Hacker News new | comments | show | ask | jobs | submit login
America’s Fastest Spy Plane May Be Back and Hypersonic (bloomberg.com)
138 points by adventured 6 months ago | hide | past | web | favorite | 126 comments

Reading this, I just realized that I bet we do more and more testing of cutting edge aircraft in computer simulations nowadays, waiting until later in the stage to actually build prototypes.

This might also explain why we've got fewer "UFO" sightings than we used to even 20-30 years ago, in spite of all of us carrying cameras in our pockets (apart from the fact that many of these were hoaxes to begin with).

For hypersonic it's been all about computer simulations. The costs are just too high. The tests for such aircraft are very expensive and typically result in catastrophic failure (complete loss of the system). Though they learn a lot about what works and doesn't in each test. A major driver for better CFD has been to better simulate hypersonic speeds and reduce the number of real test flights needed.


Someone in the FEA/CFD/Simulation industry upon seeing the SpaceX video on their capability indicated that no commercial product he was aware of could match what they were doing. Firewall won't let me confirm this link is correct:


SpaceX has best in class hypersonic combustion CFD capability that runs on a GPU. Written in-house.

To be fair, it is a VERY hard problem. 'Most' airplanes are designed in a laminar flow situation. Meaning that turbulence is just left out. This makes the calculations much easier, as you can set boundary conditions. In super-sonic conditions, the air is no-longer in-compressible, so the boundary conditions change and you have to add more variables to the equations. In hyper-sonic flow, the air itself is now a variable, as the molecules are split and recombine along the wing in ways we have not yet even empirically measured. This ads a complexity to the equations that is very large and the 'educated guess' of those chemistries on the wing becomes very important.

...as the molecules are split and recombine along the wing in ways we have not yet even empirically measured.

I'm sure one can speculate. In the video they do talk about all the possible intermediate species, so one might have to add air molecules (which can break apart and add to the reactants) to the mix. But yeah, lots of unknowns. Doing experiments and comparing to the simulations should help figure it out. The problem has traditionally been an inability to do the simulations, but that's possible now.

It's the political cost of failures that makes progress so slow.

Compare SpaceX and SLS / Ares.


there are still places which put models into chambers. (I know, I used to work behind this one, and we have a steel membrane punched through by the airblast to make the shockwave from the dumpster out back)

”I know, I used to work behind this one, and we have a steel membrane punched through by the airblast to make the shockwave from the dumpster out back” I can’t parse this sentence. Could you explain? Thx

I think the commenter is trying to say they have a steel membrane that had a hole punched through it by an air-blast. Said membrane came from the dumpster out in back.


the part called "primary diaphragm"


And also of engines - one of the reasons relatively small companies like SpaceX and Blue Origin can design their own high-performance rocket engines is that they can simulate combustion and fluid flow using CFD techniques. Back in the F1 days they had to light up the engine and come up with interesting ways to observe the internal processes and debug instabilities; now many of those debug cycles (and associated manufactured test articles) are unnecessary. You still have to build the thing to catch some bugs, but that's gotten much cheaper.

Also CNC and 3D printing have made iterating hardware more possible with less labor. One person teams now can get liquid rocket motors printed. Of course turbopumps are many levels from that.

I don't think there are fewer "UFO" sightings than there were 20-30 years ago. I think there are way more. You don't have to dig very far on YouTube to find giant communities of people who are "seeing" UFOs. Video evidence of UFOs is easy to collect -- all you need to do is not identify the objects in the sky. And there are all sorts of weird things in the sky -- reflected lights and spotlights, weather balloons (and regular balloons), drones, sundogs, regular planes, satellites and the ISS, even the occasional actual meteor.

It's also much easier to ignore these things, since most of them are just ordinary things that the person who took the video doesn't know how to identify. If you made a great UFO hoax now, chances are nobody would ever see it who was the least interested in looking at it skeptically, because it would be lost in the noise of people seeing trash bags blowing in the wind.

So I think that https://xkcd.com/1235/ is premature about UFOs, though I think it's pretty conclusive about lake monsters and bigfoot (although if you look around, people see a lot of strange looking mangy bears that people think are bigfoot).

One thing that is getting harder is taking really shitty video that is impossible to interpret. Phone cameras are getting better every year so the kind of grainy shaky stuttery video you normally get with these cases becomes harder and harder to justify.

> This might also explain why we've got fewer "UFO" sightings than we used to even 20-30 years ago, in spite of all of us carrying cameras in our pockets.

At night, though, we can still see a lot better than the cameras in our phones.

For instance, I saw something weird one night. It was big enough and bright enough that I had no trouble seeing it, but my iPhone 6 plus camera just got a vague blob. This was not a UFO, since among other things it was on the ground, but it illustrates the limits of the cameras.

(In case anyone is curious, I'll describe what I saw at the end of this comment).

The most interesting current UFO reports I've seen (interesting in the sense that they are probably something real--not aliens or supernatural stuff of course, just either an unknown natural phenomenon or some manmade thing that is not well known) are where people see what looks like a star, but moving in a straight line (sometimes pausing now and then), that then suddenly changes direction and zooms off over the horizon very suddenly. No way is a phone camera going to capture that.

The weird thing I saw: this was the night before the 2017 total solar eclipse in the US. I was parked in a big field that had been turned into a car camping area for the eclipse and the day/night before.

A few rows down and a couple dozen spots to the left I saw what looked like two copies of a movie or TV show side by side, kind of wavy and translucent. It looked like either they had hung up a sheet and were projecting video onto it, or they had a couple of flat panel displays and there was a sheet between them and me.

Then what looked like an arm poked up. If they had been in a tent I would have said it looked like someone in the tent was pushing up on the top, stretching the tent--but tents were not allowed. (There were some trucks and vans that had tent-like extensions on top, so they may have had something like that). The arm moved back and forth a while, and then was apparently pulled down.

Then what looked like a leg replaced it...but it was a huge leg. It looked to be about 2 meters long. The "leg" started moving rapidly back and forth along what would be the length of the vehicle. After it had done this a few times, it disappeared. (There may have also been an arm or two mixed in here).

Then a light rose up from the middle of the vehicle. I though it might be a flashlight. It then stopped rising, and started turning. It continued turning until it was pointing right at my car, and then it stopped turning for about 10 seconds. Finally, it resumed turning until it went all the way around, and then it descended, and things were dark, with no activity at that other vehicle.

I thought "what the hell was all that?".

Then the images came back, and the whole thing repeated!

The third time it happened I had my phone out and the camera recording. Unfortunately, all the recording shows is that there was some lights moving around in that direction.

I'm guessing a young child had a pool noodle under the tent and was moving it around as their last hurrah before bedtime, or maybe it was just hippies.

Ah yeah. That is strange. I know what that phenomenon is though.

It's called you were on mushrooms bro.

I haven't done mushrooms since once at college. There's a funny story about that time.

There was an annual organized trip to Disneyland at my school, and a large fraction of the student body went. I decided not to go that year, and picked that night to try mushrooms because the campus would be sparsely populated. I figured that the fewer people there were around, the fewer chances there were for something to go wrong.

I had done a lot of reading, and talked to a lot of people who had used them, so that I knew what to expect on a mushroom trip. I was seeing and feeling the effects I expected, and having a good time.

Then several people I did not recognize walked by, speaking Chinese! Then more Chinese speaking people walked by. That was weird. I started wandering around campus, and kept running into people I did not recognize who were speaking Chinese.

This was very unusual. My school (Caltech) was small enough that every student could normally recognize every other student by sight, so seeing so many strangers was odd enough...but that they were all speaking Chinese was just freaky.

Nothing I had read or heard said that mushrooms could make one have that kind of hallucination, so I was starting to get seriously worried that I was on more than just mushrooms.

It turned out that I was not hallucinating. I had not been the only one who decided to take advantage of most Caltech students going to Disneyland that night. The Chinese Students Association picked that night to throw a party and invite the Chinese students from UCLA and USC and nearly every other college in the Los Angeles area.

I don't think even modern day smartphones are fast enough to capture objects traveling at hypersonic speeds. Just a guess, I may be wrong here.

Distance makes speed irrelevant. The moon is traveling 1km every second but that's hard to directly notice.

If you every watched a jet moving at ~600mph then I think we can agree something going 10 times as fast would still be easy to notice.

Possible to capture if you noticed it anyway.

Jets cross out of view in a couple minutes and are big (and probably flying lower). So a little thing in ~20 seconds.

If it's tiny, dark, and distant then it's hard to see even if stationary. Thus the real issue would not be speed.

Yeah, I was agreeing with that part of you comment and quibbling over "easy to notice".

Even with the tiny size the speed is still a big factor because the opportunity to sight the object from a given location will be pretty short.

Take something like an SR-71 blackbird... It flew subsonic until it was often near the edge of space. If it was vaguely near takeoff or landing, it would be possible to see with the naked eye.

If you're a fan of the SR-71, this hilarious interview with pilot Brian Shul is definitely worth watching:


They are able to capture rocket launches so it should be OK. A hypersonic plane will be very high altitude so it won't move across the sky that fast. The ISS needs several minutes to cross the sky.

It's not going to be hypersonic 100m from the earth's surface, or it'll burn up. So it wont be because of speed i'tll just be too far away.

It is noted in the article that this airplane has no real mission profile. I mean hypersonic cruise speed is an impressive feat on its own, and may result in new methods and applications in space travel. But the military usage of a plane like this is questionable. Recon aircraft have long since been abandoned in favor of satellites, and a fleet of bombers might not be maintainable because of the huge costs involved.

Satellites can be re-oriented into different orbital inclinations but that requires fuel and in the absence of a Shuttle fleet they cannot be refuelled. So despite movie depictions they don't go swerving hither and thither to follow a camel up a mountain track.

Such limited manoeuvring also requires planning and 90 minutes between passes. Lots of opportunity for bad guys to push their missile back into a hangar.

An atmospheric aircraft can follow an arbitrary course to take in as many targets as required, can be rerouted on a moment's notice and can approach from unexpected vectors to catch the target out in the open.

> in the absence of a Shuttle fleet they cannot be refuelled.

Judging by the publicly-released payload specs for the DoD-operated Boeing X-37 spaceplane, it should be able to deliver about 2000+ L of hydrazine, compressed Xenon, or other suitable fuel in a single launch.

Edit: It looks like DARPA has been experimenting with "space gas station" experiments since at least 2007.


> Satellites can be re-oriented into different orbital inclinations but that requires fuel

A LOT of fuel. So much so that even if lifetime wasn't an issue, it makes more sense to launch additional satellites in the proper inclination, rather than moving one.

I know that, in one instance, a company wanted to use the moon's gravity to change a satellite's inclination, as it was cheaper to all the way to the moon and back (and then circularize again). That maneuver seems to be patented, though.

Patents be damned, I use that in KSP from time to time. Can I claim prior art? If you're on a level orbit and you fly off to the moon, adjusting with a tiny bit of inclination so that instead of nearing the moon on the same plane but from above, you're suddenly in a highly inclined orbit on your way back. You can also use this to slow down/speed up depending on which side you approach.

Patent number/reference please? I’d love to use this as a test case in an orbital dynamics library I’m building.

I am fairly sure that "US 6116545 A" [1] is the patent in question.

[1] https://www.google.com/patents/US6116545

Sure, but don't we have drones for that now?

The high altitude spy planes (U2, SR-71) were mostly to prevent being shot down; surviving to return the film to base.

Drones don't need to bring film back, and it's not such a big deal if a few of them are lost.

Just speculating here on two points:

- There is no real need for SR-72 to be manned on all flights;

- Hypersonic plane would be very good for small (2m wingspan) drone delivery behind the enemy lines fast (in half an hour). This was already a concept with M-21/D-21, but now the drone part can be much smaller and one plane could carry more than 4 of those.

Satellites are quite limited when you need to make fast decisions. Hypersonic plane will move about 7 times slower than an optical recce satellite, yet it can maneuver very fast if you need to relocate the imaging area and can get at least 10 times closer to the target. Instruments can be selected/improved even after the first flight of the plane -- not true for the satellites.

If it can be shot down, I think that it's probably safe to assume that it won't be able to see anything particularly interesting. I'd expect something like Groom Lake to be surrounded by an impenetrable wall of interceptors and SAM sites.

Though I suppose that you could try to make your drones so cheap and in such volume that shooting them down becomes logistically and economically infeasible, but that's another strategy entirely.

> I'd expect something like Groom Lake to be surrounded by an impenetrable wall of interceptors and SAM sites

The whole idea of the SR-71 was that it went so fast that SAMs could just barely not catch up to it before they ran out of fuel. Any other plane couldn't outrun them, but the Blackbird? Well, Mach 3.4 will give you some breathing room.

More to the point, it takes time to notice, track, lock and (in some cases) get approval to fire. That gives you seconds to minutes to not only fire but for the missile to reach the intercept point.

Missiles and radar tend to operate in a "bubble". Even with the Russian S200 system at 190 miles range, the time you spend in that "bubble" when you're at 70k ft is not often long enough to do anything. That also assumes the aircraft directly overflies the battery. You can play games like pointing the camera sideways and observing from an angle if you know there are going to be angry people with guns nearby.

Mach 3.4 was also fast enough that early radar systems couldn't track it. The plane would move far enough between radar pulses that it got filtered out as noise.

The standard evasion tactic for SR-71 upon launched against was to simply accelerate.

That would be the only option. It's not like you can turn much you'd pass out or snap the airframe.

I imagine thought a little snake left/right might compromise getting the images that was the point of the mission.

Apparently it could also turn pretty hard. Mind, it's turn radius was huge, but at mach 3.2 it still meant pulling a lot of g's.

The state of the art advances. There are SAMs today that can shoot down ICBMs. I would guess that one reason the SR-71 was retired, besides the official line that it was expensive and made obsolete by satellites, is that it was no longer invulnerable as it had been when it was new.

I always imagined spy satellites in a 'string of pearls' kind of configuration. Rather than having 1 in some specific orbit, have 4 or more in the same orbit. your 90 minute return time gets cut to ~20 minutes or less. Obviously, i have no information either way.

There's no need to imagine. The quantity and orbits of spy satellites are public knowledge since there's no way to hide anything in space. The exact capabilities of each satellite are classified but but we can guess how good their sensors are just based on physics. Currently it costs so much to build and launch a spy satellite that we can't afford to put a bunch of them strung out in a single orbit, but maybe that will become practical eventually as launch costs decline.

> The quantity and orbits of spy satellites are public knowledge since there's no way to hide anything in space.

The "Misty" satellites came up on HN last week related to the SpaceX launch and failure.



"A week after launch, reports were released from the Soviets that six bits of debris had been detected suggesting an explosion had occurred. The Pentagon announced that any debris would decay after six weeks. The amateur astronomers and observers that were tracking this object only catalogued five out of the six pieces. Six months later an unidentified satellite was discovered in orbit on a similar trajectory to that of the classified payload was released, leading the satellite spotters to suspect it was the missing piece, nick-named Misty. However a couple of noticeable manoeuvres later, Misty disappeared again. Perhaps the ‘explosion’ was a decoy to put Misty into place unbeknownst to the Russians."

Planet is doing this with many satellites today. They are much smaller than DoD projects so it's much cheaper.

Here's a diagram of their style orbit: https://www.planet.com/docs/spec-sheets/spacecraft-ops/monit...


that's a weirdly specific shuttle refueling point, dingaling. satellite servicing of any kind was very rarely attempted much less regular refueling. We can and do change orbits using onboard fuel without ever refueling - sure it's limited. Saying the shuttles supported refueling and hence maneuvering spy satellites are no longer a thing is very far from reality.

1. The Space Shuttle flew a large number of lengthy, classified missions.

2. The Space Shuttle suffered from many costly design compromises due to its excessively large hangar bay.

Given #1 and #2, there are four likely kinds of classified missions that the Space Shuttle undertook.

1. Stealing Russian military satellites.

2. Returning American military satellites to Earth.

3. Launching American military satellites into unpredictable orbits.

4. Refueling American military satellites, which allowed them to change to a new, unpredictable orbit.

It's entirely possible that the Space Shuttle only engaged in some of these tasks... But it's difficult to conclude that given the very odd design of the space shuttle, and the very lengthy missions that it undertook, that no satellite servicing/orbital shenanigans took place.

Yes, satellites can change orbits using on-board fuel reserves, but due to the tyranny of the rocket equation, those reserves are limited - and are unlikely to allow a very large inclination change (Inclination changes are incredibly fuel-expensive.)

The Space Shuttle certainly didn't steal any Soviet satellites. The Soviets had radar too. It's physically impossible to do anything like that in space without getting caught. Furthermore the Shuttle couldn't get higher than LEO so many satellites were simply out of its range.

Likewise there is no such thing as an unpredictable orbit. Orbits are predictable, by definition. Any country with a good set of radars, telescopes, and IR sensors can find the exact orbit of every single satellite.

The Space Shuttle was certainly used for launching American military satellites into regular predictable orbits. They might have done a refueling mission at some point as a proof-of-concept but even that seems unlikely considering that it's always cheaper to just build and launch a new satellite.

The shuttle did not fly a large number of missions to begin with... It was so unreliable (fatal accidents every fifty launches!) that it never had a chance. The SpaceX model of reusability looks a lot more likely to deliver.

If SpaceX succeeds at lowering launch costs then it would be easier to launch many small and disposable spy satellites than ever to bother refueling one.

Nonetheless, the point is that satellites are limited as to opportunities due to limited availability and limited time windows. This does argue that there ought to be a role for an SR-71. I'm not sure there's much of a role for an SR-72, but certainly for the SR-71 there ought to be.

Yeah, but a low, slow, cheap drone has all those advantages anyway. There's no need for a hypersonic space plane.

What's the point of having people in this?

To operate it.

Recon aircraft still exist. The USAF for example still operates U2 planes. Satellites lack the critical ability to stay in place and cannot necessarily move to a designated spot at short notice. While spy satellites are certainly more maneuverable than regular satellites, they still must obey orbital physics, a plane is not bound to those restrictions.

How maneuverable are you at 6000 mph? You’ll flyover the US in 30 minutes.

With a roll of film nearly a foot wide and lenses that can pick a gnat off a flea pointed at the target, the pilot can get instructions in the air immediately before penetrating "contested" airspace and get crystal pics of everything on the fly at any speed he wishes. Max potential velocity over the target is mainly to insure survivability; it doesn't affect photo performance.

our existing spy planes and drones are subsonic and work just fine loitering over poorly-defended targets.

stealthy or speedy aircraft could work over more hostile places and add to the satellite capabilities. Maybe there are things you can sense from 10 miles up that you can't at 100mi. And maybe there's some brand new gear that you don't have in space yet. And maybe you want to time your picture with some unpredictable events on short notice. there are a ton of reasons to have this variety of capabilities.

You don’t need to fly 6000mph, however. Planes have the ability to adjust their speed, satellites don’t.

Sure, and at what speed to you become a target to local missiles? I’d like to see a hypersonic plane for the engineering it will solve, but I think as a spy plane, it has limited utility.

It’s not like satellite killer missiles would be a new thing, they’ve been developed since the 1950s

Space isn’t owned by anyone. You are legally allowed to have satellites over another country. Flying over another country is completely different.

Which is why the USAF never had a plane shot down over the USSR as Gary Powers will certainly be glad to confirm. It’s also the reason no US planes ever fly over Syria, Irak, Afghanistan, Pakistan or any of the numerous conflict zones that the US is involved in. Also note: My point is not that satellites are useless, they are much more useful for continuous spying and surveillance, but there are numerous mission profiles that a plane can fulfill much better.

You’re all over the place. We are now allowed to overfly Russia.


When you control the sky’s you don’t need to fly at 6000 mph.

We have bases in Pakistan and Afghanistan, for example.

Which mission profiles are you describing that are actually needed to fly at hypersonic speed? A lot of these countries are quite small for that speed. A 100 miles a minute.

I’m pointing out that the legality of overflying a country has always been and still is a lesser concern.

Mission profiles better suited to a plane than a satellite: anything that requires loitering, returning to a target, anything that requires a curved path that a satellite cannot fly or anything that requires close up - optics on satellites are good, but fundamental physics limits the achievable resolution. Hypersonic speed might not be required to fulfill the actual mission, but it allows shorter response times on all spots. It also would allow evading most intercept attempts.

Typically above 60,000ft (FL600) is considered to be outside of a nation's airspace[1] (by ICAO at least) - which is one of the reasons why the U2 was designed to cruise at 60,000-70,000ft (FL600-FL700). The SR-71 could cruise up to 85,000ft (FL850).

So, technically and at least according to ICAO, these birds flew/fly above a nation's sovereign airspace. That doesn't stop a nation-state from attempting to down one of these birds, of course.

[1] https://en.wikipedia.org/wiki/Airspace

60,000 feet is the limit of controlled airspace, i.e. if you fly above it air traffic control will not guide you to make sure you don't collide with other aircraft. It's not related to sovereign airspace, the area where a country has the right to decide who may fly.

I think the general rule is that sovereign airspace covers air-breathing planes but not spacecraft. From your link:

> There is no international agreement on the vertical extent of sovereign airspace, with suggestions ranging from about 30 km (19 mi)—the extent of the highest aircraft and balloons—to about 160 km (99 mi)—the lowest extent of short-term stable orbits. The Fédération Aéronautique Internationale has established the Kármán line—at an altitude of 100 km (62 mi)—as the boundary between the Earth's atmosphere and outer space, while the United States considers anyone who has flown above 80 kilometres (50 mi) to be an astronaut.

You deploy autonomous drones that will loiter for an extended period.

That's exactly the point. If an unexpected threat pops up you can get there now.

> But the military usage of a plane like this is questionable

I could see utility in being able to rapidly deploy a team of special ops, or specialized unanticipated equipment, to a faraway location. That it can do things a missile can without being a missile is also useful. (Suppose you need a bunch of drones over a random location. You could launch a missile and risk (a) breaking your birds in launch and (b) someone thinking you're flying nukes. Or, you could use this plane.)

I could see utility in being able to rapidly deploy a team of special ops, or specialized unanticipated equipment, to a faraway location.

This won't be landing on any improvised airstrips, and a hypersonic configuration won't be able to go slow enough to drop paratroopers.

Couldn't you put the paratroopers in a drop vehicle, purpose built for that? We bring astronauts back at mach 23-25. That's not to say it wouldn't be quite an engineering effort. I'm sure they can find a billion dollars to build it if someone decides it's worth doing.

The more interesting impact would be on the design of the plane doing the drop. While I think you could keep the paratroopers alive, I'm skeptical there's any way you can go that fast and drop a large container. I would expect the process to destroy the plane by making it too unstable.

Couldn't you put the paratroopers in a drop vehicle, purpose built for that?

The Osprey is probably the fastest troop carrier, so you would need to identify some use cases it can’t do then figure out if the cost is worth it. Traditionally SF get there by jumping in and then hiking cross-country, is there a use case for getting them on the ground in a couple of hours?

This was my first thought too, because I've heard they've been working on deployment systems to get groundpounders to an AO very quickly, for example one of the rumored applications of the x37b being for HALO insertion.

Galus, what do you base your claim on that a hypersonic config can't go "slow enough"?

Considering the DoD's track record on ship and aircraft acquisitions, utility is pretty low on their priority list.

The military has to have contingencies in place for if all satellite communication were disabled, through some method or another. Should symmetric warfare between modern nations ever break out, satellite comms would be one of the most valuable and ostensibly poorly defended targets. You can't really assume much of anything about the status quo in planning for war.

1. How big a fleet does one need for a useful 1st strike capability? Perhaps not so many.

2. Higher resolution imaging could still be quite useful. For example, if we could possibly find all of the Chinese DF-21B anti-ship ballistic missile launchers, this erodes the deterrent effect of that weapon, which then increases the value of the US aircraft carrier groups.

The advantage that recon aircraft have over satellites is that they're not in predictable orbits. Assuming any new aircraft has better stealth than the SR-71 (say, on the order of what the first-gen stealth F-117 had), it can overfly the area of interest before anything can be moved under cover.

here's a hint at one possible mission profile: https://taskandpurpose.com/kinetic-bombardment-kep-weaponry/

Why would a propulsion system like this not be put on missiles first? Seems like there are many more tactical applications.

Turn it around: Why would a propulsion system like this be put on a missile?

Missiles are generally powered by rocket motors - they don't need air intake.

Missiles are also generally one-time-use - you send it somewhere and don't expect to reuse it (also it usually explodes)

I suppose it might be possible to increase payload per fuel efficiency, but the only reason the military would probably care about that is cost, and the rocket engineering is already paid for and proven.

The first missiles (V1) were basically ramjet engines, so it’s not exactly unheard off. The advantage of such an engine is that it doesn’t need to bring its oxidizer along like a rocket engine would need to, so depending on how the engines weight compares to a rocket engine, it would allow for more payload at the same total weight which might be interesting in various places.

The V1 use a pulsejet engine (Argus As 014), not a ramjet.

The difference between a pulse jet and a ramjet is quite small if you compare it with a rocket or a turbofan: Basically they're both air-breathing without a compressor or fan to compress the intake air, so I'd stand by "basically a ramjet".

The second and essentially all subsequent missiles were rockets though.

Perhaps you are thinking specifically of ICBMs? There are other types of missiles, not all of which are rocket powered.

https://en.wikipedia.org/wiki/AGM-86_ALCM - "All variants of the AGM-86 missile are powered by a Williams F107 turbofan jet engine"

https://en.wikipedia.org/wiki/Tomahawk_(missile) - "After achieving flight, the missile's wings are unfolded for lift, the airscoop is exposed and the turbofan engine is employed for cruise flight."

https://en.wikipedia.org/wiki/Harpoon_(missile) - "Power plant: Teledyne CAE J402 turbojet, 660 lb (300 kg)-force (2.9 kN) thrust, and a solid-propellant booster for surface and submarine launches"

https://en.wikipedia.org/wiki/Kh-55 - "It is powered by a single 400 kgf Ukrainian-made, Motor Sich JSC R95-300 turbofan engine, with pop-out wings for cruising efficiency."

The hypersonic missiles use a rocket to get up to speed, like:

https://en.wikipedia.org/wiki/Zircon_(missile) - "A booster stage with solid-fuel engines accelerates it to supersonic speeds, after which a scramjet motor in the second stage accelerates it to hypersonic speeds."

Yes, since ramjets with performance such as this one were outside our engineering capabilities. As the article states, even this one was not possible a few years ago.

It’s also not entirely true, tomahawk cruise missiles for example use turbofan engines with a solid state booster.

Some missiles already travel at these sorts of speeds.

Are you a disinfo plant? Recon aircraft still exist, perhaps more than ever when you consider the use of drones. And of course bombers are still a critical part of US global defense strategy

Video from SciTech conference https://livestream.com/accounts/6056055/events/8001237/video... starting at around 41 minutes

the bombshell part is from 00:58:58 - 01:00:28 where his phrasing is as if the hypersonic plane has actually been built within the last 5 years, with a 3-d scramjet engine (and 3-d printed as well).

There was something about the SR-71 Blackbird that really captured the feeling of the time. Whenever I drive the 215 past March AFB and see the one they have on display, it reminds me of the age of movies like Firefox and War Games.

This has been known for a while. Seismologists discovered it and tracked one at 5000 MPH. The ability to be anywhere in the world in a very short time is a compelling tool for the military.

Can you elaborate on that? I'd be very interested to see how seismologists tracked a plane. Can you pick up high-altitude shockwaves from seismographs?

This seems a bit "reading the tea leaves" to me. The statements in the article are easily read as "the technology that would allow this is new".

'a Lockheed vice president a “digital transformation” arising from recent computing capabilities and design tools had made hypersonic development possible.'

The "digital transformation" part alone gives this up as vaporware...

I won an essay contest in college that NASA set up regarding the future of supersonic and hypersonic aviation.

Even back then, supersonic, let alone hypersonic, aviation was such a pipe dream for civilian aviation. Not saying it can’t be done, but I can’t imagine the breakthroughs that need to be made would be made outside of any context short of a World War.

Let me list the problems:

1. Materials Science. Very hard to design materials that survive those kind of stresses, and that you know will last 30+ years. Airplanes routinely have 60 year life cycles, so 30 years of material survival is the minimum. The stresses on these things are huge. The Concorde would actually expand 10 inches from head-to-tail during flight because of the heat.

2. Overpromising dating back 40 years. My favorite example is Ronald Reagan promising an “Orient Express” that would be 90 minutes New York to Tokyo. That was in his 1986 “State of the Union”.

3. Acceleration. Flying Mach 6 is one thing. Having a plane that can accelerate up to that speed fast enough that the flight doesn’t already end, AND THEN slow down an equal amount, is another thing.

4. Sound. This sounds like a nuisance thing, until you hear one of these aircrafts in action. THEY ARE SO DAMN LOUD. It’s a health and safety issue almost. I would compare it to being around artillery fire, maybe worse. It stays with you for days.

The Japanese and Australians from time to time do some good work on this kind of aviation. Boeing had a civilian supersonic project in the 70’s, but it’s all been given up except for the occasional private jet or military experiment.

supersonic, let alone hypersonic, aviation was such a pipe dream for civilian aviation. Not saying it can’t be done

One word: Concorde.

I’d like to see the modified UH60 used in the bin Laden raid. The only hint of it’s existence is the remains of the tail section.

Interesting, I hadn't heard about that before, but here's a link to an article about it: https://www.defenceaviation.com/2011/05/stealth-uh-60-black-...

Having a degree in aerospace engineering and being a lifelong air and space fan this discussion is mostly disappointing. hacker news comments are of distinctly poorer quality outside the subjects of software and startups - sensation, urban legend, and ignorant story-telling is rising to the top instead of explanation, context, and insight. 8 of the top 10 comments are inane (UFOs! Movies! tinfoil-hats! Sophomore-year economics!).

Makes one wonder how much the mainstream hacker news threads are suffering from similar problems that I just can't perceive.

I can't see how even America's seventh fastest spy plane could be anything less than hypersonic, let alone the fastest one. :)

is that the follow up to the Aurora project ? https://www.defenceaviation.com/2007/06/sr-91-aurora-aircraf...

This is obviously cool on many levels but fundamentally this is very sad. This, while places in the US don’t have clean running water. The best national defense is creating a next generation that’s healthy, worldly and educated. Instead, this.

I’m not sure what your point is. We already spend more on education and healthcare per capita than almost every other developed country. At what point is it appropriate to spend the incremental dollar on defense instead?

I was with you until you called it the "incremental dollar". We spend 3x more on defense than the nearest competitor[0]—0.6 trillion dollars per year. Given that we only collect $3 trillion per year[1], after debt service we're not really left with that much.

[0] https://en.wikipedia.org/wiki/List_of_countries_by_military_...

[1] https://www.nationalpriorities.org/budget-basics/federal-bud...

I'm under the impression that if the USA doesn't maintain a significant level of military superiority, it will quickly find itself under duress from myriad sources.

This is a path which once you start down, you're somewhat committed to in perpetuity.

> I'm under the impression that if the USA doesn't maintain a significant level of military superiority, it will quickly find itself under duress from myriad sources.

Is England under duress? Is France under duress? Are the Dutch under duress? Is Spain under duress?

Most importantly, at what point do we ask ourselves what it is that we are even defending? 50% of the population making less than 5 richest people?

> Is England under duress? Is France under duress? Are the Dutch under duress? Is Spain under duress?

Those countries were under duress for years during the Cold War, and were protected by the U.S.'s massive military spending during that time. And given that Russia recently annexed part of a sovereign country, those times may be back.

Right, but Russia spends less than one tenth of what we spend on defense. Certainly the Western World can scrape together enough to defend itself from Russia. They took Crimea and Eastern Ukraine because they knew no one would do anything. I think they know where the lines are drawn, and I don’t know why those lines cost the United States $550-600bn per year to maintain.

First, unofficial estimates of Russia’s defense budget are about $70 billion: https://www.rt.com/business/russia-increases-military-spendi.... Second, Russia doesn’t pay soldiers US salaries. Russia’s purchasing power parity (PPP) GDP is 2.6x higher than its exchange rate GDP. Applying that same factor to Russia’s defense budget results in $182 billion. Third, we quite reasonably don’t want to maintain mere parity with our enemies. We want a decisive if not overwhelming advantage. That costs exponentially more money. It’s like Intel’s spending on fab R&D. Intel spends 6x as much as TSMC and 4x as much as Samsung. That buys Intel a well under 50% advantage in fabrication process over those companies. Or airliners. In constant dollars, the 777 cost twice as much as the 747. The 787 cost another factor of two more. For 4x the cost, improvement in fuel use per passenger mile is under 40%. It would be amazing if the less than 3x (real) difference in spending gave us even a twice as capable military.

So that is a compelling argument! Thank you.

It's easy to avoid duress when you share an ironclad alliance with the dominant military superpower in the world.

A useful perspective to look at the military budget through is: consider that outspending by multiples every other military power averts wars (because a WW2-scale war with the US would be suicidal). What's the price you would put on avoiding a war at that scale?

in my view the first stage of SpaceX Falcon is the thing which is most close to the hypersonic transport today. One can imagine that such reusable stage would accelerate the high-altitude/suborbital plane thus solving the task of having engines for different regimes. Cost-wise - the few millions such a reusable stage launch would cost isn't that far from ~$35K/hour costs of SR71 on missions of 10+ hours.

“However, Aboulafia noted, such a capability could also be considered a destabilizing development if a U.S. adversary decided to react preemptively to such an aircraft’s existence.”

In other words China and Russia may contemplate fighting WW3 now rather than waiting to be leap frogged. Fun.

China is already working on hypersonic weapons. They aren’t waiting for anyone.


China is always “working on” whatever the US is. Issue comes down to timing.

Similar to Russia. The increasing gap there of course is that Russia can't keep up with the US and China on investment, they're going to increasingly fall behind except in a few isolated segments of defense tech. Russia is becoming a second tier military power, if they're not already (that is, closer to Germany, India, France etc. than the US and China).

The US and China are now spending $1+ trillion per year on their militaries. The combined sum will likely eclipse the entire value of Russia's annual economic output in the next 15-20 years.

Is it just a budget game, though? How efficient is each country with their budget?

US spending one trillion dollars, and China spending one trillion dollars, it doesn't guarantee that they will be technologically matched.

It does not have to be symmetric. You only have to spend as much as you need to nullify an adversary's capability. Ex, one does not need to manufacture an aircraft carrier to counter one, you just need to take it out of action.

China is always “working on” whatever the US is.

Well, by definition, since half the components probably originate there.

“We couldn’t have made the engine itself—it would have melted down into slag if we had tried to produce it five years ago,” O’Banion said. “But now we can _digitally print that engine_ with an incredibly sophisticated cooling system integral into the material of the engine itself and have that engine survive for multiple firings for routine operation.”

They made a computer model that wouldn't immediately destroy itself. Let's calm down a bit.

I'm not saying they've actually built it. But "digitally print that engine" sounds to me like they're talking about additively manufacturing the engine.

"Digitally print" is used as a synonym for "3D print" or "additively manufacture."

Guidelines | FAQ | Support | API | Security | Lists | Bookmarklet | Legal | Apply to YC | Contact