IAM & GPS/INS

[jeproject]

In the simulation are IAM & GPS/INS weapons the same thing?

 

It mentions both in the manual however it doesn't seem to differentiate their use. I am still reading through the manual so I may have missed something but I just wanted to clarify this.

 

Wikipedia's information really just groups all the JDAM weapons into one page and trying to get further info on the specific weapons gives more info on the basic dumb bomb rather than the guidance portion.

 

Edit : Link explaining how JDAM works: http://science.howstuffworks.com/smart-bomb2.htm

Edited November 9, 2013 by jeproject
Added link

[Flagrum]

In the simulation are IAM & GPS/INS weapons the same thing?

 

It mentions both in the manual however it doesn't seem to differentiate their use. I am still reading through the manual so I may have missed something but I just wanted to clarify this.

 

Wikipedia's information really just groups all the JDAM weapons into one page and trying to get further info on the specific weapons gives more info on the basic dumb bomb rather than the guidance portion.

Afaik: IAM knows where it is (coordinates of the aircraft when released) and knows where it has to go (target coordinates). While on the go, it can not check if the current position is still correct (i.e. wind drift!).

GPS/INS: like IAM, but has the ability to update its current position by means of GPS and thus able to correct errors like wind drift or suboptimal release parameters.

[Eddie]

They are, as you suspected, two terms for exactly the same thing.

 

JDAMs and WCMDs are both types of IAMs.

[Flagrum]

They are, as you suspected, two terms for exactly the same thing.

 

JDAMs and WCMDs are both types of IAMs.

But in terms of guidance, JDAMs and WCMDs are not equivallent? At least not for those we have in DCS?

[jeproject]

The term IAM seems odd to me as without the GPS aspect it is not going to work. I like the term GPS/INS better.

 

I always assumed GPS guided weapons merely checked their own GPS coordinates versus the targets until they matched though. I never realized all the other gyro/accel sensors were used too. Are these as backup in case it loses signal with the satellite?

[Eddie]

The term IAM seems odd to me as without the GPS aspect it is not going to work. I like the term GPS/INS better.

 

It most certainly will.

 

I always assumed GPS guided weapons merely checked their own GPS coordinates versus the targets until they matched though. I never realized all the other gyro/accel sensors were used too. Are these as backup in case it loses signal with the satellite?

 

The INS is the primary guidance system. Just as in the A-10C itself (any any other military aircraft for that matter) all the GPS system does is provide position updates to the INS to correct for gyroscopic drift errors.

 

It takes at least 10 seconds from release for JDAM to acquire a valid 3d GPS position. If the time of flight is any less than that, or if GPS jamming is in operation, the weapon guides to the target solely using the INS.

 

WCMD is INS only and does not have any GPS assistance.

[jeproject]

It most certainly will.

 

 

 

The INS is the primary guidance system. Just as in the A-10C itself (any any other military aircraft for that matter) all the GPS system does is provide position updates to the INS to correct for gyroscopic drift errors.

 

It takes at least 10 second from release for JDAM to acquire a valid 3d GPS position. If the time of flight is any less than that, or if GPS jamming is in operation, weapon guides to the target solely using the INS.

 

WCMD is INS only and does not have any GPS assistance.

 

That's really interesting thanks. So all the hype about GPS targeting was a mostly just that then, hype. The inertial systems were already in place and the GPS was just icing on the cake. I wonder how many JDAMs hit their target before they even latch onto a sat signal.

[amollen]

That's really interesting thanks. So all the hype about GPS targeting was a mostly just that then, hype. The inertial systems were already in place and the GPS was just icing on the cake. I wonder how many JDAMs hit their target before they even latch onto a sat signal.

 

Well.... GPS is not all hype. INS position drifts over time and GPS "corrects" the INS position. I don't know about military INS-es, but for instance the "old" 747-200 airliners that had INS without GPS could be 5-10 miles off-course after a trans Atlantic crossing. Once they get to the other side of the ocean they could correct the INS by measuring a position off a VOR-DME.

 

A drift of a mile per hour is OK if you have 747s in wide airways but not if you're dropping a bomb on a bridge through an overcast cloud deck :music_whistling: