[This message has been edited by Larryinkc (edited 12-27-2024).]

I have always been into aircraft- my father working at NAS Alameda on aircraft- and then, after the Navy, I worked there for 15 years....I read a book about the SR-71 with some interesting info;

A number of things are very amazing about the SR-71...Obviously. it is the fastest (Air-breathing) aircraft in the world- even after 60 years since first flight.

But some details are simply ridiculous;

A) The engines are very powerful- but they create less than 20% of the thrust needed at Mach 3....the afterburners create more...but the INTAKES create 60% of the thrust at Mach 3!

Details; Back then fuel could not be injected into a supersonic air flow- so the intake actually decelerates the air from Mach 3 (2300 mph) down to under 700 mph before reaching the engines...anyone who knows aerodynamics- specifically the Venturi effect- knows that FASTER air creates low pressure- and, of course, slowing air down creates...HIGHER pressure. So they designed the intake to slow the air and then take advantage of the higher pressure this created to generate thrust!

Minor detail- the plane is more fuel efficient at Mach 3 than at Mach 2....

B) The skin temperature of an SR-71 at Mach 3 is 600-1000 degrees! The leading edges get the hottest....but what is really amazing about this is that the fuel tanks LEAK at lower temperatures...so a typical mission requires a tanker aircraft to precede along the route....the '71 is partially filled, then takes off and DASHES at Mach 3 for short distance to heat the skin (Expanding it and sealing the leaks) and then rendezvous with the tanker and fills up...I have seen pics taken from the tanker showing the '71 leaking during fill-up; first at the trailing edges, then midway up the wings and then all the way to the leading edges. (Note; the SR-71 flys at a high angle-of-attack at refueling speeds so the fuel fills back-to-front in the wing-tanks)

C) The edges of the fuselage and wings are actually very odd in their internal design- the metal structure zig-zags, and the triangular gaps are filled with a material that absorbs radar-waves, helping to make the SR-71 invisible to radar; A number of times SR-71s either had to fly near civilian airports or make emergency landings at those airports....the Controllers would be watching the radar screens, then suddenly they would get a call from an aircraft...looking at the screen they could not see it until it was within a mile of the tower/radar....(Of course it definitely is not invisible to Infared sensors!)
C-2) The edges of the fuselage also help aerodynamically; Those edges create vortices that pass over the wings- a rotating vortex creates LOW-pressure, so this increases the lift of the wings- especially at high angles of attack to help with landings and take-offs.




D) That intake has a number of vents and doors inside to control airflow- but the big spikes sticking out the front are the most critical thing; They move fore & aft to keep a shockwave from the tip of the spike just inside the lip of the intake....usually works well- but, there was a lot of learning in the beginning- if the spike moves too far forward, the shockwave exits the intake and then hits the wing...this can lead to all sorts of problems- including massive deceleration- and because the engines are positioned far apart, this can create an extreme rotation/deflection of the aircraft from it's course. (A pilot had this happen- he was thrown laterally through the side of the cockpit/fuselage......he survived- but his crewmate was killed instantly (broken neck)




I was lucky enough to have a friend who was in the Air Force- he took me to an airshow at Beale AFB in N. CA- One of the best airshows I ever attended.....some really cool aircraft including an F-15 and some T-38s...But, of course, the best was an SR-71 taking off and doing a flyby- and yes, it was leaving a trail of fuel behind it!

[This message has been edited by cvxjet (edited 12-29-2024).]

Pretty damn amazing for 1960's technology!

[This message has been edited by Patrick (edited 12-29-2024).]