Can you slip a Mooney on final?

[cferr59]

I'm a new Mooney pilot, but I've slipped my C model and never considered it would be an issue.  The only aircraft I've flow that I haven't slipped is a T-Tail Lance and that is because it glides like a brick so slips are not necessary.

[jlunseth]

The title of this thread (which is a very old one) is a little misleading, because the short, mid, and long bodies are three different issues.  You can’t just lump them together and say that “Mooneys” should or should not be slipped on final.  We have had several threads about the elevator stall issue in the “longer” bodies. The issue is more likely in the long bodies than the mid or short bodies.  

I can tell you from Upset Recovery experience in the Extra 300 that you do not want to enter a cross-controlled stall at low altitude.  The aircraft inverts with very little or no warning. Recovery is possible, but not in 400-500 feet. Someone posted earlier in this thread about the tendency of Mooneys to invert suddenly in a cross-controlled stall.  I can tell you that you don’t want to go there.

I use forward slips very rarely, and when I do I keep the aircraft at or above best glide, which is 81-85 (varies with gross wgt.) in my 231.  There are other ways of losing speed quickly on final. I don’t worry about sideslips on landing because the whole idea is to get the aircraft to stop flying, but I don’t like to do them until right above the runway.

[mooneyflyer]

On 12/14/2009 at 1:36 PM, Piloto said:

Of course you can slip your Mooney or any FAA approved airplane. It is a required capability for crosswind landing particularly on high wing planes. Sliping into wind reduces the possibility of weather vane into the cross wind at touch down or flip over. To avoid an inadvert stall your approach speed should be slightly higher during the slip.

 

José

 

 

  

 

Long body Mooneys have a clause prohibiting slips with flaps extended.

[Ibra]

J specific only !

On stalls & sideslip: as long as you go forward on sideslip (not turning) there is no issue with stall in that configuration, actually the on-the-top stall with sideslip forward motion is the most benign stall one can have: if you recover quickly the aircraft will tend just sort itslef when you unload any of the 3 surfaces, elevator or ailerons or rudder 

Only issue is stall at sligthly higher speed as low wing will hit max AoA (about 20deg turn stall speed adjustment) but in the other hand releasing ruder or dropping wing brings you back to safer stall speeds, you don't have that luxury in any other stall forms including coordinated symetric stalls (bit like recovering from early flap cleaning by putting them down between Vs0/Vs1 or killing the live engine on twins bellow Vmc)

Skid/slipping/symetric turn stalls are different beasts, technically forward sideslip stops when you start turning, usually about 20deg ailerons bank when full ruder is not be able to stop the turn, when the aircraft is turning it is different, so better statement: I would not make any turn at low speed & height, coordinated turn or uncoordinated slip turn or uncoordinated skid turn 

Happy to stall on forward sideslip in every cross wind day landing (well it has to go slow & uncoordinated at some point?) as long as I am tracking the runway line above the threshold, sometimes at 50ft agl, so far nothing fancy happens like loss of control, drop wing or spin...just keep some speed and 0.9G and don't abuse flaps, power and sideslip all combined while pulling 2G on final 

Edited May 13, 2020 by Ibra

[M20F-1968]

For those of us with speed brakes, is there any real need to slip the Mooney when speed brakes can be used to slow up and drop altitude?   Landing can also be done with speed brakes with more power.  The airplane then feels heavier and still stable.  I have done this with full flaps as well.  This seems to be a better option than slipping as feels like a better option.  I think it can safely be said that the only time cross controlling is essential is in a crosswind landing to align with the runway.  Even then, speed brakes and slightly increased power setting can be used.  Trying to keep things simple and unexciting.  Am I missing anything?

My plane also climbs with full flaps, gear and speed brakes with just myself onboard.

John Breda

[L. Trotter]

Late to this party.

Here is an article by Bob Kromer in regards to Slipping a Mooney. Also, if you have relatively full fuel tanks, you will see precious petro exit the low wing tank through the vent.

SLIPPING A MOONEY.docx

Edited May 13, 2020 by L. Trotter

[tmo]

10 hours ago, Targhee said:

stomped on the left pedal ... I then switched tanks and after a couple of seconds it smoothed out.  

During the pre-landing checks I noted I had about 15 gals total, 8 on the right and 7 on the left (the tank I was on).

So the safer way to slip is to do it with the tank opposite rudder direction?

[carusoam]

11 hours ago, Targhee said:

So, just though I’d share something that happened today in my 1983 M20J.  I was really high on an approach to landing and decided to side slip to reduce altitude quickly.  I stomped on the left pedal for a good 30 seconds to get down to the glide slope and then resumed a normal approach.  As soon as I pulled my foot off the rudder, the engine started running really rough and felt like it was about to quit on me (man that grabs your attention quickly!).  I was on glide slope at about 300 AGL, so even if it quit, I had the runway made.  I gave it a little more throttle, no change.  I then switched tanks and after a couple of seconds it smoothed out.  

During the pre-landing checks I noted I had about 15 gals total, 8 on the right and 7 on the left (the tank I was on).   After landing I did a run-up check.  No issues.  Several more trips in the pattern.  No issues.  I even went up to altitude and attempted to recreate the same landing approach with extended side slip.  No issues.

Driving home I remembered that small quote from the POH...  “Prolonged slideslips, steep descents, or takeoff maneuvers may cause loss of power if the selected fuel tank contains less than 48 lbs. (21.7 kg) (8 gallons - 30.3 liters - 6.6 Imp. Gal.) of fuel“...   Bingo!  

Moral of the story...  re-read your POH and don’t do extended slips in your Mooney if your on a tank with less than 8 gallons unless you want to soil your shorts.

Good thinking Targhee....

 

Great thread revival as well...

 

It is incredibly important for all pilots/all planes....

Know what corner of the fuel tank the fuel pick up is....

This will give you a hint to what will starve fuel at the end of your flight...

The Mooney design is as good as it gets...

The Mooney pilot needs to know the limitations of the plane... the more he knows the better off he will be...

This is one good topic of several for Transition Training...

 

Probably the worst case situation arises after a long flight...

• One tank may be completely empty... (intentional)
• the other tank is at minimum... (Still legal)
• you are on short final...
• a deer creeps across the runway...
• You are now in Go-around mode...
• Or... you don’t know how to ensure your fuel flow and land on top of a deer... 

 

Fuel pick-ups are intentionally placed...

• Near the low point of the tank. (While on the ground)
• Near the trailing edge of the wing.
• Near the root of the wing.

 

This allows you to have fuel during a go around in the final moments of your flight...

As PIC... you need to remember to keep that wing elevated... (no explanation required)

 

As for the statement (stomped on the rudder pedal....)

There is a reference from 2010 above... (still valid today)

’stomping for 30 seconds’ isn’t really stomping... is it?

Where a new Mooney pilot can run into trouble...

• Full control inputs...
• Sharp control inputs...
• In either direction.... full in or full out....
• Using full rudder, while going slowly, has some dangers associated with it...

While you were concerned about the engine continuing to run... were you concerned about the smooth transition in and out of the slip?

I’m sure you were... it just didn’t come out that way with the word ‘stomp...’
 

Cross control has some strategy to go with it... be familiar with the stall issues and how to avoid them...

Running out of fuel while cross controlling is an indication that there is even more to know...

PP thoughts only, not a CFI...

Best regards,

-a-

 

[aviatoreb]

I don't know.  But I have to be very careful on a winters day when the tarmac is snowy that when I step up on the wing, there might be still snow on my show, and I need to be sure to deliberately keep my hand on the baggage door handle since

- I HAVE slipped on my Mooney.

[carusoam]

Ceramic coatings will be more interesting for that...

Stay on the black coarse surface next to the ‘no step’ sign... 

-a- 

[bradp]

I’d think that you want the fuel in the same tank that your foot is pushing on the rudder in a forward slip.  
 

I bank left, push right rudder- the fuel sloshes downhill ie should be in the right tank.  I’d risk unporting the fuel if it was <8 gallons in my left tank.  

 

From primary training I had drilled into me that If you are slipping your wings should be unloaded to avoid a cross controlled high AoA situation. 

[Ibra]

48 minutes ago, carusoam said:

Or... you don’t know how to ensure your fuel flow and land on top of a deer... 

A very difficult task indeed, are these runway deers now ADSb equipped? 

[jlunseth]

4 hours ago, M20F-1968 said:

For those of us with speed brakes, is there any real need to slip the Mooney when speed brakes can be used to slow up and drop altitude?   Landing can also be done with speed brakes with more power.  The airplane then feels heavier and still stable.  I have done this with full flaps as well.  This seems to be a better option than slipping as feels like a better option.  I think it can safely be said that the only time cross controlling is essential is in a crosswind landing to align with the runway.  Even then, speed brakes and slightly increased power setting can be used.  Trying to keep things simple and unexciting.  Am I missing anything?

My plane also climbs with full flaps, gear and speed brakes with just myself onboard.

John Breda

In special, rare conditions I have used a technique I call “helicoptering.” Best glide gives you the most distance in a glide. So if you want less distance, throw out the speed brakes, idle the engine, put in full flaps for the drag, and slow to under best glide.  My best glide is 81-85, I drop to 70-75. Might need a little power right at the runway, like in a soft field landing, to arrest the descent rate.

[Targhee]

2 hours ago, carusoam said:

Good thinking Targhee....

 

Great thread revival as well...

 

It is incredibly important for all pilots/all planes....

Know what corner of the fuel tank the fuel pick up is....

This will give you a hint to what will starve fuel at the end of your flight...

The Mooney design is as good as it gets...

The Mooney pilot needs to know the limitations of the plane... the more he knows the better off he will be...

This is one good topic of several for Transition Training...

 

Probably the worst case situation arises after a long flight...

• One tank may be completely empty... (intentional)
• the other tank is at minimum... (Still legal)
• you are on short final...
• a deer creeps across the runway...
• You are now in Go-around mode...
• Or... you don’t know how to ensure your fuel flow and land on top of a deer... 

 

Fuel pick-ups are intentionally placed...

• Near the low point of the tank. (While on the ground)
• Near the trailing edge of the wing.
• Near the root of the wing.

 

This allows you to have fuel during a go around in the final moments of your flight...

As PIC... you need to remember to keep that wing elevated... (no explanation required)

 

As for the statement (stomped on the rudder pedal....)

There is a reference from 2010 above... (still valid today)

’stomping for 30 seconds’ isn’t really stomping... is it?

Where a new Mooney pilot can run into trouble...

• Full control inputs...
• Sharp control inputs...
• In either direction.... full in or full out....
• Using full rudder, while going slowly, has some dangers associated with it...

While you were concerned about the engine continuing to run... were you concerned about the smooth transition in and out of the slip?

I’m sure you were... it just didn’t come out that way with the word ‘stomp...’
 

Cross control has some strategy to go with it... be familiar with the stall issues and how to avoid them...

Running out of fuel while cross controlling is an indication that there is even more to know...

PP thoughts only, not a CFI...

Best regards,

-a-

 

Maybe "stomp" was a bad choice of words.  I should have said "I applied full and sustained left rudder".  The fuel flow issue didn't actually happen until I stopped the slip and was re-established on a standard approach.   Here is some interesting data from the EI engine monitor.  The fuel pressure dropped from 20 to 14 at the moment the engine felt like it was quitting.  As you can see, the pressure drop lasted about 30 seconds.

 

[carusoam]

Now that’s precision in discussion!  
including JPI graphs!

Another challenge for fuel flow occurs when the nose of the plane is pushed down... towards the runway.

Fuel in a large rectangular tank has  tendency to move around quite a bit...

Best regards,

-a-

[Ibra]

Nice to share that JPI data, you have 100seconds for FF to go zero after pressure drops? Guess it depends where two are measured? but these feel like 5seconds in real life, maybe related to heart beats, do you have that showing in JPI monitor 

I think it is hard to predict where the fuel goes inside an empty rectangular fuel tank when you go in/out of the sideslip, best is just have flexible fuel pipe sitting inside the tank and connected to an “acro fuel selector” but even that setup needs some fuel to work...

Edited May 13, 2020 by Ibra

[Hank]

1 hour ago, Ibra said:

I think it is hard to predict where the fuel goes inside an empty rectangular fuel tank when you go in/out of the sideslip, best is just have flexible fuel pipe sitting inside the tank and connected to an “acro fuel selector” but even that setup needs some fuel to work...

Your flexible fuel pickup line inside the tank.just needs a weight on the end of it. That's what RC airplanes use. But the tanks don't have sealer inside that will scrape off, and new tanks are pretty cheap . . . .

[Targhee]

On 5/13/2020 at 5:08 PM, Ibra said:

Nice to share that JPI data, you have 100seconds for FF to go zero after pressure drops? Guess it depends where two are measured? but these feel like 5seconds in real life, maybe related to heart beats, do you have that showing in JPI monitor 

I think it is hard to predict where the fuel goes inside an empty rectangular fuel tank when you go in/out of the sideslip, best is just have flexible fuel pipe sitting inside the tank and connected to an “acro fuel selector” but even that setup needs some fuel to work...

The whole "event" lasted 20-25 seconds.  I was on short final at the time, so the FF going low a minute later is the actual landing.

[jetdriven]

A couple of things, if you’re less than half tanks, always slip with the tank you’re feeding from on the high wing. Prevents fuel importing.  Look at the fuel selector. Raise that wing. 
Also, all of this worried about the stall. If you slip it’s because you’re high, so slipping at a lower airspeed is counterproductive. If you add 15-20kt to that, your plane will fall like a rock. Which is the objective here.  Then you can recover from the slip sooner, and have a Stabilized approach to the runway. So try this, mash  on the rudder, lift the wing, add 15 knots of airspeed.  

[ShuRugal]

On 5/13/2020 at 6:13 PM, Hank said:

Your flexible fuel pickup line inside the tank.just needs a weight on the end of it. That's what RC airplanes use. But the tanks don't have sealer inside that will scrape off, and new tanks are pretty cheap . . . .

Hmm, sounds like we need someone to get FAA PMA for a silicone-coated clunk.

[carusoam]

Unporting...  fuel running away from where it needs to be.

A word that Siri refuses to spell in an artificially intelligent way...

Sometimes it becomes importing, or unsporting...

-a-

[Ibra]

2 minutes ago, carusoam said:

Unporting...  fuel running away from where it needs to be.

“Unporting”: Not standard ICAO RT phraseology and goes beyond ELP6, but will keep it in mind when describing fuel starvation mayday to ATC 

[Mufflerbearing]

I'm so glad that I didn't know any of this when I was training to get my PPL.  I practiced slipping my plane to pass my test and then I had to show my DPE that maneuver to pass my test.  I really would have been scared to do this maneuver if I knew I was going to die doing it.

I always felt in control and the plane felt very stable.  Of course, keeping the nose pointing at the numbers helps

[carusoam]

4 hours ago, Mufflerbearing said:

I'm so glad that I didn't know any of this when I was training to get my PPL.  I practiced slipping my plane to pass my test and then I had to show my DPE that maneuver to pass my test.  I really would have been scared to do this maneuver if I knew I was going to die doing it.

I always felt in control and the plane felt very stable.  Of course, keeping the nose pointing at the numbers helps

MB,

Please be aware of the the things that affect a Long Body during Cross controlled flight...

1) All the usual things that affect all airplanes, including the fuel unporting issue...

2) Flaps down + X-controlled = disturbed airflow over the tail...

3) Disturbed airflow over the tail = increased chances of tail stall...

Recovery from tail stalls at low altitude is unlikely...

4) Why this is long body specific? Something about the size of the shadow, and distance to the tail....

5) There is a reason that all LBs got speed brakes... including the Eagle...  if the speed brakes were solely a luxury item...  The Eagle would not have all gotten them...

6) Blanketing the tail doesn’t happen 100% of the time, under all conditions... it happened once, under the right conditions, and was documented as the cause of a fatal accident...

7) These are only PP thoughts, Best to seek a Mooney specific CFI for a more clear explation.

8) Proper use of speed brakes is a pretty amazing tool.  Pretty much eliminates the need to experiment with strong X-controlled inputs...

9) Flight training has evolved a bit... practicing recognition of things and avoidance of things more than recovery from things...  

10) Can you feel the blanketing of flight controls? Probably feels like ordinary turbulence.... until the horizontal stabilizer doesn’t stabilize...(?)

PP thoughts only, not trying to point fingers at MB who has more flight training in his LB than I ever will... 

Best regards,

-a-

[Mufflerbearing]

This was my argument with my instructor and the DPE during my test.  I had heard of this issue, but they were adamant about the importance of showing that I could do this maneuver.  It was a requirement.  I mentioned that, why would I ever slip my plane when I had speed brakes? 

If this is a PPL test requirement how does one take this test and convince the DPE  that this is an unsafe maneuver in this plane and it is better wisdom that we don't do it?