Unrecoverable left flat spin

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Stephan
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Unrecoverable left flat spin

Post by Stephan »

Hello,

I wanted to share some difficulties I've faced with the civilian P51 recently.

I used to fly my P51 quite often, taking off, climbing, cruising, and landing without problems. The great GA from A2A kept me away for quite a while so I'm not sure if the P51 has been updated in a way that it makes it harder to fly, or if I'm having a plain old software/hardware bug. Either one of two things happens:

1. At take off, as soon as the aircraft lifts off, it goes into a pretty hard left banking, bad enough so it loses altitude and I'm still too close to the ground and crash.

2. A couple of times I managed to take off by going very easy on the throttle, and applying lots of right aileron and right rudder. But even so I can't maintain level flight for long. The aircraft seems to struggle with power or something, then I get the tell tell signs of stall. Buffeting first then the left wing drops and the plane goes into a very fast left flat spin, that I can't recover from. What's strange is that even with full throttle, no flaps, gear up, about 2 degrees nose up elevator trim, default 6 degrees right rudder trim, the P51 loses speed and enters the left flat spin.

I'm not an expert of the P51, so I'm sure there's something I do wrong, but I can't understand what because like I said I used to fly it regularly without any issues. I also want to mention that I have no similar problems with any of my other A2A aircraft, which are the following:

Aircraft Factory Avro 504k
Aircraft Factory F4U Corsair
Accusim Spitfire
Accusim B17
Accusim B377
Accusim Piper Cub
Accusim Cessna 172
Accusim Cessna 182
Accusim Piper Cherokee
Accusim Piper Comanche

But every aircraft is different so I'd love some guidance on how to fly the P51 properly.
Thanks!
B377 / B-17 / Spitfire / P-51 Civilian / Piper J-3 Cub / C172 / C182 / Cherokee / Comanche / Avro 504k / F4U Corsair / BF109

n421nj
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Re: Unrecoverable left flat spin

Post by n421nj »

What are your trim settings? What is your fuel quantity in each tank?
Andrew

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Stephan
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Joined: 03 Sep 2013, 02:57
Location: Southern California

Re: Unrecoverable left flat spin

Post by Stephan »

n421nj wrote:What are your trim settings? What is your fuel quantity in each tank?
Like I said generally about 2 degrees nose up, 6 degrees right rudder on take off. All tanks half full. I tried many other unusual trim settings but the result is always a strong left bank.
B377 / B-17 / Spitfire / P-51 Civilian / Piper J-3 Cub / C172 / C182 / Cherokee / Comanche / Avro 504k / F4U Corsair / BF109

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Piper_EEWL
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Re: Unrecoverable left flat spin

Post by Piper_EEWL »

Just to ask the regular questions: Are you all up to date? Does the maintenance hangar report any issues?

I've not been flying the Mustang a lot lately but last week I took it for a spin and it performed just fine.
B377&COTS, J3 Cub, B-17G, Spitfire, P-40, P-51D, C172, C182, Pa28, Pa24, T-6 Texan, L-049&COTS, Bonanza V35B

Stephan
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Posts: 67
Joined: 03 Sep 2013, 02:57
Location: Southern California

Re: Unrecoverable left flat spin

Post by Stephan »

Piper_EEWL wrote:Just to ask the regular questions: Are you all up to date? Does the maintenance hangar report any issues?

I've not been flying the Mustang a lot lately but last week I took it for a spin and it performed just fine.
I have the latest accusim update. I ran it one more time and it said my P51 was up to date, didn't perform any update. The hangar says like new. I did a complete overhaul after each crash.
B377 / B-17 / Spitfire / P-51 Civilian / Piper J-3 Cub / C172 / C182 / Cherokee / Comanche / Avro 504k / F4U Corsair / BF109

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Piper_EEWL
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Re: Unrecoverable left flat spin

Post by Piper_EEWL »

Ok. The next step I would try is to remove the .dat file of the P-51. Back up your current file and have Accusim create a new one (happens automatically when the simulation is loaded).
B377&COTS, J3 Cub, B-17G, Spitfire, P-40, P-51D, C172, C182, Pa28, Pa24, T-6 Texan, L-049&COTS, Bonanza V35B

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Lewis - A2A
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Re: Unrecoverable left flat spin

Post by Lewis - A2A »

You can also force an update by deleting the update folder in here for your Mustang; \FSX\A2A\P51civ

Then when you run the updater it will update everything for you.

thanks,
Lewis
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Stephan
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Location: Southern California

Re: Unrecoverable left flat spin

Post by Stephan »

Lewis - A2A wrote:You can also force an update by deleting the update folder in here for your Mustang; \FSX\A2A\P51civ

Then when you run the updater it will update everything for you.

thanks,
Lewis
Good idea, I'll try that tonight and I'll let you know if I see any change. Thank you.
B377 / B-17 / Spitfire / P-51 Civilian / Piper J-3 Cub / C172 / C182 / Cherokee / Comanche / Avro 504k / F4U Corsair / BF109

n421nj
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Re: Unrecoverable left flat spin

Post by n421nj »

So did it work?
Andrew

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DHenriques_
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Re: Unrecoverable left flat spin

Post by DHenriques_ »

Stephan wrote:Hello,

I wanted to share some difficulties I've faced with the civilian P51 recently.

I used to fly my P51 quite often, taking off, climbing, cruising, and landing without problems. The great GA from A2A kept me away for quite a while so I'm not sure if the P51 has been updated in a way that it makes it harder to fly, or if I'm having a plain old software/hardware bug. Either one of two things happens:

1. At take off, as soon as the aircraft lifts off, it goes into a pretty hard left banking, bad enough so it loses altitude and I'm still too close to the ground and crash.

2. A couple of times I managed to take off by going very easy on the throttle, and applying lots of right aileron and right rudder. But even so I can't maintain level flight for long. The aircraft seems to struggle with power or something, then I get the tell tell signs of stall. Buffeting first then the left wing drops and the plane goes into a very fast left flat spin, that I can't recover from. What's strange is that even with full throttle, no flaps, gear up, about 2 degrees nose up elevator trim, default 6 degrees right rudder trim, the P51 loses speed and enters the left flat spin.

I'm not an expert of the P51, so I'm sure there's something I do wrong, but I can't understand what because like I said I used to fly it regularly without any issues. I also want to mention that I have no similar problems with any of my other A2A aircraft, which are the following:

Aircraft Factory Avro 504k
Aircraft Factory F4U Corsair
Accusim Spitfire
Accusim B17
Accusim B377
Accusim Piper Cub
Accusim Cessna 172
Accusim Cessna 182
Accusim Piper Cherokee
Accusim Piper Comanche

But every aircraft is different so I'd love some guidance on how to fly the P51 properly.
Thanks!
Have you checked outside to see if the flaps are up and equal? What you are describing is almost exactly what you could expect if taking off with the flaps deployed even partially asymmetrically.
Other than that or improper control usage (which from your post seems ok) you might have a controller issue or some problem with the installation. But if this is the ONLY issue you are having I wouldn't suspect the installation.
Dudley Henriques

Stephan
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Posts: 67
Joined: 03 Sep 2013, 02:57
Location: Southern California

Re: Unrecoverable left flat spin

Post by Stephan »

I just wanted to reopen this post since I could never fix the issue but someone just posted the same problem so I figured it may be relevant. Sorry for the double post.
Here's what I tried:

I delete all p51 civ files
I install the p51 civ again
I install the p51 civ accusim again

Everything works. I can fly the aircraft without problems. No more left wing drop. There's still the usual torque you have to control to stay on the runway but nothing I'm not used to from my dozens of take offs.

Now I install the latest accusim update

The p51 acts up again. Same sharp left wing drop on take off. I can't take off with the plane anymore.
Sometimes I'm able to take off but then after a few seconds of level fly the left wing drops suddenly without me doing anything and the aircraft enters in a fast spin. If I don't touch anything the spin slowly recovers by itself and then starts again, until I crash.

So in my case it looks like something has been introduced in the p51 accusim update at some point that creates that behavior. I don't know if it's the same for everyone and maybe it's considered more realistic behavior and I don't know what to do, or maybe it's a bug that appears on certain configurations. I'm at a loss.
All I can say is that once updated It makes the aircraft impossible to fly for me. I've reverted to my original non updated one in the meantime, but it's a shame because I can't benefit from the recent updates like the possibility of using a third party gps.
Any help would be really appreciated.
B377 / B-17 / Spitfire / P-51 Civilian / Piper J-3 Cub / C172 / C182 / Cherokee / Comanche / Avro 504k / F4U Corsair / BF109

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Lewis - A2A
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Re: Unrecoverable left flat spin

Post by Lewis - A2A »

Hello,

did you ever try the last thing we suggested?

Also have you checked the sim settings are still set as needed in the manual, and also that the fuel in the payload panel is ok?

thanks,
Lewis
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Stephan
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Posts: 67
Joined: 03 Sep 2013, 02:57
Location: Southern California

Re: Unrecoverable left flat spin

Post by Stephan »

Yes, I deleted all folders when reinstalling. Fuel panels are ok, flaps are up on both sides.
I think I want to stress that with the same configuration and settings, the p51 works as I expect on a clean install, but displays that behavior right after I apply the latest accusim update, with the same FSX settings, all new plane, cold and dark, same airport and time and weather conditions.
I know the update has worked because after I update I have access to the third party gps. It's actually the update that causes this.
And by that, Lewis, I don't mean that the update has a bug, but simply that the behavior of the aircraft is so different that in one case I have 100% successful take offs and in the other about 80% crashes.
B377 / B-17 / Spitfire / P-51 Civilian / Piper J-3 Cub / C172 / C182 / Cherokee / Comanche / Avro 504k / F4U Corsair / BF109

Stephan
Airman First Class
Posts: 67
Joined: 03 Sep 2013, 02:57
Location: Southern California

Re: Unrecoverable left flat spin

Post by Stephan »

Lewis - A2A wrote:Hello,

did you ever try the last thing we suggested?

Also have you checked the sim settings are still set as needed in the manual, and also that the fuel in the payload panel is ok?

thanks,
Lewis
Hey Lewis, I gave as much information as I could about the situation to someone else who tried to help on another thread, so I figured I should repeat that here for you, with screenshots if that helps:

First of all, to get this out of the way, here's me flying level a few minutes ago without problems, and then some screenshots of my successful landing. That was done with a clean install of the P51, no Accu sim update. As usual everything went fine, from take off to cruising to landing.

https://www.dropbox.com/s/c6gfcs9lm9zq7 ... k.jpg?dl=0

Now the answer to your questions.

Now all the following images show the aircraft on the same airport, same time, same conditions, after the latest accu sim update applied.

First of all a comparison of the view from inside the cockpit. On the left before the update, on the right after. You can see that the top of the canopy is not perfectly horizontal anymore. I don't know if that means anything but that's already a difference.

https://www.dropbox.com/s/y81i0s8cq1y57 ... t.jpg?dl=0

Yes I delete all folders before applying the update

I started cold and dark, then did the full check list, started the engine, warmed up. This is what I have:

46 gallons in each wing
pilot's weight 146 lbs
total payload 630 lbs
Brand new oil and coolant, garage shows no problems.
Oil temp 49

https://www.dropbox.com/s/ebfg3lp3sb8sc ... l.jpg?dl=0

My controls are not locked, as showing on the following picture. All my trims work, but I don't touch anything during take off anyway.
Here are the following trim tabs, which I have left at what you get by default on cold and dark. I believe:
Rudder : 6.1 right
elevator : 0
Aileron : 0
Flaps are up

https://www.dropbox.com/s/31izo7to9y7ll ... p.jpg?dl=0

Here's another image showing a test of the control surfaces from the outside. Everything works, flaps are up on both sides:

https://www.dropbox.com/s/oktf8l5wtg6hy ... t.jpg?dl=0

I managed to keep control of the aircraft at take off this time but as usual at a few hundred feet, while as I was flying level gear up, no flaps, throttle about 80%, not touching the controls, the left wing started to drop and I entered a fast spin. I captured the outside view. The ailerons seem fine, leveled. I tried to apply right aileron to counter the spin but it was like the aileron had no authority anymore, and I crashed. My feeling is that the left wing drop ALWAYS happens, regardless of what I do, sometimes very early, and that's why I can't even take off, sometimes after a minute airborne or so. So I think the problem has nothing to do with take off, it's more like a systematic behavior of the aircraft that I can't explain.

https://www.dropbox.com/s/upfo2elvo8agz ... n.jpg?dl=0
B377 / B-17 / Spitfire / P-51 Civilian / Piper J-3 Cub / C172 / C182 / Cherokee / Comanche / Avro 504k / F4U Corsair / BF109

Stephan
Airman First Class
Posts: 67
Joined: 03 Sep 2013, 02:57
Location: Southern California

Re: Unrecoverable left flat spin

Post by Stephan »

Hi Lewis,

Adding my latest experiment in the hope of getting support...
As soon as I took off, I activated the AP to force the aircraft level, raised the gear, and guess what happened about 40 seconds in? The left wing dropped and the aircraft entered a wild spin, with the AP ROLL ON and without me touching any of the controls!
I paused, went into outside view. All control surfaces were level, while the aircraft was belly over. I rolled over all trim tabs and they were all on the preflight settings, untouched. Manifold pressure was okay, rpm, oil pressure all in the green and the engine was purring like a kitten during the spin.
If you can explain that, it would be hugely appreciated! I tried everything I could think of, and this makes no sense to me.
B377 / B-17 / Spitfire / P-51 Civilian / Piper J-3 Cub / C172 / C182 / Cherokee / Comanche / Avro 504k / F4U Corsair / BF109

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