I'm mainly had a question about the top three US fighters in ww2: p-51, p-38, and p-47.... I've read that the P-47 had a terminal velocity of 600mph....true airspeed. I've been looking for the terminal velocity of the 51 and the 38, for a comparison. I thought i would post here, cause i'm unable to find it, and i know a lot of times there are folks in here who know exactly where to look. I also wanted to know how long it took for these planes to reach Terminal velocity. I know that most planes reach the point of compressibility long before they reach TV, so the figure was probaby never something people paid attention to other than test pilots and the plane's developers. Thanks for the read. enjoy your Sunday Bill
Not sure what you're referring to. I don't recall any aviation stats dealing with 'terminal velocity'. I've been involved with aviation for over 10 years. If you are referring to top speed then it would depend on many things, fuel load (Rember as you increase speed you burn fuel thus reducing weight) weight of the aircraft (Ordance, modle of aircraft, personnel on board, i.e. co-pilot) Generally you've named several of the fastest aircraft the US had however, again top speed is all relevant and more often than not it's not the main factor in designing a great aircraft.
Looking back at this post, the question does seem a bit vague. I'm reffering to terminal velocity, which is when the air pushing against the plane is equal to the force of gravity...therefore...it can't fall any faster. Another way to ask the same question, would be to ask at what speed does the propeller stop producing thrust and instead induce drag??? I opened this discussion on another forum, and several folks went into the mach factors that planes achieved in test flights. p-51 D (mkV) achieved .85, where the P-47D achieved .83. but in combat they were virtually identical. I dropped discussing the P-38 because of its issues with being able to handle a compressibility dive. I'm sure it is a tough fact to find, but for some reason, terminal velocity of the "jug" popped up on my first search. It was debated if the Jug ever broke the sounds barrier, but its terminal velocity of 600-625 mph, kept it from ever being able to do it, despite indicators hitting their stops at the top of the gage. It was difficult to ever know how fast they were going. Hopefully this gives my question a better basis to answer upon. It might have been too vague the way i worded it the first time.
your first post wasn't vague, just a rather specialist piece of information. I'm not an aviation fan but I remember an article when I was a kid,I think in Air Review International (or similar) of a USAAF/USAF pilot interviewed about shooting down a ME262, in that the pilot was surprised the Me262 out dived the P47N he was flying, he regarded that Thunderbolts dive speed better than the P51. Of course this would be the recoverable dive. I asked a friend who taught aeronautical engineering and he said the maximum velocity would depend on the air resistance of the airframe-so the P51 terminal velocity would be higher than the P47, he remarked that the P47 looked as aerodynamic as a brick, but that's the younger generation- I mentioned the F104 to him once and he just looked blank. Steve
Most WW2 fighters in a vertical dive would keep accelerating until they broke up, rather than reaching a stable speed. To take as an example the Spitfire from the RAE high speed dive tests. Starting at 39,690 ft and entering dive, by 31,490 ft the aircraft had reached a speed of mach 0.88, 590 mph. The dive angle started at 0 and reached 40 degrees. Increasing the dive angle would of course greatly increase the force accelerating the plane. The USAAF tested the P-51D at high speeds. From their report: At Mach number of 0.76 a true effect of compressibility became evident in the form of a complete vibration of the airplane...The condition becomes increasingly severe as the Mach number increases and could eventually cause a primary structural failure. ... In each case the pilots reported that the vibration became severe beyond Mach 0.80. In each dive to 0.84 or above the vibration became so severe that the airplane was damaged. It goes on to list damage as buckling of the leading edge of the dive flap, a broken hydraulic line and cracked radiator. According to Francis Dean the aircraft had to be written off at the end of the tests due to damage suffered. All the fighters I know of had limiting speeds applied. That wouldn't have been necessary if the aircraft could be accelerated to a terminal speed. The plane won't stop accelerating then, if it is in a steep enough dive. A typical WW2 fighter prop produced about 1500 - 2000 lbs of thrust. A typical WW2 fighter weighed 5,000 - 10,000 lbs or more. Put it in a vertical dive and thrust will equal weight, plus anything the prop can provide. The RAE include some details of a US dive test on the P-47. Starting at 27,700 ft the aircraft was put in to a steep dive, with angle rapidly approaching 67 degrees. By 19,000 ft the speed had reached Mach 0.861. The pilot reported the aircraft was "well out of control" and he was unable to pull the stick back far enough to stop the plane nosing over and increasing dive angle. He deployed his dive flaps to slow the plane and pull out of the dive.
Do you have the source for this info...i'd like to read it. I found some information that goes into the experimental props made by Curtiss, in an attempt to break the sound barrier before jets could. (1949) Pushing The Envelope With Test Pilot Herb Fisher Bill
From the RAE report: The P-47 is rather an odd aircraft to chose for research in to high speed flight, though. It had a pretty low limiting mach number, which is why it was fitted with the dive recovery flaps. Although those flaps did make the testing much safer. The P-51D dive tests are at the excellent WWII Aircraft Performance Go to the US section, P-51 Merlin engine reports, and close to the bottom is an article called Compressibility Dive Tests Part I on North American P-51D Airplane (Mustang IV), AAF No. 44-14134 And finally here's an extract from the Mustang manual specifying maximum dive speeds: All fighters had such limits imposed, some higher, some lower. It was the job of test pilots to dive these aircraft at high speed, observe the effects, and recommend a safe limit for service use. From Eric Brown, who tested large numbers of aircraft:
wow...great stuff. this should keep me busy for a while...lol Is this also where i can find the info on the compressibility dive info on the P-47??? where you quoted that it reached 0.861 mach before it had to piull up??? thanks Bill
I see the chart, but where is the part that describes the dive and the pilot pulling out of the dive? Or was that your own narration. Bill
There's very little in the report on the Thunderbolt because it was tested in the US, not by the RAE. Also, the RAE were exploring the effects of high mach numbers, not carrying out flight tests on aircraft. The only worthwhile paragraph on the P-47:
