Your Nations Warships, MKII

[Lamoni]

How are current OTHR beams steered?

According to this: http://www.dtic.mil/dtic/tr/fulltext/u2/a261727.pdf

Beam steering is achieved, for the OTH radar, by adding a linearly increasing phase
delay to the digitized output of each receiving element of the array as a function of
the distance each element is from the end of the array. Since the signals out of the
elemental receivers are stored in the computer, different steer directions can be
accomplished at the same time. In fact, three receive beams spaced 5' apart are
generated for each steered position of the 7.5' transmit beam. This speeds the
scanning time of the radar by a factor of three but at the expense of increased
processing capability, i.e., to be able to process the signals from the three adjacent beams simultaneously. Boresight, for the "broad side" arrays used in the OTH-B
radar systems, is the direction perpendicular to the axis of the linear array. The
above equation shows that as the array aperture (total length of the array) Nd,
increases, the half power beamwidth decreases.

[Triplebaconation]

How are current OTHR beams steered?

According to this: http://www.dtic.mil/dtic/tr/fulltext/u2/a261727.pdf

Beam steering is achieved, for the OTH radar, by adding a linearly increasing phase
delay to the digitized output of each receiving element of the array as a function of
the distance each element is from the end of the array. Since the signals out of the
elemental receivers are stored in the computer, different steer directions can be
accomplished at the same time. In fact, three receive beams spaced 5' apart are
generated for each steered position of the 7.5' transmit beam. This speeds the
scanning time of the radar by a factor of three but at the expense of increased
processing capability, i.e., to be able to process the signals from the three adjacent beams simultaneously. Boresight, for the "broad side" arrays used in the OTH-B
radar systems, is the direction perpendicular to the axis of the linear array. The
above equation shows that as the array aperture (total length of the array) Nd,
increases, the half power beamwidth decreases.

It was a rhetorical question. OTHR beams are steered electronically.

[Lamoni]

According to this: http://www.dtic.mil/dtic/tr/fulltext/u2/a261727.pdf

It was a rhetorical question. OTHR beams are steered electronically.

I posted that, because I didn't think that everyone knew that.

[United Allied Earth Federation]

I'm just gonna ask maybe a very stupid question, but would it be practical to put a uninsulated nuclear reactor on a ship about the size of a battleship? Obviously the ship would have to be unmanned but I was looking for other problems than that.

[Triplebaconation]

It was a rhetorical question. OTHR beams are steered electronically.

I posted that, because I didn't think that everyone knew that.

It should be obvious - the antennas are stationary.

Full details can be found in Fabrizio. Kolosov is good and readily available, but less comprehensive. Lyras is just making stuff up to justify Isselmere's ship.

[Lyras]

The point I was making is that its easier with three arms of antennas than with six. Fewer variables. But you know that, TBN. I have long argued that its doable, and whenever I explain how any particular element fits the criteria, the goalposts shift.

Its getting highly irritating.

[Triplebaconation]

The goalposts shift because you're making stuff up as you go along.

"It's also not electronically steered," and "land-based systems sprawl at least partly because it makes maintenance easier, and saves the computational pain-in-the-arse that is doing beam guidance electronically" becomes it's easier with three arms than six when Lamoni contradicts you. I don't even know where the goalposts are anymore.

[Lyras]

TBN, when we explain something for the purpose of establishing that its doable according to conventional technology and collective humanity's knowledge, for use in this text-based roleplay game, there's only so far I/we are going to go.

TLDR: A big enough ship can mount an OTH radar, co-locating transmitter and receiver.

[Yukonastan]

TBN, when we explain something for the purpose of establishing that its doable according to conventional technology and collective humanity's knowledge, for use in this text-based roleplay game, there's only so far I/we are going to go.

TLDR: A big enough ship can mount an OTH radar, co-locating transmitter and receiver.

How big is big enough?

As an example, Duga-3's transmitter array is about 60 metres wide, and 770 metres long. Main array 450 metres.

It has an ionospheric measuring station colocated, about 1750 metres to the southeast.

The receiver, located no less than about 57500 metres northwest, would make any self-contained OTH ship with a range and capability similar to Duga-3 impossible. Since you'd need a ship sixty kilometres long, and we've established problems with ships one sixtieth of said length. The longest existing ship is 488 metres long, MAYBE enough to fit the main array of the Duga-3 on. Then we need to remember that said transmitter had 10MWe isotropic radiated power. That requires a fairly large power plant in the ship. While the largest Wartsila is capable of providing eight times that power on the shaft, you have to take into account that that power also goes toward making the ship move.

You won't colocate transmitter and receiver. Not reasonably.

[Triplebaconation]

TBN, when we explain something for the purpose of establishing that its doable according to conventional technology and collective humanity's knowledge, for use in this text-based roleplay game, there's only so far I/we are going to go.

TLDR: A big enough ship can mount an OTH radar, co-locating transmitter and receiver.

How big is big enough?

As an example, Duga-3's transmitter array is about 60 metres wide, and 770 metres long. Main array 450 metres.

It has an ionospheric measuring station colocated, about 1750 metres to the southeast.

The receiver, located no less than about 57500 metres northwest, would make any self-contained OTH ship with a range and capability similar to Duga-3 impossible. Since you'd need a ship sixty kilometres long, and we've established problems with ships one sixtieth of said length. The longest existing ship is 488 metres long, MAYBE enough to fit the main array of the Duga-3 on. Then we need to remember that said transmitter had 10MWe isotropic radiated power. That requires a fairly large power plant in the ship. While the largest Wartsila is capable of providing eight times that power on the shaft, you have to take into account that that power also goes toward making the ship move.

You won't colocate transmitter and receiver. Not reasonably.

This kind of argument by analogy is responsible for the Longsword in the first place. It's far better to understand at least the basic principles.

The Longsword was originally designed to shoot lots of missiles. When it was pointed out how inefficient it was, the OTHR was emphasized. People that used to it shoot lots of missiles were "using it incorrectly." But since the OTHR was originally just a throwaway line in a statblock, Lyras can't give hard information. Q: "Just where is the antenna exactly???" A: "There's only so far I/we are going to go. TLDR; It works because I say it does."

[Yukonastan]

I'm just gonna ask maybe a very stupid question, but would it be practical to put a uninsulated nuclear reactor on a ship about the size of a battleship? Obviously the ship would have to be unmanned but I was looking for other problems than that.

While this was for an aerospace project, it should be fairly clear why it can't be expected to be practical in any way.

---

*snip*

You won't colocate transmitter and receiver. Not reasonably.

This kind of argument by analogy is responsible for the Longsword in the first place. It's far better to understand at least the basic principles.

Point is, a fairly large OTH array still requires a vast ship. It'd be the tallest modern ship ever, at the very least. The longest too. To recap, longest ship
Then there's synchronisation between transmitter and receiver, which are separate ships about sixty kilometres apart. Doable, but fairly difficult.
Along with that comes the fact that ships supporting OTH arrays have to be at anchor to make the most use of 'em.

In regards to the Onera NOSTRADAMUS: Good luck fitting that on anything less than a massive drilling rig.

From what I've been able to find, 288 antennas, for 96 per arm, for three star arms, at 120º offset angles. From quick measurements, I found that each arm is around 350 metres long. About 670 metres side length for an equilateral triangle.

That'd be a platform larger than the largest ship.

Largest oil rig at this time is the Berkut oil rig, 100x133 metres. You'll need a vastly bigger oil rig, I'm afraid.

[Lyras]

We've established that Nostradamus co-locates transmitters and receivers, proving concept. I'm sure I just indicated this.

[Triplebaconation]

Where is the antenna array?

[The Predator Federation]

Here, my factbook
http://www.nationstates.net/nation=the_ ... /id=252737
*Drops it on table*

[Yukonastan]

Where is the antenna array?

I posted coordinates for the Nostradamus array over on the realism thread. Beware that they're VERY hard to see on google maps, because they're so thin.

This marks the site's location better, it's that sandy cross. Co-ordinates are at the exact centre of that cross, if you check the realism thread.

[Triplebaconation]

Where is the antenna array?

I posted coordinates for the Nostradamus array over on the realism thread. Beware that they're VERY hard to see on google maps, because they're so thin.

This marks the site's location better, it's that sandy cross. Co-ordinates are at the exact centre of that cross, if you check the realism thread.

What exactly does this have to do with the Longsword?

It's a very basic question about the ship, and one that's never been answered. Where is the antenna?

[The Predator Federation]

How many ASMs does it take to take down a ship?

[Yukonastan]

I posted coordinates for the Nostradamus array over on the realism thread. Beware that they're VERY hard to see on google maps, because they're so thin.
(Image)
This marks the site's location better, it's that sandy cross. Co-ordinates are at the exact centre of that cross, if you check the realism thread.

What exactly does this have to do with the Longsword?

It's a very basic question about the ship, and one that's never been answered. Where is the antenna?

Longsword's an OTH carrier (apparently) so I share your confusion about the antenna being invisible.

Considering that the Longsword apparently uses a colocated transmitter/receiver installation, Nostradamus is the most similar.

[The Predator Federation]

I posted coordinates for the Nostradamus array over on the realism thread. Beware that they're VERY hard to see on google maps, because they're so thin.

This marks the site's location better, it's that sandy cross. Co-ordinates are at the exact centre of that cross, if you check the realism thread.

What exactly does this have to do with the Longsword?

It's a very basic question about the ship, and one that's never been answered. Where is the antenna?

Ooh can I guess? Uh.. is it a SPQ Radar?

[The Predator Federation]

Can your ships fit AH-1Zs or KA-52Ks?

[Yukonastan]

What exactly does this have to do with the Longsword?

It's a very basic question about the ship, and one that's never been answered. Where is the antenna?

Ooh can I guess? Uh.. is it a SPQ Radar?

Wrong. It's an OTH radar.

As for AShMs required to take out a ship, HMS Sheffield was struck by a single Exocet which didn't even explode.
She did take six says before she sank, however.

[The Predator Federation]

Ooh can I guess? Uh.. is it a SPQ Radar?

Wrong. It's an OTH radar.

As for AShMs required to take out a ship, HMS Sheffield was struck by a single Exocet which didn't even explode.
She did take six says before she sank, however.

Lessons from the falklands war I see.
The sea apache would have been a ships terror but it was cancelled. Oh well AH-1Zs or in Russian ventures, KA-52Ks can do the job.
Or an F/A-18E carrying AGM-84s.

[Lyras]

Amidships, behind the bridge. Lineart needs work, but thats another matter. Will update it some stage.

[Triplebaconation]

So less than 200m in diameter now that it's a circular array?

[Connori Pilgrims]

How many ASMs does it take to take down a ship?

That would depend on the type of ship, the type of missile, where in the ship you hit it, and how bad/good damage control is.

During Operation Praying Mantis 1988, the Iranian frigate Sahand took 3 Harpoons, 4 Skippers, a Walleye and some 1000lb-er bombs. Crippled and damaged and listing, but did not go down until the resultant fires hit the magazines causing it to blow up.

More recently, the Israeli corvette Hanit got hit by a C-802 missile which AFAIK did blow up, but survived and was repaired.

The sea apache would have been a ships terror but it was cancelled. Oh well AH-1Zs or in Russian ventures, KA-52Ks can do the job.

Unless those ATGMs they carry can cause fires or hit an ammo magazine, nope they wont be much of a terror. Hell that assumes they can even get close to a modern warship with the proper SAMs before they get pasted out of the sky giving the ship free kills.

F-18s with proper AShMs have a far far better chance of success.