Spins prohibited

[Alan Fox]

Agreed. Guys, I keep coming back to this. Get an AOA indicator! After seeing it creep critically low in some heavyweight or steep turns (with what would appear to be a fair bit of airspeed), I have learned a ton about stall prevention in my aircraft. It has also saved me when climbing out at extensively varying weight conditions from 250-980lbs of payload. Watching the airspeed indicator alone won't save you from stalling cause you don't always know what speed at that weight, flap, or turn condition will cause you to exceed the critical angle of attack. The AOA doesn't care and tells you what your margin from stalling is at whatever condition you are in at the moment. In retrospect my flight instructors did a thoroughly inadequate job preparing me to realize the many other ways to induce a stall because we pretty much only focused on straight power on/off stalls in the same weight configuration!

All airplanes have an AOA .... Its called the stall horn....

[RocketAviator]

All airplanes have an AOA .... Its called the stall horn....

 

ALL, maybe not All, I have flown one plane that did not have a stall horn recently a Lancair 4P I was also read that a Citabria did not have one, so maybe there others that I don't know of too1

Fly Safe,

Rocket On!   

 

, 

[Earl]

Well I have stalled my 252 numerous times including power on, power off and have never noticed anything unusual in terms of tendency to spin.  But after reading this when I do my BFR next month I am going to insist we do the stalls at 5,000'.

[jlunseth]

 

I myself keep the speed at 90kts or higher, lower the flaps on down wind before the turn and maintain 90 kts until stablished on short final.  

José

That is exactly what I do. I remain at 90 kts. until established on short final. I put in takeoff flaps when abeam the runway on downwind. If I use full flaps, I generally do not deploy them until on final, and I generally do that only in low/calm wind conditions when I am planning a landing in still air at 75 kts. or under. If in strong, gusty winds or crosswinds I don't deploy full flaps.

In some unusual situations I will deploy full flaps for the braking effect in strong winds, but the circumstances are generally very unusual, and I generally don't leave them out for the touchdown.

[Dart106]

It appears, that I am a few years late to this discussion, but thought I should reply anyway. It is NOT the laminar flow wing that prohibits the spins. Many planes have laminar flow wings. (Comanche being one great example) The problem, lies with the "slickness" of the airfame. During the recovery, it is not difficult at all, to exceed the Mooney's VNE speed, and fold the wings up over your ears! I am surprised that none of you mentioned that.

[DXB]

18 minutes ago, Dart106 said:

It appears, that I am a few years late to this discussion, but thought I should reply anyway. It is NOT the laminar flow wing that prohibits the spins. Many planes have laminar flow wings. (Comanche being one great example) The problem, lies with the "slickness" of the airfame. During the recovery, it is not difficult at all, to exceed the Mooney's VNE speed, and fold the wings up over your ears! I am surprised that none of you mentioned that.

I have NEVER heard of any metal M20  "folding the wings up over your ears" during a spin or from crossing Vne.  Do you have any info to substantiate.  

[skydvrboy]

I think the fold your wings comment is a great exaggeration, but he is right on why spins are prohibited.  Bob Kramer gave a great presentation on Mooney aerodynamics at Mooney Summit last year in which he showed video of the spin testing.  According to Bob, they decided never to approve spins because recovery required 195 mph and Vne is 200.  That simply didn’t leave enough room for pilot error.

I seriously doubt the wing would fold, but something is going to get permanently bent.

[carusoam]

2 hours ago, Dart106 said:

It appears, that I am a few years late to this discussion, but thought I should reply anyway. It is NOT the laminar flow wing that prohibits the spins. Many planes have laminar flow wings. (Comanche being one great example) The problem, lies with the "slickness" of the airfame. During the recovery, it is not difficult at all, to exceed the Mooney's VNE speed, and fold the wings up over your ears! I am surprised that none of you mentioned that.

Welcome aboard, Dart.

What brings you to MooneySpace?

You are going to be one of our best Necro-posters...

Did you come from the Comanche Society? 

Hope you can stay around.

Best regards,

-a-

[gsxrpilot]

I can testify that the wings don't fold up at Vne. Speaking for a friend...

[tigers2007]

But isn’t the entire tail assembly held on by a single bolt? That’s what gives me the chills when in really rough air — are the tail feathers going to leave me?


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[takair]

8 minutes ago, tigers2007 said:

But isn’t the entire tail assembly held on by a single bolt? That’s what gives me the chills when in really rough air — are the tail feathers going to leave me?


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Really two pivot bolts and the jack screw for trim.  The tail is quite robust.

[David_H]

Just now, takair said:

Really two pivot bolts and the jack screw for trim.  The tail is quite robust.

... this is in addition to the hinge plate assembly.

A lot of aluminum would likely buckle before the two hinge pins sheared. That said, it's not a bad idea to check the lock nuts to ensure they haven't moved from time to time.

[gsxrpilot]

15 minutes ago, tigers2007 said:

But isn’t the entire tail assembly held on by a single bolt? That’s what gives me the chills when in really rough air — are the tail feathers going to leave me?

Didn't Bill Wheat test fly the Mooney to certification standards with a much too skinny hardware store bolt holding the tail on, just to prove it?

As long as it gets checked every year at annual, I'm confident there is nothing I'm gonna do that will break the airplane in the air.

[kellym]

16 minutes ago, gsxrpilot said:

Didn't Bill Wheat test fly the Mooney to certification standards with a much too skinny hardware store bolt holding the tail on, just to prove it?

As long as it gets checked every year at annual, I'm confident there is nothing I'm gonna do that will break the airplane in the air.

No, he tested the aircraft without the bushings that go with the bolts.  The bolts were the proper ones.

Two main reasons you don't want to spin a Mooney.....the rudder is too small and too slow to stop the rotation quickly, and the long wings also make the stopping of the roll slow.

But much of this discussion about stalls, loading and speeds is too generic. There is a big difference in Vne in a pre-68 model and later models, the short bodies have a different moment and the rudder up until around 68 is shorter. You can''t do 90 knots and lower the flaps at all...87 kts or 100 mph is max flap speed.  Main issue with stalls is that you must keep the controls coordinated with the ball in the center. Cross control is very risky in stall, very likely to initiate a spin.

[gsxrpilot]

21 minutes ago, kellym said:

No, he tested the aircraft without the bushings that go with the bolts.  The bolts were the proper ones.

Yeah, that's what it was. Thanks.

[tigers2007]

What’s the ideal IAS for a slip to lose altitude then? Isn’t that a grossly exaggerated cross control event?


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[Andy95W]

The greater the speed, the greater the drag produced by a slip, so the most altitude loss.  That basically means if you have flaps out, Vfe.  If no flaps, then you could certainly push that up to Va, and for a really steep descent, Vno/top of the green arc.  At that speed you'd probably scare Evel Knievel (and he's been dead since 2007).

[carusoam]

3 hours ago, tigers2007 said:

What’s the ideal IAS for a slip to lose altitude then? Isn’t that a grossly exaggerated cross control event?


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Waiting for a CFI for this...

But in the mean time...

0) Speed... the faster you are going, the more energy you need to lose...

Altitude.... the higher you are, the more energy you need to lose...

Energy lost is a squared function of the speed you are traveling at...

So... turning sideways, increases the CSA cross sectional area... part of the friction equation... speed is the other part...

Ideally, you plan in advance and don’t ever need this to lose lots of energy... it is used to adjust smaller amounts of energy when things are not meeting your plan...

Emergency descents with no speed brakes... you need to get down now. Check the procedure for emergency descents... it probably includes... throttle out, prop in, gear down, increase speed to gear down speed, slip like crazy at gear down speed... aviate, communicate, checklists.... you are going to be on the ground in minutes... be prepared...

1) Transition in and out of the slip, smoothly... it isn’t a stomp and jerk set of motions...

2) Most important... when using this maneuver to lose energy... (speed and altitude) keeping the nose actively pointed downwards is your friend...

3) If there is no stall, there is no spin...

4) lowering the nose, unweights the wings, minimizing the 1g stall speed requirement...  yes it can still stall, but at a lower speed...

5) If the nose is pointed down, recovery from a pre-stall situation is already under way... yes it can still stall, but you are already doing the right thing...

6) Remember... if your foot slips off the rudder pedals while fully cross controlled... that is a set-up for changing the airflow over your airfoils...

7) Mooneys are incredibly strong, and don’t usually bight... until you slip up...

8) leave some room for slip-ups, and mistakes... at TPA, there isn’t much room for stall recovery...

9) Do all your testing at an imaginary TPA, many thousands of feet above the normal TPA.

 

To be clear... this is a PP thought only, not coming from a CFI... ask more questions...

Check with a Mooney CFII for better details for your specific bird...

Best regards,

-a-

[steingar]

I've read accounts of folks recovering from spins in Mooneys that were to say the least, harrowing.  Won't keep me from practicing stalls, might keep me from practicing them cross controlled.  Keep your speed up and step on the ball.

[M20F]

Vne won’t be exceeded in a spin.  A spin is an aerobatic maneuver where you rotate around at slightly over stall speed.  
 

A spiral is what happens when you release back pressure in a spin.  It comes with ever increasing air speed.  

Spinning a Mooney is survivable as evidenced by several here (it is again a maneuver).  You take a very slick airframe though and the ever increasing speed of a spiral you can certainly have some problems trying to break out or bending things due to the G’s of breaking out well beyond Vne.  

My experience is most people can’t hold a spin which is the problem (failure to adequately perform the maneuver), not the maneuver itself.  Certainly an inadvertent spin is almost always going to lead to a spiral.

[kellym]

On 1/11/2020 at 9:53 PM, DXB said:

I have NEVER heard of any metal M20  "folding the wings up over your ears" during a spin or from crossing Vne.  Do you have any info to substantiate.  

Well, there is at least one documented case of in-flight breakup, exiting the bottom of a Cat 5 T-storm with icing, and an incident of a different Mooney exiting another T storm that required estimated 12 G pull up to recover that popped some rivets and wrinkled some skins. Factory made the G estimate based on the damage.

The real risk of exceeding Vne is flutter and potential for a control surface to depart the airframe due to flutter.  The problem with spins is not so much airframe damage as it is actually regaining controlled flight before the ground rises up to smite thee.

[kellym]

23 hours ago, M20F said:

Vne won’t be exceeded in a spin.  A spin is an aerobatic maneuver where you rotate around at slightly over stall speed.  
 

A spiral is what happens when you release back pressure in a spin.  It comes with ever increasing air speed.  

Spinning a Mooney is survivable as evidenced by several here (it is again a maneuver).  You take a very slick airframe though and the ever increasing speed of a spiral you can certainly have some problems trying to break out or bending things due to the G’s of breaking out well beyond Vne.  

My experience is most people can’t hold a spin which is the problem (failure to adequately perform the maneuver), not the maneuver itself.  Certainly an inadvertent spin is almost always going to lead to a spiral.

Uhhem,

Either I misunderstand what you are trying to say or you don't really understand the situation.  The issue with Vne is not while IN a spin, it is during the recovery, after you have stopped the rotation, because you will be at a very nose low attitude, gaining speed rapidly.  Holding a Mooney in a spin isn't the problem, it is getting out of the spin, and it is necessary to both stop the turn and break the stall, which requires forward pitch long enough to break the stall, and then restoring a normal attitude at a rate that doesn't generate a secondary stall and doesn't exceed Vne.  The Mooney rudder is not particularly effective at stopping the turn.  A Cessna takes effort to initiate a spin and maintain it. The Mooney is very different.

A spiral is normally encountered when in IMC and when not realizing you are turning.  It has very little in common with a spin or spin recovery, although I suppose if the turn isn't fully stopped in a spin recovery it could happen. I'd like to hear thoughts on the subject from experienced CFII.

[DXB]

1 hour ago, kellym said:

Well, there is at least one documented case of in-flight breakup, exiting the bottom of a Cat 5 T-storm with icing, and an incident of a different Mooney exiting another T storm that required estimated 12 G pull up to recover that popped some rivets and wrinkled some skins. Factory made the G estimate based on the damage.

The real risk of exceeding Vne is flutter and potential for a control surface to depart the airframe due to flutter.  The problem with spins is not so much airframe damage as it is actually regaining controlled flight before the ground rises up to smite thee.

Are you talking about this case in reference to the "in-flight breakup?"     

https://www.ntsb.gov/_layouts/ntsb.aviation/brief2.aspx?ev_id=20001211X10119&ntsbno=LAX98FA154&akey=1

The horizontal stab failed on that one, not the wings. Agree that on Mooneys Vne has everything to do with horizontal stab flutter and little to do with loading the wings, which are ridiculously overengineered.

[RobertGary1]

Bill Wheat told me they spun Mooney airframes for the FAA on many occasions. He said the spin behavior and recovery were very conventional but the altitude loss after a full turn was quite a lot. There wasn't much advantage in certifying the aircraft for spins so the spin prohibition is required by the FAA.

There is a video out here on youtube of a guy accidently entering a spin in a Mooney. He recovers pretty quickly so altitude lose was minimal.

Resident CFI Don Kaye has spun a Mooney and reported the same; altitude loss was a lot.

-Robert

[David Lloyd]

That inflight breakup was because the pilot already lost control of the airplane.  Exceeding VNE or V...uh senior moment (maneuvering speed) in rough air is loosing control of the airplane.  You've done it, I've done it, we got away with it.  That time.  This pilot did not.  That time.

Many years ago when Aviation Consumer launched it's attack on the V-tail Bo, one of the magazine articles said that the V-tail and straight tail (F33A) hit the ground at about the same rate.  Only difference was the V-tail hit the ground in many pieces.  After a million words were written, it was found on the V-tail that the leading edge of the stabilizer would deform and fold in excess of 300 mph.  Bad things would happen then. (bad things were already happening if you were indicating 300 in a Bo) Usually one would fail up, the other down, pull the rest of tail off, pitch nose down, fold the wings down breaking off at least one. There was some reason the F33A would not fold a stabilizer before arriving at the ground. 35 Years has clouded that memory.  Maybe they just flew lower.  Somewhere in the midst of all the AC stories, one of their frequent writers lost control of his V and provided some ugly pictures.  Also in the period, someone lost control of an A36 turbocharged Bo, flying near or through a thunderstorm at FL250. Broke the tail, pitched down, broke the wings. AC had a sketch showing the hapless pilot strapped in his seat exiting the plane through the roof. I think this was the first straight tail Bo ever to break up in flight.  Try hard enough, you can make it happen.  I think Mooney has been in the same position, in flight breakups being extremely rare.

Sorry, back to the OP.  Spin testing was done. If the airplane would not come out of a spin under certain circumstances dictated by the FAA, the airplane would not be certified.  There are other things in consideration for not allowing spins, some of which are at the say of the manufacturer.  One would be as others pointed out, a nose low attitude during recovery.  As others have said, aslick airplane builds speed quickly when the nose is pointed straight down. If you unexpectedly enter a spin, let it develop for a turn or so, I think it would be difficult to recover without exceeding VNE.  Think about closing your eyes, having someone pitch your airplane down 60 degrees and 90 knots.  Open your eyes and get back to level flight.  Did you exceed VNE? 3.8 G's? Was the air smooth? Well, could you do it on the next try?  Sometimes we don't get two chances.

Several years back I built an RV7 with a Dynon Skyview panel.  The autopilot had a LEVEL button that when pushed would roll the plane wings level and pitch level.  Modern version of Mooney's PC.  The pitch was limited to 2 G's I think, and would (try to) keep the airspeed below redline.  Worked great at normal speeds, pitches and banks.  It would not recover from a spin.  Oh boy, that was fun!  After two turns it slings the spit right out of your mouth.  At normal cruise speed if the roll was more than 90 degrees or so, it would exceed VNE with cruise power.  Pitch up or down 45 degrees, the throttle would have to come back to idle immediately to avoid VNE while recovering from a 90 degree bank.  If you were clumsy enough to get in an attitude like that, could you do better than the machine.  Probably not.  The RV was rated for 6 G's, doing aero stuff I never exceed 3.5 G's, usually not more than 3.  3.5 Was my limit for fun, 4 was uncomfortable, 5 hurt.  Other people I invited to throw the RV around a little rarely exceeded 1.5. I don't recall anyone ever pulling more than 2.  So, if you were going to recover from an unusual attitude in your Mooney, would you pull more than 2 G's during recovery?  Would you panic and pull much more than 3.8?

So, if you really want to spin something, don't pick on something slick like a Mooney or Bonanza.