p-80 V Me 262

[kool kitty89]

I didn't say it was accurate of reality I just meant it was another interesting comparison. Look what the purpose of website is. (it's about the Blackhawks comic series) It's been noted several times on the "WWII In Color" forum.
see: The First American Jet (1942) - WW2inColor Talk

Sorry though, I should have been more clear on the purpose of the post...

Although, while the written statements aren't very correct, the chart has the same figures as FlyboyJ's one on page 1.

 

[Civettone]

In reality the P-80 would have had to face the Me 262s with the Jumo 004D engines which were both more reliable as powerful. I think that would have definitely given it the edge over the P-80.

Kris

 

[kool kitty89]

The 004D also had better throtle-up characteristics, longer service life, higher rev limit, and lower fuel fuel cnsumption than the 004B.

The P-80 still has the weapon advantage (unless the Me 262 used an alternative armament), lighter controls due to hydrolic booting, air-breaks, longer range, higher ceiling, and a pressurized cockpit (though the Me 262 was designed to accomedate pressurization, though this was never used in practice). The P-80A had lower wing-loading, though later models were quite higher due to increased thrust allowing higher maximum loads. The P-80A had a better thrust/weight with a normal (empty wing racks) load, normal normal range. (3850 lbf with 11700 lb load 14,000 lb was the max) The info on one of FlyboyJ's posts on page 1 said "Empty weight: 3,800 kg (8,400 lb)
Loaded weight: 7,130 kg (15,720 lb)
Max takeoff weight: 6,400 kg (14,100 lb)" I've seen this elsewhere too, this hence the confusion.

The P-80A also seems to have a faster initial climb and avrage climb to 20,000 ft. Though, I've seen conflicting data on this.

Actually, since the wing area of the P-80 is 237.6 square ft compared to the 262's 233.5 and the max weights of 14,000 lbs and 14,110 lbs the wing loading was almost the same. (I've also seen 15,720 lbs for the Max of the 262, but this is passes the max-takeoff, so I'm not sure, maby max load the airframe would allow with sufficient thrust?)

The Me-262 had the automatic LE slats though and a higher mach figure (though with no airbrakes, terminal dive was difficult to recover from)

On the Wright Field fly-off comparison test, I've never seen a resourse to site it, and even a consistant conclusion. (some say it was supressed due to the 262's superiority, others say that the 262's only advantage was dive speed, still others say that the 262 was superior in some respects but much detail is left out) The only conclusive comparison I've ever seen was a quote from Chuck Yeager saying that,having flown both planes, they were pretty much equal in all apreaciable performance aspects.

I'd really like to see the official version of that test.

Also I've read: "I've seen (In the book Me-262, Smith and Creek, Volume 4) a summary of a direct comparison test done after the war that suggested the overall superiority of the Me-262. But it's important to note that that comparsion was between a stripped recon verson of the Me-262 and the XP-80 (which was dimensionally smaller and had 1,000 lbs less thrust than the P-80A). This was the only test that I know of where both planes were present at the same place and time.

However, I know of at least 4 other comparison studies that were done by the USAAF between the P-80A and the Me-262. Results of two of those tests are unknown to me. The others concluded the general superiority of the P-80A. One pilot in one of the latter tests stated "The Me-262 may be the best jet fighter in service, but the P-80 is the best jet fighter in the world." I guess he meant combat service." See: Messerschmitt Me 262. - Page 10 - WW2inColor Talk

So this skews the comparison even more. Especially he one using the XP-80 (Lulu Belle/Green Hornet), it was a completly different airframe than the XP-80A (gray ghost and silver ghost) and the resulting production craft, with coresponding different characteristics. (the XP-80 was Lockheed's model L-140, the XP-80A was the L-141) The XP-80 was fairly underpowered (using the 2,400 lbf Halford H.1) and at least 50mph slower.

I've also never seen a difinitive figure on the P-80's critical mach number. I know the 262 lost control at .86 mach and I don't think the Meteor (including F.8 ) could go past .82 mach, but what about the P-80? (straight wings doesn't always mean lower mach number, there were several straight-winged craft without mach limits, the XS-1 was straight-winged as was the Avro CF-100 which could dive through mach-1) I wouldn't have been too surprised if the P-84 could break the sound barrier if it had low-profile wings (the wings being the main limiting factor, made thick intentionally to extend range; quite thicker than the P-80's, in fact this dropped the crit-mach number to below the P-80's IIRC) and, of course, the tailplane would need to be trimmable (variable incedence) to mantain controll.

To truely compare maneuverabillity, you'd need the maximum G load figures which I haven't seen either. (Though I've heard that, while the boosted alerons remained light at high speeds, the elevator became quite heavy, though this depended on the COG as it got lighter the farther back the COG was.)

One final note Soren, from the details I've seen, the P-80 should generally more maneuverable, though I'd expect more drag from the wings durring maneuvering, but the P-80 also had a narrower fusalage and much narrower nose (though both are a bit taller than the 262's triangular/shark-like nose) which means less drag area in the turning access. Though it the Me 262 had better flow characteristics the actual drag would be less, despite the higher area.

 

[delcyros]

Why all this argument, I cannot understand.

Both planes are excellent jet´s for their era. Turn rates- and diamters in the horizontal are only important for pilot´s flying ww1 tactics, which passed away in the jet age (LATEST!). It is more important to understand which plane keeps the energy better during turns.
This has much more importance and both planes enjoied here a significant advantage over their contemporary piston A/C, altough we simply do not know how they compare here against each other.

 

[kool kitty89]

I agree. And I think both retain energy pretty well in turns. All the pros and cons have been listed and overall the planes seem to be even, though they are optimized for different roles. And the mach limit is only really important when one is trying to out-dive the other. The Me-262 was a multirole fighter optimized as a bomber interceptor. The P-80 was a good interceptor, but also a decent escort and dog-fighter. The only scenario that would really make sence for the two meeting is if the P-80s were on a strike mission on a 262 airbase (as the Meteors did) or as an escort for bombers under the threat of the Me 262.

But, you're right Delcyros, this discussion is kind of just going in circles. We've already pretty much settled on the characteristics of both craft as I summarized earlier. The only thing that's really left to add is the Fly-off info from Wright Field, with full details of what models of each plane were compared. A stripped-down will obviously outperform a loaded P-80, and almost any 262 configuration will outperform the original L-140 XP-80 in all but agility (and even tat was harmed bu some aerodynamuc problems with the original design).

This discussion has side-tracked so many times we might as well have started new threads for the offshoots. And there hasn't been a whole lot said here that was new compared to RG's previous thread.

 

[Civettone]

The 004D also had better throtle-up characteristics, longer service life, higher rev limit, and lower fuel fuel cnsumption than the 004B.

And with 150 kgp x 2 extra I think it would have gotten better performance: speed, climb rate, etc than the P-80.

The P-80 still has the weapon advantage (unless the Me 262 used an alternative armament)

I don't understand this. The Me 262 had the greatest armament of all fighters in WW2. The MK 108 was a magnificent weapon, especially against fighters where the low muzzle velocity matters less.
And combined with the R4M it has an incredible punch, being able to take out every heavy bomber and finish it off with its guns.

Kris

 

[kool kitty89]

But muzzel velocity matters more when in a high speed doghfight. The .50 cal BMG had excelent balistic properties, very flat trajectory, high velocity, decent ROF, and good range. (~400 m for accuracy and ~1000 m for effective damage) While the MK-108 had a realitively low muzzel velocity and ROF resulting in a weapon that was great aganst bombers but poor aganst fighters. (effective range would be ~100m accurate and ~300 m effective damage) While a single direct hit is devistating its is difficult to score such a hit durring a dogfight, also the shell has to detonate and not bounce off or punch through. (there were a fair amount of duds) The dropping trajectory made it difficult to aim with and the low ROF further limited its chances of a hit. The 6x BMG of the P-80 could fire verry rapidly and in the compact nose mounting, had verry concentrated fire. The ammo load of the Me-262 was also fairly low. (2x 100 and 2x 80 shells in the 262A-1.

The MK 103 had the same projectile but with a much higher velocity and verry flat trajectory and about 2x the range of the 108, at the expence of added weight and lower ROF. I sugested an alternative armament of 2x MK 103 and 2x MG 151/20 cannons, making the armament much more versitile fore mitirole use. I'd expect the 151/20's to hold ~200 RPG each and the 103's ~80 RPG. (as a conservative estimate)

Look around the site, this has been discussed several times and by people with better balitics knoledge than I have. Look through this thread or: http://www.ww2aircraft.net/forum/polls/me262-vs-p-80-a-562.html or search the forum for more info on this.


From RGLunatic:

As for the armament, I totally disagree. The 6 x .50's were far superior for dogfighting than the 4 x MK108's. It is unlikely that the Me262 would have been able to hit the P-80 from any range beyond 100 meters (and even that would require an expert marksmen), where the P-80 could have reached out over 400 meters and touched the 262. The MK108 was an anti-bomber weapon, nearly useless in a high speed dogfight."

Also R4M rockets were devestating against bombers but useless in a dogfight, I'd think they'd hurt more than help since there's virtually no chance of hitting a fighter with them and the added drag and weight lowered performance.

As a side question, Delcyros, you've mentioned the HG series several times and I've been having trouble finding consistant data on the designs (some say only the HG II has the V-tail others say the HG-I or HG-III had it) and in one of you're first posts you said the HG-I had a "35 degree wing inlay", what does this mean?
And any idea where this picture came from? The nacelles are weird and it looks real...

 

[Soren]

Koolkitty98, please don't rely on what people say on other forums as there's bound to be allot of BS involved sometimes, and please don't directly copy their text without always marking them with ""'s or changing them to Italic. Its ok to copy text and post it here, just don't forget to make notice of it, otherwise some people might get confused.

Anyway getting back on track..

The Me-262A-1a P-80A both had approx. the same wing-loading with the same fuel loads, however the Me-262A-1a benefitted hugely from featuring full-span auto LE slats which improved turn performance at all speeds considerably. The Me-262A-1a also benefitted from a higher Aspect Ratio wing which meant a high L/D (Lift/Drag) ratio, keeping the energy loss in turns low compared to other a/c (The Ta-152H benefitted from this as-well)

Getting to performance the Me-262A-1a was superior here as-well, both in climb rate, acceleration speed. The ony comparative test we know of confirmed this as-well. Keep in mind that the P-80A's in service by 1945 didn't perform as well as the later F-80C.

The only a/c of WW2 which which would've been a potential match for the Me-262A-1a was the He-162A-2, but due to shortages in materials quite a few examples of the He-162A-2's would've undoubtedly suffered from a weaker structural integrity.

 

[AL Schlageter]

Now I know 1-3 here will poo-poo this,

In the fall of 1944 in a complaint by KG-51, they requested 3 spare noses for each aircraft, as the guns or gun barrels would work themselves loose in a mission, requiring replacement of the nose. Parts had to be beefed up because they were inadequate to the rigors of field and combat conditions.Parts had to be beefed up because they were inadequate to the rigors of field and combat conditions.

 

[AL Schlageter]

Directional control was great in the Me-262 infact it was excellent. You'd have to go below 160 km/h to loose directional control in the Me-262 (This is with flaps deployed)

Ditching the Me-262 on a field at 160 km/h wouldn't be that risky for the pilot.

Minimum approach speed of the 262 with one engine is 260kph with an altitude drop of 1 to 2m/s. At the airfield boundary the Va speed is 200kph for a normal landing (2 engines).

262 Pilot's Operating Notes

I can't find it now but iirc you said the 262 could do 1000kph. This is 50kph above the maximum allowable diving speed.

 

[delcyros]

I can't find it now but iirc you said the 262 could do 1000kph. This is 50kph above the maximum allowable diving speed.

The following reference should be interesting to You, Al:

Me 262 A-1 Pilot's Handbook, ref: F-SU-111-ND dated 10 January 1946. Issued by Headquarters AIR Material Command, Wright Field, Dayton, Ohio. Classification cancelled; 3 June 1955.

Speeds of 950 Km/h are reported to have been attained at shallow dives of 20 - 30 degrees from the horizontal. No vertical dives were made. At speeds of 950 - 1000 km/h (590 - 620 mp/h) the airflow around the aircraft reaches the speed of sound and it is reported that the controll surfaces no longer effect the direction of flight. (...) It is also reported that once the speed of sound is exceeded, this condition disappears and normal flight controll is restored

This statement implies that high speed tests have been undertaken at least in the US with captured Me-262. I could quote Messerschmidt Aktenvermerke which show that high speed dives have been made in Germany, too (during these dive tests at least two planes couldn´t recover from the dive and crashed, probably beeing supersonic in this event). The above source is also in general agreement with Guido Mutkes experience of a terminal dive.
However, IT WAS NOT ADVISABLE to exceed 950 Km/h TAS, for sure (at least for those, who wanted to attain higher ranks).
There are about two dozen reports, collected by a friend of mine, which cover the issues and show how pilots managed to escape the uncontrollable condition by trimming, jettisioning of the canopy and other emergancy operations. He is about to finish his paper.

As a side question, Delcyros, you've mentioned the HG series several times and I've been having trouble finding consistant data on the designs (some say only the HG II has the V-tail others say the HG-I or HG-III had it) and in one of you're first posts you said the HG-I had a "35 degree wing inlay", what does this mean?
And any idea where this picture came from? The nacelles are weird and it looks real...

The picture You are referring to actually is an artwork originating from Daniele Sabatini:
Daniele Sabatini's Messerschmitt Me 262 HG "Early Variant" Luft Art Images
It does show the Me-262 HG-II as intended, not as executed.
The HG program was to enhance the aerodynamic design of the basic airframe with the aim for even further improved crit Mach figures (we suspect, altough we do not have a proof, that the final HG-III was intended to break the sound barrier with a crit Mach figure of >0.96). It does not seem that the experiences gained should be overtaken for immediate mass production, altough several aspects were considered for variants with more powerful engines.
The HG-I (Werknummer 130 004, previous designation V9 with the markings VI + AD W) started it´s high speed test flight program in january 1945.
The standart -262AV WN: 130 004 had the following modifications:
1.) new center wing section (between fuselage and engine nacelles) to increase the wing sweep locally (between fuselage and nacelles) to 35 deg. max (tapered to normal sweep at the nacelles).
2.) high speed, shallow canopy
3.) new, swept back tail
The new tailplane resulted in some stability issues at low speed, the canopy and wing filet increased speed noticably. Altough the test pilots (Baur and Lindner) didn´t liked the reduced comfortability of the shallow canopy.
I have not been able to find definitive speed measurements, altough they were made with the HG-I. Crit Mach figure is estimated to have increased, too, altough again nothing definitive to know of. There is a film of the V-9 landing, broadly known. It´s final fate is unknown to me.

The HG-II (Werknummer 111 538 ) consisted of a new, general wingsweep (35 degrees), improved engine nacelles, shallow canopy and swept back (normal) tailplane. There is also some evidence suggesting that the Werknummer 111 538 received Jumo-004D4 engines. The plane was finished and sheduled for flight testing in early 1945. There are no photos of the plane known to exist and Werknummer 111 538 was damaged during taxiing trials just before entering the Messerschmidt high speed flight test. There were no attempts made to repair the plane due to the closing stage of war.
It was indeed discussed to refit Werknummer 111 538 with a V-tail altough the plane was finished with the HG-I normal swept back tailplane.

best regards,

 

[kool kitty89]

Sorry Soren about the quotes, and I didn't say I agreed with what they said, I just wasted some opinions of what they said. Though it is sertainly true about all the confusion of the fly-off.

I'll agree that the 262 had pretty nice handling, and I already assumed that with the cleaner form, the 262 would have better energy retention. But the P-80's air-brakes gave better dive recovery, and would probably allow a tighter turning radius, albeit with a greater loss of speed.

Soren, I beleive you agree on the weapons topic though. As the P-80's guns were obviously superior in a dogfight, though I certainly agree that the 262 could have easily used alternative armaments which would have offered better all-around performance. Since they were able to fit 2 of each: MG 151/20 MK-103 and MK108 all in one Me 262's nose. (I think 2x MG-151/20 and 2x Mk-103 would have been the most practical, as both have good velocity, range, and trajectory, the 30mm has the "punch" needed aganst bombers and the 20mm would have the ROF necessary for fighters, though with its flat trajectory, the 103 would be OK against fighters even with the low ROF)

While I maintain that the BMW 003 was superior in all technical respects to the 004 (size thrust/weight, spool-up, and efficiency), but the 004 was simpler and easier to manufacture. I also agree that the 003 would have not been a great choice for the Me 262 as it didn't have the necessary thrust for the large a/c. The Me 262A-1b was a test program usig production quality 003 engines and its top speed was less than 500 mph. Though I also maintain that the HeS-30 (109-006) engine was superior to both engines, and IMHO woult have been ready long before the 003 so they should have dropped the 003 and had BMW and Jumo focus on class-2 designs while Heinkel-Hirth would focus on the HeS-30. The 004 should have stayed since it would still likely be the first ready for production. Though the 109-006 was also superior to many class-2 designs as 2 of it had less frontal area than most comparable class-2's and it was verry light.

Thanks for the info Delcyros. Though swept normal tail would likely offer more control/manerverabillity than a V-tail of the same size, but with more drag. It would need a fully-trimmable tail (variable incedence) to maintain control near mach 1. Would a V-tail also allow control in transsonic flight though?

I'll assume then that there were various designs for the HG III, all having the same general layout, but with some differences. There are so many different pictures of the HG III designs on the web. (I think it was planned to use 2x HeS-011 engines on this model) See these for the "varients" I mean (including a development of the HG-III with a tail-burried cockpit that is often called the HG-III, even though it was a totally separate design): Gino Marcomini's Messerschmitt Me 262 HG III Luft Art Images Reichdreams Dossiers New Page 0 Cape Hobby Gift - Aircraft Resin Models - Antares

Below is the closest to the description of the "definative" version of the HG III I could find, and below it is the "very strange Me 262-Lippisch project" which is sometimes misidentified as the HG III or "HG IV"

 

[AL Schlageter]

delcyros, I got the 950kph maximum diving speed from a translation of L.Dv.T-2262 A-1 and A-2, dated Jan 1945.

This translation can be found in the Classic 4 book series on the Me262 by Smith and Creek.

 

[Jank]

P-80 in Foggia, Italy.

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[kool kitty89]

IIRC, the 2 YP-80As stationed in italy were the only ones to see active service in the war, though they only flew a few patrols before they were grounded and never met any enemy a/c. Though, at least their pilots managed to fly them without serious problems, maby they were introduced more throughly to the plane's characteristics and procedures and were thus able to deal with the teething problems. (throtle regulation and the back-up fuel pump operation; as both would lead to engine failure and flame-outs some cases)

Also, Soren, any oppinion of the 2x MG 151/20 and 2x MK 103 layout for the Me 262? I know the Me 262A-a/U1 had two 20 mm MG 151 cannon, two 30 mm MK 103, and two 30 mm MK 108 cannon, but this was problematic and would limit ammo capacity, so eliminating the MK 108s might eliminate this. The MK-103 was heavier, but had better balitics and the ROF wasn't too much lower than the 108, the recoil would be higher, but as you said the 262 could handel it. The barrels would protrude a bit, but that's not major and with the lighter MG 151/20s the weight would be about the same as 4x MK 108s. This armament is also the one planned for the Me 109TL backup for the 262, though it was to have provisions for 2x wing-root mounted MK 108s.

 

[AL Schlageter]

Also, Soren, any oppinion of the 2x MG 151/20 and 2x MK 103 layout for the Me 262? I know the Me 262A-a/U1 had two 20 mm MG 151 cannon, two 30 mm MK 103, and two 30 mm MK 108 cannon, but this was problematic and would limit ammo capacity, so eliminating the MK 108s might eliminate this. The MK-103 was heavier, but had better balitics and the ROF wasn't too much lower than the 108, the recoil would be higher, but as you said the 262 could handel it. The barrels would protrude a bit, but that's not major and with the lighter MG 151/20s the weight would be about the same as 4x MK 108s. This armament is also the one planned for the Me 109TL backup for the 262, though it was to have provisions for 2x wing-root mounted MK 108s.

Since it was missed, here it is again:

In the fall of 1944 in a complaint by KG-51, they requested 3 spare noses for each aircraft, as the guns or gun barrels would work themselves loose in a mission, requiring replacement of the nose. Parts had to be beefed up because they were inadequate to the rigors of field and combat conditions.

The nose of the 262 had trouble even with only 2 cannon fitted in the jabo.

 

[DerAdlerIstGelandet]

IIRC, the 2 YP-80As stationed in italy were the only ones to see active service in the war, though they only flew a few patrols before they were grounded and never met any enemy a/c. Though, at least their pilots managed to fly them without serious problems, maby they were introduced more throughly to the plane's characteristics and procedures and were thus able to deal with the teething problems. (throtle regulation and the back-up fuel pump operation; as both would lead to engine failure and flame-outs some cases)

They did not fly the YP-80A's without problems. They were even grounded after a crash.

Oh and Jank please downsize your siggy.

 

[delcyros]

Also, Soren, any oppinion of the 2x MG 151/20 and 2x MK 103 layout for the Me 262? I know the Me 262A-a/U1 had two 20 mm MG 151 cannon, two 30 mm MK 103, and two 30 mm MK 108 cannon, but this was problematic and would limit ammo capacity, so eliminating the MK 108s might eliminate this. The MK-103 was heavier, but had better balitics and the ROF wasn't too much lower than the 108, the recoil would be higher, but as you said the 262 could handel it. The barrels would protrude a bit, but that's not major and with the lighter MG 151/20s the weight would be about the same as 4x MK 108s. This armament is also the one planned for the Me 109TL backup for the 262, though it was to have provisions for 2x wing-root mounted MK 108s.

I think the weaponry proposal suggested by You is reasonable. To hit something in a deflection shot requires two points:

1.) a reasonable flat trajectory to ease aiming
2.) a good volume of fire.

The P-80´s 0.50 cal M2 (no M3 prior to the late 40´s installed in P-80´s) is a uniform, 6 barrel arrengement (= 80 rounds per second).
It has a muzzle velocity of 870 m/s. and an avg. rate of fire of 800 rpm + one of the finest ballistic properties. The 48g. projectile will drop below Mach 1.5 according to RG at an estimated 900m distance (at sealevel, without taken plane speed into consideration). At 300 m average firing distance, it will have a remaining velocity of 736 m/s. We therefore may conclude that the conditions for 1.) and 2.) are fullfilled perfectly.

Regarding the volume of fire, we should note that at any given time at 300m distance, the mean distance between the projectiles is 9.2m. for the .50cal BMG and the time elapsed between two succeeding hits at this condition is 0.0125 sec. For a very bad high angle (near vertical) deflection shot a plane moving at 166 m/s (~600 Km/h) may result in a .50cal hit each 2.08m (averagized). Assuming some perfect aim hold, a 10.6m long fuselage will receive approx. five 0.50 cal. BMG hits.

Now let´s turn to koolkittys proposal:
The 2 MG 151/20 have a muzzle velocity of 785 m/s. and a rate of fire of 750 rpm (= 25 rounds per second, total). According to RG the 20mm mine round will drop below Mach 1.5 at 250m. At 300m distance, the remaining velocity is 530 m/s, equaling to a mean distance between each round of 21.2m for the 20mm mine rounds and timeframe of 0.04sec.
Using the same high angle deflection shot as above a 10.3m long target (approx. P-80 sized) moving at 166 m/s. may encounter a 20mm hit each 6,64m. Therefore 1.5 mine hits may be expected here. (barely sufficiant to ensure You hit something at high angle deflection shots)
The 2 MK 103 have a muzzle velocity of 860 m/s and a rate of fire of 420 rounds per minute (= 14 rounds per second for two guns). The mine round will drop Mach 1.5 at ~600m according to RG. At 300m distance the remaining velocity is 662 m/s. (Ausf. A mine round with poorer ballistic properties) and the mean distance between the projectiles is 47.3m (!) with a timeframe of 0.071 sec. between two succeeding hits, equaling to a mean average distance of 11.8m. We therefore would only expect 0.87 30mm hits, which is not enough to ensure that the P-80 get´s hit at all, altough the probability not to hit the P-80 is very small (five out of six passes will hit).

So You have five .50 cal. hits vs. maybe one and a half 20mm and perhaps one 30mm hit...
-of course, the 20mm 30mm mine rounds are MUCH more severe to the P-80 than is the .50 cal API to the -262.


To put this in prospect, the normal, four 30mm MK 108 equipped Me- 262 A1a will result in between 2.65 and 3.5 hits, depending which version of the MK 108 is used, -low muzzle velocity is not always a disadvantage when it comes to compare the volume of fire! But then again, the low ballistic property of the MK 108 will make deflection shots impractical as an event.

My favourite armement would be three MK 103 put into the nose. That gives uniform cal. armement (easier to aim with), good ballistics and enough volume of fire to ensure hitting a target even at the worst possible deflection shot (1.3 hits). A 30mm mine contains about 7.7 times as much explosive as a 20mm MK V HE-round and still nearly twice as much explosive as a 37mm MK4 HE-round. Such a hit will assure destruction (safing a dud or perhaps a wingtip hit) of a P-80.

RG considered an armement of four 15mm MG 151/15 as optimal. This, too has merits. The weapon installment can be done quite easily (no major modification is necessary and the replacement of the guns can be made on the staffel workshop level), requiring only minor differences. The ammo is both, smaller lighter (166 gramm vs. 480 gramm), too, so more ammunition can used per gun (250 rpg for the lower and 200 rpg for the upper pair). The guns would also free up some 160 lbs of weight in the nose.
The muzzle velocity is very high (850 m/s for the AP 960 m/s for the HEI) as is the sectional density of the projectile (the AP), resulting in an extraordinary flat trajectory, as good or better than the excellent .50 cal., easening deflection shooting. You would expect three hits in our deflection shooting model. The AP rounds would go right through the structure (and are particularely good for strafing against lightly armoured ground forces as well) but the HEI rounds does only contain 2.8 gramms high explosive, nearly three times as much as the .50 cal API but not enough to cause significant blast effects. Therefore, I would not prefer this kind of armement as long as not a useful mine round is developed for this gun (this hypothetical mine round would be around 48 gramms and has comparable blast effects to a 20mm Type 99-2 HE round, fired with a muzzle velocity of >1000 m/s).
The armement would be limited to deal with fighters + ground attack, only. It is a very good armemnt if You consider the R4M for bomber hunting, as suggested by RG or the hypothetical mine rounds as sugested by me!

 

[delcyros]

Since it was missed, here it is again:

In the fall of 1944 in a complaint by KG-51, they requested 3 spare noses for each aircraft, as the guns or gun barrels would work themselves loose in a mission, requiring replacement of the nose. Parts had to be beefed up because they were inadequate to the rigors of field and combat conditions.

The nose of the 262 had trouble even with only 2 cannon fitted in the jabo.

The KG-51 used Me-262 A1b´s with a structurally different nose section for the two nose ETC´s. It is possible that the gunmounts were somehow messed up in this event, as structure weight indeed was removed to counter cog issues.
The nose section of the normal -262 (without ETC´s) was very rugged and a formidable weapon placement space. The Messerschmidt AG Aktenvermerke indeed show us an overconfidence with the nose structure, rapidly expanding requirements from four nose mounted 30mm to six and then to a variety of different guns, including MK 112 and BK-5´s.
Neither the Ekdo-262 nor Kdo. Nowotny experienced the troubles which KG-51 experienced, which makes me think it is not related to the armement discussion for the fighter variant.

 

[Soren]

I agree with Delcyros competely on the weapons issue.