The Roundtable
Forum
Official Newsletter of the Battle of Midway Roundtable
4 April 2011
Issue Number: 2011-08
Our 14th Year
~ AROUND THE TABLE ~
MEMBERS’ TOPICS IN THIS ISSUE:
1. Japanese Estimates of USN Aircraft Combat
Radius
2. World War 2 History Site
<>
<> <> <> <>
1. JAPANESE ESTIMATES OF USN AIRCRAFT
COMBAT RADIUS ( see issues #6 and 7 )
---------------------------------------------------------------------------------------
23 March 2011
From: Lu Yu
Iowa
I appreciate
the comments from Jonathan Parshall, Barrett Tillman and Scott Smith, which
helped to clear some of my confusion.
Regarding the usage of statute mile vs. nautical mile, Jon's opinion is what I
thought, that is, both navies use nautical mile as their unit. My confusion actually comes from the unit
used for aircraft's performance, e.g., range, combat
radius and speed. Sometimes I
see miles used and sometimes nautical miles.
For speed, some use MPH and others use knots. It seems to me that "mile"
can mean "statute mile" in some situations.
I agree that combat radius of aircraft is not a solid number and depends
on many factors. Even though the
Japanese might have got some intelligence on American aircraft's
performance through pre-war effort or lessons from Coral Sea, it should
not have been considered as solid data and should have been used with caution.
Given the above light, I now tend to believe that the "combat radius and
distance" issue as in Senshi Sosho is more or less an excuse for Nagumo
and his staff's tactical blunder. Had
they really been concerned about this issue, they should have noticed the
following events and facts:
(1) From 0755 to 0810, Henderson's
SBD-2s from Midway attacked Hiryu and several bombs were
dropped. The SBD is a carrier-based
plane. At that time, Nagumo had
received Tone #4's initial report, so he knew that at
least some American warships were nearby.
He should have considered the possibility that these SBDs were launched
from a carrier. [Note 1]
(2) At 0855 Tone #4 search
plane sent a message to Nagumo, "10 enemy attack planes heading for
you." Given Tone #4's
position at that time, these planes could only have been launched from a
carrier. They were actually VT-3. This message should have given Nagumo a
warning that their calculation about the "combat radius and distance"
issue was not correct.
(3) Just after Kido Butai changed
course at 0917 to 070 degrees, VT-8 began their attack. They were carrier-based torpedo planes. This is another warning for Nagumo. Then at 0940 VT-6 began their attack. Yet another warning that not only
their calculation of "combat radius and distance" was wrong
but their estimated number (one) of American carriers was probably also wrong. Nevertheless, Kido Butai kept a
north-northeast course toward American carriers reported
position, except when American torpedo plane attacks forced them to
take evasive maneuver.
(4) The Japanese carrier-based aircraft
have considerable advantage on range and combat radius over their American
counterparts. A typical mixed Japanese
"attack wave" could be launched from some 240 nm away. [Note
2] After all, longer range
was among the Japanese main goals when they designed their
aircraft. However, Nagumo failed to
take this advantage. Taking Tone #4's
reported position at face value (some 210 nm from Kido Butai), there was
still no reason to close the distance. Nagumo could have put Kido
Butai at a distance where he could launch and recover attacks and the Americans
couldn't attack him effectively. It is true that carriers at that time
often steamed toward the target after launching attack planes, in order to
reduce the returning distance for the attack planes. (Nagumo, Fletcher and Spruance all did it at Midway.) But Nagumo was nowhere near launching at
0830 or 0917 and nor was he at any time before his 3 carriers were
fatally bombed around 1025. In hindsight,
Nagumo's choice of Kido Butai's course is almost the worst he could
have done.
Note:
[1] It is possible that during the heat
of the battle, people on board Akagi failed to notice the plane type of
those SBDs and people on board Hiryu, being under direct
attack, noticed it. This is one
possible reason why Yamaguchi urged an "immediate launch" of attack
planes around 0830.
[2] The A6M2 Type 21 Zero fighter
has a much greater combat radius than 240 nm.
I have no direct data for D3A1 and B5N2. As a reference, according to Akagi's action report, her
carrier bomber unit for attack on Midway assembled and started from
31-12N 179-30E, 242 nm from Midway. Kaga's
and Soryu's report gives their carrier's position at 0445 as 31-26N
179-40W (this position is inconsistent with Kido Butai's course track in Nagumo
Report), 228 nm from Midway. Also, at Pearl Harbor the first attack wave
were launched some 230 nm north of Oahu.
---------------------------------------------------------------------------------------
24 March
2011
From: CDR Alan D. Zimm, USN-Ret
Maryland
With regards
to the discussion regarding the calculation of combat radius, the Naval War College has a collection of
documents from the period 1927-1946 that
supported the wargaming program.
If I recall correctly, BuAir calculated combat radius as follows:
§
Beginning with
full tanks 15 minutes at idle for warmup
§
15 minutes at
full military power for launch and join-up at altitude
§
Cruise to target at maximum range cruising speed,
~75% VMax (max cruise, that speed that would allow the aircraft to cover
the longest distance)
§
30 minutes full
military power over the target
§
Return to base
at max cruise
§
30 minutes orbit
over carrier awaiting landing, at max endurance speed, ~60% VMax (max endurance—that speed that would
keep the aircraft in the air for the
longest time)
§
30 minutes reserve
fuel at max endurance.
(The above figures are from memory—if
someone needs verification I'd have to
dig through my notes.) According
to a NWC Maneuver Rules data sheet dated December 1942, fuel consumption for the F4F-4 was 24 gallons per
hour at max endurance, 45 gallons per
hour at max cruise, 120 gallons per hour at full military power, for an aircraft fully fueled. Fuel capacity was 260 gallons. Endurance at max cruise was 3.4 hours, 1.2
hours at military power, 6.5 hours at max endurance.
Considering that the above calculation has
the aircraft at full military power for 45 minutes, a calculation of about 100
nm combat radius is understandable. It
is also understandable that if you cut fuel consumption as soon as possible after launch, and employ military
power sparingly over the target, and if the deck is efficient and lands the
aircraft, and cut into the reserve,
that the combat radius could be extended considerably, albeit with risk of fuel exhaustion if things did
not go right, particularly over the
target.
Another factor was formation flying—leaders
could leave their throttles set while wingmen generally had to jockey their
throttles back and forth to maintain formation, and this cut into the wingmen's
fuel efficiency. At Midway, with
the fighters forced to do S-turns over
the slower bombers to remain in company, not
only were the fighters traveling a longer distance per mile of advance,
but they also had the additional drag
from the turns, which would cut back on fuel
efficiency.
---------------------------------------------------------------------------------------
<>
<> <> <> <>
2. WORLD WAR 2 HISTORY SITE
---------------------------------------------------------------------------------------
21 February 2011
From:
Barrett Tillman
Arizona
Author, Clash of the Carriers; Whirlwind
http://www.worldwar2history.info/
I came across this site by while searching for something else (my preferred
method of finding stuff, it seems). Much or most appears to be
"WW2 101" for non-experts, but contains some useful
info for anyone. The Medal of Honor citations are organized
geographically.
Other portions include elite forces, the National WW2 Memorial, D-Day links,
Burma Road, etc. There's also a Wikitree link devoted to interviewing WW2
vets.
An extensive section on code breaking for Midway: http://www.worldwar2history.info/Midway/Doolittle.html
There's a bibliography link, apparently generated by viewers: http://www.worldwar2history.info/books/
---------------------------------------------------------------------------------------
~ NOW HEAR THIS! ~
NEWS & INFO IN THIS ISSUE:
- IJN Attack on
Syndey
- Featured Link
- Editor’s Notes
<> <> <>
<> <>
IJN ATTACK ON SYDNEY
It’s now well known that one of the principal reasons for the
failure of Admiral Yamamoto’s Midway plan was the wide separation of Japanese
forces, such that the various elements could not support each other. Here’s yet another example of “what might
have been” at Midway for the Japanese: five of their big submarines, two
equipped with midget subs, making a nuisance attack on the harbor at Sydney,
Australia just four days before the BOM.
To see an excellent animated graphic program detailing the attack, click this link (with
thanks to Barrett Tillman).
With the singular exception of I-168, the Japanese subs committed
to Midway did nothing to help their cause.
Would that have been true if five more of their best boats had been on
the scene?
<> <> <>
<> <>
FEATURED LINK
Here’s an interesting You-Tube
video clip showing a wartime newsreel report of the BOM. The announcer says that it shows actual film
from the battle, but keep your expectations low. There are some dramatic scenes of what may be the burning Mikuma,
but the rest of it is stock footage, some of it pre-BOM, as evidenced by
the rudder stripes on a cruiser floatplane.
Another giveaway is the Betty flying past U.S. ships while the narrator
speaks of our planes on their way to attack the enemy fleet.
But that’s all okay; it’s still a
good example of what was produced and shown to the public during the war.
<> <> <>
<> <>
EDITOR’S NOTES
~ A few members have
reported favorable results with the test of our new on-line search tool, and
we’re still looking for additional comments, pro or con. Please give it a try and then let us know
your results—see issue #6
for more details.
~ The Navy’s annual BOM
commemoration at the Navy Memorial in Washington, D.C. will be conducted on
Thursday, June 2nd. More details will
follow as the date gets closer.
~ The Naval Post Graduate
School at Monterey, California will hold its annual BOM event on June 4th. For more info, check
this website.
~ I’m happy to report that
Naval Institute Press has agreed to publish Elliot Carlson’s long-awaited
biography of Hypo’s Joseph Rochefort. I
had an opportunity to assist Elliot with some proofreading and editing of his
manuscript, and I can tell you that this will be a very, very good book,
one that gives the light of day to the story of Hypo and its commander like
you’ve never before imagined. Look for Joe
Rochefort’s War to come out around
next October.