Change in spin behavior

[EnDSchultz]

So I was trying some spins recoveries recently and they don't feel quite right. All spins were done to the left. I remember in early versions of the 172 (and seeing some first impressions videos confirm this) that the response to spinning and subsequent recovery was spot on. The entry into the spin was quite regular and it stabilized very quickly. In recovery, full opposite rudder, and elevator neutral or forward resulted in immediate stop to the rotation and return to controlled flight.

Now, the entry feels less predictable; occasionally at the end of the first turn I'll even see the nose come above the horizon (approximately wings level) if I leave even a little power in. In recovery, opposite rudder and elevator forward produces a very sloppy, delayed response. When the rotation stops, it's punctuated by a -dramatic- yaw to the left (the direction of the spin) before the nose straightens out.

I've made sure weight was within utility category tolerances and two passengers in the front seats (student/instructor) to try and match videos I've seen of spin recoveries, but it's just not as crisp as the real thing, nor as I recall it being when the Accusim 172 was released.

Would someone care to try out a few spins and see if I'm just doing it all wrong?

[EnDSchultz]

Now, I really feel like a dork and HATE to be "that guy" who bumps his own thread when nobody responds, but I figured it'd be pretty important to take note if a recent change to the flight model (I suspect the changes to low speed flight in 2.0) adversely affected something as vital to training as stall characteristics.

[taildraggin68]

I haven't tried a spin yet, got wrapped in other stuff will give her a spin or two in the morning see what shakes loose

[computerflyer]

I recently tried out the A2A C172 for the first time and was doing some power-off stalls (with latest update, only pilot onboard). The stalls seemed perfectly normal and easily recoverable by neutralizing the elevator. This is what I expected based on the C172's reputation as a very benign, stable flyer. Then I tried another stall, but instead of neutralizing the elevator, I continued to hold full up elevator. I expected the C172 to behave the same as some other GA planes, to mush along with a high sink rate, with bank controllable with rudder.

I was quite surprised when the plane suddenly dropped the right wing and went into a spin or spiral dive, I'm not sure which. I quickly neutralized the elevator and applied full opposite rudder. The rotation did not stop immediately, taking maybe a turn to stop. At that point the C172 was in a steep dive and approaching red line on the airspeed indicator. I didn't notice any odd yawing during the recovery. After pulling out of the dive as gently as possible in order to keep the wings attached, I realized that I'd lost a couple thousand feet of altitude - and I'd started out at only 3,000 feet. So much for the idea of benign flight behavior!

[Oracle427]

The description that computerflyer just gave of a 172 held in a stall with full back elevator very much describes the C172 I know. You will need to use very prompt and very precise footwork on the rudder pedals to prevent the aircraft from entering a spin or going into a spiral dive.

From what you described it sounds like you entered an incipient spin and quickly got out of it and entered a spiral dive. This has happened to me during training in a 172 and it happens VERY FAST. The G forces ramp up very quickly.

I haven't tried this in a while in the A2A 172. Let's see what it is like.

[Scott - A2A]

We haven't made any changes to the 172 spin characteristics in quite a long time. Just to check, I tried one and it entered smoothly and after about 2 turn, full rudder broke it in about 1/2 turn. If you just release the controls, the spin should slowly come out.

Make sure, btw, you are not spinning with power or with passengers in the back seat.

Also, make sure you have your realism settings on realistic.

Scott.

[DHenriques_]

So I was trying some spins recoveries recently and they don't feel quite right. All spins were done to the left. I remember in early versions of the 172 (and seeing some first impressions videos confirm this) that the response to spinning and subsequent recovery was spot on. The entry into the spin was quite regular and it stabilized very quickly. In recovery, full opposite rudder, and elevator neutral or forward resulted in immediate stop to the rotation and return to controlled flight.

Now, the entry feels less predictable; occasionally at the end of the first turn I'll even see the nose come above the horizon (approximately wings level) if I leave even a little power in. In recovery, opposite rudder and elevator forward produces a very sloppy, delayed response. When the rotation stops, it's punctuated by a -dramatic- yaw to the left (the direction of the spin) before the nose straightens out.

I've made sure weight was within utility category tolerances and two passengers in the front seats (student/instructor) to try and match videos I've seen of spin recoveries, but it's just not as crisp as the real thing, nor as I recall it being when the Accusim 172 was released.

Would someone care to try out a few spins and see if I'm just doing it all wrong?

We did our spin tests configuring the 172 as required for the real airplane; in the utility category envelope.
This means doing a weight and balance before you fly as to useful load. You will probably have to adjust fuel load as well to meet the cg requirement for the utility envelope.
Make sure you are within this utility envelope before attempting spins.
Configured within the utility envelope you should get normal spin behavior from the 172.
Dudley Henriques

[EnDSchultz]

I do have my realism sliders all on max and yes, I made sure my weight and balance conforms to the utility category, as I said in my initial post. With two 170lb passengers in the front seats, no rear passengers, no baggage, and 10 gallons of fuel in each wing, that gave me just around 2100lbs with an arm about 39 inches. Comfortably within the utility category per the POH.

Here are a few examples, which I selected for their similar conditions. All entered in a nose-high attitude, all left power on to exaggerate the rotation, and all let the spin stabilize before recovering:

http://youtu.be/MIjmMi7XN4M?t=1m30s -- Absolutely no question when he put in recovery inputs on the control surfaces. Didn't even need to idle the power. The spin stops cleanly and immediately, and he's able to pull out of the dive at once.

http://youtu.be/jrSdUCfvkT4?t=9m40s -- Here's the flight model as it was shortly after release. Again, power on. A little yawing wobble in the nose when he recovers. Seen this occasionally on videos of actual spins.

http://youtu.be/LlWBB0wholE -- Now here's my experience. Mine is the only case where the nose comes ABOVE the horizon in that first turn. Full back pressure and full left rudder is held; when you hear me cut power at 0:10 seconds I immediately apply full right rudder and slightly forward on the yoke (I have control sensitivities on max for this test so the inputs are instantaneous). It takes about two whole seconds before the plane is in stable flight and I can pull out of the dive... What on earth is that huge lurch to the left at 0:11 when the rotation stops?

Maybe I'm just splitting hairs...

[DHenriques_]

I do have my realism sliders all on max and yes, I made sure my weight and balance conforms to the utility category, as I said in my initial post. With two 170lb passengers in the front seats, no rear passengers, no baggage, and 10 gallons of fuel in each wing, that gave me just around 2100lbs with an arm about 39 inches. Comfortably within the utility category per the POH.

Here are a few examples, which I selected for their similar conditions. All entered in a nose-high attitude, all left power on to exaggerate the rotation, and all let the spin stabilize before recovering:

http://youtu.be/MIjmMi7XN4M?t=1m30s -- Absolutely no question when he put in recovery inputs on the control surfaces. Didn't even need to idle the power. The spin stops cleanly and immediately, and he's able to pull out of the dive at once.

http://youtu.be/jrSdUCfvkT4?t=9m40s -- Here's the flight model as it was shortly after release. Again, power on. A little yawing wobble in the nose when he recovers. Seen this occasionally on videos of actual spins.

http://youtu.be/LlWBB0wholE -- Now here's my experience. Mine is the only case where the nose comes ABOVE the horizon in that first turn. Full back pressure and full left rudder is held; when you hear me cut power at 0:10 seconds I immediately apply full right rudder and slightly forward on the yoke (I have control sensitivities on max for this test so the inputs are instantaneous). It takes about two whole seconds before the plane is in stable flight and I can pull out of the dive... What on earth is that huge lurch to the left at 0:11 when the rotation stops?

Maybe I'm just splitting hairs...

From what I'm seeing it's not that far off really. Your nose does come up to the horizon in the first turn but that could be any number of things causing it, including your controller settings. The spin dynamics in the FDE are extremely complex and what I've found in testing is that no two spins are exactly alike; close but not exactly alike.
One thing; power can be used to augment the entry along with just a bit of accelerated stall so that the stall break is more pronounced but the power should be pulled within the first quarter turn.
All in all, doesn't look all that bad.
DH

[EnDSchultz]

From what I'm seeing it's not that far off really. Your nose does come up to the horizon in the first turn but that could be any number of things causing it, including your controller settings. The spin dynamics in the FDE are extremely complex and what I've found in testing is that no two spins are exactly alike; close but not exactly alike.
One thing; power can be used to augment the entry along with just a bit of accelerated stall so that the stall break is more pronounced but the power should be pulled within the first quarter turn.
All in all, doesn't look all that bad.
DH

I've done probably a dozen, and looked at a similar number of real world spins, even done by students. The response I get to recovery inputs in the sim always looks...lazy, wallowing, and delayed compared to what I see in the vids, which always looked very sharp and instantaneous. And I got the distinct impression it wasn't always like that, since I've owned the A2A 172 from about 1.5 onward. My hypothesis was that the slow flight "vortex simulation" added in 2.0 might have inadvertently affected stall/spin characteristics somehow. Maybe my memory just sucks.

Eventually I'll get around to the point in my training where I have to do spins in a real 172, and then I'll put this to bed for good. And I suppose in the end I'm being a too picky. A2A planes still spin better than anything else in FSX, that's for damn sure. I'm just a stickler for perfection! Thanks for putting up with me.

[DHenriques_]

From what I'm seeing it's not that far off really. Your nose does come up to the horizon in the first turn but that could be any number of things causing it, including your controller settings. The spin dynamics in the FDE are extremely complex and what I've found in testing is that no two spins are exactly alike; close but not exactly alike.
One thing; power can be used to augment the entry along with just a bit of accelerated stall so that the stall break is more pronounced but the power should be pulled within the first quarter turn.
All in all, doesn't look all that bad.
DH

I've done probably a dozen, and looked at a similar number of real world spins, even done by students. The response I get to recovery inputs in the sim always looks...lazy, wallowing, and delayed compared to what I see in the vids, which always looked very sharp and instantaneous. And I got the distinct impression it wasn't always like that, since I've owned the A2A 172 from about 1.5 onward. My hypothesis was that the slow flight "vortex simulation" added in 2.0 might have inadvertently affected stall/spin characteristics somehow. Maybe my memory just sucks.

Eventually I'll get around to the point in my training where I have to do spins in a real 172, and then I'll put this to bed for good. And I suppose in the end I'm being a too picky. A2A planes still spin better than anything else in FSX, that's for damn sure. I'm just a stickler for perfection! Thanks for putting up with me.

No problem. I've spent a lifetime seeking perfection in the air. Not sure if I ever made it although I think I got close once or twice.
Anyway, I got through it alive if that means anything )
DH