MiG-31: The Near-Space Plane. Russia’s super-fast interceptor - Page 3

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[ARCHIVED THREAD] - MiG-31: The Near-Space Plane. Russia’s super-fast interceptor (Page 3 of 3)

Posted: 10/8/2018 9:30:05 PM EDT

[#1]

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With the proper missile tech it is possible. We tested a F-15 launched anti sat missile decades ago. F-15 went vertical as far as it could before launch. Think we have better ways to smoke sats now though.

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The narrator kept talking about all the G-forces from flying so fast and high. Flying fast and high do not produce Gs, turning or accelerating does. Then he directly conflates vibrations with G-forces

. He had no idea what he was talking about, and neither did the writer.

Some of the guys also say that the plane can shoot down satellites. Hmm, let's do the math.

MiG-31
Max speed 3,000kph
Max height 25,000m

Satellite
Average speed ~25,000kph
Average height 200,000m

A satellite is more than eight times faster and eight times higher.

With the proper missile tech it is possible. We tested a F-15 launched anti sat missile decades ago. F-15 went vertical as far as it could before launch. Think we have better ways to smoke sats now though.

I was in the squadron that got that assignment and flew the sim profiles.

There was a very small launch window. The profile was not straight up, the profile was arriving at high mach number, altitude, geo box, and attitude nose high which was no where near straight up at a very specific time.. High speed was critical, actually it was all critical.

Posted: 10/8/2018 9:53:58 PM EDT

[#2]

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When I was a kid 25 years ago, it's maximum speed was Mach 3. Very vaguely Mach 3.

It's gotten 10% faster in 25 years, but the point about it not having a speed limit, but a temperature limit is very interesting.

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No. It will still be some time IMHO before the true top speed and ceiling of the SR-71 are declassified.

It's not really a secret - around Mach 3.43 and in excess of 90,000 feet. However, if you would like to use the engines again, best keep it under Mach 3.3.

< 90,000 for 1g flight

IMHO excess of 90,000 feet sounds a bit vague. Also most of the specs I read said excess of 80,000 feet. So right there it's gained 10,000 ft in ceiling.

When I was a kid 25 years ago, it's maximum speed was Mach 3. Very vaguely Mach 3.

It's gotten 10% faster in 25 years, but the point about it not having a speed limit, but a temperature limit is very interesting.

That's pretty much the case for any supersonic airplane, especially near or over Mach 2. Not just temperature, but dwell time, although some piece of equipment might set the dwell limit. Anyway, look to the transparencies first.

As for the metal structure, we're extremely conservative in my opinion. We almost never have a good measure of the actual temperatures in flight, and calculated temps are as always, idealized no matter how complicated the equations.

Temperature cycles on the metal structure are also a concern sometimes, and depending on the alloy. The knockdown on room temp static properties can be calculated from a method in the 7075 section of MIL-HDBK-5 (MMPDS these days), but it's pretty snakey and worse when extrapolated to other alloys.

Posted: 10/8/2018 10:11:06 PM EDT

[#3]

@mach what are your thoughts on:

Mig-31

Su-27 (and family)

Posted: 10/8/2018 10:55:36 PM EDT

[#4]

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Did the SR71 actually overfly any of the Soviet Union?

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Only us and the former Soviet Union know. Egypt, Libya, North Korea, North Vietnam, Cuba probably had over-flights of either the SR-71 or its predecessor, the A-12. Soviet Union, Red China? Maybe ....

Posted: 10/8/2018 10:59:36 PM EDT

[#5]

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That's pretty much the case for any supersonic airplane, especially near or over Mach 2. Not just temperature, but dwell time, although some piece of equipment might set the dwell limit. Anyway, look to the transparencies first.

As for the metal structure, we're extremely conservative in my opinion. We almost never have a good measure of the actual temperatures in flight, and calculated temps are as always, idealized no matter how complicated the equations.

Temperature cycles on the metal structure are also a concern sometimes, and depending on the alloy. The knockdown on room temp static properties can be calculated from a method in the 7075 section of MIL-HDBK-5 (MMPDS these days), but it's pretty snakey and worse when extrapolated to other alloys.

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Compressor inlet tempts and the canopy material seem to be limiting factors right now. F-15 has the power to go faster, but would need a different canopy material that wouldn't melt from friction. Mig-25/31 apparently use water/alcohol injection to try to keep the temps low enough at the compressor inlet that the turbine blades don't crystalize when they cool back down.

Posted: 10/9/2018 8:20:10 AM EDT

[#6]

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@mach what are your thoughts on:

Mig-31

Su-27 (and family)

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Mig-31 is an old ( 4 decades old ) high fast interceptor designed to shoot down large bombers. It is not a capable fighter. Like all soviet designs of the time, it was designed and built with brute force and it does well at what it was designed to do, go high and fast. But it is not a tactical fighter. I have no idea if the weapons packages and avionics have been upgraded in the last 40 years.

The SU-27 is a capable but outclassed fighter in comparison to the F15 of the mid 1990s. The F15 has been significantly upgraded in capability. I don't know if the SU-27 has been upgraded ( I suspect it has been to some extent), but at the time there was no contest unless the eagle guy had significant degradation of systems or had his head up his ass.

When I was in the difference in technology and capability in a complex environment was extreme.

And the always unique compounding force multiplying difference is in the training and the tactics

There are reasons why the F15 and the F22 remain virtually unchallenged in close to 40 years in establishing air superiority and air dominance.

The F22 without a doubt would be like clubbing baby seals compared to the SU-27, because the F22 is like clubbing baby seals against the F15, from what I have heard.

Disclaimer: I have been out for 20 years. 5 years is a long time in the air to air world, 20 years is like an outdated history book.