Relative turn radius and rate diagrams

[Widewing]

Many of you have seen threads about turn radius and rate data, and I'm sure some found the numbers hard to envision in terms of actual flight.

So, I used film to generate diagrams that show the relative radius and rate between various fighters. This is done by reviewing the film in the Fixed view mode, watching from directly above. Trails are turned on. When the film shows the tightest possible turn radius (without wobbles), I then take a screen shot. The resulting images are combined to make a graphic that displays the data in an easy to understand format.

Clearly, the smallest circle is the best turning in terms of turn radius. However, the circles reveal the relative turn rate as well. If you look at the Spitfire Mk.VIII circle, you will see that the circle overlaps itself. This is because the Spit has a much higher rate of turn than the other aircraft, IE: it gets around the circle much faster. Compared to the P-47D-11 (25% fuel), the Spitfire turns a slightly smaller circle, meaning that under certain circumstances, the P-47D-11 can give the Spitfire a very hard time. However, under a sustained turn, the Spitfire quickly gains the advantage, not only because it turns somewhat tighter, but because it gets around the circle about 20% faster (as indicated by the overlap in the trail)

These tests were done at about 50 feet ASL, and with flaps fully deployed. At least 6 full circles were flown to stabilize the aircraft at their limits. Note that the P-51D has the largest turning circle, followed closely by the P-51B. Not much smaller is the P-47D-25 with 50% fuel, with the P-47D-11 at 50% fuel, followed by the P-47D-11 at 25% gas. The superb Spitfire VIII is on the lower right.

Now, where to find the time to test and graph all of the fighters this way....



My regards,

Widewing

[Kweassa]

Hmm..

 I think in this kind of environment, my "mechanical" method of involving stall limiters might add interesting results for comparison.

 While involving stall limiters does not necessarily offer an entirely accurate information concerning the absolute turn radius (but very close, if I might add, since I've matched some of my old tests in the past, to Boxboy's measurements in his EM diagram, and reached very close numbers), it would mechanically limit all stick input to a certain set value determined by the SL setting - which leaves the plane at a set margin above stall AoA during turns.

 Therefore, if each plane is set at a SL value where just pulling max stick deflection would still leave the plane at an AoA where it would turn without any hinderance or impending symptoms of stall, it would mean that measured data would provide a mechanically valid turn radius data that is completely devoid of human variation or skill factor.

 I'll see if I can try a few tests of my own.


ps) I've always thought P-47 flaps were bullshi*  

[Vudak]

Thanks for the work, Widewing!

I'm curious though - why do you choose to use 50% fuel in some airplanes?  Is there a stability reason for this or do you feel 25% is too low minutes wise for anyone to ever actually use that in a fight?  As in they'd already have long-since egressed rtb?

[Kweassa]

I think he did that to illustrate a point... the P-51s in their lightest fuel load, still being outturned by P-47s with heavier fuel load.

[Vudak]

Ah, rgr Kweassa, thanks, that makes sense.

I'm having one of those days, I'm afraid

[bozon]

Originally posted by Kweassa
I think he did that to illustrate a point... the P-51s in their lightest fuel load, still being outturned by P-47s with heavier fuel load.

Percentage is not a fuel load. Put 25% in both planes and the Jug has a heavier fuel load, but MUCH shorter flight time. If you want to test combat fuel load, that would mean similar flight time. 50% for the P51 gives more time than 75% on the Jug.

The 51 has a larger circle than the D11 and about the same as the D25. It has a better turn rate than the D25 at this radius as you can see from the missing angle. When you slightly increase the turn radius, the 51's advantage in turn rate becomes even greater.

This test was performed with full flaps which I still think has a very generous drag model. How do they compare without flaps? I'm interested to know if this is due to flap modeling or is the 51 inherently turns wider.

[Widewing]

No flaps tests of P-47D-25 and P-51D added for reference..

Remember, my argument is that the drag model update killed the P-51 by a huge increase in drag when using flaps. You'll note that the turn radius was reduced much less that that of the P-47D-25 (as a percentage of the no flap radius). Turn rate is badly effected as well.

This is why I advocate never using more than 3 notches of flaps in the P-51s as the loss of turn rate is not mitigated by the small decrease in turn radius. Thus, my argument that many aircraft benefited from the drag remodeling, but the Mustangs only got worse. This makes the relative difference seem even greater.



My regards,

Widewing

[bozon]

This confirms my feel about the P47s. Turn rate is better without flaps than with full flaps, though the radius is huge (wallowing flapped pig).

Without flaps, the P51 owns the jug. The P51 did not get worse - full flaps on most other planes just got silly.

[clerick]

Do you have any showing the 38 J/L ,and the G perhaps, with and w/o flaps?

[Hazard69]

Yeah I'd like to see some 38 numbers too. Seems the hogs get to out turn the lightnings even more than before these days.

[Fulmar]

Man, where would this community be w/o Widewing.

[TequilaChaser]

Widewing,
in your diagrams did you go for best sustained turnrate with flaps/with out flaps in the different models or did you go for tightest turn radius  with flaps/with out flaps

.....these are  diagrams showing tightest possible turn radius, correct? not best sustained turn rate?

[Widewing]

Originally posted by TequilaChaser
Widewing,
in your diagrams did you go for best sustained turnrate with flaps/with out flaps in the different models or did you go for tightest turn radius  with flaps/with out flaps

.....these are  diagrams showing tightest possible turn radius, correct? not best sustained turn rate?

Smallest turn radius was the goal. Full flaps with WEP. 6 to 8 revolutions to stabilize the aircraft. This is sustained turning... IE: I could fly these circles until bored or out of gas. Typically, the wingtip is within 1/2 wingspan of the surface of the sea. This prevents dipping the nose, increasing speed.

My regards,

Widewing

[TequilaChaser]

Originally posted by Widewing
Smallest turn radius was the goal. Full flaps with WEP. 6 to 8 revolutions to stabilize the aircraft. This is sustained turning... IE: I could fly these circles until bored or out of gas. Typically, the wingtip is within 1/2 wingspan of the surface of the sea. This prevents dipping the nose, increasing speed.

My regards,

Widewing

one can do sustained turning at any speed and achieve any numerous different turn radius' ........

I meant to say best sustained turn speed, I thought I did my bad, verses smallest turn radius........

smallest turn radius sometimes is slower  than best sustained turn rate/speed.... some times not.....plane dependent.......

to clarify...

when I am  trying to find the "best sustained turn speed" I can vary it by 3  mph slower and do worse or I could vary 3 mph faster and do worse

when people test for smallest sustained turn rate, I always assume they are saying this is the best sustained turnrate & speed....when people say this is the smallest turn radius they are talking how tight a turn they can turn on a sustained basis, although it may be slower than the best sustained turnrate/sustained turn speed


btw, like the diagrams nice work as always, WW.....

[Widewing]

Turn radius diagrams for the P-38s were requested, here they are...




My regards,

Widewing