SR-72 ‘Son Of Blackbird’ | Hacker News Reader

SR-72 ‘Son Of Blackbird’

19fortyfive.com

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That airframe, while super super intriguing, isn't a hypersonic airframe style.

It's most likely something for NGAD [1] purposes.

1. https://www.nationaldefensemagazine.org/articles/2021/9/21/a...

Off-topic: what a terrible mobile experience. You have to dig for the content between all the BS ads.

On Android, I highly recommend Firefox with the ublock origin extension.

On apple mobile devices, I bought "Adguard pro" which seems to work pretty well.

1blocker is good as well on apple devices.

Zero ads here in iOS with FF.

Same using Brave

Somewhat on-topic, have there been any updates from Skylon or SABRE engines lately? Single stage to orbit seems so sci-fi I wonder if we'll ever get close.

Maybe someone here happens to have a link to the video by the US pilot who was shot down in Vietnam and severely injured, told he would never fly again, and yet became a Blackbird pilot. Fun stories about flying it.

It's long, but well worth it, I promise. I'm not sure if this [1] is the one I'm thinking of, but it's the same guy anyway.

[1] https://www.youtube.com/watch?v=Ndamj_Ewod8

If it can carry armaments, who will tolerate it as an intelligence gathering plane? And how can one know what its mission is in real time?

To not tolerate it, you need something fast enough to shoot it down.

Incorrect, you shoot down something else afterwards.

That's generally not how these things work. Shooting down a plane that you feel invaded your territory is one thing; shooting down something else makes you the aggressor.

This was well established with U-2 and SR-71 flights in the cold war.

Sending the U-2 or SR-71 is like sending spies. Something most countries do and so expect and tolerate of others.

The SR-72 has strike capability. It's more like sending an assassin or rolling a tank into a foreign country. That's an act of war.

Unless it actually strikes, no country is going to escalate an overflight to a different hot strike. Air powers regularly fly along the borders and intrude and have for the last 70 years. Overflights were deemed acts of war during the cold war as well - that's why the USSR tried to shoot down all of the U-2 planes they could (ultimately succeeding on Gary Powers' flight) and any other things they considered spy flights (such as the KAL-007 crisis). At no point did they escalate in other areas. War is hell, and countries go to great lengths to avoid it - even when they're angry.

> no country is going to escalate an overflight

The USA is not going to escalate if Chinese or Russian aircraft start flying over Washington or NYC with impunity?

Don't be naïve.

Which many countries have. S-400 is designed to hit targets going at Mach 14.

The question is, of course, for which mission profile you even need a manned and/or large plane like this.

Will this be autonomous? Will it be superseded by loitering munitions, drones and super fast rockets?

Another nitpick: > similar size and range as the SR-71 and will likely engage in the same missions.

The SR-71 was an espionage plane, not an armed one as far as I know.

Technically the YF-12 was armed.

The article states that it's unmanned and emphasises intelligence capabilities.

I thought SR-71 had some strike capabilities, but I could be mistaken.

Thanks, you're right.

That raises the interesting question of how large, hypersonic UAVs are expected to be used.

What kind of intelligence mission benefits from a fast flyby but cannot be performed by a satellite?

What kind of attack is fast but cannot be from a guided weapon?

Maybe geolocating cell phones or WiFi?

“ What kind of intelligence mission benefits from a fast flyby but cannot be performed by a satellite?”

Perhaps they expect the spy satellites to be immediately blown up in this conflict.

All you have to do is lase them.

Like handling security cameras... you can fire an artillery shell at a security camera, but most of the time security cameras are mission ineffective if you just shine a bright enough flashlight (or laser) at them.

There's no need to cause an international incident by blowing something up when all you need is a bright light for a couple easily predictable minutes.

On the other hand a stealthy hypersonic flyby is probably invisible.

Another military aspect civilians never want to talk about is photo analysis depends on illumination and rando satellite passes can't see into valleys and get messed up if the shadows are weird enough. Just because technically a satellite passed within range of Afghanistan as a whole country, doesn't mean you can see what's happening on the wrong side of a mountain with bad illumination and bad view angle. There's a lot of satellites but not THAT many. Afghanistan used to have boots on ground to launch UAVs but not so much anymore.

There are a limited number of spy satellites, and their orbits are fairly fixed. If you need to look at a site you have to wait until a satellite passes it (and the people at the site will be able to know quite far in advance when a satellite is coming). And there's no way to delay the pass until the cloud cover clears.

You could potentially hide a satellite from radar observation the same way you can for planes. That's apparently what the Misty program [1] did. Synthetic aperture radar could take care of clouds, though you lose color. Agreed about maneuverability I think.

1. https://en.wikipedia.org/wiki/Misty_(satellite)

They probably won’t send in U-2 or MQ-9 to stick ninja swords through the roof of a luxury sedan past rings of S-300 SAM batteries few hundred miles from shores.

Are you referring to the Hellfire R9X "flying ginsu"?

What kind of intelligence mission benefits from a fast flyby but cannot be performed by a satellite?

The orbits of satellites are known. The target can arrange activities to occur when there is not a satellite overhead. A fast flyby can occur at any time with little or no warning.

Satellites were great during the cold war when the targets were consistent, and the satellites could be put in orbits with good coverage of those areas (eg Russian military bases). Spy planes like the SR71 and U2 that fly high and fast to evade detection or destruction are essential for getting immediate photos of an area that may not have regular satellite coverage.

You may be thinking of the YF-12, which was based off the closely-related-but-not-the-same-at-all A-12 precursor to the SR-71.

Brag: I've actually seen a YF-12, up close, at Edwards AFB. NASA used them for testing for many years.

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

> The SR-71 was an espionage plane, not an armed one as far as I know.

That would be the YF-12, a prototype interceptor built off of the A-12, the A-12 being the base from which SR-71 was also derived.

Having family and friends deep in the industry, and a dad, grandfather, uncle and grandmother who worked at Lockheed and specifically the Skunk Works - this is not real. This stuff gets made up all the time.

The real stuff being done at the Skunk Works is not stuff you will ever ever hear about.

Congratulations on an interesting family then!

I guess the public will eventually learn some things. Personally, I'm not so much concerned about technology that I don't see as much as about technology that is cheap and effective enough to be out there: remote controlled sniper rifles, bomb-dropping drones, chemical weapons.

I don’t know the good stuff either. I know stuff that’s been unclassified but everything else is a mystery to me as well. My family has great stories but they are also committed to the integrity of the mission.

Have you read the article about how Israel remotely assassinated an Iranian nuclear scientist? [1]

Not a sniper rifle but remotely controlled and AI assisted. It was right out of a movie.

[1] https://www.nytimes.com/2021/09/18/world/middleeast/iran-nuc...

Yes that's what I was referring to.

It seems we are catching up to some scifi fast. Let's hope it's not the Daniel Suarez version.

That's what I would say too if in fact all I had was an Iranian cooperative, or Israelis on the ground.

my uncle works at nintendo and he confirms its real

We know the US is working on hypersonic weapons. It makes a lot of sense to put that same technology in a reusable UAS. This doesn't seem like such a stretch as to be instantly dismissed. I would take reports about it with a grain of salt, and the SR-72 designation is there to grab headlines, either from the news source or Lockheed Martin, but it's very feasible for them to be building the thing described in the article.

You are correct. Hypersonic, autonomous aircraft and weapons? Yes. Will it be the SR-72? No.

So is your problem the designation, or the actual concept that is being developed? Because, frankly, who cares what it's called. The important thing is what it can do.

My problem is with neither - it’s with the way the aviation community will jump on theories and build them up into big snowballs that are usually not even remotely close to reality or might even be talking about an aircraft that simply doesn’t exist.

So I don’t get stoked about news headlines like this because generally it’s just fun masturbatory stuff that doesn’t hold a lot of truth in the real world.

A release like this has to be a chess move or entirely made up. You don’t just share weapons platform plans for no reason. You underpromise, overpromise, lie, brag, or misdirect in order to achieve some outcome.

You see it and ask yourself “why?” and “how much is BS?”

To explain all the UFO hoopla

I guess that /s may be optional???

I agree though. Things like this dont come out of SKunkworks before they are operational.....or sometimes even after for that matter.

By hypersonic weapons, do you mean missiles? Are they even useful? To follow the curvature of the earth, they have fly higher than a subsonic cruise missile, making them fairly easy to spot. Not sure how hard they are to shoot down.

> Not sure how hard they are to shoot down.

Judging from anti-ballistic missile efforts, quite hard.

>Are they even useful?

Potentially, yes. For example, for the same reasons you list, they are capable of being used in space-defense, like anti-satellite or ballistic defense.

Something going mach 5+ is going to be extremely difficult to shoot down. Typically, they boost up to high altitudes then come back down to lower altitudes to actually strike the target (boost glide). Looks like the air force is also developing a cruise missile which would fly at lower altitudes.

It's not that hard to hit something going Mach 5 or so at high altitude. That translates to speeds of just over 5000km/h.

The really hard thing is to hit targets that go close to orbital velocity (for example when trying to hit a hypersonic missile going 11 000km/h+ or a ballistic missile going 20 000km/h.

Flying very high and very fast poses timing challenges, in order to shoot it down you have to see it, make the decision to shoot it down, and then have an interceptor which is fast enough to make up for the detection lag, get to altitude, and get to location.

For something that could cross the continental US in a half hour or less, you can imagine there is not a lot of room for delay.

Modern SAM systems are made to launch in less than 15 seconds after detection. Their missiles go 2km/s+, and they are made to detect targets from 400km+ away. The SR-72 would not be the most difficult target they are built to engage.

> Are they even useful?

Being able to see or attack something thousands of miles away within the hour is very useful.

We've heard of at least:

P-38, P-80, U-2, SR-71 (etc), F-117, F-22, and F-35

have they stopped making things we will hear about?

> The SR-71 was an espionage plane, not an armed one as far as I know.

And a very fast one.

https://theaviationgeekclub.com/sr-71-blackbird-pilot-tells-...

Probably be used to deal with nuclear TELs and people on backseats in sedans? YF-12 and M-21 variants of A-12 had bays and launchers but none of Blackbirds had necessary cameras for air to ground weapons.

The yf-12 was a fighter version of the SR-71 cancelled during the Vietnam war.

Missile launch platforms greatly benefit from high speed and high altitude. A hypothetical Mach 6 aircraft at 100k feet will likely have at least double the A2A missile range of an F-16 at 30k ft launching the same missile . Given that most long range A2A missiles peak at Mach 5 it would be extremely difficult to engage such a platform.

Not just A2A. There were studies done on arming SR-71s with SRAMs in the chines — both downrange and crossrange performance was massively improved.

https://lh3.googleusercontent.com/proxy/EmV9xz0SUL1NW08RDs3Z...

You missed the opening:

The Lockheed Martin SR-72, also known as the “Son of Blackbird,” is a hypersonic unmanned aerial vehicle

btw, the Blackbirds are in lots of museums. I've visited one in Tucson and another in Seattle.

I thought the true top speed of the SR-71 is either highly classified or truly “unknown”.

How does the article justify saying the 72 will be roughly 2x the speed of the 71?

It was seen by Soviet pilots and radar (it was poorly visible but not invisible). As to top speed, from what I've heard that's a matter of how much wear and tear you're willing to incur.

So in theory, could be Mach 4-6 already in an SR-71?

If the SF71 was like many other military aircraft, then it could be flown far beyond the long-life envelope. Overclocked, if you will, getting extreme performance for an hour at a cost of years' wear on the engine and body. You can see how this approach might make sense for an SR-71 where one might sensibly want to sacrifice the aircraft to get some pictures out. You can also see how this complicates defining "top speed".

You don't have to know the actual speed to say, "whatever the (classified) speed was, we will double it".

X * 2 = (Mach) 7

That’s the formula expressed by the article, is it not?

Ah I missed that - you are correct.

It depends on your definition of "top speed": on the Blackbird and other supersonic aircraft, higher speeds mean higher temperatures. It's possible to sprint for a short time and absorb some of the excess heat, but have a lower limit for continuous operation. The shorter the duration, the higher the speed.

There is very big, fundamental problem of flying at mach 4+ anywhere in the atmosphere: heat from aerodynamic friction > heat dissipated.

All, and everything that flew so fast before relied on evaporative cooling, and under the evaporate, I mean the solid parts of the spacecraft/airplane/missile.

For a reusable craft, it will mean big disposable heat shields.

The Blackbird used fuel as a heat sink. This sounds like something affected by scaling laws, such that a larger craft would have more mass available for heat absorption.

Yes, fuel as coolant worked at around mach 3, but at mach 4+ the kerosene itself may not not be energetic enough to both sink heat, and produce more energy than the energy of incoming airflow.

Supercooling the fuel may work to some extend.

Having the entire aircraft being a flying liquid hydrogen tank is another least improbable option.

I suppose heat flux is still a limiting factor that's independent of scale. Though things like liquid evaporative cooling (by "sweating") also become more practical with larger scale (more mass available). Not sure how big it would have to be though...

> Yes, fuel as coolant worked at around mach 3, but at mach 4+ the kerosene itself may not not be energetic enough to both sink heat, and produce more energy than the energy of incoming airflow.

The blackbird did not use kerosene, it used JP7, specially designed for high range of operation as well as being usable for cooling and hydraulics.

> JP-7 is unusual in that it is not a conventional distillate fuel, but is created from special blending stocks in order to have very low (<3%) concentration of highly volatile components like benzene or toluene, and almost no sulfur, oxygen, and nitrogen impurities.

JP-7 is famously hard to ignite, the blackbird needed TEB shots to start ignition, and was initially started by driving the engines with a starter cart composed of paired V8s (later replaced with a smaller and simpler compressed-air starter).

The Waverider used the same fuel, and fuel-cooling, and reached Mach 5.1.

> The Waverider used the same fuel, and fuel-cooling, and reached Mach 5.1.

Not so much as coolant, but as a thermal mass reservoir, and only for a few minutes.

It also had body panels that had gaps at ordinary temperature (and leaked fuel), and the gap closed as the metal expanded with heat. Also, the US did not have enough titanium production capacity so bought it from the USSR using shell companies...

Not the body panels, the fuel piping.

You seem to be ignoring the space shuttle entirely, which handled the heat of re-entry at 17,000 mph and was still reusable. You have to make trade-offs on weight and materials (like heat tiles), but it's not impossible.

The Space Shuttle wasn't reusable in any meaningful sense. It required a complete overhaul after every mission, including replacement of many damaged ceramic heat shield tiles. And it only flew at hypersonic speeds for a few minutes during re-entry.

Space Shuttle used expendable ablation, thermal barrier materials, and thermal mass of its structure.

All of that was only to last for a few minutes of re-entry, not constant flight in such conditions.

I'm sorry, but you are either misinformed or we're talking about different things. The HRSI tiles on the shuttle were not ablative, were absolutely reused multiple times, and there's no indication that they couldn't withstand high temperatures for long durations. They were largely inspected and replaced due to impact damage from micrometeorites and ice, not due to thermal ablation.

The biggest issues with the shuttle's thermal management approach are that it used an aluminum airframe and the tiles alone wouldn't be suitable for the leading edges of an atmospheric air breathing plane due to the higher dynamic pressures and probably higher heat involved. At mach 4 temps they would be fine. At mach 6+ you'd need something better on the leading edges combined with a temperature-resistant airframe. There's a good paper on the topic here [1].

[1] https://ntrs.nasa.gov/api/citations/20080017096/downloads/20...

Thermal barriers will slowdown the rate at which heat gets into the aircraft, but it cannot keep it out it forever.

Yes... That's exactly what I said in the second paragraph. Not sure what your point is.

Ablative heat shields are reflective, not evaporative though. They generate a thin gas layer that reflects the heat from the compression wave.

It's accepted that the top speed of the SR-71 was likely around Mach 3.5. The Mach 3 records were just for show, and pilots have said that even at Mach 3 when they pushed the throttle forward, it just went.

This article also says that the SR-72 will use "a dual-mode engine that combines turbine and ramjet technologies." The SR-71 already did that.

> It's accepted that the top speed of the SR-71 was likely around Mach 3.5. The Mach 3 records were just for show, and pilots have said that even at Mach 3 when they pushed the throttle forward, it just went.

FWIW the official record is Mach 3.3, Air & Space/Smithsonian reported that it'd been clocked at 3.4 by USAF, and Brian Schul claimed to have exceeded 3.5 during evasive manoeuvres. Mach 3 was never claimed to be anywhere its limits. Hell, the design / cruise speed was 3.2.

I was generalizing, but your point backs mine up all the same. Thanks :)

There was a declassified manuals for one of Blackbird models from few years ago, and it wasn’t inconsistent with Mach 3.75 top speeds. Maybe they do 3.6669999 or 3.78925 but can’t be like it could go all the way to 22 flat out in a straight line.

A couple comments on supersonic aircraft:

There are no jet engines ever made that I'm aware of that can run at supersonic speeds. The fastest mass air flow rate I've ever personally heard of was some Soviet thing that didn't immediately self destruct around mach 0.98. The way supersonic aircraft generate thrust while supersonic is the inlet geometry does WEIRD things to turn supersonic cold low pressure air into low subsonic hot higher pressure air. Most jet engines are happiest with inlet air flowing around 200 to 400 mph. If you run a jet engine above some critical subsonic speed occasionally shock waves will impact the compressor and every time the compressor rotates the blades will hit those shockwaves, and they rotate pretty fast... So the MTBF for a SR71 compressor blade might be 100000 hours at a nice subsonic mach 3.25 but whack it with supersonic shock waves every rotation and at mach 3.5 the MTBF for a compressor blade might be one hour. The nozzles in front of the engine fully retract at mach 3.25 and I'd interpret that as the inlet system is not designed to run "much above mach 3.25". There's a story about a flight over Libya where the pilot pushed a SR71 to mach 3.5 and that engine was likely pulled and sent to scrap yard after that stunt.

The other side of the problem with inlet geometry is the inlet temp gets very hot so you have to go ramjet to get most of the thrust because trying to generate significant thrust will melt the turbine blades off. So hypothetically if you got 10K pounds of thrust by increasing the temp of the air by 1500 degrees and the inlet was dumping 800 degree air at mach 3.25 into the engine, the combined exhaust temp would be 800+1500=2300 degrees which is getting hot for turbine blades (all numbers made up). So the second engineering limit on why the SR71 never flew at mach 9 or whatever is based on public engine designs and the temperature of mach 9 air when slowed to subsonic, there are no metals you can make a turbine out of. In fact at mach 6 or whatever its kinda mysterious how they keep the ramjet from melting itself. Must look like a rocket engine with cooling passages for fuel everywhere. So based on the published engine design (and is the published data trustworthy?) there's no way to bypass enough air to not melt the blades off the turbine above mach 3.something because nobody has high enough melting point metals. As with the compressor situation I'm sure a 3.25 rated turbine blade that has a MTBF of 100000 hours might survive an hour or two at 3.5, but the engine is scrap after that flight.

The third supersonic comment is mach number is not constant with altitude so a pessimist person could say a mach 6 that flys high enough could very well indeed have a slower groundspeed than a sr-71 or even a 747. If the speed of sound at 120Kft is like 190 knots, then mach 6 at 120Kft would be a ground speed of merely 1140 knots. Famously the SR-71 could achieve ground speeds of 1800+ knots (supposedly...). So its simultaneously true that a SR72 might run twice the mach number but if it runs at a high enough altitude like my 120Kft example, its possibly only 2/3 the ground speed of a SR-71. The flight envelope of the SR-71 from the declassified manual is available; note it could not run supersonic below 20Kfeet or so. This also comes up in discussion of interceptor missiles; there's a huge difference in speed between a plane that can't go supersonic below 20Kft and a SA missile that can go mach 5 or whatever at ground level right off the rail. So its not as simple as "a mach 4 surface to air missile can never hit a mach 6 airplane" because mach 6 at 120Kft is much slower than mach 4 at ground level.

Scramjet engines can combust the air at supersonic speeds. Rumors are that the Chinese and Russians flew scramjet aircraft multiple times.

https://duckduckgo.com/?q=reaction+engines+sabre+precooler

From the article, it's unclear to me that this plane exists or will ever ever exist in a practical form, for that matter I don't think it's a given that reusable practical scramjet engines will ever make sense.

How do the intelligence gathering capabilities of the SR-72 compare against that or the various reconnaissance satellites? Why do they need this plane, if they can get comparable information from space?

One of the main advantages of the plane is ease of refueling. You either have to wait for a satellite pass or maneuver the satellite which eats into its very limited fuel.

The information may be comparable but the latency is not.

Think of it like playing CoD on satellite internet vs fibre.

The sr72 has 2 advantages over satellites.

1) satellites are very predictable, so it's possible to hide things from them.

2) satellites are very very far away, so the sr72 can get better pictures by dint of being closer.

This article touches on both examples where satellites were predicted and planned around and some discussion of satellite imagery limitations: https://www.npr.org/2019/09/05/758038714/can-president-trump... This one has a bit more focus on resolution and capbilities: https://www.universetoday.com/143298/thanks-to-trump-weve-go...

Unmanned, 98 feet long, and mach 6 sounds like a lot could go wrong. Lot of kinetic energy there. I know we already have (close to) this with missiles, but they tend to have A->B missions.

And the X-men have one that hovers, too. And even fly into the back of.

You may object that the X-men and their plane are not real, but then you get dangerously close to the truth.

Given satellite technology and ICBMs, can someone explain why my tax dollars are going to this science fair project for adults?

ICBMs are a large, blunt weapon. Their value is primarily in their deterrence. The concequences of actually using them are so unthinkable, that we don't really consider it unless it's a very-last-resort kind of situation. Most of the time you want a precision, guided munition that can destroy a house or a truck or something small without causing too much collateral damage. Until now, that has meant an airbase or a carrier nearby to launch aircraft to carry these munitions.

However, with the XR-72, we can do away with those and just launch our precision strikes from the US mainland. It's cheaper, just as effective and hopefully will give emerging superpowers (like China) pause when planning their defence scenarios.

How is China supposed to know if one of these is carrying cameras, conventional bombs, or a warhead?

They aren't. But the trajectory means they can see it isn't aimed at Beijing.

ICBM go up and down in a predictable arc. Sometimes they have the capability to shift their path actively but not by much. Hypersonic controlled flight vehicles have the ability to be unpredictable and therefore offer more protection from countermeasures.

FOBS does allow you to at least change that arc so you can effectively come at a target from any direction:

https://en.wikipedia.org/wiki/Fractional_Orbital_Bombardment...

Bc there's some treaty prohibiting space-based weapons smth smth... hence your satelite will not be able to carry missiles (or use them without admitting it carried them).

...and bc ICBMs are not weapons you'd want to EVER see used :)

You'd probably use this to hit a bad guy's house/hospital/school inside airspace protected by another superpower (hence drones and other stuff won't work) based on ground based humint whose information will likely be stale after a couple hours. It could mean way less victims than conventional warfare, so ugly as it is, it's better than destroyed cities and waves of refugees.

All in all cool to see superpowers doing dick measuring contests with these kinds of stuff, compared to other horrible stuff they could be competing at militarily...

> Given satellite technology and ICBMs

I see an SR-72 being a hedge against losing both of the above, or having them rendered ineffective.

Putting a nuclear munition on this thing makes sense to kind of get ICBM like capability in a ditch, and ensures you have something against the enemy who can reliably intercept ICBMs.

Same for the case spy sats get taken down. The chance of the enemy having something that can intercept high speed aerodynamic targets, as well as satellites at the same time is minimal.

I'm going to attempt to answer your question.

First, it's unlikely that this is a real project. War companies produce lots of random ideas for presentations hoping that one of them will catch on and get an initial program funded. A few years ago there were animations of a V22 mashed up with a C130 to get a tandem winged VTOL cargo plane. The warporn gets buyers in the mood, but what they actually buy are things like the F35 program and "palletized strike missions", which is a mid-air launch system for cruise missiles. Every cargo plane with an in-air openable ramp becomes a cruise-missile launching bomber.

Second, some prototype projects provide cover for other, more secret projects. If everyone knows that a lot of engineers are being hired for the SR-72 project, the fact that 25% of them are actually working on something else in the same facility is easy to disguise. Test flights of one hypersonic vehicle look pretty much the same as test flights of a different hypersonic vehicle.

Third, war companies provide a lot of skilled through professional level employment in the areas where they operate, and politicians find it acceptable to run employment programs that way.

Well we need to feed the beast because we love freedom and if you don;t you are free to go to gulag... or something along those lines.

Hypersonics is like fusion, everyone needs to be doing it. They’ve been trying for decades and so far it’s been a bust.

Queue news stories about Chinese or Russian hypersonics with zero real data and calls by the MIC to close the “hypersonic gap”

In the pantheon of weapon systems it is simply the most expensive way to do something.

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