How strong is the M20 wing?

[Shadrach]

A place of learning........

How do the last few posts promote this?

DS,

Please don't get your feathers ruffled. I have seen you take a pretty aggressive stance when taking folks to task regarding statements you disagree with. You're relatively opinionated on most subjects (you have a detonation curve for an Avatar for Pete's sake)  Forgive me if when I read the post quoted below I did not see you as a humble seeker of knowledge and  more of a pot stirrer.

I like this discussion. Lots of explanation and patience on both sides.....input eyes rolling emoticon here.

Wondering what happens when folks realize Vne is TAS.

Proud of Pete for sticking to his guns.

We're all wrong from time to time, how we handle being wrong says far more about us than how often we are right...

 

[MyNameIsNobody]

Cause and effect.  Set 'em up, knock 'em down.  Call me out as unsafe back it up with mumbo jumbo...Cause.  Expect response, generally sarcastic, requesting clarification.  Effect.

Some "throw stuff out" as absolute fact.  Others challenge.  Some, like me, do it in a different way.  To some that is challenged as being "harsh", "critical", "sophomoric".

I enjoy this thread except for those that wish to applaud those with one rigid mindset without "proof"...and call those that challenge heretics.

Burn me at the stake...

[MyNameIsNobody]

Quick, don't look now but someone on another thread is advocating landing with flaps as desired...NOT FULL FLAPS!  Get the torch's!  Storm the castle!  Stop the heretic!

[MyNameIsNobody]

I enjoy the "I do it because the POH says so" crowd.  Never-mind that experience and trial over decades determines that change is not only warranted, but done.  You all need to ask "why this way"...at least once and a while.  Get out of the missionary position once a week.  You might not just find that something is not only safe, but practical and dare I say it...fun.

[bonal]

Not even sure why this is in debate we fly aircraft with known Vne and that is the limit we should respect if your about to exceed you need to slow it down. I can see where flying in the yellow could be more subjective as to the degree of turbulence you think is safe. There must be a level of trust in our airplanes design and condition or no one in their right mind would take to the sky

[aviatoreb]

Not even sure why this is in debate we fly aircraft with known Vne and that is the limit we should respect if your about to exceed you need to slow it down. I can see where flying in the yellow could be more subjective as to the degree of turbulence you think is safe. There must be a level of trust in our airplanes design and condition or no one in their right mind would take to the sky

I agree with "if you are about to exceed vne, you should slow down." 

In some sense, that is all we need to know.  Anymore is good to know - and as an educator, I am a big fan of its good to know as much as possible.

As an aside, I have the p2 audio system that I got installed in my airplane as soon as I purchased it about 5+ years ago.  I got it because it gives an audible english warning if your gear is up when you are trying to land. "Check Gear!  Check gear!"  But also it has a built in feature that warns of Vne, "Overspeed!  Overspeed!"  When you install it you get to have that alarm go off at a preset speed and the little pin diagram has by model the suggestion for the M20K to be at Vne of 196 - I chose to set it slightly differently so it yells "Overspeed" at me if I go faster than 192IAS (that was the next lowest pin setting as I remember).  The reason I did this is I didnt want to hear I am going to fast after I go to fast but before I go to fast with a bit of time to do something about it.

[Hank]

Quick, don't look now but someone on another thread is advocating landing with flaps as desired...NOT FULL FLAPS!  Get the torch's!  Storm the castle!  Stop the heretic!

This heretic does so BECAUSE THAT'S WHAT MY OWNERS MANUAL SAYS TO DO.

If yours says something different, maybe it's because you don't also fly a C model.

Or should I fly using a different POH/Owners Manual than came with the plane? I don't think so!

Edited September 7, 2015 by Hank

[MyNameIsNobody]

This heretic does so BECAUSE THAT'S WHAT MY OWNERS MANUAL SAYS TO DO.

If yours says something different, maybe it's because you don't also fly a C model.

Or should I fly using a different POH/Owners Manual than came with the plane? I don't think so!

Hank, That was my tongue in cheek point.  You have discression as PIC.  There are a lot of different AND acceptable ways to operate your vintage Mooney safely.  Experience  DOES count and gives options.  Engineers and aircraft designers continue to learn and implemented changes.  Superior ways to operate and maintain your aircraft.  I celebrate your "right" to operate your plane as you wish.  I live in realsville where making decisions on how you fly your plane taking into account your POH as well as lessons learned makes you a better pilot/owner and decision-maker.  I am the last person to call you out as unsafe.

[DS1980]

I say these things to further the discussion. I did the same thing to mooniac15u in the exact same discussion. I wanted Pete to continue to explain why he thought Vne was a TAS, but instead he was shot down.

I wanted it to progress to the point where the discussion turned to WHY is Vne, not WHAT. It never made it there.

I will reiterate that even suggesting someone do something dangerous in their airplane to make a point is still pushing the limits.

Of course Vne is an IAS. It's also worthless to think of it in this manner.

I have been asked many times about what my avatar is. I have helped more people sort out LOP and engine operation than you know.

Shadrach, I enjoy the hell out of you. I completely respect you as a pilot and a person. We would kick ass in a bar fight.

Edited September 9, 2015 by DS1980

[ShuRugal]

Just bumped into this thread on google.  Sorry for the gravedig, but there are some interesting posts in here...

 

Quote

I have heard that Mooney Hired Al Pietsch from ND to do dive tests on the Mooney. I heard that he took it to over 300KTS and pulled in excess of 9Gs without any damage.

 

You could call his son Warren Pietsch at Minot Aero Center for more details.

 

Does this mean that the 189 MIAS Vne in my '64 C has an implicit "under non-emergency circumstances"?  What about Va of 132?

 

Are those numbers published to keep GA pilots within a safe and comfortable limit, more than they are to keep the plane from disintegrating? 

 

On 9/2/2015 at 1:51 PM, cnoe said:

In the Bo forum the thinking was that their tail-feathers departed due to air-speed induced flutter long before any ultimate g-load was surpassed. If the 300 kt/mph test flight is true then it's nice to know that "flutter" is not a primary concern. And it also sounds like g-loading of the wing isn't a huge concern either.

 

I've seen the pic of the factory guys standing on the wings, and I've also heard the tale of the test-jig breaking, but I didn't know the related numbers. It would be interesting to hear the "numbers" from an authoritative source.

 

If the wing and airframe are as strong as legend has it then I'd likely pass out well before breaking the wings off in a simple "pull" from a steep dive. Does anybody disagree?

 

Skimming through the thread, I couldn't find if anyone had the numbers from an authoritative source, as cnoe was asking about.  It would be interesting to know the "test limits" of the aircraft, in addition to the book limits.  Not that I intend to exceed the book limits, but if test-limits indicate that the book-limits give me a safety factor of 2 or 3, rather than 1.3, I will be less inclined to worry about what the gauges are doing when shit starts looking pear-shaped.  

 

In a true emergency, the ability to focus on flying the plane without worrying about whether it is about to disintegrate could be life-saving.

[mike_elliott]

1 hour ago, ShuRugal said:

Does this mean that the 189 MIAS Vne in my '64 C has an implicit "under non-emergency circumstances"?  What about Va of 132

You have to know how VA is derived. VA is the square root of 3.8 (the positive G certification requirement) times the stall speed at a given weight. Thats why VA is higher when you are heavier. Does it mean it wont break up at a higher speed? No, it just means it is only certified to 3.8G+

[jaylw314]

Also, Va only takes into account maximum constant pitch up elevator movement.  If you pitch down or apply aileron/rudder, you may or may not have less margin of safety before the structural limit.  Also, you can exceed the structural limit below Va with dynamic pitch up controls, e.g. applying up elevator rapidly or rapidly alternating from pitch down to pitch up.  If I remember correctly, that's how AA 587 had a vertical stab failure on takeoff

[takair]

Regarding Vne, there are more things that go into this than pure structural loads.  The primary one is flutter.  This can be insidious and can be provoked in various ways.  It depends on the balance of the surfaces, tightness of control rods and hinges, repairs to the airframe, etc.  There is certainly margin designed into the airframe, but that assumes everything is within the expected limits.  With our aging airframes, I’m sure some margin is eroded.  Now, I’ve never heard of this occurring on a Mooney, but I also wouldn’t want to be the first to discover the terrible combination.  One of the required ingredients is almost surely a speed over Vne, so that one is typically in our control....at least when in control.

[Andy95W]

[Geoff]

On 9/2/2015 at 6:42 PM, mooniac15u said:

At any rate, there are probably two key takeaways from this:

 

1) Mooneys can and do break up in flight.

2) Mooney expects the onset of flutter to be around 240 knots in the mid body airframe.

What about the long bodies?  Doesn’t the Acclaim do 242 knots regularly?

[takair]

9 minutes ago, Geoff said:

What about the long bodies?  Doesn’t the Acclaim do 242 knots regularly?

Vne is still only 194kias.  242 is true airspeed.

[mooniac15u]

51 minutes ago, takair said:

Vne is still only 194kias.  242 is true airspeed.

The 240 kt expected flutter speed is also a true airspeed.

[mooniac15u]

1 hour ago, Geoff said:

What about the long bodies?  Doesn’t the Acclaim do 242 knots regularly?

The 240 knots was for an M20K. Presumably there are structural differences for the Acclaim. 

[Geoff]

Does anyone know what they are or can confirm that it is true?

[carusoam]

I know exceeding maneuvering speed into turbulent air is bad....  picture flying into a 2’000 fpm updraft...

the idea behind this number is...

Below this number, the wing stalls, prior to the wing being fully loaded...

Above this speed, The Wing exceeds its design strength, before stalling...

3.8 gs is a lot of force...

The average pilot will feel like he is weighing 665 pounds. 3.8 X 175....

 

Vne has the flutter and other issues outlined above.

 

This is a great question.  Much better to know the answer, than to exceed the limitations unknowingly...

 

This is one of the legs of the airplane stool... avoid thunderstorms... this is where you can run into some extreme vertical winds.

They are something like 2k fpm up, and 6k fpm down.

Staying out of clouds makes it kind of easy to follow, accept somebody invented a term called CAT, for clear air turbulence....

 

So if you live in a turbulent area, the long body has some nicer yellow arcs and redlines than the older planes.....

 

PP thoughts only, not a CFI....

Best regards,

-a-

[Yetti]

In smooth air while decending sometimes I go a little bit into the yellow arc.   The rest of the time I am fine with not putting a 50 year old aluminum can near it's engineered limits. "Always be airline smooth"

[Mooneymite]

Just for a little variety, think about Vne as displayed on (many) jets.  Vne is not a red line across the airspeed indicator, it is displayed as a red/white needle commonly called the "barber pole" which moves accoeding to how the engineers program it..

Just like our red lines, from the pilot's perspective it's simple...don't exceed it.  It makes the klacker go off and it makes the cockpit noisy.  However, what's germaine to this discussion is what drives the barber pole.

Sometimes it is an indicated airspeed (maybe 350 Kts), sometimes it's a Mach (like .85), sometimes it is programmed to protect the windshields from low altitude bird strikes (like 250 kts below 8000').  There are many other speed limitations which we might not think about....a certain jet may have a max flap speed of 250 knots, but not above a certain altitude because of structural Mach considerations when the accelerated air over the flaps approaches Mach 1.  I suspect the Mooney engineers considered many factors and under the right conditions, our Vne is very conservative, but they picked one number to keep us safe in almost every corner of the envelope.

Discussions of Vne usually center on max structural speed, but in reality Vne is highly dependent on how high, in what configuration and how fast and how the data were presented to the FAA during certification.

Happily, all we have to do is observe Vne.  

[Browncbr1]

22 hours ago, carusoam said:

I know exceeding maneuvering speed into turbulent air is bad....  picture flying into a 2’000 fpm updraft...

the idea behind this number is...

Below this number, the wing stalls, prior to the wing being fully loaded...

Above this speed, The Wing exceeds its design strength, before stalling...

3.8 gs is a lot of force...

The average pilot will feel like he is weighing 665 pounds. 3.8 X 175....

 

Vne has the flutter and other issues outlined above.

 

This is a great question.  Much better to know the answer, than to exceed the limitations unknowingly...

 

This is one of the legs of the airplane stool... avoid thunderstorms... this is where you can run into some extreme vertical winds.

They are something like 2k fpm up, and 6k fpm down.

Staying out of clouds makes it kind of easy to follow, accept somebody invented a term called CAT, for clear air turbulence....

 

So if you live in a turbulent area, the long body has some nicer yellow arcs and redlines than the older planes.....

 

PP thoughts only, not a CFI....

Best regards,

-a-

Thanks for clarifying exactly what performance factors dictate Va.    based on this, it seems reasonable to think that structural limits have been exceeded or close to limit if turbulence makes the stall horn sound above Va for the applicable loading.  

I flew aerobatics as part of my PPL training.  3.8gs is a lot if sustained.   I flew up to 6Gs.   It’s easier to discern sustained Gs compared to sudden turbulence induced loads.  I have a D2 with G meter memory.  I’ll have to remember to look at it next time I’m in turbulence to see what kind of instantaneous loads are put on the airframe.  

[N201MKTurbo]

All this talk of maintaining an airspeed in severe turbulence is academic. when the turbulence gets that bad you are lucky to keep the airspeed within 180 degrees on the gauge. It is best to set the power according to the VSI and keep the plane as level as possible. By setting the power by the VSI I mean if it is pegged on the bottom use full power, if it is pegged on the top bring it back to idle. And pray for your airframe!

[Navy79]

Lively discussion back in the day.  Minnesota crash brings it back to the forefront.