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Was this because of overland use or because of the turbocharger?
According to this report, there was a cover over the redesigned tail-wheel. As for the effects on performance, it does seem that there is a substantial performance effect by removing the tail-hook and fairing it over, removing the catapult hooks, and things of that sort. The airplane's paint finish was about normal for a combat aircraft, and the radio, if I recall correctly, remained installed. The report that you have for the drag improvement for A/C #02334 seemed to indicate the removal of the radio antenna, though the shell-ejector openings were not faired over.The effect of drag reduction for land-based configuration is not significant. according to Dana Bell, It was about +4 mph with hooks and folding devices removed. case for the F4U-1 BuNo.17930, folding devices remained so just +3 mph(2.4 + 0.6, see below chart) for hooks removed and faired cut-out.
High tail wheel was standard for late F4U-1s, but streamlined wooden block type was not standard. However, after take-off, it seems no way to clear effect than standard high tail wheel to performance, because after tail wheel door closed, only half of the wheel was just exposed.
Yeah, I'd imagine! If my calculations are right...the F4U-1's early propeller blades showed a loss of efficiency at high speed high altitude range.
Wait, I thought lean mixture meant a low fuel/air ratio? Is that air/fuel?BuNo.17930 F4U-1's maximum speed 431 mph was for late type land-based configuration with lean mixture
I think you're mixing up horsepower with boost pressure. Manifold pressure stays the same, but a throttling loss is incurred at lower altitudes with superchargers.The P-47's turbo system was far more efficient because unlike the supercharged F4U and F6F it continuously maintained the higher boost pressures from sea level up to critical altitude.
You thought right. Your understanding appears a little confused. Theoretical peak power occurs at the ideal, or stoichiometric fuel/air ratio, which is at or near lean mixture peak cylinder temperature. So best power occurs at lean mixture settings. The problem is that most engines can't sustain those temperatures for long without overheating and detonating.Wait, I thought lean mixture meant a low fuel/air ratio? Is that air/fuel?
I thought the rich mix was basically right up on the ideal mix for peak power.You thought right. Your understanding appears a little confused. Theoretical peak power occurs at the ideal, or stoichiometric fuel/air ratio, which is at or near lean mixture peak cylinder temperature.
I'd have figured excess fuel would just smother things if you didn't have enough air...Rich mixtures don't GIVE you more power, they help you SUSTAIN more power by cooling the cylinder temps and holding off detonation.
I thought the rich mix was basically right up on the ideal mix for peak power.
I think you're mixing up horsepower with boost pressure. Manifold pressure stays the same, but a throttling loss is incurred at lower altitudes with superchargers.
Oh no, he just might do that.stoichiometric fuel/air ratio
Read up about this!
It was a misunderstanding. Early on, I thought rich meant too much, lean meant too little for optimal and stoichiometric was right on the middle; then I remember seeing a number cited for rich a long time ago (and that's probably the problem), and I think it was 1/6 (fuel/air) which seems very little (might sound stupid but I figured the numbers would be like 1/3 based on the fact that 65% of the air in the combustion chamber was unused), so I guessed the rich mixture was the ideal for power, and lean was best for fuel economy: I'm not sure where I got these ideas from.stoichiometric fuel/air ratio
Read up about this!
When will you stop guessing? If you think it is important read up on it and remember it?It was a misunderstanding. Early on, I thought rich meant too much, lean meant too little for optimal and stoichiometric was right on the middle; then I remember seeing a number cited for rich a long time ago (and that's probably the problem), and I think it was 1/6 (fuel/air) which seems very little (might sound stupid but I figured the numbers would be like 1/3 based on the fact that 65% of the air in the combustion chamber was unused), so I guessed the rich mixture was the ideal for power, and lean was best for fuel economy: I'm not sure where I got these ideas from.
Regardless, I stand corrected.
BTW: The ratio for gasoline is 1/14.7 fuel/air. No idea what jet-fuel would be, but if I were to make a guess, I would figure diesel would be closest.
According to this site, the ratio is about 15.06%When will you stop guessing?
THINK about this for a second. Would it make sense to have a cockpit mixture control that in its normal range of operation was capable of flooding the engine or leaning it to failure in flight? Would you want to fly that beast? So does it make sense to worry that selecting rich mixture might "smother" the engine?I'd have figured excess fuel would just smother things if you didn't have enough air...
I kind of get what you're saying, the ability to get the most horsepower for MAP across the entirety of the performance envelope.Yeah I could have worded that better. I should have said that the turbocharger allowed for a constant realization of boost pressures which resulted in constant horsepower, as there were no shift points along the way to detract from maximum horsepower being attained from S/L to critical altitude.
I should have used a different word than smother, that does sound similar to flooding the carburetor. I meant something more like it'd reduces combustion to a degree.Would it make sense to have a cockpit mixture control that in its normal range of operation was capable of flooding the engine or leaning it to failure in flight?
It's not so much an issue of flooding the carburetor as it is of making the mixture to the cylinders too rich to support combustion. ("Yes, Virginia, it is actually possible to do that"). Clearly you've never adjusted the mixture screw on a lawn mower engine.I should have used a different word than smother, that does sound similar to flooding the carburetor. I meant something more like it'd reduces combustion to a degree.
Sorry I misspoke (ellipsis) even if some of these modifications eventually became standard on production aircraft.
I think there seems no 'special tail wheel faring' for F4U-1 BuNo.17930, In my view, It was steamlined wooden block and of course included in photo I uploaded. to be exact, I don't know what 'fairing' you mentioned.And just to make clear the photo you posted of BuNo. 17930 was obviously (ellipsis) special tail wheel faring wasn't installed at that time:
Same as above. see what the report says exactly.So the question remains, if BuNo. 17930 was indeed basically a standard land-based F4U-1 in service at the time, why would they bother mentioning those details as modifications, and why were they so interested in knowing how they effected performance? My feeling is that if those modifications were already being included in production aircraft there would be no need to mention them in the report.
According to Dana Bell, 965 FG-1s were delivered with land-based configuration, It's one of the factory built version.Another "modified" aircraft (ellipsis) faired over.
This is interesting as the report you referred to earlier estimated a speed gain of up to 8 mph with (ellipsis) we get a net gain of 6 mph (ellipsis) back into the equation:
Firstly, remember the end of my paragraph you quoted. I wrote 'for example, Corsair's drag cofficient for install all six guns was just equivalent to catapult hook, so even at the worst, the effect is only slight as below chart.'FWIW (ellipsis) 3 mph increase in speed. (ellipsis) seeing that it had more slots to be taped over:
Ok, you got me here, I never consider ACP documents as actual "test reports" (ellipsis) I'm curious which "flight tests" they are referring to.
Page 51 of the ACP specifies that it's a 6443A-21 propeller with a diameter of 13'4". as described above, multiple ACPs for the same a/c do not exist until a new revision is issued.While I don't outright (ellipsis) 13' 4" propeller making that kind of speed?
Remember what I wrote in the previous post. what I just expected based on the data actually obtained.Not quite (ellipsis) anything is possible.
Could you (ellipsis) F6F as well.
According to (ellipsis) jibe with your figures of 407 mph @ 24800'.
Lastly, I don't understand about denying official performance just because didn't find a refered flight test report on the website, even more so if it's not certain that the website contains ALL the Corsair's flight test reports during World War II.
It was official performance cleard with operation restrictions for standard configuration, from actual flight test. If it was not the actual performance, it was specified in the ACP and It also specifies whether it was a production model or prototype.
Hi Dawncaster,
Very nice parade of data, I appreciate all the hard work you went through to provide it. I gave you some more bacon...
So basically your theory is that the performance figures for the F4U-1D's were taken while utilizing auto-rich settings, as this a way to explain why the two ACPs in question show the same Vmax for a 'clean' F4U-1 while using the two different propeller types. Sorry, but I don't agree with this line of logic because by the time the latter ACP was printed (1 August 1945) auto-lean was the accepted mixture setting (pilot manuals confirm this) and one would expect testing to be performed in order to show operational considerations.
I was only suggesting that maybe the performance data shown in ACP dated 1 March 1944 was for an airplane which was fitted with the 13' 1" propeller, even though the document listed the production propeller instead. You insisted earlier that it was extremely common for this propeller to be fitted to Corsairs by this time so that's why I put forth my own theory but you roundly dismissed it and that's ok. We'll most likely not solve this question in the immediate future without new data coming to light. Until then, I will accept that the "official" maximum speed of the F4U-1D is 417 mph, because both Chance-Vought and the US Navy says it is so.
We both can agree however that a dedicated land-based F4U-1D would be faster than the carrier version but by how much is still in debate. Could it be the 8 mph difference seen when comparing official and non-official figures (417 mph vs 425 mph)? I don't know but it could be one possibility for the disparity.
So even with these questions we can still say with a fair degree of certainty that the F4U was faster than the F6F at all altitudes, as long as power settings and configurations were similar. The amount of the speed differential however has yet to be fully determined.
For propeller blade design and suggestion about it, my lack of explanation seems to have caused the problem again. I wrote 'new 6501A-0 propeller blade start service with VF-17 in solomon campaign and many F4U-1s have replaced propellers with this new type', but I didn't mean it was extremely common. for example, If the limited to F4U-1 of VF-17, it could be said to be common. but if expand the target to the entire F4U-1s in operation, there were far more old 13'4" propeller than the new 13'1" propeller. to be exact, many F4U-1s have been replaced with new propellers, but not much compared to the whole. I just wanted to say it started service early and was not unique. well.. I doubt that I expressed it correctly this time. In conclusion, considering the characteristics of the ACP mentioned in the last post, It's highly unlikely to be the performance of the 13'1" propeller.