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| Aviation Discussion on the aircraft of WWII. |
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| | #61 | ||||||
| Senior Member Join Date: Feb 2005
Posts: 6,085
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I have never heard 425 mph cruise speed from any P-51 pilot, most veterans tell you that its "Max" speed was around 430 mph at 30,000 ft, and cruise speed wouldnt be close to that RG. Every book and site about the P-51 will tell you the same: http://www.wpafb.af.mil/museum/research/p51.htm https://www.quicktechhobby.com/artic...51_mustang.htm http://www.daveswarbirds.com/usplane...ft/mustang.htm Quote:
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Hey AFDU found out that the Fw-190A turned either tighter or equal to the P-51, and the Fw-190 isnt known for its turning ability Quote:
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__________________ ![]() It was like being pushed by an Angel! - Adolf Galland I'm an educated engineer, so I love being technical and appraising of great inventions. So if you think I am being biased about something: Tell me! Then you'll probably find out that I am not | ||||||
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| | #62 |
| Senior Member Join Date: Dec 2004 Location: Boise, Idaho
Posts: 1,175
| The information I've recieved from P-51 pilots (I'm not finished looking for the truth) is that high speed cruiseis not used, even on light (no guns, ammo or fusalage tank) fully restored P-51s the normal cruise speed is 210 to 265mph depending on Plane/prop/engine setup/pilot. Acording to RR the merlin would fail at the RPMs required for 390mph if extended runs were undertaken. This was fixed after the war for merlins used in commercial aircraft requiring "extended high cruise RPMs". FYI Allison rods are used in hopped up Merlins as is a Very heavy bottom end main bering girdle to rienforce the block. I will accept that the P-51 had a better fuel management system than the P-38. It fell into the WPBs refusal to allow Lockheed to install one. I also believe the Extra thrust ov the weaver effect is mostly theroretical. As I showed (in your other thread) In average conditions the P-38 and P-51 use the same hp/lbs to achieve the same relative top speeds. This would not be true if there was 300-400hp extra being produced by the P-51s radiator. The fact is that the only extra thrust is produced by the heat exchange of the radiator. The expansion of that air (heated) is the only added thrust. Just like a jet engine Compress the air entering, inject fuel and ignite to provide heat expansion then it exits at a higher velocity producing thrust. That maybe more efficent in the P-51 because of the reduction of air velocity due to the expansion chamber allows a more efficient heat transfer but the difference in the added thrust (over other aircraft) is ONLY the added efficency of the heat exchange. That all of this equipment fills in an area of high drag thus eliminating it is more important than any thrust expelled or created. The therory that slowing the air then squirting it through a smaller exit creating thrust is Crap it only works porportionaly to the heat added. |
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| | #63 | |||||||||||
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Here, download the .pdf file for yourself: http://www.lanpartyworld.com/ww2/fil...f/P-51D%20PDF/ You owe me an appology dude. Quote:
Sure the cruise speed could be close to that, it just has to be at an output level that the P-51 can sustain continuously. I really don't see how you can argue with the 1945 revised P-51D/K pilot manual as given to the pilots and mission planners. The first printing might have incorrect info in it, but the 2nd printing includes adjustments for actual combat experiances. Quote:
1) Primary source documents - these are always the best. They include actual test documents involving the aircraft in question. Often these are found on military sites complying with the FIA (freedom of information act), or on fan sites where the author has access to primary source documents and provides that info - usually through scans or photo's of the originals. 2) Manufacture's documents - sometimes these are very good, sometimes not so good. You have to watch out for companies which try to make thier accomplishments look more significant than they really were, and the quoting of special case data as normal case data. 3) Books - these are only as good as the primary source documents and the reading/interpretations upon which they are based. Often mistakes in books become "facts". For example - JANES "All the World's Aircraft" - lists the top speed of the F4U-4 as 425 mph, when we know in fact the top speed was 464 mph. 425 mph was what the USN published back immeadiately after WWII, and this speed was intentially mis-reported. Francillion's "Japanese Military Airfcraft of WWII" - lists the Ki-44II as having mounted 4 x Ho3 20mm cannon. But we know this is infact impossible as the only feeds for this weapon were round drum magazines and their is no way they could have been fit into the Tojo's wings. Most likely this was a translation or reading error. In Japanese the Ki-44 was the "Type two single seat (or engine?) fighter", where the Ki-45 was the "Type two two seat (or engine?) fighter". The Nick could support four Ho-103's, but there is no way the Tojo could. 4) Air Museums - sometimes these are good, but usually they are of very limited depth. It depends on the level of devotion of the particular museam historian to WWII aircraft in particular. Usually, these just regurgitate the most readily available data, usually from the most popular book sources - i.e. Jane's Warplanes or Francillion. 5) Fan sites - these usually just regurgitate data from other sites or books, but occasionally one of merit can be found, such as the fourth-fighter Group or Mark's pages, or especially RING'S PRO DOCS site (see my new post), which offer primary source documents. 6) Pilot accounts - you have to be careful about thes as pilot memories are often poor w.r.t. the actual details, pilot bias is always a huge factor, and pilots often were not given much technical data during the war and what they were given was often incorrect. And also there are a suprizing number of fakes out there - you have to really double check to make sure a pilot you meet at an airshow was really a pilot and not the tow vehicle driver or gas pumper on the airbase. Also, I've met WWII pilots who also flew in Korea who really cannot distinguish one war from the other - they talk about Mig's in WWII! Quote:
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=S= Lunatic | |||||||||||
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| | #64 | |||||
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I really don't see how you can argue with the chart used by actual WWII pilots and planners to determine range/speed settings for actual combat missions. Quote:
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But that is not the proper comparison. The proper comparison is the P-51B vs the Spit IX with the Merlin 66. The engines are of the same HP and the blower gearing is about the same. The Spit IX enjoys about 1000 lbs less weight and is aerodynamically cleaner in the wind-tunnel - yet the P-51B is a good 35-45 mph faster! Quote:
The concept of thrust is not crap. Heating the air causes it to expand and this can either be regulated by the pressure nozzel to maximise pressure and therefore thrust, or it can be let to run free stream which will not maximize pressure/thrust. Holding the air in the compression chamber means that the energy of the expansion occures within that chamber and is applied against the plane when it is vented, rather than occuring after it has been expelled and thus not generating thrust. =S= Lunatic | |||||
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| | #65 |
| Senior Member Join Date: Dec 2004 Location: Boise, Idaho
Posts: 1,175
| The P-38 speed again is back to the METO 414mph? How come the P-51 people always have to handicap the P-38 to prove their point. Try the WEP 443mph if you want to compare them or at least use the same configuration and power setting. Just because it's realese was from Lockheed and was late in the 80's and by a third party at that doesn't make it wrong. It is common knowledge that the P-38 specs are METO throttle settings and the P-51 are WEP. The thrust is only proportional to the heat generated period. The thrust effect is not in pratice significantly greater. the Mustange ie better at managing the boundry layer and the actual heat transfer but it never translated into 300/400hp thats more thrust than a V-1! The heat transfer energy is not that high no matter how efficiently it's managed. You have a theory and a statement that I can't find any verification outside of your posts and only partialy in 2 out of ~50 other references that either one was really effective or utilized to the extent you propose. But I have read they were not. I will continue to look into this and I'll change my mind If I come up with some convincing data. So far I've much more against it than for it. |
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| | #66 | |||||
| Senior Member Join Date: Feb 2005
Posts: 6,085
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But I appologize if i have offended you, as it wasnt intended to be an offensive question. Quote:
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It was an A4 wich was tested by the AFDU against the P-51, and it could follow the P-51 in low-speed turns, and outturn it in High-speed turns.
__________________ ![]() It was like being pushed by an Angel! - Adolf Galland I'm an educated engineer, so I love being technical and appraising of great inventions. So if you think I am being biased about something: Tell me! Then you'll probably find out that I am not | |||||
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| | #67 | ||||
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=S= Lunatic | ||||
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| | #68 | |||||||||
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=S= Lunatic | |||||||||
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| | #69 |
| Senior Member | but can they be sure the -190 pilot knew what he was doing and was turning his tightest??
__________________ ![]() "Reminds me of the time I sank the Tirpitz" comments a Spitfire pilot, "One pass of course, old boy." |
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| | #70 |
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| If it were one pilot, or just one account, perhaps. But it is consistant. P-51 pilots reported that they could easily out-turn the 109 at high speeds, and that they could also out-turn the 190 but not so easily. =S= Lunatic |
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| | #71 | ||
| Senior Member Join Date: Feb 2005
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THAT IS PURE POOP ! In all German tests and mock dogfights the 109 ALWAYS outturned the 190 ! And let me remind you that 109 pilots found it quite easy outturning a P-51 and P-47 at all speeds ! Even a Three cannon G6 would outturn a P-51 ! The "Anton" wouldnt outturn a Spit, only at speeds in excess of 400 mph ! Your stats are for the "Dora's", wich could happily make a dish turn against a Spit and come out the victor, and even more easely do it to a P-51. Quote:
Whenever a "Dora" was in the proximity, the escorting P-51's should be very careful not to attract attention ! If seen the P-51 could forget all about dogfighting the "Dora", as the "Dora" was superior in every aspect of flight except diving ! As for the P-51.... RG there is no way that a P-51 can maintain a 5G turn with NO E loss, its simply impossible ! The Laminar wings from the start simply produced to little lift, and this would get worse if the AoA increased. Also the P-51 didnt have either good Wing-loading or Power-loading to start with, so there's simply no way that what you said is true RG.
__________________ ![]() It was like being pushed by an Angel! - Adolf Galland I'm an educated engineer, so I love being technical and appraising of great inventions. So if you think I am being biased about something: Tell me! Then you'll probably find out that I am not | ||
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| | #72 |
| Senior Member Join Date: Dec 2004 Location: Boise, Idaho
Posts: 1,175
| RG, You have my respect but here I think your off track. The V-1 comparison was ment to be toung in cheek - my bad. The P-38 speed of 414mph when listed with horse power is stated at 1,400 to 1,475. This is Normal full throttle or METO. the P-38J is listed by both Lockheed and Allison at 1,600hp and the L at 1,750hp WEP. Why would the P-51 be derated and not the P-38? As you noted the 450mph P-51B (The faster of the P-51B/D/K line) was at a 5/1 lbs/hp weight not the 5.6/1 of the Mil/Average of the normal statistics a significant difference. AND it's still slower than your claims and under weight! Why would Lockheed internal tests be weighted unequaly - my understanding is that these aircraft were set up Mil/average expected conditions. I think your just keeping the discussion heated up/going! |
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| | #73 | ||||||||
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=S= Lunatic | ||||||||
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| | #74 | ||||||
| Senior Member Join Date: Feb 2005
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It is commonly known that the "Dora" turned alot better than the "Anton" at all speeds, and this is also confirmed several times by Hans Werner Lerche, and ALWAYS by FW pilots ! (Mock dogfights were carried out) Quote:
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__________________ ![]() It was like being pushed by an Angel! - Adolf Galland I'm an educated engineer, so I love being technical and appraising of great inventions. So if you think I am being biased about something: Tell me! Then you'll probably find out that I am not | ||||||
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| | #75 | |
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