When you're trying to hit something moving 20kt, with something moving 30-35kt, from a few thousand yards, it doesn't take much error in estimating speed, heading, or distance, to make them miss. It's honestly more remarkable that they hit at all in those conditions, even with a "spread" (shooting several along slightly different headings hoping one or two will hit).
Anyone with a copy of Silent Hunter 3 https://store.steampowered.com/app/15210/Silent_Hunter_III/ can experience this for themselves. Trying to estimate another ship's heading from a vantage point near sea level is maddening, even with the aid of a little recognition book which shows ships of that class at various relative headings, and as TFA says it's especially hard to tell the difference between perpendicular and near-perpendicular relative headings.
Mind you, this also explains why dazzle was a promising idea in the first place. Calculating Angle On Bow was already the hard part of ship-against-ship targeting, why not try to make it even harder?
SH3 vets plotted relative positions to get heading much more reliably, which was something that was also insanely difficult for sub captains.
With some trig you can get relative headings by taking bearing measurements, waiting 30s, and then taking more, but speed must be known.
To get full heading and speed you can do the same thing multiple times but now we're in a least squares problem and it has plenty of singularities.
The most reliable method for me was to pass in front of the ship submerged the fire tail tubes or turn around if you have enough time.
Insanely difficult for fast moving targets.
I played so much SH games from the first days on, that I went and did my PhD on tracking using bearing measurements (albeit mostly applied and only a tiny theoretical contribution).
Well, at least in WW2 they had mechanical computers that could use the input width of the vessel and the class to estimate the range, heading, and firing angle to set the torpedoes up. There's a good series of youtube videos by a sim player that teaches how to use the TDC: https://www.youtube.com/watch?v=ANk6hZCcVRw - it's very in depth, and demonstrates how much effort it takes to get a firing solution, as you say.
Adding to the difficulty is the possibility of observers seeing the incoming torpedoes and a fast-moving,
maneuverable ship dodging them.
Fast and maneuverable as in .. the USS New Jersey, able to sidestep a spread of five torpedoes from a Japanese destroyer.
I'm pretty sure that a lot of people are very happy with water resistance in exchange for having to do a bit more work to replace a battery (that they don't actually replace).
The number of people using their phones in the hot tub, or in the sauna, astounds me on a regular basis. I can't imagine doing that. But, with modern devices being genuinely "drop them in the pool" grade waterproof, neither does it seem likely to be a problem.
I'll agree on thinness, though. The number of phones in massive, chunky cases says "A lot of people don't care about thin."
> The number of people using their phones in the hot tub, or in the sauna, astounds me on a regular basis. I can't imagine doing that.
and the number of people who desperately look for a way to replace their batteries or upgrade to a new model just because their phone battery degraded is quite saddening.
I've suggested to a range of people that if their only complaint is runtime, and the phone is a few years old, getting someone to replace the battery is far cheaper than a new phone. It's a novel concept, and I'm quite unsure if people just don't know if that's a thing, or if that's the socially accepted excuse to spend a lot of money on a new phone.
A "user-serviceable battery," by requirements, is going to be a hard shell plastic sort of thing - which means a decent fraction of the "total battery space" is a protective layer, not active cell components - so some significantly reduced capacity compared to having a "non-replaceable" battery ("slightly more difficult to replace"). You also end up having to devote space to whatever mechanisms keep the rear shell in place, and may have a harder time waterproofing it as a result (which seems to be standard anymore - the number of people I see at the gym using their phones in the hot tub or sauna is boggling).
Batteries, under light use of phones not kept in pockets, last a very long time - 3-5 years isn't unreasonable, and many will last longer. Batteries, under heavy use of a phone kept in a pocket and run hard, will still typically last 1.5-2 years. So in exchange for "slightly more inconvenience less than annually," you get a good bit more capacity and runtime.
Apple, in general, hasn't made their batteries nonsensically hard to replace. They've used the "pull tab sticky" sort of thing for some while, which is far nicer than "glue the whole thing down," and their newer devices are using some sort of electrically released magic (apply 9V to the adhesive, battery pops out).
That's a whole lot of words to just carry water for a bunch of anti-user stuff Apple continues to inflict on their Stockholm Syndrome afflicted customers. The whole water proofing thing is dumb--why is it that every digital watch I've ever owned is simultaneously unbelievably easier to service and also manages to survive being under water way better than any phone I've seen, Apple or otherwise? It's like gasket technology doesn't exist. You could have your shiny metal back and just have it secured with a handful of machine screws. And as far as their batteries not being a pain, they're way harder than a Motorola, for example, and again frankly needlessly so.
It's so weird that we just come to expect to be screwed on these phones, when if it was anything else, especially the sort of devices that are more commercially focused than consumer, you'd demand better.
It was more to prevent unexpected shutdowns. Which, I'll add, were a problem with Android devices at the time, and the Nexus 5, in particular, had three battery OEMs, one of which would only last a year before being unable to run the device in high demand situations (say, "taking a picture with the flash").
As lithium batteries age, their internal resistance goes up - you can model a battery as a voltage source and a series resistor accurately enough. Over time, that resistance goes up, which means, for a given current, you end up with less voltage "at the output." Most power supplies will compensate by pulling more current to provide the needed power, which will drop the voltage more until you slam into the low voltage protection circuitry that cuts power.
The Nexus 5s are the ones I'm most familiar with, and they absolutely had this problem with one of the battery OEMs (the only way to tell which OEM you had was to pull the battery out, they were labeled on the back). The typical symptom was, "The phone shuts down when you try to take a picture," because camera modules are power hungry, the CPU was spinning hard to keep up with rendering the view from the camera (and possibly doing some pre/post frame capture to find the best frame, I don't recall when that showed up), and the flash pulls a LOT of current, very briefly. So everything would simply shut down when you hit the button to take the picture.
Apple decided to attempt to limit this problem, and they locked out the highest tiers of CPU performance (which are the most power hungry), if the device was having brownout issues. It's a reasonable enough strategy. Where they failed (IMO) was in not alerting the users that it was happening, or that it was a battery health issue. The later iterations of it, where it tracks battery health, and will tell you if your battery is going bad and needs replacement, are what they should have rolled out, and didn't. My guess is that they didn't think it was going to be a major issue for many devices, so it was just a CYA sort of thing that would prevent shutdowns. Unfortunately, that also happened right around the same time that US carriers started dropping the "New phone every 2 years on contract!" thing, and so the iPhones of that era started being used rather substantially longer than the previously-expected 2 years, and, Apple, so drama for clicks.
Had they just gone about telling users, "Hey, it looks like your battery is getting weak, would you like to schedule a replacement? Otherwise, we've limited performance slightly to prevent shutdowns." - I think it would have been fine. And they did settle on that eventually. It just took a few iterations.
I experienced those shutdowns several years before that update was released when I was using an old worn out iPhone 4. Several times it died on me in the middle of an important call at 30-40% battery. I would’ve absolutely preferred it slowing itself down if it would’ve prevented that.
It wouldn’t have hurt to include a setting, but I think turning it on by default for devices under a certain threshold of battery health at least was the right call, both because of non-technical users who don’t understand it and wouldn’t turn it on or those who would leave it off and then attribute the crashes to unrelated things (“they put crashes in my phone to force me to buy a new one!”)
There was no need for anyone to guess what was happening when their phone crashed, and there was no need for any default behavior at all. Every time I let my battery SoC go below a certain percentage -- 5% or 10% -- a message pops up asking if I'd like to switch to low-power mode to extend the remaining charge. I appreciate that. Nobody ever objected to that. No lawsuits were filed, no outrage was farmed on Facebook, no hit pieces were published by Bloomberg. So why in the world didn't Apple do something similar following a crash?
The dialog box practically writes itself. "Sorry! Your iPhone has just recovered from an oopsie-poopsie caused by a tired battery. Please choose an option: <Continue operating normally for as long as possible> <Reduce performance to extend battery life> <Schedule an appointment at your nearest Genius Bar to install a new battery (and check out the new iPhones!)>"
It's utterly inexplicable the way they handled this. Someone should have been fired. But then we say that a lot about Apple around here, and it never seems to happen.
I'm guessing you've not dealt with power electronics and batteries terribly much.
Depending on what limit has been hit, it's quite likely there is no way to log the cause of the error. Low voltage protection circuitry on most batteries doesn't have a status line. It's never supposed to trigger except in exceptional cases, and it just cuts power. All you know is that the power disappeared suddenly, and you've rebooted. Telling the difference between that and assorted other hardware faults, especially if you never designed the hardware to look for it, is really difficult.
You can certainly design a system that will latch the cause of the shutdown in the battery management IC - but you can't really add this in after the fact.
Sometimes things are much simpler than they seem at first. You set a nonvolatile flag at startup time: badShutdown=true. Prior to shutting down normally, you clear the flag. Then, if the flag is ever found to be set at startup time, you can assume that a crash occurred.
Whether the crash was really due to the battery can be inferred from the battery's age. If the battery is relatively new or is otherwise determined to be OK, don't issue this particular warning. If it's within, say, 90% of the expected service life, then the warning makes sense.
In any event, logic similar to the above was employed at some point to determine when to degrade the phone's performance. That is the point where the warning should have been issued. There are no valid excuses for not doing so.
> My genuine hope is that secretly we actually are really good with drones and just strategically have decided not to broadcast it...
What would you call the Reapers and such? The US has a massive fleet of large, armed drones, remotely operated, and quite a few are capable of being armed.
True. This is a very different class of drone. What is the defense against an adversary who releases a thousand quadcopter style drones against a US aircraft carrier?
The carriers aren't sailing around alone - they're escorted by a whole fleet (plus air patrol) that will intercept the drone launching vehicle at multiple dozen nautical miles range. Smaller quadcopter drones won't even get close to catching the carrier (which can travel over 40 kts while evading) before their batteries die. And even if a few hundred got through, how much damage can they really do? I'd imagine the flight decks can be patched quickly, although some radar equipment & any jets parked at the time of the attack would probably be lost.
It's definitely a concern as part of a larger attack, but I don't think a quadcopter drone swarm alone is likely to sink a carrier or leave it combat ineffective in the long term.
Agreed. But there's going to be "happy medium" drones that can be delivered by a long-range mothership. Price is no object when you can take out a carrier.
That's just silly. For attacks against surface targets, the bombers or strike aircraft (possibly unmanned) are going to continue carrying large, fast cruise missiles just like they have been since the 1960's. There is zero reason to use quadcopter type drones for this mission.
The type of quadcopter style drones that can be produced in the thousands have very short range and limited sensors. How are they going to get to the aircraft carrier? The lessons learned in a land conflict in Eastern Europe have little relevance to the Pacific Theater, where the US Navy intends to focus now.
The book from a year or two ago, "Means of Control," by Tau, goes into some pretty good detail on the data collection and sales from just the adtech firms - where the entire ecosystem seems to be, "You can't use our data for anything but advertising... wink wink", and everyone knows exactly who is bidding on ads, and never winning any, just to slurp up location data and sell it. Or the "companies that don't sell the government." Also, they don't vet any clients beyond "The credit card is good."
> And because giants like Meta, Google, and Apple must collect as much of your personal data as possible, there’s little they can do to protect your privacy.
I quite disagree with the "must" there. They choose to collect as much data as possible, because that's their business model.
And the good news is, it's fairly easy to opt out of quite a lot of that.
Turn location services off, turn your phone off when moving about, and pay cash without "personal tracking cards" associated with you. Just about everywhere has [local area code] 867-5309 registered, if you care.
I was watching this old British show called connections where they try to connect random things in the world together and they talk about your online persona and how the world will change because of the internet and World Wide Web. What I found interesting is that they present it all as if there will be an online version of you that you should treat, essentially, as a separate entity. It is not you, it is your representative to the digital space. That you should think of it as some agent that does things for you in that space even though in reality it’s simply a collection of data about you. But I liked that idea because it helps create a delineation between you the person and your online presence. I think what people don’t realize these days is that it is rather difficult to be anonymous online in the same way it is rather difficult to be anonymous in a room full of people you know. This is because your online profile is essentially known to any online actor who wants to know as you and the article point out. But tbh I think most people, including myself, spend too much time engaging in doing things connected to online. You don’t need slack and zoom to talk to colleagues it is possible to have in person interactions. You don’t need strava to go for a run. You don’t need your phone to go to the coffee shop and read a book.
I’m a big fan of the show. People who only use Facebook, I don’t expect them to dress their speech based on anonymity. People who actually fear a surveillance state, same deal. So how shall we depict the minority (on HN and IRC, etc) who expect anonymity as a feature?
The basic rule of thumb is, if a company knows something about you, then the government does too.
Which means they know everything you have posted, everywhere you've gone, everywhere you've worked, what you think politically, and almost certainly have AI profilers trying to "precog" you.
To say nothing of camera surveillance, gait analysis, facial recognition, license plate tracking, cell phone signal interceptors.
All it takes is for one authoritarian to walk in and turn the key and POOF we have perfect.
Are we in danger of that? Oh right, no politics on HN. Don't worry, be happy folks.
A one-off or series of authoritarians should be the least of your concern. They tend to be controversial and have great difficulty amassing the political will to get their things truly done and set in stone. A constantly popular government should be what keeps you awake at night. Because people who are otherwise capable of "hold a job, support myself" levels of intelligent thought will tie themselves into knots to support otherwise unjustified screwing at the hands of a government they support.
For a couple of years now I've been using [my area code] - 555 - [a unique 4-digit pin] for dealing with otherwise "walk-in" business that look at you like you have three heads if you decline to say a phone number out loud. In the US at least, the 555 block is defacto "fictional" and typically isn't assigned out, so it lets me create a valid looking number that won't accidentally ring some random real person if they try to call it.
Minor quibble, 555 isn't fictional, it's typically reserved for teleco internal use, or at least that was the case 25 years ago, who knows what the deal is now. Used to be you could wardial 555-xxxx and end up with all kinds of weird AT&T field installations, back office numbers, switch remote command and control modem numbers, etc.
Its like expecting farm animals to keep track of how the farm works, as the farm gets more and more sophisticated in animal domestication and exploitation. The individual action argument was weak 10 years ago and its worthless today.
The is a Systemic problem. Doesn't matter what the individuals do.
The trouble is people thinking it can be fixed with the system. I've been to a few dictatorships, none of them had the slightest clue what I was doing because the government was too poor and distracted with stuff like militias at their door to take much interest in what I was doing.
Safety comes from dysfunctional governance. Surveillance is a property of functional governance. Embrace disfunction.
Plenty of ineffective dictatorships will happily line you up against the wall with bogus surveillance. And shitty surveillance states will happily fake surveillance or data to look more effective.
The danger with these types of
State organs is they are constantly trying to justify their existence and cover up their mistakes, and if you can be thrown in the gears, some places are happy to do that.
>Plenty of ineffective dictatorships will happily line you up against the wall with bogus surveillance. And shitty surveillance states will happily fake surveillance or data to look more effective.
Sure, but that's the exception. Governments have a pyramid of needs too. Governments don't throw a bunch of resources on things with poor returns, like shooting people who haven't done much wrong, when there's easier fruit to pick. Sure, you can go full jackboot on specific issues here and there but that's not sustainable on a "will I retire in peace of will I hang from the overpass" timeline. And even if you're the dictator's henchman and want to go down some rabbit hole of killing people you don't like the the fact that the dictator may have you shot for waste or as a sacrifice when that provokes unrest or dissatisfaction among the people generally keeps the government in line. And the government really doesn't want to be killing people because it needs people to do things and pay taxes.
Look at all the historically violent dictatorships that lasted a long time and for many leaders. They all provide for their people generally. They might not be competitive absolutely but they keep things generally moving in a positive direction decade over decade and keep the country doing at least as well as its peers. The ones that don't tend to fall apart after a couple bad leaders.
I really shouldn't need to be explaining this. This is how every European monarchy worked just with god and birthright as justification instead of backroom dealing and politics and false elections.
Im sure when I fought for the YPG Assad might have liked that, unfortunately all the bogus surveillance in the world is no use when your army cannot enforce their borders or sovereignty. In any case I saw guys with AKs posting to Facebook, no bogus stuff needed, they were already publicly providing all the evidence needed for the death penalty without any worry of being prosecuted.
I don’t think we’re disagreeing. My point is that while those folks shooting AKs in the air are doing their thing, some other random putz that never did anything like that is probably getting nailed to the wall by the same system.
And unlike an effective/accurate surveillance system, you can’t be safe by just not being the AK weilding guys. In fact, sometimes you’re safer because you’re more dangerous, and they’d rather find someone easier to pick on.
Third world places aren’t what they are because of a lack of rules or systems (usually), but rather because the rules and systems aren’t fit for purpose and produce the wrong outcomes.
Ah yes absolutely. Under no system is anyone safe if they're unable to bear arms to protect themselves/family, they will be systematically vulnerable or vulnerable to the next bandit. This just becomes more visible under disfunction.
> And the good news is, it's fairly easy to opt out of quite a lot of that.
The problem is that we really need something like herd immunity. If you opt out, but the rest of the people in your life do not, then it's possible to discover most of your data most of the time. You might have location services off, but your friends and family don't, so much of the time there's a good guess where you are at. Or you might not share your phone #, but it can be collected by those that you text or call and shared that way. Creating "shadow accounts" is very advanced these days.
Not to mention, "opt out" has to be actually true and not just a facade.
Just don't bring your phone with you. With low power states and opaque software and hardware, you really can't risk it. You can never be sure it's truly off, unless it's in a Faraday bag. But is it worth it?
The magnetic field passes through a Faraday cage, so even then there are no guarantees if the phone uses unconventional modes of communication. Ultrasonic audio is another one.
It is impossible to avoid, and if you try to avoid it, you stick out. The correct maneuver is to appear normal, but selectively shutdown the system. Turn your phone on airplane and pay with cash with the moment is right. We live in a panopticon afterall.
In a country with the rule of law like the USA, the government can know you committed a crime, you know you committed a crime, society may suspect you of committing a crime, but criminal law requires a jury to convict beyond reasonable doubt. With a good lawyer this is a very tough bar, it's how organized crime gets away with so much (and despite the mafia being out of the news, they operate extremely well to this day).
So selectively you choose when to be anonymous. You pick your battles.
As a practical matter that may help the average HN normie, if you have a family you likely have life insurance. Never, ever, buy alcohol, marijuana, or cigarette / vapes / nicotine products with a credit card. Always pay cash. If you die the insurance company will go through everything to try and deny.
In the reverse case, the modern day can help you. If you drive, get a dashcam. You don't have to reveal video if you are at fault. But if not at fault, the video is gold. Put cameras around your house.
If you have rental property attached to your primary domicile, never have the internet under your own primary internet, lest you give reason for a wayward tenant to cause a search of your own home.
You aren't protecting yourself for the 99.99% time, you are prepared for the 0.01% case
ok but -- combined with innate hostility or rampant selfishness, this degenerates into the famous "low trust society" fairly quickly. Certainly there is room for work on fair courts and laws somehow? in the daylight?
They're an absolute pain in the rear to deal with, because they're self igniting, and it propagates between cells.
Your typical lithium 18650 - vape cell, old laptop cell, whatever you know it as (18mm diameter, 65mm length, cylindrical), has a high end capacity of around 3500mAh - so 3.5Ah (amp-hours - so will take an hour to drain at 3.5 amps, 3.5 hours to drain at 1 amp, handwave goes here). At 3.7V nominal, that's around 13 Wh (watt-hours, a measure of energy capacity).
As a first order handwave, when a cell runs away and burns off all the materials in it (electrolyte, plastic separators, etc), you'll get about twice the energy out of the cell as the electrical capacity - so, ballpark, 25Wh for a fully charged 18650 running away. Except, it doesn't run away in an hour. It runs away in about 30 seconds, so doing the math on that, you end up with about 3000 watts for those 30 seconds. That, meanwhile, can heat nearby cells up enough to cause them to enter thermal runaway, and the whole pack will just go, until cooled sufficiently.
"Dumping a lot of water on the pack" will, generally, cool it down enough to stop this. Assuming you can get the water where it needs to be, and in something like a shipping container battery, that's far from given.
At this point, you've got a damaged battery, in unknown condition, with none of the existing current paths able to be relied on, and probably new current paths that may or may not exist yet (water, metal, corrosion, and those paths are often high resistance and slow to form, which creates a lot of heat). It's not really safe to disassemble it or work on it until things have been discharged, because if the pack has energy left in it, it's prone to do exactly what this article talks about - reignite, later, inconveniently.
As far as disassembling it, would you go work in a few megawatt-hours of energy, in unknown configuration, with the state of the safety systems unknown, in a charred environment of unknown toxins (what you get out of a runaway is far from predictable, beyond "generally unfriendly to humans")?
It sounds silly, but if the pack is confined and the fire isn't going to spread to other packs nearby (which is why they tend to be quite spread out), the safest thing to do really is to let it burn to completion. At that point, if it's actually burned out, there's no energy left in the cells to do anything terribly nasty, and you've burned off most of the electrolyte and such.
Anyway, the right answer is lithium iron phosphate for grid scale energy storage, but even those can catch fire if water gets in the wrong places, and they will, with enough prodding, burn.
Yeah I get they're a complete nightmare to deal with because they're self oxidizing it just feels like we should have a better solution post fire than letting it sit and hope it doesn't reignite since they're so important and wide spread in our world.
> I treat it now more like advice from a friend. Great information that isn't necessarily right and often wrong without having any idea it is wrong.
"Drunken uncle at a bar, known for spinning tales, and a master BSer who hustled his way through college in assorted pool halls" is my personal model of it. Often right, or nearly so. Frequently wrong. Sometimes has made things up on the spot. Absolutely zero ability to tell which it is, from the conversation.
> ...especially when someone is particularly passionate about them.
The engineer-type brain is very much prone to "... in order to prove we can," as opposed to "Because we should. Or because this is useful. Or because this even does the job claimed."
Across a range of fields. A/B testing "engagement hacks" falls into this category, as far as I'm concerned. It was certainly successful at the stated goals.
When the project started a Mach 3 strategic bomber that out of the reach of surface to air missiles, and that could hit multiple targets on its way, was a huge advantage. It was obsoleted by ICBMs and better antiaircraft weapons, but it was still a hugely successful development program. It just didn’t provide a useful plane, but helped develop all the parts for future ones.
That era of aviation was nuts. I wish I was around for it. Men with slide rules working out the limits of material science, aerodynamics, and everything else, all at once. Because it wasn't enough to just push one limit, you had to push half a dozen others to get things to that first limit. And the rate of advance was just staggering.
The XB70 flew in late 1964. Concorde was doing revenue flights in 1976, cruising at Mach 2, with passengers being served luxury food.
> The Air Force learned that pushing the technological envelope resulted in plane that was difficult to build, difficult to maintain, difficult to fly, and perhaps even more importantly, was incredibly expensive; the program cost nearly 1.5 billion dollars, or around 11 million dollars per flight.
And nothing has changed. Pushing the limits is expensive. Always has been, always will be.
My favorite bit of design from this era went something like this: "ooohhh, we need something that can handle high heat. How about if we made it radioactive?" and so Mag-Thor was born (https://en.wikipedia.org/wiki/Mag-Thor): Magnesium plus Thorium. It's creep resistant up to 350C! And it's only mildly radioactive! That's not a problem, right?
Actually used on the BOMARC and D-21's ramjet engines- which is why you don't originals of their engines on display anywhere.
Mag-Thor is interesting it actually has rather poor overall thermal characteristic compared to most metals since its melting point is only circa 650c pretty much the same as magnesium but it basically shrugs any heat upto 350-400c depending on the alloy so it doesn’t changes its dimensions or becomes susceptible to mechanical deformation (it’s basically as hard at 350c at it is at room temp).
So it’s useful but only for very specific applications unlike say titanium. And today we have super alloys like inconel which can hold back heat creep up to 650c and it’s annealing starts at almost 900c.
Per Wikipedia, the XB70 carried: 300,000 pounds (140,000 kg) / 46,745 US gal (38,923 imp gal; 176,950 L), on a maximum takeoff weight of 542,000 lb - so about 55% of takeoff weight was fuel.
A 747-8I carries up to 63,034 gallons, or about 400k pounds, on a max takeoff weight of 987,000 pounds, or about 42% of takeoff weight.
Interestingly, the ranges are about the same. The XB70's combat radius (there and back) is 3,725 nm, for a straight line range of 7450 nm, the 747-8I's range is 7730 nm.
High altitude supersonic flight is actually fairly efficient... if you can handle it.
Was the XB-70 capable of inflight refueling? On a quick look, I can’t tell if that was the plan, or if it was going to be a one-way trip (optimistically landing in Turkey or something to refuel, but realistically…).
I don't believe it was capable of it, which is why it was so massive. The SR-71, which required inflight refueling repeatedly, only held 80k pounds of fuel (about 12k gallons). I don't have any good sense of fuel burn vs speed either, but in general, jets like to run high and fast. The old Lear 23s burned about as much fuel (pounds per hour) idling on the ground as they did at cruise, and I think the SR-71 (which mostly used the turbojets to keep the afterburners lit, at cruise...) fuel economy up high was quite good. Apparently the major problem with performance was keeping it from overspeeding - left to their own devices, the engine (... entire engine assembly, however long it was) was running so efficiently that they just wanted to go.
The actually built XB-70's- the two prototypes- did not have a refueling receptacle. Production models would have had a boom receptacle just like the B-47, B-52 and B-58 did. It would have gone in the upper fuselage about where the delta wing starts.
