The unbearable lightness of heavy artillery

[YankeeDog]

I suppose it's bad form to help the guy on the other side of a debate, but here's a photo that looks, at first glance, like it might show both 5" and 40mm flak airbursts:

(Click link to see full size image -- http://www.navsource.org/archives/01/015701b.jpg)

(Taken from the USS South Dakota, showing the USS Essex under kamikaze attack, off Okinawa in 1945).

So yeah; in addition to the larger smoke puffs in the foreground and mid-background, there's a whole mess of what look like smaller smoke puffs in the distant background. I don't really know what they are. My initial instinct is they might be from 40mm rounds detonating at tracer burnout, as Jason theorizes. Or they could be more distant 5in. airbursts. Or they could just be a photo artifact. But I'm not going to buy they're deliberately fuzed 40mm airbursts until I see at least a hint of evidence that there was a 40mm time delay fuze in use by US Navy in 1945.

EDIT: Pic is huge. Changed to thumbnail w/ link for easier browsing..

[JonS]

Forget that photo. I should not have used it ... Don't obsess over Guadalcanal. That is a dead horse. My apologies for dragging it into the discussion in the first place.

But Michael, you specifically used that picture as an example of how easy it is to distinguish between 40mm and 3-in/5-in time-fuzed airburst :confused: We can't really just ignore it, because it's become an example that distinguishing between the two - in a photo - maybe isn't all that easy, and perhaps evidence for time-fuzed 40mm airburst should be sought elsewhere.

[Michael Emrys]

You still haven't rebutted the total absence of a time delay fuze for the 40mm on ordnance lists, and a complete lack of any mention of calculating or setting time delay in the training and technical manuals for the 40mm. A safety self destruct feature on tracer burn-out definitely does not count; this is not something that could have been used to create a targeted flak field.

Since I have not been able to discover documentation to the effect that there were time delay fuses, I concede the point...for now.

Michael

[JasonC]

Michael wrote - "lists maximum range as horizontal: 10,850 yds vertical: 7,625. That should work out to about a five second burn or a bit less."

The muzzle velocity was 880 meters per second, and it slows down right out of the muzzle. The maximum range you give is 11.25 seconds at that muzzle velocity, not counting the climb or the slow down. In practice, the site I quoted above gives the flight time to burn out at 8.5 to 10.5 seconds, reaching a significantly shorter range than your figures.

Gravity would only slow the shell by 50 or so m/sec in that flight time at a 30 degree elevation angle (which is quite high for such shooting, I wanted an upper bound), but the shell is certainly slowing down from air resistance. For comparison a rifle bullet drops about 10-15% in speed in just a few hundred yards / tenths of a second rather than ten seconds.

[LukeFF]

Jebus those Bettys are low! :eek:

And (as of two years ago), the pilot of the left-hand Betty is still alive:

http://www.ww2aircraft.net/forum/stories/legendary-betty-pilot-alive-30835.html#post837096

"We were ordered to drop torpedoes 1,000 meters close to the target, so we had to fly as low as 5 meters above the sea surface. Why? Warship machine guns could not shoot us if we fly below the height of their deck."

Only his Betty survived the mission.

[YankeeDog]

And (as of two years ago), the pilot of the left-hand Betty is still alive:

http://www.ww2aircraft.net/forum/stories/legendary-betty-pilot-alive-30835.html#post837096

Fun quote. Actually untrue, though -- the most common light/medium AAA on the U.S. ships at the time was the 1.1"/L75. These mounts could depress to -15 degrees, so they would have had no problem hitting a plane 6' off the water, at 1000 meters. Other U.S. light mounts, like 20mm Oerlikon and .50 BMG, could also do negative elevation.

I suppose some of the mounts might have been positioned in such a way that obstructions on the ships prevented maximum depression, but not most. See e.g., the gun tubs on the USS Enterprise, most of which were just below the level of the flght deck along the sides of the ship and most definitely did not have any obstruction preventing them from shooting downward.

More likely what flying that low did was make the planes very difficult to spot until they got close. Especially under flat lighting conditions, dark plane against dark sea is going to be difficult to spot.

[Sublime]

ha maybe thats why only one Betty survived. They mistakenly thought the guns couldn't depress

[c3k]

How high was their altitude limit to ensure their torpedoes did not porpoise or break?

[Bulletpoint]

ha maybe thats why only one Betty survived. They mistakenly thought the guns couldn't depress

I don't think they would keep thinking that for long, once their planes started to go down. Probably the real story is that what he is saying in Japanese is: By staying low, *some* of the AA-guns on the ships couldn't hit us.

[dieseltaylor]

It occurs to me that the published photos may be doctored for public consumption and that is why it is hard to make sense of it.

In the back of my mind I recall something about different tracers so guns could register their guns fire more easily - am I dreaming? : )

[Sublime]

I don't think they would keep thinking that for long, once their planes started to go down. Probably the real story is that what he is saying in Japanese is: By staying low, *some* of the AA-guns on the ships couldn't hit us.

No I dont mean after they were hit obviously. I meant perhaps the mistaken belief US guns couldnt depress enough led to the tactic of flying in at super low level.

[c3k]

Flying low had a very great benefit vs. enemy fighters. By hugging the dirt, you've eliminated the ability of the enemy to come up from underneath. That's minor. The BIG benefit is that it removes the ability of enemy fighters SWOOPING in on you. There is no "pull up" room. If the enemy dives down on you, they die. They've got to -ease- down. That gives your tail gunner a much easier shot. Defensively, staying low is very good.

As well, it reduces spotting time.

Drawbacks: inability to manuever; possibility of crashing due to minor deviation.

[YankeeDog]

Good points, C3k. Especially true of the Betty, since it lacked a ventral turret of any kind and therefore was very vulnerable to attacks from below.

While extremely low altitude attack did have certain benefits, I suspect the "fly low so the enemy's guns can't hit you" was as much propaganda intended to steel nerves as anything else. Especially the pre-1943 Bettys were absolute deathtraps, even more so on torpedo runs where they had to fly straight and level at relatively low speed during the attack. They were a large target, had virtually no armor, no self-sealing fuel tanks, and had a fairly poor defensive armament (only the tail 20mm was much of a threat to attacking fighters). US Navy gunners shot them down in droves.

They did somewhat better when attacking from high altitude, especially early in the war -- in the vast expanses of the Pacific, their long range and relatively good speed meant they could often achieve surprise, drop their bomb loads, and escape before Allied fighters could climb to meet them. These advantages diminished as the war progressed -- newer fighters had better climb rates, and increasing availability and quality of Radar meant that Allied ships and bases often had advance warning of their approach.

[dieseltaylor]

Reminds me of the great days of playing Battleline's Flat Top. Great game especially if you used three sets and umpires. Of course now Vassal exists.

http://boardgamegeek.com/boardgame/2529/flat-top

[agusto]

Flying low had a very great benefit vs. enemy fighters. By hugging the dirt, you've eliminated the ability of the enemy to come up from underneath. That's minor. The BIG benefit is that it removes the ability of enemy fighters SWOOPING in on you. There is no "pull up" room. If the enemy dives down on you, they die. They've got to -ease- down. That gives your tail gunner a much easier shot. Defensively, staying low is very good.

As well, it reduces spotting time.

Drawbacks: inability to manuever; possibility of crashing due to minor deviation.

Haha, that post reminded me of the great times i had when i was playing IL-2 Shturmovik (that is a ww2 air cobat sim, for those of who you havent heard of it yet) back in the good old days when i still had a joystick.

Another advantage of flying very low is that you are much harder to spot and that you can use terrain elevations for cover & concealment. If your are attacking a ship on the ocean, you can also "bounce" your bombs of the surface of the ocean if you drop them carefully, so they hit the ship from the side. That works very much like a flat stone that is throwen on the water in a flat angle.

[dieseltaylor]

Skip-bombing

http://forum.armyairforces.com/Skip-bombing-effective-m208253.aspx

[JasonC]

"They did somewhat better when attacking from high altitude, especially early in the war "

Um, land based air mostly in the form of Bettys and Nells (their shorter range cousins), mostly dropping the excellent Japanese torpedos not bombs, and from wavetop height not altitude, ruled the seas in the early war. That is what sank the Repulse and Prince of Wales off the coast of Malaysia in the first days of the war. That is what isolated the Philippines, drove the Royal Navy clear back to Columbo, made the Mandate islands a Japanese lake, etc.

Yes those twin engine bombers were quite vulnerable to fighter aircraft. But first there had to be fighter aircraft anywhere in the five boroughs, then they had to find and intercept the things, which wasn't trivial with the low speed edge the interwar year types had. They were flying gas tanks with stupendous range; the same lack of protection that made them easy to "flame" made them light and gave them the ability to cross huge expanses of the Pacific, where early war Allied fighters could barely get beyond eyeshot of their take off strip before they had to turn around.

They declined in effectiveness only when they faced (1) long-legged P-38 Lightnings with external tanks, or (2) improved carrier fighter aircraft, in numbers and in speed, like the Hellcat, and above all in coverage as the US carrier force grew in numbers - but that happened quite late in the war.

In the late war they were also vulnerable to the vastly improved AA on US warships, but early war shipborn AA was pathetic and never stopped them from taking out even the largest capital ships.

[c3k]

Had lunch at a shop outside an airbase. I shared a table with an old guy. He'd flown B-25's over Germany. He talked about un-assing out at low level, for the reasons I listed. Plus, it let the gunners unload .50 cal on everything they could see.

I asked about tough situations. He stated that he did lose an engine once after leaving the bombing target. No, not from a fighter. He hit a cow.

Low level works to increase survivability. (WWI, altitude worked: you'd be past the interceptors before they could climb to meet you.)

[Sublime]

The US experience would seem to have been a lot different. In the Pacific against ships at least... Using Midway as example the Torpedo squadron was butchered, to little effect, while it was the dive bombers who sank the Japanese carriers.

Oh and also on flying low - it gives you no time to react if you're hit. You're dead as soon as something goes wrong, or the pilot picks his nose.

edit: C3K the gunners comment is interesting. The constant strafing of anything and everything seems to have been a huge boon to the Allied cause (obviously). The absolute chaos and strain on movement in daylight was a great side benefit to having fighters escort the bombers all the way to and from targets. All those P51s and P47s haunting the air over Europe. I always wondered how often civilians were killed from ordnance that missed, failed to detonate, etc. Also wouldnt the streams of 50 cal casings and 20mm casings and whatnot damage things 5 miles below them?

[YankeeDog]

The US experience would seem to have been a lot different. In the Pacific against ships at least... Using Midway as example the Torpedo squadron was butchered, to little effect, while it was the dive bombers who sank the Japanese carriers.

Midway is not a good example of the effectiveness of U.S. Torpedo bombers in the Pacific over the course of the war as a whole. The U.S. TBDs at Midway were obsolete TBD Devastators, which were extremely slow and fragile. The Zeroes simply owned them. They also came in alone, completely without fighter cover. Further, they were carrying the faulty Mk 13 torpedo. While Mk. 13 wasn't as bad as the downright infamous Mk 14/15 designs (which were larger torpedoes, intended for ship/submarine launch), the early war Mk 13 had some serious problems with breaching and failing to run straight.

Midway was the last battle the the Devastator fought in; it was replaced immediately thereafter by the substantially more competent TBD Avenger; a few of the first Avengers off of the assembly line actually participated in Midway, taking off from Midway island rather than the carriers. It took longer to sort the torpedo problems, but U.S. torpedoes were effective enough during the latter half of the war. See, for example, the sinking of the battleships Musashi and Yamato, where TBD Avengers scored a number of very important hits with torpedoes.

But I think it is fair to say that the Japanese had better success with torpedoes in general (regardless of launch platform), especially in the early war. I think this was pretty much entirely due to their superior torpedo designs, which were technologically far better than anything the U.S. had up through 1943, and arguably still marginally superior after that.

[Michael Emrys]

Reminds me of the great days of playing Battleline's Flat Top. Great game especially if you used three sets and umpires. Of course now Vassal exists.

http://boardgamegeek.com/boardgame/2529/flat-top

I second that. Flat Top is a truly great game that deserves to be on computer.

Michael

[Michael Emrys]

...TBD Avenger...

Um, you do mean TBF, don't you?

Michael

[Michael Emrys]

In the back of my mind I recall something about different tracers so guns could register their guns fire more easily - am I dreaming? : )

I have read of some navies—the IJN for one—putting colored dye in their main battery shells so that they could identify which ship a particular burst pattern came from. Could that be what you are thinking of?

Michael

[JonS]

ISTR different nationalities used different coloured tracer.

[Michael Emrys]

ISTR different nationalities used different coloured tracer.

I've heard that this was so for army use for e.g. MGs. It does not strain the imagination to think that navies might have done the same. Whether that was deliberate to distinguish own fires from other nationalities', or was just coincidental, I have no idea.

Michael