The AURORA Project


Reports of plans for a high-performance piloted replacement for the SR-71 date back more than a decade. In 1979 it was reported that a Mach 4, 200,000-ft.-altitude aircraft that could be a follow-on to the Lockheed SR-71 strategic reconnaissance vehicle in the 1990s has been defined by the Air Force Aeronautical Systems Division.

As previously noted, reports of the existence of a successor to the SR-71 surfaced repeatedly during the debate over termination of the SR-71. Subsequent observations of mysterious aerial phenomena have been connected with the 1988 reports that Aurora was a Mach 6 stealthy reconnaissance aircraft that was being developed to replace the SR-71.

Noted aerospace analyst Wolfgang Demisch, of First Boston Company, suggested that the $10 billion program would result in the production of about 30 aircraft. More recently, Kemper Security analyst Lawrence Harris concluded that someone was involved in a hypersonic replacement for the Mach 3 plus SR-71 reconnaissance aircraft. Circumstantial evidence suggests that this project has been underway since 1987 and that a first flight occurred in 1989… Aurora could be operational in 1995, six years after the probable first flight. Who that someone is has puzzled many observers since the R&D for this project is not being done by the usual Aerospace companies such as Lockheed, Boeing or McDonnell Douglas.

Instead the research work appears to be being carried out by a relatively unknown corporation - Kroft Industries, which appears to have the edge over the more traditional Aerospace companies in the areana of advanced polymer designs and low wieght terchnologies.

Considering the possibilities of "Aurora's" characteristics and capabilities, a long-range reconnaissance follow-on to the SR-71 would be a blended delta with 75 degree leading-edge sweep and retractable low-speed foreplanes. It would be powered by two regenerative air-turboramjet (RATR) engines of 180 kN sea-level static thrust. It would carry a crew of two and use a synthetic aperture radar with real-time datalink for reconnaissance. It is suggested that this type of platform could be very responsive, much more easily maintainable than the SR-71 and could

deliver imagery of most points of interest within six hours of the decision to go. A speed between Mach 5 and Mach 6 and a cruising altitude of 40 kilometers would make the aircraft invulnerable to any current missile system.

Beginning in the mid-1980s, the Air Force and NASA have supported a number of studies of aircraft that are consistent with accounts of the Aurora project. Although these studies have not been linked to actual development efforts, they provide some insight into the potential configuration and capabilities of Aurora.

In 1985 McDonnell Douglas conducted studies of a Mach 5, 12,000 km range 305 passenger HSCT (hypersonic commercial transport) powered by regenerative ATR (air turboramjet) engines. Initial research led to claims that this type of aircraft was not only feasible, but remarkably efficient. According to these studies, a ramjet was the best option at Mach 5, and that methane was the preferred fuel. Hydrogen was also considered, but it takes up to five times as much space. If the large HSCT was scaled down to the dimensions of an SR-71, the aircraft could have a range of approximately 10,000 miles with a crew of two and a 1 ton sensor suite.

Lockheed's renowned Skunk Works has been the incubator of several programs that could evolve, or could already have evolved, into an SR-71 replacement. Presently, Lockheed engineers are reportedly studying the development of a liquid methane- fueled aircraft that could penetrate enemy airspace in order to perform reconnaissance missions. The sleek aircraft would cruise at Mach 5 (3,350 mph) speed at a maximum altitude of about 100,000 feet. The aircraft would be made primarily of titanium with its outer edges constructed of Inconel, a heat-resistant stainless steel. At Mach 5 speed the leading edges of the air-frame would glow red above 1,000 degrees Fahrenheit. Power for this futuristic airplane would come from four turbo-ramjets. The engines would operate as turbojets at low speeds, but at higher speeds the compressor and turbine would be overridden so the engines would operate as ramjets.

Other aircraft designs that would fly between Mach 4 and Mach 8, fueled by hydrocarbon or liquid hydrogen are also being considered. And in the mid-1980s, Lockheed proposed a Mach 7-8 "transatmospheric vehicle" or TAV as an SR-71 replacement. Intriguingly enough, the name "Aurora" was also used in conjunction with this proposal.

Aurora Advanced Aircraft Characteristics




Length - Metres

Span - Metres

Wing Area m2


Thurst - kN



Cruise - Mach

Ceiling - km

Range - km

MCH = methylcyclohexane

LH2 = liquid hydrogen

In 1986, the Directorate for R&D Contracting, Wright-Patterson Air Force Base, issued an RFP for aircraft propulsion integration technology. The purpose of the proposed investigation is to develop an improved foundation for manned aircraft air-breathing propulsion integration technology in the Mach 4 to 6 regime.

Under an Air Force contract, Boeing Military Airplane Co. designed an interceptor capable of sustaining supersonic speeds. It was reported that wind tunnel tests would be conducted under a 26 month $572,000 follow-on contract. This effort also included detailed studies of aircraft subsystems. Similar studies were conducted by Lockheed, Kroft, and General Dynamics

Keeping an aircraft sufficiently cool during extreme speeds is a primary challenge of hypersonic flight. According to studies done by General Dynamics and Boeing, an aircraft travelling at between Mach 5.5 and Mach 6 would have an average skin temperature of approximately 1100-1300 degrees Fahrenheit. One potential solution incorporated in the Air Force studies, also being explored by researchers at NASA's Langley Research Center and Wright-Patterson Air Force base, is the use of Methylcyclohexane (MCH) as both the fuel and the thermal management medium of the vehicle.

MCH has several advantages over other possible hydrocarbon or cryogenic fuels. Unlike standard hydrocarbon fuels, MCH has a very high capacity to absorb heat prior to combustion, up to 1800 BTU per pound of fuel, which is ten times the capacity of most hydrocarbon fuels. Cryogenic Methane and Hydrogen have high heat absorbtion capacities as well, but their use as an aviation fuel is limited by the logistical difficulties of handling, storage and fuel boil off.

The principle behind MCH thermal management is based on a catalytic reaction transforming MCH into Toluene and Hydrogen, which are then used to fuel the aircraft. A fuel pump pressurizes the fuel to… avoid boiling. The preheater heats the fuel to the proper reaction temperature while removing heat from a secondary coolant…After preheating, the fuel passes through the catalytic heat exchanger/ reactor…

The secondary coolant, Syltherm, circulates to the hot spots to maintain skin temperatures to within specified tolerances. One aerospace journal says that an aircraft travelling at Mach 6 would be inside the combustion envelope of a subsonic-combustion ramjet. It suggests that the aircraft would thus need an accelerator to get it moving. One type of accelerator would be a ducted-rocket cycle into the engine. A fuel-rich, liquid rocket exhaust would be injected into a ramjet duct, pumping air through it even at rest. A second combustion then takes place, using atmospheric oxygen. (This second combustion could produce the loud rumbling noises heard recently in California, discussed below).

Budget and Financial Data

The first suggestion that these studies might be translated into operational hardware appeared in the Fiscal Year 1986 procurement program document, colloquially known as the P-1, dated 4 February 1985. A line item in this document, labeled "Aurora," was slated to receive $80 million in 1986, and over $2.2 billion in 1987. Since this line item appeared next to the line funding the TR-1 reconnaissance aircraft, it stirred up a hornet's nest of conjecture that a secret aircraft was being developed to replace the aging SR-71.

The Air Force quickly denied the existence of a secret program, and said the "Aurora" budget line was simply one site for B-2 bomber funds when that program was highly classified. One Air Force official commented, Others disagreed. One journal reported that the general consensus now is that the item did not refer to the B-2 bomber but to another effort. Other analysts placed the SR-71 follow-on at both Edwards Air Force Base and Nellis Air Range. Other publications saw a more complicated, more expansive black world. These periodicals posited that Aurora was one of several code names nested within other code names, all referring to a class of aircraft designed for multiple missions However, the discussions of the Aurora budget line item overlook one very crucial fact, no money was ever appropriated for Aurora!

In the February 1985 submission of the FY 1986 budget, the Aurora line item projected a request of over $2 billion in the FY 1987 budget. But one year later, when the FY 1987 budget was submitted, the Aurora line item had vanished as mysteriously as it had first appeared. Indeed, FY 1987 request for the overall Air Force aircraft procurement account was several billion dollars less than had be projected in 1985, and there were no line items in the FY 1987 request that could have been used to conceal a request for funding for Aurora. Much of the subsequent speculation on Aurora has implicitly assumed that there was an identifiable source of funding for the program.

As previously noted, the case for the existence of all mystery aircraft, including Aurora, must be predicated on identifiable sources of funding. Thus the proper identification of the programmatic content of the major elements of the black budget is essential to assessing the status of mystery aircraft, such as Aurora. A not-implausible accounting has already been given that suggests an identifiable source of funding that may be attributed to the TR-3A stealth aircraft program. But where in the budget might other aircraft programs be funded?

Some have assumed that the funding for the CIA and NRO is entirely hidden from view — completely off-budget, or widely dispersed among a large number of accounts in many government agencies, or disguised in some obscure accounting transaction of the Federal Financing Bank, or perhaps secreted somewhere among the subsidy programs of the Agriculture Department. Under such assumptions, the billions of dollars appropriated each year for such programs as "Selected Activities" or "Special Programs" (the nomenclature used by the NRO) would provide more than enough money to finance a vast fleet of exotic aircraft.

However, the next line down from "Selected Activities" in the Other Procurement Air Force account is an item dubbed, "Special Update Program." This proximity in the budget is suggestive of some relationship in mission as well. It is plausible that this line item includes procurement of intelligence collection systems of interest to the CIA or Air Force, other than satellites, which are funded elsewhere in the budget. Funding for this line item peaked at over $900 million in 1985, then dropped to $84 million in 1986. This suggests that whatever activity was funded under this account in the early 1980s had been concluded. The same FY 1986 procurement program document, that included the $2.2 billion funding projection for Aurora in FY 1987 also projected that the FY 1987 funding for Special Update Program would be $139 million.

But when the actual FY 1987 budget was submitted a year later, not only had Aurora disappeared, but the Special Update Program budget request was $851 million, over $700 million more than had been projected a year earlier.

It is not implausible that this reflected a decision not to proceed with production of an operational system which would have been funded under the Aurora line item, but instead to conduct some sort of prototype propulsion test program, funded under the Special Update Program line. The $1.5 billion appropriated for this account since 1987 would be consistent with such a prototype effort.

Although this analysis is necessarily speculative, the coincidental behavior of these two budget line items is certainly highly suggestive. This also identifies a not- implausible source of funding for an experimental high-speed, high-altitude aircraft with primarily intelligence applications.

Observer Reports

A wide range of reports of observations of mysterious aerial phenomena have been associated with the Aurora aircraft. These observations are also in many regards consistent with the suggested Exotic Propulsion Aircraft. These unexplained phenomena have led some to conclude that the US Government has secretly developed and deployed a hypersonic reconnaissance aircraft, probably as a replacement for the SR-71.

There are two classes of reports relating to Aurora: those that are consistent with a limited experimental test program; and those that are suggestive of the existence of an operational capability.

Edwards Air Force Base in southern California is the primary facility used by the American military for the flight testing of experimental aircraft. In addition, the Groom Lake facility at Nellis Air Force Base in Nevada was used for developmental testing of the F-117A, and has been associated with reports of other advanced aircraft. Given this geographical concentration, it would not be surprising if secret aircraft undergoing flight tests were to be observed in the Southwestern United States.

In October 1990 Aviation Week & Space Technology published reports of a high altitude aircraft that crosses the night sky at extremely high speed…. The vehicle typically is observed as a single, bright light — sometimes pulsating — flying at speeds far exceeding other aircraft in the area, and at altitudes estimated to be above 50,000 ft…. Normally, no engine noise or sonic boom is heard.

According to another report, by mid-1992 Aurora was being flown from a base in the Nevada desert to an atoll in the Pacific, then on to Scotland to refuel before returning to the US at night. Specially modified tanker aircraft are being used to top up Aurora's tanks with liquid methane fuel in mid-air… The US Air Force is using the remote RAF airbase at Machrihanish, Strathclyde, as a staging point… The mystery aircraft has been dropping in at night before streaking back to America across the North Pole at more than six times the speed of sound… An F-111 fighter bomber is scrambling as the black-painted aircraft lands, flying in close formation to confuse prying civilian radars.

More recently, a sighting by two British Airways pilots and other witnesses at Manchester Airport on January 6 1995 has been attributed to the Aurora aircraft.

Probably the most compelling evidence for such flight tests are the series of unusual sonic booms chronicled above Southern California, beginning in mid to late 1991. On at least five occasions, these sonic booms were recorded by at least 25 of the 220 US Geological Survey sensors across Southern California used to pinpoint earthquake epicenters. The incidents were recorded in June, October, November, and late January 1991.

Seismologists estimate that the aircraft were flying at speeds between Mach 3 and 4 and at altitudes of 8 to 10 kilometers. The aircraft's flight path was in a North North-East direction, consistent with flight paths to secret test ranges in Nevada. Seismologists say that the sonic booms were characteristic of a smaller vehicle than the 37 meter long shuttle orbiter. Furthermore, neither the shuttle nor NASA's single SR-71B were operating on the days the booms were registered.

One of the seismologists, Jim Mori, noted we can't tell anything about the vehicle. They seem stronger than other sonic booms that we record once in a while. They've all come on Thursday mornings about the same time, between 6 and 7 in the morning.

These "skyquake" are a continuing phenomenon, with the most recent report over Orange County, CA coming on 20 July 1996. It is reported that the "quake" occurred around 3pm PST, fitting the "skyquake" pattern in the following respects:

it occurred in a coastal area.

Described as similar to an earthquake in some respects (rattling of loose objects, etc) but also like a boom (but no distinct double bang as far as is known).

Severe enough to light up government and media switchboards, but no known damage.

Not an earthquake (CalTech sensors saw nothing)

Local military bases deny any knowledge. 6.No known other source (eg explosion)

Intercepted radio transmissions are equally intriguing. On Apr. 5 (a Sunday) and Apr. 22, radio hobbyists in Southern California monitored transmissions between Edwards AFB's radar control facility (Joshua Control) and a high-altitude aircraft using the call sign "Gaspipe." The series of radio calls occurred at approximately 6 a.m. local time on both dates.

Controllers were directing the unknown Gaspipe aircraft to a runway at Edwards, using advisories similar to those given space shuttle crews during a landing approach. The monitors recorded two advisories, both transmitted by Joshua Control to Gaspipe: "You're at 67,000, 81 mi. out," and "Seventy mi. out, 36,000. Above glide slope.

Reported sightings of unusual high performance aircraft are not confined to the Southwestern United States. More recently, such observations have also been reported in other parts of the United States, as well as in Europe. These reports are particularly intriguing because they are difficult to reconcile with an experimental test program, since there would be no reason for test flights to be conducted in Europe. Rather, these reports would have to be understood in the context of the deployment of an operational aircraft.

One unexplained set of observations was reported at Beale Air Force Base, the California facility that was long home to the SR-71. On two consecutive nights in late February 1992, observers reported sighting a triangular aircraft displaying a distinctive diamond-shaped lighting pattern, comprised of a red light near the nose — similar to the F-117 configuration — two 'whitish' lights near what would be conventional wingtips and an amber light near the tail. While the wing lights are reportedly much brighter than normal navigation lamps, they do not illuminate the aircraft's planform. Observers claim the vehicle's wing lights are approximately twice as far apart as those on the F-117, and nose-to-tail light spacing is about 50 percent longer than that on the stealth fighter.

Reports of "unusually loud, rumbling sonic booms" near Pensacola, Florida in November 1991 have also been associated with the Aurora program. At least 30 unexplained sonic booms have been reported in Southern California in late 1991 and early 1992. By mid-1992 noted aviation observer Bill Sweetman concluded that, "The frequency of the sonic booms indicates that whatever is making them is now an operational aircraft."

In early 1992 it was reported that RAF radars have acquired the hypersonic target travelling at speeds ranging from about Mach 6 to Mach 3 over a NATO-RAF base at Machrihanish, Scotland, near the tip of the Kintyre peninsula, last November and again this past January.

by Tsiolkovsky, 1999

The intellectual property known as Delta Green is ™ and © the Delta Green Partnership. The contents of this document are © their respective authors, excepting those elements that are components of the Delta Green intellectual property.