Unknown 8th AF VHF(?) Antenna Mid-1942 - Mid-1943

[Old MacDonald]

8th AF B-24Ds carried a blade antenna on their spines that does not appear on 9th AF B-24Ds during the same period (mid-'42 to mid-'43). It looks like it was probably for some sort of VHF system, perhaps British since a similar antenna appears on some Lancasters and Halifaxes, but I've not been able to identify which.

I know the B-24Ds did not leave the factory with this antenna, although it might have been fitted at depots on ships heading to the UK, or once arrived in England. 8th AF B-17Fs seem to have been fitted with this same antenna. Note there are no wires strung from the antenna tip to the fin, so it appears the blade was the antenna rather than simply a support post.

Can you identify the radio set and antenna nomenclature and use?

TMIA

O'M

 

[billrunnels]

8th AF B-24Ds carried a blade antenna on their spines that does not appear on 9th AF B-24Ds during the same period (mid-'42 to mid-'43). It looks like it was probably for some sort of VHF system, perhaps British since a similar antenna appears on some Lancasters and Halifaxes, but I've not been able to identify which.

View attachment 509925

I know the B-24Ds did not leave the factory with this antenna, although it might have been fitted at depots on ships heading to the UK, or once arrived in England. 8th AF B-17Fs seem to have been fitted with this same antenna. Note there are no wires strung from the antenna tip to the fin, so it appears the blade was the antenna rather than simply a support post.

Can you identify the radio set and antenna nomenclature and use?

TMIA

O'M

It is the Radio Compass Antenna on the B-17 ( SRC-269-G ) - The antenna on the left in the photo. The item on the right is the support staff for the Command Transmitter, Receiver and Antenna relay wire connected to the tail fin. ( SRC-274-N )

 

[Old MacDonald]

Thanks for taking time to respond.

For the B-24D, the equivalent device to what you suggest was the SCR-269-C, which was simply an earlier variant of the "G." However, both the B-24D radio tech order and what I've been able to find online show that the two antennas for the SCR-269 (regardless of variant) were the LP-21-A Rotatable Loop (or later upgrade) receiving antenna, commonly called the ADF football, and one of several possible single-wire "vertical whip type" "sense" antennas.

None of the references I've found include a blade antenna of the type under consideration, so I'm confused.

In addition, at least for 8th AF B-24Ds, the "ADF football" and whip antennas were both visibly present along with the unknown blade antenna, which suggests the blade was for some other system. As noted in my original post, the "football" and whip antennas can be seen on 9th AF B-24Ds of this period, but not the blade antenna, which suggests the blade was for a system used only in the UK.

Radio Compass SCR-269/F /G Military Fairchild Recording
File:SCR-269 Data.png - RadioNerds
SCR-269-G Radio Compass
Radio compass reciever
Etc.

Could you please clarify? Thanks much.

 

[MIflyer]

RAF aircraft had a tall antenna mast in about that same location for the Jostle transmitter used to jam German HF and low VHF radio transmissions used by fighter aircraft.

 

[arc5stinson]

8th AF B-24Ds carried a blade antenna on their spines that does not appear on 9th AF B-24Ds during the same period (mid-'42 to mid-'43). It looks like it was probably for some sort of VHF system, perhaps British since a similar antenna appears on some Lancasters and Halifaxes, but I've not been able to identify which.

I believe the gentleman is asking about the "blade" antenna, not the ADF "football."
The "blade" is the standard AN-104 antenna for SCR-522 VHF Command Radio, 100-155 MHz. The angle of the blade on the trailing edge is the "tell."
Note that this could also be an earlier version, AN-74. Same antenna with a different mount.
The SCR-522 was installed in most US Army Air Corps heavy aircraft and fighters in the European theater by 1944.
There is an AN-104 in the Smithsonian collection:
Antenna Mast, Communications Radio, AN-104-A, SCR-522
Also a good overview at Mike Hanz's site:
SCR-522
I have a nice working SCR-522 in my collection.
Regards,
David Stinson

 

[billrunnels]

I believe the gentleman is asking about the "blade" antenna, not the ADF "football."
The "blade" is the standard AN-104 antenna for SCR-522 VHF Command Radio, 100-155 MHz. The angle of the blade on the trailing edge is the "tell."
Note that this could also be an earlier version, AN-74. Same antenna with a different mount.
The SCR-522 was installed in most US Army Air Corps heavy aircraft and fighters in the European theater by 1944.
There is an AN-104 in the Smithsonian collection:
Antenna Mast, Communications Radio, AN-104-A, SCR-522
Also a good overview at Mike Hanz's site:
SCR-522
I have a nice working SCR-522 in my collection.
Regards,
David Stinson

Thank you for the clarification.

 

[Old MacDonald]

The "blade" is the standard AN-104 antenna for SCR-522 VHF Command Radio, 100-155 MHz. The angle of the blade on the trailing edge is the "tell."
Note that this could also be an earlier version, AN-74. Same antenna with a different mount.
The SCR-522 was installed in most US Army Air Corps heavy aircraft and fighters in the European theater by 1944.
Regards,
David Stinson

 

[Old MacDonald]

Hi David

Sorry about the very long delay in responding; we've had a serious problem with an uncle for whom I'm legally and financially responsible and I've been out of pocket for more than a month. Just now able to get back into the fun stuff.

Your explanation makes sense. I'm a bit concerned that NASM's AN-104-A seems a bit shorter than the one in the B-24D photo above. However, I found the attached B-17F radio communications diagram, which comes, I believe, from an unknown USAAF communications document. The mast antenna shown in this diagram is the AN-74, which you also reference, and since the B-17F and B-24D were used operationally by 8th AF at the same time, it makes sense the B-24D antenna could well be the AN-74.

The Mike Hanz reference is also quite helpful. Do you have any information that could shed light on why 8th AF B-24Ds/B-17Fs had the SCR-522 during the summer of 1943 while the 9th AF in the North African desert did not?

 

[whstlngdeath]

In this exploded view of a B-24J, it shows that aerial. Unfortunately, it only describes it as "dorsal aerial'. It does lead me to believe that it was included in Consolidated-built ships.

 

[whstlngdeath]

Here's a shot of a B-24H that was shot down over Germany. It seems to have the same antenna, only it's not on the centerline of the fuse. Notice the various types of aerials and antenna on this particular B-24.

 

[Old MacDonald]

In this exploded view of a B-24J, it shows that aerial. Unfortunately, it only describes it as "dorsal aerial'. It does lead me to believe that it was included in Consolidated-built ships.View attachment 519227

I've made considerable progress since originally posting this request. You're correct, by late B-24D production the VHF radio system, with the attendant external blade antenna. The short-range VHF system was intended primarily for air-to-air communication with escort fighters, although of course it could be used with any station that had the necessary equipment as long as it was in line-of-sight and signal strength adequate. More info after post below.

 

[Old MacDonald]

Here's a shot of a B-24H that was shot down over Germany. It seems to have the same antenna, only it's not on the centerline of the fuse. Notice the various types of aerials and antenna on this particular B-24.
View attachment 519228

Good eye!! As noted in my response just above, the B-24's VHF systems was primarily intended for air-to-air comms with escort fighters. Your pic above show what cannot be seen in "profile" photos--that this antenna was not mounted on the fuselage centerline. This is not an abberation; photos of early 8th AF B-24Ds taken from above also show the asymmetric mounting, always on the starboard side of the centerline. See the short AN-94-A whip antenna for the SCR-535 IFF set mounted forward of the long radio beacon whip antenna--note it's also offset slightly to the right of the fuselage centerline!

The VHF blade antenna was of the AN-104 type on earlier B-24Ds. It can be identified by it's thin "cranked toothpick" shape, relatively long length, and "pointy" tip. Later, and on the B-24D and later production lines, the AN-74 antenna was used. It was much wider and slightly shorter than the AN-104, and if the photo is clear enough, can be identified by it's broader tip with small protrusion on the aft side. My B-17F diagram posted above shows the AN-74, which allowed a "clothesline" antenna for the command radio to be attached on both sides as shown in the B-17F diagram. The older AN-104 did not offer attachment locations for other antennas.

While the AN-74 was more efficient, they both served the same purpose and were technically interchangeable in the B-24's VHF system. Both antennas were used in more electronic systems than just the VHF radio systems, but that's outside the scope of this discussion.

 

[whstlngdeath]

Here's another interesting pic of a downed B-24 where I've highlighted some "upgrades?" to the aerial arrangement. The AS-27A antenna used with the ARN-5 radio navigation system combined both localizer and glideslope functions. Later B-17s carried this as well on the upper nose forward of the cockpit. More info on it here: Antenna AS-27A/ARN-5 Localizer/Glideslope (Blind Landing)

 

[Old MacDonald]

Great pic, antenna-wise!

I suspect, but do not have tech data to back this up, that the tall whip antenna was the usual marker beacon whip moved forward from aft of the top turret--although I've seen pics of late B-24Ds with two tall whip antennas, one in the usual position and one as shown in the pic above. The aft blade antenna is probably an AN-74, which had mounting holes for stringing the "clothesline" antenna wires as shown here. It's also identifiable by its width, visibly greater than the AN-104.

I may have tech data for the front post antenna, but can't put my hands on it at the moment. It may have been a later model antenna for the SCR-535 IFF system that replaced the earlier short whip, but that needs to be confirmed. By this time in the war aviation electronics were far more sophisticated than they'd been in the 1941-43 era, so a profusion of antennae was common.

The other thing this pic well illustrates is the liaison and command antennas strung from the mid fuselage top to the tips of the fins. These wires were easily detached at the fins, and held taut by the front mounts inside the fuselage. This pic illustrates what happened when the internal take-up reels went slack.

 

[whstlngdeath]

Going back to your original question that started this post, whether early B-24D Libs of the 9th AF carried these antenna, this is a shot of a 9th AF B-24D that shows the antenna in question. The caption read: "B-24 Liberator #41-11766 'Chug A Lug' 345th BS, 98th BG, 9th AF, flew in 1st Aug 43 Ploesti oil refinery raid piloted by LeRoy B Morgan, returning safely to Libya." Of course there's no telling when this particular photo was taken, and when the antenna was added. But it does appear that 9th AF B-24D's did use it.

 

[Old MacDonald]

This pic was taken in the US after Chug-A-Lug (98th Bomb Group) returned for a War Bond tour, meaning this pic was taken after Feb 44 and unfortunately does not represent her configuration when she was assigned to 9th Air Force.

This means it was taken about six months after 9th AF had been disestablished in North Africa and its combat units, including the 98th Bomb Group, moved to 12th AF, and then to 15th AF in Italy. 15th AF's operations in Italy were considerably more sophisticated than had been 9th's in the austere conditions of North Africa. More planes, more units, and best of all, escort fighters! Therefore, unlike North Africa where 9th had literally no fighter escorts, VHF was a requirement in Italy--hence the VHF antenna.

 

[MIflyer]

The AN-104 antenna is made out of wood with a metal covering. The lower portion of it is made of uncovered wood so to allow it to be mounted to the airframe without shorting out the antenna. That antenna in the first photo looks to be rather too long to be an AN-104 unless they did something different at the base and mounted it above the fuselage skin rather that through the skin as was done usually.

 

[Jan Peterson]

I just joined as I found this forum while searching for info on the VHF blade antenna PN: AN-104

My grandfather lived in Winnipeg Manitoba in the early '40's. He had an AN-104 mast which I kept after he passed.

Were these blade antennas made in Canada or possibly shipped to Winnipeg for installation on B-24s?

 

[MIflyer]

The AN-104 antenna was very widely used on a wide variety of USAAF aircraft, usually with the SCR-522 VHF receiver-transmitter. I don't know where they were made; probably several places. They were wood, covered with metal at the top end, and might possibly be something a Canadian company might manufacture or could have been sent to Winnipeg as a spare.

There is a AN-104 for sale on ebay and it also is labeled "Camfield Mfg Co." There is a company by that name in Michigan.

 

[Old MacDonald]

Hi Jan

As Mlflyer noted, the AN-104 was mounted on many US aircraft. I've seen it on Catalinas (and presumably Cansos, alhtough I don't have many Canso pics ). The presence or absence of this antenna was dictated by whether the theater or area where the ship was assigned normally relied on VHF communications. Again as Mlflyer pointed out, this was the standard antenna on aircraft in such areas. I agree with his judgment these units could have been manufactured anywhere and were probably produced at many different facilities.

I'm sure you know VHF is a short-range, line-of-sight comms system; during 1943 it was primarily used in combat theaters for bomber-fighter communications. American fighters appear to have had a VHF radio installed almost universally from 1942 on, and of course RAF fighters switched to VHF in early 1941 (which caused the German radio intercept units considerable problems for several months).

I originally started this thread because I saw them on 8AF B-24s and B-17s but NOT on 9AF B-24Ds. I've since discovered this was because 9th almost never flew with fighter escort, so VHF was not a priority. Once 9th moved to England and the 98th & 376th BGs were transferred to 12th AF, then to 15th AF, and moved to the Italian mainland, fighter escort became normal, VHF comms were required and the VHF radio system was installed in the B-24Ds formerly assigned to 9th. This explains why photos of the Libs in North Africa show the absence of this antenna, while the same ships in Italy have them installed. I'm not a 12th AF expert, but it appears the B-17Fs assigned to that NAF started carrying the VHF systems quite early on since they fairly regularly flew with fighter escort.