 4th and 5th generation fighters, high altitude hypersonic bombers, and spy planes. And it proved to be a failure. My professor said that they only built and flew 2 Auroras with a partially constructed 3rd prototype sitting in a storage hangar at Wright-Patterson AFB in Ohio last time he checked in the early 90s. The planes were mostly off-the-shelf parts taken from other high speed high altitude aircraft, including the A-12 and SR-71. The only interesting components were a camera designed for hypersonic recon (which ultimately didn't work) and J-58 engines modified with an additional mode after the ram jet. In this third stage the j-58 engines served as the compressor and fuel mixer for an early pulse detonation engine, which produced the iconic contrails. The pulse detonation stage burned a mix of JP-1 and isoborane ("zip fuel") leftover from the "Boron Boom" and B-71 era of the 1950s. The USAF bought a few hundred thousand gallons of several isoboron fuel mixes before it was discovered that stuff can't be used safely in a turbine engine, so the development contract stipulated that Aurora and a few other black projects used it. If it was successful there were plans to restart isoborane fuel programs in the late 80s. According to my professor the Aurora quickly proved to be an impressive disappointment as while the cobbled together aircraft and the exotic new engines performed incredibly well, it proved that both hypersonic reconnaissance and bombing were impractical to impossible. The behavior of atmospheric gases around a hypersonic aircraft proved to be chaotic, and the technology to compensate for it is still decades away. Hypersonic reconnaissance with photos or electronic equipment didn't work because of the ionization of air around the aircraft. Air becomes superheated, glowing first red than blue, which also releases a storm of high energy electrons around the aircraft. The electrons in term release radio waves as they drop down to a ground state around normal atoms. Those radio waves blind electronic surveillance equipment and gave the Aurora a massive radar signature that "a blind operator could see in the dark". Essentially the same thing that happens when spacecraft reenter the atmosphere ("Blackout"). The camera couldn't see through the glowing gases or compensate for the ground speed. Hypersonic bombing proved to be a failure because of the turbulence experienced by a bomb decelerating from hypersonic velocities. A nuke could be dropped hundreds of miles away from the target with all the momentum to hit, but would do so with less accuracy than WW2 era strategic bombing. ICBMs proved more effective. My professor said that the Auroras did achieve the highest velocities of any manned jet plane ever, but they never actually conducted record setting flights. You have to meet certain mission requirements to set an official speed record (closed course, both directions, multiple agencies corrobating the event), and the secrecy of the program required they avoid attracting attention. The fate of the two Auroras was grim, unfortunately. They both exploded due to problems with the isoborane fuel. The first aircraft exploded over the Pacific Ocean somewhere between Hawaii and California during a "high speed research flight" (just flying the expensive things because they had the money and aircraft just sitting there) in 1989. They never found the wreckage. The second prototype exploded just after takeoff due to a likely fuel leak in 1990. The pilot, who was killed in the explosion along with the copilot/flight engineer, was the son of a "wealthy and well connected United State congressman" (my professor didn't actually know who, and regarded the pilot as what we now call a "nepo-baby"). The destruction of the second prototype also happened while a number of ranking military brass were present at the airfield to witness see the Aurora. After the second disaster the program was canceled. Test flights using smaller versions of the engines on unmanned drones were planned to continue in the mid to late 90s, but my professor left "the company" (presumably Lockheed-Martin) in 1992 and lost his security clearance accordingly. My professor regarded the Aurora project as a waste of time and money, and said he would have preferred to have worked on the F-22.

In the 90s, I was working as a sparky in New Malden for BAE systems. On the 9th floor, it was divided into sections, Project Aurora Flight systems etc etc. Didn't really pay any attention until one day I was sitting in the Tearoom eating a bacon sarnie and reading the paper. When I came across an article saying 'BAE systems deny all knowledge of project Aurora'

In the late 80s/early 90s techno-thriller author Tom Clancy would participate in public roundtable chats on GEnie (an early online service). In one of those chats, a user asked Tom about the cancellation of the SR-71 program. Tom recounted that his sources in the military had told him about “Aurora”, that it operated out of Groom Lake, and that it was Mach 4.5+ capable. Source is me. I asked him the question. Having Tom Clancy answer my question with such a cool answer is of my childhood geek out best memories. I wish there was an archive of the GEnie roundtables.

My dad was in fuels for the Air Force 1970-1997. He was picked up by the DOD for about another 17 years and became fuels branch manager at NAS Corpus Christi. About 4-5 years ago we were at my parents house for the holidays and I was telling my brother how I saw a contrail that looked like donuts on a rope and my dad pops into the conversation to say “they don’t fly of Texas.” Got an Oh shit look on his face. He legitimately got a job offer for groom lake but choice German instead in the mid 70s.

Back around 1990 there was talk about 'external combustion' aircraft that would use the supersonic shock cone to contain a fuel explosion behind the aircraft for propulsion. At P&W we worked on lots of 'Black' programs out in the General Shop as small bits and pieces normally wouldn't arouse any suspicions as to where they went or what they did....the only clue was that the work order # always began with an 'X'. I had a bank of small rocket nozzle looking things that needed some work and had just heard about the 'external combustion' theory and mentioned this to the engineer overseeing this piece...and me saying those words made the color drain quickly from his face and I ended up needing to go talk to Security about it. Was basically told to shut up, don't think and quit trying to figure out things....or else. OK!!! I'm dense but got the message. The 'external combustion' deal might very well be what caused the 'donuts on a rope' exhaust trail. And this is just the kind of experimental stuff that they do ALL the time...the 'what would happen if' guys that build and test and even when/if it doesn't turn out to be a feasible concept they get lots of data from it that will be useful elsewhere. We were working on SCRAM engines back in the 1990 time frame too among other neat things. Someday we might find out what was going on once the information is no longer relevant to contemporary machines.