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Kevin J
Banned
First, I must admit that this is a Battle of Britain map.
Lets imagine that this is 1942/43 and I'm running the Air War in Europe. South of that thin blue line, I want Spitfire IX's to intercept high altitude bombing raids and Typhoons on standing patrols to counter low altitude tip and run raids. North of that thin blue line, Spitfire Vb/c's and P-40F/L's are both perfectly adequate for air defence, but I don't need the later. I want to run a daylight bombing campaign so I want a fighter with altitude performance and range so that they are above the enemy interceptors when they arrive on the scene. So I want Thunderbolts as the turbo superchargers of the Lightning at the time had reliability issues and the only Mustangs available at the time have low altitude engines.
Lets switch to the Med.
Range is important. I have no industrial targets to protect. I have to protect my army in the field, my ports, my bases, my shipping. I want to run both a tactical and strategic bombing campaign. Spitfires are needed as interceptors, Allison powered P-40's to provide cover for my army, Merlin powered P-40's to protect my tactical bombers and Lightnings to protect my strategic bombers. I don't need Typhoons.
Shortround6
Major General
Chart from a P-38 manual
The P-38 was well known for operating close to it's compressibility limit even in level flight. Each plane is different and the P-40 may well have had a higher limit than the P-38.
However the P-40 was slower, especially at over 20,000ft so it was further away from it's limit before commencing to dive even at full level speed.
The late war training manual for the P-40 says on both 61 and 67 "Vertical dives from above 20,000ft are not recommended because of the danger of compressibility".
There is a lot of room between a vertical dive and 45 degree angle dive but it appears the P-40 was NOT free of compressibility effects.
I would also note any pilot flying over the Himalayas who put a P-40 into a steep, high speed dive was asking for trouble. They were crossing ridges (not individual peaks) that ran 14-16,000ft high.
The problem many planes had with compressibility was it delayed when they could start pulling out of a dive. Say it took 6-8,000ft in order to pull out of a dive of a certain speed/angle. If the plane stayed below the compressibility speed range a pilot might be able to start pulling out at 10-12,000ft with plenty of room to spare. However if the plane was diving only 30-40mph faster it wouldn't respond to the controls properly and the pilot had to wait for the thicker, low altitude air to slow the plane (and the thicker air to change the mach number) before he could start to pull out and he might not have enough altitude left to complete the pull out.
The P-38 was well known for operating close to it's compressibility limit even in level flight. Each plane is different and the P-40 may well have had a higher limit than the P-38.
However the P-40 was slower, especially at over 20,000ft so it was further away from it's limit before commencing to dive even at full level speed.
The late war training manual for the P-40 says on both 61 and 67 "Vertical dives from above 20,000ft are not recommended because of the danger of compressibility".
There is a lot of room between a vertical dive and 45 degree angle dive but it appears the P-40 was NOT free of compressibility effects.
I would also note any pilot flying over the Himalayas who put a P-40 into a steep, high speed dive was asking for trouble. They were crossing ridges (not individual peaks) that ran 14-16,000ft high.
The problem many planes had with compressibility was it delayed when they could start pulling out of a dive. Say it took 6-8,000ft in order to pull out of a dive of a certain speed/angle. If the plane stayed below the compressibility speed range a pilot might be able to start pulling out at 10-12,000ft with plenty of room to spare. However if the plane was diving only 30-40mph faster it wouldn't respond to the controls properly and the pilot had to wait for the thicker, low altitude air to slow the plane (and the thicker air to change the mach number) before he could start to pull out and he might not have enough altitude left to complete the pull out.
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- #1,244
I only have the losses for 325th and 79th FG, and the latter I would have to count, as they don't differentiate by type (they flew P-47s after P-40s)
325th FG lost 24 aircraft to enemy aircraft or "unknown" (12/12) vs 133 victories with the P-40, and 43 to all causes. You can see their 'operational summary' here.
79th FG lost about 50 while flying P-40s but I'm too lazy to count tonight (maybe tomorrow)
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- #1,245
I'd say the attempt at misdirection is on your part. The size of the bombs isn't relevant to the presence, or lack, of bomb shackles. Even 100 lb or 40 lb bombs require something to mount them on. The issue under debate was bomb shackles affecting drag. This is a US P-40F of I believe the 57th FG (it's mislabled as 33rd FG) with six small wing bombs.
They also used to have other things when configured in FB mode, for example 'screamers' or sirens often lifted from Ju 87 Stukas, used to terrorize ground forces when bombing, also extra radio masts or directional loops.
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- #1,246
None of this is actually relevant.
20,000 feet was (roughly) the critical altitude for the Merlin XX / 28 so that was where they had their best speed, for example in that RAF test at 370 mph, it was at 19,000 something feet. I am not going to link it yet again.
There is no known issue with the P-40 on compressibility - in theory any aircraft can reach compressibility if it dives strait down at full speed from 20,000 feet but we know they routinely did do vertical dives from that altitude and higher including in over 2400 checkout flights.
I think you are doing more misdirecting here. The P-38 was notorious for compressibility issues which were so bad it basically couldn't perform high speed dives of any kind from almost any altitude until they installed dive brakes on the later models. I don't know of any claims of wartime losses of P-40s to compressibility, even if the manual warns of the potential. If you dived to 500 mph in a P-38F you were very likely going to be in serious trouble. 500 mph in a P-40 wasn't a problem. This is a fact.
Actual P-40 fighter pilots accounts, including several I have posted in this forum, also routinely describe diving from high altitude - vertically. Split S followed by vertical dive was the standard escape maneuver (or one of them) used in the Pacific. There are even numerous accounts of diving and pulling out in a blackout so presumably they didn't consider compressibility a significant threat for that aircraft. You are speculating as to any actual effects, based on a warning in the manual and nothing else.
The question I have is why would you do that? I think you know better.
Shortround6
Major General
Hmm, more misdirection??
Well, that would be a relevant photograph if it was accompanying a speed test that stated the plane was tested with either bombs or the just bomb racks in place. Since it isn't in that context it doesn't mean much.
Most of the tests of the P-40F show it hitting in the low 360s or high 350s, but most (or all) of the tests say the test planes were fitted with at least the belly rack/braces.
I have no problem accepting that a clean P-40F could hit 370mph since the difference is right in line with a number of other aircrafts speed difference with and without a center bomb rack/mount. But then how many of the P-40Fs were operated in combat in NA/Italy without the drop tank? You want the range the drop tank provides (especially on the L) you take the 6-10mph hit to top speed from the drag of the mount/braces. Just like the Bf 109 takes the hit to speed if fitted for a drop tank even if the tank is no longer on the plane in combat.
I see, "no known issue with the P-40 on compressibility" the late war manual just mentions it twice (not once) just for shits and giggles?
Writers of the manual were being paid off by North American representatives?
You actually have it backwards, " in theory any aircraft can reach compressibility if it dives strait down at full speed from 20,000 feet"
Most planes will NOT hit compressibility if they start the dive from under 20,000ft due to the thicker air. The real problems came with starting the dive above 20,000ft (well above in some cases) and exceeding the compressibility limit while still in the low 20s or high teens and then taking (if they were lucky) thousands of feet to slow down/regain control of the aircraft.
Some aircraft broke in mid air and others just dove into the ground due to not having enough altitude to pull out of the dive once the compressibility effect was reduced/stopped due to the thicker air.
This manual was written for student pilots using the P-40 as an advanced or transitional trainer. It does mention a few problems with older short fuselage planes, Like the higher effort needed to manage the controls in a dive and a certain condition that could cause the rudder to lock in the full left position (which could be solved by reducing the throttle). A lot of the Fs and all of the L had the long fuselage so this doesn't apply to them.
Well, that would be a relevant photograph if it was accompanying a speed test that stated the plane was tested with either bombs or the just bomb racks in place. Since it isn't in that context it doesn't mean much.
Most of the tests of the P-40F show it hitting in the low 360s or high 350s, but most (or all) of the tests say the test planes were fitted with at least the belly rack/braces.
I have no problem accepting that a clean P-40F could hit 370mph since the difference is right in line with a number of other aircrafts speed difference with and without a center bomb rack/mount. But then how many of the P-40Fs were operated in combat in NA/Italy without the drop tank? You want the range the drop tank provides (especially on the L) you take the 6-10mph hit to top speed from the drag of the mount/braces. Just like the Bf 109 takes the hit to speed if fitted for a drop tank even if the tank is no longer on the plane in combat.
I see, "no known issue with the P-40 on compressibility" the late war manual just mentions it twice (not once) just for shits and giggles?
Writers of the manual were being paid off by North American representatives?
You actually have it backwards, " in theory any aircraft can reach compressibility if it dives strait down at full speed from 20,000 feet"
Most planes will NOT hit compressibility if they start the dive from under 20,000ft due to the thicker air. The real problems came with starting the dive above 20,000ft (well above in some cases) and exceeding the compressibility limit while still in the low 20s or high teens and then taking (if they were lucky) thousands of feet to slow down/regain control of the aircraft.
Some aircraft broke in mid air and others just dove into the ground due to not having enough altitude to pull out of the dive once the compressibility effect was reduced/stopped due to the thicker air.
This manual was written for student pilots using the P-40 as an advanced or transitional trainer. It does mention a few problems with older short fuselage planes, Like the higher effort needed to manage the controls in a dive and a certain condition that could cause the rudder to lock in the full left position (which could be solved by reducing the throttle). A lot of the Fs and all of the L had the long fuselage so this doesn't apply to them.
michael rauls
Tech Sergeant
- 1,679
- Jul 15, 2016
Perhaps the "truth" for lack of a better word is somewhere in between. For whatever it's worth I have read several accounts of p40 pilots saying they dove them 5 and change without problems but does that mean it was without dangers and a good idea to do on a regular basis? I'm guessing probably not. At least seems like the capability was there if it was ever really needed.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Actually, that's not correct.
To quote:
"We knew about Mach 1 going clear back to the P-36 and the P-40," said the late Herbert O. Fisher, the former chief production test pilot of the Curtiss-Wright Corporation, which manufactured those early Hawk fighters—the retractable-gear successors to the big biplanes. "Nothing could go 600 mph in level flight, but pilots were beginning to dive fighters. We ran into compressibility back in '38."
It's also covered in the book "Curtiss P-40: Long Nosed Tomahawks" by Carl Molesworth.
In one chapter, leading P-40 Ace Bruce Holloway stated: "The P-40 terminal velocity was not high enough to encounter local compressibility phenomena, but it was great enough to run out of enough leg power on the rudder to keep the ball in the middle".
Hey Flyboy....drop the dirge crap..! I am not your enemy and you don't want to be, sonny!
And isn't it great I am allowed to have an opinion and POV from what I read and understand!
Whether you like it or not. I post information I think is correct! Try and have a sane dialog.
Which you are having a problem with. Have no problem getting corrected and actually like it.
Most of what I have are from books up to 50 years old seems badly embellished. Like Caiden's books..
Even the stuff that is well supposedly researched shows many errors because new information has not caught up.
Reading excerpts from Axis pilots in North Africa they stated clearly they chose when to attack or avoid combat. Unless they had a distinct advantage they avoided combat. They Knew the direction and approximate time of every flight. Germans waited for the US and Brits to fly to the battle areas. We could hit their airbases easier than they could hit ours. You can put a bomb on a Me109 but you not going to get very far with it. When you meet your opponent everyday you kinda know where to find them. The main purpose of the Allied leadership was to wreck the Italian and German logistics then their armies. Toward the end of the African campaign fuel was so scarce the Luftwaffe Had a hard time sending any planes up to fight back.
One other statistic that is consistent. Most of the US planes lost were involved on some ground support role.
Either by AA, enemy fighter with a perch advantage, crashing from damage or running out of fuel RTB.
Side note: What I do not understand well enough is how the Allies with a 4-1 Military advantage over the Axis in North Africa.
Struggled so hard to kick General Rommel and Axis out.
The allies main opponent was not the FW 190 it was the Me109 sometimes a few Italian Aircraft. All could get height advantage on the Allied Fighter bombers. The Warhawks with better high altitude performance ran high cover over the fighter bombers. When P38s and Spitfires with a big enough auxiliary tank were available ran cover above them. The early FW190 were not designed as fighter bombers built a high wing loading. Mid - late 1942 rocket launchers added, then experimented with bombs then the dedicated F model for Ground Attack. By the time the F model came out the Germans were already well otw to losing WW2. From my knowledge they were sent to the Russian front and not North Africa. Plus they needed a longer airbase to take off from when loaded. FW190 did have better range and medium to high altitude performance. Which allowed a better energy envelop like the Me109.
Once the energy was bled off where the Performance and Altitude range of the Warhawk was more equal.
Warhawk in Fighter only mode was a deadly foe.
Fighter vs Fighter win/loss ratio was damn near equal in ever dual.
This stat is consistent in just about every US, Brit, Russian, Japanese and Axis record.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Dan...now would be a good time to have a cup of STFU.
Arguing and insulting the forum's Mods is a fast-track to the curb...
Maybe be nice if he did not call me delusional...you think that is fair?
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
The discussion is getting a bit heated and it really doesn't need to be.
Step back, take a deep breath and let it ride.
The quoted number of 592 is for USAAF FG's in the MTO not any for RAF/ Commonwealth or French victories, nor the 49th FG in the PTO . However, different sources give different totals for USAAF P-40's in the MTO. Ray Wagner in 'American Combat Aircraft' has a total of 481 victories and is also the source of 553 P-40 combat losses in the MTO.
On the breakdown of victories by units USAF85 grants e.g. 79th FG 97 victories for the duration flying both P-40's and P-47's. The 57th gets 152 credits for the duration and is the second group to convert to P-47's, so flying that type longer than any of the others. The 324th has 58 credits in the MTO and 30 something in the ETO,, those last in P-47's. I don't recall the numbers for the 33rd FG and haven't bothered counting the 325th.
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Have you got these records?
Schweik,
A war weary aircraft is one that's been over stressed multiple times. The more times it's been "bent" the less life it has regardless of hours of flight on the airframe. Remember the only way the crew chief knew the plane was over stressed was if something was bent or the pilot confessed so rest assured many were not reported. If you want a more modern interpretation then google the Missouri ANG F-15 mid-Air structural failure. Plane was well below its lifespan but failed catastrophically. And inside the flight manual limits.
A line pilot doing what factory test pilots do is asking for trouble. When getting checked out at the edge of the envelope stuff pilots are usually taught by someone who has done it, via an incremental process so as not to get in too far over their head the first time they experience/ see something new.
Your reasoning that because a single factory test pilot routinely exceeded the flight manual on a brand new airplane therefor re-establishes its limit in the field is incorrect. If it were correct then the flight manual would have been "corrected " or changed to reflect that.
Cheers,
Biff
- Thread starter
- #1,259
This refers to actually reaching Mach 1- that is what I meant by "any plane could reach compressibiity if it went fast enough". This also suggests that P-40s actually could reach close to 600 mph as in the two Curtiss tests.
Which is the well known issue (particularly with the short fuselage versions) addressable by using rudder trim. To me the above is proof, or at least evidence, that compressibility was not even really an issue with P-40s unless you got close to Mach 1. Shortround comparing it to the drastic compressibility problems with the P-38 is clearly disingenuous.
- Thread starter
- #1,260
If it did damage to the P-40 to dive at 500 mph I would think they wouldn't do it in a checkout flight, right? You wouldn't want to hand over 2400 damaged planes to combat units.
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