When I see this, I can only think of modern high-altitude balloons. My gut tells me the SR-71 would be an ideal interceptor for that new threat (despite not being an interceptor itself).

The balloon issue cannot be addressed by any modern US aircraft, and spending expensive missiles on low cost balloons seems like wasting money and resources.

We'll know soon.

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nradov 3 hours ago | parent | next [-]

The SR-71 was never designed as an interceptor, and would require extensive modifications to carry and employ weapons. Not going to happen. There was an earlier YF-12 interceptor program but it never proceeded beyond the prototype stage.

High-altitude balloons are hardly a new threat. They have been used for decades, although some recent Chinese models are more capable than before. Regular tactical aircraft already in the US inventory are perfectly capable of shooting them down.

https://www.af.mil/News/Article-Display/Article/3288579/f-22...

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gaigalas 2 hours ago | parent [-]

Current aircraft is not capable of reaching those balloons, read my other commentary. Your link points to a Chinese balloon that dropped way below its operational range.

SR-71 or not, there are already contracts for filling this niche:

https://www.war.gov/News/Contracts/Contract/Article/4613098/... (search for "swamp gas").

If money is flowing to counter/develop high-altitude balloons and declared as urgent, it's likely it's flowing in more than one vein.

The frame modifications you mentioned are already specified and tested, part of the YF-12 programme. It can easily carry air-to-air missiles instead of reconnaissance equipment, and the frame has flown with that configuration.

https://en.wikipedia.org/wiki/Lockheed_YF-12

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nradov 2 hours ago | parent | next [-]

AIM-120 range and altitude upgrades have been in the works for many years, and balloon defense is a relatively low priority mission. It will also be supplemented by the new AIM-260 which has greater capabilities. The primary goal of those programs is to achieve greater stand-off range versus near-peer adversary aircraft.

The YF-12 prototypes looked superficially similar to the SR-71 but had substantially different airframes. There is simply no place in an SR-71 to mount the necessary weapons, sensors, and avionics without completely rebuilding the entire aircraft. That would be a stupid waste of resources when existing platforms can already accomplish the mission well enough.

	▲	gaigalas 2 hours ago \| parent [-]
		What are you talking about? The YF-12C was a converted SR-71. It flew exactly as I'm describing. All of this has already been done before. You might be confusing the YF-12 with the A-12, which is related but a significantly different airframe. I won't engage in discussing whether balloons are high priority or not. Let the 2023 events and the funding towards those areas speak for themselves.

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walrus01 an hour ago | parent | prev [-]

> Current aircraft is not capable of reaching those balloons

Is a missile a form of aircraft? Because there's variants of the Standard Missile which can hit a low earth orbit satellite, with the right timing, fired from effectively zero velocity and at sea level from a frigate.

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gaigalas an hour ago | parent [-]

Well, it's not reusable. You're wasting a resource destined for hypersonic deterrence on some sheets of mylar that float around.

I mean, you can do that, but it would be a tremendous embarrassment.

	▲	walrus01 an hour ago \| parent [-]
		> Well, it's not reusable No it's not. And it's indeed very costly. But on the grand scale of things of what the US DoD spends per day as a fully loaded lifetime cost to operate a single SSN, SSBN or aircraft carrier, it's a drop in the bucket. They spend absurd amounts of funds on all sorts of things.

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bigyabai 4 hours ago | parent | prev [-]

The service ceiling of the SR-71 is still well beneath the altitude of a modern balloon. The speed isn't necessary, and it's altitude record has been beaten by other modern jets.

If we're spitballing solutions, balloons are slow, fragile and move in relatively predictable paths. An F-15 could reach the same altitude, and launch it's own balloon with a small solid-fuel booster that also corrects the trajectory. If the interceptor balloon could get within 1-2km of the target balloon, then a cheap kinetic weapon firing HEI projectiles might be enough to destroy it.

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gaigalas 3 hours ago | parent [-]

The F-15 can climb 30,000 feet.

https://en.wikipedia.org/wiki/McDonnell_Douglas_F-15_Eagle

That is the lower bound of what modern high-altitude balloons can reach. Back in 2023 multiple balloons were observed much higher than that up to 50,000 feet.

https://en.wikipedia.org/wiki/List_of_high-altitude_object_e...

This is still in the lower spectrum for such balloons. BS 13-08 reached 176,000 feet back in 2013 (there is reason to believe spy balloons would not go that high though).

https://en.wikipedia.org/wiki/High-altitude_balloon

So, you're wrong. There is no US aircraft that can reach them (unless they drop low as they did in 2023). The US likely wants to hit them before they go low.

The SR-71 is uniquely suited for this task, having reached up to 90,000 feet during testing. It was specially made for some kind of hybrid space war possibility (not balloons, but something high up there).

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somat 2 hours ago | parent | next [-]

Your amounts are off. that wikipedia page lists the f-15 as having a service ceiling of 65,000 feet. Perhaps irrelevant but a f-15 shot a satellite down once(not relevant because that is more the missiles capabilities than the planes, which is probably the relevant point)

Unit mix up?

The f-16 however, does have a surprisingly low ceiling, there are fighter pilot memes about it. https://www.youtube.com/watch?v=koEQp8ImlnI?t=643 something about having small wings, get above 30,000 feet and it's not happy.

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bigyabai 2 hours ago | parent | prev | next [-]

You misread your source: the F-15 can climb 30,000 feet in 60 seconds - the service ceiling is closer to 60,000 feet officially, and 90,000 under ideal conditions:

https://theaviationgeekclub.com/how-the-f-15-streak-eagle-br...

By "same altitude" I was referring to the SR-71. I do not know what the payload capacity was for either aircraft in the 90,000ft testing conditions, but for interception missions there are more important metrics.

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lelandbatey 2 hours ago | parent | prev [-]

Per the first link you provided, the F-15 has the following:

Service ceiling: 65,000 ft (20,000 m)

That's high enough to go 15k feet above the highest ballon mentioned in the second link you provided, which was 50,000 feet.

Also, the SR-71 carried no weapons, only cameras, and re-tooling to support them would be far more expensive than merely shooting a balloon with a missile from the ground (or building an air-to-air missile that can be fired from existing platforms at altitudes like 65k feet).

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gaigalas 2 hours ago | parent [-]

Fair correction on the altitude (still in the lower bounds of the balloons, as I mentioned).

The SR-71 already flew in the configuration I mentioned. It's the YF-12C (a converted SR-71).

Recovering and converting another sure is more expensive than one missile, but it's a reusable platform.

A ground missile able to reach those balloons is more expensive than a modernized SR-71 sortie. High-altitude, precision missiles are also not allocated for this task. China can launch dozens of balloons for cheap, and spending one multi-million-dollar missile on each is insanity. Even the long range air-to-air ones are too expensive for that.

The SR-71 (as a new YF-12D interceptor) makes more sense. It can take multiple balloons in one flight with cheap shorter range air-to-air missiles (or maybe even cheaper weapons, for a balloon a laser would do), then go home and do that over and over again.

	▲	bigyabai 2 hours ago \| parent [-]
		China can launch a lot more than a dozen balloons, perhaps thousands if convincing decoy payloads can be made. The A-12 was intended to counter high-value targets in a limited number, not low-value targets en-masse. I can't rule out that Issacman does have this mission profile in mind, but it seems contrived. Whatever weapon the SR-71 could carry to-altitude could be be done cheaper, more numerously and probably more quickly too with F-15s. Refurbishing a fleet of SR-71s and a fleet of KC-135Qs would be a lot of work for an extremely limited capability.