XP-39 II - The Groundhog Day Thread

[XBe02Drvr]

One point I forgot to mention about the repair work is that one prop blade needed straightened and reconditioned and it is not mentioned in the repair items.

That's the one that sudden-stopped the engine.

 

[SaparotRob]

I read Samauri by Saburo Sakai many years ago. He wrote, IIRC, having spotted a P-39 he came up above and behind it. He followed it noting its cruise speed and the altitude. I think he wrote 200 knots. I can't remember the altitude. He then shot it down. Of course Sakai Saburo was flying a Zero but which model I can't recall.

 

[XBe02Drvr]

I read Samauri by Saburo Sakai many years ago. He wrote, IIRC, having spotted a P-39 he came up above and behind it. He followed it noting its cruise speed and the altitude. I think he wrote 200 knots. I can't remember the altitude. He then shot it down. Of course Sakai Saburo was flying a Zero but which model I can't recall.

I read that years ago also, and given the timing of this event, when IJNAF vs USAAF/RAAF were trading raids back and forth Port Moresby-Lae, likely it was an A6M2.
IIRC, he followed the P39, inspected it closely, marvelled that the pilot seemed to never look in his mirror, then turned off his machine guns, just touched the trigger, and shot it down with four cannon shells, the shortest burst he could fire.

 

[buffnut453]

My whole point is that the weight could be easily reduced AT FORWARD BASES by removing some equipment that wasn't needed. The weight reduction was primarily to increase climb rate and ceiling AT ALL ALTITUDES.

But the simple fact is that the people operating the P-39 didn't do that. Removing unnecessary weight is hardly rocket science, providing it can be done without upsetting the aircraft's CofG. If it was so simple to accomplish and if it would achieve such beneficial results, why wasn't it done? There must be a reason why such an obvious improvement was not implemented.

 

[P-39 Expert]

But the simple fact is that the people operating the P-39 didn't do that. Removing unnecessary weight is hardly rocket science, providing it can be done without upsetting the aircraft's CofG. If it was so simple to accomplish and if it would achieve such beneficial results, why wasn't it done? There must be a reason why such an obvious improvement was not implemented.

Depends on when that happened, but remember in mid '42 the AAF had no combat experience outside of a couple of guys who got off the ground at Pearl Harbor. Nobody really knew what they were doing.

The extra weight and the 110gal drop tank meant the P-39 had trouble getting over 17-18000'. Too bad for the guys that were there, made their lives very difficult.

 

[buffnut453]

Depends on when that happened, but remember in mid '42 the AAF had no combat experience outside of a couple of guys who got off the ground at Pearl Harbor. Nobody really knew what they were doing.

True enough, but the RAAF Buffalo pilots were ripping "unnecessary" weight out of their aircraft after just 3 weeks fighting the Japanese - and none of those Aussies had combat experience prior to 8 Dec 41. From May-August 1942, air combat between USAAF P-39s and Zeros was commonplace. That's 4 months...plenty of time to identify the need for improvement.

Again, I have to ask why the boots on the ground (or in the cockpit) didn't do something to improve the performance if it was as easy and as impactful as you suggest? Is it possible that the theoretical performance improvements you're proposing weren't achievable in practice?

 

[Elmas]

If I remember well, the Zero had a propeller built under an Hamilton Standard license.
So, probably it wasn't too difficult to repair it.
From memory, I may be wrong.

 

[XBe02Drvr]

If I remember well, the Zero had a propeller built under an Hamilton Standard license.
So, probably it wasn't too difficult to repair it.
From memory, I may be wrong.

You're not wrong. I've read that from several sources. I believe the only changes were to substitute metric hardware.

 

[XBe02Drvr]

Again, I have to ask why the boots on the ground (or in the cockpit) didn't do something to improve the performance if it was as easy and as impactful as you suggest? Is it possible that the theoretical performance improvements you're proposing weren't achievable in practice?

I suspect it might have something to do with the local chain of command and how willing they'd be to tolerate "unauthorized" modifications to the aircraft. Feeling vulnerable to criticism due to the less-than-stellar performance of their fighters, they'd be afraid that the poor performance record would get blamed on those modifications. Basic careerthink.
If you look at the P39D carefully, it should become obvious that it wasn't slated to be a stellar tropical fighter. Too much airplane sitting on too little wing with a less than optimum airfoil, and equipped with a low altitude engine whose unorthodox location made the plane prone to squirrelly handling under some combat conditions, just isn't the optimum setup for fighting in the high teens and low twenties in the high temperatures and density altitudes of New Guinea. Even though the performance charts supposedly give it a significant ultimate level flight speed advantage over the Zero, the thin air at those altitudes would likely limit its maneuverability and its acceleration enough to give the Zero a good shot at it before it can pull out of range. There's just so little excess power for climbing, accelerating, or turning.
I don't know how many of you have tried to coax a tired airplane with optimistically rated engines up to its performance chart altitudes and speeds, but I can tell you from frequent experience, it's a frustrating exercise. It wallows like a half flooded lifeboat and acts sluggish like it was approaching a stall, which it is, and steadfastly refuses to get on the step. A Be1900 with both engines in need of hot section overhauls in the first hot days of spring after a winter of eating sand in beta on slippery airport surfaces, is a classic example. You can't make flight planned speeds at flight planned altitudes and are constantly exceeding flight planned fuel burns, necessitating more frequent fueling than the schedule allows. The hurrier you go, the behinder you get.

 

[buffnut453]

I suspect it might have something to do with the local chain of command and how willing they'd be to tolerate "unauthorized" modifications to the aircraft.

Don't disagree. However, during WW2 it's usually the Brits who get painted as the rule-bound bureaucrats while the American free-spirit-thinkers just did what was needed to get the job done. Given the very rough field conditions at Guadalcanal, I have a really hard time believing that stuff-shirtedness would last very long.

Maintenance rules were being broken all the time on Guadalcanal as wrecks were cannibalized for spares. The prospect of greatly improving the performance of the key USAAF fighter in the region by "simply" removing some unnecessary armour plate and the "useless" wing guns strikes me as small beans compared to some of the hybrid airframes that are seen in photos. The book "Lightning Strikes" by Donald A. Davis describes one of the hybrid airframes at Cactus:

"Since there were so few P-400's in service, every cannibalized part could keep another plane flying. The favorite P-400 on the island was a battered craft that had skidded to a halt one day after landing on its belly because its wheels collapsed. It came to a rest with a wing crumpled and the propeller bent, making it an open source for spare parts. However, the need for flyable aircraft was so great that mechanics nursed it back to health. One wing was U.S. Army olive green and the other was British camouflage. Instruments were plugged into gapping holes in the cockpit panel. The three-bladed propeller contained two blades from one wrecked plane and one blade form another; it was balanced by pouring lead in until it spun almost correctly. The aircraft took on a strange personality all its own and would outlast every other plane in the squadron. It was proudly christened The Resurrection."

Given that mish-mash of parts and missing components, the prospect of taking out armour plate and a couple of wing guns really is trivial.

 

[XBe02Drvr]

Given the very rough field conditions at Guadalcanal, I have a really hard time believing that stuff-shirtedness would last very long.

Guadalcanal was a "generation" of war experience later and an even more desperate situation with a longer and more tenuous supply chain than early days in New Guinea, with the IJNAF by day and Tokyo Express by night. And don't forget "Maytag Charlie"!
And the P400s with their non US standard setups were in an even more desperate spares situation. Any tendency toward formality would be long gone by then, especially with Gen Vandegrift around.

Instruments were plugged into gapping holes in the cockpit panel.

We used to have an Albany based competitor on the SLK-ALB-LGA run who ran ancient beatup Be99s that fit the above description and would have made "The Resurrection" look like a virgin. Great source of pilot recruits, as our company actually paid a living wage, and these guys came to us deep in debt, but well experienced in emergency procedures. Despite being headquartered right next to the FAA FSDO, who received constant complaints about them, their owner's political clout rendered them untouchable until a change of administration in NY state government and the end of the Reagan administration deprived him of his influential connections. Then they lost their certificate.

 

[SaparotRob]

Guadalcanal was a "generation" of war experience later and an even more desperate situation with a longer and more tenuous supply chain than early days in New Guinea, with the IJNAF by day and Tokyo Express by night. And don't forget "Maytag Charlie"!
And the P400s with their non US standard setups were in an even more desperate spares situation. Any tendency toward formality would be long gone by then, especially with Gen Vandegrift around.


We used to have an Albany based competitor on the SLK-ALB-LGA run who ran ancient beatup Be99s that fit the above description and would have made "The Resurrection" look like a virgin. Great source of pilot recruits, as our company actually paid a living wage, and these guys came to us deep in debt, but well experienced in emergency procedures. Despite being headquartered right next to the FAA FSDO, who received constant complaints about them, their owner's political clout rendered them untouchable until a change of administration in NY state government and the end of the Reagan administration deprived him of his influential connections. Then they lost their certificate.

That's quite an item for job application. "Experienced in aircraft catastrophes because I worked for a corrupt air carrier."

 

[XBe02Drvr]

That's quite an item for job application. "Experienced in aircraft catastrophes because I worked for a corrupt air carrier."

We stole quite a few pilots from ragtag marginal commuter carriers. It was the boomtown expansion of the regional airline industry in the 1980s, stepping in to serve the smaller places the majors were allowed to abandon under deregulation. It attracted all kinds of slick operators trying to build an empire on other people's money, often with limited understanding of the nuts and bolts of aviation business. It was the Reagan era, entrepreneurship was king, the rules were often more winked at then obeyed, and the carnage was horrendous by today's standards. Shoddy operators like Frank Lorenzo, Carl Icahn, and Allyn Caruso were the darlings of the entrepreneur worshipping set as they amassed fortunes and power off the backs of their creditors, their employees, and the diminished safety of the flying public.
OTOH, they gave pilot jobs to unlikely specimens of airline pilotage like me, who wouldn't have a snowball's chance you know where of getting hired by a major airline. (Not military trained, too tall, too skinny, too unattractive, wearing THICK glasses, history of eye disease and other chronic conditions, and a little shy on multi engine time.) I just didn't fit the desired profile. Oddly enough a lot of the "less desirables" who got hired by commuter airlines that survived the consolidation wars and were absorbed into the major airline networks wound up retiring as senior captains at American or United or Delta, including some of the folks I flew with at Brockway, who went over to Business Express after we went Chapter 11, then 7, thanks to Carl Icahn.

 

[XBe02Drvr]

during WW2 it's usually the Brits who get painted as the rule-bound bureaucrats while the American free-spirit-thinkers just did what was needed to get the job done.

And where was USAAF's SW Pacific base of operations, command and control? In RAAF territory with plenty of RAF bureaucrats right at hand. "When in Rome, do as...etc, etc."

 

[buffnut453]

And where was USAAF's SW Pacific base of operations, command and control? In RAAF territory with plenty of RAF bureaucrats right at hand. "When in Rome, do as...etc, etc."

Oh come off it. Are you really suggesting that it's the Brit's fault that Americans didn't take steps to improve their own aircraft? Really??? That's too much. Has ANY American listened to a Brit since 1775?

 

[Ivan1GFP]

That's the one that sudden-stopped the engine.

Hello XBe02Drvr,

You might be right, but I suspect that more likely it was the one that ended up stuck in the mud for a couple months when the plane flipped over. That blade sticks out pretty far and the flip was violent enough to destroy the canopy and buckle the fuselage at the cockpit. I still can't quite figure out how exactly the plane wiped off both main gear, scraped up the belly and flipped without that much damage to the underside of the cowl or the other two prop blades.

- Ivan.

 

[buffnut453]

Guadalcanal was a "generation" of war experience later and an even more desperate situation with a longer and more tenuous supply chain than early days in New Guinea, with the IJNAF by day and Tokyo Express by night.

First combat for the 39th took place on 30 Apr 1942 so hardly a 'generation' of war experience. Regardless, even if we include the experience of getting P-39s operational in New Guinea as 'war experience' it still doesn't change my question, in fact it makes it even more relevant.

Inexperienced Aussies operating in Singapore under RAF command could strip weight out of their Buffalos, including changing 50cals for 303s in the wings, after just 3 weeks of combat. Why, then, didn't any USAAF units do a similar thing with their P-39s and P-400s?

The "they were inexperienced" excuse doesn't make sense, nor does it tally with the innovation demonstrated at Guadalcanal, first erecting P-400s without manuals and then keeping them flying despite the incredibly long and at-risk supply chain.

Of note, "Buzz" Wagner (CO of the 39th) recommended around 8 changes to the P-39 including ADDING armour to protect the engine, and improving reliability of the wing-mounted 30 cals. Again, if the "useless" wing guns weren't reliable, why not just take them out?

It seems to me that someone would at least TRY to reduce the weight of the under-performing P-39s if they thought it would do any good. One logical conclusion is that they didn't think it would help much.

I'm open to other suggestions but they need to be realistic and relevant.

 

[P-39 Expert]

First combat for the 39th took place on 30 Apr 1942 so hardly a 'generation' of war experience. Regardless, even if we include the experience of getting P-39s operational in New Guinea as 'war experience' it still doesn't change my question, in fact it makes it even more relevant.

Inexperienced Aussies operating in Singapore under RAF command could strip weight out of their Buffalos, including changing 50cals for 303s in the wings, after just 3 weeks of combat. Why, then, didn't any USAAF units do a similar thing with their P-39s and P-400s?

The "they were inexperienced" excuse doesn't make sense, nor does it tally with the innovation demonstrated at Guadalcanal, first erecting P-400s without manuals and then keeping them flying despite the incredibly long and at-risk supply chain.

Of note, "Buzz" Wagner (CO of the 39th) recommended around 8 changes to the P-39 including ADDING armour to protect the engine, and improving reliability of the wing-mounted 30 cals. Again, if the "useless" wing guns weren't reliable, why not just take them out?

It seems to me that someone would at least TRY to reduce the weight of the under-performing P-39s if they thought it would do any good. One logical conclusion is that they didn't think it would help much.

I'm open to other suggestions but they need to be realistic and relevant.

Armor behind the engine was included in the armor totals. Thinking it wouldn't help much and not knowing how much it would help are two different things.

 

[buffnut453]

Armor behind the engine was included in the armor totals. Thinking it wouldn't help much and not knowing how much it would help are two different things.

So you do what every good to tinkerer does and try an experiment. That's what the Aussies did. They took one Buffalo, stripped out the excess weight, replaced the wing 50 cals with 30 cals, replaced the 50 cal fairing bumps with smooth sheet, and then they flew a trial against a standard Buffalo. The results were good enough that, reportedly, they made the change to all the squadron's aircraft (although none of the other Buffalo squadron's followed suit).

None of the above was challenging and it gave a good enough demonstration of the performance improvement. You still need to find a worthwhile excuse for why at least one USAAF P-39/400 squadron didn't attempt something similar.

As to the armour for the engine, I never said there wasn't any. I said Wagner asked for more of it.

 

[buffnut453]

While I'm on a roll here, also remember a few weeks ago the discussion of how Americans were so much better equipped for WW2 because they all had Model Ts and knew how to tinker with engines? Now, apparently, it was beyond the ken of those same Americans to realise that removing unnecessary weight from an aircraft would improve its performance...and that they couldn't work out how to demonstrate those benefits objectively.

C'mon fellas...pick one side of an argument and stick with it, please.