Originally Posted by
Coochycool
I wonder if any former/present MRA boys on here might care to comment on the following.
Helping the next door neighbour's boy with his maths homework, the following question was posed:-
A submarine at a depth of 150 feet detected an aircraft flying at a height of 30,000 feet. What is the difference in height between the two?
So simple was the answer of 30,150 feet, we suspected a trick question.
But moreover, I was left wondering at the premise of the question. I am aware that subs have acoustic capability, but can subs actually detect aircraft at such altitude from such depth?
Bearing in mind that this is a public forum
, anyone care to enlighten me on rough parameters?
I do recall once receiving nothing but a funny look upon querying a P-3 flyer on the range of his MAD boom
Cheers
Cooch
UWB Impulse SAR, mounted on an aircraft as small as a Cessna 172, can look through several hundred feet of ice and sometimes rock to find voids where there might be a P-38 or a cache` of chemicals decidedly more nasty to your health than Sulfuric Acid. It is most commonly used in FOPEN to track tanks and people.
I would not be at all surprised if modern 'periscope wake tracking' ISAR modes did not incorporate a bit of this capability as there is a suprising amount of garbage on the ocean surface, especially in the inshore littorals. None of which is 350-370ft long.
Could a similar system be made to work from beneath the waves, going the other way? You certainly would have your choice in terms of parabolic antenna area as wavelengths to operate with as the entire bow of the submarine is a 20-30ft wide dielectric fiberglass dome. The problem would be knowing the Doppler variances and range gated PRF scales likely to be occupied by a high flying ASW platform like the P-8 without losing water penetrability on the returns.
IR is another option. Da used to work for an oil company and they were using LWIR geosurvey stuff way back in the 1970s. Once, looking at an ocean map, they spotted a pair of wakes and 'doing the math' (which see: Teacher's Pet and Spherical Trig) they figured the tracks were around 800-900ft down and moving in excess of 30 knots. Parallel to each other about 20nm apart.
Not whales.
This definitely works the other way 'round too, given a buoy could mount a camera and IRST (ADADS is small enough to be manpacked) package.
The biggest problem with submarines being the emission source of anything of course is that they are sluggish and huge, to say that they turn like a truck is rather an insult to Mack. You skulk or you die.
Since dragging a tail really doesn't do much, other than increase your silent speed noise threshold, the key would seem to be to employ air dropped atmospheric sensor buoys (faster, wider, network setup) and long-line acoustic transducer networks, together with munitions carrying (missiles in box) CAPTAM mines. Leaving the SSN to play spider-in-her-web games.
Now your apertures can float which, by itself, would radically change the LOS horizon nature of submarine warfare from 1-2 CZs out to perhaps several hundred nm distant from the operational area, using point to point laser or directional microwave (possibly bent through a satellite) which would be LPI relayed back down to perhaps 1-5 master nodes which could then talk to the sub via a digital Gertrude or bluelight lidar at minimal hull risk, well outside the combat area. Even if they intercept the up and down link, nobody would know /precisely/ where the sub was.
This would indeed (IRST as much as radar) let you see an airliner at FL300 without exposing the 2 billion dollar hull to push up a mast, near the surface.
Taking the majority of sensorization and particularly heavy AShM and LAMs off the sub would, in turn, let you reduce the size of the sub to perhaps half it's present state, taking manning ratio down to say 50 or so (three shifts of CIC crews and a galley service) while employing a much smaller RTG/battery stack in a sealed motor room instead of a noisy, dangerous, steam kettle while retaining only defensive weapons with things like SCav interceptor torpedoes or possibly even 'gun' turrets to kill inbound shots. You would still likely have to escort or barrier the sub with a small 'school' of UUV, roughly the size of an ASDS. But since these robots would be cheap, they could use active sonar in sprint-drift packs to cover very large volumes of protected seaspace, kamikaziing threat subs, much farther out.
Nobody has ever sunk a sub with a DF-21D but playing stalking games with an 8,000 ton hole in the water is stupid...