Different turn performances for left and right hand side turns with steep bank angles in military P-51?

[kilo_alpha]

Hello everybody,

recently I read an article on the internet regarding corner speed and sustained turn rates. Out of curiosity, I started experimenting with the military P-51 and tried to do leveled, coordinated turns with 75° bank angle at 2000 feet. The Power setting was 55" MP at 2700 RPM, turn entry speed was short of 300 MPh or 265 Knots. With a bit of practice I managed to do 360-turns to the left side while holding the needle of the vertical speed indicator close to zero. I found out that aligning the seam between the two metal sheets along the centerline of the enginehood on the horizon line results in a more or less level turn. While turning, the airspeed decreased to 280 MPh or 248 Knots quite slowly.

To my suprise, I had to learn that I couldn´t do the same thing to the right side.

Aiming at the horizon in the same manner as for left turns lead to a descent readout of 50 feet per minute. All my attempts to bring the needle on the VSI back to zero by pulling harder on the stick resulted in a rather quick loss of airspeed, which in turn increased the sink rate. Further counteracting by increasing elevator input eventually lead to a stall.

So far, so good.

The funny thing is, in the civilian P-51 I was able to turn in both directions as nicely as in the military Mustang to the left side under the same conditions (including roughly same aircaft weights around 8250 LBS).

I´m having a bit of a hard time fathoming out what causes the different behavior of both variants Here are my thoughts about possible explanations:

1. My installation of at least one of the Mustangs is faulty. I tried to remove and reinstall both planes along with accusim but that didn´t change anything.

2. The flight model of both variants are correct. In that case, steep right hand side turns in the military mustang must have been a big nono during dogfights. The differences between both models aerodynamic wise should be minor.
The only factor I can think of that could explain the phenomenon would be a different center of gravity.

3. One of the two flight models (no offence intended here) has an issue. If it was the civilian variant, I´d still love to understand the reason... maybe torque or aerodynamic effects caused by the prop...


Thanks for taking the time reading my post. English is not my mothertongue, so I hope it is sufficiently comprehensive. I´m really curious what´s causing the different turn behavior for the stangs. Therefore I´d like to hear your thoughts on the topic. Do your Mustangs show the same characteristics? Is there a difference between FSX and P3D?

Best regards,

kilo_alpha

P.S.: I´m using FSX Gold Edition along with Accusim

[HE11DUDE04]

I'd say it's the gyro torque but then both aircraft would suffer from it so this is a very interesting mystery you've discovered. Maybe it is a small error with the flight model

[kilo_alpha]

Hi, thank you for your reply.

I'd say it's the gyro torque but then both aircraft would suffer from it so this is a very interesting mystery you've discovered. Maybe it is a small error with the flight model

Yes, I also thought about torque, gyroscopic or even prop wash effects as possible cause. But then both variants should be affected and probably other planes like the spitfire as well... Did you try how your Mustang reacts under the described conditions?

I´d love to hear Lewis´and Dudley Henriques thoughts on that topic.

Regards,
Kai

[HE11DUDE04]

Hi, thank you for your reply.

I'd say it's the gyro torque but then both aircraft would suffer from it so this is a very interesting mystery you've discovered. Maybe it is a small error with the flight model

Yes, I also thought about torque, gyroscopic or even prop wash effects as possible cause. But then both variants should be affected and probably other planes like the spitfire as well... Did you try how your Mustang reacts under the described conditions?

I´d love to hear Lewis´and Dudley Henriques thoughts on that topic.

Regards,
Kai

I haven't tried mine yet, might take it up now in fact but I'd also like to hear from Lewis and Dudley

[kilo_alpha]

/quote

I haven't tried mine yet, might take it up now in fact but I'd also like to hear from Lewis and Dudley
/quote

Since flawed installations of my P-51's and accusim can´t be ruled out 100%, I´d highly appreciate a feedback about the behavior of your Mustang. Other users are also welcome

[HE11DUDE04]

/quote

I haven't tried mine yet, might take it up now in fact but I'd also like to hear from Lewis and Dudley
/quote

Since flawed installations of my P-51's and accusim can´t be ruled out 100%, I´d highly appreciate a feedback about the behavior of your Mustang. Other users are also welcome

I didn't notice much of a difference tbh but It might be as I'm using the P3D V4 P 51 Mil so hopefully other fsx users will try as well. one other thing could it have been weather differences between tests?

[kilo_alpha]

/quote
I didn't notice much of a difference tbh but It might be as I'm using the P3D V4 P 51 Mil so hopefully other fsx users will try as well. one other thing could it have been weather differences between tests?

Thanks a lot for checking! The weather setting I used were clear skies, no wind. Interesting that there is no difference on P3D. Some feedback of FSX users would be very interesting. I´m contemplating another reinstall.

[kilo_alpha]

Update:

Uninstalled both Mustangs and Accusim and reinstalled in the following order:

wop3_P51

wop3-P51_civ

wop3_p51_accusim

A2A_Update_02_04_19

The differences between both models as described in the initial post are perstitant. Besides that, everything seems to run fine. I´m still bursting with curiosity though. Can anyone please check if they see the same differences in their P-51´s on FSX?

Best regards,

Kai

[Scott - A2A]

There shouldn’t much of a difference between the mil or civ P-51 flight physics so if there is, it sounds like some kind of bug. I will look into this. Scott

[kilo_alpha]

There shouldn’t much of a difference between the mil or civ P-51 flight physics so if there is, it sounds like some kind of bug. I will look into this. Scott

Hi Scott,

thank´s a lot!

Best regards,

Kai

[kilo_alpha]

There shouldn’t much of a difference between the mil or civ P-51 flight physics so if there is, it sounds like some kind of bug. I will look into this. Scott

Hi Scott, did you have a chance to take a closer look into this phenomenon yet? If so, what´s your conclusion?

Best regards,

Kai

[kilo_alpha]

Today I had a bit of time and repeated the experiment at a higher altitude of 18.000 feet with the civilian Mustang. In that scenario it was also easier to maintain altitude during steep left turns (bank angle roughly 75°) compared to turns to the right side. Explanations, anyone? Is this just physics or a dysfunctional installation? Goes this for all high powered prop driven aircraft like the Spitfire, T-60, P-40 etc.? Since I have both P-51 variants only, it would be nice to get some feedback from other P-51 users in the first place and furthermore from users who have one or more of the other mentioned aircraft. Also, is it appropriate to move the topic to the tech support section? I don´t want to be a pain in anybodies neck, I´d just love to understand what´s the cause of the observed behaviour.

Best regards,

Kai

[Lewis - A2A]

Hello Kai,

every aircraft will have a preferred turn, due to the torque happening. In fact during WW2 the Allies after testing captured equipment had specific tactics to counter certain aircraft that involved rolling a certain way as it was known that one way was quicker and could result in the difference between rolling away to safety or getting tangled and ultimately shot down. From the top of my head I believe it was to Spitfire pilots when countering the 190's which had amazing roll rates.

thanks,
Lewis - A2A

[kilo_alpha]

Hello Lewis,

thank you very much for replying to my post.

every aircraft will have a preferred turn, due to the torque happening.

The affection of the aircraft´s roll rate around the longitudinal axis due to torque is something that I read about before in literature and on the internet as well. That torque is also affecting an aircraft´s ability to perform leveled turns in terms that it will stall out rather quickly if turning to the right side, while turning happily to the left side under the same conditions, is something I never heared or read about before (well, guess that doesn´t mean too much, but I just can´t find anything about that on the internet...)

Please confirm or correct me if I´m wrong in drawing the following conclusions from that:

1. all (single-) propeller driven aircraft are subject to that effect, especially high powered ones like WWII fighters and aerobatic aeroplanes.

2. therefore, the effect is modeled in all of A2A´s aircraft that fit in that category (e.g. P-51D´s, Spitfire, etc...)

3. turning to the right side in a P-51 during a dogfight must have been a quite bad idea, unless the opponent´s aircraft was subject to the same effect (meaning it´s prop had the the same turn direction. Also, of course, dogfights didn´t happen in the horizontal plane exlusively too often, except maybe when close to ground level)

What makes that a bit hard to digest for me is that, in opposite to turn performance, I never experienced a notable difference regarding roll rate in both P-51´s, independantly of altitude. In the past I had some opportunities to watch different warbirds performing displays during airshow events, among them several P-51D´s. It never struck me that any of of those aircrafts turn performance is different depending on the direction of the turn. But, of course, it can be doubted that this is notable by eyeball MkI... Also, what I still don´t get is why the effect seems to be more present in the military Mustang compared to the civilian version even when both aircraft are configered to roughly the same gross weight. Basically, up to now I just couldn´t imagine the torque effect on turn performance being so distinctly

Well, I understand that A2A has put a lot of effort in designing the flight model of their P-51´s, even by utilizing data of recorded flights in real aircraft (makes me wonder if steep, leveled turns were part of the test program... ). Since realism in flight simulation really matters to me, I highly appreciate that approach. If you as a developer tell me that your simulated flight model depicts the turn performance of the real thing, then I accept that this is real physics of course. Your Mustang is by far my favorite aircraft in FSX. Looks like I´ll just have to get used to that it´s right hooves are limping a bit by nature. You can´t beat physics after all.

Thanks and best regards,

Kai

[Lewis - A2A]

Afraid ill have to refer back to Scott for the specifics, I'm just going on second hand reports that I'm aware off. I do think you have found a bug or maybe an issue somewhere so I wouldnt worry too much about digging deep into the difference in reality between the two. But maybe worth it for the general thing though as it makes sense for quicker turn one way than the other.

Anyway let me give Scott a ping.

cheers,
Lewis