Soren said:
Hmmm.. yeah lets do the math "Correctly" this time.
Um, your math and my math are identical except you chose to use metric where I used english measurments? How does that make Your figures more "correct" than mine?
BTW: the R2800-18W made 2450 BHP, not 2350 BHP, though this makes only a minor difference, raising the F4U-4 p/w ratio to 0.44 hp/kg.
The best documented Spit XIV climb to 20,000 feet I've been able to find is 5.1 minutes, for a plane 100 lbs below standard takeoff weight. This compares to 4.9 minutes to 20,000 feet for the F4U-4 at full takeoff weight and sporting two capped pylons. And on top of that, US climb tests are done from brake off, British climb tests are usually done from wheels up, a difference of about 15-20 seconds. How do you explain this? And how is it that the F4U-4, with capped pylons, is also faster than the Spitfire at most altitudes (except very low, and even there the Spit is not much faster) up to 28,000 feet? And with the capped pylons removed, it is faster to over 30,000 feet, significantly so through most of the altitude range!
And to achieve this performance, the Spitfire is overboosting to +25lbs. The F4U-4 could also drive higher levels of manifold pressure, but no specs are available for that. This was simply a matter of the "purple passion" fuel being available.
And on top of that, the Boscomb Down tests used meticulously prepared aircraft flown by top test pilots, where the USN pilot handbook data is taken from active squadron aircraft, usually flown by 3 fresh flight school grads and one instructor. (British pilot instruction books were similar)
Soren said:
Spitfire quality control was not good, planes differed wildly.
Hahaha !!
Yeah in 1940-41 !!
WRONG! I already gave you the tests info in an earlier post in this thread. Boscomb Down Report No. A.&A.E.E./Res/179 -
Mar. 23, 1943
{w.r.t. clipped wing effectiveness and the Report quoted which shows that it was plane dependant because of poor Q/A which Soren disputes.}
Soren said:
No according to most books about it.
And those books are to be taken over the actual test reports? LOL!
RG most reports contradict each other ! These books are based on modern measuring methods !
Surely you are joking. What modern tests have been done to measure this? NONE! This was a British test with definitative results - the clipped wings were useful only on individual planes that rolled poorly, on other individual planes with non-clipped wings that did not roll poorly, the clipped wings gave no significant advantage in roll rate and reduced both climb and turn performance. Clearly the conclusion was that for future production, where better Q/A was expected, clipped wings were not advised.
Soren said:
Both the Corsair and the P-51 were known to use combat flaps at high speeds. Very few other planes were able to do so.
Shiden, Bf-109, Frank etc etc all used combat-flaps. Also flaps will decrease speed nomatter how little you apply them, and the slower the Corsair goes the worse it turns ! (This is generally true for all U.S. aircraft)
First off, as far as I know only the P-51 was able to drop flaps (5 degrees) at speeds above 350 IAS. The Corsair was one of the few planes that could drop flaps a few degrees at speeds above 300 IAS. Furthermore, as far as I know, only the Corsair and the Shiden had automatic flaps.
On the P-51, 5% flaps could be dropped with a relatively small increase in drag and a significant increase in lift/turn. On the Corsair, the flaps could be set to auto mode and would deploy to maximize a turn, very similar to what was done on the Shiden. It should also be noted that quite a few F4U-1's were lost or damaged because of this feature which, on landing could decide to retract the flaps at a bad moment, and as a result on earlier models this feature was usually disabled in the field.
Soren said:
Why do you think they use the .50 sniper guns for anti-vehicle work?
Because your most likely going to hit thin metal at 90 degrees with "Uranium" bullets ! Thats right the Barrett uses depleted Uranium rounds against lightly armored viechles and such. At 60 degrees from vertical the normal .50 cal AP round will penetrate very little armor, and surely not a 1-1.5cm thick engine-block. (A typical European car's engine-block is normally 10-15mm thick, and 5-6mm at the thinnest areas)
Umm, first off depleted uranium ammo is only used for special circumstances. The normal .50 API round is considered capable of destroying most vehicles with a single hit to the engine at ranges up to 1000 meters. Given the accuracy of the weapon, which is not sufficent to hit a man reliably at 600 meters, there is no way to count on a 90 degree hit.
A typical Euro car engine block is made of aluminum, so it may well be 15mm thick. But for a cast Iron block, this is excessively thick, even for an aircraft engine. Even so, a .50 API round would penetrate or at least crack a 15mm cast iron block even at striking angles of 60 degrees. Cast iron is not steel, it is not as strong, and it is much more brittle.
Soren said:
Again wrong! P-47's, Corsairs, and Hellcats took 20mm hits to the front of the engine and survived frequently durring WWII.
No again I am right ! Its amazing you will even mention this, as there's a Gigantic difference between being hit by a 20mm 128g "HE" shell with a V0 of 600m/s from a Type 99, than by a 20mm 160g "AP" shell with a V0 of 860m/s from a Hispano !
Boy, your data on these guns is way wrong. The Japanese Type 99-Mod2 20mm cannon, in service from 1943 on as the main IJN 20mm, was quite comprable to the Hispano, other than having an intial velocity of ~750 m/s (as opposed to 807 m/s). While this makes some difference, it is not nearly so huge as you indicate.
For the Hispano II, here are the real weights, velocties (measured at 90 feet), and penetration data:
Code:
Hispano II - s1 s2 s3 s4 plate - total
--------------------------------------------------------------------------------------
SAP/I - 133 grams - 853 m/s | 5% | 24% | 36% | 9% # 0% - 74%
AP Mk.II - 140 grams - 807 m/s | 7% | 16% | 22% | 24% # 18% - 87%
BALL - 125.5 grams - 860 m/s | 4% | 11% | 11% | 72% # 0% - 98%
HE/I/T (fuse 254) - 120 grams - 868 m/s All detonated at fuselage. All frags except
one spent on sheet 1; one spent on sheet 2.
HE/I (fuse 253) - 130 grams - 860 m/s All detonated at sheet 1. All frags spent
on sheet 2.
Where test layout is a sheet of 24 gauge dural followed by four sheets of 6 swg mild steel followed by an 8mm HH armor plate at 2' spacings. Firing range = 200 yards, angle = 0 (perpendicular). Percentages show the weight of the rounds recovered behind each sheet/plate.
HE/I type rounds were found to cause fires in unarmored self-sealing fuel tanks (German) for 31% of hits.
Source: O.R.S. Ref. F.T. 260 - July 1942 - ORFORDESS RESEARCH STATION
Firing Trials of 20mm H.S. Ammunition Part I. Attack of Aircraft Targets.
M.A.P. Ref: SB 13888 dated 7.3.42 and 19.5.42 (with handwritten notes dated 23.12.42)
Clearly, while the AP ammo was able to penetrate 24mm of HH armor at 200 yards @ 0 degrees (perpendicular), when put into realistic aircraft conditions the penetration is drastically reduced. The report indicates this is because of the yaw of the round. Combine this with more realistic striking angles and the chances of penetrating even the minimum 9.5mm tempered armor of the F4U-4 is quite small.
Soren said:
Jap Cannons werent at all effective against armored parts, and would penetrate very little ! On the other hand a Hispano AP round will take out a Corsair engine with a single shot !
Based on the info above it is extremely unlikely a Hispano round of any type fired from behind would penetrate to the engine. If it did, it would quite likely be mostly spent and do only limited damage. Only on hits from extreme deflection from the side, or from H2H attacks (foolish for the Spit given this matchup), would the Hispano round likely hit the engine w/o having to penetrate at least 18 gauge dural, probably at least one structural member, and then tempered armor plate (much better than HH) ranging from 9.5 mm to 19 mm.
Soren said:
An AP round from a Hispano cannon will go straight through the R2800 engine ! And if the engine doesnt blow up, it certainly is in such a bad shape that it will not be able to pull the plane through any evasive maneuvers.
And a .50 round will penetrate the Griffon just as easily. But unlike the R-2800, almost every hit will result in a destroyed engine. Once the water jacket is breeched, the engine is finished, and the pilot is flooded with steam and cannot see. The R2800 can take a 20mm hit and even if it looses a couple of cylinders it can still likely generate good power for over a hundred miles.
Furthermore the Corsair supercharge and fuel system are much much less exposed than that of the Spit XIV. On the R2800 these all on the back of the engine, but on the Griffon the carb and one stage of the supercharger are on the top of the engine!
Soren said:
What? You mean to tell me you can put magnesium burning at 4000 degrees and a strong oxidizer into a fuel tank with gasoline and not have it go boom? Wow when did the laws of nature change?
If that was the case, then it would have been alot smarter to just use small caliber fast firing machine-guns with API rounds for Fighter vs Fighter purposes.
No, because the API round has to penetrate the fuel tank, and .303 class API rounds cannod reliably do that.
Soren said:
A self-sealing fuel tank hit by a 20mm Hispano round (AP or HE), will always go BOOM.
Not hardly. AP is ineffective period.
For AP/I against an unarmored tank, no fires were generated out of 8 hits (4 above and 4 below the fuel level), evidently the incendiary did not ignite. Against a tank protected by 6 s.w.g. mild steel, of 2 hits above the fuel level 1 caused a fire, and of 14 below the fuel level 4 caused fires (one outside the tank on the exit hole - probably would not have started a fire on a flying plane). Against 8 s.w.g and 10 s.w.g. protection of 9 hits none started fires. Against 14 and 16 mm HH armor, approximately 20-30% of hits started fires. Against 18mm armor, only one of 20 hits caused a fire.
For HE/I/T against unarmored fuel tanks of 50 rounds 16 started fires, and for HE/I of 72 rounds only 24 started fires. For HE/I against 6mm HH armor 9 rounds caused 3 fires, against 8mm HH armor 12 rounds caused 5 fires, and against 9mm HH armor 5 rounds caused no fires.
As you can see, Hispano hits against fuel tanks did not mean a sure fire, in fact, the odds against a well protected fuel tank like on the Corsair would be quite small.
Soren said:
The F4U-4 had over 290 lbs of armor plate and was rated "protected" from the rear against 20mm fire.
Yeah, "Jap" 20mm fire ! It wont last one bit against a Hispano hit !
I've shown you that this is not true above.
Soren said:
But also because the self sealing rubber/plastic compounds were superior
Source ?!
I'll get into this some time soon. But it is a fact. US self sealing tanks at the start of WWII were better than anyone elses tanks at the end of the war.
Soren said:
Look at the chart - it clearly shows 10 minutes WEP + 10 minutes MP.
RG why would two books specifically about the Corsair underestimate the WEP time ?? (Im beginning to seriusly doubt these Internet documents !)
It's not an "Internet Document". Geeze I've given you the source, the US Navy FIA complaince website. What source could be more valid than the classified pilots handbook - used by pilots and mission planners. What is the point of giving documents to your pilots that are incorrect? Especially documents you never expect the public to see! I can see you doubting the 4th fighter group documents, or other documents where the data has been complied - but how can you "doubt" this? You're just being silly!
Because those books were written before the FIA compelled the US Navy to declassify and make available the actual data. The US military gave out Military Power or Normal power data to the public at the end of WWII for most fighters - they didn't want to give away the real specs. Then being the paranoids that is their nature, they didn't declassify it until they were forced to when the FIA laws came into play, which require information to be made public after 50 years unless congress votes specifically to keep it secret. This is further confused by some data being published regaurding performance using lower grade fuel.
It is so clear you must be able to see it. Look at the chart (attached), most of the figures you commonly see associated with the F4U-4 are right there!
=S=
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