Asymmetric flap deployment

Link to the place I posted the chart originally: https://forums.eagle.ru/showthread.php?t=115584

This websight has both the 2675 and 2899 reports up: http://www.wwiiaircraftperformance.org/p-47/p-47.html (Bottom of the page). As they are NACA test reports they are public domain materials.

Apparently the P-47's flap systems had a weird behavior where one flap would drop before the other flap would. NACA TN 2899 documented the F-47D-30 they were testing showing the left flap deploying to 20 degrees a full two seconds before the right flap moved beyond a 5 degree deployment.

Don't know if this is something you all were aware of or planned to model, or if it has since been fixed on modern surviving airplanes, but it would be really cool to be able to get this what the heck behavior of the plane in there too, if possible.

Thank you,

Harry Voyager

Without looking that seems like something that would be corrected pretty fast and not left as standard.

Without looking that seems like something that would be corrected pretty fast and not left as standard.

In a modern aircraft yes, but that test report was in 1953, and they were explicitly testing that, for plane that first flew in 1941, and on an aircraft that was likely built no later than the middle of 1945. Remember this is the era where you could stick a 400lb fuel tank behind the center of gravity and just tell the pilots not to do any maneuvering until it was drained. We're not quite WWII era, where the bombs are stored loos in a box under your seat, or the pilot is sitting in a wicker lawn chair perched on top of a gas tank, but NATOPS doesn't happen until the 60's.

I've also noticed that both the P-51 and P-38 have reports of pilots using the flaps in combat (whether or not it was effective, there are reports that some pilots would do it in both planes), as near as I can tell, no-one even considered that on the P-47. Along with assorted weird comments in the training manual about when to deploy flaps during the landing patterns it leads me to the suspicion that there was something weird about them that rendered them a really bad idea to deploy during any sort of turns.

Thank you,

Harry Voyager

There is no evidence that this was a problem with all aircraft, just this particular test aircraft.

There is no evidence that this was a problem with all aircraft, just this particular test aircraft.

So that's the next question: do we know whether any of the surviving planes exhibit this behavior? The report does note it, but also notes that it just took some minor pilot inputs to correct.

I'll have to go dig through my manuals later, but I also seem to recall something about an "flaps equalizer bar" that the pilot could check, but may be mis-remembering it. I'm wondering if that would have been related to this. The report does not describe the cause of the effect on that plane, merely that it happened and was correctable.

On 6/7/2020 at 12:17 PM, pmiceli said:

There is no evidence that this was a problem with all aircraft, just this particular test aircraft.

Found it: P-47C Tactical Trials
http://www.wwiiaircraftperformance.org/p-47/p-47c-8thaf-tactical.html

Paragraph 9d specifically, complains about the flap system asymmetry. 

Apparently every single P-47C tested in that trial had asymmetrical flap deployment. Unless the hydraulic flap system was redesigned, and given that we see the same issue in the P-47D-30 used in the later NACA tests, it seems likely that it was not fixed, merely lived with. 

This may add more info

Those tests from F-47D-30.