OVERVIEW:  The FRONT PIECE  is a  tracker/command radar for the SS-N-3/SS-N-12 missile system for use on  surface ships.  It operates in the NATO "E/F" band.  The companion FRONT DOOR operates in the NATO F band.

DETAILS:  
The FRONT DOOR/FRONT PIECE tracker/command radar is comprised of two separate systems: the FRONT DOOR is a nodding height finder/tracking radar, and the smaller S-band FRONT PIECE is an azimuth tracking and data-link guidance antenna and is mounted on the top of the larger FRONT DOOR antenna.  After launch the SS-N-3 or SS-N-12 would climb to cruise altitude following datalink steering commands, with the missile’s position tracked by the Front Door/Front Piece radars using a beacon transponder.


Specifications:

	Frequency:	FRONT DOOR: 3-4 GHz (F-band (NATO)); FRONT PIECE: 2-4 GHz (E/F band (NATO))
	PRF:		?? Khz (air-to-air)
	Pulse width:	?? µ sec (air-to-air)
	Power: 		?? kW (peak) 
	Scan Limits:	??    
	Range:		?? nm (instrumented)
	
			
NOTES:  IOC 1958 (approx.).  The surface-ship version was initially designated TRAP DOOR.  These were subsequently redesignated as FRONT DOOR-C.  The major difference between the submarine and surface ship versions is that the submarine version folds for stowage when the submarine is submerged.



SOURCES: Friedman, The Naval Institute Guide to World Naval Weapons Systems 1997-98, pg. 336 ; Polmar, Norman and Moore, Kenneth,  Cold War Submarines: The Design and Construction of U.S. and Soviet Submarines, Potomac Books, Inc, 2014, Footnote 34; Jane's Radar and Electronic Warfare Systems 2002-03, "Front series missile guidance radars (02 July 2001); NATO, CURRENT SOVIET BLOC ELECTRONIC EWUIPMENT, Vol A: SHIPBORNE, dtd 12 Feb 1968, pg. I-B-41.  Available at https://archives.nato.int/uploads/r/nato-archives-online/7/e/7/7e7bdc7569e4f683c39b35e1e3da9fcebf56096cfd1d8f73bc80df03e6b2f014/MC_0262_A_67_FINAL_ENG_PDP.pdf ; Kopp, Dr C. "Soviet/Russian Cruise Missiles." Air Power Australia. Accessed June 8, 2023. https://www.ausairpower.net/APA-Rus-Cruise-Missiles.html. ; Kopp, Dr C., AFAIAA, SMIEEE, and PEng. "MARITIME STRIKE - The Soviet Perspective." Air Power Australia. Accessed June 8, 2023. https://www.ausairpower.net/TE-Sov-ASuW.html.
