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

DerAdlerIstGelandet · Mar 31, 2019

I thought I walked into the flat earth thread here for a sec...

P-39 Expert · Mar 31, 2019

fubar57 said:
On the plus side, his uncle was there, had first hand experience, knew what he was talking about and wasn't some kind of "expert"

Did not, in any way, mean to disparage the great uncle's brave military service nor his recollection of the past. Just stating my opinion. He, like the P-39/40 was there in '42 and deserves a bigger place in history.

Shortround6 · Mar 31, 2019

P-39 Expert said:
How so? P-40 was slower, climbed slower, had a lower ceiling and about the same range. They both had one centerline external store.

P-40s starting with the F (not sure on Es) had 3 external stores points. In fact I am not sure about some of the earlier ones. The points under the wings were only rated for 100-150lb but they were there. Some of the "strippers" had the underwing points removed but they were added back in first with a 500lb rating and then with a 1000lb per wing rating.

Weight. Soviets removed the usless .30 caliber wing guns.

Hmmm. 1/2 the armament of a SPitfire or Hurricane during the BoB. Yep, must be useless. or Twice the firepower (more than twice) of a Zero or 109 E/F once they had run out of cannon shells. So again, utterly useless. Or let's imagine the fantastic performance of either the Zero or the 109 if those useless guns had been taken out?? granted it is only two guns and ammo but then both of these planes are almost a ton lighter than P-39 to begin with so the percentage weight difference is closer than the 2/4 ratio.

Generally considered more reliable than the P-40 in terms of TBO, daily readiness.

Got any proof of this? and comparing which models? Russians did have a lot of trouble with the first Tomahawks.

The .30s were the biggest problem of the P-39 and were not used on any other production US fighter.

Hmmm, just what the heck were in the wings of the P-40, P-40B and P-40C??

The outer two guns in the Mustang Is were .303s so technically you are correct (that and the Mustang I was a British fighter produced in the US)

The US .30 was used as a defensive gun on thousands of US single engine strike aircraft (mostly Dauntlesses ) and several thousand A-20 attack bombers.

Perhaps those crews should have left the .30s on the ground and depended on the better climb and maneuverability of the planes without them?

Climb and ceiling are greatly increased with only a small reduction in firepower. This is applicable to the early P-39s (D through M). The N climb and ceiling were just fine even with the wing guns/nose armor, but removing them would just make it better.

Just imagine the climb and ceiling of a Spitfire if you took out the four useless .303 guns in the wings

Who needs a MK IX, just take 200-220lbs of guns and ammo out of a MK V and get 6-700fpm more climb and several thousand feet more altitude.
Who needs a P-51, just jam 40-50 gallons of fuel into the wings of MK V Spit instead of the 4 machine guns and Presto, a long range bomber escort.

wuzak · Mar 31, 2019

Shortround6 said:
Got any proof of this? and comparing which models? Russians did have a lot of trouble with the first Tomahawks.

That may have been a problem with the long nose V-1710.

Which is teh only difference which would make the P-40 less reliable than the P-40, as far as I can tell.

Glider · Mar 31, 2019

I have just found a reference to an article written on 1st March 1940 in a highly respected aviation magazine of the period called The Aeroplane about what they thought of the claims made by Bell.
The article dismisses as absurd the various figures published by Bell. In particular a maximum speed of 400mph, a cruising speed of 325mph, an operating altitude of over 36,000ft, a cruising range over 1000 miles on a fully loaded weight of approx. 6,000ib and a wing loading of 28.3 lb per sq ft. This weight the article claimed, is simply impossible with an engine of this size, a particularly long drive shaft and its mounting, the tricycle undercarriage, with the armament specified, with the range and wing loading specified.
The article continued 'The manufacturer must have discovered some wonderful law of nature if they can build an aeroplane that weighs no more than a Hawker Hurricane yet has more horse power, radiators in the wings, about 300lb more fuel, a cannon, a tricycle undercarriage, a long extension shaft and a constant speed airscrew'.
The author then put his finger on the core issue.
'The idea seems to be to get a spectacular top speed for advertising purposes at the expense of everything else. That may be all right in America but when they are exported for war, they will have to be modified to make them lethal.
The summary was equally scathing categorising the Airacobra as 'a thoroughly ill conceived aeroplane, taken in general and in detail'. In a final flourish As a serious fighter the Bell is all wrong. We trust the British Purchasing Commission in the USA will not be hoodwinked into placing an order.

We can take from this that the author wasn't a fan but he got a lot more right than he got wrong. If someone had listened to him and at least put some effort into checking the claims made by Bell a lot of time and effort would have been saved.
When you also consider that the writing style of the time was to be very polite and matter of fact this was really strong language.

Shortround6 · Mar 31, 2019

There was quite a bit of trouble with the Long nose P-40s because they were delivered with a generator much larger than originally specified and the drive system was not up to the load and broke often. replacement drives were supplied but not in enough quantity but the problem was not resolved until both a new generator drive and smaller generators (somewhere between the original specification and the first supplied generators) showed up. This was pretty well sorted out by the time the P-40E and later showed up.

Russian aircraft were also rather difficult to maintain at least in the first year or two. Instead of electrical or hydraulic actuation of flaps/landing gear and other systems they used pneumatics (air pressure) in many of their fighters, which while lightweight, tended to leak (a lot). leading to aircraft parked overnight sitting on their bellies in the morning and other problems.

GrauGeist · Mar 31, 2019

P-39 Expert said:
Your great uncle's P-36 weighed 5700#. His P-39 was a ton heavier and was 50mph faster.

For a closer comparison:
His P-36A weighed 4,550 clean and 5,650 loaded with a speed of 313mph at 8,000 feet.
His P-39D weighed 5,400 clean and 7,500 loaded with a speed of 355 at 10,000 feet.

All those numbers really mean nothing unless you put it into context. He qualified in the P-36 and had quite a few hours logged in it. It was tolerant, nimble and handled very well, which gives a pilot a certain measure of confidence in what they can (and cannot) do with their machine.
Now, he's removed from that comfort zone and put into an entirely different machine that has an entirely different set of rules and he had to discard his P-36 mindset if he was going to live by the Airacobra's rules.
And he didn't like that.

And since we were comparing his P-36 to a P-39, let's see how the P-39 looks compared to a P-38 (I understand that he qualified with the P-38F): Which was 12,250 clean and 15,900 loaded and roughly the same speed at the P-39D at 10,000 feet.

So at nearly 7 tons heavier and roughly the same speed at 10,000 feet, it would *almost* seem that the P-39D was the better deal...

Ivan1GFP · Mar 31, 2019

Hello P-39 Expert,

P-39 Expert said:
Weight. Soviets removed the usless .30 caliber wing guns.

Lets go with what you are thinking for a bit and see where it leads.
The .30 Cal Wing guns weigh 94.9 pounds in total for all 4.
The standard load of ammunition for all 4 guns together is 78 pounds.
Loss of 172.9 pounds.
The Soviets also increased the ammunition load of their .50 cal cowl guns from 200 to 270 rounds.
Ammunition weight goes from 129 pounds to 174 pounds.
Gain of 45 pounds.
for a net loss of 127.9 pounds of armament & ammunition.

So what you are claiming is that 127.9 pounds of weight difference would significantly increase performance?
I don't believe that is a reasonable conclusion.

As for no other US Fighter using the .30 caliber, Shortround6 already commented about early P-40 through P-40C.
Note that the P-36 used them as well.
I do not believe that the US Army would have accepted a 37 mm gun and two synchronized .50 cals as sufficient armament.
As for whether the .30 cal guns were effective, the Japanese and British took down an awful lot of aircraft with that kind of fighter armament.

P-39 Expert said:
And had no effect on normal flight. In order to have any chance of "tumbling" the nose ammo had to be expended, then a vertical climb until near stalling speed, then pull back hard on the stick. To spin or "tumble" a plane had to stall first and the P-39 had excellent stall characteristics.

Your claim is contradicted by pilot reports. Although "Tumbling" was pretty hard to achieve and did require a vertical climb and specific control inputs, a departure and spin was possible in other flight conditions with the CoG too far back. The P-39 had excellent stall characteristics if the CoG was far enough forward but was much less predictable and not very suitable for aerobatics if that was not the case.

P-39 Expert said:
Actually the minimally invasive approach would be for the crew chief at forward bases to remove the underpowered wing guns (and related equipment), the nose armor plate, and move the radios up from the tail cone for balance.

The problem with moving the radio as a field modification is that I don't believe there was enough test equipment out in the field to check for interference with other electrical components such as the engine's ignition system. Radios also tend to be fairly heavy and it would make more sense to have properly engineered brackets supporting them.

- Ivan.

Greg Boeser · Mar 31, 2019

GrauGeist said:
For a closer comparison:
His P-36A weighed 4,550 clean and 5,650 loaded with a speed of 313mph at 8,000 feet.
His P-39D weighed 5,400 clean and 7,500 loaded with a speed of 355 at 10,000 feet.

All those numbers really mean nothing unless you put it into context. He qualified in the P-36 and had quite a few hours logged in it. It was tolerant, nimble and handled very well, which gives a pilot a certain measure of confidence in what they can (and cannot) do with their machine.
Now, he's removed from that comfort zone and put into an entirely different machine that has an entirely different set of rules and he had to discard his P-36 mindset if he was going to live by the Airacobra's rules.
And he didn't like that.

And since we were comparing his P-36 to a P-39, let's see how the P-39 looks compared to a P-38 (I understand that he qualified with the P-38F): Which was 12,250 clean and 15,900 loaded and roughly the same speed at the P-39D at 10,000 feet.

So at nearly 7 tons heavier and roughly the same speed at 10,000 feet, it would *almost* seem that the P-39D was the better deal...

P-36s in Hawaii on 7 Dec 1941 acquitted themselves very well, considering they were unprepared for battle, had to be prepared for combat between strike waves of the Japanese and the pilots had no previous combat experience. In a dogfight near Kaneohe NAS, four P-36s of the 46th PS tangled with nine Zeroes and lost only one plane while claiming two. (Japanese records show no losses, though one plane had to be scrapped on return to the carrier.) Another pair of P-36s caught some B5Ns as they were retiring and Lt Ken Brown flamed two, with only a single .30.

GrauGeist · Mar 31, 2019

Lt. Rasmussen's uniform that morning consisted of purple pajamas and a .45

XBe02Drvr · Apr 1, 2019

Shortround6 said:
Instead of electrical or hydraulic actuation of flaps/landing gear and other systems they used pneumatics (air pressure)

Those Fokkers I worked on at the commuter had pneumatic landing gear, brakes and steering, and were an absolute PITA in our northcountry winters. Fortunately they had bulletproof downlocks, so no unauthorized sitdowns.

XBe02Drvr · Apr 1, 2019

GrauGeist said:
So at nearly 7 tons heavier

HUH? Try 4 tons heavier and twice the horsepower; sure looks like a better deal in my book. And if those turbos stay healthy, altitude's not a problem either. Keep your speed up, boom 'n zoom, hell combat could almost be fun!
Cheers
Wes

XBe02Drvr · Apr 1, 2019

Ivan1GFP said:
I don't believe there was enough test equipment out in the field to check for interference with other electrical components

And you most likely are going to change the length of the antenna feedline. If not tuned properly, standing waves in the feedline can eat up as much as 2/3 of your transmitter power.

GrauGeist · Apr 1, 2019

XBe02Drvr said:
HUH? Try 4 tons heavier and twice the horsepower; sure looks like a better deal in my book. And if those turbos stay healthy, altitude's not a problem either. Keep your speed up, boom 'n zoom, hell combat could almost be fun!
Cheers
Wes

Well, I guess my math is not as great as yours.
P-39D clean: 5,400 pounds
P-38F clean: 12,250 pounds.
That looks to be almost 7 tons difference.

P-39D loaded: 7,500 pounds.
P-38F loaded: 15,900 pounds.
There appears to be about 8 tons difference.

But I suppose counting on fingers can be confusing...

XBe02Drvr · Apr 1, 2019

GrauGeist said:
But I suppose counting on fingers can be confusing..

Well maybe the ROE is changed. I was taught that our quirky Anglo Saxon measuring system considers a ton to be 2000 pounds, but then again, I've seen folks who jump back and forth between Metric and SAE a lot speak of it as if it were 1000 pounds. Maybe it's changed and hasn't penetrated the rock I live under. Any case, I'm too drowsy-eyed to think straight at this hour. I can hear a pillow calling.
Cheers,
Wes

wuzak · Apr 1, 2019

1 short ton (US ton) is 2,000lb.
1 long ton (UK ton) is 2,240lb.
1 metric tonne is 2,204.6lb.

Milosh · Apr 1, 2019

GG, I think you need to recalculate. That is, cut your tonnes by half.

pbehn · Apr 1, 2019

14 pounds = 1 stone
8 stones = 1 hundredweight
20 hundred weight = 1 ton

20 x 8 x 14 = 2,240 lbs

Couldn't be any easier!

wuzak · Apr 1, 2019

Nice and logical.

Not like the stupid
1,000 grams = 1 kilogram
1,000 kilogrames = 1 tonne
1,000 tonnes = 1 kilotonne

etc....

pbehn · Apr 1, 2019

wuzak said:
Nice and logical.

Not like the stupid
1,000 grams = 1 kilogram
1,000 kilogrames = 1 tonne
1,000 tonnes = 1 kilotonne

etc....

11 meters = 36 feet which is why the English always lose a penalty shoot out.

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

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