Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Viking on April 25, 2007, 08:44:01 PM
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I had the great honor and pleasure of meeting this true Hero and gentleman this evening at our National Aviation Museum here in Bodø.
(http://www.luftfart.museum.no/imagesLANG/Flyfoto_Bodoe_Jan_Wasmuth.jpg)
(http://www.luftfart.museum.no/Om_museet/MuseeLANGT.jpg)
(http://www.luftfart.museum.no/Utstillinger/Images_fly_2006/Spitfire_GD.jpg)(http://www.luftfart.museum.no/Utstillinger/Images_fly_2006/Mosquito_AU.jpg)
(http://www.luftfart.museum.no/Utstillinger/Images_fly_2006/Ju52.jpg)(http://www.luftfart.museum.no/Utstillinger/images2006/Oversikt_militaer_72_Utgaard.jpg)
Capt. Brown’s presentation was held in one of the museum’s auditoriums.
(http://www.luftfart.museum.no/imagesLANG/Auditoriet.jpg)
Capt. Brown was surprisingly fit for his advanced years of 86 and I greatly enjoyed his clear-minded insights and typical British humor.
I recorded the presentation on my digital camera, but unfortunately it can only record 29 minutes at a time, so there are two gaps of about 10 minutes while I was dumping the videos to my laptop.
Each part is about 20 to 30 megabytes and I’m using FileFactory to share the files. When you click on the links you will get to a FileFactory page. On this page you must scroll down and click on the “Download for free with FileFactory Basic” link. You will then get to an advertisement page; watch it or click the “skip ad” button/link. You then get to the anti-bot verification page (with more ads I’m afraid, but hey … that’s how they keep the service free). Type in the numbers/characters as required. You will then (finally) get to download the file by clicking on the “Click here to begin your download” link.
Part 1
Part one starts with Capt. Brown being introduced by a Norwegian veteran whose name I didn’t catch. Capt. Brown then tells us that his presentation will primarily be about the quest for speed from the 1920 up to and beyond the breaking of the sound barrier. He presents some interesting test results and conclusions on the P-38 and P-47 that are bound to be controversial here on this forum.
http://www.filefactory.com/file/8a81d9/
In the ten or so minutes that are missing at the end on Part 1 Capt. Brown told about a dive speed test in the spitfire (flown by another RAE test pilot) where they achieved such a high Mach number that the prop got torn off the airplane along with the reduction gear, and the wings were swept back by the drag to such an extent that there was a 3 inch gap in the leading edge of the wing roots. The pilot was very lucky to make it in one piece, and that speed is till the fastest achieved by a piston engine plane ever. He then went on to the start of the jet-age with the German prototypes of the late 1930’s as we start Part 2.
Part 2
http://www.filefactory.com/file/142ffe/
After Part 2 there was a coffee break and I took the opportunity to dump the video from the camera’s memory.
Part 3
http://www.filefactory.com/file/a1a109/
What Capt. Brown was saying at the end when the video cut off was that the German wind tunnel amazingly had an airstream speed of more than Mach 4 … during WWII (!)
He then went on about how a German aerodynamicist in the 1930’s held a lecture in Italy on the advantages of sweeping back the wings, and that the same person (IIRC) after the war also came up with the delta plan form being the best for supersonic flight. This influenced the British and French in their design of the Concorde. He then finished his presentation with the history of the Concord.
In part 4 he is taking questions (uttered by us Norwegians in horribly broken English), and with my camera’s typical bad timing we start Part 4 in the middle of the answer to the first question. The question was something to the effect of “what's your favorite plane?” - To which he answered that it was the DeHavilan Hornet, and we continue in Part 4.
(Many interesting questions and answers, including the classic Me 262 vs. Gloster Meteor debate we’ve had so often here on the forum.)
Part 4
http://www.filefactory.com/file/0b9811/
We end Part 4 with the last question he accepted and he ended by saying he mostly flew helicopters at the end of his carrier, and that the last time he flew (as the pilot) was in 1994.
Thank you Captain Eric M. Brown for sharing your thoughts, insights and the experiences of your amazing career and life! <>
Now, let’s have a friendly debate on the points and opinions he presented shall we? I’ll let someone else start as I don’t want to give away anything before people have had a chance to view Capt. Brown’s presentation.
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Thank you very much for making this available to us! Also, that is a beautiful area and museum you have!
I'll jump in with one of the controversial things we can discuss for fun.
One of the things Mr. Brown talked about tactical mach numbers and how the 109 and 190 had higher tactical mach numbers (at about 0.75) than did the P-38 (0.68) and P-47 (0.71). He thus concluded that the P-38 and P-47 were not usable against 109's and 190's at high escort altitudes (where it is easier to reach tactical mach speeds) but that the P-51 was usable because it had a higher tactical mach number (at 0.78) than did the German planes.
The thing is, though, there are many factors in addition to tactical mach numbers that come into play (top speed, roll rates at speed, etc.), especially since planes only reach the tactical mach number during substantial dives and can't maintain such a high speed -- they all have to slow down at some point. So, it depends how bad the tactical mach number is. The P-38 clearly had problems diving after 109's and 190's. However, P-47 pilots generally didn't hesitate to dive after 109's and 190's and didn't seem to notice that they were at a disadvantage doing so. Also, the P-47 was the main escort fighter during the period before the USAAF gained huge numerical superiority over the LW, whereas the P-51 started appearing in numbers after the LW was already in bad shape in this regard. It seems the P-47 acquitted itself well against the 109 and 190.
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The P-38 and surprisingly also the P-47 had a tendency to break apart in compressibility dives. Not until the addition of dive flaps (on both the P-38 and the P-47) was this problem fixed. However these weaknesses are not modeled in the game.
From p-38online.com:
"Kelly Johnson would issue a report early in 1942. In the "Study of Diving Characteristics of the P-38", Johnson would state that at a critical airspeed, which varies in altitude, a certain condition exists which causes problems with the airflow. The airflow over the surface area of the wings would separate to produce a special form of stall. At higher speeds, flow separation spreads over the upper surface, and the aircraft tends to be nose-heavy due to a shift in the center of lift. This caused a loss of pitch control. Lockheed engineer Phil Coleman originally specified a dive test plan as early as 1940. He stated that vertical dives should be initiated at 35,000 at modest power settings. The dive would continue until reaching a constant speed at 16,000 ft., and would continue until 13,000 ft. The pilot would then execute a 3 - 4 'g' pullout. The pullout should be completed at 7,000 ft., and should never exceed 570 mph.
Most early combat operational models would suffer from the compressibility problem. However, the problem was not experienced in all theaters of operation. The P-38 did not have compressibility issues while operating in India, the Mediterranean, or in the Pacific. This was primarily due to the nature of combat. In these areas, combat rarely took place above 25,000 ft., and compressibility would not occur if a dive was initiated below 25,000 ft. In Europe, combat operations were normally conducted at high altitudes. Soon, German pilots knew if they were in a bad situation, they could easily dive to safety. The P-38 would be able to dive faster than German fighters, but P-38 pilots were probably more scared of a high-speed dive than enemy fighters.
After extensive testing, the answer to the problem was the use of a dive flap (or brakes). These flaps would be attached to the main spar under the wing. This would offset the loss in lift while in high-speed dives, and would allow the pilot to remain in control throughout the dive. Test pilots Tony Levier and Milo Bircham began a series of dive tests with the flaps. Lt. Benjamin Kelsey was sent by the Air Corps to evaluate the progress of the dive flaps. He took the modified P-38 and proceeded to enter the dive. He had problems engaging the flap as he was beginning his dive. While in the dive, he experienced normal compressibility problems because the flaps were not activated, and the violent thrusts sheared the tail off from the main structure. Kelsey was able to bail out and only sustained a broken ankle. The aircraft was totally destroyed. Another test P-38 would not be fitted with dive flaps for a few months.
Finally, another test P-38 was fitted with the dive flaps and testing was resumed. The Air Corps wanted Lockheed to test the aircraft with 2,000 lbs. of more weight and to start dives at 35,000 ft. The extra weight would cause additional acceleration of the aircraft during its dive, and would approach the critical Mach number sooner. This would be even more hazardous than before. Levier and Bircham resumed testing and would start at a 45-degree dive, and increase each test dive an additional 5-degree until they encountered problems. Levier was the first to encounter problem while using the dive flap. He was in a 60-degree dive, and began having problems when we reached 31,000 ft. The aircraft began to get away from him, even with the flaps deployed. Levier was fighting the aircraft to prevent it from tucking under itself as if it were in a regular dive. He decided to ride it out to see what would happen. He began his recovery at 20,000 ft., but he would not really begin to regain control until he was at 13,000 ft. The instruments registering the strain on the airframe were all over the 100% limit load. Bircham eased it back to the base without putting further stress on the aircraft. This was the evidence they needed to prove the flaps would hold up under an extreme dive, and not lead to disaster like many P-38s prior.”
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Viking..
Isnt he the guy who has been in several Discovery Channel shows?
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Wow.. had never heard of that Museum before...
Looks fantastic!
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Originally posted by Nilsen
Viking..
Isnt he the guy who has been in several Discovery Channel shows?
Yes he has been interviewed for many Discovery shows. He also wrote the "Viewed from the cockpit" column in AIR International for God knows how many years. I enjoyed those immensely as a kid.
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Originally posted by Furball
Wow.. had never heard of that Museum before...
Looks fantastic!
It is, to me anyways. I haven't been to the big museums in the UK or USA, so I can't really compare it to anything. Well worth visiting if you happen to be in the area.
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Originally posted by Viking
Well worth visiting if you happen to be in the area.
like anyone ever "happens to be" in that area :D
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LOL! Actually some do. Since Hurtigruta stops here for a couple of hours on its way north. Plenty of tourists stop by the museum in the summer. When I drove a taxi 6 years ago I picked up a German couple at the museum and drove them to the Hurtigrute pier. During the drive they almost fell over themselves apologizing for the war. I think the section about the bombing of Bodø got to them a little. I still remember the wife trying to translate into English her hustbands words: “Unschuldigen für der Deutsche überfall aus Norwegen“ or something very similar. :D I felt sorry for them.
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Hii,
i never did hear that the P47 felt appart in a highspeed dive!!
The mach08 dives with the P47D-30 show that there wasnt a tendency to fall appart. The dive flaps did help to slow down and get the nose up again, but not to keep the plane together.
It may be the P47 was able to reach speed above mach 0.8, where the structure of every plane get under presure, but i never did read about a damaged P47 due to the speed itself.
Eric Brown did fly many planes and his experience is big, but i always have the feeling his statements are often more his opinion, based on knowledge gained by reading, than by his own experiences.
I did read some of his books, but there are rarely proofs for his statements included, while he always write like its absolut true.
Imho he often make to fast and not safe conclusions, selled as truth!!
On the other hand its always a joy to read what he write(at least for me).
I hope he will get some years more!!
Unfortunately my connection is very slow so it will need some time to get the videos, thanks for sharing this!!!
Greetings,
Knegel
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Thanks for posting, it was worth it just for the 'I flew the Me163 once, and believe you me, once was enough' line.
I was suprised by the tactical mach figures, everything allied seems faster at that height so how do you get to use the advantage?
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Originally posted by Knegel
i never did hear that the P47 felt appart in a highspeed dive!!
The early models literally shook apart in the heavy buffeting. Completely out of control. Also the P-38 had a tendency to lose its tail section in compression dives.
Originally posted by Knegel
The mach08 dives with the P47D-30 show that there wasnt a tendency to fall appart. The dive flaps did help to slow down and get the nose up again, but not to keep the plane together.
The P-47D model got modified with each production batch to improve dive handling, the D-30 also getting the dive flaps. While the dive flaps did increase drag they were not dive-brakes. They increased lift to avoid the plane’s tendency to “tuck under” into a vertical “graveyard” dive and also helped pilots in pulling out of dives. When approaching compression the wings would lose lift due to the shockwaves forming at the leading edge thus nosing the plane down out of control. They would literally fall out of the sky.
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Originally posted by Knegel
Eric Brown did fly many planes and his experience is big, but i always have the feeling his statements are often more his opinion, based on knowledge gained by reading, than by his own experiences.
I did read some of his books, but there are rarely proofs for his statements included, while he always write like its absolut true.
The man is an ex-combat and test pilot and holds the world record for types of aircraft flown and for carrier landings. Furthermore, he survived. Reading his books gives me an overwhelming sense of a pilot with an analytical mind. A test pilot MUST be able to quantify his statements and is also in a position to directly compare aircraft. Biased as biased may be, but I rate his judgement extremely highly.
I do not know if he has flown the P-47 and if so, to its extremes. The limitation on mach numbers is correct, if I am to believe my limited library. On the other hand, I never heard of P-47's being unable to follow/catch 109s and 190s. If I ever get the opportunity to ask him about the P-47, I will.
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Really nice looking collection of planes, it would be nice to visit there sometime as it is not too far away.
-C+
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Very very very nice! Thanks!
That museum looks great! And of course I also envy you to death for meeting mr.Brown.
Regarding the dive speeds, the P47 was indeed claimed as a very fast diver, - pilots like Rall claim that nothing dove faster. I still wonder if the "word" rather relates to initial dive speed, and then the performance of the late P47's.
Tony Jonsson claimed that the P51 would dive with the P-47, and perhaps even better. Now bar in mind that some of those guys flew (and dived) like...nuts.
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From an old post by Hohun:
"About the beginning of 1944 reports begang reaching the RAE of Thunderbolts diving out of control from high-altitude combat, and eventually in March of that year a P-47D was seconded to RAE Farnsborough from the US Eight Air Force for investigation, since it was suspected that the cause was compressibility induced, and the RAE was at that time heavily involved in researach in the transonic flight range.
[...]
Before the next flight, a Machmeter was fitted to the aircraft, and as instructed I climbed to 35,000 ft, carried out a 2 min level run at full power and trimmed the aircraft before pushing over into a 30 degree dive. At Mach=0.72, the aircraft begang to buffet slightly and pitch nose down, requiring a strong pull force to maintain the dive angle. At Mach=0,73 the buffetting increased severely and the nose-down pitch was so strong that it needed a full-blooded both-handed pull to keep the dive angle constant. I had to hang on grimly in this situation, unable to throttle back until Mach number decreased as altitude was lost. The pull-out was not effected until 8,000 ft. Analysis showed that a dive to M=0.74 would almost certainly be a 'graveyard dive'.
I have only subsequently experienced such severe compressiblity nose-down pitch effects in two other aircraft, the Messerschmitt 163B and the Gurmman F-8F [sic!] Bearcat."
(From "Testing for Combat".)
http://forums.hitechcreations.com/forums/showthread.php?s=&postid=2180107&highlight=P47D+seconded#post2180107
Judging by the "I", Brown did indeed dive test the P-47.
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Originally posted by Viking
The early models literally shook apart in the heavy buffeting. Completely out of control. Also the P-38 had a tendency to lose its tail section in compression dives.
The P-47D model got modified with each production batch to improve dive handling, the D-30 also getting the dive flaps. While the dive flaps did increase drag they were not dive-brakes. They increased lift to avoid the plane’s tendency to “tuck under” into a vertical “graveyard” dive and also helped pilots in pulling out of dives. When approaching compression the wings would lose lift due to the shockwaves forming at the leading edge thus nosing the plane down out of control. They would literally fall out of the sky.
Hi,
the question for me is, at what speed and which P47 felt appart??
Afaik the combat P47C/D dont had this problems, at least not more than a FW190 or Bf109. The problems of the P38 are well known, but thats something absolut different.
Since the bomberescort dont had the absolut need to destroy the interceptor, but to drag him away from the bombers, i realy cant see why a limitation of mach0.72 make the P47 not combat worthy in high alt. Mach0,72 is good above the normal attacking speed of a FW190 or 109G. Actually the P47 did proof that it was a very good escort plane vs the 190A and 109G, its only real limitaion was the rather short range(in 1943). It simply wasnt a air superiority fighter, but still a very good escort fighter. In high alt it could outaccelerate/climb its oponents.
Of course the pilots had to get used to the dive limits, but same problem the 109 pilots had as well and the 262 wasnt able to dive more than 30° without to end very fast in a death trap, but its advanced horizontal speed made it more than combat worthy, same imho count for the P47.
The P38 is a other story, but even this plane did suffer more by the engine problems in high alt, than by its dive problems.
Some of the RAE war time statements got prooven as wrong by history. The Hurri also wasnt even to the 109E, although this was their conclusion after making testfights. I think the statements regarding the P47 as escort fighter in high alt are in the same class.
hogenbor,
i dont wrote Brown is biased and i absolutly respect his knowledge, i only particular dislike the way he offer HIS knowledge as truth. This reminds me to Mr. Rall and Galland, who, imho, also made to many, fast , not exact, but good sounding statements, without a proof or clarification.
Greetings,
Knegel
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Originally posted by Knegel
Hi,
the question for me is, at what speed and which P47 felt appart??
Afaik the combat P47C/D dont had this problems, at least not more than a FW190 or Bf109. The problems of the P38 are well known, but thats something absolut different.
Since the bomberescort dont had the absolut need to destroy the interceptor, but to drag him away from the bombers, i realy cant see why a limitation of mach0.72 make the P47 not combat worthy in high alt. Mach0,72 is good above the normal attacking speed of a FW190 or 109G. Actually the P47 did proof that it was a very good escort plane vs the 190A and 109G, its only real limitaion was the rather short range(in 1943). It simply wasnt a air superiority fighter, but still a very good escort fighter. In high alt it could outaccelerate/climb its oponents.
Of course the pilots had to get used to the dive limits, but same problem the 109 pilots had as well and the 262 wasnt able to dive more than 30° without to end very fast in a death trap, but its advanced horizontal speed made it more than combat worthy, same imho count for the P47.
The P38 is a other story, but even this plane did suffer more by the engine problems in high alt, than by its dive problems.
Some of the RAE war time statements got prooven as wrong by history. The Hurri also wasnt even to the 109E, although this was their conclusion after making testfights. I think the statements regarding the P47 as escort fighter in high alt are in the same class.
hogenbor,
i dont wrote Brown is biased and i absolutly respect his knowledge, i only particular dislike the way he offer HIS knowledge as truth. This reminds me to Mr. Rall and Galland, who, imho, also made to many, fast , not exact, but good sounding statements, without a proof or clarification.
But i guess thats normal, cause pilots in general are not politicians. :)
Greetings,
Knegel
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Originally posted by Knegel
Hi,
the question for me is, at what speed and which P47 felt appart??
The early P-47s (B series and perhaps the very early C series) had fabric covered control surfaces. These would often fly apart during compressibility dives dooming the plane and pilot. Also before a recovery procedure was worked out pilots would try to trim out of the dive resulting in overloading the airframe when the plane reached lower altitudes where the controls became effective again. Or in the words of Warren Bodie (a man I believe Widewing respects greatly): “Pilots were running up against compressibility and they were dying.”
Eric Brown test flew the P-47 with a Mach meter installed and found that the speed at where control was lost was Mach 0.73. This is INDISPUTABLE, and totally unacceptable in a high-speed high-altitude fighter. And I’ll take the word of an accomplished test pilot like Eric Brown who actually test flew the plane in question over some armature internet historian who’s peeved that his pet warbird got a bad rep.
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As I recall, from a pure air combat standpoint, he rated the F4U-4, Fw190D-9 and Spitfire Mk XIV as the best prop fighters of WWII. I don't recall which order he put them in.
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Originally posted by Viking
Eric Brown test flew the P-47 with a Mach meter installed and found that the speed at where control was lost was Mach 0.73. This is INDISPUTABLE, and totally unacceptable in a high-speed high-altitude fighter.
I don't dispute the mach 0.73 number -- I'll take his word for it. But I don't think that one statistic alone determines acceptability. I think it is an important characteristic among other important characteristics (such as top level speed, handling at speed, ability to get to high altitude, and handling at altitude). For example, I'd be interested to know the tactical mach number of the P-39 and P-40, which regardless of what their tactical mach numbers are would not have been as good at high-altitude escort as P-47's or even P-38's.
Also, history shows that the P-47 did very well as a high-speed, high-altitude fighter in WWII. In the words of Major General William E. Kepner, commanding General of the 8th Fighter Command in the European Theater, ". . . it was the Thunderbolt that broke its [the Luftwaffe's] back." The P-47 was a major high-altitude fighter from the time the Luftwaffe was still strong until the USAAF had made great strides towards achieving air superiority. It was the fighter that most presided over the demise of the Luftwaffe.
The top-scoring fighter group in the European Theater (the 56th) flew P-47's. The top two highest-scoring American aces in the European Theater flew P-47's, and six of the top ten in the 8th Air Force flew P-47's. Most of the fighters in Big Week, considered a major turning point for Luftwaffe fighter opposition, were P-47's.
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Originally posted by Brooke
I don't dispute the mach 0.73 number -- I'll take his word for it. But I don't think that one statistic alone determines acceptability.
What you call a statistic I call a serious flaw. When reaching compressibility speed the plane literally fell out of the sky completely out of control. The 109 did not do this, the 190 did not do this, the Spitfire did not do this, the P-51 did not do this.
I do not dispute the accomplishments of those who flew the P-47 in combat. However I argue that those accomplishments were in spite of the P-47’s flawed dive characteristics and if anything makes the pilots’ accomplishments that much greater.
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Originally posted by Angus
Very very very nice! Thanks!
You’re welcome :)
Originally posted by Angus
That museum looks great!
If you ever find yourself in the neighborhood I’ll show you around! :)
Originally posted by Angus
And of course I also envy you to death for meeting mr.Brown.
:D
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Originally posted by Viking
What you call a statistic I call a serious flaw. When reaching compressibility speed the plane literally fell out of the sky completely out of control. The 109 did not do this, the 190 did not do this, the Spitfire did not do this, the P-51 did not do this.
I do not dispute the accomplishments of those who flew the P-47 in combat. However I argue that those accomplishments were in spite of the P-47’s flawed dive characteristics and if anything makes the pilots’ accomplishments that much greater.
I don't think that the P-47 had flawed characteristics in this regard. Every WWII aircraft has a tactical mach number, and it is not a flaw for the P-47 to have one. Yes, the P-47's was slightly lower than the LW planes (0.71 vs. 0.75), and the P-51's was slightly higher (0.78 vs. 0.75). But they all have finite tactical mach numbers, including the LW planes, the P-51, and the Spitfire -- they all have speeds that they can reach but beyond which they are not maneuverable.
For example, I've read accounts of P-51's hitting compressibility. In fact, a couple of months ago, I went to a talk at my local flight museum, the Museum of Flight in Seattle, and heard a talk by Clayton Kelly Gross, a P-51 ace who, among other aircraft, shot down an Me 262 piloted by Walter Schuck (who bailed out and survived and whom he met after the war). Mr. Gross told about seeing a 262 far below him, going into a vertical dive in his P-51 to go after it, hitting full compressibility, completely losing control response in his P-51, losing all interest in and notice of the 262 while attempting to regain control, getting it back gradually as he got to lower and lower altitude, commencing a careful pullout so as not to rip his wings off, and finding himself screaming along miraculously right on the tail of the 262, which he then put a good burst into.
Now, if instead of it being a flaw to have a tactical mach number, you mean that the P-47, once exceeding its particular tactical mach number, was flawed because it was more prone to structural failure or inability to recover at lower altitudes than were the LW planes, the P-51, or the Spitfire, I don't know about that. I haven't read or seen any statistics or even anecdotal accounts that it was more susceptible to failure in compressibility or more prone to non-recovery. The P-38 without dive flaps, yes -- but not the P-47.
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I'd think the P-47 would outaccelerate anything else in a dive. Diving 109s and 190s were possibly caught and shot down before the P47 reached its critical mach number.
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Impressive museum
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Originally posted by Brooke
I'll take his word for it.
Don't, it's incorrect. There is a wealth of data that disproves this figure.
See the 190 Vs p-47D diving thread. P-47s had the same placarded max dive speed as the P-51.
P-47s suffered no more from compressibility than did any other modern fighter of the era. The fact that it operated at extreme altitudes made encountering compressibility more common place. The F4U and F6F were placarded with lower max speed limitations. The fact that these fighters rarely operated above 25,000 feet meant that they had much fewer opportunities to get into long, high-speed dives. Still, there were fatalities from diving these fighters too fast as well. There are documented crashes of P-40s where compressibility was ruled the cause. It was not uncommon for 109s and 190s to go straight into the ground as well. Some were captured on gun camera film.
P-47D dive data from here. (http://mitglied.lycos.de/luftwaffe1/flight/compressibllity/flight_compress.html)
(http://home.att.net/~c.c.jordan/JugDive.jpg)
My regards,
Widewing
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Originally posted by Widewing
P-47s suffered no more from compressibility than did any other modern fighter of the era.
This is … incorrect. The P-47 would “tuck under” when approaching critical Mach thus forcing the plane into an even steeper dive. Of all the WWII fighters Brown flew only three suffered from “Mach tuck”: The P-38, P-47 and F8F Bearcat.
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Viking.....nearly every fighter capable of diving into compressibility confronted the phenomenon of "mach-tuck." All that was required for most of these aircraft to encounter mach-tuck was sufficient altitude to build up to their critical mach number in the dive.
P-51D: In a dive compressibility effects were indicated by instability, uncontrollable rolling or pitching, stiffness of controls, or combinations of these along with vibration. Nose heaviness (tuck under) was noticeable, and became more severe with speed increases.
F4U: Vought test pilots performed many high speed dive tests. On some early ones Mach 0.75 was reached, and considerable buffeting and tuck-under was encountered. A limiting envelope for F4u-1D was defined based on the testing, and service pilots were instructed to stay within it. That envelope ranged from Mach 0.63 ad 10,000 feet to mach 0.72 at 30,000 feet.
F6F: Corky Meyer once encountered mach-tuck while test diving one of the F6F-3 dog-ships from 28,000 feet. His instructions were to dive at a 60 degree angle and reach 485 mph IAS (580 mph true airspeed.) At 12,000 feet the nose of the aircraft began pitching down on its own and the elevator controls felt like they were set in concrete. He managed to pull out only after cutting the throttle and reducing his drag. Later inspection of the velocity-G recorder revealed that he had overshot the goal of 485 mph and attained 512 mph. While the horizontal stabilizers were permanently bent (starboard up 15 degrees; port down by 15 degrees) by his ham-fisted, adrenalin-powered pull-out, the robustness of the Hellcat's construction was evident in the fact that not a single rivet was popped across the entire airframe. The Hellcat's mach-limit dive speed was .78 mach at 15,000 feet altitude to keep service pilots from encounter excessive compressibility effects, including mach-tach.
Regards, Shuckins
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There were a host of problems experienced by any of the WW2 fighters that dove to the speeds discussed in both of the current threads...
They were not intended to go Mach 1!!! they could not achieve high subsonic speeds without control issues and stability issues caused by the shockwave over the control surfaces. It was hazardous to do simply because you needed time to pull out, and you needed to know HOW to get them back under control, and not all pilots made it.
Test pilots and combat pilots therefore discussed the problems widely, and many of the reports we refer to in our posts. Some of them refer to absolute maximums attainable, others refer to sensible parameters that average pilots should adhere to where possible.
A little balance and common sense goes a long way.
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Originally posted by Viking
This is … incorrect. The P-47 would “tuck under” when approaching critical Mach thus forcing the plane into an even steeper dive. Of all the WWII fighters Brown flew only three suffered from “Mach tuck”: The P-38, P-47 and F8F Bearcat.
Afaik Brown never got into a "mach tuck" in a P47!!
The 109 did suffer this problem as well, the 262 did suffer it, the 163 did suffer it, simply all planes with normal wings design suffer this.
The propeller planes in gegeral got out of the problematic speed in lower altitudes(less cold = lower mach numbers and more thick air), while the 262 and 163 rather got into a "mach trap", cause they missed the needed propeller drag to get out of this speed.
Greetings,
Knegel
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Originally posted by Knegel
Afaik Brown never got into a "mach tuck" in a P47!!
Why do you use exclamation marks so much?
"Before the next flight a Machmeter was fitted to the aircraft, and as instructed I climbed to 35,000 ft, carried out a 2 min level run at full power and trimmed the aircraft before pushing over into a 30 degree dive. At Mach=0.72 the aircraft began to buffet slightly and pitch nose down, requiring a strong pull force to maintain the dive angle. At Mach=0.73 the buffeting increased severely and the nose-down pitch was so strong that it needed a full-blooded two-handed pull to keep dive angle constant. I had to hang on grimly in this situation, unable to throttle back until Mach number decreased as altitude was lost. The pull-out was not effected until 8,000 ft. Analysis showed that a dive to M=0.74 would almost certainly be a 'graveyard dive'."
- Capt. Eric M. Brown
So you see … he did.
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Hi,
what P47 did he fly and when??
Its new to me that he took part fo the P47 tests.
Greetings,
Knegel
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P-47C and between late January - early March, 1944.
(source: Brown, "Wings On My Sleeve", pp. 70-72)
He also mentions that these RAE tests were requested by Lt.Gen. Jimmy Doolittle, who had just taken over command of the 8th USAAF.
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It's amazing how "Viking" can take any subject from any source and turn it into an America-bashing spree. It's also incredible that's he's trying to paint the Republic P-47 as a ship that wasn't a great diver.
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It is amazing how some insecure people sometimes see "America-bashing" in just about any discussion with some criticism and varying sources which might rattle and shake their "american beliefs" = absolute and indisputable truths :lol
I am not saying that Brown is right or wrong, but where the heck do you see America-bashing here??? :rolleyes:
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I also dont see "american bashing" here. The RAE statements are a fact and not made by Viking!!
Nevertheless, history did show the ability of the P47 and even the P38 to fight in high alt and did proof the RAE wrong, with their comclusions.
And it looks like also the analysis that the P47C in a Mach0,74 dive would be in a death trap got proven as wrong.
Greetings,
Knegel
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The prejudice that the some in the RAF and the USAAF as well, had for the P-47 when it first came to England is well known. They didnt see it as a fighter that could fight in the ETO because of its size. I also think you see some of that "projection" in the RAE docs. Thats not surprising, being that the Spitfire and 109 were @6-7k pounds, and there is this P-47 at 10k pounds.
As for the P-38, the version the RAF got (Lightning I) was a non-turbocharged, non-counter rotating propeller version, and they were very unhappy with it. Its no surprise they were not fond of it either. Also, the notion of twin engined day fighters to operate against other fighters, was not pursued by the RAF or the LW over France in 1941-3, so again, they were suspicious of the very notion of it.
But a/c get improvements, and sometimes the testing on early types does not jibe with how they do in actual combat.
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In Bodie's book, he says that the common belief that the United States would not allow export of the turbosuperchargers is false. Britain ordered the castrated Lightnings just the way they got them, because they wanted to use P-40 engines in them.
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Originally posted by BlauK
I am not saying that Brown is right or wrong, but where the heck do you see America-bashing here???
... In every post ever made by "Viking." Check out the other P-47 thread right above this one right now; Widewing and a few other people seem to also share my sentiment about "Viking" presenting a slanted argument against American airplanes, in this case the Republic P-47 and the Lockheed P-38. So it's not just me that sees it. However, you Krauts are never going to see things my way, so I'm not going to continue this discussion (except to add input on the actual airplane, if necessary).
In "Viking's" world, German airplanes could dive like peregrines, and American airplanes couldn't keep up. That's quite amusing; if it were opposite day, I'd agree and chime in that American fighters easily out-turned those heavy Japanese Zekes and Oscars. And Russian pilots were highly skilled but constantly out-numbered.
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Unlike Benny Moore here I debate my opponent’s arguments, not their person. Nor do I lie by putting words in other people’s mouths. In "Viking’s" world indeed! :lol
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Originally posted by Benny Moore
However, you Krauts are never going to see things my way,
:rofl :rofl :rofl :rofl :rofl :rofl :rofl :rofl
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crap, now i have to change my opinion regarding the P38/47, cause Krauts never going to see things your way and the RAE was penetrated by Krauts. :rofl
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I've always found you to be objective and fair, Knegel; my comment was not directed at you. I was addressing Viking and Blauk, who are in Norway and Finland, respectively. Being a Kraut isn't about one's homeland, it's about one's state of mind; when I hear "Ve ist der master rrrace," then I call Kraut. Oh, well ... this Amerikan pig-dog is tired of arguing. I don't know why I let myself get started here; the kind of person who is going to listen to "Viking" is going to do so no matter what I or anyone else says.
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There has been a lot of argument and acrimony in this topic, but I would like to thank Viking for taking the time to record and then post Brown's lecture at the fine museum that he visited.
Also, even though the discussions have become heated, these discussions are on interesting topics. We are all passionate about these things, and a passionate discussion on these topics, even if heated, is at least to me far preferable to no discussion at all.
I like being among my kind -- WWII aviation zealots -- even when we don't all agree! :) In fact, having different points of view makes it more interesting.
Now, if we can just keep this topic from turning into a scene out of the movie Team America World Police, we'll be all set. :)
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Originally posted by Benny Moore
I've always found you to be objective and fair, Knegel; my comment was not directed at you. I was addressing Viking and Blauk, who are in Norway and Finland, respectively. Being a Kraut isn't about one's homeland, it's about one's state of mind; when I hear "Ve ist der master rrrace," then I call Kraut. Oh, well ... this Amerikan pig-dog is tired of arguing. I don't know why I let myself get started here; the kind of person who is going to listen to "Viking" is going to do so no matter what I or anyone else says.
Oh oh, so you use Kraut as synonym for Nazi and you call BlauKreuz a Kraut??
Thats a pretty personel attack and i only can say you be extremely wrong in this!!
BK is my Squadleader(LLv34), i know him personally(face to face) and i dont know many people with more integrity than him and sence for fair play then him.
I would say its time to put away the "all who are not with me, are against me glasses" and cool down.
Viking use arguments that got offered by the RAE and other testpilots, imho his and the RAE conclusions got proofen as wrong, but i dont saw him attacking anyone, neighter i saw any Nazi behaviour.
To call someone Kraut in the sence of Nazi, only cause he offer arguments againest a allied plane, is uneven more strange, like to call a old fighter/test pilot idiot.
btw, we germans got called krauts already in WWI, this dont have to do with the Nazis. To say all selfnominated "master race people" are krauts would make at least 75% of the white brits and americans in the 1930´s to Krauts.
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What Knegel said.
All anyone has to do is look at Benny's posting history...all the answers are right there. :)
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(http://superherouniverse.com/superheroes/marvel/captainamerica/images/Captain-America.jpg)
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Originally posted by Benny Moore
I've always found you to be objective and fair, Knegel; my comment was not directed at you. I was addressing Viking and Blauk, who are in Norway and Finland, respectively. Being a Kraut isn't about one's homeland, it's about one's state of mind; when I hear "Ve ist der master rrrace," then I call Kraut. Oh, well ... this Amerikan pig-dog is tired of arguing. I don't know why I let myself get started here; the kind of person who is going to listen to "Viking" is going to do so no matter what I or anyone else says.
Calling people nazis again Benny? That’s so like you. :lol