Turbulence.

[M016576]

After a sustained bumpy (continuous mod) flight for about an hour on Friday, I started to ask myself... how much turbulence is too much for a Mooney?

 The obvious answer being “well, when the wings buckle And the tail breaks off.”

but is there some other method, less subjective than “this feels to be about moderate” that one uses to determine if it’s “too much?”  and one needs to then slow to maneuvering speed?

[Jerry 5TJ]

It’s a case of “how lucky do you feel?” in that the ultimate load depends on the vertical gust you encounter.  

This is a version of the familiar gust / maneuver graph. It shows the loading curves from several different gust velocities.  

If you think you may encounter a 50 FPS vertical gust you’d better be close to your Va.  And have your seat belts cinched down.  

 

[carusoam]

It definitely deserves a quick review when anything becomes airborne, like the iPad Or kneebord....

By the time things are bouncing off the ceiling.... you want to be slowed already...

Flying near thunderstorms can leave you Close to vertical up and or downdrafts...

These themselves are not the reasons to slow down...  But they are the hint that some other big things are quite possibly in the neighborhood worth preparing for.

A g-meter would be helpful at defining the type of turbulence you are experiencing... but it isn't forward looking enough to tell windshear is in front of you....

Clear air turbulence, Lee side of mountains on windy days....

I don’t have a lot of experience in this area so I stay very conservative.  I have broken aluminum pieces in a lab environment, studying stress and strain, if that helps... there are three levels...

• stress can bend metal and have it unbend. Ordinary in bumpy flight activity.
• Strain is the metal stretching beyond its ability to bend back on its own. Beyond the limit of ordinary and may be difficult to bring the plane home...
• Yielding is the point the metal has failed. The strength or shape of the wing may not support flight...

There is some 'magic' knowing.... staying below maneuvering speed will protect the plane from breaking, by stalling before reaching reaching the yield strength of the spars... But, who wants to be in turbulence stalling a plane? 

PP thoughts only, not a CFI...

Best regards,

-a-

[Marauder]

It’s a case of “how lucky do you feel?” in that the ultimate load depends on the vertical gust you encounter.  

This is a version of the familiar gust / maneuver graph. It shows the loading curves from several different gust velocities.  
If you think you may encounter a 50 FPS vertical gust you’d better be close to your Va.  And have your seat belts cinched down.  
 

To put that rate in perspective, it means going from straight and level to 3,000 FPM. Wonder how the Mooney stacks up to other planes.


Sent from my iPhone using Tapatalk Pro

[carusoam]

Stacking up to other planes...

We have an app for that...

The accident report search program that somebody demonstrated the other day, may be helpful to shed some light...

Very few Mooneys have been broken in flight.  I remember one being bent and landing successfully....

When it comes to inflight break-ups, there is one model of plane that really stood out in the history of human flight... with the most recent event occurring after a vacuum failure above IMC, and the flight descending into IMC...

PP observations only, not a statistician or accident investigator....

As far as numbers on the chart... 66fps is the same as 45mph.  5000fpm 57mph.   (Check my math, Alexa did my calcs...) I Highlighted the m and s.  A 5,000 fpm up or downdraft is thunderstorm type activity... (one is stronger than the other, neither would be good...)

Being in IMC and seeing lightening flashes in the clouds? Expect the iPad to be up around the ceiling.... and some weather avoidance hardware purchased on the following Monday...

Best regards,

-a-

[Hank]

1 hour ago, Jerry 5TJ said:

It’s a case of “how lucky do you feel?” in that the ultimate load depends on the vertical gust you encounter.  

This is a version of the familiar gust / maneuver graph. It shows the loading curves from several different gust velocities.  

If you think you may encounter a 50 FPS vertical gust you’d better be close to your Va.  And have your seat belts cinched down.  

 

Yep, 50 fps is 3000 feet per minute on the VSI; 66 fps is durn near 4000 fpm, whuch my VSI won't register.

I do recall reading once about a Mooney that hit bad turbulence and landed somewhere in IL? with a bunch of popped rivets and a bent wing. The plane (Bravo?) was totalled, but landed normally with no injuries. That being said, I've only slowed to Va for turbulence once, a clear day in Wyoming about the time ATC said I would hit it, and during the period when I was off radar coverage at 8500 msl heading from western SD to Billings, MT. Slow down, cinch the belts and motor on . . . . slower.

P.S.--that's one time in over 10 years and 700+ hours, trqveling from Yellowstone to Niagara to Ft Lauderdale, lots of time over and through the Appalachians. Fly safe!

Edited February 4, 2018 by Hank

[Piloto]

It is not only the airframe that gets affected by turbulence but items attached to it such as alternators, heavy avionics, seat mechanism and others. Heavy concentrated cargo such as batteries, motors and others can bend the baggage floor if not properly secured. Best is to avoid turbulence environment if not slow down to 110kts or less and ride the waves. If unable to out climb the build up I just go down (terrain permitting) to 1,000ft or less. Vertical downdrafts can not go through ground so they slow down closer to the ground. Be on the look out for a microburst condition when IAS suddenly changes, although small planes are less affected. When in turbulence I tighten my seatbelt as much I can. This eliminates the sudden 0g jolts that can bump your head with the ceiling and make you feel uncomfortable. I found the Stormscope to be useful in avoiding turbulence conditions. Where there are dots there is turbulence, but where there is not dots there could be turbulence.

José

[Guest]

Do airframes soaked with WD-40 handle turbulence better?

Sorry, I couldn’t resist!

Clarence

Edited February 5, 2018 by M20Doc

[N201MKTurbo]

I've been in turbulence before with the Mooney where maintaining any particular airspeed was impossible The only thing I could do was try to keep the wings and nose as level as possible. When the VSI was pegged at the top reduce power to idle when it was pegged at the bottom give her all she's got. How the wings, tail and engine stayed in one piece is beyond my comprehension. Even with the seat belt as tight as I could get it I was still banging my head on things rather severely.  

After this incident I inspected the plane and didn't find any damage. I wish I could say the same for me. I still get cold sweats flying in bumps.

This incident happened very near where Steve Fossett crashed. Perhaps from the same kind of conditions.

[Bob_Belville]

3 hours ago, carusoam said:

 

Being in IMC and seeing lightening flashes in the clouds? Expect the iPad to be up around the ceiling.... and some weather avoidance hardware purchased on the following Monday...

Well, it was pre-iPad days but otherwise BTDTHTTS.

[Piloto]

6 hours ago, M20Doc said:

Do airfrmaes soaked with WD-40 handle turbulence better?

Sorry, I couldn’t resist!

Clarence

Don't know about WD-40 for turbulence but for sure the piss tube will keep you from getting soaked in turbulence.

[jetdriven]

10 hours ago, Marauder said:

 

To put that rate in perspective, it means going from straight and level to 3,000 FPM. Wonder how the Mooney stacks up to other planes.


Sent from my iPhone using Tapatalk Pro

 

There was an M20K offered for salvage. It encountered mountain wave activity and it sustained an estimated + and -10G in rapid succession. The pilot continued on but noticed it wasn’t flying right and landed. The wings were bent up and the fuselage was bent down. The wings were like bent up 18” at the tips and the fuselage was banana shaped.   You could stick your thumb through the gap between the fuselage and the back of the baggage door.  

Bottom line, the M20 series Along with the 172 and 182 are basically, statistically unbreakable airplanes. Respect the limitations......but don’t worry about airframe failure. Worry about something else. 

Edited February 5, 2018 by jetdriven

[jetdriven]

10 hours ago, Marauder said:

 

To put that rate in perspective, it means going from straight and level to 3,000 FPM. Wonder how the Mooney stacks up to other planes.


Sent from my iPhone using Tapatalk Pro

 

The certification standard is also “instantaneous” change to 50 fps. Another thing,  Va is related to a single full control deflection and release input while the 25/50 or 30/60 FPS gust loading is related to green arc and yellow arc. Different conditions and different causes, different airspeed limits. 

[M016576]

Thanks all.  I seem to spend more time in turbulence in the Mooney than in the jet- and it also tends to feel more “intense”- might be the wing shape, or the seatbelt vs a four piece harness, or maybe it’s just in my mind.  It’s nice to have some more objective metrics to help sanity check a good course of action.

ive seen that chart before- but I’ve found it of little use operationally.  The static system lags so much that you can’t really tell what sort of burst you just hit (50fps? 75? 25?). I like the idea of “if you’re iPad hits the ceiling...”. And of course it’s one thing to ride a wave up and down (which is basically no additional loading), it’s another thing entirely to be in the continuous bumps.  

Thanks!

[jaylw314]

3 minutes ago, M016576 said:

Thanks all.  I seem to spend more time in turbulence in the Mooney than in the jet- and it also tends to feel more “intense”- might be the wing shape, or the seatbelt vs a four piece harness, or maybe it’s just in my mind.  It’s nice to have some more objective metrics to help sanity check a good course of action.

ive seen that chart before- but I’ve found it of little use operationally.  The static system lags so much that you can’t really tell what sort of burst you just hit (50fps? 75? 25?). I like the idea of “if you’re iPad hits the ceiling...”. And of course it’s one thing to ride a wave up and down (which is basically no additional loading), it’s another thing entirely to be in the continuous bumps.  

Thanks!

I guess that's the tricky part--what does an instantaneous 50 fps gust FEEL like?  I suspect it is far worse than just "iPad hits the ceiling."  It might feel more like a "eyeballs hitting the ceiling" or "lots of poo coming out" kind of bump.

It'd be nice to know how an instant 50 fps gust compares to the FAA standard definitions of turbulence

[carusoam]

Different ways to look at it...

1) 66fps was 45mph...instantly accelerating up or down to 45mph... think of it like a kid throwing a baseball...

2) Only this time, king kong is throwing your airplane.

3) Your baseball kid throwing your iPad... full wind-up, for a trained 12 year old.... Probably make you a bit upset...

4) less subtly, a 45mph crash into.... a wall of air.... hmmmmm?  Defining what a wall of air feels like when you crash into it isn't going to work.   Will it...?    Dropping the plane onto an airbag... interesting thought....

So, bouncing your iPad off the ceiling is the hint that turbulence has gotten very strong, before you get to spar testing mode...

Unfortunately there isn't a way to see the big bump and know the next one won’t be even bigger...

Trying to to help think this through...,

-a-

 

 

[donkaye, MCFI]

15 hours ago, M016576 said:

After a sustained bumpy (continuous mod) flight for about an hour on Friday, I started to ask myself... how much turbulence is too much for a Mooney?

 The obvious answer being “well, when the wings buckle And the tail breaks off.”

but is there some other method, less subjective than “this feels to be about moderate” that one uses to determine if it’s “too much?”  and one needs to then slow to maneuvering speed?

I've been told by some working at Mooney that the wing has been stress tested to a positive 9.5 G.  At that point the jig broke.  Unless you end up in a thunderstorm, it is unlikely the plane will break apart before you do.

Having said that, why would you even want to put yourself in a turbulence situation?  A 2,500 - 3368 pound airplane is no match for very serious convective weather.  It is not difficult to become familiar enough with weather phenomenon to know when it is safe to go or not go; when to expect turbulence and when not to.  Why would you even consider putting yourself or your passengers in such uncomfortable situations that they might never want to get into an airplane again?

My advice would be to learn the weather well enough to stay on the ground during expected turbulent conditions.  With experience you will rarely be wrong, and as the old say goes, "You'd rather be on the ground wishing you were in the air, that in the air wishing you were on the ground."

If you choose not to take my advice, then I've attached an article I wrote several years ago discussing ways to mitigate the effects of turbulence.

On Flying Turbulence.pdf

[M016576]

1 hour ago, donkaye said:

Having said that, why would you even want to put yourself in a turbulence situation?  A 2,500 - 3368 pound airplane is no match for very serious convective weather.  It is not difficult to become familiar enough with weather phenomenon to know when it is safe to go or not go; when to expect turbulence and when not to.  Why would you even consider putting yourself or your passengers in such uncomfortable situations that they might never want to get into an airplane again?

My advice would be to learn the weather well enough to stay on the ground during expected turbulent conditions.  With experience you will rarely be wrong, and as the old say goes, "You'd rather be on the ground wishing you were in the air, that in the air wishing you were on the ground."

Where I live, light turbulence, and at times moderate turbulence are a part of flying during certain parts of the year- due to winds and the mountains that surround the local area.  I am quite familiar with the products available for forecasting and predicting possible turbulence, and the weather patterns that tend to bring it. I’m also familiar enough to know that if forecasted severe turbulence is out there, or an active convective sigmet, I shouldn’t be going flying. So you’re right: it’s not difficult to know when to not go from a planning standpoint. 

 The reason I ask the question, is not to go traipsing through known convective buildups, but more due to unforecast, or changing conditions creating a more serious situation than was forecast during preflight planning and identifying that situation correctly.  And I’m curious what other pilots use as their benchmark.

This is the way I took your response, but using icing as the subject, vice turbulence, to illustrate the way your response reads to me.   if this is not what you intended please let me know:  Think of my question as being more like “how can I tell if the icing is more serious than moderate as I’m punching through a layer in my FIKI TKS Bravo”, and your response being “don’t go flying if there is any chance of icing.”  I would say that your advice is conservative in nature (don’t go flying if their is a chance of turbulence), but not all that practical, or realistic.  Or did you just mean a chance of moderate turbulence (an airmet issued, maybe?). Still, that seems a bit conservative.

edit: I read your paper on your experience in the ovation on turbulence. How does putting the gear down and deploying the spoilers aerodynamically “help” with the turbulence?  Is the ride markedly different than just flying the aircraft below gear deployment speed (125ish knots? So just below maneuvering speed). I’ve never heard of this technique before, is this a common thing in light GA planes?  it seems inefficient, but if it helps the ride dampened out maybe worth it?

Edited February 5, 2018 by M016576

[Yetti]

1 Mooney have sustained airframe damage that fell them out of the sky according to the NTSB.    That guy that flew into the thunderstorm.  The other one was the K that was mentioned.    

As far as strapping down.  My head is really close to the ceiling.   so first bump my seatbelt gets uncomfortable tight and I will slow down.

[bradp]

I’m more concerned about accessories being damaged than the airframe itself.  Respect the concept of V-a and load factor.  Understand that things not designed to the same ultimate load factor may break and cause additional problems (my anecdote is having sheared the vacuum pump rotor in turbulence... it was probably on its way out ... but it can happen.  I was in VMC but IMC would have been an absolute emergency).  

[Jerry Pressley]

The K that you mentioned supposedly pulled out so hard that it crushed the pilots seat. We picked that one up and the seat back for the rh seat was missing.  also the bottom was not articulating.  Someone stole a good rh articulating seat and replaced with an odd seat bottom.  The left seat was still there and in perfect condition.  Remember the arm rests making it impossible to move the rh into the lh position?  Also when we picked it up it had already been signed off as airworthy.  There were small wrinkles on each wing inboard from stress.  We drilled the rivets on both sides of the wrinkles and they went away.  FAA wouldn't accept that until approved by the Mooney factory.  Their big concern was not with the wrinkles but the possibility that the retract rods had stretched.  After measuring the rods all was approved to return to service.  We kept it for some time flying a lot and passed it on with all in the logs and it is still out there less articulating on rh side.  Jerry P

[donkaye, MCFI]

7 hours ago, M016576 said:

Where I live, light turbulence, and at times moderate turbulence are a part of flying during certain parts of the year- due to winds and the mountains that surround the local area.  I am quite familiar with the products available for forecasting and predicting possible turbulence, and the weather patterns that tend to bring it. I’m also familiar enough to know that if forecasted severe turbulence is out there, or an active convective sigmet, I shouldn’t be going flying. So you’re right: it’s not difficult to know when to not go from a planning standpoint. 

 The reason I ask the question, is not to go traipsing through known convective buildups, but more due to unforecast, or changing conditions creating a more serious situation than was forecast during preflight planning and identifying that situation correctly.  And I’m curious what other pilots use as their benchmark.

This is the way I took your response, but using icing as the subject, vice turbulence, to illustrate the way your response reads to me.   if this is not what you intended please let me know:  Think of my question as being more like “how can I tell if the icing is more serious than moderate as I’m punching through a layer in my FIKI TKS Bravo”, and your response being “don’t go flying if there is any chance of icing.”  I would say that your advice is conservative in nature (don’t go flying if their is a chance of turbulence), but not all that practical, or realistic.  Or did you just mean a chance of moderate turbulence (an airmet issued, maybe?). Still, that seems a bit conservative.

edit: I read your paper on your experience in the ovation on turbulence. How does putting the gear down and deploying the spoilers aerodynamically “help” with the turbulence?  Is the ride markedly different than just flying the aircraft below gear deployment speed (125ish knots? So just below maneuvering speed). I’ve never heard of this technique before, is this a common thing in light GA planes?  it seems inefficient, but if it helps the ride dampened out maybe worth it?

Although more inefficient, extending the gear and even the speed brakes give more stability, as the gear acts like a rudder to dampen the effects of the turbulence. Other than using them to assist in the "dive and drive" approach, never run an approach with the speed brakes extended for the whole approach.  In a downdraft near the runway you may not have enough power to climb out of it.

Yes, there are mountains around Klamath Falls, but I have yet to experience much turbulence there when flying in the morning hours.  Of course this assumes not fronts passing through.  In fact, when I go cross country I usually limit my flying to 6 hours between 6 am and noon.  For me there are exceptions if I'm ferrying an airplane without any passengers.   In that case I will expect some afternoon turbulence if not flying in a turbocharged airplane that can get up to at least 15K AGL.

In my 50 years of flying (I just got the Wright Brothers Master Pilot Award) I have called it a day and landed once because of turbulence in Wyoming where the ceilings were 11K and the ground is at 5K.   There were no other good options.  So again, planning is the key to a comfortable flight.  With our modern weather capabilities that will provide pretty accurate data out to at least 4 hours, you should know pretty much what to expect along your route of flight.  With negative lifted indexes and high K factors in the midwest in the summertime, just forget about flying in the afternoon, as there is almost a certainty of fireworks being generated.

The Mooney whose wings came off over the Tehachapi Mountains about 15 years ago did so after flying into a thunderstorm.  I knew the pilot, as we had just taken a high altitude training course in Sacramento the week before.  He had a wife and 7 month old baby.  The day he tried to make it down to LA was TERRIBLE!  I called off a training flight due to the extreme convective clouds around that day.  That accident should not have happened.  It was not a day to be flying light aircraft.

[jlunseth]

I, like probably everyone else, prefer avoidance to penetration.  One of the great things about the iPad and “rubber banding,” is the ability to see fronts graphically, and then quickly plot a course around the front instead of through.  You can do the same on the modern GPS’s, I just don’t happen to have one in my aircraft, I have the 430, so I use the iPad.  My experience is that there are not very many times when you are stuck with a route through convection.  Usually you can see it coming a long way off now, and it is better to spend the night on someone’s mattress on the floor somewhere, than trying to penetrate.  The few situations where it seems to still happen to me occasionally are, (1) flying an approach, and the approach goes right through a Tstorm, (2) flying in the mountains and finding out there is no good route except straight through the cloud ahead, because the MEAs and surrounding hard won’t let you go anywhere else, and (3) on occasion, making a descent and there is just too much stuff in the way to go around or avoid.  When I have to do it, I drop to NA always.  Among other things, the bumps are less severe.  Its still not comfortable.  I haven’t tried the gear down method, but I think I will next time to see if it helps - if there is a next time.  I like my airframe, I want to keep my airframe.

[Mark89114]

I have never worried about the wing coming apart....i have always worried about the horizontal stabilizer.....it just doesnt seem as solidly attached, dont know what the load is on it....and then you see what the hinge bracket looks like, nnot much....yes irrational fear but when i was flying jets had the same "worry", sometimes they mounted stab way high up in the air at the top or middle of a vertical stab, seemed to me like there would be more loading and arm length to bend something.  There is zero basis for my concern based on any facts.  Well off to the therapist now.  Fly safe.

[Jeff_S]

1 hour ago, jlunseth said:

I, like probably everyone else, prefer avoidance to penetration.  

Speak for yourself!  

Oh, you're talking about turbulence...my bad.