Garry

Noone has argued the SR-71 is undetectable. Its combination of speed, altitude and reduced radar cross section made it effectively invulnerable to SA-2, however. Even against SA-5 or SA-10/12, it would be a tough target to hit.

Well Sean, there is no point arguing with some of the people here. Apparently their own opinions rate higher than those of the designers of the actual planes.

During the fall of 1957, Bissell, still convinced the U-2 would have a short service life, contacted Johnson and asked if the Skunk Works team would conduct an operations analysis to determine how far the probability of shooting down an aircraft varied respectively with its speed, altitude, and RCS. Johnson, already immersed in related studies, agreed to accept the project.

The resulting analysis concluded that supersonic speed coupled with the use of radar attenuating materials and radar attenuating design considerations greatly reduced the chances of radar detection…though it did not reduce it to zero.

…which we could obtain with a version of the A-11 adapted in shape and treatment to reduce the cross-section. I proposed the A-12 with the J58 engines in a mid-wing arrangement, the use of chines on the fuselage and serrations on the leading edge incorporating radar treatment.

Another major problem was radar cross-section. The areas causing the most RCS difficulty included the vertical stabilizers and the forward section of the engine nacelles. Lockheed conducted considerable research into the use of ferrites, high-temperature radar absorbing materials, and high-temperature plastic structures to find methods for reducing the RCS. Eventually, the vertical tails, originally of titanium, were replaced by units of high temperature composites.

Lockheed Skunk Works, Jay Miller.

You mean M-53 or “Super Atar” as it was known initially has nothing to do with Atar? Interesting choice of name then 😉

M53
Inlet diameter = 0.796 m
Max diameter = 1.055 m
Length = 5.07 m
Mass flow rate = 94kg/sec
Weight: 1515kg
A/B Thrust: 9704kg
Dry thrust: 6577kg

Pressure ratio: 9.8:1
BPR: 0.36
T/W Ratio: 6.4
TET: 1327 deg C
SFC: 2.1 A/B, 0.9 Dry

In terms of a fit, the F100-PW-220 isn’t too bad (bit wider, but not by much); mass flow rate is a bit higher (100kg/sec +) which would require bigger inlets.

PW1120, as used on Lavi, gives similar thrust from a smaller engine that needs less air and is quite a bit lighter.

AL-31F weighs about 15kg more, but needs a lot more air (112kg/sec) and at 1.22m diameter would need a wider fuselage. Greatly increased thrust though.
Fuel burn rate is actually lower in military thrust despite the higher thrust levels, but higher in afterburner.

RD-33 would fit easily, but needs only 77kg/sec mass flow and gives less thrust, though it has lower fuel consumption and would save about 500kg in weight.

Its hard to believe just how low tech M53 is. The AL-21F-3 turbojet achieved 14:1 compression ratios….

Its a pun. “MFI” is a shop in the UK that sells flat packed furniture, a bit like Ikea.

Lyulka AL-41F was designed for supersonic cruise from the beginning. Thought to be variable cycle like the F120.

Sferrin was alluding to the conspiracy theory that the US published lots of canard delta artworks to deceive others into going down a dead-end route they had no intention of going down themself.