Bonanza breakup video analysis, how does it affect Mooney?

[Ragsf15e]

7 hours ago, RescueMunchkin said:

 

Before this thread, I wasn't aware that rolling wings level from an overbanking dive would tend cause a potential over-G condition because of trim, so all of this is great info.

It’s not really rolling the wings level that’s causing the problem as it will also eventually over g if left in the spiral with the same trim setting.  It’s more that the airspeed is rapidly building above what the airplane is trimmed for.  In that condition, it will pull excessive G no matter wings level or banked unless you push forward or change the trim.

[Shadrach]

13 hours ago, Ragsf15e said:

It’s not really rolling the wings level that’s causing the problem as it will also eventually over g if left in the spiral with the same trim setting.  It’s more that the airspeed is rapidly building above what the airplane is trimmed for.  In that condition, it will pull excessive G no matter wings level or banked unless you push forward or change the trim.

True but a roll wings level is a transition from a tight descending turn (descent) to a rapid arrest and/or reversal of said descent (ascent). Both are positive G conditions, but I’m pretty sure that rolling wings level generates a higher load factor than the descending turn…

Wouldn’t the roll to wings level also increase load factor on the ascending wing?

[dkkim73]

Here's a way to look at it: 

In a fast increasing spiral, you are using the generated (large) lift vector to cut a curved path in space laterally and somewhat less so vertically (turning mostly sideways through space). Gravity ("God's gee") is pulling you down as well, but you are cutting sideways. When you roll shiny-side-up, all the lift at that high speed (lots of kinetic energy to use also) all pulls upwards, plus you have 1 g downwards to boot. And the trim setting tries to increase angle of attack further. So all things that will try to bend the wing. 

This "moving in 3 dimensions" and general understanding of curved flight can be positive and useful as well. E.g. emergency descent, you can roll into a 60 degree bank and spend half your lift in a turn while only pulling 2g. The higher wing loading can help you bleed energy and get down faster. 

On another note: 

I just this afternoon after a long week pulled out Rich Stowell's "Emergency Maneuver Training" again after many years. He discusses a wide range of Bad Things and Bad Conditions, focusing a lot on spins but also considering other upsets and Overbanked. But he also expands the Overbanked discussion more broadly to consider overbanked situations down low (e.g. wake turbulence). I don't think I could do the general approach justice, but he brings up pushing (unloading the wing) to allow better roll inputs, as was mentioned above by @Ragsf15e above. 

 

[RescueMunchkin]

13 hours ago, dkkim73 said:

E.g. emergency descent, you can roll into a 60 degree bank and spend half your lift in a turn while only pulling 2g. The higher wing loading can help you bleed energy and get down faster.

 

To get 2g at 60 degree bank, the plane as to be staying a the same altitude...so doesn't that imply that if descending in a 60 degree bank, the plane will be <2g of loading?

[Ragsf15e]

10 minutes ago, RescueMunchkin said:

To get 2g at 60 degree bank, the plane as to be staying a the same altitude...so doesn't that imply that if descending in a 60 degree bank, the plane will be <2g of loading?

True, but @dkkim73 is right about “gods g” (gravity) causing “extra g” on the aircraft when it’s level.  It will still over g in a spiral with just trim, but maybe you can get there quicker by rolling level and pulling…

[dkkim73]

15 minutes ago, RescueMunchkin said:

To get 2g at 60 degree bank, the plane as to be staying a the same altitude...so doesn't that imply that if descending in a 60 degree bank, the plane will be <2g of loading?

Yes, I misspoke about that, you are entirely correct. So it would be less than 2g, though the higher induced drag will help get rid of energy, and if you keep speed up the higher parasitic drag will also help. 

[Ragsf15e]

14 hours ago, Shadrach said:

True but a roll wings level is a transition from a tight descending turn (descent) to a rapid arrest and/or reversal of said descent (ascent). Both are positive G conditions, but I’m pretty sure that rolling wings level generates a higher load factor than the descending turn…

Wouldn’t the roll to wings level also increase load factor on the ascending wing?

Definitely the rolling G would be bad.

[Shadrach]

19 minutes ago, RescueMunchkin said:

To get 2g at 60 degree bank, the plane as to be staying a the same altitude...so doesn't that imply that if descending in a 60 degree bank, the plane will be <2g of loading?

Yes, but in a spiral divergence, the pilot is unlikely to hold a constant bank. Indeed the bank typically increases. At 75°, it takes almost 4gs to hold level flight...so possible to exceed g limits in a descent. It’s easy to imagine a panicked, overloaded and disoriented pilot in a steep bank pulling back on the yoke in an ever increasingly tight turn then catching a glimpse of the sun or the ground and rapidly rolling to wings level without adjusting pitch controls. 

[A64Pilot]

18 hours ago, Shadrach said:

 

Wouldn’t the roll to wings level also increase load factor on the ascending wing?

Yes, many, actually most Crop Dusters have an AD for cracking wing spars, most often it’s the wing opposite to the usual turn direction that cracks because at the end of the spray run most pilots pitch up and turn at the same time, if you pitch up first, then turn it’s surprising how much less stress / fatigue there is on the ascending wing spar. Remember by turning your unloading one wing and adding significant load to the opposite side.

We instrumented an aircraft with strain gauges in a flight test program that extended the wing spar life limit from 23,000 hours to I think it was 40,000 hours so I got to see what maneuvers etc caused the greatest stress.

Older gen aircraft had a wing spar life limit of 5,400 hours as an example.

[Pinecone]

That is what I would expect.

[Hank]

8 hours ago, A64Pilot said:

. . . . if you pitch up first, then turn it’s surprising how much less stress / fatigue there is on the ascending wing spar. Remember by turning your unloading one wing and adding significant load to the opposite side.

Ahh, so that's whymthe CFI insisted on pitching up 15° then rolling in bank when teaching chandelles . . . . Knowing the "why" in addition to the "what" is often beneficial. This would probably never occurred to me without this thread. Thanks, ya'll!

[jetdriven]

A chandelle is a low G maneuver though. Its fixed bank, then constantly increasing bank for the first half. . Then constant pitch and decreasing bank.  Its a requirement of the maneuver.

[Pinecone]

11 hours ago, jetdriven said:

A chandelle is a low G maneuver though. Its fixed bank, then constantly increasing PITCH for the first half. . Then constant pitch and decreasing bank.  Its a requirement of the maneuver.

FTFY

Yes. Pitch then roll is NOT the way they are supposed to be done.

If you roll, stop the roll, then pitch, you are still symmetrically loading the wing.   In a coordinated turn, the lift is the same on both wings.  No matter what one well known You Tuber thinks.

[Hank]

5 hours ago, Pinecone said:

Pitch then roll is NOT the way they are supposed to be done.

If you roll, stop the roll, then pitch, you are still symmetrically loading the wing.   In a coordinated turn, the lift is the same on both wings.  No matter what one well known You Tuber thinks.

"Pitch then Roll" is the methodology my retired Naval Pilot CFII just told me to do chandelles. Now some guy on the interwebs says that's wrong . . . .

Pitch up, then slowly roll through 90° course change, then hold bank and reduce pitch, rolling wings level at original altitude, reverse course and speed near MCA. Pitch up, then roll; later, hold bank and reduce pitch. So I guess its both? 

[Pinecone]

Military and civilian chandelles are not the same.

As @jetdriven said, a civilian chandelle, at least when I learned them, was a roll to 30 degree bank, then pitch.  Maintain 30 degree bank until 90 degrees of turn, then begin to roll out and hold pitch.  You should reach 180 degrees of turn wings level at just above stall speed.

So first half is constant back increasing pitch.  Second half is constant pitch, decreasing bank.

[EricJ]

So I tried this diverging spiral thing in my J model yesterday, a few times.   Trimmed for 100 knots, cranked in 45 degrees of bank and let go.

The first time was to the left, I just let it pitch down a bit and pick up speed, then recovered it.   Wasn't a big deal, limiting the pitch-up rate was kind of a non-event, about as one would expect being at a speed higher than trimmed.

Since that was fairly benign, the second time I just let it go and see what it'd do.   It very slowly started rolling toward level and pitching up on its own (before it got to 160 kts), rolled to the right and pitched back down, kind of the expected phugoid but with some roll.   That time the roll to the right started slowly increasing bank as it was continuing to pitch down, so I recovered it which was not a big deal (in VMC and paying attention to what it was doing).

It seemed like maybe my airplane behaves a little differently doing this to the right than to the left, so I tried initiating one to the right.   It was very slowly increasing roll as it pitched down so I recovered it once it was evident what it was doing.   The roll increase was much slower than what the Bonanza appeared to be doing.

These weren't super-well-controlled experiments, so I wouldn't conclude much based on just these three tries, other than my airplane seems to behave differently depending on the direction.   It was kinda fun, so I'll probably try some more later.   It may be that there's some rigging dependency, which could mean every airplane (well, every Mooney, anyway) may behave a little differently.

[Yetti]

It was a bad several seconds for the Bravo break up.   Slowed down the video.

 

 

[Hyett6420]

On 6/8/2024 at 5:36 PM, dkkim73 said:

This got me thinking about how unusual attitudes come to pass in IMC. The scenarios I can envision at first blush are: 

-autopilot mode confusion (it's not flying the airplane, and the pilot is looking at Foreflight ;))

-autopilot-facilitated trim stall and upset (in any ALT mode other than PIT(ch) and get out of sync on power setting, eg. reducing to descend on intermediate segment, got distracted, etc)

-bad turbulence

-handflying with a paper chart out of nostalgia and got distracted (ok less likely except in failure situation)

 

The Scott Perdue video mentions a "spiral divergence exercise" to get a sense of the natural progression, starting 45 degrees bank from straight-and-level, no trim change, with KIO criteria of 160kts and 60degrees bank. Not clear what speed he starts at.   @PT20J describes an interesting experiment. To the CFI(I)s here: what would be good entry conditions for such an exercise in a Mooney? 

D

Just hand flying then , changing frequencies, or adjusting the routing, ie just taking your eye off the ball for a few seconds can easily get you into the beginnings of loss of control.

[Hank]

On 6/30/2024 at 3:33 PM, Hyett6420 said:

Just hand flying then , changing frequencies, or adjusting the routing, ie just taking your eye off the ball for a few seconds can easily get you into the beginnings of loss of control.

If I do too much at once, or concentrate too long on one thing in IMC, my altitude / heading / attitude begin to drift off of where I want to be. It's hardly loss if control, but staying head down too long could certainly get the plane headed that way.

Do one thing, check the panel; do the next thing, check the panel.

[Hank]

P.S.--good to see you again, Andrew!

@Hyett6420

[Jerry 5TJ]

On 6/8/2024 at 12:36 PM, dkkim73 said:

This got me thinking about how unusual attitudes come to pass in IMC. The scenarios I can envision at first blush are: 

-autopilot mode confusion (it's not flying the airplane, and the pilot is looking at Foreflight ;))

-autopilot-facilitated trim stall and upset (in any ALT mode other than PIT(ch) and get out of sync on power setting, eg. reducing to descend on intermediate segment, got distracted, etc)

-bad turbulence

-…..

A classic failure of the KA256 attitude indicator where over a few minutes the gyro spins down and the artificial horizon data become false: the King AP dutifully follows the AI into a turning spiral. Eventually the AP runs out of trim, kicks itself off and hands control back to the pilot.   The plane is at elevator trim limits, in a high speed spiral descent and the AI shows wings level.   I suspect it is highly confusing — the startled pilot has only seconds to figure it out and apply the correct (no gyro) recovery.  

[Hank]

1 hour ago, Jerry 5TJ said:

A classic failure of the KA256 attitude indicator where over a few minutes the gyro spins down and the artificial horizon data become false: the King AP dutifully follows the AI into a turning spiral. Eventually the AP runs out of trim, kicks itself off and hands control back to the pilot.   The plane is at elevator trim limits, in a high speed spiral descent and the AI shows wings level.   I suspect it is highly confusing — the startled pilot has only seconds to figure it out and apply the correct (no gyro) recovery.  

Didn't Richard Collins write about losing a friend to this? He then went into the simulator to replicate, and failed 3 times out of 4, starting in IMC and expecting the failure. 

[dkkim73]

1 hour ago, Jerry 5TJ said:

A classic failure of the KA256 attitude indicator ...

Yikes. That's terrifying. 

The GFC 700 is still scheming to kill me (favorite ways are mode confusion, FD set too early in HDG mode, and power mgmt on level off). But nothing quite as Gothic as what you describe.

[Mac80]

On 6/7/2024 at 8:23 PM, 201er said:

Scott Perdue describes the recent in flight break up of N47WT. In the video he explains the importance of spiral divergence recovery training and demonstrated some G load math for varying airplanes including Mooney. 
 

Here is a good explanation of spiral divergence: 

https://aerospacenotes.com/flight-dynamics/spiral-divergence/

 

I’m not aware of any in flight break ups of a Mooney. Has it ever happened? Do Mooneys end up a smoking crater intact when they experience spiral dive due to spatial disorientation? 
 

What insight or advice do you have on this topic as it pertains to Mooneys specifically?

 

 

The Mooney Safety Foundation classes discuss and demonstrate entering spiral, spiral recovery, and how to avoid excessive g force by not pulling up to fast and overloading the wings while recovering. 

Picture of Mooney I saw looked like butterfly setting  on the ground.

[Jerry 5TJ]

On 7/1/2024 at 8:01 PM, dkkim73 said:

Yikes. That's terrifying. 

The GFC 700 is still scheming to kill me (favorite ways are mode confusion, FD set too early in HDG mode, and power mgmt on level off). But nothing quite as Gothic as what you describe.

Fortunately, many of those spinning gyro AI have been replaced by solid state AHRS and few of us have only one attitude reference any more.  
But I have flown in a number of Mooney planes with great upgraded glass panels … but the KA256 is still installed over in one corner and remains the sole reference for the autopilot.