SR-71 top speed

[outlaw162]

Look at it this way, if in a level turn at FL800, that mach 3.2 turn radius of 50 NM at 44 degrees of bank requires a bone-crushing 1.4 Gs....

....and these guys didn't wear g-suits.

(maybe not all of Texas haha , but a sizable portion of I-35, including the never-ending construction....what happens when the sun burns out? They'll have to finish I-35 in the dark)

[sferrin]

Or as we say in Utah, "there are only two seasons; winter and road construction."

[charlielima223]

https://theaviationgeekclub.com/we-coul ... d-run/amp/

Another fun article. Here is a teaser to all the sled fans at the very end of the article

However, once the engine was restarted after the inlet unstart, Joersz and Morgan could’ve pushed the Blackbird to the limit and gone Mach 3.3, but in 1976 they really didn’t want anyone to know how fast the SR-71 could go. It was still classified. For this reason, the US Air Force (USAF) chose to set the speed record “very carefully” avoiding to disclose how fast the SR-71 could really go.

Thats not fuel she is leaking, those are tears. She is only happy when she is flying high and fast.

[charlielima223]

A very good presentation of the P&W J58

at time index 19:10 he states teh pilot pushed the aircraft up to mach 3.4.

ENJOY!!

[edpop]

NASA's X-43A aircraft flew more than nine times as fast on Nov. 16, 2004, flying Mach 9.6 or almost 7,000 mph. That stands as the fastest speed achieved to date by a jet-powered aircraft.

[f119doctor]

A very good presentation of the P&W J58

at time index 19:10 he states teh pilot pushed the aircraft up to mach 3.4.

ENJOY!!

Arnie Gunderson is a very knowledgeable individual and was great to work with. When he shares information regarding the J58, you can take it to the bank.

The interesting detail in this video is the that M3.4 was the limit of the spike aft translation to control the terminal normal shock in the SR-71 mixed compression inlet. Unless there was a subsequent modification to the inlet, that pretty much sets the top speed limit. There may be some slight variation due to air temperatures at cruise altitude, but it won’t be much.

I also noticed that Arnie never made it back to the bleed bypass system on the J58….

[edpop]

The speed of sound at sea level is 761 MPH and at 35000 ft it is 660 mph give or take a mile an hour or so depending on outdoor temp.

[sprstdlyscottsmn]

Sea level 1116ft/s
36000ft-65000ft 968ft/s
80000ft 978ft/s
90000ft 985ft/s

the speed of sound goes up at Blackbird altitudes

[f119doctor]

Perhaps I should have said top Mach number, not top speed....

At the design cruise point of M3.2, 80K, the standard day air temp is approximately -62F, plus or minus 10F depending on local conditions. The speed of sound in air varies with the square root of the absolute temperature ratio to standard day temperature (square root of Theta), so the M1 velocity numbers quoted are a close approximation of the actual speed of sound at the SR-71 cruise altitudes.

My point was that the mechanical geometry of the SR-71 appears to limit the Mach number to around 3.4 before it cannot control the positions of the shock waves in the mixed compression inlet necessary for stable and efficient pressure recovery. Any faster, the inlet unstarts and the pressurized air supply to the engines is disrupted. This makes sense that Lockheed designed some margin for the inlet system to work at Mach numbers higher than the design cruise point, but not beyond M3.4. I don't think that ambient air temps change the angle and position of the shocks inside the inlet, but they are completely dependent on the inlet Mach number and turning angle, and keeping the multiple oblique shocks and terminal normal shock in the correct and stable locations depended on the position of the inlet spike and inlet bleeds.

The plus or minus 10F variation in ambient temperature at cruise had a large impact on the performance of the aircraft, according to Col Richard Graham in his book "SR-71 Revealed". On a "cold" day, the aircraft flew faster and burned less fuel, being able to maintain cruise Mn at partial AB. On a "hot" day, the greater amount of fuel needed to maintain cruise was significant. Having accurate forecasts for the temperature at 80K was a major mission planning factor.

[charlielima223]

I dont know where else to put this but a heavy loss to the aviation community...

A very well known speaker in the aviation community, Vietnam veteran, and an avid photographer.

https://theaviationist.com/2023/05/24/t ... lown-west/

I met the man a couple of years ago at Nellis AFB during their open house event. I have a signed autograph by him of an SR-71 picture. The single moment I was able to meet him was something I will always remember. He loved flying and most of all he loved the community of people in itas well as the fans. I dont remember where I heard or read it but I told him something about the SR-71 and he had a big grin on his face at the end telling me that is one of the best things he has ever heard.

"The SR-71 isn't leaking fuel when she is on the ground, she is crying. The only time when she is happy is when she is flying high and fast".

Chuck Yeager broke the sound barrier when he went through those pearly golden gates while Brian Shul left the angels breathless trying to keep up.

RIP Mr Shul

[Gums]

Salute!

Well, gotta chime in here as Brian was one of my students at Air University a few years after his terrible crash and fire thing. He was also from my favorite squad at the Beach - the 356th Green Demons.

You must remember that since 1977 that cosmetic surgery and such has really helped Brian to look lots better than the first day at class when he walked in and introduced himself. I have his autographed first book about the two or three dozen operations and his painful recovery from that crash and the fire.

A few years after meeting him, he had a tour of many fighter wings and talked about fire protection you could take no matter what the official books said. So he shows up at Hill for our friday "safety" or whatever deal was before happy hour. He liked that our wing had adopted turtle necks for the squads and noted that even cotton would help reduce burns, but wool was better. The interesting thing was the nomex was good for instant fire, but if the fire was more than 10 or 15 seconds, then it got hot! His hands were a great example, as the NOMEX backs were terrible from the flying gloves, but the leather fingers and palms were just like you and I. Doing a lot of athletic stuff his legs were good examples of fire mitigation - his thighs showed clear lines where his gym shorts were, as on his bad mission he was called off the tennis court to help with a CAS mission, still wearing the shorts. Ditto for his ankles due to his wool or heavy socks. He said that running across a burning wing was not all that bad and sat down after getting clear. Then he got really hot, as the nomex was 'fire resistant", but got hot and that was what burned him most of all.

So another nickel on the grass, my friend, hope to meet you one day at that neat stag bar somewhere in time/space.

Gums sends...

[charlielima223]