I just watched Tora! Tora! Tora! and it’s unclear in the movie. Maps I’ve found online are inconsistent. One indicates that the Japanese carrier task force got no closer than about 150 miles on the morning of Dec. 7, 1941, directly north of Oahu - is that right?
The only hard figure I could find was that radar picked up the first wave aircraft at 136 nautical miles. Given rate of climb and radar at that time, and saying the carriers were actually opening the distance as the later wave launched, 150 miles could very well be right.
I thought it was 230 miles. And I found on line that it was 230 miles north of Ohau
230 miles due north of Pearl Harbor., according to the postwar Strategic Bombing Survey interrogation of the strike group leader of the first wave.
It’s worth noting that at the start of the war, admirals on both sides were obsessed with the possibility that enemy carriers could fly off a strike from outside normal range if there was a land base near the target carriers the planes could reach, a so-called “shuttle bombing” attack. It was believed that carriers approaching a land airbase too closely were in mortal danger of an attack from enemy carriers farther out to sea against which they could not retaliate.
I vaguely recall something like that being tried once or twice during the war, but it was seldom attempted and never the decisive factor. But particularly in the first part of the war, one frequently sees one or both sides miss strategic opportunities because of a fear of being shuttle-bombed which turned out, in retrospect, to be overblown. If you read widely on the war, you’ll see a surprising number of cases where this fear affected the decisions of admirals.
My feeling is that the communications and senors of the day made it just too difficult to arrange during fast-moving, fluid carrier operations. One would have to anticipate the enemy fleet’s movements and be in the right standoff position at the right time, and then brief the pilots for their new landing destination.
But, of course, it’s easy to imagine the enemy could be up to something complicated.
This was a long way of leading up to voicing my opinion that Nagumo probably wanted to keep the Japanese striking force as far from Hawaii’s airfields as he possibly could, while still launching his attacks.
OK, thanks! Wouldn’t launching that far away also give your planes a pretty short time to remain over their targets?
There were three types of planes involved in the attacks: “Kates,” “Vals,” and “Zekes” (Zeros). The Val had the shortest range at 840 odd miles. So they could get there and back and still have nearly 400 miles worth of fuel to burn while over the target. But mostly they didn’t need or want much time on target. For the most part the planes were carrying 1 or 2 bombs or a single torpedo. The Kate could carry 6 lighter bombs, but I don’t think many were loaded out that way for the attack. Most of the planes flew to Oahu made one or two passes over their target and then flew back.
The Zeke (Zero) had a much longer range. The type used at Pearl, type 21, had a range of over 1,900 miles. They were the only ones that really spent much time on target strafing with their machine guns and engaging with the few fighters the Americans got airborne. And they had range a plenty to hang out over Oahu as necessary.
Didn’t Fuchida, the leader of the raid stay throughout?
While true, this number is a bit deceptive. It’s the range unarmed and flying directly to and landing at its destination with no fuel reserves. Once armed, spending time idling on the flight deck waiting its turn to launch, loitering while all the aircraft formed up, having to loiter again waiting its turn to land back on the carrier and keeping some fuel reserve in case of unforeseen difficulties (strong headwind on the return flight, etc) the actual combat radius is much less than this, a combat radius of 332 nm for the Val is given here (warning pdf file) on page 6.
Well, part of the fleet actually got much nearer, I believe one midget sub entered the harbor and two sank outside it.
I vaguely remember that japanese carriers were not supposed to come less than 200 miles from Pearl Harbor. When the strike was launched they were farther than that, but after launching the attack the japanese admiral brought them closer. He knew that some of his planes will be critically short on fuel on their way back and having the carriers several miles closer could save planes and pilots. I think they came as close as 190 miles, but don’t quote me on this. 
Thanks, everyone. Very interesting.
For what it’s worth, wikipedia lists that some of the Kates of the second wave attacking the airfields were armed with smaller (60kg) general purpose bombs.
This was pretty fascinating.
http://www.pbs.org/wgbh/nova/military/killer-subs-pearl-harbor.html
Yup. Naval History magazine had an article a few years ago on whether one or more subs actually made it into Pearl Harbor and carried out torpedo attacks on the moored U.S. battleships. This photo got a lot of attention: http://www.history.navy.mil/photos/images/h50000/h50931.jpg
That’s a classic photo (taken by the Japanese) of the battle line moored in Pearl.
The TV program I saw focused on the three “spouts” in the water, center left. Most folks assumed that was something from AA or something, but the TV program asserts that that was made my either a torpedo or periscope.
What I don’t get is that while the spouts are kinda tall (compare those to the ships), the tallest one is closest to the battle line. If a torpedo was porpoising or skipping, the taller one should be furthest from the BB’s as it had more time to “grow”. It seems to me that whatever made those spouts was headed away from the battle line. I forget if the program addressed that.
Gah! Belay my last.
In that photo, they asserted that the wave curl to the right of the three spouts was made by a midget sub periscope. I don’t think the original photo could resolve a four foot stick in the water from that distance, but I could be wrong.
Perhaps planes are different than cars, but in a car if you’re thrashing it about, your burn rate goes through the roof. Realistically, I doubt that there’s much of a difference. Maintaining velocity doesn’t take a lot of energy, but if you’re quickly losing and then regaining speed as you fly in circles, zig-zag, or whatever, then you’re spending a lot of fuel to accelerate mass through the pea-soup of air, and then wasting all that fuel the instant you slow down again.
I’d have to imagine that this is a much larger factor than idling on the runway.
I wasn’t trying to imply that idling while waiting to launch was the major factor in why effective combat radius isn’t simply 1/2 of a planes range, just that it is one of the factors. By far the largest factor is the weight of the bombs. From here (another pdf), the declassified official info on the SBD-5 Dauntless dive bomber,