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Grognard49,

Uhmm, ...the book's preview URL was included within my last posting ... highlighted in red as I recall ...

That same preview was also the source of the other quotes/points within my last posting, as pointed out by my, "I also found several other quotes from the same book preview to be of interest wrt a Japanese invasion of Oahu, as follow:" notation.

Might I suggest drinking a LARGE coffee, double sugar, BEFORE you further tackle the details of that preview ...

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Wrt your comment about the best radar training times, I can't claim any first hand knowledge of radar other than the use of three different, modern era, mast mounted radar units on trans-Pacific sailing trips.

It always seemed to me that night time (no sun) radar performance was better than that achieved during the daytime. I was "ambushed", not once but twice, by a VLCC and a container vessel that I could physically see in the sunlight but that did not show up on my daytime radar screen at all. OTOH at night, I always knew that I was "not alone" long before I could sort out the navigation lights of fast approaching vessels.

I always hung a different radar reflector from every mast that my "boat" carried but the "big boys" either didn't see me, or, didn't care.

What are the facts behind pre-dawn being the worst time for radar scanning ?

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I've since gone back and found your previous thread Nov.23/07 posting on the subject, quoted below:

Grognard49		#28	[-]
Posts: 60 (23-Nov-2007 11:52:09) More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts	robdab Your reply to bennett0 regarding the timing of the radar training can be explained by the fact that it's the best time to test the performance of the system under evaluation. The changing atmospheric conditions between night and day cause such conditions as anamalous propagation, ducting, and temperature inversion that can provide a challenging environment for any radar system. These atmospheric conditions and their effects have been recognized since shortly after the inception of radio systems. That is why training during this time is important to maximize the effectiveness of the system and it's operators. The operators need to be able to recognize the occurance of these conditions and learn to compensate for them. That's why engineers and operations officers love to conduct system evaluations at this ungodly hour. It never is popular with the troops, but it is one of the best training environments for both the operators and maintainers of a radar system. And no, I don't have any sources to quote to you, just over 30 years of experience working on radar systems from vacuum tubes to phased array.

Grognard49,

Sorry that you are having trouble with the link that I posted. It just worked fine for me.

Try books.google.com and once there do a search for, "Pearl Harbor" Wohlstetter.

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jlyons97,

I've just found http://www.ibiblio.org/pha/pha/congress/part_2.html#66 which lists

In the case of the Army, the following table reflects the places and
times at which antiaircraft units were in position:

Battery ...... In position and ready to fire by:

Sixty-fourth Regiment (alerted at 8:15 a.m.)

A (searchlight) Honolulu 10:00 a.m.
B (3-inch) at Aiea 10:00 a.m.
C (3-inch) at Aliamanu 10:30 a.m.
D (3-inch) south of Aliamanu 11:00 a.m. (possibly the Punchbowl battery ?)
E (searchlight) at Ewa-Pearl Harbor (Time not known)
F (3-inch) at Pearl City 11:05 a.m.
G (3-inch) at Ahua Point 10:30 a.m.
H (3-inch) at Fort Weaver 10:00 a.m.
I (37-mm) at Aliamanu ..... unknown but before 11:45 a.m.
K (37-mm) at Hickam Field unknown but before 11:45 a.m.
L (37-mm) at Hickam Field unknown but before 11:45 a.m.
M (37-mm) at Wheeler Field 11:55 a.m.

Ninety-seventh Regiment (Alerted between 7:55 and 8:10 a.m.)

A (searchlight) Fort Kamehameha 8:34 a.m.
F (3-inch) at Fort Kamehameha 8:55 a.m.
G (3-inch) at Fort Weaver 8:30 a.m.
H (3-inch) at Fort Barette 10:20 a.m.

Ninety-eighth Regiment

A (searchlight) Schofield Barracks (Time not known.)
B (3-inch) at Schofield Barracks 9:55 a.m.
C (3-inch) at Schofield Barracks 10:30 a.m.
D (3-inch) at Puuloa Dump, south of Ewa 11:45 a.m.
F (3-inch) at Kaneohe Naval Air Station 1:15 p.m.
G (3-inch) at Kaneohe Naval Air Station 1:15 p.m.
H (3-inch) at Waipahu High School 1:30 p.m.

*Please note that list comprises only 60x3" AA guns of the 88 available on Oahu that morning. It is unknown if this list details only the positions of the Army's 60 mobile 3" guns (which I believe is the case) or, if it also lists some of the Army's 28 fixed 3" AA mixed in as well ?

*Please note that the 37mm AA ammunition had only arrived on Oahu some 2 days previous and had not yet been fully unloaded from its cargo ship when the Japanese struck. While the batteries did deploy, those gun crews had not yet had any training on the operation of these new AA pieces, let alone any time for target practise against either stationary nor against targets towed at attack air speeds. As such I feel it safe to assume that they, despite their best efforts that day, would contribute little to the US AA defenses on Dec.7'41.

glenn239,

Your posting #213 concluded for B-17s,

" ... and assuming a range without bomb load of 2,300 miles, a 2,000lbs load can be carted out to 900 miles. Until better information comes along, this is the value I'm assuming."

I've found http://books.google.com/books?id=wm2mz4weQNsC&printsec=frontcover&dq=%22The+Army+Air+Forces+in+World+War+II%22&lr=&num=50&as_brr=1&sig=gzCRaN2kA_SKL4EZ48ZoNPewPOQ#PPA197,M2 which is a full books.google.com preview.

The footnote on pages 196/197 therein provides some detail on the proper terminology used when discussing WW2 aircraft ranges. It seems that the authors feel that an average aircraft's 'tactical radius' was something between 3/8 and 2/5 of its 'combat range'. In the case of your war loaded early war B-17 then
2,300 x 3/8 = 862 miles and 2,300 x 2/5 = 920 miles
so your estimate of a 900 miles radius seems to be right "in the ballpark", so far.

However,

Page 205 indicates that the B-17B had a maximum range of 3,000 miles (on a maximum 2,500 gallon fuel load that must have included 2x400 gallon bomb bay fuel tanks, while a normal fuel load was 1,700 gallons) but that with a combat bomb load of 2,400 lbs its combat range was reduced to 1,500 miles. 3/8 to 2/5 of that gives a combat radius of only 562-600 miles but, there were no B-17Bs on Oahu on Dec.7'41.

The same page also credits the B-17C/D (which was the most numerous B-17 type at PH on Dec.7'41) with a range of 1,280 miles while carrying 2,400 lbs of bombs. 3/8 to 2/5 of that range gives a combat radius of only 480-512 miles, nowhere near your 900 mile estimated combat radius. Lets average it to 500 miles for ease of discussion, shall we ? Of course, more range could be gained by further reducing the bombload carried.

Perhaps this is the reason that the US chose to extensively mine French Frigate Shoals in the spring of 1942 rather than just periodically sending over B-17 patrols ? I'd guess that a B-17C/D/E could get there (700 miles one way) and then safely back to Oahu but it's bomb load would have been greatly reduced to make such a flight possible.

Page 206 details the European performance of later mks of the B-17 with a 600 mile radius for a 5,000 lb bombload and a 700 mile radius for a 4,000 lb bomb load.

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Wrt the outlying Hawaiian islands handling 7.6 million tons of cargo in 1939, this represents an average of 20,800 tons per day, every day. But one has to ask how many islands/ports this total is spread over ?

And was any of it moved over open beaches ?

I believe that jtjohn1 and dolphinstriker were trying to make the point that in the event of a "non-surprise" Japanese invasion of the type that you have proposed, it would be prudent for the US defenders of those outlying islands (and I acknowledge that not all were defended by the US) to place demolition charges under every dock, pier, bridge, railway track, and crane that existed there.

In this case 1939 cargo tonnages would NOT be a realistic estimate of Japanese cargoes moved, by hand, over soft sand beaches and surflines.

In a surprise attack scenario many port facilities might be captured intact but you fully intend to give the US defenders several days to prepare to fight this AH invasion by 'scorched earth' methods. And fight they would.

glenn239,

" ... your estimates for the combat radius of the B-17C and D looks too pessimistic to account for known performance at Midway in June 1942." They are not my estimates. They come from the URL source that I have presented for any and all to double check.

Any difference is probably because 7 months later the USAAF had likely upgraded to mostly B-17Es with a few of the even newer B-17Fs thrown in, rather than flying mostly B-17C/Ds with just a few B-17Es arriving on Oahu as was the case on Dec.7'41. I'll have to look at Midway bomb load weights also to see if they were extending their ranges by carry the same total number of bombs but with each bomb being of a lesser size and therefor a lighter total weight ?

For example, http://www.history.navy.mil/faqs/faq81-9.htm contains discussion of bomb bay and other fuel tanks being fitted into B-17s prior to their dispersal to Midway and goes on to present, "The burden of long-range search rested upon the PBY-5A's and the B-17's; twelve of the latter covered long arcs extending 800 miles out from Midway on 31 May and 1 June, but they sighted nothing and they could not cover the area lying beyond 300 to 400 miles northwest of their base, for here visibility was poor. Their efforts held the flight crews aloft for thirty hours in the two days prior to combat, nor could the crews rest in the intervals between flights, for it was necessary for them to service their own planes, ... " No wonder then that the US B-17s didn't hit much of anything Japanese. Notice the use of the phrase 'long range search', not the use of the word 'attack'. The same URL informs us that by May 18'42 there were some 34 B-17s on Oahu of which only 7 were the older B-17C/D models. By the end of May some 44 of the 56 avaialbe B-17s there were in commission due to reinforcement flying in from the US West Coast. In fact 60 B-17s arrived between May 18'42 and June 10'42.

The same source goes on to say on it's page 457, " ... nine B-17E's led by Lt. Col. Walter C. Sweeney, Jr., of the 431st Bombardment Squadron surprised the transport force with its supporting craft some 570 miles west of Midway, dropping 36 x 600-lb. demolition bombs from 8,000 feet." so we can surmize that the B-17E model had a comabt radius of at least 570 miles with an extra fuel tank installed in its radio compartment AND 4 x 600 = 2,400 lbs of bombs on board. That's still nowhere near 900 miles one way.

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Your Hawaiian Island cargo tonnage information is interesting BUT still tells us little today about the ability of your AH Japanese invaders to unload airfield repair materials, aircraft fuel, spares, equipment, ordnance and possibly even replacement aircraft over the soft sandy beach surflines of those outer islands.

You have not yet addressed the probability of US 'scorched earth' defensive tactics rendering the existing US cargo handling facilities unusable by your AH Japanese.

Certainly the historical Japanese proved to be masterful at seizing local civilian land and sea vehicles for their own supply transport purposes but with several days of advance warning I can imagine civilian vehicle distributor caps all over the Hawaiian Islands being buried, burned or thrown into the surrounding ocean, in great numbers just after the first Japanese landings.

Wooden piers, warehouses and bridges can simply be burned if dynamite is not available. I must admit to having no knowledge of whether such tactics were used, or not, by the US defenders at Guam or Wake however.

Nor to any knowledge wrt the speed with which IJA engineering units might re-open such damaged port facilities, roads and railway lines. I do know that the British were amazed by the speed with which IJA engineers rebuilt Malayan highway bridges after the retreating British troops had destroyed them.

Did the British think to destroy the port facilities of Hong Kong or Singapore as the Japanese overran them ?

I would be most interested to know how the Japanese supplied their airfields (captured from the British) near Koto Bharu but I have been unable to find such detailed information. The Japanese advance thru the NEI's airfields shows that they had devoted much thought to the matter. We know from history that it WAS done but other than some fuel actually be captured on those ex-British Malaya airbases, I don't yet know HOW it was done.

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Your coast watcher story is also quite fascinating. Could one count this as an act of sabotage, by omission ? Especially since I assume that the individual concerned was being paid to act as a coast watcher ?

Considering the just recently completed transfer of one of the two Hawaii raised US infantry regiments to garrison some of the outer Hawaiian Islands in battalion and company strengths, one wonders if Short also had some suspicions about the true fighting will of some of those US soldiers of recent Hawaiian and Japanese ancestry ?