Flight Test Data and Aircraft Configuration

[DarrenW]

I've been examining the excellent website WWII Aircraft Performance and was wondering that if the document doesn't state wing racks and external stores being present then can we assume that testing was performed in the 'clean' state?

An example would be the P-47 series of aircraft:

P-47 Performance Tests

Much of these tests do not mention external hard points mounted. My concern would be that in practical wartime use these aircraft would often require at a minimum wing racks so they could carry bombs, rockets, and gas tanks to perform their normal mission. The additional weight and drag of these hard points would of course effect performance in a negative way, even with no external stores present.

Anyone have any insight into how to better interpret the data presented in these test reports?

 

[swampyankee]

Having been a professional consumer of flight test data, but not being directly involved in the test planning, I would assume the production configuration, that is if the aircraft in that block were delivered to the Air Force or Navy without racks, the test report would say nothing unless they were installed, but if the aircraft was delivered with racks, the report would say nothing unless they were removed.

I know this isn't particularly helpful, but I have also seen some pretty glaring problems with the flight test data that I used professionally, usually from bad calibrations.

 

[DarrenW]

Hi swampyankee. Your input is helpful as there may be more uniformity in the configurations than I once thought. Were wing bomb racks considered "normal" for a P-47 in 1944 that this detail was considered unnecessary to mention during these tests? I really don't know.

I've also seen the term "combat condition" used, which for the F6F Hellcat (and probably other US Naval aircaft) meant the mounting of fuselage bomb shackles & "T" bracing, along with faired wing bomb racks and sway bracing.

Maybe someone knows the "common" configuration of other aircraft, which could help determine what state they may have been in during these tests, even if these details are not mentioned in the actual report.

 

[CORSNING]

Hi Darren,
I have found the documents on wwiiaircraftperformance to be mostly
explicative. You do have to read them closely, especially if you intend
to compare aircraft.
My personal opinion is that Mike and Neil have put together without
a doubt, THE finest collection of official documentation of WW2 aircraft
you can find anywhere.

 

[fliger747]

Have seen some (not coming to mind where at the moment) interesting data (I believe it was for a F4U -1A) comparing the drag of various items as well as the effect of cleaning up some common drag products. Also some data is available for planes in common field condition as opposed to specially prepared. Yes it all makes a difference, the takeaway, probably few of the planes met specs for performance in the field.

As much of the data was collected by a test pilot writing on a kneeboard, I expect considerable variation in accuracy.