Articles: "Nuclear Warfare 101".

[Beowulf]

A caveat: false color is only as good as the sensor that the false color data came from. The advantage isn't so much the false color itself as that it lets a human user take full advantage of the resolution of the sensor. We can tell which of two colors is "more red" or "more blue" with much greater precision than we can tell which of two light sources is "more bright."

So the advantage of false color is that it lets us take raw data from a machine (any machine) and translate it into a form a human can use more efficiently than they could use a black and white image or a huge mass of numbers.

I use false color imagery every day. Essentially every weatherman will use it as some point. It's essentially impossible to use grayscale IR imagery for meteorological forecasting, because you can't tell the difference between 0C and -30C by eye on a grayscale image, but it's really easy on a colorized image.

[Simon_Jester]

A caveat: false color is only as good as the sensor that the false color data came from. The advantage isn't so much the false color itself as that it lets a human user take full advantage of the resolution of the sensor. We can tell which of two colors is "more red" or "more blue" with much greater precision than we can tell which of two light sources is "more bright."

So the advantage of false color is that it lets us take raw data from a machine (any machine) and translate it into a form a human can use more efficiently than they could use a black and white image or a huge mass of numbers.

I use false color imagery every day. Essentially every weatherman will use it as some point. It's essentially impossible to use grayscale IR imagery for meteorological forecasting, because you can't tell the difference between 0C and -30C by eye on a grayscale image, but it's really easy on a colorized image.

Yeah. As I said, planetary scientists do it too, for much the same reasons, only often with a much wackier range of possible subjects for the false-color. I've seen pictures of Mercury (which looks a lot like the moon in real life) covered in blues and oranges because of a false-color map of surface composition.

And then of course there are all those Hubble photos; pretty much everything that gets released to the public is false-color.

[Steel]

Also, concerning skin friction giving away stealth aircraft to IRSTs/FLIRs. Composites help a little, but is there any research being done into active cooling systems to counter that issue? (Sort of like how the F-4 used engine exhaust forced over flaps to increase their effectiveness.)

I don't think it can physically be done. The heat has to come out somewhere ; You can shuffle it around, but you have to dump it eventually. You can radiate it through the skin, or use tricks and heat pumps to move it somewhere else, like a radiator in a specific place, maybe the exhaust, etc, which means the enemy will have to release a programming patch for their infrared sensors to recognize the new B2 heat signature.

Spacecraft do it a lot, actually, but it doesn't mean the Space Shuttle is invisible on infrared ; It just has huge glowing radiator flaps.

I was thinking perhaps having the waste heat be vented through the turbine exhaust, that way it can be cooled again as the platypus nozzles absorb some of the heat. I'm not expecting total stealth from IR, but any range you can shave off an enemy fighter's effective IRST range is progress.

Conservation of energy guarantees that if your engines are producing X watts of power (both useful energy and waste due to innefficiency) then you are radiating X watts of power as heat*.

Basically your only choices are how you disperse this heat. You can try and pump is out over a larger volume by diluting the exhaust gases with cooler air from outside, but you still released the same quantity of energy. You could try and stuff big radiators on the back so that the majority of the heat goes out the back rather than the front, which makes you less visible from one aspect, but much more visible from another. Another problem is if you put out too much heat in one place then the heated patch of air is going to be just as visible as your warm nose would be.

What you'll end up doing is trying to minimise the maximum temperature visible from a given direction. You can't reduce the total amount of heat you put out in the long term.

*in the steady state at least- you may briefly not be radiating the same amount of power that you are producing, in that case you are either accelerating, getting hotter or exploding, however none of those states last very long.

As for 'false sound' what is an alarm? Its already used, just in a slightly more abstract sense than for false colour. There isn't really any difference between a totally arbitrary mapping from temperature to say a rainbow colour spectrum for thermal imaging than there is from a discrete set of threats to a bunch of different sounding horns.

[PeZook]

Color of space imagery is a fascinating subject in and of itself, since most instrumentation on probes and the like is not like commercial cameras. For example, take pictures from Mars: on some, the is blue, on others red, yet others have it orange. That's because every picture from all probes ever was taken using several different filters and is usually a composite built to provide science, rather than just pretty thingies.

It can be pretty cool tracking down the precise data about the picture and then finding out what tremendous amount of information it provides beyond "huh, some rocks here", if you just know what parts of the spectrum it was taken in.

Check this out for an example of what I am talking about. It's just a pretty picture until you learn that red represents a giant plume of hydrogen, while blue indicated dust. Suddendly, we can tell a lot about the star...

Of course, conspiracy nuts have no understanding of it at all, and thus conclude that NASA is deliberately mucking about with colors on their pictures for some unknown, but doubtlessly sinister purpose

As for 'false sound' what is an alarm? Its already used, just in a slightly more abstract sense than for false colour. There isn't really any difference between a totally arbitrary mapping from temperature to say a rainbow colour spectrum for thermal imaging than there is from a discrete set of threats to a bunch of different sounding horns.

Some space docking radar use (or used to use, I'm not sure how it works on the Shuttle, for example) a series of bleeps to roughly indicate range from target: the faster the bleeps go, the closer you are.

Noise on spacecraft is mostly a problem, though, rather than an aid, so measures are taken to minimize it, since it's often totally counterproductive in space. It has an annoying tendency to make it more difficult to talk to mission control

[Stuart]

Speaking of False Color, it it possible that NASA or some other space program creates False Sound? We all know that there is no sound in space because of a lack of medium, it would seem that a good use of computing power would be to generate sound for the Crew/Pilot to increase situational awareness.

To some extent this is already done. "Synthetic sound" is added to the environment to make sure that audio cues aren't missed. Another way of approaching this is "active sound cancellation". This works by sensors detecting emitted sound and then creating a sound wave that is 180 degrees out of phase so that it cancels the sound completely. This is used in armored vehicles for example, to protect the crew's hearing when the main gun is fired or the diesel revs up to maximum power. I've worn the earphones used for active noise cancellation equipment (Bose is a major player here) and the difference is remarkable.

However, the primary user of active noise cancellation is the submarine fleet. basically the submarine has external sensors to monitor noise emissions and then transmits out-of-phase sound to cancel those emissions. It is rumored that submarines also transmit aquatic background noise to avoid the black hole effect. However, that is about as far as we can go there.

A PS to the above. A problem with modern cars is that their sound insulation is so good that audio cues from outside are drastically reduced. That includes warning sounds from car horns etc (on some cars its impossible to tell by sound what the engine is doing or if indeed it's running at all. One reason why I like convertibles) and that translates to a higher accident rate. "Synthetic sound" is one possible solution to that.

Also, concerning skin friction giving away stealth aircraft to IRSTs/FLIRs. Composites help a little, but is there any research being done into active cooling systems to counter that issue? (Sort of like how the F-4 used engine exhaust forced over flaps to increase their effectiveness.)

The problem is that the thermal image pattern isn't constant; it shifts according to the speed the aircraft is doing, its angle of attack, the wind direction and a host of other factors. The airframe has stagnation points and hot spots, all of which shift around as the aircraft changes speed, direction and altitude. So, any such system would have to include temperature sensors all over the aircraft's skin hooked to a central computer so the aircraft's heat image is known at a given time. Then, the cooling system would have to be applied to each area to reduce its termeprature to ambient. Now, high up, ambient temperature is very cold. At 16,000 feet the air temperature is around 1.9 degrees F, at 40,000 feet the air temperature is -67.9 degrees F. That's bitterly cold although it has its advantages. So, the amount of heat to be extracted and dumped is extreme. Remember this is a continuous process. My gut feel would be that the bulk of the system is such that it isn't practical. that may well be all wet and N-G have found a way to do it but any answers there would be deep into finger-breaking territory.

I have no doubt that a lot of work is being done on looking at reducing thermal signatures but I fear it is all very highly classified.

[PeZook]

Isn't it all going to be tricks, though, Stuart? You can't beat physics, so you will have to use funky tricks aimed more at confusing sensors rather than actually becoming invisible, and it's way easier to upgrade sensors than it is to build a new heat management system into your billion $ stealth planes.

[Stuart]

Isn't it all going to be tricks, though, Stuart? You can't beat physics, so you will have to use funky tricks aimed more at confusing sensors rather than actually becoming invisible, and it's way easier to upgrade sensors than it is to build a new heat management system into your billion $ stealth planes.

Exactly. In one neat sentence you've put your finger on the hole in the Stealth theory. It's much easier to improve sensors than to reduce signatures. Once we reach a given level of signature reduction, going further costs so much that it just isn't worth the effort. It's easier to blow up the radar station.

[PeZook]

It's easier to blow up the radar station.

Especially if you can get two or three less-stealth bombers loaded with missiles for the price of a single fully tricked out superstealth one

[Simon_Jester]

Of course, conspiracy nuts have no understanding of it at all, and thus conclude that NASA is deliberately mucking about with colors on their pictures for some unknown, but doubtlessly sinister purpose

Well, of course they are. The mucking is deliberate, and it's for a purpose that is unknown. Unknown to them, because most of them wouldn't know a spectral line if it walked up to them, jumped up and down in their face, and bit their leg off.

[Stuart]

Especially if you can get two or three less-stealth bombers loaded with missiles for the price of a single fully tricked out superstealth one

Absolutely; although the price differential is higher than that. A B-2 costs around US$2.13 billion; a Boeing 747-based missile carrier would cost around US$300 million. So, it's a choice between a single B-2 or seven missile trucks. Also, a B-2 takes 119 hours of maintenance for every flight hour (twice that of a B-1B). A 747-based missile truck would take about 40 and a B-52 missile truck around 50. Actually, I don;t much like the idea of a Boeing 747 missile truck; its just a useful reductio ad absurdam. However a C-17 based missile truck is a very attractive proposition and would cost about the same as a 747-based equivalent.

An interesting little factoid by the way. A missile truck orbiting at 14,000 feet has a radar horizon of 167 miles; in other words, if its 200 miles from the coast (or the nearest radar station) it's over the horizon and invisible to ground-based radars. Obviously AWACS changes that a bit but not as muich as one might expect. So all this stuff about firing from weird and unexpected angles isn't really very meaningful; again, its easier and cheaper to stay out to sea and dog-leg the missiles.

[Patrick Degan]

Especially if you can get two or three less-stealth bombers loaded with missiles for the price of a single fully tricked out superstealth one

Absolutely; although the price differential is higher than that. A B-2 costs around US$2.13 billion; a Boeing 747-based missile carrier would cost around US$300 million. So, it's a choice between a single B-2 or seven missile trucks. Also, a B-2 takes 119 hours of maintenance for every flight hour (twice that of a B-1B). A 747-based missile truck would take about 40 and a B-52 missile truck around 50. Actually, I don;t much like the idea of a Boeing 747 missile truck; its just a useful reductio ad absurdam. However a C-17 based missile truck is a very attractive proposition and would cost about the same as a 747-based equivalent.

As an aside, do you see this as the possible future for the U.S. strategic bombing force as defence budgets shrink and both the B-2 and B-52 reach the end of their service lives?

[Shroom Man 777]

Could it be said that the age of the bomber has gone by? Aside from America and Russia, and China with its Tu-16s, what other nation has a decent bomber force of note? If America and Russia don't bother with a next-generation bomber, does this mean that the bomber will go extinct?

[Stuart]

As an aside, do you see this as the possible future for the U.S. strategic bombing force as defence budgets shrink and both the B-2 and B-52 reach the end of their service lives?

The real problem with developing a bomber is that it takes time and costs money. If there's an administration change that's unsympathetic, then the program dies. That's why the idea of developing a bomber derivative of the C-17 is attractive. It can be done quickly (ie within the eight-year lifespan of a stable presidency) and can do both the bomb and missile truck roles. It won't be much use as a penetrator but then its not intended to be.

As for a bomber penetrator, this is possible although personally I think it won't make it. I really hope I'm wrong there.

Could it be said that the age of the bomber has gone by? Aside from America and Russia, and China with its Tu-16s, what other nation has a decent bomber force of note? If America and Russia don't bother with a next-generation bomber, does this mean that the bomber will go extinct?

The heavy bomber is really a strategic tool and very few countries have the need for them. For example India has a nuclear bomber fleet but because its targets are all short-range, they're actually fghter-bombers. China is reputed to be developing a new bomber but that's been rumored for years. The Russian Tu-160s are marvellous beasts, they've got a lot of life in them. A bright nation that wants strategic bombers would do well to buy them. That leaves the US. At the moment the Gray Lady looks like outliving both of her successors. However, when this generation goes, its quite likely the heavy bomber will be extinct.

[Starglider]

As for a bomber penetrator, this is possible although personally I think it won't make it. I really hope I'm wrong there.

That'll be a win for the US Navy then, if a Minuteman replacement also gets cancelled because 'we only have enough money for one new missile and SLBMs are more survivable / less vulnerable to ABM / able to be co-developed with the UK for their Trident replacement'. The strategic deterrent role of the USAF would be gone entirely.

[MKSheppard]

From F-22A Footage at Farnborough courtesy of Flightglobal IRST systems...

[Simon_Jester]

Bad news from the point of view of the F-22 being sneaky, but it looks awesome...

[MKSheppard]

The last photo on the bottom was taken when the F-22A was looping around; you can see how it has a huge blob of hot air trapped around it during the loop causing the bright ball of fire on IIR.

Watch the whole thing HERE