Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)

OK, you guys have me confused (not hard to do really but still...) so what did happen over Port Moresby in 1942? Is there a reasonable set of numbers for aircraft lost for both sides that can give me a better picture of the whole year? As a kid I read that terrible Caiden book about Sakai, as I got older I realized how much fiction that was, but I still want a better picture of what happened. So any info or references you can give I'd greatly appreciate.

Thanks

parsifal said:

On paper, P-39 exchange rates in the air with A6M looks quite favourable. Unfortunately most accounts are based on post war claims data by the US forces, which ended up being summarised in the USSBS. Problem is, the claims, like all claims data is generally wildly inaccurate. As an example, the first raid in which P-39s rose to fight A6Ms over Moresby occurred May 9 1942. I don't think there was a combat between A6Ms and P-39s before that date in this TO. Allies claimed three A6Ms downed for no losses in the air. problem is, there were no losses to the A6Ms, not even a scratch. this kind of inaccurate reporting continued for the entire first deployment of the 8FG to the end of July.

To be fair, I don't think it was the aircraft mismatch alone. Average approach altitude for the IJA bombers was 24000 feet, coming in over the owen Stanleys. Because of those mountains, early warning until the end of 1942 in this TO was limited to about 40miles. there wasn't time for the P-39s to reach them, and even them at 24k the p-39s handled like pigs, hence their nickname. Most days the p-39s just took off in the opposite direction....better to be airborne and out of harms way than airborne targets I guess.

The second unique factor to consider at this time was the quality of the pilots. it was the tainan air gp, including the famous lae wing. Lae Wing included such greats as Sakai and nishizawa. In the whole of 1942, only two pilots of this super elite group were lost in the air (according to one source at least...put it this way, there were just 15 a/c and about 39 pilots, and nearly all of these guys fought on in later campaigns. in 1943-4, where the wing member did suffer a lot more fatalities. .For 1942, there were other losses over moresby which I haven't tallied from Rabaul.

For me guys, claiming the p-39 was fully the equal to the A6M over port morersby does not hold up to scrutiny.

Click to expand...

Since this thread is titled "P-39 vs. German Fighters" I have attached a graph of P-39 vs. Zero performance. Graph is for a P-39K but is almost exactly the same as for the D model. Zero performance is noted by the small black circles.
As the graph shows, the P-39 had a fairly significant speed advantage but the Zero climbed better. Of course the AAF pilots did not know the performance of the Zero until results of tests of the Alaskan Zero were distributed in the fall of '42.
The little curved line in the climb section between 12500' and 15000' denotes the reduction from 3000rpm (combat) to 2600rpm (max continuous) at the 5 minute mark. The Allison engine was rated at military (combat) power for 5 minutes, so after that time the power was reduced to max continuous for the remainder of the test climb.
Of particular interest is the P-39 climb rate at 1000fpm with drop tank. As we can see this occurred at about 19000'. The 1000fpm is significant because most observers consider this the operational or combat ceiling since climbing at less than 1000fpm was both dangerous and hard on the engine as it was operating at almost full power.
The Japanese Bettys came in between 18000' and 22000', sometimes a little higher but I have a hard time believing they ever got to 30000'.
So, virtually every combat involved the Japanese having the altitude advantage and the AAF in a defensive posture.
The P-39s (with drop tank) on patrol (since there was little early warning) could (and did) get to 23000' and intercept but it was very difficult.
After sighting the enemy and dropping their tank, climb was much easier. Plus combat climb at 3000rpm was normal since if you were in combat at 3000rpm and you needed to climb you didn't reduce power to 2600rpm. The reduction to 2600rpm was for the performance test. Climb at 3000rpm was pretty close to the Zero climb rate.
In summary, the P-39 was about 40mph faster than the Zero above 15000' and could climb almost as fast at combat power. Disadvantage was maneuverability and range, with the big disadvantage being the highest cruising altitude with drop tank being below the Bettys and their Zero escort.
The 5 minute combat power restriction was increased to 15 minutes at mid year '42 along with finally discarding the power robbing port backfire screens. Then by December '42 the P-39N was available which would substantially outclimb the Zero at all altitudes. Just my 2 cents worth.

In the hot and humid conditions that defined the Port Moresby area, the density altitude at sea level could be 5,000 feet. This means a plane flying at 23,000 above sea level might perform like it was flying 5,000 feet higher under standard conditions. That being said, the density altitude was the same for all combatants, so the Japanese planes would be facing the same issue.

Parsifal,
Ruffato uses the Kodochosho records of all IJN air units in the Southeast Area to make his assessments. He does not rely on just US and Australian wartime claims, but compares claims vs reported losses of both sides, giving a score of claims vs actual losses. You should read it. He's an Italian so has no iron in the fire.

Some known details of the 8th fighter group in the SWPA

From the Australian @ war research site

35th fighter squadron
The 35th FS sailed to Australia with the rest of the 8th FG on an old cattle boat called "Maui", departing the US leaving late January 1942. They arrived in Brisbane on 6 March 1942.

The 8 FG were equipped with P-39's assembled at Amberley west of Brisbane Brisbane. These P-39's assembled at Amberley were originally intended to go to the Philippines but the convoy was diverted to Brisbane. The 35 FG (not FS) had earlier been equipped with P-39's also assembled at Amberley.

Elements of 35 FS moved to Woodstock just outside of Townsville on 26 April 1942 on their way to Port Moresby, where they arrived on 30 April 1942. They later returned to Woodstock on 29 June 1942 having suffered heavy losses whilst at Moresby for various rest and re-equipment tasks. They relocated to Garbutt, Townsville on 27 July 1942 and then moved to Milne Bay in New Guinea on 18 September 1942.

They relocated to Mareeba airfield on 24 February 1943 after again having suffered further heavy casualties and finally moved to Port Moresby in New Guinea on 10 May 1943.

"Eagle Farm 1942 - Airacobra Assembly" by Brian Creer (note these Airacobra's were actually assembled at Amberley airfield)

36th Fighter (Pursuit) sqn)

The 36th FS of the 8th FG of the USAAC arrived in Brisbane on 6 March 1942.

They moved to Lowood A/B (an RAAF training field about 60kms west of Brisbane) on 13 March 1942. They relocated to Antill Plains airfield near Townsville on 4 April 1942 where there were 2 landing strips.

They moved to Port Moresby, arriving on 26 April 1942 (another source gives the date as 30 Apr 42). They later returned to Townsville having also suffered more than 50% losses whilst engaged area on 30 June 1942 for various rest and re-equipment tasks.

The History of the 36th Fighter Squadron shows that ground elements of the 36th Fighter Squadron arrived back in Townsville on the ship Tasman on 30 June 1942. They boarded a train and were taken to Antil Plains airfield (20km south of Townsville). They boarded trucks and were taken to the camp formerly occupied by the 40th Squadron. They were met by the pilots and the men who had returned from Port Moresby by air transport and the men who had been on duty at Horn Island since 1 April 1942. The 36th then moved to Ross river Airfield, Townsville arriving there on 2 August 1942 where they used the new runway that was nearing completion on the edge of Townsville.

They moved to Milne Bay in New Guinea on 18 September 1942. On 22 February 1943 they moved to Mareeba airfield in north Queensland and moved to Port Moresby in New Guinea on 22 May 1943.

80th Fighter Squadron
The 80th FS moved to Lowood near Townsville on 28 March 1942 (another source shows the date as 13 Mar 42). By 10 May 1942, the 80th Pursuit Squadron had moved from Lowood to Petrie just north of Brisbane where they trained for combat for 2 months.

They moved to Port Moresby, arriving on 20 July 1942. They relocated to Milne Bay on 8 November 1942. They moved to Mareeba airfield on 6 February 1943 to re-equip with P-38 Lockheed Lightnings. They then moved to Kila airfield at Port Moresby on 21 March 1943.

On 20 July 1942 twelve P-400's of the 80th flew to 7 Mile air field outside Port Moresby, New Guinea. They participated in missions to Buna strafing Japanese barges, intercepting Japanese aircraft, escorting Douglas A-24 divebombers to Buna, and escorting transport and bombing missions in the Buna and Kokoda Trail areas, carrying out dive-bombing missions at Myola Lake.

On 15 May 1942 the designation of Pursuit Group changed to Fighter Group.

By 10 November 1942, the 80th FS moved from Seven Mile to Turnbull Field at Milne Bay where they were employed as escorts for air transport and shipping. Not the mark of an overwhelmingly competitive fighter, by any measure!

On 28 January 1943, the 80th FS was relieved by the 36th FS. On 6 February 1943 the 80th moved to Mareeba in north Queensland. Here they converted from their P-400's to P-38 Lightnings.

The 80th moved back to New Guinea in about March 1943 now with p-38s, , and eventually moved to Borneo, then the Celebes Islands, then the Netherlands East Indies and the Philippines and finally Okinawa on 29 August 1944.

A few of the more well known Aces of the 80th Fighter Squadron were Major Jay T. Robbins (22 confirmed kills) and Major Richard I. Bong (40 confirmed kills). Between them, based on these '"confirmed" kills, they had managed to destroy the entire tainan AG severasl times over!!!!!!!!

There is no possibility that any element of the 8FG ever engaged Zekes before 26 April 1942. They did not enter combat until May 1942 in the defence of Moresby. This matches other sources not so one sided as others are relying on …..

5 P-39s of the 36th PS arrived at Port Moresby on 5 April 1942, led by Col "Buzz" Wagner as part of the first flexing of USAAF muscle, as it were, along with B-26s of the 22nd BG and B-25s of the 3rd BG. This is attested in several Australian war diaries. Strangely, it is not mentioned in Attack and Conquer, the popular history of the 8th FG by Stanaway and Hickey.
Two pilots, 1/Lt Louis Meng and 1/Lt Charles Faletta, were airborne the next day when the daily Japanese raid came in. Meng engaged the bombers but did not score. Faletta tangled with Zeroes but made no claims. No. 2 Chutai of Tainan claimed two P-39s, while WO Yoshino Satoshi claimed two kills and FPO2c Tan Yukihisa claimed another. the RAAF lost two Kittyhawks, F/Lt Les Jackson ditching in Bootless Bay and F/O Edmund Johnson bellied into a swamp. Both pilots survived.
6 April 1942 is notable because it was the combat debut for the B-26, B-25 and P-39.

There aren't any Australian sources that place any USAAC P-39's in operational condition at Moresby in early april. They may have staged there due to mechanical difficulties , though that is pure conjecture on my part. I have no P-39's at Moresby at this time. none that I know of at least. Some sources place an advance force of 5 p-39s at Horn Island (some hundreds of miles to the west of Moresby) from 5 April. These saw no combat that I am aware of and lost at least one of their number to non-operational causes.

From this source on "buzz" wagner deployment to Australia I could find no mention of this advance deployment to Moresby:

1st Lieutenant Boyd D. "Buzz" Wagner, later Lieutenant Colonl Wagner in Australia during WW2

But this web page did include reference to a report he made concerning the P-39.

"In May 1942, Lt. Col. Boyd "Buzz" Wagner forwarded a report "Fighter Aircraft Report to USAFIA, 21 May 1942" to the Commanding General USAFIA on the P-39 Airacobra. Wagner criticized their low rate of climb and excessive wing loading, which precluded aerial combat with the Zero. He also criticised the vulnerability of its liquid-cooled engine and its constant problem with the guns jamming. The .30 caliber wing guns and the 37mm propeller-mounted cannon jammed repeatedly. The two cowl-mounted .50 caliber machine guns were the only reliable guns. Wagner felt that the P-39 was "10 percent better than the P-40 in every respect except maneuverability below 18,000 feet." "

A different website on his biography

Boyd D. Wagner Archives - This Day in Aviation


"Lieutenant Wagner was promoted to the rank of Captain, A.U.S., 30 January 1942. On 11 April 1942, Captain Wagner was again promoted, bypassing the rank of Major, to Lieutenant Colonel, A.U.S. He was assigned to the 8th Fighter Group in New Guinea. On 30 April 1942, while flying a Bell P-39 Airacobra, Wagner shot down another three enemy airplanes. In September 1942, Colonel Wagner was sent back to the United States to train new fighter pilots".

Again, no mention of him being deployed to Moresby in early April 1942.


Based on this link

https://buzzwagner.wikispaces.com/file/view/wagner+bio.pdf

Wagner achieved his 8th kill on the 30 April 1942 with the claimed loss of three Japanese aircraft over NG. Between end of December and the end April he had achieved no kills according to this source



This source:

Shadow box

also gives his 5th victory as December 16 1942, then in hospital until the end of april before scoring those 3 "magical" victories on the 30 April. I say magical because I cannot find any corresponding losses from the Japanese units engaged at the time.

A summary of most of this information can be found at the the pacific Wrecks site

Pacific Wrecks

but it is not complete. You need to access the war diaries by Tatsuo Matsuo and Shindo as well as George henry Johnston "War Diary"….the nearest we have to primary sources

the following raids were recorded over Moresby

March 31, 1942
A single G3M piloted by a Lt Harada flew a suicide mission from Lae to Port Moresby, not returning. The attack-bomber made a vertical dive at Waigani Airfield, Port Moresby, and crashed. Seven of the crewmen were discovered and recovered. It was a real suicide dive and crash. The bomber crew's plane was hit on a bombing mission to Clark Field, Luzon in the Philippines, and made a forced landing on the way back on 12 December 1941. They were captured but rescued later when the Japanese occupied the islands, but they were not allowed by the command and were forced to fly suicide missions during the succeeding operations. Ironically, they survived every time they flew. On this date, they determined to kill themselves on a single-plane mission.

War Diary 1942 (see note below) page 46:
Jap Bomber falls to pieces! An extraordinary incident this afternoon. A big Japanese bomber was overhead on reconnaissance in cloudy weather - the same plane that tried unsuccessfully to drop bombs yesterday. None of our fighters went up and the AA never fired a shot, but suddenly the bomber was seen to be falling after losing part of a wing or tail plane. It crashed into the hills in a big cloud of smoke.The bodies of the crew were found in the wreckage - including the body of a high ranking Japanese officer in full uniform and wearing his sword!"

April 7, 1942 (Raid 24)
Moresby raided today by Jap bombers and fighters. Several were damaged, but one of our fighters was shot down and another missing. One pilot was saved. Parties looking for Jap pilot who parachuted during Sunday's raid into heavy jungle country.

April 10, 1942 (Raid 25)
Seven 4th Kokutai G4M1 Bettys and six Zeros are intercepted by nine 75 Squadron P-40E's. Lost is a G4M1 piloted by Kobayashi. The bombers were escorted by six A6M2 Zeros. Over the target, intercepted by nine RAAF 75 Squadron P-40E Kittyhawks. Shot down over the Owen Stanley Mountains, going down in a flat spin with smoke streaming from the tail. (verified by 4th Kokutai records according to Shindo)

"War Diary" entry "Apparently as a reprisal for yesterday's raid on Rabaul, seven Jap bombers and six Zero fighters raided Moresby this morning. They dropped their bombs ineffectively when our Kittyhawks tackled them and made off for home at high speed. Our fighters chased them right out of Papua into New Guinea, fighting a series of running dogfights for over half an hour. One Jap bomber was caught in the guns over the terrible jungles of the Owen Stanley Range an went down in a flat spin with smoke streaming from the tail. All our planes got back safely."

April 17, 1942
Zeros claimed 6 P-40s destroyed in raid. On the way to the target, A6m2 Zero piloted by Sakai is lost in the Owen Stanley Mountains. Took off from Rabaul on a mission to attack Moresby. On the way to the target over Owen Stanley Mountains, PO2/c Sakai lowered his altitude staggeringly and fell into the jungle after the Zero formation crossed the spine of the Owen Stanley Range, on the south side of the spine. Possibly, this loss was due to an oxygen failure (from Tatsuo Kamino; Winged Samurai, Page 88) In the combats over Moresby RAAF P-40E Kittyhak A29-28 is damaged. No losses to the Japanese according to Tatsuo Kamino.

April 24, 1942
In the morning, twelve A6M2 Zeros of the Tainan Kokutai attack Port Moresby, six dog fighting with RAAF 75 Squadron P-40 Kittyhawks and six attacking other aircraft and bombers. They claimed nine shot down (five P-40s, one P-39, two B-26s) and damaged a PBY. In fact, they destroyed two B-26s [one is B-26 "Hello Angel" 40-1448), PBY A-24-5, and 3 x P-40E Kittyhawks RAAF. One further P-40E is damaged. No p-39s were present according to the war diary.


April 25, 1942
Fifteen A6M2 Zeros fly a fighter sweep over Port Moresby. Four strafe 7-Mile Drome. Destroyed on the ground is B-17E 41-2641.

April 26, 1942
(Raid 32) 2350-0015GMT/26 Port Moresby area is attacked by nine Type 99 (Nell) heavy bomber with escorting A6M2 Zero fighters approached from north made one run over Kila Drome (3-Mile) at 22000' . Approx. 90 bombs mostly H. E. are dropped near dispersal area. Two 3rd BG A-24s are destroyed one other completely unserviceable. No other damage no casualties. P-40s did not intercept. No record of any p-39 activity 9because they aren't there yet!!!) The partly completed Rarona (30 Mile Drome) near Galley Reach is also bombed. Reference: Combined Operational Intelligence Centre Log for 26 April 1942 New Guinea Force - HQ & Air via Edward Rogers (He is currently the historian for the 3rd Bombardment Group and is completing work on their WWII history, Harvest Of the grim Reapers vol I - He has also worked with the 40th Fighter Squadron Association to research the histories of their MIA pilots).

April 28, 1942
(Raid 33) Six Kittyhawks took off at 1036K to intercept eight Japanese bombers escorted by A6M2 Zeros over Port Moresby. P-40E A29-8 piloted by S/L Jackson and F/Lt B M Cox piloting P-40E A29-47 failed to return. F/Lt Cox listed as missing. F/O Brereton was also wounded in this action, and his aircraft severely damaged, though returned to base. Lost is A6M2 piloted by Yoshimitsu Maeda who later taken POW.

Maeda took off from Lae Airfield on a morning combat air patrol (CAP) and landed safely. Later that same day at 13:00, again took off from Lae along with a Zeke piloted by Arita in pursuit of a "Lockheed Hudson", in fact B-25C Der SCHpy 41-12496, which was lost, Arita claimed it as shot down, but Maeda did not return and was declared missing. If fact, Maeda became separated, crossed the Owen Stanley Mountains and ended up east of pt Moresby when he spotted a ANGAU ship [MV Laurabada] east of Abau. As he turned to strafe it, and hit a coconut palm on Otamata plantation and made a crash landing in the plantation. Maeda survived the crash landing unhurt but stunned from the impact. He was taken prisoner. The official Japanese report said Maeda was ill due to oxygen starvation, and that is why he made a forced landing. Other reports incorrectly state this Zero was hit by Allied gunfire and the pilot made a forced landing with the engine running at the time.

Returning to Raid 33, one of the Japanese bombers drop four bundles of letters from Australian POWs at Rabaul. The bundles landed near 7 Mile Drome. Three bundles of letters were located and the last bundle was found later. Inside were 395 letters (325 military, 70 from civilians) wrapped in khaki cloth with a 4' streamer attached to each with a message in English "Any person found return to Army Headquarters Port Moresby".

No raids recorded, no losses recorded until May 9th…so much for 3 victories on the 30 april……..

May 9, 1942
A6M2 Zeros from the Tainan Kokutai strafe 3-Mile Drome and 7-Mile Drome, damaging several A-24s. It is later cannibalised.

May 12, 1942 at 0743
(Raid 46) Eleven A6M2 Zeros strafed Bomana Drome and M. G. positions in area. No damage No casualties. Intercepted by 13 P-39s. claims of two Zeros down. Investigating possible crashes. One P-39 temporarily unserviceable. Two P39's missing. Tatsuo Matsuo or Shindo record any losses to Japanese forces on this day.

0850 Gun on hill behind Bde. H.Q. reports large column Black Smoke 7 to 8 miles on bearing 320 [degrees] and 321 [degrees]
1350 Reported Crash of Aircraft
Paga - Bearing 46 [degrees] - distance 10 miles
Tuaguba - Bearing 44 [degrees] distance 10 miles
1800 1 P39 missing in Raid 46 found at VARI VARI 1 mile inland. Pilot safe. (Reference: New Guinea Force Diary).
(This is the first raid recorded as being intercepted by the P-39s of 8FG)

War Diary 1942
This book is the wartime diary of Author George Henry Johnston at Port Moresby. It records his daily notes about happenings, including Japanese air raids and movements of Australia and American forces. The diary is an interesting read, that begins in the darkest days of early 1942 when the Japanese dominated the skies and bombed Moresby daily at will, including the first recorded bombing mission:

"February 3, 1942 (Raid #1) Six Japanese flying boats bombed Port Moresby 3-3:30am, although no great damage was done this set the stage for the future living conditions in town. One man is KIA."

The book conveys the feelings of men on the ground who lament about their forgotten status, the "Mice of Moresby" and gripe about when supplies or when P-40 Kittyhawks to defend the town will arrive, dubbed 'Tommorrowhawks' or 'Neverhawks' by the men on the ground awaiting their appearance.

As time progresses, the diary records the changes in the tactical situation: first the arrival of P-40 Kittyhawks of 75 Squadron, that for the first time contest the air raids. Later, the arrival of American reinforcements.

The diary records a tally of air raids against Port Moresby, numbering each raid and providing a summary.

Although some details in the diary have proven to be incorrect with the hindsight of history, it is a compelling look into the day to day lives of men on the ground at Port Moresby.

parsifal - Once again, many thanks, you've (again) given me some reading material to fill out my knowledge.

*EDIT*
OK, so I'm going through the Pacific Wrecks timeline but it seems I can't get a handle on actual losses from it. I see where sometimes an A6M2 is claimed to be seen trailing smoke in a dive but there isn't corresponding data from the Japanese side for actual losses, although it seems at times there is.

Yeah, I might have to rethink what I wanted to do with this.

tomo pauk said:

There was no belly armor on the P-39.
In order to compensate for lighter front end, remove the rearmost armor plate (the one behind the oil tank) and replace it with aluminium type. Keep the number of radios to one. Less gun & spent cartridge openings = less drag, so indeed remove the wing guns. Keep the fuel tankage, radius is is already short for Pacific.



Wing gus are as close to the centre of lift as possible.

Click to expand...

yes there was. i have a pressed inch think belly armor plate off one of my planes

the P-39 was not suited to png because of the hot climate and high mountains, but at low level it will run rings around anything except an a6m

fiftycal said:

yes there was. i have a pressed inch think belly armor plate off one of my planes

Click to expand...

Interesting.
Hopefully you will be so kind to post a picture, and/or part number, and/or schematics pertaining the inch-thick belly armor plate that was in series production for a P-39.

fiftycal said:

the P-39 was not suited to png because of the hot climate and high mountains, but at low level it will run rings around anything except an a6m

Click to expand...

See post #62 this thread.

Peter Gunn said:

parsifal - Once again, many thanks, you've (again) given me some reading material to fill out my knowledge.

*EDIT*
OK, so I'm going through the Pacific Wrecks timeline but it seems I can't get a handle on actual losses from it. I see where sometimes an A6M2 is claimed to be seen trailing smoke in a dive but there isn't corresponding data from the Japanese side for actual losses, although it seems at times there is.

Yeah, I might have to rethink what I wanted to do with this.

Click to expand...

Its not the easiest website to navigate, but the information on the known losses is there. sometimes you have to hit the active links to bring up the particulars of a given combat or loss.

Parsival,
Luca Ruffato relied on the Tainan Kokutai kodochosho as well as those of other units from the Japan Center for Asian Historical Records, not to mention the allied unit records, diaries of combatants from both sides etcetera, for his work. If you want to ignore the official unit records, that's fine. I'll stick with the recorded facts.
You seem to have an axe to grind vis allied kill claims, but seem to accept the Japanese/German claims at face value. What's your beef?
If you haven't read Eagles of the Southern Sky yet, I suggest you do it. The book does it's best to be a sober analysis of the air war over New Guinea during April - November 1942, recording what the combatants claimed and what they reported as their own losses.
And remember, he is quoting the original sources, not somebody's recollection of what happened forty to fifty years ago, although he does that too for color.

5 April 1942 - FPO2c Yoshi'e Takuro shot down by F/Lt Les Jackson, 75 Sqn RAAF, NE of Port Moresby, bailed out, MIA.
7 April 1942 - FPO2c Tan Yukihisa shot down by A-24 defensive gunnery, 8th BS, 3rd BG near Lea, KIA.
11 April 1942 - Flyer1c Tanji Jufuku shot down by FO Pete Masters, 75 Sqn RAAF, near Lea, KIA.
17 April 1942 - FPO2c Sakai Yoshimi crashed in mountains after fight with 75 Sqn RAAF. MIA.
28 April 1942 - FPO3c Maeda Yoshimitsu crashed Otonata Plantation while strafing, POW
30 April 1942 - FPO2c Izumi Hideo shot down by 8th FG P-39s near Lea. KIA.
1 May 1942 - FPO2c Arita Yoshisuke shot down by 1/Lt Don McGee, 36th FS, 8th FG over 7 Mile Field, KIA.
2 May 1942 - Flyer1c Kawanishi Haruo shot down near Port Moresby by 1/Lt Don McGee, 36th FS, 8th FG, KIA.
13 May 1942 - FPO3c Honda Toshiaki shot down by 8th FG Airacobras near Lawes Mountain, KIA.
14 May 1942 - FPO1c Oshima Toru collided with 8th FG Airacobra near Port Moresby, KIA.
16 May 1942 - FPO2c shot down near Lea by defensive fire while attacking B-25s of 3rd BG, KIA.
17 May 1942 - FPO2c Ito Tsutomu crashed in mountains returning to Lea after hit by ground fire at 12 Mile Drome. POW
17 May 1942 - LT(jg) Yamaguchi Kaoru crashed into mountains after hit by ground fire at 12 Mile Drome, KIA.
25 May 1942 - Flyer1c Watanabe Masao crashed into sea while attacking B-25s of 3rd BG off Salamaua, probably hit by defensive fire. KIA
29 May 1942 - FPO2c Komori Hisao killed by Australian patrol near Iwaia after forced landing following fight with 8th FG Airacobras. KIA
1 June 1942 - WO Miyakaze Gitaro shot down by Cpt Bill Bennett, 35th FBS, 8th FG near Port Moresby, KIA
9 June 1942 - WO Yoshino Satoshi shot down by 2/Lt Curran Jones, 39th FS, 35th FG near Cape Ward Hunt, KIA
9 June 1942 - FPO1c Kikuchi Sakyo shot down by 2/Lt Dick Suehr, 39th FS, 35th FG near Cape Ward Hunt, KIA
16 June 1942 - Flyer1c Hidaka Takeichiro shot down by 1/LT Francis Royal, 39th FS, 35th FG, near Cape Ward Hunt, KIA
4 July 1942 - Flyer1c Suizu Mitsuo collided with B-26 near Lea, KIA
11 July 1942 - FPO3c Suzuki Matsumi shot down by defensive gunnery from 19th BG B-17s. KIA
20 July 1942 - 4 pilots lost in bad weather between Lea and Rabaul, FPO1c Kobiashi Katsumi, LT(jg) Kurihara Katsumi, FPO2c Miya Unichi, FPO3c Onishi Yoshima MIA
These are the reported losses April - July of the Tainan Group. Credits based on Ruffato's analysis of Allied claims during the period.
Yes the US and Australians claimed WAAY more than these, but then, so did the Japanese.
Example 9 June 1942 - 22nd BG claimed 11 Zeroes, 35th FG claimed five, and the Japanese claimed four B-26s. Actual losses were 1 B-26 shot down (8 KIA), one force landed at Moresby (repaired/non-operational), one P-39 force landed out of fuel, and two Tainan Zeroes lost with their pilots.

From Weapon of Denial - Air Power and the Battle for New Guinea, Gary Null 1995; Air force history and museum program
https://media.defense.gov/2010/Oct/06/2001329753/-1/-1/0/AFD-101006-028.pdf

"…….on March 31 U.S. Army Air Forces (USAAF) in the Southwest Pacific Area sent the 8th Bombardment Squadron to assist the small Australian garrison at Port Moresby with some Douglas A-24 dive bombers, the Army's version of the Navy's famed SBD Dauntless, which would soon be victorious in the Battle of Midway.

A month later, the 8th Fighter Group arrived, equipped with new Bell P-39 and P-400 Airacobra fighters-the latter export models of P-39s intended for use by the Royal Air Force (RAF). The fighters made their first attacks against Japanese forces 200 miles north of Port Moresby at two sites 19 miles apart on the western shore of the Huon Gulf-Lae, a

major enemy supply base, and Salamaua-on April 30. On May 15 Port Moresby-bound Australian reinforcements were dispatched"

So this might reveal the mystery of the April 30th combats. However this source again confirms that there were no p-39s present at Moresby 5 april. This source again confirms that they were not present for the whole of april. As previously stated, they may have been deployed at horn Island, in very small numbers. The article does suggest that an attack was carried out at two sites within the huon gulf area, suggesting to me they were ground strikes of some description.

There certainly weren't any P-39s at Milne Bay

On Page 10 of the article I found the following:

"The potential of air attacks against enemy communication lines first became apparent in April 1942. Light bombers began striking Japanese forces on the Papuan peninsula, and by the 30th, twenty-six P-39s of the 8th Fighter Group were strafing aircraft and fuel tanks around Lae and Salamaua."

The Japanese losses attributable to 8FG air activity are shown in bold for the date
5 April 1942 - FPO2c Yoshi'e Takuro shot down by F/Lt Les Jackson, 75 Sqn RAAF, NE of Port Moresby, bailed out, MIA.
7 April 1942 - FPO2c Tan Yukihisa shot down by A-24 defensive gunnery, 8th BS, 3rd BG near Lea, KIA.
11 April 1942 - Flyer1c Tanji Jufuku shot down by FO Pete Masters, 75 Sqn RAAF, near Lea, KIA.
17 April 1942 - FPO2c Sakai Yoshimi crashed in mountains after fight with 75 Sqn RAAF. MIA.
28 April 1942 - FPO3c Maeda Yoshimitsu crashed Otonata Plantation while strafing, POW
30 April 1942 - FPO2c Izumi Hideo shot down by 8th FG P-39s near Lea. KIA.
Balance this loss against the losses suffered by the P-39s. for example, on 26 April 11 P-39s were ditched and lost whilst enroute to Moresby to relieve 24 sqn RAAF. The book, "Attack & Conquer" indicates on page 310 that eleven aircraft were lost that day with the loss of 2 lives. Other sources indicate that only 9 aircraft were lost and the other six Airacobras that did not turn back all making it safely through to Horn Island.
1 May 1942 - FPO2c Arita Yoshisuke shot down by 1/Lt Don McGee, 36th FS, 8th FG over 7 Mile Field, KIA.
2 May 1942 - Flyer1c Kawanishi Haruo shot down near Port Moresby by 1/Lt Don McGee, 36th FS, 8th FG, KIA.
13 May 1942 - FPO3c Honda Toshiaki shot down by 8th FG Airacobras near Lawes Mountain, KIA.
14 May 1942 - FPO1c Oshima Toru collided with 8th FG Airacobra near Port Moresby, KIA
16 May 1942 - FPO2c shot down near Lea by defensive fire while attacking B-25s of 3rd BG, KIA.
17 May 1942 - FPO2c Ito Tsutomu crashed in mountains returning to Lea after hit by ground fire at 12 Mile Drome. POW
17 May 1942 - LT(jg) Yamaguchi Kaoru crashed into mountains after hit by ground fire at 12 Mile Drome, KIA.
25 May 1942 - Flyer1c Watanabe Masao crashed into sea while attacking B-25s of 3rd BG off Salamaua, probably hit by defensive fire. KIA
29 May 1942 - FPO2c Komori Hisao killed by Australian patrol near Iwaia after forced landing following fight with 8th FG Airacobras. KIA
1 June 1942 - WO Miyakaze Gitaro shot down by Cpt Bill Bennett, 35th FBS, 8th FG near Port Moresby, KIA
9 June 1942 - WO Yoshino Satoshi shot down by 2/Lt Curran Jones, 39th FS, 35th FG near Cape Ward Hunt, KIA
9 June 1942 - FPO1c Kikuchi Sakyo shot down by 2/Lt Dick Suehr, 39th FS, 35th FG near Cape Ward Hunt, KIA
Sakai gave a fairly interesting account of this loss
P-39 Airacobras in defence of Australia | The Australian War Memorial
16 June 1942 - Flyer1c Hidaka Takeichiro shot down by 1/LT Francis Royal, 39th FS, 35th FG, near Cape Ward Hunt, KIA
4 July 1942 - Flyer1c Suizu Mitsuo collided with B-26 near Lea, KIA
11 July 1942 - FPO3c Suzuki Matsumi shot down by defensive gunnery from 19th BG B-17s. KIA
20 July 1942 - 4 pilots lost in bad weather between Lea and Rabaul, FPO1c Kobiashi Katsumi, LT(jg) Kurihara Katsumi, FPO2c Miya Unichi, FPO3c Onishi Yoshima MIA
These are the reported losses April - July of the Tainan Group. Credits based on Ruffato's analysis of Allied claims during the period.
Not all the claims are against Tainan. A good number will have been inflicted on the Chitose AG, which had transferred to Rabaul and also to Gasmata and then to Buna (later in the year).

Yes the US and Australians claimed WAAY more than these, but then, so did the Japanese.
Example 9 June 1942 - 22nd BG claimed 11 Zeroes, 35th FG claimed five, and the Japanese claimed four B-26s. Actual losses were 1 B-26 shot down (8 KIA), one force landed at Moresby (repaired/non-operational), one P-39 force landed out of fuel, and two Tainan Zeroes lost with their pilots.

As indicated above, not all the aircraft listed as a loss are the result of P-39s. Some of the aircraft are not for Zeke pilots though most do appear to be in that category. In that period 26April to 29 June the 8FG was more or less bled white from losses, not sure of its complete loss but above 50%, possibly 25-30 a/c? For this effort they shot down or destroyed on the ground (mostly the latter), 7 enemy a/c, according to this list. AWM is slightly higher at 11 enemy a/c. Perhaps this list is allegedly for Zeke losses, and doesn't include other types, though this seems wrong as well , since i believe "other" losses were a lot more than just 3 or four aircraft.

8FG returned from PNG with virtually no serviceable a/c. Some were repairable, but at least 50% losses amounts to around 30 a/c, for the destruction of just 7 "confirmed" so far. That is not a good exchange rate, and certainly does not show the P-39 as competitive to Zeke.

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I'm about half way through General Kenney's Report, commander 5th AF, up to June, '43. He reports various battles stating losses and victories of air battles and ship attacks. He seems to indicate significant victories over the Japanese, especially number of planes downed by heavy bombers, mainly B-17s with little loss. I suspect his numbers came from crew reports which are suspicious. His reports on shipping, however, should be accurate as they sent reconnaissance flights to verify results. He often mentions the P-39 mainly to get new ones to help replace the old, well used ones. I have not found any particular complaint against the P-39 or P-40, contrary to what was stated in America's Hundred Thousand, and seemed to be happy with them. Once he received a bunch of P-39s but found out they had been written up as performance limited, and thus unusable. He wrote for them to be taken back as useless and ask for P-38s. They later corrected the issue with the delivered P-39s and they were used. It should be noted that many of these battles were against Japans best, not being decimated until the battle of Santa Cruz. The P-38 seems to dominate and certainly would be the plane of choice for this theater of operations.