Harpoon – Land Attack out of the box?

The GPS signal in JASSM was dropping out as you well know (or should know), due to evasive manoeuvres the missile was required to conduct in the terminal phase.

Whether Harpoon Block II is required to conduct such evasive manoeuvres or not is a matter of debate.

What is not debatable is whether or no it possesses a “land attack” capability.

JDAM does.

Clearly Harpoon Block II does, too…

It also had to do with the nature of the missile itself. JASSM is a stealthy missile where Harpoon is not. That means the GPS antenna on JASSM is likely in some funky configuration to mask it from most angles (consequently making in blind from most angles) whereas the antenna on Harpoon could be optimized for clear reception regardless of the angle.

There is an upgrade kit being marketed for the Harpoon that gives it some land attack ability vs. fixed land targets. One must assume that this would include all the software to fly those kinds of missions. This is one of the reasons Israel was complaining of more marketing efforts of the Harpoon to Egypt not too long ago.

In order for something like this to be truly effective over long range it would need datalinking to back up GPS updating of the INS not unlike JASSM or Tomahawk IV. If the GPS signal was inhibited somehow over such a long range there is a big risk of the INS not being refreshed enough and therefore not being able to give you a useful CEP. A problem brought forward in JASSM tests in 2007. Of course if money is of no object there is always the option of backing up GPS for cruise missiles by giving them back route-terrain matching like early cruise missiles, or even star trackers.

The GPS signal in JASSM was dropping out as you well know (or should know), due to evasive manoeuvres the missile was required to conduct in the terminal phase.

Whether Harpoon Block II is required to conduct such evasive manoeuvres or not is a matter of debate.

What is not debatable is whether or no it possesses a “land attack” capability.

JDAM does.

Clearly Harpoon Block II does, too…

AFAIK U/RGM-84G Harpoon’s have land attack capability to a certain degree (i.e shore targets etc) by assigning waypoints through the fire control system.

There is an upgrade kit being marketed for the Harpoon that gives it some land attack ability vs. fixed land targets. One must assume that this would include all the software to fly those kinds of missions. This is one of the reasons Israel was complaining of more marketing efforts of the Harpoon to Egypt not too long ago.

In order for something like this to be truly effective over long range it would need datalinking to back up GPS updating of the INS not unlike JASSM or Tomahawk IV. If the GPS signal was inhibited somehow over such a long range there is a big risk of the INS not being refreshed enough and therefore not being able to give you a useful CEP. A problem brought forward in JASSM tests in 2007. Of course if money is of no object there is always the option of backing up GPS for cruise missiles by giving them back route-terrain matching like early cruise missiles, or even star trackers.

A simple question I am sure someone in this forum can answer…Does the AGM-84 Harpoon ASM have a land attack capability out of the box?

You mean the RGM version? Sea-SLAM was looked into but not realized.
The Navy does not promote things competing with their carrier-based aviation.

Not unless the flight systems are reprogrammed for it in the form of a land attack mode. An AshM is programmed to fly in a very different profile—intended to skim only a few meters off the surface using its altimeter and radar to read the water surface. For land attack it has to fly higher to clear obstacles, and the radar must be reading the terrain and responding to it. The radar has to compensate for the ground clutter, which is different from sea clutter which naval radars are compensated for. You might like the missile to have some form of set cruise altitude, which has to be higher in the case here rather than the cruise altitude of an antiship missile. Doable if you want to do it but it would add a lot of bucks to the cost of the missile. Not likely on an export model that is facing a price requirement.

AGM-84L is a GPS-equipped Harpoon Block II, offered for export. Requested in 2008 by Taiwan as the UGM-84L sub-launched version.
http://www.scramble.nl/wiki/index.php?title=Harpoon#AGM-84L

AGM-84L Essentially a Block 1C missile with GPS guidance to improve accuracy on the approach vector. It was an export model only, not used by the US
RGM-84L As per AGM-84L
http://middle-watch.com/Harpoon.htm

Crobato: since this version is GPS equipped, could it be used for landattack?

A simple question I am sure someone in this forum can answer…Does the AGM-84 Harpoon ASM have a land attack capability out of the box?

No. If a Harpoon is made for land attack, the seeker has to change, preferably to an electro-optical one that relies on optical contrast and pattern recognition. Active radar guidance, like what ships use, blows when it comes to land attack because of terrain irregularities and obstructions, unlike the sea, which is essentially flat. So everything reflects radar on the ground. Against the sea, you got specular wave reflections but that can be differentiated from the reflection of a solid object. The radar seeker on an antiship missile is optimized against the backscatter of the ocean surface, but not against a solid ground. As a matter of fact, antiship missiles also have problems dealing with targets near the coast due to the radar reflections from the floor of the shallow water, as well as various coastal rocks. Coastal antiship missiles are either thermal or TV-optical guided.

Sea skimming antiship missiles will also take a very low flight profile, using radar like an altimeter. That’s going to depend a lot how the radar deals with scatter, and scatter over ground are different from water. During its initial and midphase, an antiship missile also receives target updates. A cruise missile uses radar differently. It scans the surface using doppler sharpening, then compares the features with a map stored in its memory. A sea skimmer does not have terrain maps stored in its memory, the radar does not terrain map, nor does it has the capacity to store a radar image of the target. An antiship missile in principle works much closer to an active radar guided BVRAAM missile than a cruise missile despite the physical resemblance.

SLAM and SLAM-ER are basically Harpoons with the seekers and midphase guidance systems changed, basically to TV guided ones or digital infrared imaging. These kinds of missiles can send TV images of their targets back to their launch planes or ships, which the operators can identify, target and authorize. So they’re closer in principle to Mavericks on steroids.

Land-attack capability was originally developed for the Block II missile, but is probably available on late-model Block IG missiles, since these use the same guidance hardware as the Block II.

Depends on the version, newer variants (particularly for export to nations that have no hope of being cleared for Tomahawks) do. And then there’s always the SLAM-ER, as an airlaunched derivative:

http://www.designation-systems.net/dusrm/m-84.html