Terminal ballistics: ID of WW2 amm holing a Thai bridge

Last but not least I wonder if you could cite the IAA (iaaforum.org) maybe? Or did I just miss it?

IAA is covered, no problem, my pleasure. So far, see my page 1a, notes A07, A07a; and page 1b, note D05Ƌ. IAA is also cited on page 2b in notes L27 and L30, but I haven’t uploaded that page yet.

I’m in the process of writing up what all I have to date on the two 20mm shell holes in the San Khayom bridge. I still have to deal with the 57mm shell hole (Point G).

I’ve not found as yet any aircraft, either Allied or IJAAF, operating over Thailand that used a 57mm cannon. On the ground, the Japanese had a Type 97 57mm Tank Gun, used in a Type 97 Medium Tank “Chi-Ha”. The gun would have been firing at the RAF Beaufighter or USAAF P-38 which was putting the 20mm holes in Points A and F of the bridge. The scenario in itself is not farfetched: 170 km SE at the Kaeng Luang Bridge, an enterprising Thai gunner using an anti-tank gun shot down a B-25. But at the San Khayom bridge, no Allied plane was downed though it might have been targeted.

I’ve found no record of tanks with 57mm guns or independently-mounted (jury-rigged) 57mm tank guns having been assigned or used at Lamphun; however, I see two possibilities by which such a tank or tank gun might have been present to defend the Lamphun bridge (plus a longer bridge just 6 km north):

  1. One of the main IJA supply routes for Burma followed the railroad from Bangkok to Lampang, 80 km south of San Khayom, where goods were transferred to road vehicles for transport to Kengtung, on to Mandalay, and then in 1944 to Imphal/Kohima, etc. There is also a story that an alternate supply route continued north by rail to Chiang Mai where goods were transferred for transport north into Burma. In both cases, rail transport came under heavy attack by Allied aircraft starting in early 1944 (there doesn’t seem to have been much recorded of attacks on road convoys). I’m guessing that those Allied air attacks might have damaged one or more tanks or their carriers sufficiently that they were abandoned along the way. Afterwards, enterprising Thais or Japanese might have salvaged a tank, or a tank gun, for anti-aircraft defense at Lamphun.
  2. In preparation for defending Thailand very near the end of the war, various IJA units were assigned to the general Chiang Mai area to meet any Allied ground attack from the north. IJA units included elements of the 4th and the 56th Divisions as part of the 15th Army which was itself headquartered in Lampang. All were essentially in position by June 1945. These units might somehow have acquired some Type 97 Medium Tanks, or at the least a Type 97 57mm Tank Gun, which found its way to the Lamphun area.

While this is totally speculative, I do have the hole in the bridge which records the diameter of the projectile, its angle of impact, and its bearing. If I could get a set of ballistics curves for the tank gun, I might be able to estimate the location of the gun, if it had been fired from the ground, and check that ground for any possible evidence (that’s where the metal detector will be a necessity).

So I ask, [color=#FF0000]does anyone have or know how to get ballistics curves for this Type 97, 57mm tank gun?[/color]

I thank you.

Great, I just thought it could be a good idea to have the IAA cited in a well researched article.

[quote=“islandee”]I’m in the process of writing up what all I have to date on the two 20mm shell holes in the San Khayom bridge. I still have to deal with the 57mm shell hole (Point G).

I’ve not found as yet any aircraft, either Allied or IJAAF, operating over Thailand that used a 57mm cannon. On the ground, the Japanese had a Type 97 57mm Tank Gun, used in a Type 97 Medium Tank “Chi-Ha”. The gun would have been firing at the RAF Beaufighter or USAAF P-38 which was putting the 20mm holes in Points A and F of the bridge. The scenario in itself is not farfetched: 170 km SE at the Kaeng Luang Bridge, an enterprising Thai gunner using an anti-tank gun shot down a B-25. But at the San Khayom bridge, no Allied plane was downed though it might have been targeted.

I’ve found no record of tanks with 57mm guns or independently-mounted (jury-rigged) 57mm tank guns having been assigned or used at Lamphun; however, I see two possibilities by which such a tank or tank gun might have been present to defend the Lamphun bridge (plus a longer bridge just 6 km north):

  1. One of the main IJA supply routes for Burma followed the railroad from Bangkok to Lampang, 80 km south of San Khayom, where goods were transferred to road vehicles for transport to Kengtung, on to Mandalay, and then in 1944 to Imphal/Kohima, etc. There is also a story that an alternate supply route continued north by rail to Chiang Mai where goods were transferred for transport north into Burma. In both cases, rail transport came under heavy attack by Allied aircraft starting in early 1944 (there doesn’t seem to have been much recorded of attacks on road convoys). I’m guessing that those Allied air attacks might have damaged one or more tanks or their carriers sufficiently that they were abandoned along the way. Afterwards, enterprising Thais or Japanese might have salvaged a tank, or a tank gun, for anti-aircraft defense at Lamphun.
  2. In preparation for defending Thailand very near the end of the war, various IJA units were assigned to the general Chiang Mai area to meet any Allied ground attack from the north. IJA units included elements of the 4th and the 56th Divisions as part of the 15th Army which was itself headquartered in Lampang. All were essentially in position by June 1945. These units might somehow have acquired some Type 97 Medium Tanks, or at the least a Type 97 57mm Tank Gun, which found its way to the Lamphun area.

While this is totally speculative, I do have the hole in the bridge which records the diameter of the projectile, its angle of impact, and its bearing. If I could get a set of ballistics curves for the tank gun, I might be able to estimate the location of the gun, if it had been fired from the ground, and check that ground for any possible evidence (that’s where the metal detector will be a necessity).

So I ask, [color=#FF0000]does anyone have or know how to get ballistics curves for this Type 97, 57mm tank gun?[/color]

I thank you.[/quote]

Hitting an aircraft with an AT gun is almost a miracle and I wonder of there are any more documented incidents like this. So using abandoned tanks (their main guns) for air defense is something extreme unlikely as they would have no military value in this role. Desperate shots of course can not be excluded.

Regarding that large hole in the bridge it should be kept in mind that it may not be a from a 57mm projectile at all nor has it to be related to the actual strafing run which produced the 20mm holes.
It might be worth to investigate what IJA units were deployed in the vicinity of the bridge (like 6km radius) during the war. That also brings us back to combat reports where one could try to investigate any other combat action in this area.

One thought! It is not clear to me that the P-38 20mm was fired separately from the .50Bs. I have seen the P-38 cockpit and do not remember noticing a selector switch to separately fire the two types of nose armament, but it is logical that there could have been one.

Regardless of whether a P-38 pilot had the ability to separately select the guns, I can’t imagine why a pilot would strafe a train, using only the 20mm. The .50Bs on B-25s were known to take large bits out of the side of Japanese destroyers according to accounts I have read, and were regularly used against trains in Europe with great success. The lack of .50 impact marks on the bridge would strongly imply that the attacking aircraft were Beaufighters. If there were .50 impacts they would strongly imply a P-38, or more than a single attack. The USAF Museum in Dayton Ohio could likely answer the question on a P-38 selector switch, though the existence of such a switch is not central to your research.

Just some random thoughts.

Cheers,
Lew

If you haven’t already done so, a search of the UK National Archive records for 211 sqn may prove useful. While researching RAF 115 sqn, I was absolutely amazed at how much information was contained in the RAF combat reports and operation records books. I shouldn’t have been surprised but in a number of cases, statements made on various websites were either not supported by the official records or were simply wrong.

NATO Dave

[quote=“Lew”]One thought! It is not clear to me that the P-38 20mm was fired separately from the .50Bs. I have seen the P-38 cockpit and do not remember noticing a selector switch to separately fire the two types of nose armament . . . .
[/quote]
Rather than a selector switch, there were two separate buttons on the front and back of the control wheel at about 2 o’clock. The cannon trigger button was on the pilot side of the wheel. The machine gun button was at the same 2 o’clock, but on the “forward side of the wheel”. See Pilot’s Flight Operating Instructions for Army Models P-38H Series, P-38J-5 and F-5B-1, Figure 4, Item 12, page 3.

The thought should appear applicable to both P-38s and Beaufighters? In any case, why the pilot didn’t go in with all guns blazing is an unknown. Or, if he did, why there isn’t evidence of same in the bridge, another unknown. Perhaps some of the markings on the bridge which are so obscure that I’ve arbitrarily classified them as fabrication errors (and disregarded them) are ‘dings’ from 50s, but that certainly wouldn’t fit the damage 50s did to Japanese destroyers, which probably had some armor plate while the San Khayom was made of (soft) structural steel.

None documented at least in Thailand that I’m aware of. Which I suppose could be cited as verifying the extremely long odds involved which made the event “almost a miracle”.

Nor can desperate measures: I recall reading that Allied pilots witnessed Japanese troops, rather than running for cover during a strafing run, apparently ordered out into the target area to shoot at incoming enemy aircraft with anything available, from pistols to rifles to MGs, and whatever else could be brought to bear. The Japanese army, at least the officers giving such commands, had a different perspective on the value of the lives of their charges from that of Allied and German military personnel.

Very true: I must include that in my writeup.

Elements of the IJA’s 4th and 56th Divisions were called into the northwestern Thai provinces, commanded by the 15th Army relocated to Lampang, in the last days of the war to defend against an Allied invasion from the north (Burma’s Shan States). I must add that detail to my writeup. There is even an old Thai in the village who recalls four or five IJA troops having been bivouacked in the local temple; but other details, if he ever knew them, are lost. The official Japanese military history of the war (I have those volumes which deal with Burma and Thailand), can only deal in relative generalities regarding that activity. Practically speaking, the language barrier limits my digging further. And even if unit records exist, they probably won’t be in any greater detail than Allied records which are notably absent when it comes to details like who exactly strafed a train 7km southeast of Lamphun rail station, with detail about a bridge not relevant and probably not mentioned. With the disorganization of the IJA in those latter days of the war (and the Allies broadbrush command to its aircraft to attack ‘targets of opportunity’), I don’t think such details exist.

In looking back over my efforts, I didn’t have any success with an inquiry about 211 Squadron to the UK National Archives — I used the ‘Discovery’ webpage in making the query.
Are you talking about on-line records or hardcopy ones? If the former, (even at this late date) I would appreciate some hints on how to better access the system. If the latter, I don’t have the funds to visit the UK.

Try the following:
Go to "UK National Archives"
Then "Online Records"
Then "Air Force"
Then “Royal Air Force Operations Records Books” http://www.nationalarchives.gov.uk/records/raf-operations-record-books.htm

Once in the last page, you can search by sqn number and time frame. I did a quick search and found multiple files for 211 sqn. The files can be downloaded for a little over 3 GB pounds per document. To do this you have to create an account but once this was done I had no problem downloading the files.

Hope this helps

NATO Dave

I thank you for the guidance.

I count 66 files as possibly relevant (that count would include 177 Squadron as well as 211); that totals around £200 — rather dear just to find one relevant record; but all of those records which included missions over Siam / Thailand would of course be of possible value to me.

A problem for me in the example record of events provided on the Archives website is the anonymity of the targets beyond names of some rather large cities (Berlin, Leipzig, Frankfurt): TI markers, TI Greens, TI Red, Wanganui flares, Primaries, targets, Sky Markers, Green Stars, etc.

Naming locations in Thailand, where target towns (excluding Bangkok, Chiang Mai, and Lampang) were quite small, might not be such a problem. But, as I’ve wondered elsewhere on this board, I don’t think I’m going to see a description “strafing train 7km (4mi) south of Lamphun”, with the distinguishing feature for me being the bridge, which was irrelevant to the shooter and thus probably not mentioned.

[quote=“EOD”]Maybe you can contact US and UK archives for further research?[/quote]USAF: I must check on items new since I last made an order.
UK: See just previous comment.

[quote=“EOD”]Are you cooperating with a govt. museum in Thailand maybe? If so they may grant you an explicit permit for doing some detecting around the bridge?[/quote]No, but that’s a good idea. However, I need to get the detector first so that I can move quickly if they agree (before second thoughts cloud their thinking).

[quote=“EOD”]Did Japanese trains have installed AA guns?[/quote]I’ve only found one relevant entry, in a report dated 12 Jan 1945: “A new development was encountered at UTTARADIT and LAMPANG in the shape of flak-wagons, apparently attached to military trains. No flak-wagons had previously been identified in the SEA theatre except on the BURMA-SIAM line in April 1944.” (my ref: A8044 p0557) Nothing further. If used, hopefully the guns they carried would have been directed higher than the bridge.

CORRECTION 05 Nov 2014: Steve Darke’s Thai Air Accidents lists comment for a P-38 downed on 12 Jul 1945:

“Hit by small arms fire whilst on a reconnaissance mission and crashed approx. 12 miles NW of Lampang airfield [18°25’N, 99°25’E]. Pilot 1st Lt. Theodore H. Demezas bailed out [MACR 14710]
(Note: Lt. Buntao Punsri operated a flak gun wagon at Lampang Station and claimed to have shot down a P-38. . . .”

So there was one shootdown by a flak-wagon, which was located at Lampang Station. Apparently assigned to protect Lampang rail station is reasonable: the railyard was regularly being targeted in the latter days of the war. Why a mobile gun was stationed there, a regular target, is less clear: the gun should have been mounted on the ground.

[quote=“EOD”]Maybe you can get photos of 20x110 HS cartridge (AP, “ball” and HE types) to show them with the penetrated bridge parts or the diagrams of the cartridges?[/quote]I had earlier used some cross-section diagrams to try to illustrate how the teardrop shaped Hole A might have been formed by a 20mm shell; but the shell dimensions didn’t work. Here are some of the scenarios I played with: Sandbox. Now I would guess that the violence of the impact of the projectile point simply tore the metal above / beyond the point of impact. And possibly below also, with that being obliterated by the subsequent passage of the main portion of the shell. But that’s just a guess. I could find nothing in ballistics literature to support the idea.

Islandee, when contacting your museums you may refer to your website and the research you have done so far and if appropriate even link the duscussion here so the people in charge get an idea of how serious and detailed your work is and that some remaining questions can only be solved by detecting the area for spent cases. Just a thought.

What an interesting thread! The question comes to my mind why would the plane be shooting at the bridge?

Its not an effective tactical way of destroying a bridge so (IMO) probably they were shooting at somebody or something on the bridge. There still has to be a reason why, operating that far from home its unlikely to have just been random harassment. Every mission would have had a purpose.

This approach may be more useful at giving some indication of a date because wars go on for years but actual engagements are less frequent and usually linked to other specific events identifiable locally. So maybe a look at the slightly bigger picture might produce a few ideas that could then be narrowed down.

I would say start Sept/Oct 1945 after the British* landed. That’s a likely time to be taking out bridges

*Indian troops under British command

Vince, I think the target was a train or troops on foot which passed the bridge.

I’ve attempted to finalize my webpages on this subject, but am of course still interested in feedback. There are some topics which I leave open: some seem more effort than is warranted; others can have no answers; a metal detector is on order as a long shot.

I very greatly appreciate the thoughtful direction I’ve received from various contributors on this forum: I think I’ve learned a good bit about ballistics and have hopefully corrected all of my naive statements in my first draft aired here in early March.

My treatment of this subject has grown to 11 webpages (which start here), and offers more detail than the average reader probably cares to wade through. As a result, I’ve started the subject off with a single page condensation — it’s a long page, but just one.

Again, well done! Let us know if you find any new facts or related reports.