OXCART SR-71/A-12 performance comparisons

Gridlock said:
Mach 3.2, but stick to 3.0 or the wings come unglued.
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Note, that was "current" as of 1967. It regularly flew at it's design point of Mach 3.2.
 
The test pilots on both said the A-12 was a lot faster.
 
Johnbr said:
The test pilots on both said the A-12 was a lot faster.
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Sure. That doesn't change the fact that the SR-71 regularly flew at it's design point of Mach 3.2 without the wings coming off. I've seen as high as Mach 3.6 quoted for the A-12 and a sustained 97,000 feet.
 
sferrin said:
Sure. That doesn't change the fact that the SR-71 regularly flew at it's design point of Mach 3.2 without the wings coming off. I've seen as high as Mach 3.6 quoted for the A-12 and a sustained 97,000 feet.
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97,000 feet I've heard before, Mach 3.6 would depend on the CIT. Don't know if they would ever "sustain" an altitude though, given that the jet tended to climb as it burned gas during Mach 3 cruise. Operationally they flew at the max range altitude for their given speed and weight, so as fuel was burned and the jet got lighter they climbed.

Also, the A-12 did manage to cruise at design speed operationally, the only difference being that politics killed it off way, WAY too early.
 
SOC said:
sferrin said:
Sure. That doesn't change the fact that the SR-71 regularly flew at it's design point of Mach 3.2 without the wings coming off. I've seen as high as Mach 3.6 quoted for the A-12 and a sustained 97,000 feet.
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97,000 feet I've heard before, Mach 3.6 would depend on the CIT. Don't know if they would ever "sustain" an altitude though, given that the jet tended to climb as it burned gas during Mach 3 cruise. Operationally they flew at the max range altitude for their given speed and weight, so as fuel was burned and the jet got lighter they climbed.

Also, the A-12 did manage to cruise at design speed operationally, the only difference being that politics killed it off way, WAY too early.
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"Sustained" as in it wasn't just a zoom-bump but were able to stabilize at the altitude.
 
The A-12 was designed for Mach 4 at 120,000ft. It didn't reach that goal, but IIRC it did achieve M=3.82, but I don't know at what altitude that was achieved. The SR-71 achieved M=3.7x on a run over Hanoi. However, they had to be cleared from Washington, D.C., to go over M=3.5 since it would ruin the engines.
 
Sundog said:
The A-12 was designed for Mach 4 at 120,000ft. It didn't reach that goal, but IIRC it did achieve M=3.82, but I don't know at what altitude that was achieved. The SR-71 achieved M=3.7x on a run over Hanoi. However, they had to be cleared from Washington, D.C., to go over M=3.5 since it would ruin the engines.
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Where are you getting this from?
 
The performance they actually flew is from Paul F. Crickmore's books on the Blackbird. I can't remember where I found the design specs for the Blackbird. I don't know if it was Ben Rich's book or one of my engineering papers.

IIRC in PFC's books, Blackbird pilots were allowed to normally go up to M=3.2 If they needed to they could push it to M=3.4. But above M=3.5 they needed permission as I noted above.
 
SOC said:
Also, the A-12 did manage to cruise at design speed operationally, the only difference being that politics killed it off way, WAY too early.
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According to the document posted by Gridlock, the big difference between A-12 and SR-71 was the sensor suite. What good is the extra speed if you need 3 A-12 sorties instead of one SR-71 sortie?
 
Sundog said:
The performance they actually flew is from Paul F. Crickmore's books on the Blackbird. I can't remember where I found the design specs for the Blackbird. I don't know if it was Ben Rich's book or one of my engineering papers.
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Pretty sure you've got OXCART confused with FISH. Convair's FISH was the Mach 4 parasite jet competing against Lockheed's early designs before all of the contenders were basically thrown away. Lockheed came back with the A-11/A-12, and Convair came back with KINGFISH. OXCART was never intended to be a Mach 4 platform.

Sundog said:
IIRC in PFC's books, Blackbird pilots were allowed to normally go up to M=3.2 If they needed to they could push it to M=3.4. But above M=3.5 they needed permission as I noted above.
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Mach 3.2 was the design speed for the SR-71A. But...Mach number varies with temperature and altitude, so a more appropriate way to think of the performance is in relation to the engine CIT. I've never heard of an SR-71A going Mach 3.7 over Hanoi, and I've got everything Paul has written. Plus pretty much all of the other Blackbird books. There was one weird Hanoi overflight, but it happened at a much lower speed and altitude than planned due to engine issues. They ended up at Mach 1.7 and 41,000 feet over Hanoi, not someplace they really intended to be! Maybe you confused Mach 1.7 with 3.7?
Hobbes said:
According to the document posted by Gridlock, the big difference between A-12 and SR-71 was the sensor suite. What good is the extra speed if you need 3 A-12 sorties instead of one SR-71 sortie?
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They were designed to do different things. The A-12 was a survivable photographic intelligence platform for the CIA to replace the U-2. The USAF needed the SR-71 to gather more types of intel, so it had a more varied sensor suite. That being said, the camera in the A-12 was often better performing than the smaller cameras in the SR-71, and they were working on SLAR and ELINT packages for the A-12 when the program was cancelled. The A-12 did have a semi-ELINT capability, but it mainly consisted of gathering signals that painted the jet as opposed to sniffing out everything it could find.
 
You are familiar with the World Record top speed that was classified concerning a documented flight over Vietnam of A-12 Blackbird side #06931 (OXCART 128) of Mach 3.56 at 92,500 feet? That would put that A-12 going at 2,500+ mph at 17.5 miles up at altitude! We already know that the YF-12A Blackbird side #06936 flew its maximum speed of Mach 3.35 at 90,000 feet as well as it performed several World Absolute Speed records; 15/25 km straight course - 2,070.102 mph & 500 km closed circuit course - 1,643.042 mph & same day 1,000 km closed circuit course - 1,688.891 mph ..... all on May 1st, 1965. We also know that the XB-70 flew Mach 3.1. While we are talking record speeds...although I am not an SR-71 fan; it flew 2,193.2 mph at 85,069 feet on 28 July, 1974...however, many of the actual U.S.A.F. speed records, including the so called "Streak Eagle" flights were conducted with aircraft basically down! (Back seats removed, avionics removed, radars removed, etc.) Not with OXCART 128's flight...it was the "real deal" flying its mission with full gear!! Oh, I think I forgot the YF-12A flight on 21 Dec, 1966 where pilot Bill Parks covered 10,198 statute miles in 6 hours!! I hope that I didn't ruffle any feathers....I am a TRUE A-12 Blackbird fan, as well as a True XB-70 % YF-12 fan, too! I just thought I would throw my two cents into the fire.....
-Kerchan3
 
Kerchan3 said:
You are familiar with the World Record top speed that was classified concerning a documented flight over Vietnam of A-12 Blackbird side #06931 (OXCART 128) of Mach 3.56 at 92,500 feet?
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Source?

Kerchan3 said:
We already know that the YF-12A Blackbird side #06936 flew its maximum speed of Mach 3.35 at 90,000 feet as well as it performed several World Absolute Speed records;
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Source?

Kerchan3 said:
We also know that the XB-70 flew Mach 3.1.
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As I recall it was Mach 3.02.

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In 1990 I had a conversation with Ben Rich and in it he talked about the March 6 record-setting flight delivering 17972 to the Smithsonian. He said that since it would be its last flight, Lockheed suggested that the trip be made using a safe, but above normal operating speeds, profile. Apparently the difference would be notable. ,USAF (which didn't want the record flight to happen at all), firmly nixed that. Some years later in correspondence with COL. Richard Graham the topic of ultimate speed came up again. I asked him about certain flights wherein the elapsed time meant speeds way above M3.2-3.3. His answer: "Don't forget tailwinds".
 
F-14D said:
I asked him about certain flights wherein the elapsed time meant speeds way above M3.2-3.3.
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Mach number was never the limiting factor anyway, it was always CIT. Reading one of Col. Graham's books and seeing all of the "temp dev" and CIT stuff explained was really interesting.

What I want to know is if anyone ever figured out what booming the Hanoi Hilton with two SR-71s was all about...
 
SOC said:
F-14D said:
I asked him about certain flights wherein the elapsed time meant speeds way above M3.2-3.3.
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Mach number was never the limiting factor anyway, it was always CIT. Reading one of Col. Graham's books and seeing all of the "temp dev" and CIT stuff explained was really interesting.

What I want to know is if anyone ever figured out what booming the Hanoi Hilton with two SR-71s was all about...
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There was also the issue of the aircraft's shockwave. As the airspeed increased, its angle started translating aft. If the a/c went fast enough it would impinge on the wingtips which would have had "unfortunate" results. Temperature, though, would limit speed somewhat before that point was reached.

For years the story was it was to signal to the POWs that they weren't forgotten, but later it was rumored that it was to communicate something to them, whatever it might have been is still classified.
 
tacairnet.com

Blackbird’s Revenge

A while back, I came across a fantastic recollection from a former SR-71 pilot of the United States Air Force about his experience at an airshow in England in the 1980s. It’s just too good no…
tacairnet.com tacairnet.com

Blackbird washes protesters with afterburner pull up blast.
 
KwaZulu said:
tacairnet.com

Blackbird’s Revenge

A while back, I came across a fantastic recollection from a former SR-71 pilot of the United States Air Force about his experience at an airshow in England in the 1980s. It’s just too good no…
tacairnet.com tacairnet.com

Blackbird washes protesters with afterburner pull up blast.
Click to expand...
Interesting story, but hard to verify if true. I lived near Greenham Common at the time the SR71 visited for the International Air Tattoo (it was 1983, not 1985 as suggested in the link above, the IAT moved to Fairford from 1985). I was 14 in 1983, so at school at the time and remember the Blackbird's approach being visible from the classroom I was in on the day it arrived - it came around before landing so we saw the approach with gear down twice - it was not a productive lesson for the teacher!

The location of the peace camp was to the south of the base, at the main entrance, by a busy road and parallel to the main runway. In order to overfly the camp the SR71 would have had to take off, go around and fly low over the main road as well as the main entrance, meaning it likely that this spectacular departure would have had many witnesses and been reported in the local media. The hardened cruise missile shelters were also to the south edge of Greenham comon, to the east of the main entrance. This would have also meant getting permission to overfly close to the shelters. Like I said, not saying it didn't happen, but seems more likely to be a great story than reality. In the UK at this time the peace campaigners were major news, and run-ins between them and base securty/local police were regularly reported, so seems a long shot this wouldn't have been picked up in the media.
 

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