How far can large military UAV's see?

It’s easy to find a range of how much a UAV can fly (for example RQ 4 Global Hawk), but what about the “range” at which it can see? You can often see military UAV’s flying on public websites like Flightradar, since they don’t always turn off their transponders, and in a lot of cases they fly above international waters, in case of Ukraine near the frontline, but not above DNR/LNR controlled territory and so on, so how much can they actually see from those distances?

Also, how do they see, do they just have Infrared cameras or is there some sort of a ground radar that can pick up military targets? I don’t know how that second one would work, but…

The Lockheed U-2 plane could fly at 70,000 feet (21,000m) high and do standoff reconnaissance from international waters, 12 miles (22km) offshore.

This was in the late 1960’s; I would imagine the technology has greatly improved since then.

Btw, it’s not really vision range related, but it’s an interesting fact, the Global Hawk is slightly larger than most fighter jets in length and almost 3 or 4 times larger in wingspan, so although drones are usually associated with small handheld ones, these are real beasts larger than many countries fighter jets.

For the Global Hawk, the largest Air Force drone, there are several possible sensors that could be loaded on it. An advanced digital camera and a wet-film camera probably have ranges in roughly the 15 mile range. It can also carry a radar that images the ground (and the Navy variant can image the sea), with a range that’s likely closer to 30-ish miles.

I don’t know the precise range numbers, but that’s just a general ballpark.

Visual and radar horizon calculator, approximative: http://members.home.nl/7seas/radcalc.htm . Note that that’s the horizon, the maximum possible range. Whether something on the horizon actually gets detected is subject to any number of factors. A group of big curved metal objects moving fast toward the radar over open ground (like a tank unit) for an extended duration will be detected at greater range than infantry fleetingly moving through vegetation.

Airborne radar can pick up moving ground targets by their signature since at least Gulf War 1 with the E-8. A car, truck and tank have different Doppler signatures.

Pretty sure the exact details are not public.

Exact probably not, but we can eyeball them, for example the binoculars used in the military (without perhaps nightvision and all that fancy stuff) work the same way normal binoculars work, zoom level : width of lenses, for example 10:20, 12:50 and so on, there’s not a lot of other things you can add there, it all works the same, perhaps the vision on UAV’s also has a similar principle to how normal cameras or whatever work, just on a better level.

It’s not a question of zoom so much as signal-to-noise ratio. The closest analogy isn’t to binoculars but to computer graphics or the neuronal visual processing of an animal with simple vision.

Exactly right.

Range of sensors depends what resolution you need. Recon satellites are typically 100-200 miles up and often looking sideways at a significant angle through the atmosphere though not usually as obliquely as more stand off recon a/c. But their resolution, though not precisely known in public, is known to be small. Even publicly available photo’s from space can show pretty small things.

Many references describe the useful range of long range oblique camera’s even on mid Cold War recon a/c as at least 70-100 miles again depending how detailed the images had to be, besides obviously on weather conditions.

The capabilities of particular systems on particular UAV’s is often classified of course, but for the bigger sensor suites, the known performance of past recon systems implies it’s probably much more than a couple of posts above have suggested. Of course it’s less for a Raven (hand launched UAV) than a Predator presumably and more still for what you can fit into an RQ-4 Global Hawk.

On horizon calculation, one reason the USAF finally scrapped plans to ever fully replace the U-2 with the RQ-4 is the former’s 10k ft higher operational ceiling. Both a/c can certainly ‘see’ to the horizon with passive radio frequency sensors, order of 300+ miles at their operating altitudes, if that counts as ‘seeing’. And for example while the absolute effective range is classified AFAIK, a recent authoritative press article quoted Lockheed Martin’s U-2 program manager saying the ASARS-2B radar to be fitted to U-2’s doubles the effective range of the current -2A. It doesn’t seem impossible active or EO/IR sensors might also take advantage of the full horizon range from 60k (RQ-4) or 70k (U-2) ft in some cases, and that might be another reason the U-2’s higher ceiling is valued.

Here’s a Global Hawk flying near Russia, let’s say that there’s a tank somewhere on the land, how far could it see a tank from this current position, some 30-35km from the coast? https://s20.postimg.org/5caonl0yj/image.png