Malinta Hill

[chadhill]

Fots, you have made a fantastic discovery (thank you, too, Phantom). I am at a hotel computer, away at work, but can say this. I have read that on warships the Hudson 1.1 inch AA gun initially had a problem with mount vibration, when the gun would move and fire. I believe this was eventually solved, but don't recall how. What I think we see in your photos was a jury-rigged attempt by the Corregidor crew to fix the vibration problem.

Look closely at the 1942 Japanese photo of the overturned weapon. You can see that there are actually two "base rings". One is at the very bottom of the gun, and another one is just above it, slightly larger in diameter.

I believe what you have discovered is that the Malinta pom-pom gun had the very bottom base ring bolted to the steel ring in the concrete pad (this explains the holes seen). Then, concrete was poured over the bottom base ring as a "sandwich layer" between the bottom ring and the next ring above. This insulation, so to speak, provided a crude measure of stability against mount vibration.

This is an incredible discovery that you have made of the most unique weapon on Corregidor. To my knowledge no one has seen these mounts since 1942. You have definitely solved the puzzle of the location of the elusive pom-pom gun. I extend my highest congratulations.

[fots2]

Hi Chad,

You helped with this discovery as much as anyone. Thanks for the comments and ideas.

The offset center pole still bothers me as to how the lower ring bolt holes in the concrete pad would line up with the ring holes in the gun’s lower ring. Wouldn't the center pole and outer rings on the gun mount be rigid and manufactured to quite specific tolerances?

Since the upper concrete ring overlapped the bolt holes in the pad, I would expect to see nut/bolt indentations near the edges of the concrete ring (on the bottom of it). I seem to remember that the two pieces of concrete were flat on the bottom but I was not paying much attention to that at the time. My unposted photos seem to show no indentations but do not show the bottoms of the pieces clearly. It would be easy to check this out some day as they are not buried. I like your suggestion but how does the offset center pole fit this scenario?

I took a quick look online for information on this quad 1.1” Pom Pom gun. Here is some text that mentions the vibration you referred to.

“It was considered that the early quadruple mounts suffered from too much vibration so they were modified by adding large steel stiffening plates between the carriage and the base of the mounting. Later mounts incorporated this change and lacked the side-to-side slewing feature”

We may be looking at one of these steel stiffening plates embedded in the concrete pad.





(Photo Credit: NARA collection 19-LCM courtesy of Brent Jones of USS Astoria.org)

[JohnEakin]

That gun looks like it must use some sort of external power and perhaps also cooling water. I wonder if the center pipe could have been the power inlet rather than for mounting/centering? Perhaps the other end of that pipe comes out somewhere around the edge of the concrete slab.

[chadhill]

Fots, you have raised some good points.

It was hard for me to believe that after all the trouble it would have taken to disassemble the heavy gun, haul it to the top of Malinta Hill, and reassemble and finally mount it, that no one would have secured the weapon with twelve simple bolts. Especially considering the vibration history in the mounts. But the center pipe being off-center is quite evident in your photos, which I couldn't explain. Another thing that bothered me was the note discovered by John Gordon in the 16th Naval District War Diary which revealed that the pom-pom was shipped via lighter from Cavite to Corregidor on December 17th. The gun was not ready for combat until February 11th. Yes, a Crosely automobile motor needed to be rigged to drive the cooling pump, but seven weeks seemed a very long period for that during wartime. Corregidor lacked an effective AA gun for aircraft flying at 3000-5000 feet. The pom-pom filled that gap and was needed.

After some digging around, I came across a discussion on another forum about a possible manufacturing flaw in the base plate or base ring of one of the pom-pom guns on Cavite that was destined for the USS Houston. The blogger claimed there was documentation for this which, however, was disputed by the next blogger. The first blogger suggested that the defective gun, left behind, was the one that wound up on Malinta Hill. Here is the link. Scroll down about 30% of the thread to "a rethink on MARBLEHEAD'S two 1.1-inch quads".

www.network54.com/Forum/594514/thread/1320819381/De+Ruyter%27s+Illumination+Capabilities


This got me to scratching my noggin'. First, here is a re-post of your photo showing the off-centered pipe in the steel ring:





Next is a cropped, enlarged view of the pom-pom gun base ring from the 1942 Japanese photo:



This SWAG could be a case of me seeing pink elephants-the photo is admittedly from an angle-but can it be that the "pipe" in the middle of the base ring is slightly off-centered, too?

[fots2]

Hi John,

The gun did have water cooling of the quad barrels.

I stuck a wooden pole down inside the metal pipe and it bottomed after about six inches of loose soil and leaves. This may just be a rock or something blocking it though. We did not feel it was necessary to clear off all of the pad so I cannot say if a pipe appears somewhere at the edge of the concrete base...good idea though. Thanks. 

That quad 1.1” gun had a menacing look to it however the Navy was not impressed with its performance. During wartime it seems that it was being replaced with Oerlikon and Bofors AA guns whenever possible.

[fots2]

Hi Chad,

I cannot say with any certainty that the pipe in the Japanese photo is off-centered or not. If the gun was bolted down then it sure made a clean break during the blast. The bottom ring on the overturned gun shows a bit of damage (bottom right) but overall, not much. The steel ring in the concrete mount looks very good.

Too bad we cannot find the Navy’s equivalent of Army Technical and Field Manuals for this gun. That would help a lot.

The discussions in another forum were interesting and I had some comments but they sorted themselves out in later posts. They might be interested to know that we located the gun mount in question although it doesn’t help their discussions. For us, we located the actual gun position which in my opinion was our primary goal.

What do we want to find next?

[chadhill]

Hi fots,

I've literally spent hours searching online for a manual with no success, but will keep my eyes open. That would answer so many questions.

I've never posted on that other forum, but may drop them a line now with the news of your terrific find. Some high-profile types occasionally lurk there and maybe they could shed some more light on this fascinating subject.

I still think it's possible that the gun was dismantled and sent to Japan for evaluation. I came across that being mentioned somewhere online a couple of years ago and bookmarked it with our last computer, which later got zapped during a thunderstorm, and have been unable to locate the site again. It would have been a prize for the Japanese to capture an intact example of the USN's newest, though flawed, AA gun. I have been curious why a number of Japanese Navy officers are seen near Malinta Hill in the post-surrender newsreel.


Hi JohnEakin,

Good suggestion. I've wondered if the metal pipe was a conduit for fluid lines, or for electrical power lines. The pipe is so thin it would seem to offer little from a structural perspective.

As can be seen in fots' B&W USS Astoria photo above, the cooling pump or a hydraulic pump was on the bottom of the mount (although the Malinta Hill gun used a rigged Crosely automobile motor, probably attached off-gun, to drive a pump). Perhaps the pipe tapped into a fluid reservoir?

Also, SL #8 tunnel was nearby, as well as the old land defense magazine, which was nearly underneath the weapon. Could electrical lines have come from one of these places? Maybe even the Crosely powered a generator. Without a manual I am left to SWAG. I have been unable to confirm if the gun indeed used electrical or hydraulic power, though like you, I think it must have.

What appears to be some of the mechanical gearing for azimuth rotation and for elevation of the barrels can be seen in the photo below. Fots' photo also shows elevation gearing below the bottom barrel. One man controlled the azimuth with hand wheels, the other man controlled elevation. As a final note, the Malinta Hill gun is said to have been missing the fire control director, and was aimed purely by line-of-sight.

[chadhill]

I was under the impression that Searchlight #8 was destroyed by the 240mm shell that penetrated the air shaft on April 29th. This snapshot, looking east from the top of Malinta Hill, is from the May 1942 Japanese newsreel. On the left, it seems to show SL #8 still intact.

[oozlefinch]

Chad - Maybe they didn't move the generator from the old land defense magazine to the Sl-8 tunnel, and that was where Lt. Friedman and his men were killed by the 240 shell hit. The damage to the one entrance to the magazine might be consistent with a 240 hit. That magazine would also have been the most convenient shelter for the men manning the 1.1.

[fots2]

Heavy shelling on top of Malinta Hill would wreck havoc on exposed power cables if they were ran to the SL shelter in 1942 plus communication between the two places would be required. The available space at the rear of the SL shelter for an extra generator and fuel tank is also limited.

I would think that the most likely location of the Crosley engine/generator would be below the gun mount in the old land defense magazine. This is in very close proximity to the gun and in a protected structure. I estimated that power cabling from the gun mount running down the rear entrance and inside the magazine would have to be only 9 meters long. As oozlefinch said, this is also a great shelter for the gun crew. Well, unless a 240mm shell comes knocking at their door but you can’t plan for everything. I guess this shows us the difference between bombproof and splinterproof.

The following photo may be proof that at least one generator was housed in the old land defense magazine. In the ceiling are bolts and one remaining metal pipe bracket (for diesel exhaust I assume). A magazine for only small 75mm shells would not require such a ceiling pipe.







Chad, I also thought that Searchlight #8 was destroyed by that Japanese shell exploding down the rear air shaft. It does look like the 60-inch light can be seen at the left of the photo but I wonder if it is unserviceable scrap metal at this point. Even today the front wall of the shelter is intact so the light is just sitting there dead. I have not found any pieces of the thick glass lens at this searchlight but a few broken cylindrical carbon rods can be seen lying on the hillside down below the shelter (if they have not all been picked up by now). A few people know what they are looking at when they see them.

Oozlefinch, why do you think that the generator for SL#8 was in the land defense magazine? What is the sourse of that information? I seem to recall some text about the generator being remote from the searchlight but cannot find it at the moment. The searchlight and 75mm guns (and magazine) were there years before WWII. Wouldn’t the searchlight be self-contained and have its own power and the nearby magazine for 75mm shells be only for that purpose?

The quad 1.1” gun was manned by 1st Platoon of Battery ‘M’, 60th Coast Artillery (AA). The battery ‘M’ history was written by Lt. Col. E. L. Barr. Here is a section of it describing the destruction of the gun and the deaths associated with the exploding 240mm shell.

“Of all the bad days we were to have April 30th was to be our worst. The shelling began as usual at about eight o'clock in the morning but only a few shells came our way. The barrage was farther west, from D battery's position to Malinta Hill. We watched from our tunnel and saw the small explosions of the 105's and the 150's on D battery's positions. Malinta Hill was being worked over by 240's. The report of the guns was deafening, very similar to our 12 inch mortars at Ft. Hughes. The shells made a long lazy somewhat erratic whine then hit Malinta Hill with a great flash of fire and a cloud of dust. The report, a few second later, gave us an idea of the hell it must have been up there. About mid morning we saw that a good sized fire was raging atop the hill near where the pompom was located. We felt a keen anxiety for our men up there. but figured that they had one of the safest shell proofs that any of our positions had, in the sea coast searchlight tunnel there.

“We learned from some of our men in Malinta Tunnel that the pompom had been blasted out and that Lt. Friedline and some of our men had been burned to death in the fire that had swept through the searchlight tunnel. A 240 mm shell came down a ventilation shaft and exploded the gas tank of the 25 KV generator and the fire swept all through the tunnel. Lt. Friedline and four men died of burns that afternoon and four other men were seriously burned.

We went up to inspect the damage immediately. The pompon and the other machine gun pit were totally destroyed. A crew of engineers was working to extricate some of the bodies caught in the wreckage of the SL tunnel”.