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发表于 2011-4-10 21:52:33
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http://www.ww2f.com/naval-warfar ... ow-did-they-do.html
My father was a carrier pilot in WW II, serving from 1941 until 1946 in the Pacific. He flew SBD's in 1942, was a flight instructor in the States for most of 1943, and returned to the Pacific flying F6F's from 1944 to 1946.
Over-water navigation was always one of the most difficult challenges that Navy pilots faced. Combined with weather which might change rapidly, navigational errors probably killed as many naval pilots as did the enemy. When flying from carriers, pilots were briefed on what courses to fly both outbound and inbound, and were advised of a " oint Option", which was the location the carrier expected to be at the time the pilots returned from their mission.
Things sometimes happened to cause the carrier to alter it's plans and in that case it wouldn't be at "oint Option". In that case, the pilot had two options; conduct a search for the carrier with what fuel it had remaining, or hope to pick up the homing beacon each carrier operated.
All US carriers were equipped at the start of the war with a device called the YE-ZB. This was a UHF (line of sight) transmitter which transmitted a Morse code letter denoting 15 degrees of a circle. If the pilot picked up a Morse "M" for instance and homed on it, then started picking up another letter, he would know he was moving an a tangential course in relation to the carrier; he would then turn and home on the strongest signal. Since this was a UHF device it worked better at higher altitudes. It wasn't extremely reliable and some pilots were better at using it than others, so pilots had differing levels of confidence in it.
Planes with multiple crew members, like SBD's and TBM's had an advantage in that the pilot could concemtrate on flying while a crew member was delegated to attend to navigation. Fighter pilots, of course, were most likely to become a victim of faulty navigation because they were by themselves, and air combat with enemy fighters would often cause them to become disoriented as to their location. My father once said he felt that perhaps as many as a quarter of all losses of carrier aircraft were due to the pilot becoming lost, but this, I think, was just a guess. In some exceptional cases, like Mitscher's command at the Battle of Philippine Sea, carriers might display lights at night to help lost pilots. In fact, Mitscher's task Groups not only displayed lights, they directed search lights straight upward, fired star shells, and turned on all deck lights on all ships, escorts included. This confused at least some of the returning pilots, at least one of whom made a landing approach on a destroyer.
Two ways, the old way and the new way.
The old way: USN carrier pilots were generally pretty skilled at navigation. One took into account the mission parameters - - - go so far at such and so speed and on such and so bearing, do whatever you supposed to do, then go back on this or that bearing to find the ship. Each pilot had a plotting board for keeping track of where he was based on the mission parameters. Before taking off, with some notable historical exceptions, he would be given the location of "oint Option" - the location of where the ship expected to be at the end of the time allotted for the mission. So starting from a known point, time, bearing, and distance navigation to another point, do your business, and time, bearing, and distance to a pre-plotted point.
The new way, as DA noted, was utilization of the YE-ZB homing system, developed by Frank Akers, which all USN carriers had at the start of the war. Without going into the boring details, this system used a morse code transmission of a particular letter for a particular bearing, a different letter for each 15 degree sector. This was a UHF line-of-sight system, so the higher you were the better. If the letter you were receiving changed, then you knew you were moving tangentially to the transmission point. You simply found the strongest signal and followed it back to the ship. In the early days of the war it was a fairly new system and some pilots were more proficient with it than others and those less proficient tended to be less believing. For example on the 4 May 42 Yorktown strike on Tulagi, there were 4 F4Fs very hurriedly sent off to deal with some F1Ms that were bothering the SBD and TBD strike planes. After performing their mission, shooting down 3 of the F1Ms, and shooting up a destroyer they happened upon, they started to head back to the ship. The division leader signaled for an increase in altitude to pick up the YE-ZB signal, but his section leader did not see the signal (although the section leader's wingman did). So the division leader and his wingman pulled up through the cloud layer, picked up the signal, and, after milling about a bit waiting for the other two, proceeded back to the ship. The section leader left behind had a problem, his radio did not work. His wingman's did. Eventually they came up through the clouds and the wingman picked up the YE-ZB signal. He also made radio contact with the ship and started flying a box pattern so the ship could get a good radio fix so to tell him which letter he should be listening for. Well, as far as the section leader was concerned, his wingman was flying in all sorts of odd directions for no apparent reason and finally signaled him to knock it off and then led the way back to Guadalcanal where they bellied in on Cape Henslow - - - with the wingman keeping a running commentary with the ship the whole time. Result was two of the ship's 18 F4Fs were lost for no apparent reason. The two pilots were rescued the next day through some extraordinary efforts by the crew of USS Hammann. Apropos of nothing else, I have the original flight instructions for this mission carried by the division leader. It clearly indicates the ship's location relative to Tulagi and the Point Option for the return. The division leader was clear in his recounting that the instructions would have gotten him back to the ship, but the YE-ZB was easier.
Even worse happened at Midway when the VF-8 strike escort improperly used their YE-ZB and all 10 of them ended up ditched at various locations. Fortunately for some of them some rather diligent PBY crews managed to find and rescue 8 as I recall. This was a combination screw up in that the flight was not given a Point Option and their own unfamiliarity with the YE-ZB system sealed their fate. They actually saw the smoke of the US task group off to their north as they headed off into the expanse of the Pacific, but were so screwed up in their navigation that the leader presumed he was looking at the Japanese.
Rich
Last edited by R Leonard; April 19th, 2009 at 09:24 PM.
As far as I know, the Japanese carriers had no electronic homing beacons or other navigational aids, and Japanese carrier pilots, at least early in the war, relied solely on good old fashioned "dead reckoning" navigation. I believe Japanese carrier aircraft with multiple crew members often carried radios which could take crude bearings on radio transmissions and may have used these whenever possible as rough navigation markers. But of course, Japanese carriers, just like American carriers usually tried to avoid frequent radio transmissions. At the start of the war, Japanese aircrew were trained in celestial navigation and thus sometimes had the opportunity to use this method to fix their position, particularly in the longer-ranged planes.
Japanese carrier pilots, flying fighters, frequently didn't even have radios in their aircraft because of weight and reliability issues, and therefore had to rely on nothing but compass and dead reckoning for navigation. They suffered the same problems as their American counterparts because of this, except that their planes were longer-ranged and that exacerbated their problems.
After 1942, Japanese carrier pilots seldom had the opportunity to operate from carriers in combat situations, more often flying from island bases, and their navigational problems may have been eased somewhat. But this was probably offset by the fact that newer pilots had less training and experience in over-water navigation and their losses due to becoming lost must have been severe.
Well, it's a debatable matter.
Mitscher was gambling that the Japanese would not be able to inflict significant damage on his ships, even if they found them. He knew that there were only two agencies that might be able to harm his forces; subs and air attack. Mitscher's fliers had just inflicted a severe defeat on the Japanese carriers, rendering their air groups practically defunct. Mitscher did not know the exact details but he knew that the Japanese carriers had been badly damaged and the bulk of their planes shot down, so it was reasonable for him to assume that air attacks were highly unlikely.
The other threat, subs, was also unlikely to be able to inflict unacceptable damage on Mitscher's ships. Mitscher knew that American ASW against Japanese subs had been very effective in the past several months, and that the last American CV sunk by a Japanese sub had been in 1942. So he probably felt that the risk of sub attack against his fast moving carriers was minimal. Mitscher could logically argue in that time and place that the odds of the Japanese being able to attack his forces were relatively low and that the benefits of recovering a significant number of his fliers who otherwise would have been lost, outweighed the risk of damage to his ships.
Whether or not one agrees with that assessment depends on the weight given to the various factors involved. My father happens to have been there, although he did not peronally benefit from the decision, and always agreed with Mitscher's reasoning.
It would be difficult for an adversary to use the YE-ZB system to locate the point of broadcast. The system was line of sight only so you had to be higher than the typical reconnaissance missions in search of enemy ships. Even if one did pick it up (requiring some pretty fancy scanning equipment to lock into that one descrete frequency) all one would hear would be a repetition of a single letter that change to another letter as you flew into the next broadcast sector. That would not tell you a thing about which way to go. Short answer, no, the Japanese did not back track on the YE-ZB to find US carriers.
On the other hand, the Japanese turned on all the lights to recover their errant strike on the the night of 7 May 1942, long before Mitscher was credited with doing so off the Marianas. There were a couple of other instances, on both sides, prior to that as well. In the US Naval Aviation circles in which I grew up, Arleigh Burke, Mitscher's chief of staff and Gus Widhlem, his ops officer was most often credited with making that happen. The thinking was that there were probably no Japanese submarines in the area anyway.
Rich
Last edited by R Leonard; June 9th, 2009 at 12:25 AM. Reason: crappy finger work on keys
My father was a carrier pilot in WW II, serving from 1941 until 1946 in the Pacific.
我的父亲是二战航母飞行员，从1941年在太平洋地区，一直到1946年。 |
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