[ARC5] History and Context of the ARC-5 sets

[Michael Tauson]

Okay, this is vastly abbreviated so anyone who wants to fill in
details can jump when they want to.

The AN/ARC-5 system itself wasn't available until 1943 so missed out
on the early war years and prewar period.  However, what is
generically referred to as "ARC-5" equipment started its life as the
Type K around  1935 as a result of the Airmail (which I mistyped as
"Email" ... twice) Disaster of 1934.  The first of these used by the
services were the Navy RAT(-1) and RAV which served as elint receivers
among other things.  Immediately afterward, the Navy took delivery of
the ARA/ATA system which was originally speced out for the Army but
the Navy had significantly more money so got the radios first.  The
Army was struggling for systems to put in that 50,000 plane force and
finally had to use the Navy's system, redesignated SCR-274-N (for
Navy).

Radio navigation had an early start in the late 1920s when the US Mail
service was still handling airmail followed by the period when
commercial contracts were let.  (It was the cancellation of those
contacts that lead to the Army's carrying the mail and losing so many
airplanes and pilots.  That, however, is another story for another
time.)  While navigation charts and beacon lights were part of the
overall picture, there were also the four quadrant directional radio
beacons that had the [old familiar] A & N signals to tell the pilot
which side of the airway he was on.  The lights were close enough that
in any except the worst weather the pilots could see the next one when
he passed over one - 20 miles apart, I think.  (Over the Allegheny
Mountains there were added lights in a few places to keep the pilots
from doing bad things like bump into mountain tops.)  The radio
beacons were collocated with some of the lights to keep things simple.

A.R.C.'s Model B was the first used plus was the basis for the Army's
original SCR-A*-183 equipment.  (The Navy also used the Model B for
the initial equipment in the GF/RU series.)  The receivers weren't bad
but the transmitters were weak since they weren't intended for any
distance at all.  Also, the Army pilots simply weren’t trained well
enough to handle the type of flying required.  After eight weeks of
crashes, the Army stopped and had to bring in the same commercial
carriers to train the pilots while their airplanes were fitted with
upgraded equipment, the Model D based versions of the SCR-A*-183.  (I
think the SCR-AC-183 was the first of these.  Anyone?)  After that
hiatus, the Army picked up carrying the mail again until commercial
contracts were again being let.

It was that same mess that lead to the Type K derived systems based on
many conversations with Army (and Navy although this was primarily an
Army project) brass in learning what they wanted and building a system
to fit those needs.  It took General Hap Arnold losing his temper to
get Congress to release the funds to buy the equipment that the Navy
already had ordered.

Side note: There's a story that the N at the end of the nomenclature
was required by General Arnold as a reminder (rebuke) for the Navy
getting the equipment first.

Midway would have seen aircraft with GF/RU, ARA/ATA and GP-7(?)/RU
equipment aboard, dependent on type and build date.  (Some of the TBFs
might have had ATCs with ARB receivers but I don't know for sure when
that combination got to the fleet.)  The primary "communications
problem" that existed with HF equipment was operator input to the
coffee grinder when he couldn't hear anything.

Others will have to jump in on the use of VHF at Midway.  This will,
if past history holds, begin a small "discussion" on the usage and
merits or lack thereof of HF vs. VHF in the Navy during the war.

VHF was already being used by civilian air carriers when the US
entered the war.  The WE 233, which operated in the 140-144 MCs range,
was pressed into service by the Navy as the AN/ARC-4 until the vastly
superior AN/ARC-1 was available.  As to why England used it - ask Mike
Morrow; he's good with fielding questions like that.

Worldwide civilian VHF didn't come until well after the war with HF
communications and LF/MF navigation beacons giving way with time.
Both are still in use, though, the former for long distance airways
communications and the latter with NDBs (non directional beacons) like
the ones you hear.

Others can fill in as they wish.

Best regards,

Michael, WH7HG BL01vk76IM
http://www.nationalmssociety.org/chapters/NTH/index.aspx
http://wh7hg.blogspot.com/
http://kludges-other-blog.blogspot.com
Hiki Nô!