Mikoyan MiG-25 "FOXBAT"

Hi guys, dug out this old thread as the SR-71 propaganda has spiked once more recently....
I figure whatever the SR-71's top speed is, it was known only to the USAF (and probably the USSR pilots who happened to have tried to intercept one... and failed).
The SR had a modification with weapons bay or some other means to deliver something very big and nasty very fast very far. Irrepective if it was ever tested, installed, etc. This capability could have been exploited.
Technically there were proposals of the A-12 called the R-12, B-12/B-71, and RB-12/71. If I recall at least one of them could carry Polaris warhead.

Then from there came the RS-71 which was designed for reconnaissance strike: Effectively, the goal being to identify anything that happened to survive the first-strike and destroy it with nuclear weapons. For one reason or another, General LeMay felt like calling the plane SR for Strategic Reconnaissance, and asked President Johnson's speech-writer to alter RS-71 to SR-71.

While it required thousands of documents to be changed from RS-71 to SR-71 and, for one reason or another, the aircraft was never fitted/tested with the provision to launch such a weapon, it was felt the aircraft could be easily configured to do so. The chine-bays were modular and, in addition to mounting all sorts of sensors, could carry weapons. The weapon initially specified wasn't clear, it seemed to be some form of progenitor of the AGM-69 which appears to have been cancelled.

The AGM-69 had been later proposed as an option but was never fitted, though Lockheed's ADP had looked into the idea quite favorably (when launched from higher altitudes and speed, the missile would be able to go further on momentum).
The MiG was more than capable to intercept and down and SR with very high probability even alone.
Absolutely not, Lt. Belenko basically said that.

While, it might have been possible to coordinate an intercept from multiple angles whereby some missiles would be fired head-on, others from abeam, and some from the rear quarter, and basically make it highly difficult for an SR-71 to escape attack, I'm not sure how easy that would be do-able in practice.
At high supersonic speeds the airfoil doesn't work the way it does at lower speeds. Lift is created by the angle of attack.
Lift is created by alpha at low speeds too, the pressure differential is a lot lower (which combined with shockwave formation, produces considerably more drag) when supersonic than subsonic, and the center of pressure moves back to varying degrees, which tends to reduce elevator control available for maneuvering. As a basic rule of thumb, the g-load that could be pulled when supersonic is about half that of subsonic owing to this (as well as other variable such as airframe heating, depending on aircraft construction).
Also the burned engines myth is already busted, they didn't burn. See that video, you could disregard what you don't like, but there are some graphs of the power Vs drag, lift, etc. that can't be disregarded
Looking at the figures you presented around 3.5 could be carried out at higher latitudes and around 3.77 at lower latitudes.

I had already figured the top speed was probably around Mach 3.75 based on the fact that the nose was very long and the areas that had some high temperature aluminum construction (350 C limit) were either in front of the canopy frame or behind it, as well as the mach meter (it didn't read up to Mach 4, but instead read just up to Mach 3. When flying at 3.2 mach, it looked like it was at 0.2, so I figured it was above 3, but below 4).

I would guess the SR-71's speed was greatly higher than listed, the USSR made some estimates of the top-speed based on espionage, some guesswork, and got it wrong.
P.S. The current record holder of absolute maximum altitude and time to altitude to 25, 30, 35 and 37-something km is the MiG-31...
The MiG-31, despite using turbofans also had a mass-injection pre-compressor cooling system that would allow the temperatures to be pushed up higher than the MiG-25, while also allowing more thrust lower.
 
DIA documents regarding the 1976 defection of a Soviet MiG-25 Foxbat pilot Viktor Belenko to Japan. Provides some interesting insight into the MiG and what the pilot was told regarding performance.
 

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Its quite easy to estimate the Mig-25 and SR-71 theoretical top speeds. Mach cones are well known phenomena and you want the entire plane to be inside the cone or you risk creating hot spots. So just figure out the angle from the nose to the wing tip and see what Mach number that cone corresponds to.
 
DIA documents regarding the 1976 defection of a Soviet MiG-25 Foxbat pilot Viktor Belenko to Japan. Provides some interesting insight into the MiG and what the pilot was told regarding performance.
That great, thanks
 
I was thinking about something regarding the MiG-25's top-speed. There are some things about it that don't seem to add up...

For example the engines: The Tumansky R-15 -- It only has a pressure ratio of 4.75:1, and 5 compressor-stages and from what I remember a pretty high turbine temperature. I know the Russians didn't quite have the engine capability that we had, but I still find it hard to believe that with that kind of pressure ratio with most of their thrust no doubt coming off ram-compression and the engine's colossal afterburner that it would redline at only Mach 2.83, and burn out at Mach 3.2

The plane had a fuel that had a high-temperature flashpoint, which while not quite as high as the JP-7 used on the Blackbird, still higher than say JP-4. Other than the Blackbird, the only plane I can think of that utilized a high flashpoint fuel was the XB-70 Valkyrie, which used JP-6. It is officially stated to be a Mach 3 capable design, however they did wind-tunnel tests to Mach 4, and the chief-engineer of the project stated that the inlets could perform Mach 4 speed, and it's been acknowledged that the J-93 could achieve it as well.

Now I'm not necessarily saying the MiG-25 could do Mach 4. But I'm wondering if it's limit is 2.8/3.2 or a bit higher than that especially for quick bursts.

Of course I don't know why anyone would lie about it though. It's not like it's a new state of the art design and it's not even our design.


Kendra
It's not a matter of running out of thrust, it's a matter of exceeding allowed turbine inlet temperatures. Which can mean your turbine blades stretch and start rubbing on the inside of the housing, which then causes a very nasty titanium fire that burns the airframe in half.


Compelling information. Unfortunately, the speed listed is what we are TOLD was observed. I've also heard other claims of MiG-25's doing 3.4 Mach during possibly the same overflight, or during another Israel overflight.

Not to sound distrusting, but keep in mind what a person is told isn't always what's true. After all, the Blackbird's speed has never been declassified and many people still accept the figure that the plane can do Mach 3.2, maybe 3.6 tops (even despite the fact that the Blackbird uses a specific type of Titanium alloy that can go up to 1,200 C, is actively cooled and the J-58 without any mods can do Mach 4 -- not even requring a bleed-bypass system, engine-trim and derich, active cooling for the engine, metallurgy changes and extra air-cooling.)


Kendra Lesnick
The J58 as installed in the Blackbird is turbine inlet temperature limited. Depending on just how cold the air is, a Blackbird could go faster over winter Siberia than over summer Iraq or Libya.

The inlet spikes physically run out of travel at Mach 3.55 and unstart the engines, though. Also, at Mach 3.55 the nose shock cone will touch the ailerons and cause control issues.



Compton electrons would damage the electronics more than anything else. How about a neutron flux generating warhead to pre-detonate enemy re-entry warheads.? ;D
They won't pre-detonate, they'll just fizzle instead.



Hi guys, dug out this old thread as the SR-71 propaganda has spiked once more recently. Some answers were very helpful and informative, thanks!

I just want to add some considerations to the thread:

1. What do you expect to hear from highly trained and indoctrinated USAF pilots? Full disclosure of BVR tactics and parameters maybe? Any trained military will give you the answer your question suggests, will say he doesn't know, or something random.
2. What do you expect to hear from a member of the Russian VKS?
3. What was the purpose of the MiG-25 after all? When seemingly SU-15, MiG-23 and even MiG-21 could do thye same job. They built more than a thausand of that extreme machine.
4. Why do some of you assume the USSR accounted for every modification they made or even for the actual parameters of an extreme and expensive weapons system that they built in big numbers - obviously relying on it for performing of some not really clear tasks. At that level of performance it should be intuitive that those extreme machines had parameters and flight envelopes dictating very specific way of piloting and missions profiles. - applies for both SR and MiG. Why would anyone disclose the actual parameters, profile, envelope, etc?
Intercepting B-70s was the original design intent. Then intercepting B52s and occasionally Blackbirds. MiG-31s added a look-down/shoot-down radar for dealing with cruise missiles.


P.S. The current record holder of absolute maximum altitude and time to altitude to 25, 30, 35 and 37-something km is the MiG-31... Figure it out by yourself. The MiG-25 is lighter and has more thrust at high altitude... Anyway, that's not that interesting, because in the high speed intercept game, time of takeoff has bigger influence on the chances than an altitude and speed drag race... that the MiG would have won...
Except that you need to get the aircraft into position to shoot a missile. The SR-71s "radar warning" response was to accelerate and turn. At Mach 3.whatever, each minute is 37 nautical miles. Yes, interceptors were somewhat more likely to succeed than fixed missiles (short of the SA-5 Galosh nukes around Moscow). But it's still an impossibly tiny point where the aircraft is in place to get within a couple miles of the ground track of a Blackbird and then also be there in time to get into proper flight parameters to launch a missile.

Completely ignoring the ECM systems fitted to the Blackbird, of course.



Its quite easy to estimate the Mig-25 and SR-71 theoretical top speeds. Mach cones are well known phenomena and you want the entire plane to be inside the cone or you risk creating hot spots. So just figure out the angle from the nose to the wing tip and see what Mach number that cone corresponds to.
Yup. Mach 3.55 or right around there for the Blackbird.
 
The maximum Mach-number of the aircraft with and without the stabilizer differential control system is limited with respect to thermal strength of the engines and it amounts to 2.83.

For the same reason, the flight endurance at Mach-numbers exceeding 2.4 equals 15 min (at Mach-numbers M = 2.65 it amounts to 5 min). The flight time at Mach-numbers of M = 2.4 and less is not limited.

[...]

The service ceiling of the aircraft carrying four missiles under standard atmospheric conditions is 20.500m.

In this case, the aircraft mass at the service ceiling equals 25,800 kg and the remaining fuel amounts to 3500 kg. The average time of gaining an altitude of 20,000 m at M = 2.35 in standard atmosphere conditions, with the engines running at FULL REHEAT (ПОЛНЫЙ ФОРСАЖ), from the moment the take off run is started is equal to 9.7 min for the aircraft carrying four missiles .

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The maximum Mach-number of the aircraft with and without the stabilizer differential control system is limited with respect to thermal strength of the engines and it amounts to 2.83.
I rest my case.
 

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