Thu Apr 30, 2009 9:26 am
Adrian is correct--that is the SCR-729 antenna array on either side of the fuselage. Those antennae are usually associated with B-29s that served in the CBI rather than on the Marianas bases, but there were probably exceptions. Is it remotely possible that this is actually a war weary training ship used as a backdrop for the photo? Many CBI returnees were assigned to the Phase Training stations.
Scott
Scott
Thu Apr 30, 2009 9:32 am
Second Air Force wrote:Adrian is correct--that is the SCR-729 antenna array on either side of the fuselage. Those antennae are usually associated with B-29s that served in the CBI rather than on the Marianas bases, but there were probably exceptions. Is it remotely possible that this is actually a war weary training ship used as a backdrop for the photo? Many CBI returnees were assigned to the Phase Training stations.
Scott
You know what Scott.., you are correct (as usual).., This was definately not taken on Guam (Walker most likely).., so this is most likely not the aircraft they took overseas.
Thanks Scott..,
So does anyone know what an ECM ship looked like.. or did they just carry an a$$ load of chaff????!!!!
Thu Apr 30, 2009 12:15 pm
Standard IFF (SCR-595 & 695) used a single quarter-wave dipole (about 14 inches long) usually mounted on the bottom of the airplane. Interrogator-responsors could trigger a response from standard IFF (and RACON) allowing these target’s positions to be displayed on the responsor’s CRT.
Earlier in the war, 58th Wing CBI B-29’s used SCR –729 to trigger BABS (Blind Approach Beacon System…. AN/CPN-7) as part of the SCS-51 ILS. With the move to the islands, this navigational need diminished and fewer Superforts were equipped with it. Most of those so equipped were typically intended for navigational or SUPER DUMBO rescue work. A triggered response from standard IFF that was squawking the emergency code was very wide, and left an unmistakable scope signature from returning ships that were likely to ditch, permitting a timely rescue.
Incidentally, the single forward antenna in the photo was the transmitting antenna, the larger array - receiving. Symmetrical mounting made the incoming triggered response directional. -Adrian
Earlier in the war, 58th Wing CBI B-29’s used SCR –729 to trigger BABS (Blind Approach Beacon System…. AN/CPN-7) as part of the SCS-51 ILS. With the move to the islands, this navigational need diminished and fewer Superforts were equipped with it. Most of those so equipped were typically intended for navigational or SUPER DUMBO rescue work. A triggered response from standard IFF that was squawking the emergency code was very wide, and left an unmistakable scope signature from returning ships that were likely to ditch, permitting a timely rescue.
Incidentally, the single forward antenna in the photo was the transmitting antenna, the larger array - receiving. Symmetrical mounting made the incoming triggered response directional. -Adrian
Last edited by omega7 on Thu Apr 30, 2009 3:46 pm, edited 2 times in total.
Thu Apr 30, 2009 2:57 pm
Good info.
Thank you very much!
Thank you very much!
Re: B-29 antennae .., ECM or weather.., which is which?
Wed Feb 04, 2015 3:37 pm
The SCR-729 was also standard avionics on the P-61 Black Widow night fighter. Nearly every photo I find in my P-61 books show combat aircraft in the S Pacific with these paired directional antennas. I've also seen them on C-47s in the CBI.
While the standard SCR-729 called for the AN-148-A antenna, the usual antennas seen on these aircraft have the added Bakelite 'wings' for improved aerodynamics. The 'wings' were apparently added in the 'B' version of the AN-148. There may have been intermediate variations as these antennas were used in numerous systems on different aircraft. The later version was the AT-2()/APN-2 used on REBECCA/EUREKA C-47s in the ETO which also had the 'wings.'
Some sources state that the SCR-729 was identical to the APN-2 REBECCA. Anything is possible but my research hasn't gotten that far yet. If anything, they used similar equipment.
Another system using these antennas was the AN/APX-8. This was a directional IFF system based around an APX-2 interrogator-responsor/transponder & an AN/APA-1 radar auxiliary. A rotary switch powered by an electric motor switched rapidly between antennas & the resulting information was displayed on a 3" CRT scope. I've found few references on the APX-8 in operations but it would have been a great help to Pacific hunter-killers, especially the P-61.
Jack
While the standard SCR-729 called for the AN-148-A antenna, the usual antennas seen on these aircraft have the added Bakelite 'wings' for improved aerodynamics. The 'wings' were apparently added in the 'B' version of the AN-148. There may have been intermediate variations as these antennas were used in numerous systems on different aircraft. The later version was the AT-2()/APN-2 used on REBECCA/EUREKA C-47s in the ETO which also had the 'wings.'
Some sources state that the SCR-729 was identical to the APN-2 REBECCA. Anything is possible but my research hasn't gotten that far yet. If anything, they used similar equipment.
Another system using these antennas was the AN/APX-8. This was a directional IFF system based around an APX-2 interrogator-responsor/transponder & an AN/APA-1 radar auxiliary. A rotary switch powered by an electric motor switched rapidly between antennas & the resulting information was displayed on a 3" CRT scope. I've found few references on the APX-8 in operations but it would have been a great help to Pacific hunter-killers, especially the P-61.
Jack