Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained) (1 Viewer)

33k in the air said:

The document Development of the Long-Range Escort Fighter on pages 70, 93, and 119 has illustrations showing the way the escorts were positioned and flew.


ETA: There is also this from Target Berlin regarding the 6 March 1944 mission (p.14):

When fully assembled, the bomber stream for a large attack could be more than 90 miles long. Because they cruised somewhat faster than bombers and had to zig-zag to maintain station on them, individual fighter groups could not cover bombers for much more than 30 minutes at a time before fuel began to run low and they had to break away. As a result only a small proportion of the available escort fighters would be in position to cover bombers at any one time. On 6 March only rarely would there be more than 150 escorts in position; if these were distributed evenly along the length of the bomber stream there would be an average of only three fighters for every two miles of airspace. Such a split force would obviously have been ineffectual and easily overwhelmed by the enemy; so it was usual to position about a third of the fighters near the head of the bomber stream --- that part most vulnerable to head-on attack --- and distribute the remaining fighters in 8-aircraft units along the length of the stream. It was inevitable, therefore, that from time to time some combat wings would have no fighters covering them.

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USAF Study 136 is probably the best source for Development and Tactics for evolving Fighter Escort as well as rich insight to the politics of AAC/AAF development of airpower in the 30's and early 40's.

As to Target Berlin narrative, Jeff glossed over the existing tactics as well as the issues confronted by the 8th AF Mission Planners. Consider that the March 6 Berlin attack was perhaps the simplest, namely 3 intact Bomb Divisions flying in-trail, relatively easy for individual fighter groups to find and escort their assigned boxes (within BD section of the long trail). You also get the impression that the LR escort FGs split into autonomous sections to more evenly distribute along the bomber stream. Nope - a squadron tasked to cover say, a box of 50 bombers would split into two sections to cover each other wile 'essing'. Only in very rare situations would sections be dispersed. The 56th FG Zemke Fan actually broke into flights and damn near lost Gp CO Zemke as a result.


NOTE: Summer 1943 brought distinctive Tail Markings (i.e "Triangle A" for 91st BG, "Square D for 100th Bomb Group) to make it easier (possible) to identify a specific Bomb Group - both for bomber crews and fighter squadrons searching for their flock.

There was no 'even distribution - ever. Particularly in January through April, the number of LR escort fighter groups (P-38J/P-51B) were combined (3Jan, 4 into Big Week, 7 for March 6-8 Berlin missions, 8 through mid April)

The 'math' was One FG per BD for Target escort until end of Big Week, Two FG through late April. If only one to three target areas were attacked. If the strike as complex with up to five task forces striking dispersed target areas, the available FG escort per Task Force was back to One.

Each BD was comprised of Multiple Combat Wings - each CBW with multiple BG, each with prominent Tail ID.

The lowest common denominators was the 'Box' usually several per BD and composed with two BG - one complete and one partial (i.e. The partial BG was usually one squadron from another group attached to the complete 4 squadron BG to get the box up to ~ 50 bombers. The reason was to ensure maximum compactness to shorten the length of the Task Force to get better concentration of bombs and make it easier to b 'found' and escorted.

Squadrons broke into sections for weave, in order to cover each other and to disperse to each side of the formation. Early in LR escort experience cycle, the squadrons took position and High Front, Center and Rear. Later High Center, sweep front and 'roving' side escort along the shoulder of the bomber formation believed most vulnerable to large scale attacks.

What is the point? For Berlin, the task was relatively simple - Six total LR escort covered 90 miles of airspace, with one of the six (4th) splitting into one and two squadrons to sweep in front as well as provide high cover over the leading three boxes of the 1st BD/1st TF. The 354th provided three squadron coverage to 3rd BD/2nd TF. The three P-38 FGs provided rear box coverage to 2nd TF and Front/Rear coverage to 2nd BD/3rd TF.

LW put up 460 day fighters, Approximately 60% engaged from east of Frankfort - all along the bomber stream but most against the 1st and 2nd TF.

Several of the 11 P-47 FGs providing Penetration escort were key to the 36-7-12 VC total. Of the LR escort the 3 P-38 FGs scored 3-0-1 while the 3 Mustang Groups scored 43-1-20

There are so many jewels buried in this thread. Thanks drgondog.

I admit that I missed the bit where the P39 was considered. All sorts of options were in the paper including the 'fighter' B17 but no mention of the P39. Wonder Why?

Glider said:

I admit that I missed the bit where the P39 was considered. All sorts of options were in the paper including the 'fighter' B17 but no mention of the P39. Wonder Why?

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The YB-40 was a better fighter?

SaparotRob said:

The YB-40 was a better fighter?

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Yeah, it didn't have nose armor...

drgondog said:

USAF Study 136 is probably the best source for Development and Tactics for evolving Fighter Escort as well as rich insight to the politics of AAC/AAF development of airpower in the 30's and early 40's.

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Is that available online?

drgondog said:

As to Target Berlin narrative, Jeff glossed over the existing tactics as well as the issues confronted by the 8th AF Mission Planners. Consider that the March 6 Berlin attack was perhaps the simplest, namely 3 intact Bomb Divisions flying in-trail, relatively easy for individual fighter groups to find and escort their assigned boxes (within BD section of the long trail).

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To be fair though the book isn't about escort tactics. I wouldn't expect the kind of detail on the subject such as you related.

33k in the air said:

Is that available online?

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Lol - yes you posted the link above.

drgondog said:

Lol - yes you posted the link above.

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I think we're all seeing double from this thread by now.

33k in the air said:

The document Development of the Long-Range Escort Fighter on pages 70, 93, and 119 has illustrations showing the way the escorts were positioned and flew.


ETA: There is also this from Target Berlin regarding the 6 March 1944 mission (p.14):

When fully assembled, the bomber stream for a large attack could be more than 90 miles long. Because they cruised somewhat faster than bombers and had to zig-zag to maintain station on them, individual fighter groups could not cover bombers for much more than 30 minutes at a time before fuel began to run low and they had to break away. As a result only a small proportion of the available escort fighters would be in position to cover bombers at any one time. On 6 March only rarely would there be more than 150 escorts in position; if these were distributed evenly along the length of the bomber stream there would be an average of only three fighters for every two miles of airspace. Such a split force would obviously have been ineffectual and easily overwhelmed by the enemy; so it was usual to position about a third of the fighters near the head of the bomber stream --- that part most vulnerable to head-on attack --- and distribute the remaining fighters in 8-aircraft units along the length of the stream. It was inevitable, therefore, that from time to time some combat wings would have no fighters covering them.

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Thank you for the link and the excerpt. I've got family here now, so will fully read your link in the next day or two [ETA: I just saw it runs 333 pages. It might be more than a couple of days!].

But this is what I love about this forum, it's such a wealth of information. Much appreciated, brotha.

Milosh said:

Iirc there was close escort and extended escort. The extend (not sure this is the correct word) flew some distance out in front of the bomber formation. The close escort, one group on each side and one trailing the bombers.

edit: this might have come one of the Mighty Eighth books

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I remember reading something about it in Gerald Astor's oral history, The Mighty Eighth, but that was about three centuries ago, lol. It got confuzzled in my head.

Thank you both for the answers!

The conflict constantly evolved as most do, I found this on the Quora web site posted by Steven Rusling.

First, head on attacks. These were very difficult for anything but an experienced pilot. There was certainly no five second firing opportunity or use of rockets or aerial mortars (which were 'stand off' weapons to be fired from outside the range of the bombers' defences).

Here's an account of the problems associated with head on attacks from a man who flew them in real life, rather than on a computer game, and an explanation of why the tactic was attempted at all.

Fw. Fritz Ungar flew with JG 54 and JG 26, from August 1943 until the end of the war, and was credited with three bombers destroyed.

"During an attack from behind, we were under defensive fire from the bombers too long, and at least three machine gun positions fired at us from each aircraft. In addition, the escorting fighters had the task of keeping us away from the bombers. We had no option but to attack from head on. Everything went very quick in this tactic. Every second brought us 220m closer together. Of course we didn't want to collide, but pull away over the bomber. For this pulling up and over the bomber, one needed almost the whole last two seconds (=400m). Our guns were adjusted for 400m. Therefore we had two options: to fire too early, already at a distance of 600m or 500m, or to pull up half a second later. A very dangerous business. We didn't have one second to fire our guns. It is incredible when one thinks of all the efforts we had to make for just one second. One thing was absolutely necessary: aim very precisely for this short moment."

The fighters did not go at the bombers as fast as possible either. They would manoeuvre for position, following initially their controller's commentary and then the orders of the various commanders in the air. They would seek an opportunity to attack the bombers whilst evading the escorts. Later in the war, Luftwaffe 'Jagdflieger' became very wary of escort fighters and were sometimes reluctant to attack well escorted formations. The bombers' defensive fire was certainly a factor, but there was never any hesitation about attacking unescorted bombers, it was the escort fighters that were the real problem.

Here is another Luftwaffe pilot, Oblt. Otto Stammberger, a Staffelkapitan with 4./JG 26 describing the defensive fire from the bombers.

"Even under these relatively favourable circumstances [When an unescorted formation was intercepted] it was sheer murder to attack the American combat boxes from the rear, which we sometimes did in an effort to get more time to fire. This left us exposed to the defensive fire of the bombers for a longer time too. At a distance of some 1500m the US Viermots opened fire from all barrels. A bomber formation usually consisted of 20 machines, which flew in rows of four planes and were sideways echeloned, and in which these rows of four bombers were stacked on top of each other with row four and five flying in the middle. We normally opened fire at a distance of 300m and tried to close in to 30m or 40m. During all this time our fighters were subjected to the defensive fire of at least eight machine guns per bomber, which, with a group of 20 bombers, meant the concentrated fire of 160 machine guns…Opening fire from behind, at 300m distance, and taking us 5 or 6 seconds to overtake the bombers, these attacks were indescribable in their sheer physical and mental stress…We therefore changed tactics and started attacking from head on, which called for incredible dexterity, a good aim and nerves of steel until the last second."

Glider said:

admit that I missed the bit where the P39 was considered. All sorts of options were in the paper including the 'fighter' B17 but no mention of the P39. Wonder Why?

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What was this thread about again?

SaparotRob said:

The YB-40 was a better fighter?

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Did the Russians love it?

pbehn said:

The fighters did not go at the bombers as fast as possible either. They would manoeuvre for position, following initially their controller's commentary and then the orders of the various commanders in the air. They would seek an opportunity to attack the bombers whilst evading the escorts. Later in the war, Luftwaffe 'Jagdflieger' became very wary of escort fighters and were sometimes reluctant to attack well escorted formations. The bombers' defensive fire was certainly a factor, but there was never any hesitation about attacking unescorted bombers, it was the escort fighters that were the real problem.

Here is another Luftwaffe pilot, Oblt. Otto Stammberger, a Staffelkapitan with 4./JG 26 describing the defensive fire from the bombers.

"Even under these relatively favourable circumstances [When an unescorted formation was intercepted] it was sheer murder to attack the American combat boxes from the rear, which we sometimes did in an effort to get more time to fire. This left us exposed to the defensive fire of the bombers for a longer time too. At a distance of some 1500m the US Viermots opened fire from all barrels. A bomber formation usually consisted of 20 machines, which flew in rows of four planes and were sideways echeloned, and in which these rows of four bombers were stacked on top of each other with row four and five flying in the middle. We normally opened fire at a distance of 300m and tried to close in to 30m or 40m. During all this time our fighters were subjected to the defensive fire of at least eight machine guns per bomber, which, with a group of 20 bombers, meant the concentrated fire of 160 machine guns…Opening fire from behind, at 300m distance, and taking us 5 or 6 seconds to overtake the bombers, these attacks were indescribable in their sheer physical and mental stress…We therefore changed tactics and started attacking from head on, which called for incredible dexterity, a good aim and nerves of steel until the last second."

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Egon Meyer was generally credited with developing and leading the first 'head on attack' in November 1942. Adolph Galland improved on it by instructing the attacking Fw 190 pilots to Not Split Ess - but to pass through the formation to recover, turn, pace and regain Rotte/Stafel size force to repeat. His comments (valid) were to the effect that the dive away required too much fuel and time to rejoin the B-17 formations.

While successful, the tactic required great skill by the leader as well as the entire force to hold steady for makeable shots to the frontal area of the target bomber.

GrauGeist said:

Then you proceed to ignore the peer reviewed, manufacturer's, military's and actual pilot's information and proceed to post flawed, skewed, cherry-picked or imaginary information/data over and over and over and over and over and over and over and over and over and over and over...

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Thank you for making me realize how long it was since last I listened to this:


Groundhog threads do have many uses...

drgondog said:

Egon Meyer was generally credited with developing and leading the first 'head on attack' in November 1942. Adolph Galland improved on it by instructing the attacking Fw 190 pilots to Not Split Ess - but to pass through the formation to recover, turn, pace and regain Rotte/Stafel size force to repeat. His comments (valid) were to the effect that the dive away required too much fuel and time to rejoin the B-17 formations.

While successful, the tactic required great skill by the leader as well as the entire force to hold steady for makeable shots to the frontal area of the target bomber.

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Agreed Bill, it wasnt my post I found it somewhere else, I thought it interesting because it discusses how tactics changed from the people involved.

Some pilots and squadrons favoured head on attacks in the BoB. Some have equated the RAF "Big Wing" idea to the massed "company front" attacks of the LW. They had the same basic idea to deliver a massive blow with a combined simultaneous attack, and the solution for US air forces was what Galland wanted to do in the BoB, to sweep ahead of the bombers to catch LW fighters climbing, forming up and attacking.

drgondog said:

Lol - yes you posted the link above.

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LOL sorry, I misread your post and thought you were referring to a different document. D'Oh!

My bomber escort calculations are correct.

Read the directions in the pilot's manual and use the Flight information Instruction Chart, everything you need is in that chart. You don't need any other reference. There were four segments to an escort mission, takeoff and climb (20gal per the chart), combat for 20min, landing reserve 20min, with the rest of the fuel used for cruising.

Reserve for combat isn't based on 147gph, combat would take place at 25000' or so. Fuel burn at 25000' was 62gph at 2600rpm (normal power). Combat power was 3000rpm, I'm estimating 72gph so 20min would be 24gal. Plane would still climb at almost 2000fpm at 25000', phenomenal performance when compared to other fighter planes in 1943.

Early N models had the normal 120gal internal fuel, kits were available to convert 87 gallon models back to 120gal. 110gal drop tanks were common on 8th AF fighter bases during that period. 110gal tanks were also used extensively by P-39s in the Pacific.

20 minute reserve for landing is what I have always heard. If you want to use 30gal reserve fine, use that. Navy used a 60 minute reserve, but their pilots had to find an aircraft carrier to land on. In any case a landing reserve was needed in case the base was closed by weather or the pilot was lost.

Escort pilots were strongly encouraged to bring the drop tank back, they cost money like everything else. There were 110gal paper tanks also, but they were only good for one mission. If combat came before the fuel was exhausted in the drop tank, they the mission was abbreviated, just like any fighter that carried a drop tank.

The 20 gallons you are using is takeoff and climb to 5,000 feet, Expert. Read the chart, for crying out loud. Also, that test was NOT a stock P-39N. It was flown at 7,274 pounds. The pilot's manual for a P-39N, with the ammunition on board and no extra drop tank comes in at 7,517 pounds (again, with ammunition and without drop tank). Without the drop tank, the range is utterly useless.

A stock P-39N has a 1,200 hp engine with takeoff at 50.5 " MAP and 1,125 hp WER at 44.5" MAP. The report is a test using 59.8" MAP and 1,420 hp that was not released for squadron use. So, you are again cherry picking at an advanced level.

Say you were actually flying a stock P-39N, and you take off and climb to 5,000 feet with your 20 gallons of fuel and you allow for 10 minutes combat at 135 gallons per hour. That leaves you just 44.5. minutes of cruising at 255 mph at 6,000 feet (I let you magically climb 1,000 feet with no fuel burn). Counting the distance traveled in climb and the 44.5 minutes at 255 mph, your range is just under 100 miles ... not really of much use. At 7,500 pounds and 25,000 feet, a stock P-39N can climb at about 1,250 feet per minute assuming it is at Emergency Power. It could climb at 1,100 fpm if at normal power.

For comparison, a Spitfire Mk V in 1941, a year earlier than your high horsepower P-39 test you are looking at just in case you aren't looking at dates, was climbing at 1,940 fpm at 23,000 feet. And it didn't have any issues with C of G, nose armor, or car doors that needed to be opened to bail out. Plus it was in widespread use by the British, something the P-39N wasn't.

But, I'm sure you would KNOW this if you read the test report and also looked at the manual for the service airplanes with an unbiased eye.

You certainly do like the airplane. Perhaps not without some justification. It wasn't a BAD fighter until it ran across an enemy fighter at an altitude above 12,000 feet or so that was closer to home than about 170 miles. Then it was less than wonderful. Of course, you really wouldn't be running into an enemy fighter farther away from home than about 170 miles anyway or you'd run out of fuel getting home. A Spitfire Mk Vb was considered a short ranged and it could travel over 1,100 miles, making for a combat range of half that, or about 550 miles. You'd need more than twice the P-39's range just to be considered a "short range fighter!" But, hey, you could intercept low-altitude enemies over London as long as you kept a close eye on the fuel gauge. A great point-defense or short-range attack, low-altitude fighter, and that is a niche that the Russian exploited.

P-39 Expert said:

Using a P-39N with 120gal internal and 110gal drop tank (230gal) deduct 20gal for takeoff and climb,

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That gets you to 5000ft, switch to drop tank is probably a bit earlier.

P-39 Expert said:

25gal for 20min combat at 25000' and

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actually about 40 gallons would be a better estimate.

P-39 Expert said:

10gal for 20min landing reserve at 5000'.

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Going to loose a lot planes looking for airfields, an extra 5 gallons might be to your advantage.

P-39 Expert said:

The remaining 175gal (cruise) is divided by 62gallons per hour giving a flight time of 2.8hrs multiplied by 276mphTAS = 772mi.

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Doesn't work that way unless you want an lot of planes running out of gas.
Drop tank does not count for combat (especially a 110 gallon tank) and does not count for return flight.
You have 60 gallons or less internal fuel for the trip back.
Every other escort fighter was figured as internal fuel minus take-off allowance, minus reserve for "landing/finding field" and combat allowance.
only reason the P-39 looks good for fuel consumption is because it isn't making enough power.

P-39 Expert said:

Reserve for combat isn't based on 147gph, combat would take place at 25000' or so. Fuel burn at 25000' was 62gph at 2600rpm (normal power). Combat power was 3000rpm, I'm estimating 72gph so 20min would be 24gal. Plane would still climb at almost 2000fpm at 25000', phenomenal performance when compared to other fighter planes in 1943.

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You estimate wrong. You have been told this before.

going from 2600rpm to 3000rpm is a about a 15% increase in RPM. Since internal friction goes up with the square of the speed (RPM) that is a 33% increase in power lost to internal friction. Guess what? the power to turn the supercharger impeller goes up with the square of the speed, another 33% increase in power required just to turn 3000rpm.
Where does this power come from?
Pixie dust?
Unicorn Poop?
Satanic rituals?
Groundhog mystical incantations?

Try more fuel burned in the cylinders to get the power at the Propshaft measured in lbs/hp/hr.

A much closer estimate would be the amount of fuel needed at 15,500ft for military power divided by the fuel burned for that power,(1125hp divided by 138 gallons equals 8.15 hp per hour per gallon). then find the power at 25,000ft and divide by 8.15. (770 hp divided by 8.15 equals 94.47 gallons and hour) or 31.17 gallons for 20 minutes.
However that is ONLY if the P-39 can remain at 25,000ft. If it is forced to trade altitude for speed at any point and descends to 20,000ft the with the engine still doing 3000rpm and the throttle still wide open it will make about 910 hp and the fuel burn will go to 111.65 gallons per hour (or 1.86 gallons per minute.)

The phenomenal performance actually looks pretty crappy compared to P-38G or a Spitfire VIII or even a Spitfire IX.

Or even a MK IX Spit with a 30 imp gallon tank still attached.

Sorry, 370mph or so at 25,000ft just isn't good enough.

P-39 Expert said:

Read the directions in the pilot's manual and use the Flight information Instruction Chart, everything you need is in that chart. You don't need any other reference. There were four segments to an escort mission, takeoff and climb (20gal per the chart), combat for 20min, landing reserve 20min, with the rest of the fuel used for cruising.

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Read the Take-Off, Climb, and Landing Chart on page 26.

Climb Data
8,000 lbs (combat): sea level to 25,000 feet: 13.9 minutes; 39.7 gallons fuel consumed from sea level
7,500 lbs (combat): sea level to 25,000 feet: 10.8 minutes; 35.3 gallons fuel consumed from sea level
7,100 lbs (combat): sea level to 25,000 feet: 9.9 minutes, 34.0 gallons fuel consumed from sea level

Note that the above fuel consumption figures include warm-up and take-off allowance.

P-39 Expert said:

Escort pilots were strongly encouraged to bring the drop tank back, they cost money like everything else. There were 110gal paper tanks also, but they were only good for one mission. If combat came before the fuel was exhausted in the drop tank, they the mission was abbreviated, just like any fighter that carried a drop tank.

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If you get into a fight, the drop tanks are immediately released. Carrying them into combat means extra drag (and weight) on the aircraft, reducing performance. There's also the danger of fire if the drop tank is not self-sealing.

The 108-gallon paper tank was widely used in the ETO because these were cheap to manufacture and used material which was of no benefit to the enemy if dropped over enemy territory. They were also quite a bit lighter than metal tanks. The metal 110-gallon tank was far less common. (There were actually two 110-gallon metal drop tanks: one cylindrical and one tear-drop shaped which came into use later. It had better aerodynamics than the cylindrical version.)

I have seen a photo of a P-39 sporting the 150-gallon 'flat' drop tank created for the P-47. I don't know if the P-39 ever carried that particular type of tank into combat.

Again, the combat radius is determined by how far the aircraft can go on internal fuel after deducting the fuel set aside for combat, reserve fuel, warm-up, take-off, and initial climb.

120 gallons won't take you far after the appropriate deductions are made.