P-51B-1 Roll Rate

[Ambaryerno]

So I'm sure everyone has seen this chart at some point:

I'm trying to create a spreadsheet that can calculate/predict roll performance, and I'm using the P-51 as one of my reference subjects for Servo Tab ailerons.

However, the P-51 had three aileron stop positions (10, 12, and 15 degrees) and I have no idea which one was used here. The only thing this chart says is that it was done at 10,000ft with 50lb force, and not even what fuel load it was tested at.

I can get my spreadsheet to hit 94deg/s at the approximate airspeed (though due to the nature of the curve it's hard to tell exactly where the peak is) but I'm having a hell of a time getting the tail to line up. I just can't boost the falloff of the curve up to indicated without overshooting the indicated max rate. I've also found while working on the Zero (my model for Unboosted/Frise ailerons) that this chart may not even be accurate (the RAAF tested an A6M3 with a roll rate as high as ~110deg/s at its peak rate).

I haven't had much luck finding any other roll curves like this for the P-51. Does anyone know of one out there I may be missing? There was nothing comparable in the stickied thread.

 

[ThomasP]

If you have not already done so, take a look at this NACA report - it might give you a point to start from. The report only covers the XP-51 and does not mention the eventual range of movement selected for service aircraft. FWIW My understanding is that the P-51B originally entered service with a range of +/-15°, giving the aircraft a much improved roll rate at low-medium speeds. Later on it was decided that it was better to have a higher roll rate at medium-high speeds rather than low-medium speeds, with reduced stick forces, so a range of +/-12° was chosen.

 

[ThomasP]

Also, see the image below, posted by tomo pauk in another thread "P-38 vs P-51: Full internal fuel dogfighting"

It shows +/-15°, but the range of movement in service could be rigged differently in the field. When or if they of standardized on +/-12° at the factory I do not know.

Also, courtesy of drgondog and as mentioned in the NACA report I posted above, the actual design of the aileron was changed and implemented sometime after the XP-51 tests. I do not know when the redesigned ailerons became standard on production airframes, but per drgondog it was definitely done by the P-51B-1 and possibly before.