OVERVIEW: The GBU-31(V)2/B Joint Direct Attack Munition (JDAM) is an inertial guided, GPS-aided, glide bomb using a bolt-on guidance and aerodynamic package mated to a Mk 84 (428 kg HE) bomb.

DETAILS: JDAM is intended to provide accurate delivery of general purpose bombs in adverse weather conditions. 

Before take off, mission plans including release envelope, target coordinates and weapon terminal parameters are loaded to the host aircraft prior to take off.  Before release,   INS alignment and targeting data and is automatically loaded to the weapon. 

The JDAM is a "fire-and-forget" weapon system.  Once released, the bomb's INS/GPS guides the bomb to the target, allowing the launching aircraft to take evasive action without having to guide the weapon.  The INS is capable of guiding the JDAM to target independently of the GPS, albeit at a reduced accuracy.  This gives the JDAM the capability of operating even in a high-jamming environment.

The JDAM can be launched from very low to very high altitude and can be launched in a dive, toss, loft or in straight and level flight with an on-axis.  Off-axis delivery is also possible, albeit with a decrease in bomb range. JDAM also allows multiple target engagements on a single pass delivery.


Specifications: 

Weight: 		925kg
Length: 		3.879m
Wingspan:		0.635m
Speed:			 knts 
Range:			13.0 nm (altitude dependant)
Accuracy:		CEP: 30 meters w/o GPS; 13 m with GPS and INS

NOTES:  IOC 1997. Officially, the GPS-enhanced CEP of the weapon is cited as 13 meters.  However, according to Jane's, accuracy is reportedly approximately 14 meters (INS only) and 8 meters (INS+GPS).  The visible difference between the USAF's GBU-31(V)1/B and the Navy's GBU-31(V)2/B is that the USN MK 84 and BLU-117A/B bombs are coated with a thermal protection layer, giving the bombs a wrinkled grey external finish, opposed to the USAF's smooth olive drab bomb bodies.
 
 
SOURCES: IHS. "GBU-31, GBU-32 and GBU-38 Joint Direct Attack Munition (JDAM)." Jane's Air-Launched Weapons, Feburary 2015;  "Joint Direct Attack Munition (JDAM) GBU-31 - Smart Weapons." Federation Of American Scientists. Accessed December 29, 2019. https://fas.org/man/dod-101/sys/smart/jdam.htm; 
Pike, John. "GBU-31 Joint Direct Attack Munition (JDAM)." GlobalSecurity.org. Last modified June 12, 2017. https://www.globalsecurity.org/military/systems/munitions/gbu-31.htm;  "Boeing JDAM." Designation-Systems.Net. Last modified August 21, 2008. http://www.designation-systems.net/dusrm/app5/jdam.html.