The Ship Model Forum

Thanks John. Seems like the only views I get of it or what Tim the Toolman had of Wilson, his neighbor.

I cobbled something together with a 1/700 SC radar and plastic rod. No one can tell me I'm wrong, since they can't see it either!

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Martin

"Tomorrow is the most important thing in life. Comes into us at midnight very clean. It's perfect when it arrives and it puts itself in our hands. It hopes we've learned something from yesterday." John Wayne

Ship Model Gallery

I've noticed same antenna in the yard photos of CV-8 -- to me the reflector aimed upwards looks identical to the "BI" antenna on the foremast platform described in the Doyle book. I recall Rick Davis mentioning something about these IFF systems being trialled on the CVs, but now that I search back for it, I can't find the post... it was somewhere either in this thread, the YORKTOWN thread, or the ENTERPRISE thread...

Attaching a view I have - the BI antenna on the foremast platform has had brightness/levels adjusted to make the detail more obvious.

Ian/etc,

I have been puzzled by the early IFF equipment utilized by the USN in early 1942. I known that the USN had "teething" problems with these systems and that the carriers had the systems by Midway, but that not all aircraft did. The technology was evolving and went through several sets of equipment in the process. Many of the early sets apparently saw limited service.

I found almost by complete accident, a series of documents (in RG 313) discussing the IFF equipment being built in early 1942 and the delivery of these systems to the fleet, on one of my last trips to NARA (September 2019).

There were several IFF equipment sets being built and as of 1 January 1942;

BE (Transmitter) ... 34 units ordered and 32 delivered
BF (Receiver)... 32 units ordered and 30 delivered
ABA (installed in aircraft) ... 104 units ordered and 77 delivered
BI ... 3 units ordered and 3 delivered

(The delivery notes didn't include to which ships they were assigned)

In addition production for additional units was being contracted in a big way with deliveries to start in May 1942, as follows;

ABA ... 10,500 units to be ordered
ABK ... 10,500 units to be ordered
BL ... 500 units to be ordered

As you can see, there were ONLY 3 "BI" IFF systems made and it isn't clear to me which ships received this system. A document dated 30 January 1942, mentions several interesting details. The BE/BF set(s) had TWO antennas; a "mattress/curtain" type (CG66AAD) and a "Yagi" type (CG66AAB). (These two types of antennas can be seen in the above photo) Another paragraph notes that "One model BE/BF equipment, complete with Yagi antenna (was delivered) to USS HORNET."

From a list of equipments in each of the IFF systems on order from 1 October 1941, it is clear that BE/BF systems (transmitter and receiver) were utilized as one system and that BE (transmitter) system could use either the Curtain (CG66AAD) or Yagi (CG66AAB) type antennas, while the BF (receiver) system used the Yagi (CG66AAB) antenna. The BI system used the CG66AAM antenna. I still have no idea of what this antenna looks like

I believe that Tracy White had found a report of the IFF installation on USS HORNET in her Departure Report at Norfolk Navy Yard and that when USS HORNET went to the Pacific, she carried new IFF sets for the other carriers.

As a reference of the early IFF systems, here is a listing in a document from 1945 listing the various IFF equipments used (or had been used) by the USN ...



I have a document of USN antennas created in the early 1960's, these antennas are listed, but no particulars like size or description are given nor are images shown.

Thanks Ian. That's the clearest look I've seen of that area.

Rick - thanks for the info. The location of the smaller antenna is a head scratcher, as it would only be able to transmit in receive in a limited arc. At this point, no one can tell me what I've fabricated is right or wrong!

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Martin

"Tomorrow is the most important thing in life. Comes into us at midnight very clean. It's perfect when it arrives and it puts itself in our hands. It hopes we've learned something from yesterday." John Wayne

Ship Model Gallery

Martin, I can't answer your question directly, but somewhere in the back of my mind I thought they had two of these Yagi antennas, which as you can see are hard to see. The problems with line of sight and correlating these separate antennas from the search radars, was why the USN went with colocating the search and fire control antennas with the IFF antenna. In the early periods with the FD radar and SC/SC-1 search radars on destroyers (and other ships), the IFF function was handled via the BL "stovepipe" antenna which was omnidirectional and less than precise on which aircraft was a friend and not.

I don't know what Tracy found on Hornet, but he found the departure report for Yorktown which documented installation of her BI set. The early sets were experimental, and so were installed wherever they could fit without structural changes. Those structural changes would only be made for permanent installation of "proven" hardware.

Dick, I stand corrected about the Departure Report was for USS YORKTOWN, not USS HORNET. It has been awhile since we discussed the IFF system installs on the early carriers. I couldn't remember where this subject was discussed and relied on my failing memory.

True that the early IFF sets were experimental, but they were an operational system in any case. The early SC and FD radars were really still experimental as well. The first of the SC and FD radar systems installed on a destroyer was in September 1941, by NRL and contractor engineers at the Washington Navy Yard. I'm still amazed that the first "production (in fact still experimental)" radars were installed in December 1941 onboard the destroyer USS ROE (DD-418) and that the improved and more powerful SC-1 radar was available in about March-April 1942 for installation aboard ships. The reliability of these early systems was really very poor. Also, as more "electronic" microwave emitters (radar, IFF, comm) were added aboard USN ships, the USN had to learn how to adequately place these systems onboard ships for the best performance and non interference.

I improvised. No one can tell me I'm wrong (of course, now a picture will show up)

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Martin

"Tomorrow is the most important thing in life. Comes into us at midnight very clean. It's perfect when it arrives and it puts itself in our hands. It hopes we've learned something from yesterday." John Wayne

Ship Model Gallery

Martin,

You don't have to change anything if you don't want to. As you say, not many people will know the difference. But, the antenna you have made before the Mk 37 director isn't a Yagi type antenna. Look at the image that Ian posted and it is clear that the antenna before the Mk 37 director is a Yagi type. The antenna in the foremast, is a mattress/curtain type antenna. Without getting into antenna theory, "Mattress/Curtain" type antennas, like SC, CXAM, etc can be called "vertical arrays" that use multiple dipoles to get more power gain with a reflector screen. Yagi antennas, use "horizontal arrays" stacked in series and maybe also in parallel to get more gain. Yagi antennas were seen on a lot of USN aircraft during WWII. They were more compact and feasible on an aircraft platform. A common type of Yagi antennas seen today are for use as TV and radio antennas.

How then Yagi antennas have many different designs. Below are some types and callouts as to what various parts of them are for.







Like everyone else, I can't tell from the Ian image what the whole antenna looks like, but it looks like it is a wide Yagi with maybe two or three parallel arrays. What the separate dipole at the top is for, I don't know. For reference, I have copied Ian's image and reposted it here.



You could for all practical purposes, rotate your antenna down 90-degrees and approximate the antenna as it appears in the image. Of course many will say "Hey Martin, your antenna fell over!"

Rick, if he has been drinking then of course it fell over.

That is a distinct possibility.

Thanks Rick. In some of the photos of Hornet, it does look like that antenna is in the position I put it in. At this point, I'm going to leave it and dare someone to prove me wrong!

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Martin

"Tomorrow is the most important thing in life. Comes into us at midnight very clean. It's perfect when it arrives and it puts itself in our hands. It hopes we've learned something from yesterday." John Wayne

Ship Model Gallery

Here's another view of the reflector forward of the Mark 37 director:



Again, to my eyes this reflector looks identical to the one mounted on the foremast. My guess for this antenna is that it was elevated to aim straight up to clear space for work on that deck, but as always that's a guess.

Martin - your model is looking fantastic!

Thanks Ian - for the photo and for the comments. Much appreciated. I agree, I think it's turn up for the moment.

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Martin

"Tomorrow is the most important thing in life. Comes into us at midnight very clean. It's perfect when it arrives and it puts itself in our hands. It hopes we've learned something from yesterday." John Wayne

Ship Model Gallery

"LIFE" captured some shots of Hornet at Norfolk in August '41. The second picture made it into the September LIFE Magazine. https://books.google.com/books?id=l0wEA ... &q&f=false
This was before she was handed over to the Navy by the builders and before she was painted into MS-12. She is wearing a solid dark color on her hull. Just curious if she was wearing 5-D during this time and during her "builder's trials"? 5-S was just authorized as a color to replace 5-D at the end of July but it was not available quite yet. http://www.researcheratlarge.com/Ships/ ... tCamo.html

AFAIK, Atlantic Fleet carriers were experimenting with Measure 4 (Black System) during this time although photos are pretty rare. Sometime around August/September they changed to Measure 12. I think it's unlikely Hornet went on builder's trials with Measure 4 if it is indeed that scheme.

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USS WASP CV-7 VIDEO SERIES

Episode 03: Construction Part 2
Episode 04: Launch
Episode 05: Builder's Trials
Episode 06: Meet the Captain
Episode 07: Commission

Wasn't the primer a dark green?

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Martin

"Tomorrow is the most important thing in life. Comes into us at midnight very clean. It's perfect when it arrives and it puts itself in our hands. It hopes we've learned something from yesterday." John Wayne

Ship Model Gallery

Martin -
As far as primer paint color is concerned, I know I had a discussion with Tracy some time back. He found records from the Norfolk Navy Yard (in Portsmouth!) that showed it was Zinc Chromate, but he could not identify if it was ZC Green or Yellow. It is kind of a dusky shade in the under construction pictures like the ones posted just above. But the side shots of HORNET at sea for the Raid show a light color where the 5 N was scuffed away - lighter than eith 5 N or 5 O anyway.
On page 30 of this CASF I raised the issue and showed some color pictures of BUCHANAN in Ms 12 that showed a real light - almost white - under color on the transom, as well as some yellow spots where paint was flaking off. I speculated that the ZC Yellow might have been bleached white by sea water (chlorine in water) but just guessing. It's possible the discussion ended up in the paint and camo section because I couldn't find it in this CASF just now. And of course I guess the ZC could have been overcoated in a light grey. We'd have to find shipyard painting records for that time. Still, look at Wiper's BUCHANAN book if you have it. There are even what appear to be red lead touchup splotches on the hull too. A number of colors that surprised me when I took up the magnifier and looked at the color photos. Didn't see any ZC Green on that particular ship.
John

Added later: I found the discussion on primer paint on HORNET's hull to which I refer above para one. In the "Camo and Coatings" folder below there is a thread I started on April 4, 2013 titled "USN early 1940s primer paints" that goes into more detail without a definitive conclusion. There are pictures in Wiper's "YORKTOWN CLASS" book that show HORNET fitting out next to the pier and seemingly in the same dusky dark or medium gray color (B&W photo, though) as above pictures. That might make me lean toward a Chromate Green color. Maybe. But my words of caution: for a number of years I drove across the James River Bridge to work most mornings and there was usually one or more NIMITZ or FORD class carriers tied up parallel to the shore at NNSB&DD (Ingalls now) nearly perpendicular to my line of sight as I was approaching the Newport News shore. In other words, the whole length of the ship was visible. Depending on the clouds, sun angle, and mist at that time on that day, the actual haze grey on the ship appeared to be 5 N, or 5 O, or 5 H, or 5 L. And I do mean the purple-blue 5N. Same ship, different day and different color. The "dusky" color in B&W could have been from the sun angle and/or cloud cover. And those photos in Wiper's book were taken long before any camo was applied, so it wasn't 5 S.
Anyway, FWIW . . .
John

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Some people make you happy, then they leave.
Others make you happy when they leave. (apologies to Oscar Wilde if he ever said anything similar, of which there is some doubt . . .)

This pic is one of her best!

https://catalog.archives.gov/id/178141224

Yet another one of the transparencies I scanned at NARA and gave to the NARA staff.

Someone is working at College Park or took a hard-drive home with them.

Date appears to be about July 1942.

Color footage of Hornet.
https://www.gettyimages.com/videos/mr_0 ... st#license

https://www.gettyimages.com/videos/mr_0 ... st#license